[PULL 00/28] Block layer patches

[PULL 00/28] Block layer patches

[Kevin Wolf]

The following changes since commit 005ad32358f12fe9313a4a01918a55e60d4f39e5:

  Merge tag 'pull-tpm-2023-09-12-3' of https://github.com/stefanberger/qemu-tpm into staging (2023-09-13 13:41:57 -0400)

are available in the Git repository at:

  https://repo.or.cz/qemu/kevin.git tags/for-upstream

for you to fetch changes up to 5d96864b73225ee61b0dad7e928f0cddf14270fc:

  block-coroutine-wrapper: use qemu_get_current_aio_context() (2023-09-15 15:49:14 +0200)

----------------------------------------------------------------
Block layer patches

- Graph locking part 4 (node management)
- qemu-img map: report compressed data blocks
- block-backend: process I/O in the current AioContext

----------------------------------------------------------------
Andrey Drobyshev via (2):
      block: add BDRV_BLOCK_COMPRESSED flag for bdrv_block_status()
      qemu-img: map: report compressed data blocks

Kevin Wolf (21):
      block: Remove unused BlockReopenQueueEntry.perms_checked
      preallocate: Factor out preallocate_truncate_to_real_size()
      preallocate: Don't poll during permission updates
      block: Take AioContext lock for bdrv_append() more consistently
      block: Introduce bdrv_schedule_unref()
      block-coroutine-wrapper: Add no_co_wrapper_bdrv_wrlock functions
      block-coroutine-wrapper: Allow arbitrary parameter names
      block: Mark bdrv_replace_child_noperm() GRAPH_WRLOCK
      block: Mark bdrv_replace_child_tran() GRAPH_WRLOCK
      block: Mark bdrv_attach_child_common() GRAPH_WRLOCK
      block: Call transaction callbacks with lock held
      block: Mark bdrv_attach_child() GRAPH_WRLOCK
      block: Mark bdrv_parent_perms_conflict() and callers GRAPH_RDLOCK
      block: Mark bdrv_get_cumulative_perm() and callers GRAPH_RDLOCK
      block: Mark bdrv_child_perm() GRAPH_RDLOCK
      block: Mark bdrv_parent_cb_change_media() GRAPH_RDLOCK
      block: Take graph rdlock in bdrv_drop_intermediate()
      block: Take graph rdlock in bdrv_change_aio_context()
      block: Mark bdrv_root_unref_child() GRAPH_WRLOCK
      block: Mark bdrv_unref_child() GRAPH_WRLOCK
      block: Mark bdrv_add/del_child() and caller GRAPH_WRLOCK

Stefan Hajnoczi (5):
      block: remove AIOCBInfo->get_aio_context()
      test-bdrv-drain: avoid race with BH in IOThread drain test
      block-backend: process I/O in the current AioContext
      block-backend: process zoned requests in the current AioContext
      block-coroutine-wrapper: use qemu_get_current_aio_context()

 qapi/block-core.json                             |   6 +-
 include/block/aio.h                              |   1 -
 include/block/block-common.h                     |   7 +
 include/block/block-global-state.h               |  32 +-
 include/block/block-io.h                         |   1 -
 include/block/block_int-common.h                 |  34 +-
 include/block/block_int-global-state.h           |  14 +-
 include/sysemu/block-backend-global-state.h      |   4 +-
 block.c                                          | 348 +++++++---
 block/blklogwrites.c                             |   4 +
 block/blkverify.c                                |   2 +
 block/block-backend.c                            |  64 +-
 block/copy-before-write.c                        |  10 +-
 block/crypto.c                                   |   6 +-
 block/graph-lock.c                               |  26 +-
 block/io.c                                       |  23 +-
 block/mirror.c                                   |   8 +
 block/preallocate.c                              | 133 ++--
 block/qcow.c                                     |   5 +-
 block/qcow2.c                                    |   7 +-
 block/quorum.c                                   |  23 +-
 block/replication.c                              |   9 +
 block/snapshot.c                                 |   2 +
 block/stream.c                                   |  20 +-
 block/vmdk.c                                     |  15 +
 blockdev.c                                       |  23 +-
 blockjob.c                                       |   2 +
 hw/nvme/ctrl.c                                   |   7 -
 qemu-img.c                                       |   8 +-
 softmmu/dma-helpers.c                            |   8 -
 tests/unit/test-bdrv-drain.c                     |  31 +-
 tests/unit/test-bdrv-graph-mod.c                 |  20 +
 tests/unit/test-block-iothread.c                 |   3 +
 util/thread-pool.c                               |   8 -
 scripts/block-coroutine-wrapper.py               |  24 +-
 tests/qemu-iotests/051.pc.out                    |   6 +-
 tests/qemu-iotests/122.out                       |  84 +--
 tests/qemu-iotests/146.out                       | 780 +++++++++++------------
 tests/qemu-iotests/154.out                       | 194 +++---
 tests/qemu-iotests/179.out                       | 178 +++---
 tests/qemu-iotests/209.out                       |   4 +-
 tests/qemu-iotests/221.out                       |  16 +-
 tests/qemu-iotests/223.out                       |  60 +-
 tests/qemu-iotests/241.out                       |  10 +-
 tests/qemu-iotests/244.out                       |  24 +-
 tests/qemu-iotests/252.out                       |  10 +-
 tests/qemu-iotests/253.out                       |  20 +-
 tests/qemu-iotests/274.out                       |  48 +-
 tests/qemu-iotests/tests/nbd-qemu-allocation.out |  16 +-
 tests/qemu-iotests/tests/qemu-img-bitmaps.out    |  24 +-
 50 files changed, 1376 insertions(+), 1036 deletions(-)

[PULL 01/28] block: Remove unused BlockReopenQueueEntry.perms_checked

[Kevin Wolf]

This field has been unused since commit 72373e40fbc ('block:
bdrv_reopen_multiple: refresh permissions on updated graph').
Remove it.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-2-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/block.c b/block.c
index 8da89aaa62..9029ddd9ff 100644
--- a/block.c
+++ b/block.c
@@ -2115,7 +2115,6 @@ static int bdrv_fill_options(QDict **options, const char *filename,
 
 typedef struct BlockReopenQueueEntry {
      bool prepared;
-     bool perms_checked;
      BDRVReopenState state;
      QTAILQ_ENTRY(BlockReopenQueueEntry) entry;
 } BlockReopenQueueEntry;
-- 
2.41.0

[PULL 02/28] preallocate: Factor out preallocate_truncate_to_real_size()

[Kevin Wolf]

It's essentially the same code in preallocate_check_perm() and
preallocate_close(), except that the latter ignores errors.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-3-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/preallocate.c | 48 +++++++++++++++++++++------------------------
 1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/block/preallocate.c b/block/preallocate.c
index 3d0f621003..3173d80534 100644
--- a/block/preallocate.c
+++ b/block/preallocate.c
@@ -162,26 +162,39 @@ static int preallocate_open(BlockDriverState *bs, QDict *options, int flags,
     return 0;
 }
 
-static void preallocate_close(BlockDriverState *bs)
+static int preallocate_truncate_to_real_size(BlockDriverState *bs, Error **errp)
 {
-    int ret;
     BDRVPreallocateState *s = bs->opaque;
-
-    if (s->data_end < 0) {
-        return;
-    }
+    int ret;
 
     if (s->file_end < 0) {
         s->file_end = bdrv_getlength(bs->file->bs);
         if (s->file_end < 0) {
-            return;
+            error_setg_errno(errp, -s->file_end, "Failed to get file length");
+            return s->file_end;
         }
     }
 
     if (s->data_end < s->file_end) {
         ret = bdrv_truncate(bs->file, s->data_end, true, PREALLOC_MODE_OFF, 0,
                             NULL);
-        s->file_end = ret < 0 ? ret : s->data_end;
+        if (ret < 0) {
+            error_setg_errno(errp, -ret, "Failed to drop preallocation");
+            s->file_end = ret;
+            return ret;
+        }
+        s->file_end = s->data_end;
+    }
+
+    return 0;
+}
+
+static void preallocate_close(BlockDriverState *bs)
+{
+    BDRVPreallocateState *s = bs->opaque;
+
+    if (s->data_end >= 0) {
+        preallocate_truncate_to_real_size(bs, NULL);
     }
 }
 
@@ -473,24 +486,7 @@ static int preallocate_check_perm(BlockDriverState *bs,
          * We should truncate in check_perm, as in set_perm bs->file->perm will
          * be already changed, and we should not violate it.
          */
-        if (s->file_end < 0) {
-            s->file_end = bdrv_getlength(bs->file->bs);
-            if (s->file_end < 0) {
-                error_setg(errp, "Failed to get file length");
-                return s->file_end;
-            }
-        }
-
-        if (s->data_end < s->file_end) {
-            int ret = bdrv_truncate(bs->file, s->data_end, true,
-                                    PREALLOC_MODE_OFF, 0, NULL);
-            if (ret < 0) {
-                error_setg(errp, "Failed to drop preallocation");
-                s->file_end = ret;
-                return ret;
-            }
-            s->file_end = s->data_end;
-        }
+        return preallocate_truncate_to_real_size(bs, errp);
     }
 
     return 0;
-- 
2.41.0

[PULL 03/28] preallocate: Don't poll during permission updates

[Kevin Wolf]

When the permission related BlockDriver callbacks are called, we are in
the middle of an operation traversing the block graph. Polling in such a
place is a very bad idea because the graph could change in unexpected
ways. In the future, callers will also hold the graph lock, which is
likely to turn polling into a deadlock.

So we need to get rid of calls to functions like bdrv_getlength() or
bdrv_truncate() there as these functions poll internally. They are
currently used so that when no parent has write/resize permissions on
the image any more, the preallocate filter drops the extra preallocated
area in the image file and gives up write/resize permissions itself.

In order to achieve this without polling in .bdrv_check_perm, don't
immediately truncate the image, but only schedule a BH to do so. The
filter keeps the write/resize permissions a bit longer now until the BH
has executed.

There is one case in which delaying doesn't work: Reopening the image
read-only. In this case, bs->file will likely be reopened read-only,
too, so keeping write permissions a bit longer on it doesn't work. But
we can already cover this case in preallocate_reopen_prepare() and not
rely on the permission updates for it.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-4-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/preallocate.c | 89 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 69 insertions(+), 20 deletions(-)

diff --git a/block/preallocate.c b/block/preallocate.c
index 3173d80534..bfb638d8b1 100644
--- a/block/preallocate.c
+++ b/block/preallocate.c
@@ -75,8 +75,14 @@ typedef struct BDRVPreallocateState {
      * be invalid (< 0) when we don't have both exclusive BLK_PERM_RESIZE and
      * BLK_PERM_WRITE permissions on file child.
      */
+
+    /* Gives up the resize permission on children when parents don't need it */
+    QEMUBH *drop_resize_bh;
 } BDRVPreallocateState;
 
+static int preallocate_drop_resize(BlockDriverState *bs, Error **errp);
+static void preallocate_drop_resize_bh(void *opaque);
+
 #define PREALLOCATE_OPT_PREALLOC_ALIGN "prealloc-align"
 #define PREALLOCATE_OPT_PREALLOC_SIZE "prealloc-size"
 static QemuOptsList runtime_opts = {
@@ -142,6 +148,7 @@ static int preallocate_open(BlockDriverState *bs, QDict *options, int flags,
      * For this to work, mark them invalid.
      */
     s->file_end = s->zero_start = s->data_end = -EINVAL;
+    s->drop_resize_bh = qemu_bh_new(preallocate_drop_resize_bh, bs);
 
     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
     if (ret < 0) {
@@ -193,6 +200,9 @@ static void preallocate_close(BlockDriverState *bs)
 {
     BDRVPreallocateState *s = bs->opaque;
 
+    qemu_bh_cancel(s->drop_resize_bh);
+    qemu_bh_delete(s->drop_resize_bh);
+
     if (s->data_end >= 0) {
         preallocate_truncate_to_real_size(bs, NULL);
     }
@@ -211,6 +221,7 @@ static int preallocate_reopen_prepare(BDRVReopenState *reopen_state,
                                       BlockReopenQueue *queue, Error **errp)
 {
     PreallocateOpts *opts = g_new0(PreallocateOpts, 1);
+    int ret;
 
     if (!preallocate_absorb_opts(opts, reopen_state->options,
                                  reopen_state->bs->file->bs, errp)) {
@@ -218,6 +229,19 @@ static int preallocate_reopen_prepare(BDRVReopenState *reopen_state,
         return -EINVAL;
     }
 
+    /*
+     * Drop the preallocation already here if reopening read-only. The child
+     * might also be reopened read-only and then scheduling a BH during the
+     * permission update is too late.
+     */
+    if ((reopen_state->flags & BDRV_O_RDWR) == 0) {
+        ret = preallocate_drop_resize(reopen_state->bs, errp);
+        if (ret < 0) {
+            g_free(opts);
+            return ret;
+        }
+    }
+
     reopen_state->opaque = opts;
 
     return 0;
@@ -475,41 +499,61 @@ preallocate_co_getlength(BlockDriverState *bs)
     return ret;
 }
 
-static int preallocate_check_perm(BlockDriverState *bs,
-                                  uint64_t perm, uint64_t shared, Error **errp)
+static int preallocate_drop_resize(BlockDriverState *bs, Error **errp)
 {
     BDRVPreallocateState *s = bs->opaque;
+    int ret;
 
-    if (s->data_end >= 0 && !can_write_resize(perm)) {
-        /*
-         * Lose permissions.
-         * We should truncate in check_perm, as in set_perm bs->file->perm will
-         * be already changed, and we should not violate it.
-         */
-        return preallocate_truncate_to_real_size(bs, errp);
+    if (s->data_end < 0) {
+        return 0;
+    }
+
+    /*
+     * Before switching children to be read-only, truncate them to remove
+     * the preallocation and let them have the real size.
+     */
+    ret = preallocate_truncate_to_real_size(bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
+    /*
+     * We'll drop our permissions and will allow other users to take write and
+     * resize permissions (see preallocate_child_perm). Anyone will be able to
+     * change the child, so mark all states invalid. We'll regain control if a
+     * parent requests write access again.
+     */
+    s->data_end = s->file_end = s->zero_start = -EINVAL;
+
+    bdrv_graph_rdlock_main_loop();
+    bdrv_child_refresh_perms(bs, bs->file, NULL);
+    bdrv_graph_rdunlock_main_loop();
+
     return 0;
 }
 
+static void preallocate_drop_resize_bh(void *opaque)
+{
+    /*
+     * In case of errors, we'll simply keep the exclusive lock on the image
+     * indefinitely.
+     */
+    preallocate_drop_resize(opaque, NULL);
+}
+
 static void preallocate_set_perm(BlockDriverState *bs,
                                  uint64_t perm, uint64_t shared)
 {
     BDRVPreallocateState *s = bs->opaque;
 
     if (can_write_resize(perm)) {
+        qemu_bh_cancel(s->drop_resize_bh);
         if (s->data_end < 0) {
             s->data_end = s->file_end = s->zero_start =
-                bdrv_getlength(bs->file->bs);
+                bs->file->bs->total_sectors * BDRV_SECTOR_SIZE;
         }
     } else {
-        /*
-         * We drop our permissions, as well as allow shared
-         * permissions (see preallocate_child_perm), anyone will be able to
-         * change the child, so mark all states invalid. We'll regain control if
-         * get good permissions back.
-         */
-        s->data_end = s->file_end = s->zero_start = -EINVAL;
+        qemu_bh_schedule(s->drop_resize_bh);
     }
 }
 
@@ -517,10 +561,16 @@ static void preallocate_child_perm(BlockDriverState *bs, BdrvChild *c,
     BdrvChildRole role, BlockReopenQueue *reopen_queue,
     uint64_t perm, uint64_t shared, uint64_t *nperm, uint64_t *nshared)
 {
+    BDRVPreallocateState *s = bs->opaque;
+
     bdrv_default_perms(bs, c, role, reopen_queue, perm, shared, nperm, nshared);
 
-    if (can_write_resize(perm)) {
-        /* This should come by default, but let's enforce: */
+    /*
+     * We need exclusive write and resize permissions on the child not only when
+     * the parent can write to it, but also after the parent gave up write
+     * permissions until preallocate_drop_resize() has completed.
+     */
+    if (can_write_resize(perm) || s->data_end != -EINVAL) {
         *nperm |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
 
         /*
@@ -550,7 +600,6 @@ static BlockDriver bdrv_preallocate_filter = {
     .bdrv_co_flush = preallocate_co_flush,
     .bdrv_co_truncate = preallocate_co_truncate,
 
-    .bdrv_check_perm = preallocate_check_perm,
     .bdrv_set_perm = preallocate_set_perm,
     .bdrv_child_perm = preallocate_child_perm,
 
-- 
2.41.0

[PULL 04/28] block: Take AioContext lock for bdrv_append() more consistently

[Kevin Wolf]

The documentation for bdrv_append() says that the caller must hold the
AioContext lock for bs_top. Change all callers to actually adhere to the
contract.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-5-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 tests/unit/test-bdrv-drain.c     | 3 +++
 tests/unit/test-bdrv-graph-mod.c | 6 ++++++
 tests/unit/test-block-iothread.c | 3 +++
 3 files changed, 12 insertions(+)

diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index ccc453c29e..89c8fa6780 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -1359,7 +1359,10 @@ static void test_append_to_drained(void)
     g_assert_cmpint(base_s->drain_count, ==, 1);
     g_assert_cmpint(base->in_flight, ==, 0);
 
+    aio_context_acquire(qemu_get_aio_context());
     bdrv_append(overlay, base, &error_abort);
+    aio_context_release(qemu_get_aio_context());
+
     g_assert_cmpint(base->in_flight, ==, 0);
     g_assert_cmpint(overlay->in_flight, ==, 0);
 
diff --git a/tests/unit/test-bdrv-graph-mod.c b/tests/unit/test-bdrv-graph-mod.c
index 36eed4b464..d8503165b3 100644
--- a/tests/unit/test-bdrv-graph-mod.c
+++ b/tests/unit/test-bdrv-graph-mod.c
@@ -140,8 +140,10 @@ static void test_update_perm_tree(void)
     bdrv_attach_child(filter, bs, "child", &child_of_bds,
                       BDRV_CHILD_DATA, &error_abort);
 
+    aio_context_acquire(qemu_get_aio_context());
     ret = bdrv_append(filter, bs, NULL);
     g_assert_cmpint(ret, <, 0);
+    aio_context_release(qemu_get_aio_context());
 
     bdrv_unref(filter);
     blk_unref(root);
@@ -205,7 +207,9 @@ static void test_should_update_child(void)
     g_assert(target->backing->bs == bs);
     bdrv_attach_child(filter, target, "target", &child_of_bds,
                       BDRV_CHILD_DATA, &error_abort);
+    aio_context_acquire(qemu_get_aio_context());
     bdrv_append(filter, bs, &error_abort);
+    aio_context_release(qemu_get_aio_context());
     g_assert(target->backing->bs == bs);
 
     bdrv_unref(filter);
@@ -410,7 +414,9 @@ static void test_append_greedy_filter(void)
                       BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
                       &error_abort);
 
+    aio_context_acquire(qemu_get_aio_context());
     bdrv_append(fl, base, &error_abort);
+    aio_context_release(qemu_get_aio_context());
     bdrv_unref(fl);
     bdrv_unref(top);
 }
diff --git a/tests/unit/test-block-iothread.c b/tests/unit/test-block-iothread.c
index d727a5fee8..9155547313 100644
--- a/tests/unit/test-block-iothread.c
+++ b/tests/unit/test-block-iothread.c
@@ -756,11 +756,14 @@ static void test_propagate_mirror(void)
                                   &error_abort);
 
     /* Start a mirror job */
+    aio_context_acquire(main_ctx);
     mirror_start("job0", src, target, NULL, JOB_DEFAULT, 0, 0, 0,
                  MIRROR_SYNC_MODE_NONE, MIRROR_OPEN_BACKING_CHAIN, false,
                  BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT,
                  false, "filter_node", MIRROR_COPY_MODE_BACKGROUND,
                  &error_abort);
+    aio_context_release(main_ctx);
+
     WITH_JOB_LOCK_GUARD() {
         job = job_get_locked("job0");
     }
-- 
2.41.0

[PULL 05/28] block: Introduce bdrv_schedule_unref()

[Kevin Wolf]

bdrv_unref() is called by a lot of places that need to hold the graph
lock (it naturally happens in the context of operations that change the
graph). However, bdrv_unref() takes the graph writer lock internally, so
it can't actually be called while already holding a graph lock without
causing a deadlock.

bdrv_unref() also can't just become GRAPH_WRLOCK because it drains the
node before closing it, and draining requires that the graph is
unlocked.

The solution is to defer deleting the node until we don't hold the lock
any more and draining is possible again.

Note that keeping images open for longer than necessary can create
problems, too: You can't open an image again before it is really closed
(if image locking didn't prevent it, it would cause corruption).
Reopening an image immediately happens at least during bdrv_open() and
bdrv_co_create().

In order to solve this problem, make sure to run the deferred unref in
bdrv_graph_wrunlock(), i.e. the first possible place where we can drain
again. This is also why bdrv_schedule_unref() is marked GRAPH_WRLOCK.

The output of iotest 051 is updated because the additional polling
changes the order of HMP output, resulting in a new "(qemu)" prompt in
the test output that was previously on a separate line and filtered out.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230911094620.45040-6-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-global-state.h |  1 +
 block.c                            | 17 +++++++++++++++++
 block/graph-lock.c                 | 26 +++++++++++++++++++-------
 tests/qemu-iotests/051.pc.out      |  6 +++---
 4 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index f347199bff..e570799f85 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -224,6 +224,7 @@ void bdrv_img_create(const char *filename, const char *fmt,
 void bdrv_ref(BlockDriverState *bs);
 void no_coroutine_fn bdrv_unref(BlockDriverState *bs);
 void coroutine_fn no_co_wrapper bdrv_co_unref(BlockDriverState *bs);
+void GRAPH_WRLOCK bdrv_schedule_unref(BlockDriverState *bs);
 void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child);
 BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
                              BlockDriverState *child_bs,
diff --git a/block.c b/block.c
index 9029ddd9ff..c8ac7cfac4 100644
--- a/block.c
+++ b/block.c
@@ -7044,6 +7044,23 @@ void bdrv_unref(BlockDriverState *bs)
     }
 }
 
+/*
+ * Release a BlockDriverState reference while holding the graph write lock.
+ *
+ * Calling bdrv_unref() directly is forbidden while holding the graph lock
+ * because bdrv_close() both involves polling and taking the graph lock
+ * internally. bdrv_schedule_unref() instead delays decreasing the refcount and
+ * possibly closing @bs until the graph lock is released.
+ */
+void bdrv_schedule_unref(BlockDriverState *bs)
+{
+    if (!bs) {
+        return;
+    }
+    aio_bh_schedule_oneshot(qemu_get_aio_context(),
+                            (QEMUBHFunc *) bdrv_unref, bs);
+}
+
 struct BdrvOpBlocker {
     Error *reason;
     QLIST_ENTRY(BdrvOpBlocker) list;
diff --git a/block/graph-lock.c b/block/graph-lock.c
index f357a2c0b1..58a799065f 100644
--- a/block/graph-lock.c
+++ b/block/graph-lock.c
@@ -163,17 +163,29 @@ void bdrv_graph_wrlock(BlockDriverState *bs)
 void bdrv_graph_wrunlock(void)
 {
     GLOBAL_STATE_CODE();
-    QEMU_LOCK_GUARD(&aio_context_list_lock);
     assert(qatomic_read(&has_writer));
 
+    WITH_QEMU_LOCK_GUARD(&aio_context_list_lock) {
+        /*
+         * No need for memory barriers, this works in pair with
+         * the slow path of rdlock() and both take the lock.
+         */
+        qatomic_store_release(&has_writer, 0);
+
+        /* Wake up all coroutines that are waiting to read the graph */
+        qemu_co_enter_all(&reader_queue, &aio_context_list_lock);
+    }
+
     /*
-     * No need for memory barriers, this works in pair with
-     * the slow path of rdlock() and both take the lock.
+     * Run any BHs that were scheduled during the wrlock section and that
+     * callers might expect to have finished (in particular, this is important
+     * for bdrv_schedule_unref()).
+     *
+     * Do this only after restarting coroutines so that nested event loops in
+     * BHs don't deadlock if their condition relies on the coroutine making
+     * progress.
      */
-    qatomic_store_release(&has_writer, 0);
-
-    /* Wake up all coroutine that are waiting to read the graph */
-    qemu_co_enter_all(&reader_queue, &aio_context_list_lock);
+    aio_bh_poll(qemu_get_aio_context());
 }
 
 void coroutine_fn bdrv_graph_co_rdlock(void)
diff --git a/tests/qemu-iotests/051.pc.out b/tests/qemu-iotests/051.pc.out
index 4d4af5a486..7e10c5fa1b 100644
--- a/tests/qemu-iotests/051.pc.out
+++ b/tests/qemu-iotests/051.pc.out
@@ -169,11 +169,11 @@ QEMU_PROG: -device scsi-hd,drive=disk: Device needs media, but drive is empty
 
 Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device ide-hd,drive=disk,share-rw=on
 QEMU X.Y.Z monitor - type 'help' for more information
-QEMU_PROG: -device ide-hd,drive=disk,share-rw=on: Cannot change iothread of active block backend
+(qemu) QEMU_PROG: -device ide-hd,drive=disk,share-rw=on: Cannot change iothread of active block backend
 
 Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device virtio-blk-pci,drive=disk,share-rw=on
 QEMU X.Y.Z monitor - type 'help' for more information
-QEMU_PROG: -device virtio-blk-pci,drive=disk,share-rw=on: Cannot change iothread of active block backend
+(qemu) QEMU_PROG: -device virtio-blk-pci,drive=disk,share-rw=on: Cannot change iothread of active block backend
 
 Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device lsi53c895a,id=lsi0 -device scsi-hd,bus=lsi0.0,drive=disk,share-rw=on
 QEMU X.Y.Z monitor - type 'help' for more information
@@ -185,7 +185,7 @@ QEMU X.Y.Z monitor - type 'help' for more information
 
 Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device virtio-blk-pci,drive=disk,iothread=thread0,share-rw=on
 QEMU X.Y.Z monitor - type 'help' for more information
-QEMU_PROG: -device virtio-blk-pci,drive=disk,iothread=thread0,share-rw=on: Cannot change iothread of active block backend
+(qemu) QEMU_PROG: -device virtio-blk-pci,drive=disk,iothread=thread0,share-rw=on: Cannot change iothread of active block backend
 
 Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device virtio-scsi,id=virtio-scsi1,iothread=thread0 -device scsi-hd,bus=virtio-scsi1.0,drive=disk,share-rw=on
 QEMU X.Y.Z monitor - type 'help' for more information
-- 
2.41.0

[PULL 06/28] block-coroutine-wrapper: Add no_co_wrapper_bdrv_wrlock functions

[Kevin Wolf]

Add a new wrapper type for GRAPH_WRLOCK functions that should be called
from coroutine context.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-7-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-common.h       |  4 ++++
 scripts/block-coroutine-wrapper.py | 11 +++++++++++
 2 files changed, 15 insertions(+)

diff --git a/include/block/block-common.h b/include/block/block-common.h
index df5ffc8d09..3bbc5d9294 100644
--- a/include/block/block-common.h
+++ b/include/block/block-common.h
@@ -66,10 +66,14 @@
  * function. The coroutine yields after scheduling the BH and is reentered when
  * the wrapped function returns.
  *
+ * A no_co_wrapper_bdrv_wrlock function is a no_co_wrapper function that
+ * automatically takes the graph wrlock when calling the wrapped function.
+ *
  * If the first parameter of the function is a BlockDriverState, BdrvChild or
  * BlockBackend pointer, the AioContext lock for it is taken in the wrapper.
  */
 #define no_co_wrapper
+#define no_co_wrapper_bdrv_wrlock
 
 #include "block/blockjob.h"
 
diff --git a/scripts/block-coroutine-wrapper.py b/scripts/block-coroutine-wrapper.py
index d4a183db61..fa01c06567 100644
--- a/scripts/block-coroutine-wrapper.py
+++ b/scripts/block-coroutine-wrapper.py
@@ -71,10 +71,13 @@ def __init__(self, wrapper_type: str, return_type: str, name: str,
         self.args = [ParamDecl(arg.strip()) for arg in args.split(',')]
         self.create_only_co = 'mixed' not in variant
         self.graph_rdlock = 'bdrv_rdlock' in variant
+        self.graph_wrlock = 'bdrv_wrlock' in variant
 
         self.wrapper_type = wrapper_type
 
         if wrapper_type == 'co':
+            if self.graph_wrlock:
+                raise ValueError(f"co function can't be wrlock: {self.name}")
             subsystem, subname = self.name.split('_', 1)
             self.target_name = f'{subsystem}_co_{subname}'
         else:
@@ -250,6 +253,12 @@ def gen_no_co_wrapper(func: FuncDecl) -> str:
     name = func.target_name
     struct_name = func.struct_name
 
+    graph_lock=''
+    graph_unlock=''
+    if func.graph_wrlock:
+        graph_lock='    bdrv_graph_wrlock(NULL);'
+        graph_unlock='    bdrv_graph_wrunlock();'
+
     return f"""\
 /*
  * Wrappers for {name}
@@ -266,9 +275,11 @@ def gen_no_co_wrapper(func: FuncDecl) -> str:
     {struct_name} *s = opaque;
     AioContext *ctx = {func.gen_ctx('s->')};
 
+{graph_lock}
     aio_context_acquire(ctx);
     {func.get_result}{name}({ func.gen_list('s->{name}') });
     aio_context_release(ctx);
+{graph_unlock}
 
     aio_co_wake(s->co);
 }}
-- 
2.41.0

[PULL 07/28] block-coroutine-wrapper: Allow arbitrary parameter names

[Kevin Wolf]

Don't assume specific parameter names like 'bs' or 'blk' in the
generated code, but use the actual name.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-8-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 scripts/block-coroutine-wrapper.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/scripts/block-coroutine-wrapper.py b/scripts/block-coroutine-wrapper.py
index fa01c06567..685d0b4ed4 100644
--- a/scripts/block-coroutine-wrapper.py
+++ b/scripts/block-coroutine-wrapper.py
@@ -105,12 +105,13 @@ def __init__(self, wrapper_type: str, return_type: str, name: str,
 
     def gen_ctx(self, prefix: str = '') -> str:
         t = self.args[0].type
+        name = self.args[0].name
         if t == 'BlockDriverState *':
-            return f'bdrv_get_aio_context({prefix}bs)'
+            return f'bdrv_get_aio_context({prefix}{name})'
         elif t == 'BdrvChild *':
-            return f'bdrv_get_aio_context({prefix}child->bs)'
+            return f'bdrv_get_aio_context({prefix}{name}->bs)'
         elif t == 'BlockBackend *':
-            return f'blk_get_aio_context({prefix}blk)'
+            return f'blk_get_aio_context({prefix}{name})'
         else:
             return 'qemu_get_aio_context()'
 
-- 
2.41.0

[PULL 08/28] block: Mark bdrv_replace_child_noperm() GRAPH_WRLOCK

[Kevin Wolf]

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_replace_child_noperm(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-9-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/block.c b/block.c
index c8ac7cfac4..61856f5c33 100644
--- a/block.c
+++ b/block.c
@@ -91,8 +91,9 @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
 static bool bdrv_recurse_has_child(BlockDriverState *bs,
                                    BlockDriverState *child);
 
-static void bdrv_replace_child_noperm(BdrvChild *child,
-                                      BlockDriverState *new_bs);
+static void GRAPH_WRLOCK
+bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs);
+
 static void bdrv_remove_child(BdrvChild *child, Transaction *tran);
 
 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
@@ -2387,6 +2388,8 @@ static void bdrv_replace_child_abort(void *opaque)
     BlockDriverState *new_bs = s->child->bs;
 
     GLOBAL_STATE_CODE();
+    bdrv_graph_wrlock(s->old_bs);
+
     /* old_bs reference is transparently moved from @s to @s->child */
     if (!s->child->bs) {
         /*
@@ -2403,6 +2406,8 @@ static void bdrv_replace_child_abort(void *opaque)
     }
     assert(s->child->quiesced_parent);
     bdrv_replace_child_noperm(s->child, s->old_bs);
+
+    bdrv_graph_wrunlock();
     bdrv_unref(new_bs);
 }
 
@@ -2439,7 +2444,10 @@ static void bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
     if (new_bs) {
         bdrv_ref(new_bs);
     }
+
+    bdrv_graph_wrlock(new_bs);
     bdrv_replace_child_noperm(child, new_bs);
+    bdrv_graph_wrunlock();
     /* old_bs reference is transparently moved from @child to @s */
 }
 
@@ -2858,8 +2866,8 @@ uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm)
  * If @new_bs is non-NULL, the parent of @child must already be drained through
  * @child and the caller must hold the AioContext lock for @new_bs.
  */
-static void bdrv_replace_child_noperm(BdrvChild *child,
-                                      BlockDriverState *new_bs)
+static void GRAPH_WRLOCK
+bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs)
 {
     BlockDriverState *old_bs = child->bs;
     int new_bs_quiesce_counter;
@@ -2894,8 +2902,6 @@ static void bdrv_replace_child_noperm(BdrvChild *child,
         assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
     }
 
-    /* TODO Pull this up into the callers to avoid polling here */
-    bdrv_graph_wrlock(new_bs);
     if (old_bs) {
         if (child->klass->detach) {
             child->klass->detach(child);
@@ -2911,7 +2917,6 @@ static void bdrv_replace_child_noperm(BdrvChild *child,
             child->klass->attach(child);
         }
     }
-    bdrv_graph_wrunlock();
 
     /*
      * If the parent was drained through this BdrvChild previously, but new_bs
@@ -2952,7 +2957,10 @@ static void bdrv_attach_child_common_abort(void *opaque)
     BlockDriverState *bs = s->child->bs;
 
     GLOBAL_STATE_CODE();
+
+    bdrv_graph_wrlock(NULL);
     bdrv_replace_child_noperm(s->child, NULL);
+    bdrv_graph_wrunlock();
 
     if (bdrv_get_aio_context(bs) != s->old_child_ctx) {
         bdrv_try_change_aio_context(bs, s->old_child_ctx, NULL, &error_abort);
@@ -3080,8 +3088,10 @@ static BdrvChild *bdrv_attach_child_common(BlockDriverState *child_bs,
      * a problem, we already did this), but it will still poll until the parent
      * is fully quiesced, so it will not be negatively affected either.
      */
+    bdrv_graph_wrlock(child_bs);
     bdrv_parent_drained_begin_single(new_child);
     bdrv_replace_child_noperm(new_child, child_bs);
+    bdrv_graph_wrunlock();
 
     BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1);
     *s = (BdrvAttachChildCommonState) {
@@ -3225,7 +3235,9 @@ void bdrv_root_unref_child(BdrvChild *child)
     BlockDriverState *child_bs = child->bs;
 
     GLOBAL_STATE_CODE();
+    bdrv_graph_wrlock(NULL);
     bdrv_replace_child_noperm(child, NULL);
+    bdrv_graph_wrunlock();
     bdrv_child_free(child);
 
     if (child_bs) {
-- 
2.41.0

[PULL 09/28] block: Mark bdrv_replace_child_tran() GRAPH_WRLOCK

[Kevin Wolf]

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_replace_child_tran(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

While a graph lock is held, polling is not allowed. Therefore draining
the necessary nodes can no longer be done in bdrv_remove_child() and
bdrv_replace_node_noperm(), but the callers must already make sure that
they are drained.

Note that the transaction callbacks still take the lock internally, so
tran_finalize() must be called without the lock held. This is because
bdrv_append() also calls bdrv_attach_child_noperm(), which currently
requires to be called unlocked. Once it changes, the transaction
callbacks can be changed, too.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-10-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 78 ++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 50 insertions(+), 28 deletions(-)

diff --git a/block.c b/block.c
index 61856f5c33..0973b91d98 100644
--- a/block.c
+++ b/block.c
@@ -94,7 +94,8 @@ static bool bdrv_recurse_has_child(BlockDriverState *bs,
 static void GRAPH_WRLOCK
 bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs);
 
-static void bdrv_remove_child(BdrvChild *child, Transaction *tran);
+static void GRAPH_WRLOCK
+bdrv_remove_child(BdrvChild *child, Transaction *tran);
 
 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
                                BlockReopenQueue *queue,
@@ -2427,8 +2428,9 @@ static TransactionActionDrv bdrv_replace_child_drv = {
  *
  * The function doesn't update permissions, caller is responsible for this.
  */
-static void bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
-                                    Transaction *tran)
+static void GRAPH_WRLOCK
+bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
+                        Transaction *tran)
 {
     BdrvReplaceChildState *s = g_new(BdrvReplaceChildState, 1);
 
@@ -2445,9 +2447,7 @@ static void bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
         bdrv_ref(new_bs);
     }
 
-    bdrv_graph_wrlock(new_bs);
     bdrv_replace_child_noperm(child, new_bs);
-    bdrv_graph_wrunlock();
     /* old_bs reference is transparently moved from @child to @s */
 }
 
@@ -3439,8 +3439,14 @@ static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
     }
 
     if (child) {
+        bdrv_drained_begin(child->bs);
+        bdrv_graph_wrlock(NULL);
+
         bdrv_unset_inherits_from(parent_bs, child, tran);
         bdrv_remove_child(child, tran);
+
+        bdrv_graph_wrunlock();
+        bdrv_drained_end(child->bs);
     }
 
     if (!child_bs) {
@@ -5133,7 +5139,7 @@ void bdrv_close_all(void)
     assert(QTAILQ_EMPTY(&all_bdrv_states));
 }
 
-static bool should_update_child(BdrvChild *c, BlockDriverState *to)
+static bool GRAPH_RDLOCK should_update_child(BdrvChild *c, BlockDriverState *to)
 {
     GQueue *queue;
     GHashTable *found;
@@ -5222,45 +5228,41 @@ static TransactionActionDrv bdrv_remove_child_drv = {
     .commit = bdrv_remove_child_commit,
 };
 
-/* Function doesn't update permissions, caller is responsible for this. */
-static void bdrv_remove_child(BdrvChild *child, Transaction *tran)
+/*
+ * Function doesn't update permissions, caller is responsible for this.
+ *
+ * @child->bs (if non-NULL) must be drained.
+ */
+static void GRAPH_WRLOCK bdrv_remove_child(BdrvChild *child, Transaction *tran)
 {
     if (!child) {
         return;
     }
 
     if (child->bs) {
-        BlockDriverState *bs = child->bs;
-        bdrv_drained_begin(bs);
+        assert(child->quiesced_parent);
         bdrv_replace_child_tran(child, NULL, tran);
-        bdrv_drained_end(bs);
     }
 
     tran_add(tran, &bdrv_remove_child_drv, child);
 }
 
-static void undrain_on_clean_cb(void *opaque)
-{
-    bdrv_drained_end(opaque);
-}
-
-static TransactionActionDrv undrain_on_clean = {
-    .clean = undrain_on_clean_cb,
-};
-
-static int bdrv_replace_node_noperm(BlockDriverState *from,
-                                    BlockDriverState *to,
-                                    bool auto_skip, Transaction *tran,
-                                    Error **errp)
+/*
+ * Both @from and @to (if non-NULL) must be drained. @to must be kept drained
+ * until the transaction is completed.
+ */
+static int GRAPH_WRLOCK
+bdrv_replace_node_noperm(BlockDriverState *from,
+                         BlockDriverState *to,
+                         bool auto_skip, Transaction *tran,
+                         Error **errp)
 {
     BdrvChild *c, *next;
 
     GLOBAL_STATE_CODE();
 
-    bdrv_drained_begin(from);
-    bdrv_drained_begin(to);
-    tran_add(tran, &undrain_on_clean, from);
-    tran_add(tran, &undrain_on_clean, to);
+    assert(from->quiesce_counter);
+    assert(to->quiesce_counter);
 
     QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
         assert(c->bs == from);
@@ -5323,6 +5325,9 @@ static int bdrv_replace_node_common(BlockDriverState *from,
     assert(qemu_get_current_aio_context() == qemu_get_aio_context());
     assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to));
     bdrv_drained_begin(from);
+    bdrv_drained_begin(to);
+
+    bdrv_graph_wrlock(to);
 
     /*
      * Do the replacement without permission update.
@@ -5336,6 +5341,7 @@ static int bdrv_replace_node_common(BlockDriverState *from,
     }
 
     if (detach_subchain) {
+        /* to_cow_parent is already drained because from is drained */
         bdrv_remove_child(bdrv_filter_or_cow_child(to_cow_parent), tran);
     }
 
@@ -5350,8 +5356,10 @@ static int bdrv_replace_node_common(BlockDriverState *from,
     ret = 0;
 
 out:
+    bdrv_graph_wrunlock();
     tran_finalize(tran, ret);
 
+    bdrv_drained_end(to);
     bdrv_drained_end(from);
     bdrv_unref(from);
 
@@ -5395,6 +5403,7 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
     BdrvChild *child;
     Transaction *tran = tran_new();
     AioContext *old_context, *new_context = NULL;
+    bool drained = false;
 
     GLOBAL_STATE_CODE();
 
@@ -5423,7 +5432,13 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
         aio_context_acquire(new_context);
     }
 
+    bdrv_drained_begin(bs_new);
+    bdrv_drained_begin(bs_top);
+    drained = true;
+
+    bdrv_graph_wrlock(bs_new);
     ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp);
+    bdrv_graph_wrunlock();
     if (ret < 0) {
         goto out;
     }
@@ -5436,6 +5451,11 @@ out:
     bdrv_refresh_limits(bs_top, NULL, NULL);
     bdrv_graph_rdunlock_main_loop();
 
+    if (drained) {
+        bdrv_drained_end(bs_top);
+        bdrv_drained_end(bs_new);
+    }
+
     if (new_context && old_context != new_context) {
         aio_context_release(new_context);
         aio_context_acquire(old_context);
@@ -5458,6 +5478,7 @@ int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs,
     bdrv_ref(old_bs);
     bdrv_drained_begin(old_bs);
     bdrv_drained_begin(new_bs);
+    bdrv_graph_wrlock(new_bs);
 
     bdrv_replace_child_tran(child, new_bs, tran);
 
@@ -5465,6 +5486,7 @@ int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs,
     refresh_list = g_slist_prepend(refresh_list, new_bs);
 
     ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp);
+    bdrv_graph_wrunlock();
 
     tran_finalize(tran, ret);
 
-- 
2.41.0

[PULL 10/28] block: Mark bdrv_attach_child_common() GRAPH_WRLOCK

[Kevin Wolf]

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_attach_child_common(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Note that the transaction callbacks still take the lock internally, so
tran_finalize() must be called without the lock held. This is because
bdrv_append() also calls bdrv_replace_node_noperm(), which currently
requires the transaction callbacks to be called unlocked. In the next
step, both of them can be switched to locked tran_finalize() calls
together.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-11-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c        | 133 +++++++++++++++++++++++++++++++------------------
 block/stream.c |  20 ++++++--
 2 files changed, 100 insertions(+), 53 deletions(-)

diff --git a/block.c b/block.c
index 0973b91d98..f6e7cf4fb9 100644
--- a/block.c
+++ b/block.c
@@ -3004,13 +3004,14 @@ static TransactionActionDrv bdrv_attach_child_common_drv = {
  * @child_bs can move to a different AioContext in this function. Callers must
  * make sure that their AioContext locking is still correct after this.
  */
-static BdrvChild *bdrv_attach_child_common(BlockDriverState *child_bs,
-                                           const char *child_name,
-                                           const BdrvChildClass *child_class,
-                                           BdrvChildRole child_role,
-                                           uint64_t perm, uint64_t shared_perm,
-                                           void *opaque,
-                                           Transaction *tran, Error **errp)
+static BdrvChild * GRAPH_WRLOCK
+bdrv_attach_child_common(BlockDriverState *child_bs,
+                         const char *child_name,
+                         const BdrvChildClass *child_class,
+                         BdrvChildRole child_role,
+                         uint64_t perm, uint64_t shared_perm,
+                         void *opaque,
+                         Transaction *tran, Error **errp)
 {
     BdrvChild *new_child;
     AioContext *parent_ctx, *new_child_ctx;
@@ -3088,10 +3089,8 @@ static BdrvChild *bdrv_attach_child_common(BlockDriverState *child_bs,
      * a problem, we already did this), but it will still poll until the parent
      * is fully quiesced, so it will not be negatively affected either.
      */
-    bdrv_graph_wrlock(child_bs);
     bdrv_parent_drained_begin_single(new_child);
     bdrv_replace_child_noperm(new_child, child_bs);
-    bdrv_graph_wrunlock();
 
     BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1);
     *s = (BdrvAttachChildCommonState) {
@@ -3116,13 +3115,14 @@ static BdrvChild *bdrv_attach_child_common(BlockDriverState *child_bs,
  * @child_bs can move to a different AioContext in this function. Callers must
  * make sure that their AioContext locking is still correct after this.
  */
-static BdrvChild *bdrv_attach_child_noperm(BlockDriverState *parent_bs,
-                                           BlockDriverState *child_bs,
-                                           const char *child_name,
-                                           const BdrvChildClass *child_class,
-                                           BdrvChildRole child_role,
-                                           Transaction *tran,
-                                           Error **errp)
+static BdrvChild * GRAPH_WRLOCK
+bdrv_attach_child_noperm(BlockDriverState *parent_bs,
+                         BlockDriverState *child_bs,
+                         const char *child_name,
+                         const BdrvChildClass *child_class,
+                         BdrvChildRole child_role,
+                         Transaction *tran,
+                         Error **errp)
 {
     uint64_t perm, shared_perm;
 
@@ -3167,6 +3167,8 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
 
     GLOBAL_STATE_CODE();
 
+    bdrv_graph_wrlock(child_bs);
+
     child = bdrv_attach_child_common(child_bs, child_name, child_class,
                                    child_role, perm, shared_perm, opaque,
                                    tran, errp);
@@ -3178,6 +3180,7 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
     ret = bdrv_refresh_perms(child_bs, tran, errp);
 
 out:
+    bdrv_graph_wrunlock();
     tran_finalize(tran, ret);
 
     bdrv_unref(child_bs);
@@ -3209,6 +3212,8 @@ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
 
     GLOBAL_STATE_CODE();
 
+    bdrv_graph_wrlock(child_bs);
+
     child = bdrv_attach_child_noperm(parent_bs, child_bs, child_name,
                                      child_class, child_role, tran, errp);
     if (!child) {
@@ -3222,6 +3227,7 @@ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
     }
 
 out:
+    bdrv_graph_wrunlock();
     tran_finalize(tran, ret);
 
     bdrv_unref(child_bs);
@@ -3379,16 +3385,20 @@ static BdrvChildRole bdrv_backing_role(BlockDriverState *bs)
  * Sets the bs->backing or bs->file link of a BDS. A new reference is created;
  * callers which don't need their own reference any more must call bdrv_unref().
  *
+ * If the respective child is already present (i.e. we're detaching a node),
+ * that child node must be drained.
+ *
  * Function doesn't update permissions, caller is responsible for this.
  *
  * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
  * @child_bs can move to a different AioContext in this function. Callers must
  * make sure that their AioContext locking is still correct after this.
  */
-static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
-                                           BlockDriverState *child_bs,
-                                           bool is_backing,
-                                           Transaction *tran, Error **errp)
+static int GRAPH_WRLOCK
+bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
+                                BlockDriverState *child_bs,
+                                bool is_backing,
+                                Transaction *tran, Error **errp)
 {
     bool update_inherits_from =
         bdrv_inherits_from_recursive(child_bs, parent_bs);
@@ -3439,14 +3449,9 @@ static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
     }
 
     if (child) {
-        bdrv_drained_begin(child->bs);
-        bdrv_graph_wrlock(NULL);
-
+        assert(child->bs->quiesce_counter);
         bdrv_unset_inherits_from(parent_bs, child, tran);
         bdrv_remove_child(child, tran);
-
-        bdrv_graph_wrunlock();
-        bdrv_drained_end(child->bs);
     }
 
     if (!child_bs) {
@@ -3471,9 +3476,7 @@ static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
     }
 
 out:
-    bdrv_graph_rdlock_main_loop();
     bdrv_refresh_limits(parent_bs, tran, NULL);
-    bdrv_graph_rdunlock_main_loop();
 
     return 0;
 }
@@ -3482,10 +3485,14 @@ out:
  * The caller must hold the AioContext lock for @backing_hd. Both @bs and
  * @backing_hd can move to a different AioContext in this function. Callers must
  * make sure that their AioContext locking is still correct after this.
+ *
+ * If a backing child is already present (i.e. we're detaching a node), that
+ * child node must be drained.
  */
-static int bdrv_set_backing_noperm(BlockDriverState *bs,
-                                   BlockDriverState *backing_hd,
-                                   Transaction *tran, Error **errp)
+static int GRAPH_WRLOCK
+bdrv_set_backing_noperm(BlockDriverState *bs,
+                        BlockDriverState *backing_hd,
+                        Transaction *tran, Error **errp)
 {
     GLOBAL_STATE_CODE();
     return bdrv_set_file_or_backing_noperm(bs, backing_hd, true, tran, errp);
@@ -3500,6 +3507,10 @@ int bdrv_set_backing_hd_drained(BlockDriverState *bs,
 
     GLOBAL_STATE_CODE();
     assert(bs->quiesce_counter > 0);
+    if (bs->backing) {
+        assert(bs->backing->bs->quiesce_counter > 0);
+    }
+    bdrv_graph_wrlock(backing_hd);
 
     ret = bdrv_set_backing_noperm(bs, backing_hd, tran, errp);
     if (ret < 0) {
@@ -3508,6 +3519,7 @@ int bdrv_set_backing_hd_drained(BlockDriverState *bs,
 
     ret = bdrv_refresh_perms(bs, tran, errp);
 out:
+    bdrv_graph_wrunlock();
     tran_finalize(tran, ret);
     return ret;
 }
@@ -3515,12 +3527,15 @@ out:
 int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
                         Error **errp)
 {
+    BlockDriverState *drain_bs = bs->backing ? bs->backing->bs : bs;
     int ret;
     GLOBAL_STATE_CODE();
 
-    bdrv_drained_begin(bs);
+    bdrv_ref(drain_bs);
+    bdrv_drained_begin(drain_bs);
     ret = bdrv_set_backing_hd_drained(bs, backing_hd, errp);
-    bdrv_drained_end(bs);
+    bdrv_drained_end(drain_bs);
+    bdrv_unref(drain_bs);
 
     return ret;
 }
@@ -4597,6 +4612,7 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
 
 abort:
     tran_abort(tran);
+
     QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
         if (bs_entry->prepared) {
             ctx = bdrv_get_aio_context(bs_entry->state.bs);
@@ -4746,6 +4762,11 @@ static int bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state,
         reopen_state->old_file_bs = old_child_bs;
     }
 
+    if (old_child_bs) {
+        bdrv_ref(old_child_bs);
+        bdrv_drained_begin(old_child_bs);
+    }
+
     old_ctx = bdrv_get_aio_context(bs);
     ctx = bdrv_get_aio_context(new_child_bs);
     if (old_ctx != ctx) {
@@ -4753,14 +4774,23 @@ static int bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state,
         aio_context_acquire(ctx);
     }
 
+    bdrv_graph_wrlock(new_child_bs);
+
     ret = bdrv_set_file_or_backing_noperm(bs, new_child_bs, is_backing,
                                           tran, errp);
 
+    bdrv_graph_wrunlock();
+
     if (old_ctx != ctx) {
         aio_context_release(ctx);
         aio_context_acquire(old_ctx);
     }
 
+    if (old_child_bs) {
+        bdrv_drained_end(old_child_bs);
+        bdrv_unref(old_child_bs);
+    }
+
     return ret;
 }
 
@@ -5403,13 +5433,28 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
     BdrvChild *child;
     Transaction *tran = tran_new();
     AioContext *old_context, *new_context = NULL;
-    bool drained = false;
 
     GLOBAL_STATE_CODE();
 
     assert(!bs_new->backing);
 
     old_context = bdrv_get_aio_context(bs_top);
+    bdrv_drained_begin(bs_top);
+
+    /*
+     * bdrv_drained_begin() requires that only the AioContext of the drained
+     * node is locked, and at this point it can still differ from the AioContext
+     * of bs_top.
+     */
+    new_context = bdrv_get_aio_context(bs_new);
+    aio_context_release(old_context);
+    aio_context_acquire(new_context);
+    bdrv_drained_begin(bs_new);
+    aio_context_release(new_context);
+    aio_context_acquire(old_context);
+    new_context = NULL;
+
+    bdrv_graph_wrlock(bs_top);
 
     child = bdrv_attach_child_noperm(bs_new, bs_top, "backing",
                                      &child_of_bds, bdrv_backing_role(bs_new),
@@ -5420,10 +5465,9 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
     }
 
     /*
-     * bdrv_attach_child_noperm could change the AioContext of bs_top.
-     * bdrv_replace_node_noperm calls bdrv_drained_begin, so let's temporarily
-     * hold the new AioContext, since bdrv_drained_begin calls BDRV_POLL_WHILE
-     * that assumes the new lock is taken.
+     * bdrv_attach_child_noperm could change the AioContext of bs_top and
+     * bs_new, but at least they are in the same AioContext now. This is the
+     * AioContext that we need to lock for the rest of the function.
      */
     new_context = bdrv_get_aio_context(bs_top);
 
@@ -5432,29 +5476,22 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
         aio_context_acquire(new_context);
     }
 
-    bdrv_drained_begin(bs_new);
-    bdrv_drained_begin(bs_top);
-    drained = true;
-
-    bdrv_graph_wrlock(bs_new);
     ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp);
-    bdrv_graph_wrunlock();
     if (ret < 0) {
         goto out;
     }
 
     ret = bdrv_refresh_perms(bs_new, tran, errp);
 out:
+    bdrv_graph_wrunlock();
     tran_finalize(tran, ret);
 
     bdrv_graph_rdlock_main_loop();
     bdrv_refresh_limits(bs_top, NULL, NULL);
     bdrv_graph_rdunlock_main_loop();
 
-    if (drained) {
-        bdrv_drained_end(bs_top);
-        bdrv_drained_end(bs_new);
-    }
+    bdrv_drained_end(bs_top);
+    bdrv_drained_end(bs_new);
 
     if (new_context && old_context != new_context) {
         aio_context_release(new_context);
diff --git a/block/stream.c b/block/stream.c
index e522bbdec5..e4da214f1f 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -54,6 +54,7 @@ static int stream_prepare(Job *job)
 {
     StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
     BlockDriverState *unfiltered_bs = bdrv_skip_filters(s->target_bs);
+    BlockDriverState *unfiltered_bs_cow = bdrv_cow_bs(unfiltered_bs);
     BlockDriverState *base;
     BlockDriverState *unfiltered_base;
     Error *local_err = NULL;
@@ -64,13 +65,18 @@ static int stream_prepare(Job *job)
     s->cor_filter_bs = NULL;
 
     /*
-     * bdrv_set_backing_hd() requires that unfiltered_bs is drained. Drain
-     * already here and use bdrv_set_backing_hd_drained() instead because
-     * the polling during drained_begin() might change the graph, and if we do
-     * this only later, we may end up working with the wrong base node (or it
-     * might even have gone away by the time we want to use it).
+     * bdrv_set_backing_hd() requires that the unfiltered_bs and the COW child
+     * of unfiltered_bs is drained. Drain already here and use
+     * bdrv_set_backing_hd_drained() instead because the polling during
+     * drained_begin() might change the graph, and if we do this only later, we
+     * may end up working with the wrong base node (or it might even have gone
+     * away by the time we want to use it).
      */
     bdrv_drained_begin(unfiltered_bs);
+    if (unfiltered_bs_cow) {
+        bdrv_ref(unfiltered_bs_cow);
+        bdrv_drained_begin(unfiltered_bs_cow);
+    }
 
     base = bdrv_filter_or_cow_bs(s->above_base);
     unfiltered_base = bdrv_skip_filters(base);
@@ -100,6 +106,10 @@ static int stream_prepare(Job *job)
     }
 
 out:
+    if (unfiltered_bs_cow) {
+        bdrv_drained_end(unfiltered_bs_cow);
+        bdrv_unref(unfiltered_bs_cow);
+    }
     bdrv_drained_end(unfiltered_bs);
     return ret;
 }
-- 
2.41.0

[PULL 11/28] block: Call transaction callbacks with lock held

[Kevin Wolf]

In previous patches, we changed some transactionable functions to be
marked as GRAPH_WRLOCK, but required that tran_finalize() is still
called without the lock. This was because all callbacks that can be in
the same transaction need to follow the same convention.

Now that we don't have conflicting requirements any more, we can switch
all of the transaction callbacks to be declared GRAPH_WRLOCK, too, and
call tran_finalize() with the lock held.

Document for each of these transactionable functions that the lock needs
to be held when completing the transaction, and make sure that all
callers down to the place where the transaction is finalised actually
have the writer lock.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-12-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 61 +++++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 44 insertions(+), 17 deletions(-)

diff --git a/block.c b/block.c
index f6e7cf4fb9..f06de58a3b 100644
--- a/block.c
+++ b/block.c
@@ -2375,21 +2375,21 @@ typedef struct BdrvReplaceChildState {
     BlockDriverState *old_bs;
 } BdrvReplaceChildState;
 
-static void bdrv_replace_child_commit(void *opaque)
+static void GRAPH_WRLOCK bdrv_replace_child_commit(void *opaque)
 {
     BdrvReplaceChildState *s = opaque;
     GLOBAL_STATE_CODE();
 
-    bdrv_unref(s->old_bs);
+    bdrv_schedule_unref(s->old_bs);
 }
 
-static void bdrv_replace_child_abort(void *opaque)
+static void GRAPH_WRLOCK bdrv_replace_child_abort(void *opaque)
 {
     BdrvReplaceChildState *s = opaque;
     BlockDriverState *new_bs = s->child->bs;
 
     GLOBAL_STATE_CODE();
-    bdrv_graph_wrlock(s->old_bs);
+    assert_bdrv_graph_writable();
 
     /* old_bs reference is transparently moved from @s to @s->child */
     if (!s->child->bs) {
@@ -2408,7 +2408,6 @@ static void bdrv_replace_child_abort(void *opaque)
     assert(s->child->quiesced_parent);
     bdrv_replace_child_noperm(s->child, s->old_bs);
 
-    bdrv_graph_wrunlock();
     bdrv_unref(new_bs);
 }
 
@@ -2426,6 +2425,9 @@ static TransactionActionDrv bdrv_replace_child_drv = {
  * Both @child->bs and @new_bs (if non-NULL) must be drained. @new_bs must be
  * kept drained until the transaction is completed.
  *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a writer lock for the graph.
+ *
  * The function doesn't update permissions, caller is responsible for this.
  */
 static void GRAPH_WRLOCK
@@ -2951,16 +2953,15 @@ typedef struct BdrvAttachChildCommonState {
     AioContext *old_child_ctx;
 } BdrvAttachChildCommonState;
 
-static void bdrv_attach_child_common_abort(void *opaque)
+static void GRAPH_WRLOCK bdrv_attach_child_common_abort(void *opaque)
 {
     BdrvAttachChildCommonState *s = opaque;
     BlockDriverState *bs = s->child->bs;
 
     GLOBAL_STATE_CODE();
+    assert_bdrv_graph_writable();
 
-    bdrv_graph_wrlock(NULL);
     bdrv_replace_child_noperm(s->child, NULL);
-    bdrv_graph_wrunlock();
 
     if (bdrv_get_aio_context(bs) != s->old_child_ctx) {
         bdrv_try_change_aio_context(bs, s->old_child_ctx, NULL, &error_abort);
@@ -2984,7 +2985,7 @@ static void bdrv_attach_child_common_abort(void *opaque)
         tran_commit(tran);
     }
 
-    bdrv_unref(bs);
+    bdrv_schedule_unref(bs);
     bdrv_child_free(s->child);
 }
 
@@ -2998,6 +2999,9 @@ static TransactionActionDrv bdrv_attach_child_common_drv = {
  *
  * Function doesn't update permissions, caller is responsible for this.
  *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a writer lock for the graph.
+ *
  * Returns new created child.
  *
  * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
@@ -3114,6 +3118,9 @@ bdrv_attach_child_common(BlockDriverState *child_bs,
  * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
  * @child_bs can move to a different AioContext in this function. Callers must
  * make sure that their AioContext locking is still correct after this.
+ *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a writer lock for the graph.
  */
 static BdrvChild * GRAPH_WRLOCK
 bdrv_attach_child_noperm(BlockDriverState *parent_bs,
@@ -3180,8 +3187,8 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
     ret = bdrv_refresh_perms(child_bs, tran, errp);
 
 out:
-    bdrv_graph_wrunlock();
     tran_finalize(tran, ret);
+    bdrv_graph_wrunlock();
 
     bdrv_unref(child_bs);
 
@@ -3227,8 +3234,8 @@ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
     }
 
 out:
-    bdrv_graph_wrunlock();
     tran_finalize(tran, ret);
+    bdrv_graph_wrunlock();
 
     bdrv_unref(child_bs);
 
@@ -3393,6 +3400,9 @@ static BdrvChildRole bdrv_backing_role(BlockDriverState *bs)
  * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
  * @child_bs can move to a different AioContext in this function. Callers must
  * make sure that their AioContext locking is still correct after this.
+ *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a writer lock for the graph.
  */
 static int GRAPH_WRLOCK
 bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
@@ -3488,6 +3498,9 @@ out:
  *
  * If a backing child is already present (i.e. we're detaching a node), that
  * child node must be drained.
+ *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a writer lock for the graph.
  */
 static int GRAPH_WRLOCK
 bdrv_set_backing_noperm(BlockDriverState *bs,
@@ -3519,8 +3532,8 @@ int bdrv_set_backing_hd_drained(BlockDriverState *bs,
 
     ret = bdrv_refresh_perms(bs, tran, errp);
 out:
-    bdrv_graph_wrunlock();
     tran_finalize(tran, ret);
+    bdrv_graph_wrunlock();
     return ret;
 }
 
@@ -4594,7 +4607,9 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
         aio_context_release(ctx);
     }
 
+    bdrv_graph_wrlock(NULL);
     tran_commit(tran);
+    bdrv_graph_wrunlock();
 
     QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
         BlockDriverState *bs = bs_entry->state.bs;
@@ -4611,7 +4626,9 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
     goto cleanup;
 
 abort:
+    bdrv_graph_wrlock(NULL);
     tran_abort(tran);
+    bdrv_graph_wrunlock();
 
     QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
         if (bs_entry->prepared) {
@@ -4678,6 +4695,9 @@ int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only,
  * true and reopen_state->new_backing_bs contains a pointer to the new
  * backing BlockDriverState (or NULL).
  *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a writer lock for the graph.
+ *
  * Return 0 on success, otherwise return < 0 and set @errp.
  *
  * The caller must hold the AioContext lock of @reopen_state->bs.
@@ -4811,6 +4831,9 @@ static int bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state,
  * commit() for any other BDS that have been left in a prepare() state
  *
  * The caller must hold the AioContext lock of @reopen_state->bs.
+ *
+ * After calling this function, the transaction @change_child_tran may only be
+ * completed while holding a writer lock for the graph.
  */
 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
                                BlockReopenQueue *queue,
@@ -5262,6 +5285,9 @@ static TransactionActionDrv bdrv_remove_child_drv = {
  * Function doesn't update permissions, caller is responsible for this.
  *
  * @child->bs (if non-NULL) must be drained.
+ *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a writer lock for the graph.
  */
 static void GRAPH_WRLOCK bdrv_remove_child(BdrvChild *child, Transaction *tran)
 {
@@ -5280,6 +5306,9 @@ static void GRAPH_WRLOCK bdrv_remove_child(BdrvChild *child, Transaction *tran)
 /*
  * Both @from and @to (if non-NULL) must be drained. @to must be kept drained
  * until the transaction is completed.
+ *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a writer lock for the graph.
  */
 static int GRAPH_WRLOCK
 bdrv_replace_node_noperm(BlockDriverState *from,
@@ -5386,8 +5415,8 @@ static int bdrv_replace_node_common(BlockDriverState *from,
     ret = 0;
 
 out:
-    bdrv_graph_wrunlock();
     tran_finalize(tran, ret);
+    bdrv_graph_wrunlock();
 
     bdrv_drained_end(to);
     bdrv_drained_end(from);
@@ -5483,12 +5512,10 @@ int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
 
     ret = bdrv_refresh_perms(bs_new, tran, errp);
 out:
-    bdrv_graph_wrunlock();
     tran_finalize(tran, ret);
 
-    bdrv_graph_rdlock_main_loop();
     bdrv_refresh_limits(bs_top, NULL, NULL);
-    bdrv_graph_rdunlock_main_loop();
+    bdrv_graph_wrunlock();
 
     bdrv_drained_end(bs_top);
     bdrv_drained_end(bs_new);
@@ -5523,10 +5550,10 @@ int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs,
     refresh_list = g_slist_prepend(refresh_list, new_bs);
 
     ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp);
-    bdrv_graph_wrunlock();
 
     tran_finalize(tran, ret);
 
+    bdrv_graph_wrunlock();
     bdrv_drained_end(old_bs);
     bdrv_drained_end(new_bs);
     bdrv_unref(old_bs);
-- 
2.41.0

[PULL 12/28] block: Mark bdrv_attach_child() GRAPH_WRLOCK

[Kevin Wolf]

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_attach_child_common(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-13-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-global-state.h | 14 ++++++++------
 block.c                            |  7 +++----
 block/quorum.c                     |  2 ++
 block/replication.c                |  6 ++++++
 tests/unit/test-bdrv-drain.c       | 14 ++++++++++++++
 tests/unit/test-bdrv-graph-mod.c   | 10 ++++++++++
 6 files changed, 43 insertions(+), 10 deletions(-)

diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index e570799f85..eb12a35439 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -226,12 +226,14 @@ void no_coroutine_fn bdrv_unref(BlockDriverState *bs);
 void coroutine_fn no_co_wrapper bdrv_co_unref(BlockDriverState *bs);
 void GRAPH_WRLOCK bdrv_schedule_unref(BlockDriverState *bs);
 void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child);
-BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
-                             BlockDriverState *child_bs,
-                             const char *child_name,
-                             const BdrvChildClass *child_class,
-                             BdrvChildRole child_role,
-                             Error **errp);
+
+BdrvChild * GRAPH_WRLOCK
+bdrv_attach_child(BlockDriverState *parent_bs,
+                  BlockDriverState *child_bs,
+                  const char *child_name,
+                  const BdrvChildClass *child_class,
+                  BdrvChildRole child_role,
+                  Error **errp);
 
 bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp);
 void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason);
diff --git a/block.c b/block.c
index f06de58a3b..369023872a 100644
--- a/block.c
+++ b/block.c
@@ -3219,8 +3219,6 @@ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
 
     GLOBAL_STATE_CODE();
 
-    bdrv_graph_wrlock(child_bs);
-
     child = bdrv_attach_child_noperm(parent_bs, child_bs, child_name,
                                      child_class, child_role, tran, errp);
     if (!child) {
@@ -3235,9 +3233,8 @@ BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
 
 out:
     tran_finalize(tran, ret);
-    bdrv_graph_wrunlock();
 
-    bdrv_unref(child_bs);
+    bdrv_schedule_unref(child_bs);
 
     return ret < 0 ? NULL : child;
 }
@@ -3758,11 +3755,13 @@ BdrvChild *bdrv_open_child(const char *filename,
         return NULL;
     }
 
+    bdrv_graph_wrlock(NULL);
     ctx = bdrv_get_aio_context(bs);
     aio_context_acquire(ctx);
     child = bdrv_attach_child(parent, bs, bdref_key, child_class, child_role,
                               errp);
     aio_context_release(ctx);
+    bdrv_graph_wrunlock();
 
     return child;
 }
diff --git a/block/quorum.c b/block/quorum.c
index f28758cf2b..def0539fda 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1094,8 +1094,10 @@ static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs,
     /* We can safely add the child now */
     bdrv_ref(child_bs);
 
+    bdrv_graph_wrlock(child_bs);
     child = bdrv_attach_child(bs, child_bs, indexstr, &child_of_bds,
                               BDRV_CHILD_DATA, errp);
+    bdrv_graph_wrunlock();
     if (child == NULL) {
         s->next_child_index--;
         goto out;
diff --git a/block/replication.c b/block/replication.c
index ea4bf1aa80..eec9819625 100644
--- a/block/replication.c
+++ b/block/replication.c
@@ -542,12 +542,15 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
             return;
         }
 
+        bdrv_graph_wrlock(bs);
+
         bdrv_ref(hidden_disk->bs);
         s->hidden_disk = bdrv_attach_child(bs, hidden_disk->bs, "hidden disk",
                                            &child_of_bds, BDRV_CHILD_DATA,
                                            &local_err);
         if (local_err) {
             error_propagate(errp, local_err);
+            bdrv_graph_wrunlock();
             aio_context_release(aio_context);
             return;
         }
@@ -558,10 +561,13 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
                                               BDRV_CHILD_DATA, &local_err);
         if (local_err) {
             error_propagate(errp, local_err);
+            bdrv_graph_wrunlock();
             aio_context_release(aio_context);
             return;
         }
 
+        bdrv_graph_wrunlock();
+
         /* start backup job now */
         error_setg(&s->blocker,
                    "Block device is in use by internal backup job");
diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index 89c8fa6780..6d33249656 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -1055,8 +1055,10 @@ static void do_test_delete_by_drain(bool detach_instead_of_delete,
 
     null_bs = bdrv_open("null-co://", NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
                         &error_abort);
+    bdrv_graph_wrlock(NULL);
     bdrv_attach_child(bs, null_bs, "null-child", &child_of_bds,
                       BDRV_CHILD_DATA, &error_abort);
+    bdrv_graph_wrunlock();
 
     /* This child will be the one to pass to requests through to, and
      * it will stall until a drain occurs */
@@ -1064,17 +1066,21 @@ static void do_test_delete_by_drain(bool detach_instead_of_delete,
                                     &error_abort);
     child_bs->total_sectors = 65536 >> BDRV_SECTOR_BITS;
     /* Takes our reference to child_bs */
+    bdrv_graph_wrlock(NULL);
     tts->wait_child = bdrv_attach_child(bs, child_bs, "wait-child",
                                         &child_of_bds,
                                         BDRV_CHILD_DATA | BDRV_CHILD_PRIMARY,
                                         &error_abort);
+    bdrv_graph_wrunlock();
 
     /* This child is just there to be deleted
      * (for detach_instead_of_delete == true) */
     null_bs = bdrv_open("null-co://", NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
                         &error_abort);
+    bdrv_graph_wrlock(NULL);
     bdrv_attach_child(bs, null_bs, "null-child", &child_of_bds, BDRV_CHILD_DATA,
                       &error_abort);
+    bdrv_graph_wrunlock();
 
     blk = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
     blk_insert_bs(blk, bs, &error_abort);
@@ -1159,9 +1165,11 @@ static void detach_indirect_bh(void *opaque)
     bdrv_unref_child(data->parent_b, data->child_b);
 
     bdrv_ref(data->c);
+    bdrv_graph_wrlock(NULL);
     data->child_c = bdrv_attach_child(data->parent_b, data->c, "PB-C",
                                       &child_of_bds, BDRV_CHILD_DATA,
                                       &error_abort);
+    bdrv_graph_wrunlock();
 }
 
 static void detach_by_parent_aio_cb(void *opaque, int ret)
@@ -1258,6 +1266,7 @@ static void test_detach_indirect(bool by_parent_cb)
     /* Set child relationships */
     bdrv_ref(b);
     bdrv_ref(a);
+    bdrv_graph_wrlock(NULL);
     child_b = bdrv_attach_child(parent_b, b, "PB-B", &child_of_bds,
                                 BDRV_CHILD_DATA, &error_abort);
     child_a = bdrv_attach_child(parent_b, a, "PB-A", &child_of_bds,
@@ -1267,6 +1276,7 @@ static void test_detach_indirect(bool by_parent_cb)
     bdrv_attach_child(parent_a, a, "PA-A",
                       by_parent_cb ? &child_of_bds : &detach_by_driver_cb_class,
                       BDRV_CHILD_DATA, &error_abort);
+    bdrv_graph_wrunlock();
 
     g_assert_cmpint(parent_a->refcnt, ==, 1);
     g_assert_cmpint(parent_b->refcnt, ==, 1);
@@ -1685,6 +1695,7 @@ static void test_drop_intermediate_poll(void)
      * Establish the chain last, so the chain links are the first
      * elements in the BDS.parents lists
      */
+    bdrv_graph_wrlock(NULL);
     for (i = 0; i < 3; i++) {
         if (i) {
             /* Takes the reference to chain[i - 1] */
@@ -1692,6 +1703,7 @@ static void test_drop_intermediate_poll(void)
                               &chain_child_class, BDRV_CHILD_COW, &error_abort);
         }
     }
+    bdrv_graph_wrunlock();
 
     job = block_job_create("job", &test_simple_job_driver, NULL, job_node,
                            0, BLK_PERM_ALL, 0, 0, NULL, NULL, &error_abort);
@@ -1936,8 +1948,10 @@ static void do_test_replace_child_mid_drain(int old_drain_count,
     new_child_bs->total_sectors = 1;
 
     bdrv_ref(old_child_bs);
+    bdrv_graph_wrlock(NULL);
     bdrv_attach_child(parent_bs, old_child_bs, "child", &child_of_bds,
                       BDRV_CHILD_COW, &error_abort);
+    bdrv_graph_wrunlock();
     parent_s->setup_completed = true;
 
     for (i = 0; i < old_drain_count; i++) {
diff --git a/tests/unit/test-bdrv-graph-mod.c b/tests/unit/test-bdrv-graph-mod.c
index d8503165b3..621e616655 100644
--- a/tests/unit/test-bdrv-graph-mod.c
+++ b/tests/unit/test-bdrv-graph-mod.c
@@ -137,8 +137,10 @@ static void test_update_perm_tree(void)
 
     blk_insert_bs(root, bs, &error_abort);
 
+    bdrv_graph_wrlock(NULL);
     bdrv_attach_child(filter, bs, "child", &child_of_bds,
                       BDRV_CHILD_DATA, &error_abort);
+    bdrv_graph_wrunlock();
 
     aio_context_acquire(qemu_get_aio_context());
     ret = bdrv_append(filter, bs, NULL);
@@ -205,8 +207,10 @@ static void test_should_update_child(void)
     bdrv_set_backing_hd(target, bs, &error_abort);
 
     g_assert(target->backing->bs == bs);
+    bdrv_graph_wrlock(NULL);
     bdrv_attach_child(filter, target, "target", &child_of_bds,
                       BDRV_CHILD_DATA, &error_abort);
+    bdrv_graph_wrunlock();
     aio_context_acquire(qemu_get_aio_context());
     bdrv_append(filter, bs, &error_abort);
     aio_context_release(qemu_get_aio_context());
@@ -236,6 +240,7 @@ static void test_parallel_exclusive_write(void)
      */
     bdrv_ref(base);
 
+    bdrv_graph_wrlock(NULL);
     bdrv_attach_child(top, fl1, "backing", &child_of_bds,
                       BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
                       &error_abort);
@@ -245,6 +250,7 @@ static void test_parallel_exclusive_write(void)
     bdrv_attach_child(fl2, base, "backing", &child_of_bds,
                       BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
                       &error_abort);
+    bdrv_graph_wrunlock();
 
     bdrv_replace_node(fl1, fl2, &error_abort);
 
@@ -349,6 +355,7 @@ static void test_parallel_perm_update(void)
      */
     bdrv_ref(base);
 
+    bdrv_graph_wrlock(NULL);
     bdrv_attach_child(top, ws, "file", &child_of_bds, BDRV_CHILD_DATA,
                       &error_abort);
     c_fl1 = bdrv_attach_child(ws, fl1, "first", &child_of_bds,
@@ -361,6 +368,7 @@ static void test_parallel_perm_update(void)
     bdrv_attach_child(fl2, base, "backing", &child_of_bds,
                       BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
                       &error_abort);
+    bdrv_graph_wrunlock();
 
     /* Select fl1 as first child to be active */
     s->selected = c_fl1;
@@ -410,9 +418,11 @@ static void test_append_greedy_filter(void)
     BlockDriverState *base = no_perm_node("base");
     BlockDriverState *fl = exclusive_writer_node("fl1");
 
+    bdrv_graph_wrlock(NULL);
     bdrv_attach_child(top, base, "backing", &child_of_bds,
                       BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
                       &error_abort);
+    bdrv_graph_wrunlock();
 
     aio_context_acquire(qemu_get_aio_context());
     bdrv_append(fl, base, &error_abort);
-- 
2.41.0

[PULL 13/28] block: Mark bdrv_parent_perms_conflict() and callers GRAPH_RDLOCK

[Kevin Wolf]

The function reads the parents list, so it needs to hold the graph lock.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-14-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block_int-common.h            |  6 ++---
 include/block/block_int-global-state.h      |  8 +++---
 include/sysemu/block-backend-global-state.h |  4 +--
 block.c                                     | 28 +++++++++++++--------
 block/block-backend.c                       | 26 ++++++++++++++-----
 block/crypto.c                              |  6 +++--
 block/mirror.c                              |  8 ++++++
 block/vmdk.c                                |  2 ++
 tests/unit/test-bdrv-graph-mod.c            |  4 +++
 9 files changed, 66 insertions(+), 26 deletions(-)

diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 85be256c09..fda9d8b5c8 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -311,7 +311,7 @@ struct BlockDriver {
      */
     void (*bdrv_cancel_in_flight)(BlockDriverState *bs);
 
-    int (*bdrv_inactivate)(BlockDriverState *bs);
+    int GRAPH_RDLOCK_PTR (*bdrv_inactivate)(BlockDriverState *bs);
 
     int (*bdrv_snapshot_create)(BlockDriverState *bs,
                                 QEMUSnapshotInfo *sn_info);
@@ -944,8 +944,8 @@ struct BdrvChildClass {
      * when migration is completing) and it can start/stop requesting
      * permissions and doing I/O on it.
      */
-    void (*activate)(BdrvChild *child, Error **errp);
-    int (*inactivate)(BdrvChild *child);
+    void GRAPH_RDLOCK_PTR (*activate)(BdrvChild *child, Error **errp);
+    int GRAPH_RDLOCK_PTR (*inactivate)(BdrvChild *child);
 
     void GRAPH_WRLOCK_PTR (*attach)(BdrvChild *child);
     void GRAPH_WRLOCK_PTR (*detach)(BdrvChild *child);
diff --git a/include/block/block_int-global-state.h b/include/block/block_int-global-state.h
index da5fb31089..bebcc08bce 100644
--- a/include/block/block_int-global-state.h
+++ b/include/block/block_int-global-state.h
@@ -212,8 +212,9 @@ void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
  * bdrv_child_refresh_perms() instead and make the parent's
  * .bdrv_child_perm() implementation return the correct values.
  */
-int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
-                            Error **errp);
+int GRAPH_RDLOCK
+bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
+                        Error **errp);
 
 /**
  * Calls bs->drv->bdrv_child_perm() and updates the child's permission
@@ -223,7 +224,8 @@ int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
  * values than before, but which will not result in the block layer
  * automatically refreshing the permissions.
  */
-int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp);
+int GRAPH_RDLOCK
+bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp);
 
 bool GRAPH_RDLOCK bdrv_recurse_can_replace(BlockDriverState *bs,
                                            BlockDriverState *to_replace);
diff --git a/include/sysemu/block-backend-global-state.h b/include/sysemu/block-backend-global-state.h
index 184e667ebd..d5f675493a 100644
--- a/include/sysemu/block-backend-global-state.h
+++ b/include/sysemu/block-backend-global-state.h
@@ -61,8 +61,8 @@ int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp);
 int blk_replace_bs(BlockBackend *blk, BlockDriverState *new_bs, Error **errp);
 bool bdrv_has_blk(BlockDriverState *bs);
 bool bdrv_is_root_node(BlockDriverState *bs);
-int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
-                 Error **errp);
+int GRAPH_UNLOCKED blk_set_perm(BlockBackend *blk, uint64_t perm,
+                                uint64_t shared_perm, Error **errp);
 void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm);
 
 void blk_iostatus_enable(BlockBackend *blk);
diff --git a/block.c b/block.c
index 369023872a..6720bc4f8a 100644
--- a/block.c
+++ b/block.c
@@ -2202,7 +2202,8 @@ static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp)
     return false;
 }
 
-static bool bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp)
+static bool GRAPH_RDLOCK
+bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp)
 {
     BdrvChild *a, *b;
     GLOBAL_STATE_CODE();
@@ -2255,8 +2256,8 @@ static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
  * simplest way to satisfy this criteria: use only result of
  * bdrv_topological_dfs() or NULL as @list parameter.
  */
-static GSList *bdrv_topological_dfs(GSList *list, GHashTable *found,
-                                    BlockDriverState *bs)
+static GSList * GRAPH_RDLOCK
+bdrv_topological_dfs(GSList *list, GHashTable *found, BlockDriverState *bs)
 {
     BdrvChild *child;
     g_autoptr(GHashTable) local_found = NULL;
@@ -2532,8 +2533,9 @@ static int bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
  * @list is a product of bdrv_topological_dfs() (may be called several times) -
  * a topologically sorted subgraph.
  */
-static int bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q,
-                                 Transaction *tran, Error **errp)
+static int GRAPH_RDLOCK
+bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
+                      Error **errp)
 {
     int ret;
     BlockDriverState *bs;
@@ -2560,8 +2562,9 @@ static int bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q,
  * topologically sorted. It's not a problem if some node occurs in the @list
  * several times.
  */
-static int bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q,
-                                   Transaction *tran, Error **errp)
+static int GRAPH_RDLOCK
+bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
+                        Error **errp)
 {
     g_autoptr(GHashTable) found = g_hash_table_new(NULL, NULL);
     g_autoptr(GSList) refresh_list = NULL;
@@ -2621,8 +2624,8 @@ char *bdrv_perm_names(uint64_t perm)
 
 
 /* @tran is allowed to be NULL. In this case no rollback is possible */
-static int bdrv_refresh_perms(BlockDriverState *bs, Transaction *tran,
-                              Error **errp)
+static int GRAPH_RDLOCK
+bdrv_refresh_perms(BlockDriverState *bs, Transaction *tran, Error **errp)
 {
     int ret;
     Transaction *local_tran = NULL;
@@ -3247,7 +3250,6 @@ void bdrv_root_unref_child(BdrvChild *child)
     GLOBAL_STATE_CODE();
     bdrv_graph_wrlock(NULL);
     bdrv_replace_child_noperm(child, NULL);
-    bdrv_graph_wrunlock();
     bdrv_child_free(child);
 
     if (child_bs) {
@@ -3266,6 +3268,7 @@ void bdrv_root_unref_child(BdrvChild *child)
                                     NULL);
     }
 
+    bdrv_graph_wrunlock();
     bdrv_unref(child_bs);
 }
 
@@ -4585,7 +4588,10 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
      * reconfiguring the fd and that's why it does it in raw_check_perm(), not
      * in raw_reopen_prepare() which is called with "old" permissions.
      */
+    bdrv_graph_rdlock_main_loop();
     ret = bdrv_list_refresh_perms(refresh_list, bs_queue, tran, errp);
+    bdrv_graph_rdunlock_main_loop();
+
     if (ret < 0) {
         goto abort;
     }
@@ -6833,6 +6839,7 @@ int bdrv_activate(BlockDriverState *bs, Error **errp)
     BdrvDirtyBitmap *bm;
 
     GLOBAL_STATE_CODE();
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
 
     if (!bs->drv)  {
         return -ENOMEDIUM;
@@ -6963,6 +6970,7 @@ static int bdrv_inactivate_recurse(BlockDriverState *bs)
     uint64_t cumulative_perms, cumulative_shared_perms;
 
     GLOBAL_STATE_CODE();
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
 
     if (!bs->drv) {
         return -ENOMEDIUM;
diff --git a/block/block-backend.c b/block/block-backend.c
index 4009ed5fed..8d0282a5d9 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -121,6 +121,10 @@ static QTAILQ_HEAD(, BlockBackend) block_backends =
 static QTAILQ_HEAD(, BlockBackend) monitor_block_backends =
     QTAILQ_HEAD_INITIALIZER(monitor_block_backends);
 
+static int coroutine_mixed_fn GRAPH_RDLOCK
+blk_set_perm_locked(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
+                    Error **errp);
+
 static void blk_root_inherit_options(BdrvChildRole role, bool parent_is_format,
                                      int *child_flags, QDict *child_options,
                                      int parent_flags, QDict *parent_options)
@@ -186,7 +190,7 @@ static void blk_vm_state_changed(void *opaque, bool running, RunState state)
  *
  * If an error is returned, the VM cannot be allowed to be resumed.
  */
-static void blk_root_activate(BdrvChild *child, Error **errp)
+static void GRAPH_RDLOCK blk_root_activate(BdrvChild *child, Error **errp)
 {
     BlockBackend *blk = child->opaque;
     Error *local_err = NULL;
@@ -207,7 +211,7 @@ static void blk_root_activate(BdrvChild *child, Error **errp)
      */
     saved_shared_perm = blk->shared_perm;
 
-    blk_set_perm(blk, blk->perm, BLK_PERM_ALL, &local_err);
+    blk_set_perm_locked(blk, blk->perm, BLK_PERM_ALL, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         blk->disable_perm = true;
@@ -226,7 +230,7 @@ static void blk_root_activate(BdrvChild *child, Error **errp)
         return;
     }
 
-    blk_set_perm(blk, blk->perm, blk->shared_perm, &local_err);
+    blk_set_perm_locked(blk, blk->perm, blk->shared_perm, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         blk->disable_perm = true;
@@ -259,7 +263,7 @@ static bool blk_can_inactivate(BlockBackend *blk)
     return blk->force_allow_inactivate;
 }
 
-static int blk_root_inactivate(BdrvChild *child)
+static int GRAPH_RDLOCK blk_root_inactivate(BdrvChild *child)
 {
     BlockBackend *blk = child->opaque;
 
@@ -953,8 +957,9 @@ int blk_replace_bs(BlockBackend *blk, BlockDriverState *new_bs, Error **errp)
 /*
  * Sets the permission bitmasks that the user of the BlockBackend needs.
  */
-int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
-                 Error **errp)
+static int coroutine_mixed_fn GRAPH_RDLOCK
+blk_set_perm_locked(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
+                    Error **errp)
 {
     int ret;
     GLOBAL_STATE_CODE();
@@ -972,6 +977,15 @@ int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
     return 0;
 }
 
+int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
+                 Error **errp)
+{
+    GLOBAL_STATE_CODE();
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
+
+    return blk_set_perm_locked(blk, perm, shared_perm, errp);
+}
+
 void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm)
 {
     GLOBAL_STATE_CODE();
diff --git a/block/crypto.c b/block/crypto.c
index 6ee8d46d30..c9c9a39fa3 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -777,7 +777,7 @@ block_crypto_get_specific_info_luks(BlockDriverState *bs, Error **errp)
     return spec_info;
 }
 
-static int
+static int GRAPH_RDLOCK
 block_crypto_amend_prepare(BlockDriverState *bs, Error **errp)
 {
     BlockCrypto *crypto = bs->opaque;
@@ -793,7 +793,7 @@ block_crypto_amend_prepare(BlockDriverState *bs, Error **errp)
     return ret;
 }
 
-static void
+static void GRAPH_RDLOCK
 block_crypto_amend_cleanup(BlockDriverState *bs)
 {
     BlockCrypto *crypto = bs->opaque;
@@ -841,6 +841,8 @@ block_crypto_amend_options_luks(BlockDriverState *bs,
     QCryptoBlockAmendOptions *amend_options = NULL;
     int ret = -EINVAL;
 
+    assume_graph_lock(); /* FIXME */
+
     assert(crypto);
     assert(crypto->block);
 
diff --git a/block/mirror.c b/block/mirror.c
index aae4bebbb6..3cc0757a03 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -702,8 +702,12 @@ static int mirror_exit_common(Job *job)
      * mirror_top_bs from now on, so keep it drained. */
     bdrv_drained_begin(mirror_top_bs);
     bs_opaque->stop = true;
+
+    bdrv_graph_rdlock_main_loop();
     bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing,
                              &error_abort);
+    bdrv_graph_rdunlock_main_loop();
+
     if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {
         BlockDriverState *backing = s->is_none_mode ? src : s->base;
         BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs);
@@ -1670,6 +1674,8 @@ static BlockJob *mirror_start_job(
     uint64_t target_perms, target_shared_perms;
     int ret;
 
+    GLOBAL_STATE_CODE();
+
     if (granularity == 0) {
         granularity = bdrv_get_default_bitmap_granularity(target);
     }
@@ -1906,8 +1912,10 @@ fail:
     }
 
     bs_opaque->stop = true;
+    bdrv_graph_rdlock_main_loop();
     bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing,
                              &error_abort);
+    bdrv_graph_rdunlock_main_loop();
     bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort);
 
     bdrv_unref(mirror_top_bs);
diff --git a/block/vmdk.c b/block/vmdk.c
index 58ce290e9c..84185b73a2 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1309,6 +1309,8 @@ static int vmdk_open(BlockDriverState *bs, QDict *options, int flags,
     BDRVVmdkState *s = bs->opaque;
     uint32_t magic;
 
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
+
     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
     if (ret < 0) {
         return ret;
diff --git a/tests/unit/test-bdrv-graph-mod.c b/tests/unit/test-bdrv-graph-mod.c
index 621e616655..8609f7f42b 100644
--- a/tests/unit/test-bdrv-graph-mod.c
+++ b/tests/unit/test-bdrv-graph-mod.c
@@ -372,6 +372,9 @@ static void test_parallel_perm_update(void)
 
     /* Select fl1 as first child to be active */
     s->selected = c_fl1;
+
+    bdrv_graph_rdlock_main_loop();
+
     bdrv_child_refresh_perms(top, top->children.lh_first, &error_abort);
 
     assert(c_fl1->perm & BLK_PERM_WRITE);
@@ -391,6 +394,7 @@ static void test_parallel_perm_update(void)
     assert(c_fl1->perm & BLK_PERM_WRITE);
     assert(!(c_fl2->perm & BLK_PERM_WRITE));
 
+    bdrv_graph_rdunlock_main_loop();
     bdrv_unref(top);
 }
 
-- 
2.41.0

[PULL 14/28] block: Mark bdrv_get_cumulative_perm() and callers GRAPH_RDLOCK

[Kevin Wolf]

The function reads the parents list, so it needs to hold the graph lock.

This happens to result in BlockDriver.bdrv_set_perm() to be called with
the graph lock held. For consistency, make it the same for all of the
BlockDriver callbacks for updating permissions and annotate the function
pointers with GRAPH_RDLOCK_PTR.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-15-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block_int-common.h       |  9 ++++---
 include/block/block_int-global-state.h |  4 +--
 block.c                                | 35 ++++++++++++++++++++------
 blockdev.c                             |  6 +++++
 4 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index fda9d8b5c8..f82c14fb9c 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -413,8 +413,8 @@ struct BlockDriver {
      * If both conditions are met, 0 is returned. Otherwise, -errno is returned
      * and errp is set to an error describing the conflict.
      */
-    int (*bdrv_check_perm)(BlockDriverState *bs, uint64_t perm,
-                           uint64_t shared, Error **errp);
+    int GRAPH_RDLOCK_PTR (*bdrv_check_perm)(BlockDriverState *bs, uint64_t perm,
+                                            uint64_t shared, Error **errp);
 
     /**
      * Called to inform the driver that the set of cumulative set of used
@@ -426,7 +426,8 @@ struct BlockDriver {
      * This function is only invoked after bdrv_check_perm(), so block drivers
      * may rely on preparations made in their .bdrv_check_perm implementation.
      */
-    void (*bdrv_set_perm)(BlockDriverState *bs, uint64_t perm, uint64_t shared);
+    void GRAPH_RDLOCK_PTR (*bdrv_set_perm)(
+        BlockDriverState *bs, uint64_t perm, uint64_t shared);
 
     /*
      * Called to inform the driver that after a previous bdrv_check_perm()
@@ -436,7 +437,7 @@ struct BlockDriver {
      * This function can be called even for nodes that never saw a
      * bdrv_check_perm() call. It is a no-op then.
      */
-    void (*bdrv_abort_perm_update)(BlockDriverState *bs);
+    void GRAPH_RDLOCK_PTR (*bdrv_abort_perm_update)(BlockDriverState *bs);
 
     /**
      * Returns in @nperm and @nshared the permissions that the driver for @bs
diff --git a/include/block/block_int-global-state.h b/include/block/block_int-global-state.h
index bebcc08bce..e2304db58b 100644
--- a/include/block/block_int-global-state.h
+++ b/include/block/block_int-global-state.h
@@ -204,8 +204,8 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
                                   void *opaque, Error **errp);
 void bdrv_root_unref_child(BdrvChild *child);
 
-void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
-                              uint64_t *shared_perm);
+void GRAPH_RDLOCK bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
+                                           uint64_t *shared_perm);
 
 /**
  * Sets a BdrvChild's permissions.  Avoid if the parent is a BDS; use
diff --git a/block.c b/block.c
index 6720bc4f8a..186efda70f 100644
--- a/block.c
+++ b/block.c
@@ -2320,7 +2320,7 @@ static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm,
     tran_add(tran, &bdrv_child_set_pem_drv, s);
 }
 
-static void bdrv_drv_set_perm_commit(void *opaque)
+static void GRAPH_RDLOCK bdrv_drv_set_perm_commit(void *opaque)
 {
     BlockDriverState *bs = opaque;
     uint64_t cumulative_perms, cumulative_shared_perms;
@@ -2333,7 +2333,7 @@ static void bdrv_drv_set_perm_commit(void *opaque)
     }
 }
 
-static void bdrv_drv_set_perm_abort(void *opaque)
+static void GRAPH_RDLOCK bdrv_drv_set_perm_abort(void *opaque)
 {
     BlockDriverState *bs = opaque;
     GLOBAL_STATE_CODE();
@@ -2348,9 +2348,13 @@ TransactionActionDrv bdrv_drv_set_perm_drv = {
     .commit = bdrv_drv_set_perm_commit,
 };
 
-static int bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm,
-                             uint64_t shared_perm, Transaction *tran,
-                             Error **errp)
+/*
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a reader lock for the graph.
+ */
+static int GRAPH_RDLOCK
+bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared_perm,
+                  Transaction *tran, Error **errp)
 {
     GLOBAL_STATE_CODE();
     if (!bs->drv) {
@@ -2457,9 +2461,13 @@ bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
 /*
  * Refresh permissions in @bs subtree. The function is intended to be called
  * after some graph modification that was done without permission update.
+ *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a reader lock for the graph.
  */
-static int bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
-                                  Transaction *tran, Error **errp)
+static int GRAPH_RDLOCK
+bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
+                       Transaction *tran, Error **errp)
 {
     BlockDriver *drv = bs->drv;
     BdrvChild *c;
@@ -2532,6 +2540,9 @@ static int bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
 /*
  * @list is a product of bdrv_topological_dfs() (may be called several times) -
  * a topologically sorted subgraph.
+ *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a reader lock for the graph.
  */
 static int GRAPH_RDLOCK
 bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
@@ -2561,6 +2572,9 @@ bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
  * @list is any list of nodes. List is completed by all subtrees and
  * topologically sorted. It's not a problem if some node occurs in the @list
  * several times.
+ *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a reader lock for the graph.
  */
 static int GRAPH_RDLOCK
 bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
@@ -2623,7 +2637,12 @@ char *bdrv_perm_names(uint64_t perm)
 }
 
 
-/* @tran is allowed to be NULL. In this case no rollback is possible */
+/*
+ * @tran is allowed to be NULL. In this case no rollback is possible.
+ *
+ * After calling this function, the transaction @tran may only be completed
+ * while holding a reader lock for the graph.
+ */
 static int GRAPH_RDLOCK
 bdrv_refresh_perms(BlockDriverState *bs, Transaction *tran, Error **errp)
 {
diff --git a/blockdev.c b/blockdev.c
index e6eba61484..372eaf198c 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1378,6 +1378,9 @@ static void external_snapshot_action(TransactionAction *action,
     AioContext *aio_context;
     uint64_t perm, shared;
 
+    /* TODO We'll eventually have to take a writer lock in this function */
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
+
     tran_add(tran, &external_snapshot_drv, state);
 
     /* 'blockdev-snapshot' and 'blockdev-snapshot-sync' have similar
@@ -2521,6 +2524,9 @@ void qmp_block_commit(const char *job_id, const char *device,
     int job_flags = JOB_DEFAULT;
     uint64_t top_perm, top_shared;
 
+    /* TODO We'll eventually have to take a writer lock in this function */
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
+
     if (!has_speed) {
         speed = 0;
     }
-- 
2.41.0

[PULL 15/28] block: Mark bdrv_child_perm() GRAPH_RDLOCK

[Kevin Wolf]

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_child_perm() need to hold a reader lock for the graph because
some implementations access the children list of a node.

The callers of bdrv_child_perm() conveniently already hold the lock.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-16-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block_int-common.h | 10 +++++-----
 block.c                          | 11 ++++++-----
 block/copy-before-write.c        | 10 +++++-----
 3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index f82c14fb9c..3feb67ec4a 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -451,11 +451,11 @@ struct BlockDriver {
      * permissions, but those that will be needed after applying the
      * @reopen_queue.
      */
-     void (*bdrv_child_perm)(BlockDriverState *bs, BdrvChild *c,
-                             BdrvChildRole role,
-                             BlockReopenQueue *reopen_queue,
-                             uint64_t parent_perm, uint64_t parent_shared,
-                             uint64_t *nperm, uint64_t *nshared);
+     void GRAPH_RDLOCK_PTR (*bdrv_child_perm)(
+        BlockDriverState *bs, BdrvChild *c, BdrvChildRole role,
+        BlockReopenQueue *reopen_queue,
+        uint64_t parent_perm, uint64_t parent_shared,
+        uint64_t *nperm, uint64_t *nshared);
 
     /**
      * Register/unregister a buffer for I/O. For example, when the driver is
diff --git a/block.c b/block.c
index 186efda70f..0f7f78f8de 100644
--- a/block.c
+++ b/block.c
@@ -2228,11 +2228,12 @@ bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp)
     return false;
 }
 
-static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
-                            BdrvChild *c, BdrvChildRole role,
-                            BlockReopenQueue *reopen_queue,
-                            uint64_t parent_perm, uint64_t parent_shared,
-                            uint64_t *nperm, uint64_t *nshared)
+static void GRAPH_RDLOCK
+bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
+                BdrvChild *c, BdrvChildRole role,
+                BlockReopenQueue *reopen_queue,
+                uint64_t parent_perm, uint64_t parent_shared,
+                uint64_t *nperm, uint64_t *nshared)
 {
     assert(bs->drv && bs->drv->bdrv_child_perm);
     GLOBAL_STATE_CODE();
diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index 9a0e2b69d9..aeaff3bb82 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -341,11 +341,11 @@ static void cbw_refresh_filename(BlockDriverState *bs)
             bs->file->bs->filename);
 }
 
-static void cbw_child_perm(BlockDriverState *bs, BdrvChild *c,
-                           BdrvChildRole role,
-                           BlockReopenQueue *reopen_queue,
-                           uint64_t perm, uint64_t shared,
-                           uint64_t *nperm, uint64_t *nshared)
+static void GRAPH_RDLOCK
+cbw_child_perm(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role,
+               BlockReopenQueue *reopen_queue,
+               uint64_t perm, uint64_t shared,
+               uint64_t *nperm, uint64_t *nshared)
 {
     if (!(role & BDRV_CHILD_FILTERED)) {
         /*
-- 
2.41.0

[PULL 16/28] block: Mark bdrv_parent_cb_change_media() GRAPH_RDLOCK

[Kevin Wolf]

The function reads the parents list, so it needs to hold the graph lock.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-17-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/block.c b/block.c
index 0f7f78f8de..06d2a1b256 100644
--- a/block.c
+++ b/block.c
@@ -3371,7 +3371,8 @@ void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
 }
 
 
-static void bdrv_parent_cb_change_media(BlockDriverState *bs, bool load)
+static void GRAPH_RDLOCK
+bdrv_parent_cb_change_media(BlockDriverState *bs, bool load)
 {
     BdrvChild *c;
     GLOBAL_STATE_CODE();
@@ -3969,6 +3970,9 @@ bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
     GLOBAL_STATE_CODE();
     assert(!qemu_in_coroutine());
 
+    /* TODO We'll eventually have to take a writer lock in this function */
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
+
     if (reference) {
         bool options_non_empty = options ? qdict_size(options) : false;
         qobject_unref(options);
-- 
2.41.0

[PULL 17/28] block: Take graph rdlock in bdrv_drop_intermediate()

[Kevin Wolf]

The function reads the parents list, so it needs to hold the graph lock.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-ID: <20230911094620.45040-18-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block.c b/block.c
index 06d2a1b256..e024a6ccec 100644
--- a/block.c
+++ b/block.c
@@ -5938,9 +5938,11 @@ int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
         backing_file_str = base->filename;
     }
 
+    bdrv_graph_rdlock_main_loop();
     QLIST_FOREACH(c, &top->parents, next_parent) {
         updated_children = g_slist_prepend(updated_children, c);
     }
+    bdrv_graph_rdunlock_main_loop();
 
     /*
      * It seems correct to pass detach_subchain=true here, but it triggers
-- 
2.41.0

[PULL 18/28] block: Take graph rdlock in bdrv_change_aio_context()

[Kevin Wolf]

The function reads the parents list, so it needs to hold the graph lock.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-ID: <20230911094620.45040-19-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/block.c b/block.c
index e024a6ccec..8e589bb2e4 100644
--- a/block.c
+++ b/block.c
@@ -7688,17 +7688,21 @@ static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
         return true;
     }
 
+    bdrv_graph_rdlock_main_loop();
     QLIST_FOREACH(c, &bs->parents, next_parent) {
         if (!bdrv_parent_change_aio_context(c, ctx, visited, tran, errp)) {
+            bdrv_graph_rdunlock_main_loop();
             return false;
         }
     }
 
     QLIST_FOREACH(c, &bs->children, next) {
         if (!bdrv_child_change_aio_context(c, ctx, visited, tran, errp)) {
+            bdrv_graph_rdunlock_main_loop();
             return false;
         }
     }
+    bdrv_graph_rdunlock_main_loop();
 
     state = g_new(BdrvStateSetAioContext, 1);
     *state = (BdrvStateSetAioContext) {
-- 
2.41.0

[PULL 19/28] block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

[Kevin Wolf]

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-20-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block_int-global-state.h | 2 +-
 block.c                                | 6 +++---
 block/block-backend.c                  | 3 +++
 blockjob.c                             | 2 ++
 4 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/block/block_int-global-state.h b/include/block/block_int-global-state.h
index e2304db58b..074b677838 100644
--- a/include/block/block_int-global-state.h
+++ b/include/block/block_int-global-state.h
@@ -202,7 +202,7 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
                                   BdrvChildRole child_role,
                                   uint64_t perm, uint64_t shared_perm,
                                   void *opaque, Error **errp);
-void bdrv_root_unref_child(BdrvChild *child);
+void GRAPH_WRLOCK bdrv_root_unref_child(BdrvChild *child);
 
 void GRAPH_RDLOCK bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
                                            uint64_t *shared_perm);
diff --git a/block.c b/block.c
index 8e589bb2e4..9ea8333a28 100644
--- a/block.c
+++ b/block.c
@@ -3268,7 +3268,6 @@ void bdrv_root_unref_child(BdrvChild *child)
     BlockDriverState *child_bs = child->bs;
 
     GLOBAL_STATE_CODE();
-    bdrv_graph_wrlock(NULL);
     bdrv_replace_child_noperm(child, NULL);
     bdrv_child_free(child);
 
@@ -3288,8 +3287,7 @@ void bdrv_root_unref_child(BdrvChild *child)
                                     NULL);
     }
 
-    bdrv_graph_wrunlock();
-    bdrv_unref(child_bs);
+    bdrv_schedule_unref(child_bs);
 }
 
 typedef struct BdrvSetInheritsFrom {
@@ -3366,8 +3364,10 @@ void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
         return;
     }
 
+    bdrv_graph_wrlock(NULL);
     bdrv_unset_inherits_from(parent, child, NULL);
     bdrv_root_unref_child(child);
+    bdrv_graph_wrunlock();
 }
 
 
diff --git a/block/block-backend.c b/block/block-backend.c
index 8d0282a5d9..c2636f4351 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -915,7 +915,10 @@ void blk_remove_bs(BlockBackend *blk)
     blk_drain(blk);
     root = blk->root;
     blk->root = NULL;
+
+    bdrv_graph_wrlock(NULL);
     bdrv_root_unref_child(root);
+    bdrv_graph_wrunlock();
 }
 
 /*
diff --git a/blockjob.c b/blockjob.c
index 25fe8e625d..58c5d64539 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -198,6 +198,7 @@ void block_job_remove_all_bdrv(BlockJob *job)
      * one to make sure that such a concurrent access does not attempt
      * to process an already freed BdrvChild.
      */
+    bdrv_graph_wrlock(NULL);
     while (job->nodes) {
         GSList *l = job->nodes;
         BdrvChild *c = l->data;
@@ -209,6 +210,7 @@ void block_job_remove_all_bdrv(BlockJob *job)
 
         g_slist_free_1(l);
     }
+    bdrv_graph_wrunlock();
 }
 
 bool block_job_has_bdrv(BlockJob *job, BlockDriverState *bs)
-- 
2.41.0

[PULL 20/28] block: Mark bdrv_unref_child() GRAPH_WRLOCK

[Kevin Wolf]

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_unref_child(). These callers will typically
already hold the graph lock once the locking work is completed, which
means that they can't call functions that take it internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-21-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-global-state.h |  7 ++++++-
 block.c                            | 11 +++++++----
 block/blklogwrites.c               |  4 ++++
 block/blkverify.c                  |  2 ++
 block/qcow2.c                      |  4 +++-
 block/quorum.c                     |  6 ++++++
 block/replication.c                |  3 +++
 block/snapshot.c                   |  2 ++
 block/vmdk.c                       | 11 +++++++++++
 tests/unit/test-bdrv-drain.c       |  8 ++++++--
 10 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index eb12a35439..0f6df8f1a2 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -225,7 +225,12 @@ void bdrv_ref(BlockDriverState *bs);
 void no_coroutine_fn bdrv_unref(BlockDriverState *bs);
 void coroutine_fn no_co_wrapper bdrv_co_unref(BlockDriverState *bs);
 void GRAPH_WRLOCK bdrv_schedule_unref(BlockDriverState *bs);
-void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child);
+
+void GRAPH_WRLOCK
+bdrv_unref_child(BlockDriverState *parent, BdrvChild *child);
+
+void coroutine_fn no_co_wrapper_bdrv_wrlock
+bdrv_co_unref_child(BlockDriverState *parent, BdrvChild *child);
 
 BdrvChild * GRAPH_WRLOCK
 bdrv_attach_child(BlockDriverState *parent_bs,
diff --git a/block.c b/block.c
index 9ea8333a28..e7f349b25c 100644
--- a/block.c
+++ b/block.c
@@ -1701,7 +1701,9 @@ bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, const char *node_name,
 open_failed:
     bs->drv = NULL;
     if (bs->file != NULL) {
+        bdrv_graph_wrlock(NULL);
         bdrv_unref_child(bs, bs->file);
+        bdrv_graph_wrunlock();
         assert(!bs->file);
     }
     g_free(bs->opaque);
@@ -3331,8 +3333,9 @@ static void bdrv_set_inherits_from(BlockDriverState *bs,
  * @root that point to @root, where necessary.
  * @tran is allowed to be NULL. In this case no rollback is possible
  */
-static void bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child,
-                                     Transaction *tran)
+static void GRAPH_WRLOCK
+bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child,
+                         Transaction *tran)
 {
     BdrvChild *c;
 
@@ -3364,10 +3367,8 @@ void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
         return;
     }
 
-    bdrv_graph_wrlock(NULL);
     bdrv_unset_inherits_from(parent, child, NULL);
     bdrv_root_unref_child(child);
-    bdrv_graph_wrunlock();
 }
 
 
@@ -5164,9 +5165,11 @@ static void bdrv_close(BlockDriverState *bs)
         bs->drv = NULL;
     }
 
+    bdrv_graph_wrlock(NULL);
     QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
         bdrv_unref_child(bs, child);
     }
+    bdrv_graph_wrunlock();
 
     assert(!bs->backing);
     assert(!bs->file);
diff --git a/block/blklogwrites.c b/block/blklogwrites.c
index 3ea7141cb5..a0d70729bb 100644
--- a/block/blklogwrites.c
+++ b/block/blklogwrites.c
@@ -251,7 +251,9 @@ static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
     ret = 0;
 fail_log:
     if (ret < 0) {
+        bdrv_graph_wrlock(NULL);
         bdrv_unref_child(bs, s->log_file);
+        bdrv_graph_wrunlock();
         s->log_file = NULL;
     }
 fail:
@@ -263,8 +265,10 @@ static void blk_log_writes_close(BlockDriverState *bs)
 {
     BDRVBlkLogWritesState *s = bs->opaque;
 
+    bdrv_graph_wrlock(NULL);
     bdrv_unref_child(bs, s->log_file);
     s->log_file = NULL;
+    bdrv_graph_wrunlock();
 }
 
 static int64_t coroutine_fn GRAPH_RDLOCK
diff --git a/block/blkverify.c b/block/blkverify.c
index 7326461f30..dae9716a26 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -151,8 +151,10 @@ static void blkverify_close(BlockDriverState *bs)
 {
     BDRVBlkverifyState *s = bs->opaque;
 
+    bdrv_graph_wrlock(NULL);
     bdrv_unref_child(bs, s->test_file);
     s->test_file = NULL;
+    bdrv_graph_wrunlock();
 }
 
 static int64_t coroutine_fn GRAPH_RDLOCK
diff --git a/block/qcow2.c b/block/qcow2.c
index b48cd9ce63..071004b302 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1880,7 +1880,7 @@ qcow2_do_open(BlockDriverState *bs, QDict *options, int flags,
     g_free(s->image_data_file);
     if (open_data_file && has_data_file(bs)) {
         bdrv_graph_co_rdunlock();
-        bdrv_unref_child(bs, s->data_file);
+        bdrv_co_unref_child(bs, s->data_file);
         bdrv_graph_co_rdlock();
         s->data_file = NULL;
     }
@@ -2790,7 +2790,9 @@ static void qcow2_do_close(BlockDriverState *bs, bool close_data_file)
     g_free(s->image_backing_format);
 
     if (close_data_file && has_data_file(bs)) {
+        bdrv_graph_wrlock(NULL);
         bdrv_unref_child(bs, s->data_file);
+        bdrv_graph_wrunlock();
         s->data_file = NULL;
     }
 
diff --git a/block/quorum.c b/block/quorum.c
index def0539fda..620a50ba2c 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1037,12 +1037,14 @@ static int quorum_open(BlockDriverState *bs, QDict *options, int flags,
 
 close_exit:
     /* cleanup on error */
+    bdrv_graph_wrlock(NULL);
     for (i = 0; i < s->num_children; i++) {
         if (!opened[i]) {
             continue;
         }
         bdrv_unref_child(bs, s->children[i]);
     }
+    bdrv_graph_wrunlock();
     g_free(s->children);
     g_free(opened);
 exit:
@@ -1055,9 +1057,11 @@ static void quorum_close(BlockDriverState *bs)
     BDRVQuorumState *s = bs->opaque;
     int i;
 
+    bdrv_graph_wrlock(NULL);
     for (i = 0; i < s->num_children; i++) {
         bdrv_unref_child(bs, s->children[i]);
     }
+    bdrv_graph_wrunlock();
 
     g_free(s->children);
 }
@@ -1147,7 +1151,9 @@ static void quorum_del_child(BlockDriverState *bs, BdrvChild *child,
     memmove(&s->children[i], &s->children[i + 1],
             (s->num_children - i - 1) * sizeof(BdrvChild *));
     s->children = g_renew(BdrvChild *, s->children, --s->num_children);
+    bdrv_graph_wrlock(NULL);
     bdrv_unref_child(bs, child);
+    bdrv_graph_wrunlock();
 
     quorum_refresh_flags(bs);
     bdrv_drained_end(bs);
diff --git a/block/replication.c b/block/replication.c
index eec9819625..dd166d2d82 100644
--- a/block/replication.c
+++ b/block/replication.c
@@ -672,10 +672,13 @@ static void replication_done(void *opaque, int ret)
     if (ret == 0) {
         s->stage = BLOCK_REPLICATION_DONE;
 
+        bdrv_graph_wrlock(NULL);
         bdrv_unref_child(bs, s->secondary_disk);
         s->secondary_disk = NULL;
         bdrv_unref_child(bs, s->hidden_disk);
         s->hidden_disk = NULL;
+        bdrv_graph_wrunlock();
+
         s->error = 0;
     } else {
         s->stage = BLOCK_REPLICATION_FAILOVER_FAILED;
diff --git a/block/snapshot.c b/block/snapshot.c
index e22ac3eac6..b86b5b24ad 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -281,7 +281,9 @@ int bdrv_snapshot_goto(BlockDriverState *bs,
         }
 
         /* .bdrv_open() will re-attach it */
+        bdrv_graph_wrlock(NULL);
         bdrv_unref_child(bs, fallback);
+        bdrv_graph_wrunlock();
 
         ret = bdrv_snapshot_goto(fallback_bs, snapshot_id, errp);
         open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err);
diff --git a/block/vmdk.c b/block/vmdk.c
index 84185b73a2..78baa04c0c 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -272,6 +272,7 @@ static void vmdk_free_extents(BlockDriverState *bs)
     BDRVVmdkState *s = bs->opaque;
     VmdkExtent *e;
 
+    bdrv_graph_wrlock(NULL);
     for (i = 0; i < s->num_extents; i++) {
         e = &s->extents[i];
         g_free(e->l1_table);
@@ -282,6 +283,8 @@ static void vmdk_free_extents(BlockDriverState *bs)
             bdrv_unref_child(bs, e->file);
         }
     }
+    bdrv_graph_wrunlock();
+
     g_free(s->extents);
 }
 
@@ -1220,7 +1223,9 @@ static int vmdk_parse_extents(const char *desc, BlockDriverState *bs,
             ret = vmdk_add_extent(bs, extent_file, true, sectors,
                             0, 0, 0, 0, 0, &extent, errp);
             if (ret < 0) {
+                bdrv_graph_wrlock(NULL);
                 bdrv_unref_child(bs, extent_file);
+                bdrv_graph_wrunlock();
                 goto out;
             }
             extent->flat_start_offset = flat_offset << 9;
@@ -1235,20 +1240,26 @@ static int vmdk_parse_extents(const char *desc, BlockDriverState *bs,
             }
             g_free(buf);
             if (ret) {
+                bdrv_graph_wrlock(NULL);
                 bdrv_unref_child(bs, extent_file);
+                bdrv_graph_wrunlock();
                 goto out;
             }
             extent = &s->extents[s->num_extents - 1];
         } else if (!strcmp(type, "SESPARSE")) {
             ret = vmdk_open_se_sparse(bs, extent_file, bs->open_flags, errp);
             if (ret) {
+                bdrv_graph_wrlock(NULL);
                 bdrv_unref_child(bs, extent_file);
+                bdrv_graph_wrunlock();
                 goto out;
             }
             extent = &s->extents[s->num_extents - 1];
         } else {
             error_setg(errp, "Unsupported extent type '%s'", type);
+            bdrv_graph_wrlock(NULL);
             bdrv_unref_child(bs, extent_file);
+            bdrv_graph_wrunlock();
             ret = -ENOTSUP;
             goto out;
         }
diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index 6d33249656..b040a73bb9 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -967,9 +967,12 @@ typedef struct BDRVTestTopState {
 static void bdrv_test_top_close(BlockDriverState *bs)
 {
     BdrvChild *c, *next_c;
+
+    bdrv_graph_wrlock(NULL);
     QLIST_FOREACH_SAFE(c, &bs->children, next, next_c) {
         bdrv_unref_child(bs, c);
     }
+    bdrv_graph_wrunlock();
 }
 
 static int coroutine_fn GRAPH_RDLOCK
@@ -1024,7 +1027,7 @@ static void coroutine_fn test_co_delete_by_drain(void *opaque)
     } else {
         BdrvChild *c, *next_c;
         QLIST_FOREACH_SAFE(c, &bs->children, next, next_c) {
-            bdrv_unref_child(bs, c);
+            bdrv_co_unref_child(bs, c);
         }
     }
 
@@ -1162,10 +1165,11 @@ static void detach_indirect_bh(void *opaque)
     struct detach_by_parent_data *data = opaque;
 
     bdrv_dec_in_flight(data->child_b->bs);
+
+    bdrv_graph_wrlock(NULL);
     bdrv_unref_child(data->parent_b, data->child_b);
 
     bdrv_ref(data->c);
-    bdrv_graph_wrlock(NULL);
     data->child_c = bdrv_attach_child(data->parent_b, data->c, "PB-C",
                                       &child_of_bds, BDRV_CHILD_DATA,
                                       &error_abort);
-- 
2.41.0

[PULL 21/28] block: Mark bdrv_add/del_child() and caller GRAPH_WRLOCK

[Kevin Wolf]

The functions read the parents list in the generic block layer, so we
need to hold the graph lock already there. The BlockDriver
implementations actually modify the graph, so it has to be a writer
lock.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-22-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-global-state.h |  8 +++++---
 include/block/block_int-common.h   |  9 +++++----
 block/quorum.c                     | 23 ++++++-----------------
 blockdev.c                         | 17 +++++++++++------
 4 files changed, 27 insertions(+), 30 deletions(-)

diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index 0f6df8f1a2..f31660c7b1 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -276,9 +276,11 @@ int bdrv_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz);
 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo);
 
-void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
-                    Error **errp);
-void bdrv_del_child(BlockDriverState *parent, BdrvChild *child, Error **errp);
+void GRAPH_WRLOCK
+bdrv_add_child(BlockDriverState *parent, BlockDriverState *child, Error **errp);
+
+void GRAPH_WRLOCK
+bdrv_del_child(BlockDriverState *parent, BdrvChild *child, Error **errp);
 
 /**
  *
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 3feb67ec4a..2ca3758cb8 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -393,10 +393,11 @@ struct BlockDriver {
      */
     int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
 
-    void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child,
-                           Error **errp);
-    void (*bdrv_del_child)(BlockDriverState *parent, BdrvChild *child,
-                           Error **errp);
+    void GRAPH_WRLOCK_PTR (*bdrv_add_child)(
+        BlockDriverState *parent, BlockDriverState *child, Error **errp);
+
+    void GRAPH_WRLOCK_PTR (*bdrv_del_child)(
+        BlockDriverState *parent, BdrvChild *child, Error **errp);
 
     /**
      * Informs the block driver that a permission change is intended. The
diff --git a/block/quorum.c b/block/quorum.c
index 620a50ba2c..05220cab7f 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1066,8 +1066,8 @@ static void quorum_close(BlockDriverState *bs)
     g_free(s->children);
 }
 
-static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs,
-                             Error **errp)
+static void GRAPH_WRLOCK
+quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs, Error **errp)
 {
     BDRVQuorumState *s = bs->opaque;
     BdrvChild *child;
@@ -1093,29 +1093,22 @@ static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs,
     }
     s->next_child_index++;
 
-    bdrv_drained_begin(bs);
-
     /* We can safely add the child now */
     bdrv_ref(child_bs);
 
-    bdrv_graph_wrlock(child_bs);
     child = bdrv_attach_child(bs, child_bs, indexstr, &child_of_bds,
                               BDRV_CHILD_DATA, errp);
-    bdrv_graph_wrunlock();
     if (child == NULL) {
         s->next_child_index--;
-        goto out;
+        return;
     }
     s->children = g_renew(BdrvChild *, s->children, s->num_children + 1);
     s->children[s->num_children++] = child;
     quorum_refresh_flags(bs);
-
-out:
-    bdrv_drained_end(bs);
 }
 
-static void quorum_del_child(BlockDriverState *bs, BdrvChild *child,
-                             Error **errp)
+static void GRAPH_WRLOCK
+quorum_del_child(BlockDriverState *bs, BdrvChild *child, Error **errp)
 {
     BDRVQuorumState *s = bs->opaque;
     char indexstr[INDEXSTR_LEN];
@@ -1145,18 +1138,14 @@ static void quorum_del_child(BlockDriverState *bs, BdrvChild *child,
         s->next_child_index--;
     }
 
-    bdrv_drained_begin(bs);
-
     /* We can safely remove this child now */
     memmove(&s->children[i], &s->children[i + 1],
             (s->num_children - i - 1) * sizeof(BdrvChild *));
     s->children = g_renew(BdrvChild *, s->children, --s->num_children);
-    bdrv_graph_wrlock(NULL);
+
     bdrv_unref_child(bs, child);
-    bdrv_graph_wrunlock();
 
     quorum_refresh_flags(bs);
-    bdrv_drained_end(bs);
 }
 
 static void quorum_gather_child_options(BlockDriverState *bs, QDict *target,
diff --git a/blockdev.c b/blockdev.c
index 372eaf198c..325b7a3bef 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3545,8 +3545,8 @@ out:
     aio_context_release(aio_context);
 }
 
-static BdrvChild *bdrv_find_child(BlockDriverState *parent_bs,
-                                  const char *child_name)
+static BdrvChild * GRAPH_RDLOCK
+bdrv_find_child(BlockDriverState *parent_bs, const char *child_name)
 {
     BdrvChild *child;
 
@@ -3565,9 +3565,11 @@ void qmp_x_blockdev_change(const char *parent, const char *child,
     BlockDriverState *parent_bs, *new_bs = NULL;
     BdrvChild *p_child;
 
+    bdrv_graph_wrlock(NULL);
+
     parent_bs = bdrv_lookup_bs(parent, parent, errp);
     if (!parent_bs) {
-        return;
+        goto out;
     }
 
     if (!child == !node) {
@@ -3576,7 +3578,7 @@ void qmp_x_blockdev_change(const char *parent, const char *child,
         } else {
             error_setg(errp, "Either child or node must be specified");
         }
-        return;
+        goto out;
     }
 
     if (child) {
@@ -3584,7 +3586,7 @@ void qmp_x_blockdev_change(const char *parent, const char *child,
         if (!p_child) {
             error_setg(errp, "Node '%s' does not have child '%s'",
                        parent, child);
-            return;
+            goto out;
         }
         bdrv_del_child(parent_bs, p_child, errp);
     }
@@ -3593,10 +3595,13 @@ void qmp_x_blockdev_change(const char *parent, const char *child,
         new_bs = bdrv_find_node(node);
         if (!new_bs) {
             error_setg(errp, "Node '%s' not found", node);
-            return;
+            goto out;
         }
         bdrv_add_child(parent_bs, new_bs, errp);
     }
+
+out:
+    bdrv_graph_wrunlock();
 }
 
 BlockJobInfoList *qmp_query_block_jobs(Error **errp)
-- 
2.41.0

[PULL 22/28] block: add BDRV_BLOCK_COMPRESSED flag for bdrv_block_status()

[Kevin Wolf]

From: Andrey Drobyshev via <qemu-block@nongnu.org>

Functions qcow2_get_host_offset(), get_cluster_offset(),
vmdk_co_block_status() explicitly report compressed cluster types when data
is compressed.  However, this information is never passed further.  Let's
make use of it by adding new BDRV_BLOCK_COMPRESSED flag for
bdrv_block_status(), so that caller may know that the data range is
compressed.  In particular, we're going to use this flag to tweak
"qemu-img map" output.

This new flag is only being utilized by qcow, qcow2 and vmdk formats, as only
those support compression.

Reviewed-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Message-ID: <20230907210226.953821-2-andrey.drobyshev@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block-common.h | 3 +++
 block/qcow.c                 | 5 ++++-
 block/qcow2.c                | 3 +++
 block/vmdk.c                 | 2 ++
 4 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/include/block/block-common.h b/include/block/block-common.h
index 3bbc5d9294..2d2af7230d 100644
--- a/include/block/block-common.h
+++ b/include/block/block-common.h
@@ -291,6 +291,8 @@ typedef enum {
  *                       layer rather than any backing, set by block layer
  * BDRV_BLOCK_EOF: the returned pnum covers through end of file for this
  *                 layer, set by block layer
+ * BDRV_BLOCK_COMPRESSED: the underlying data is compressed; only valid for
+ *                        the formats supporting compression: qcow, qcow2
  *
  * Internal flags:
  * BDRV_BLOCK_RAW: for use by passthrough drivers, such as raw, to request
@@ -326,6 +328,7 @@ typedef enum {
 #define BDRV_BLOCK_ALLOCATED    0x10
 #define BDRV_BLOCK_EOF          0x20
 #define BDRV_BLOCK_RECURSE      0x40
+#define BDRV_BLOCK_COMPRESSED   0x80
 
 typedef QTAILQ_HEAD(BlockReopenQueue, BlockReopenQueueEntry) BlockReopenQueue;
 
diff --git a/block/qcow.c b/block/qcow.c
index 577bd70324..d56d24ab6d 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -549,7 +549,10 @@ qcow_co_block_status(BlockDriverState *bs, bool want_zero,
     if (!cluster_offset) {
         return 0;
     }
-    if ((cluster_offset & QCOW_OFLAG_COMPRESSED) || s->crypto) {
+    if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
+        return BDRV_BLOCK_DATA | BDRV_BLOCK_COMPRESSED;
+    }
+    if (s->crypto) {
         return BDRV_BLOCK_DATA;
     }
     *map = cluster_offset | index_in_cluster;
diff --git a/block/qcow2.c b/block/qcow2.c
index 071004b302..af43d59d76 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2162,6 +2162,9 @@ qcow2_co_block_status(BlockDriverState *bs, bool want_zero, int64_t offset,
     {
         status |= BDRV_BLOCK_RECURSE;
     }
+    if (type == QCOW2_SUBCLUSTER_COMPRESSED) {
+        status |= BDRV_BLOCK_COMPRESSED;
+    }
     return status;
 }
 
diff --git a/block/vmdk.c b/block/vmdk.c
index 78baa04c0c..e90649c8bf 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1783,6 +1783,8 @@ vmdk_co_block_status(BlockDriverState *bs, bool want_zero,
             if (extent->flat) {
                 ret |= BDRV_BLOCK_RECURSE;
             }
+        } else {
+            ret |= BDRV_BLOCK_COMPRESSED;
         }
         *file = extent->file->bs;
         break;
-- 
2.41.0

[PULL 23/28] qemu-img: map: report compressed data blocks

[Kevin Wolf]

From: Andrey Drobyshev via <qemu-block@nongnu.org>

Right now "qemu-img map" reports compressed blocks as containing data
but having no host offset.  This is not very informative.  Instead,
let's add another boolean field named "compressed" in case JSON output
mode is specified.  This is achieved by utilizing new allocation status
flag BDRV_BLOCK_COMPRESSED for bdrv_block_status().

Also update the expected qemu-iotests outputs to contain the new field.

Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Message-ID: <20230907210226.953821-3-andrey.drobyshev@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 qapi/block-core.json                          |   6 +-
 qemu-img.c                                    |   8 +-
 tests/qemu-iotests/122.out                    |  84 +-
 tests/qemu-iotests/146.out                    | 780 +++++++++---------
 tests/qemu-iotests/154.out                    | 194 ++---
 tests/qemu-iotests/179.out                    | 178 ++--
 tests/qemu-iotests/209.out                    |   4 +-
 tests/qemu-iotests/221.out                    |  16 +-
 tests/qemu-iotests/223.out                    |  60 +-
 tests/qemu-iotests/241.out                    |  10 +-
 tests/qemu-iotests/244.out                    |  24 +-
 tests/qemu-iotests/252.out                    |  10 +-
 tests/qemu-iotests/253.out                    |  20 +-
 tests/qemu-iotests/274.out                    |  48 +-
 .../tests/nbd-qemu-allocation.out             |  16 +-
 tests/qemu-iotests/tests/qemu-img-bitmaps.out |  24 +-
 16 files changed, 744 insertions(+), 738 deletions(-)

diff --git a/qapi/block-core.json b/qapi/block-core.json
index 2b1d493d6e..89751d81f2 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -409,6 +409,8 @@
 #
 # @zero: whether the virtual blocks read as zeroes
 #
+# @compressed: true if the data is stored compressed (since 8.2)
+#
 # @depth: number of layers (0 = top image, 1 = top image's backing
 #     file, ..., n - 1 = bottom image (where n is the number of images
 #     in the chain)) before reaching one for which the range is
@@ -426,8 +428,8 @@
 ##
 { 'struct': 'MapEntry',
   'data': {'start': 'int', 'length': 'int', 'data': 'bool',
-           'zero': 'bool', 'depth': 'int', 'present': 'bool',
-           '*offset': 'int', '*filename': 'str' } }
+           'zero': 'bool', 'compressed': 'bool', 'depth': 'int',
+           'present': 'bool', '*offset': 'int', '*filename': 'str' } }
 
 ##
 # @BlockdevCacheInfo:
diff --git a/qemu-img.c b/qemu-img.c
index 0756dbb835..a48edb7101 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -3108,10 +3108,12 @@ static int dump_map_entry(OutputFormat output_format, MapEntry *e,
     case OFORMAT_JSON:
         printf("{ \"start\": %"PRId64", \"length\": %"PRId64","
                " \"depth\": %"PRId64", \"present\": %s, \"zero\": %s,"
-               " \"data\": %s", e->start, e->length, e->depth,
+               " \"data\": %s, \"compressed\": %s",
+               e->start, e->length, e->depth,
                e->present ? "true" : "false",
                e->zero ? "true" : "false",
-               e->data ? "true" : "false");
+               e->data ? "true" : "false",
+               e->compressed ? "true" : "false");
         if (e->has_offset) {
             printf(", \"offset\": %"PRId64"", e->offset);
         }
@@ -3172,6 +3174,7 @@ static int get_block_status(BlockDriverState *bs, int64_t offset,
         .length = bytes,
         .data = !!(ret & BDRV_BLOCK_DATA),
         .zero = !!(ret & BDRV_BLOCK_ZERO),
+        .compressed = !!(ret & BDRV_BLOCK_COMPRESSED),
         .offset = map,
         .has_offset = has_offset,
         .depth = depth,
@@ -3189,6 +3192,7 @@ static inline bool entry_mergeable(const MapEntry *curr, const MapEntry *next)
     }
     if (curr->zero != next->zero ||
         curr->data != next->data ||
+        curr->compressed != next->compressed ||
         curr->depth != next->depth ||
         curr->present != next->present ||
         !curr->filename != !next->filename ||
diff --git a/tests/qemu-iotests/122.out b/tests/qemu-iotests/122.out
index e18766e167..6a1aa3fe2b 100644
--- a/tests/qemu-iotests/122.out
+++ b/tests/qemu-iotests/122.out
@@ -67,12 +67,12 @@ read 65536/65536 bytes at offset 4194304
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 65536/65536 bytes at offset 8388608
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 65536, "length": 4128768, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 4194304, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 4259840, "length": 4128768, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 8388608, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 8454144, "length": 4128768, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 65536, "length": 4128768, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 4194304, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 4259840, "length": 4128768, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 8388608, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 8454144, "length": 4128768, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 65536/65536 bytes at offset 4194304
@@ -94,12 +94,12 @@ wrote 1024/1024 bytes at offset 1046528
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 wrote 1024/1024 bytes at offset 0
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 65536, "length": 65536, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 131072, "length": 196608, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 327680, "length": 655360, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 983040, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 1048576, "length": 1046528, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 65536, "length": 65536, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 131072, "length": 196608, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 327680, "length": 655360, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 983040, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 1048576, "length": 1046528, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 read 16384/16384 bytes at offset 0
 16 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 16384/16384 bytes at offset 16384
@@ -130,14 +130,14 @@ read 3145728/3145728 bytes at offset 0
 3 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 63963136/63963136 bytes at offset 3145728
 61 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 
 convert -c -S 0:
 read 3145728/3145728 bytes at offset 0
 3 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 63963136/63963136 bytes at offset 3145728
 61 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true}]
+[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true}]
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
 wrote 33554432/33554432 bytes at offset 0
 32 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
@@ -152,7 +152,7 @@ read 30408704/30408704 bytes at offset 3145728
 29 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 33554432/33554432 bytes at offset 33554432
 32 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 
 convert -c -S 0 with source backing file:
 read 3145728/3145728 bytes at offset 0
@@ -161,7 +161,7 @@ read 30408704/30408704 bytes at offset 3145728
 29 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 33554432/33554432 bytes at offset 33554432
 32 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true}]
+[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true}]
 
 convert -S 0 -B ...
 read 3145728/3145728 bytes at offset 0
@@ -170,7 +170,7 @@ read 30408704/30408704 bytes at offset 3145728
 29 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 33554432/33554432 bytes at offset 33554432
 32 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 
 convert -c -S 0 -B ...
 read 3145728/3145728 bytes at offset 0
@@ -179,7 +179,7 @@ read 30408704/30408704 bytes at offset 3145728
 29 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 33554432/33554432 bytes at offset 33554432
 32 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true}]
+[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true}]
 
 === Non-zero -S ===
 
@@ -196,32 +196,32 @@ wrote 1024/1024 bytes at offset 66560
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
 convert -S 4k
-[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 4096, "length": 4096, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 8192, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 12288, "length": 4096, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 16384, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 20480, "length": 67088384, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 4096, "length": 4096, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 8192, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 12288, "length": 4096, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 16384, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 20480, "length": 67088384, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 
 convert -c -S 4k
-[{ "start": 0, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 1024, "length": 7168, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 8192, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 9216, "length": 8192, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 17408, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 18432, "length": 67090432, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 1024, "length": 7168, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 8192, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 9216, "length": 8192, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 17408, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 18432, "length": 67090432, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 
 convert -S 8k
-[{ "start": 0, "length": 24576, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 24576, "length": 67084288, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 24576, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 24576, "length": 67084288, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 
 convert -c -S 8k
-[{ "start": 0, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 1024, "length": 7168, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 8192, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 9216, "length": 8192, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 17408, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true},
-{ "start": 18432, "length": 67090432, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 1024, "length": 7168, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 8192, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 9216, "length": 8192, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 17408, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "compressed": true},
+{ "start": 18432, "length": 67090432, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 
 === -n to a non-zero image ===
 
@@ -235,18 +235,18 @@ Images are identical.
 
 Formatting 'TEST_DIR/t.IMGFMT.orig', fmt=IMGFMT size=67108864
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-[{ "start": 0, "length": 67108864, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 67108864, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 
 === -n to an empty image with a backing file ===
 
 Formatting 'TEST_DIR/t.IMGFMT.orig', fmt=IMGFMT size=67108864
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
-[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
-[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true, "offset": 327680}]
+[{ "start": 0, "length": 67108864, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 327680}]
 
 === -n -B to an image without a backing file ===
 
diff --git a/tests/qemu-iotests/146.out b/tests/qemu-iotests/146.out
index dfd6c77140..a48804154e 100644
--- a/tests/qemu-iotests/146.out
+++ b/tests/qemu-iotests/146.out
@@ -2,414 +2,414 @@ QA output created by 146
 
 === Testing VPC Autodetect ===
 
-[{ "start": 0, "length": 136363130880, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 136363130880, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === Testing VPC with current_size force ===
 
-[{ "start": 0, "length": 136365211648, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 136365211648, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === Testing VPC with chs force ===
 
-[{ "start": 0, "length": 136363130880, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 136363130880, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === Testing Hyper-V Autodetect ===
 
-[{ "start": 0, "length": 136365211648, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 136365211648, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === Testing Hyper-V with current_size force ===
 
-[{ "start": 0, "length": 136365211648, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 136365211648, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === Testing Hyper-V with chs force ===
 
-[{ "start": 0, "length": 136363130880, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 136363130880, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === Testing d2v Autodetect ===
 
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+{ "start": 96468992, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 98566144, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 100663296, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 102760448, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 104857600, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 106954752, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 109051904, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 111149056, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 113246208, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 115343360, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
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+{ "start": 121634816, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
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+{ "start": 125829120, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 127926272, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 130023424, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 132120576, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
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+{ "start": 138412032, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 140509184, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 142606336, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 144703488, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
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+{ "start": 220200960, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
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+{ "start": 224395264, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 226492416, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 228589568, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 230686720, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 232783872, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 234881024, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 236978176, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 239075328, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 241172480, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 243269632, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 245366784, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 247463936, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 249561088, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 251658240, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 253755392, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 255852544, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 257949696, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 260046848, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 262144000, "length": 1310720, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 
 === Testing d2v with current_size force ===
 
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-{ "start": 4194304, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 6291456, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 8388608, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 10485760, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 12582912, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 14680064, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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-{ "start": 18874368, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 20971520, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 23068672, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 25165824, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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-{ "start": 29360128, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 31457280, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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-{ "start": 35651584, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 37748736, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 39845888, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 41943040, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 44040192, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 46137344, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 48234496, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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-{ "start": 52428800, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 54525952, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 56623104, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 58720256, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 60817408, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 62914560, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 65011712, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 67108864, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 69206016, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 71303168, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 73400320, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 75497472, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 77594624, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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-{ "start": 98566144, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 100663296, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 102760448, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 104857600, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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-{ "start": 161480704, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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-{ "start": 180355072, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 182452224, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 184549376, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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+{ "start": 253755392, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
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+{ "start": 260046848, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 262144000, "length": 1310720, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 
 === Testing d2v with chs force ===
 
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+{ "start": 111149056, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 113246208, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 115343360, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 117440512, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 119537664, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 121634816, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 123731968, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 125829120, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 127926272, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 130023424, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 132120576, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 134217728, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 136314880, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 138412032, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 140509184, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 142606336, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 144703488, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 146800640, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 148897792, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 150994944, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 153092096, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 155189248, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 157286400, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 159383552, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 161480704, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 163577856, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 165675008, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 167772160, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 169869312, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 171966464, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 174063616, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 176160768, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 178257920, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 180355072, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 182452224, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 184549376, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 186646528, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 188743680, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 190840832, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 192937984, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 195035136, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 197132288, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 199229440, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 201326592, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 203423744, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 205520896, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 207618048, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 209715200, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 211812352, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 213909504, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 216006656, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 218103808, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 220200960, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 222298112, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 224395264, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 226492416, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 228589568, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 230686720, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 232783872, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 234881024, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 236978176, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 239075328, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 241172480, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 243269632, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 245366784, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 247463936, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 249561088, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 251658240, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 253755392, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 255852544, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 257949696, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 260046848, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 262144000, "length": 1310720, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 
 === Testing Image create, default ===
 
@@ -417,15 +417,15 @@ Formatting 'TEST_DIR/IMGFMT-create-test.IMGFMT', fmt=IMGFMT size=4294967296
 
 === Read created image, default opts ====
 
-[{ "start": 0, "length": 4295467008, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 4295467008, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === Read created image, force_size_calc=chs ====
 
-[{ "start": 0, "length": 4295467008, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 4295467008, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === Read created image, force_size_calc=current_size ====
 
-[{ "start": 0, "length": 4295467008, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 4295467008, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === Testing Image create, force_size ===
 
@@ -433,13 +433,13 @@ Formatting 'TEST_DIR/IMGFMT-create-test.IMGFMT', fmt=IMGFMT size=4294967296
 
 === Read created image, default opts ====
 
-[{ "start": 0, "length": 4294967296, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 4294967296, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === Read created image, force_size_calc=chs ====
 
-[{ "start": 0, "length": 4294967296, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 4294967296, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === Read created image, force_size_calc=current_size ====
 
-[{ "start": 0, "length": 4294967296, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 4294967296, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 *** done
diff --git a/tests/qemu-iotests/154.out b/tests/qemu-iotests/154.out
index 1fa7ffc475..0199269add 100644
--- a/tests/qemu-iotests/154.out
+++ b/tests/qemu-iotests/154.out
@@ -11,14 +11,14 @@ wrote 2048/2048 bytes at offset 17408
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 wrote 2048/2048 bytes at offset 27648
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 4096, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 8192, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 12288, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 16384, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 20480, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 24576, "length": 8192, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 32768, "length": 134184960, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 4096, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 8192, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 12288, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 16384, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 20480, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 24576, "length": 8192, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 32768, "length": 134184960, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 
 == backing file contains non-zero data before write_zeroes ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
@@ -41,11 +41,11 @@ read 1024/1024 bytes at offset 65536
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 2048/2048 bytes at offset 67584
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 32768, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 32768, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 36864, "length": 28672, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 65536, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 69632, "length": 134148096, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 32768, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 32768, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 36864, "length": 28672, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 65536, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 69632, "length": 134148096, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 
 == backing file contains non-zero data after write_zeroes ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
@@ -68,11 +68,11 @@ read 1024/1024 bytes at offset 44032
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 3072/3072 bytes at offset 40960
 3 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 32768, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 32768, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 36864, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 40960, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 45056, "length": 134172672, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 32768, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 32768, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 36864, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 40960, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 45056, "length": 134172672, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 
 == write_zeroes covers non-zero data ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
@@ -101,15 +101,15 @@ wrote 2048/2048 bytes at offset 29696
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 4096/4096 bytes at offset 28672
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 4096, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 8192, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 12288, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 16384, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 20480, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 24576, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 28672, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 32768, "length": 134184960, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 4096, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 8192, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 12288, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 16384, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 20480, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 24576, "length": 4096, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 28672, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 32768, "length": 134184960, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 
 == spanning two clusters, non-zero before request ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
@@ -142,16 +142,16 @@ read 1024/1024 bytes at offset 67584
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 5120/5120 bytes at offset 68608
 5 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 32768, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 32768, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 36864, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 40960, "length": 8192, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 49152, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 53248, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 57344, "length": 8192, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 65536, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 69632, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 73728, "length": 134144000, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 32768, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 32768, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 36864, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 40960, "length": 8192, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 49152, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 53248, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 57344, "length": 8192, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 65536, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 69632, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 73728, "length": 134144000, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 
 == spanning two clusters, non-zero after request ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
@@ -184,16 +184,16 @@ read 7168/7168 bytes at offset 65536
 7 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 1024/1024 bytes at offset 72704
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 32768, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 32768, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 36864, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 40960, "length": 8192, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 49152, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 53248, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 57344, "length": 8192, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 65536, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 69632, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 73728, "length": 134144000, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 32768, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 32768, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 36864, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 40960, "length": 8192, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 49152, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 53248, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 57344, "length": 8192, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 65536, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 69632, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 73728, "length": 134144000, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 
 == spanning two clusters, partially overwriting backing file ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
@@ -212,8 +212,8 @@ read 1024/1024 bytes at offset 5120
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 2048/2048 bytes at offset 6144
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 8192, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 8192, "length": 134209536, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 8192, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 8192, "length": 134209536, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 
 == spanning multiple clusters, non-zero in first cluster ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
@@ -226,10 +226,10 @@ read 2048/2048 bytes at offset 65536
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 10240/10240 bytes at offset 67584
 10 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 65536, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 65536, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 69632, "length": 8192, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 77824, "length": 134139904, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 65536, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 65536, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 69632, "length": 8192, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 77824, "length": 134139904, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 
 == spanning multiple clusters, non-zero in intermediate cluster ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
@@ -240,9 +240,9 @@ wrote 7168/7168 bytes at offset 67584
 7 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 12288/12288 bytes at offset 65536
 12 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 65536, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 65536, "length": 12288, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 77824, "length": 134139904, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 65536, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 65536, "length": 12288, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 77824, "length": 134139904, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 
 == spanning multiple clusters, non-zero in final cluster ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
@@ -255,10 +255,10 @@ read 10240/10240 bytes at offset 65536
 10 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 2048/2048 bytes at offset 75776
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 65536, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 65536, "length": 8192, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 73728, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 77824, "length": 134139904, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 65536, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 65536, "length": 8192, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 73728, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 77824, "length": 134139904, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 
 == spanning multiple clusters, partially overwriting backing file ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
@@ -277,88 +277,88 @@ read 2048/2048 bytes at offset 74752
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 1024/1024 bytes at offset 76800
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 65536, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 65536, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 69632, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 73728, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 77824, "length": 134139904, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 65536, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 65536, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 69632, "length": 4096, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 73728, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 77824, "length": 134139904, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 
 == unaligned image tail cluster, no allocation needed ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776
 wrote 512/512 bytes at offset 134217728
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776
 wrote 512/512 bytes at offset 134219264
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776
 wrote 1024/1024 bytes at offset 134218240
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776
 wrote 2048/2048 bytes at offset 134217728
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134218752
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
 wrote 512/512 bytes at offset 134217728
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
 wrote 512/512 bytes at offset 134219264
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
 wrote 1024/1024 bytes at offset 134218240
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
 wrote 2048/2048 bytes at offset 134217728
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 wrote 512/512 bytes at offset 134217728
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
 wrote 512/512 bytes at offset 134217728
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
 wrote 512/512 bytes at offset 134219264
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
 wrote 1024/1024 bytes at offset 134218240
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
 wrote 2048/2048 bytes at offset 134217728
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 2048/2048 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134218752
 wrote 1024/1024 bytes at offset 134217728
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
@@ -369,15 +369,15 @@ read 512/512 bytes at offset 134217728
 read 512/512 bytes at offset 134218240
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 1024/1024 bytes allocated at offset 128 MiB
-[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 wrote 1024/1024 bytes at offset 134217728
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 1024/1024 bytes allocated at offset 128 MiB
 read 1024/1024 bytes at offset 134217728
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 1024, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET}]
+[{ "start": 0, "length": 134217728, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 1024, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET}]
 
 == unaligned image tail cluster, allocation required ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134218752
@@ -390,8 +390,8 @@ read 512/512 bytes at offset 134217728
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 1536/1536 bytes at offset 134218240
 1.500 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134218752
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
 wrote 512/512 bytes at offset 134218240
@@ -412,6 +412,6 @@ read 512/512 bytes at offset 134218240
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 1024/1024 bytes at offset 134218752
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 134217728, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 *** done
diff --git a/tests/qemu-iotests/179.out b/tests/qemu-iotests/179.out
index 7cf22cd75f..65b909ebc2 100644
--- a/tests/qemu-iotests/179.out
+++ b/tests/qemu-iotests/179.out
@@ -13,11 +13,11 @@ wrote 2097152/2097152 bytes at offset 6291456
 2 MiB (0x200000) bytes not allocated at offset 4 MiB (0x400000)
 2 MiB (0x200000) bytes     allocated at offset 6 MiB (0x600000)
 56 MiB (0x3800000) bytes not allocated at offset 8 MiB (0x800000)
-[{ "start": 0, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 4194304, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 6291456, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 8388608, "length": 58720256, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 4194304, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 6291456, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 8388608, "length": 58720256, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 wrote 2097150/2097150 bytes at offset 10485761
 2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 wrote 2097150/2097150 bytes at offset 14680065
@@ -31,15 +31,15 @@ wrote 2097150/2097150 bytes at offset 14680065
 2 MiB (0x200000) bytes not allocated at offset 12 MiB (0xc00000)
 2 MiB (0x200000) bytes     allocated at offset 14 MiB (0xe00000)
 48 MiB (0x3000000) bytes not allocated at offset 16 MiB (0x1000000)
-[{ "start": 0, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 4194304, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 6291456, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 8388608, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 10485760, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 12582912, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 14680064, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 16777216, "length": 50331648, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 4194304, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 6291456, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 8388608, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 10485760, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 12582912, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 14680064, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 16777216, "length": 50331648, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 wrote 14680064/14680064 bytes at offset 18874368
 14 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 wrote 2097152/2097152 bytes at offset 20971520
@@ -57,21 +57,21 @@ wrote 6291456/6291456 bytes at offset 25165824
 2 MiB (0x200000) bytes not allocated at offset 16 MiB (0x1000000)
 14 MiB (0xe00000) bytes     allocated at offset 18 MiB (0x1200000)
 32 MiB (0x2000000) bytes not allocated at offset 32 MiB (0x2000000)
-[{ "start": 0, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 4194304, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 6291456, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 8388608, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 10485760, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 12582912, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 14680064, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 16777216, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 18874368, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 20971520, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 23068672, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 25165824, "length": 6291456, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 31457280, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 33554432, "length": 33554432, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 4194304, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 6291456, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 8388608, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 10485760, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 12582912, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 14680064, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 16777216, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 18874368, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 20971520, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 23068672, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 25165824, "length": 6291456, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 31457280, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 33554432, "length": 33554432, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 wrote 2097152/2097152 bytes at offset 27262976
 2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 wrote 2097152/2097152 bytes at offset 29360128
@@ -87,23 +87,23 @@ wrote 2097152/2097152 bytes at offset 29360128
 2 MiB (0x200000) bytes not allocated at offset 16 MiB (0x1000000)
 14 MiB (0xe00000) bytes     allocated at offset 18 MiB (0x1200000)
 32 MiB (0x2000000) bytes not allocated at offset 32 MiB (0x2000000)
-[{ "start": 0, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 4194304, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 6291456, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 8388608, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 10485760, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 12582912, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 14680064, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 16777216, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 18874368, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 20971520, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 23068672, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 25165824, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 27262976, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 29360128, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 31457280, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 33554432, "length": 33554432, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 4194304, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 6291456, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 8388608, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 10485760, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 12582912, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 14680064, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 16777216, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 18874368, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 20971520, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 23068672, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 25165824, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 27262976, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 29360128, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 31457280, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 33554432, "length": 33554432, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 wrote 8388608/8388608 bytes at offset 33554432
 8 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 wrote 2097152/2097152 bytes at offset 35651584
@@ -121,24 +121,24 @@ wrote 2097152/2097152 bytes at offset 37748736
 2 MiB (0x200000) bytes not allocated at offset 16 MiB (0x1000000)
 22 MiB (0x1600000) bytes     allocated at offset 18 MiB (0x1200000)
 24 MiB (0x1800000) bytes not allocated at offset 40 MiB (0x2800000)
-[{ "start": 0, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 4194304, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 6291456, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 8388608, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 10485760, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 12582912, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 14680064, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 16777216, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 18874368, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 20971520, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 23068672, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 25165824, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 27262976, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 29360128, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 31457280, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 33554432, "length": 8388608, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 41943040, "length": 25165824, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 4194304, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 6291456, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 8388608, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 10485760, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 12582912, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 14680064, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 16777216, "length": 2097152, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 18874368, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 20971520, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 23068672, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 25165824, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 27262976, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 29360128, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 31457280, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 33554432, "length": 8388608, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 41943040, "length": 25165824, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 wrote 8388608/8388608 bytes at offset 41943040
 8 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 wrote 8388608/8388608 bytes at offset 50331648
@@ -162,31 +162,31 @@ wrote 2097152/2097152 bytes at offset 62914560
 4 MiB (0x400000) bytes not allocated at offset 54 MiB (0x3600000)
 4 MiB (0x400000) bytes     allocated at offset 58 MiB (0x3a00000)
 2 MiB (0x200000) bytes not allocated at offset 62 MiB (0x3e00000)
-[{ "start": 0, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 2097152, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false},
-{ "start": 4194304, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 6291456, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false},
-{ "start": 8388608, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 10485760, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false},
-{ "start": 12582912, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 14680064, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false},
-{ "start": 16777216, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 18874368, "length": 2097152, "depth": 1, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 20971520, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false},
-{ "start": 23068672, "length": 2097152, "depth": 1, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 25165824, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 27262976, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false},
-{ "start": 29360128, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 31457280, "length": 2097152, "depth": 1, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 33554432, "length": 10485760, "depth": 1, "present": true, "zero": true, "data": false},
-{ "start": 44040192, "length": 4194304, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 48234496, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false},
-{ "start": 50331648, "length": 2097152, "depth": 1, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 52428800, "length": 4194304, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 56623104, "length": 2097152, "depth": 1, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 58720256, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 60817408, "length": 4194304, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 65011712, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 2097152, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 4194304, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 6291456, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 8388608, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 10485760, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 12582912, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 14680064, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 16777216, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 18874368, "length": 2097152, "depth": 1, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 20971520, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 23068672, "length": 2097152, "depth": 1, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 25165824, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 27262976, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 29360128, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 31457280, "length": 2097152, "depth": 1, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 33554432, "length": 10485760, "depth": 1, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 44040192, "length": 4194304, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 48234496, "length": 2097152, "depth": 1, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 50331648, "length": 2097152, "depth": 1, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 52428800, "length": 4194304, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 56623104, "length": 2097152, "depth": 1, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 58720256, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 60817408, "length": 4194304, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 65011712, "length": 2097152, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 No errors were found on the image.
 No errors were found on the image.
 
diff --git a/tests/qemu-iotests/209.out b/tests/qemu-iotests/209.out
index 515906ac7a..79c4103a22 100644
--- a/tests/qemu-iotests/209.out
+++ b/tests/qemu-iotests/209.out
@@ -1,4 +1,4 @@
-[{ "start": 0, "length": 524288, "depth": 0, "present": true, "zero": false, "data": true, "offset": 0},
-{ "start": 524288, "length": 524288, "depth": 0, "present": true, "zero": true, "data": false, "offset": 524288}]
+[{ "start": 0, "length": 524288, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 0},
+{ "start": 524288, "length": 524288, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": 524288}]
 
 done.
diff --git a/tests/qemu-iotests/221.out b/tests/qemu-iotests/221.out
index 9cdd171a2d..df231c4e3d 100644
--- a/tests/qemu-iotests/221.out
+++ b/tests/qemu-iotests/221.out
@@ -5,14 +5,14 @@ QA output created by 221
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=65537
 discard 65537/65537 bytes at offset 0
 64.001 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 66048, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET}]
-[{ "start": 0, "length": 66048, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET}]
+[{ "start": 0, "length": 66048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET}]
+[{ "start": 0, "length": 66048, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET}]
 wrote 1/1 bytes at offset 65536
 1 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 65536, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 65536, "length": 1, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 65537, "length": 511, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET}]
-[{ "start": 0, "length": 65536, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 65536, "length": 1, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 65537, "length": 511, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET}]
+[{ "start": 0, "length": 65536, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 65536, "length": 1, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 65537, "length": 511, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET}]
+[{ "start": 0, "length": 65536, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 65536, "length": 1, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 65537, "length": 511, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET}]
 *** done
diff --git a/tests/qemu-iotests/223.out b/tests/qemu-iotests/223.out
index 26fb347c5d..86a37014d0 100644
--- a/tests/qemu-iotests/223.out
+++ b/tests/qemu-iotests/223.out
@@ -120,23 +120,23 @@ read 1048576/1048576 bytes at offset 1048576
 1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 2097152/2097152 bytes at offset 2097152
 2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 4096, "length": 1044480, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 1048576, "length": 3145728, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
-[{ "start": 0, "length": 65536, "depth": 0, "present": false, "zero": false, "data": false},
-{ "start": 65536, "length": 2031616, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
+[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 4096, "length": 1044480, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 1048576, "length": 3145728, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
+[{ "start": 0, "length": 65536, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false},
+{ "start": 65536, "length": 2031616, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false}]
 
 === Contrast to small granularity dirty-bitmap ===
 
-[{ "start": 0, "length": 512, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 512, "length": 512, "depth": 0, "present": false, "zero": false, "data": false},
-{ "start": 1024, "length": 2096128, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
+[{ "start": 0, "length": 512, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 512, "length": 512, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false},
+{ "start": 1024, "length": 2096128, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false}]
 
 === Check bitmap taken from another node ===
 
-[{ "start": 0, "length": 4194304, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 4194304, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 
 === End qemu NBD server ===
 
@@ -239,23 +239,23 @@ read 1048576/1048576 bytes at offset 1048576
 1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 2097152/2097152 bytes at offset 2097152
 2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 4096, "length": 1044480, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 1048576, "length": 3145728, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
-[{ "start": 0, "length": 65536, "depth": 0, "present": false, "zero": false, "data": false},
-{ "start": 65536, "length": 2031616, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
+[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 4096, "length": 1044480, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 1048576, "length": 3145728, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
+[{ "start": 0, "length": 65536, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false},
+{ "start": 65536, "length": 2031616, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false}]
 
 === Contrast to small granularity dirty-bitmap ===
 
-[{ "start": 0, "length": 512, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 512, "length": 512, "depth": 0, "present": false, "zero": false, "data": false},
-{ "start": 1024, "length": 2096128, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
+[{ "start": 0, "length": 512, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 512, "length": 512, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false},
+{ "start": 1024, "length": 2096128, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false}]
 
 === Check bitmap taken from another node ===
 
-[{ "start": 0, "length": 4194304, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 4194304, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 
 === End qemu NBD server ===
 
@@ -281,12 +281,12 @@ read 2097152/2097152 bytes at offset 2097152
 
 === Use qemu-nbd as server ===
 
-[{ "start": 0, "length": 65536, "depth": 0, "present": false, "zero": false, "data": false},
-{ "start": 65536, "length": 2031616, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
-[{ "start": 0, "length": 512, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 512, "length": 512, "depth": 0, "present": false, "zero": false, "data": false},
-{ "start": 1024, "length": 11321, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
-[{ "start": 12345, "length": 2084807, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
+[{ "start": 0, "length": 65536, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false},
+{ "start": 65536, "length": 2031616, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false}]
+[{ "start": 0, "length": 512, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 512, "length": 512, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false},
+{ "start": 1024, "length": 11321, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
+[{ "start": 12345, "length": 2084807, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false}]
 *** done
diff --git a/tests/qemu-iotests/241.out b/tests/qemu-iotests/241.out
index 88e8cfcd7e..7946c286d5 100644
--- a/tests/qemu-iotests/241.out
+++ b/tests/qemu-iotests/241.out
@@ -6,8 +6,8 @@ exports available: 1
  export: ''
   size:  1024
   min block: 1
-[{ "start": 0, "length": 1000, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 1000, "length": 24, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET}]
+[{ "start": 0, "length": 1000, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 1000, "length": 24, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET}]
 1 KiB (0x400) bytes     allocated at offset 0 bytes (0x0)
 
 === Exporting unaligned raw image, forced server sector alignment ===
@@ -16,7 +16,7 @@ exports available: 1
  export: ''
   size:  1024
   min block: 512
-[{ "start": 0, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 1024, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 1 KiB (0x400) bytes     allocated at offset 0 bytes (0x0)
 WARNING: Image format was not specified for 'TEST_DIR/t.raw' and probing guessed raw.
          Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.
@@ -28,7 +28,7 @@ exports available: 1
  export: ''
   size:  1024
   min block: 1
-[{ "start": 0, "length": 1000, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 1000, "length": 24, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET}]
+[{ "start": 0, "length": 1000, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 1000, "length": 24, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET}]
 1 KiB (0x400) bytes     allocated at offset 0 bytes (0x0)
 *** done
diff --git a/tests/qemu-iotests/244.out b/tests/qemu-iotests/244.out
index 4815a489b0..f46cfe93f1 100644
--- a/tests/qemu-iotests/244.out
+++ b/tests/qemu-iotests/244.out
@@ -57,12 +57,12 @@ wrote 3145728/3145728 bytes at offset 3145728
 3 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 No errors were found on the image.
 
-[{ "start": 0, "length": 1048576, "depth": 0, "present": false, "zero": true, "data": false},
-{ "start": 1048576, "length": 1048576, "depth": 0, "present": true, "zero": false, "data": true, "offset": 1048576},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 4194304, "length": 1048576, "depth": 0, "present": true, "zero": true, "data": false, "offset": 4194304},
-{ "start": 5242880, "length": 1048576, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 6291456, "length": 60817408, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 1048576, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 1048576, "length": 1048576, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 1048576},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 4194304, "length": 1048576, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": 4194304},
+{ "start": 5242880, "length": 1048576, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 6291456, "length": 60817408, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 
 read 1048576/1048576 bytes at offset 0
 1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
@@ -94,10 +94,10 @@ wrote 3145728/3145728 bytes at offset 3145728
 3 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 No errors were found on the image.
 
-[{ "start": 0, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": 0},
-{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 4194304, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "offset": 4194304},
-{ "start": 6291456, "length": 60817408, "depth": 0, "present": true, "zero": false, "data": true, "offset": 6291456}]
+[{ "start": 0, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 0},
+{ "start": 2097152, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 4194304, "length": 2097152, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": 4194304},
+{ "start": 6291456, "length": 60817408, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 6291456}]
 
 read 1048576/1048576 bytes at offset 0
 1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
@@ -123,8 +123,8 @@ read 1048576/1048576 bytes at offset 0
 1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 Offset          Length          Mapped to       File
 0               0x100000        0               TEST_DIR/t.qcow2.data
-[{ "start": 0, "length": 1048576, "depth": 0, "present": true, "zero": false, "data": true, "offset": 0},
-{ "start": 1048576, "length": 66060288, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 1048576, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 0},
+{ "start": 1048576, "length": 66060288, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 
 === Copy offloading ===
 
diff --git a/tests/qemu-iotests/252.out b/tests/qemu-iotests/252.out
index c578129c25..b1aa94cb05 100644
--- a/tests/qemu-iotests/252.out
+++ b/tests/qemu-iotests/252.out
@@ -23,8 +23,8 @@ read 131072/131072 bytes at offset 131072
 read 131072/131072 bytes at offset 262144
 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
-[{ "start": 0, "length": 262144, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 262144, "length": 131072, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 262144, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 262144, "length": 131072, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 
 read 131072/131072 bytes at offset 0
 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
@@ -33,7 +33,7 @@ read 131072/131072 bytes at offset 131072
 read 131072/131072 bytes at offset 262144
 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
-[{ "start": 0, "length": 262144, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 262144, "length": 65536, "depth": 0, "present": true, "zero": true, "data": false},
-{ "start": 327680, "length": 65536, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 262144, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 262144, "length": 65536, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false},
+{ "start": 327680, "length": 65536, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 *** done
diff --git a/tests/qemu-iotests/253.out b/tests/qemu-iotests/253.out
index b3dca75a89..b458085adb 100644
--- a/tests/qemu-iotests/253.out
+++ b/tests/qemu-iotests/253.out
@@ -3,16 +3,16 @@ QA output created by 253
 === Check mapping of unaligned raw image ===
 
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048575
-[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 4096, "length": 1044480, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET}]
-[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 4096, "length": 1044480, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET}]
+[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 4096, "length": 1044480, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET}]
+[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 4096, "length": 1044480, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET}]
 wrote 65535/65535 bytes at offset 983040
 63.999 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 4096, "length": 978944, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 983040, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
-[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 4096, "length": 978944, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
-{ "start": 983040, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 4096, "length": 978944, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 983040, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
+[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 4096, "length": 978944, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET},
+{ "start": 983040, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 *** done
diff --git a/tests/qemu-iotests/274.out b/tests/qemu-iotests/274.out
index acd8b166a6..c2967335ca 100644
--- a/tests/qemu-iotests/274.out
+++ b/tests/qemu-iotests/274.out
@@ -20,18 +20,18 @@ read 1048576/1048576 bytes at offset 1048576
 0/1048576 bytes allocated at offset 1 MiB
 
 === Checking map ===
-[{ "start": 0, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": 327680}]
+[{ "start": 0, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 327680}]
 
 Offset          Length          Mapped to       File
 0               0x200000        0x50000         TEST_DIR/PID-base
 
-[{ "start": 0, "length": 1048576, "depth": 1, "present": true, "zero": false, "data": true, "offset": 327680}]
+[{ "start": 0, "length": 1048576, "depth": 1, "present": true, "zero": false, "data": true, "compressed": false, "offset": 327680}]
 
 Offset          Length          Mapped to       File
 0               0x100000        0x50000         TEST_DIR/PID-base
 
-[{ "start": 0, "length": 1048576, "depth": 2, "present": true, "zero": false, "data": true, "offset": 327680},
-{ "start": 1048576, "length": 1048576, "depth": 0, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 1048576, "depth": 2, "present": true, "zero": false, "data": true, "compressed": false, "offset": 327680},
+{ "start": 1048576, "length": 1048576, "depth": 0, "present": false, "zero": true, "data": false, "compressed": false}]
 
 Offset          Length          Mapped to       File
 0               0x100000        0x50000         TEST_DIR/PID-base
@@ -186,8 +186,8 @@ read 65536/65536 bytes at offset 5368709120
 1 GiB (0x40000000) bytes not allocated at offset 0 bytes (0x0)
 7 GiB (0x1c0000000) bytes     allocated at offset 1 GiB (0x40000000)
 
-[{ "start": 0, "length": 1073741824, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 1073741824, "length": 7516192768, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 1073741824, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 1073741824, "length": 7516192768, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === preallocation=metadata ===
 wrote 65536/65536 bytes at offset 33285996544
@@ -201,13 +201,13 @@ read 65536/65536 bytes at offset 33285996544
 30 GiB (0x780000000) bytes not allocated at offset 0 bytes (0x0)
 3 GiB (0xc0000000) bytes     allocated at offset 30 GiB (0x780000000)
 
-[{ "start": 0, "length": 32212254720, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 32212254720, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "offset": 327680},
-{ "start": 32749125632, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "offset": 537264128},
-{ "start": 33285996544, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "offset": 1074200576},
-{ "start": 33822867456, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "offset": 1611137024},
-{ "start": 34359738368, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "offset": 2148139008},
-{ "start": 34896609280, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "offset": 2685075456}]
+[{ "start": 0, "length": 32212254720, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 32212254720, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": 327680},
+{ "start": 32749125632, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": 537264128},
+{ "start": 33285996544, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": 1074200576},
+{ "start": 33822867456, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": 1611137024},
+{ "start": 34359738368, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": 2148139008},
+{ "start": 34896609280, "length": 536870912, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": 2685075456}]
 
 === preallocation=falloc ===
 wrote 65536/65536 bytes at offset 9437184
@@ -221,8 +221,8 @@ read 65536/65536 bytes at offset 9437184
 5 MiB (0x500000) bytes not allocated at offset 0 bytes (0x0)
 10 MiB (0xa00000) bytes     allocated at offset 5 MiB (0x500000)
 
-[{ "start": 0, "length": 5242880, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 5242880, "length": 10485760, "depth": 0, "present": true, "zero": false, "data": true, "offset": 327680}]
+[{ "start": 0, "length": 5242880, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 5242880, "length": 10485760, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 327680}]
 
 === preallocation=full ===
 wrote 65536/65536 bytes at offset 11534336
@@ -236,8 +236,8 @@ read 65536/65536 bytes at offset 11534336
 8 MiB (0x800000) bytes not allocated at offset 0 bytes (0x0)
 4 MiB (0x400000) bytes     allocated at offset 8 MiB (0x800000)
 
-[{ "start": 0, "length": 8388608, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 8388608, "length": 4194304, "depth": 0, "present": true, "zero": false, "data": true, "offset": 327680}]
+[{ "start": 0, "length": 8388608, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 8388608, "length": 4194304, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 327680}]
 
 === preallocation=off ===
 wrote 65536/65536 bytes at offset 259072
@@ -251,9 +251,9 @@ read 65536/65536 bytes at offset 259072
 192 KiB (0x30000) bytes not allocated at offset 0 bytes (0x0)
 320 KiB (0x50000) bytes     allocated at offset 192 KiB (0x30000)
 
-[{ "start": 0, "length": 196608, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 196608, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true, "offset": 327680},
-{ "start": 262144, "length": 262144, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 196608, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 196608, "length": 65536, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 327680},
+{ "start": 262144, "length": 262144, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === preallocation=off ===
 wrote 65536/65536 bytes at offset 344064
@@ -267,8 +267,8 @@ read 65536/65536 bytes at offset 344064
 256 KiB (0x40000) bytes not allocated at offset 0 bytes (0x0)
 256 KiB (0x40000) bytes     allocated at offset 256 KiB (0x40000)
 
-[{ "start": 0, "length": 262144, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 262144, "length": 262144, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 262144, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 262144, "length": 262144, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
 === preallocation=off ===
 wrote 65536/65536 bytes at offset 446464
@@ -282,6 +282,6 @@ read 65536/65536 bytes at offset 446464
 256 KiB (0x40000) bytes not allocated at offset 0 bytes (0x0)
 244 KiB (0x3d000) bytes     allocated at offset 256 KiB (0x40000)
 
-[{ "start": 0, "length": 262144, "depth": 1, "present": false, "zero": true, "data": false},
-{ "start": 262144, "length": 249856, "depth": 0, "present": true, "zero": true, "data": false}]
+[{ "start": 0, "length": 262144, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false},
+{ "start": 262144, "length": 249856, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false}]
 
diff --git a/tests/qemu-iotests/tests/nbd-qemu-allocation.out b/tests/qemu-iotests/tests/nbd-qemu-allocation.out
index 9d938db24e..138eb09c6d 100644
--- a/tests/qemu-iotests/tests/nbd-qemu-allocation.out
+++ b/tests/qemu-iotests/tests/nbd-qemu-allocation.out
@@ -11,9 +11,9 @@ wrote 2097152/2097152 bytes at offset 1048576
 
 === Check allocation over NBD ===
 
-[{ "start": 0, "length": 1048576, "depth": 1, "present": true, "zero": false, "data": true, "offset": 327680},
-{ "start": 1048576, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": 327680},
-{ "start": 3145728, "length": 1048576, "depth": 1, "present": false, "zero": true, "data": false}]
+[{ "start": 0, "length": 1048576, "depth": 1, "present": true, "zero": false, "data": true, "compressed": false, "offset": 327680},
+{ "start": 1048576, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 327680},
+{ "start": 3145728, "length": 1048576, "depth": 1, "present": false, "zero": true, "data": false, "compressed": false}]
 exports available: 1
  export: ''
   size:  4194304
@@ -24,9 +24,9 @@ exports available: 1
   available meta contexts: 2
    base:allocation
    qemu:allocation-depth
-[{ "start": 0, "length": 3145728, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 3145728, "length": 1048576, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET}]
-[{ "start": 0, "length": 1048576, "depth": 0, "present": true, "zero": true, "data": true, "offset": OFFSET},
-{ "start": 1048576, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false},
-{ "start": 3145728, "length": 1048576, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 3145728, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 3145728, "length": 1048576, "depth": 0, "present": true, "zero": true, "data": false, "compressed": false, "offset": OFFSET}]
+[{ "start": 0, "length": 1048576, "depth": 0, "present": true, "zero": true, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 1048576, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false},
+{ "start": 3145728, "length": 1048576, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 *** done
diff --git a/tests/qemu-iotests/tests/qemu-img-bitmaps.out b/tests/qemu-iotests/tests/qemu-img-bitmaps.out
index e851f0320e..74b81f703b 100644
--- a/tests/qemu-iotests/tests/qemu-img-bitmaps.out
+++ b/tests/qemu-iotests/tests/qemu-img-bitmaps.out
@@ -103,18 +103,18 @@ Format specific information:
 
 === Check bitmap contents ===
 
-[{ "start": 0, "length": 3145728, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 3145728, "length": 1048576, "depth": 0, "present": false, "zero": false, "data": false},
-{ "start": 4194304, "length": 6291456, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
-[{ "start": 0, "length": 1048576, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 1048576, "length": 1048576, "depth": 0, "present": false, "zero": false, "data": false},
-{ "start": 2097152, "length": 8388608, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
-[{ "start": 0, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 2097152, "length": 1048576, "depth": 0, "present": false, "zero": false, "data": false},
-{ "start": 3145728, "length": 7340032, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
-[{ "start": 0, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
-{ "start": 2097152, "length": 1048576, "depth": 0, "present": false, "zero": false, "data": false},
-{ "start": 3145728, "length": 7340032, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+[{ "start": 0, "length": 3145728, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 3145728, "length": 1048576, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false},
+{ "start": 4194304, "length": 6291456, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
+[{ "start": 0, "length": 1048576, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 1048576, "length": 1048576, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false},
+{ "start": 2097152, "length": 8388608, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
+[{ "start": 0, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 2097152, "length": 1048576, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false},
+{ "start": 3145728, "length": 7340032, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
+[{ "start": 0, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET},
+{ "start": 2097152, "length": 1048576, "depth": 0, "present": false, "zero": false, "data": false, "compressed": false},
+{ "start": 3145728, "length": 7340032, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": OFFSET}]
 
 === Check handling of inconsistent bitmap ===
 
-- 
2.41.0

[PULL 24/28] block: remove AIOCBInfo->get_aio_context()

[Kevin Wolf]

From: Stefan Hajnoczi <stefanha@redhat.com>

The synchronous bdrv_aio_cancel() function needs the acb's AioContext so
it can call aio_poll() to wait for cancellation.

It turns out that all users run under the BQL in the main AioContext, so
this callback is not needed.

Remove the callback, mark bdrv_aio_cancel() GLOBAL_STATE_CODE just like
its blk_aio_cancel() caller, and poll the main loop AioContext.

The purpose of this cleanup is to identify bdrv_aio_cancel() as an API
that does not work with the multi-queue block layer.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230912231037.826804-2-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/aio.h                |  1 -
 include/block/block-global-state.h |  2 ++
 include/block/block-io.h           |  1 -
 block/block-backend.c              | 17 -----------------
 block/io.c                         | 23 ++++++++---------------
 hw/nvme/ctrl.c                     |  7 -------
 softmmu/dma-helpers.c              |  8 --------
 util/thread-pool.c                 |  8 --------
 8 files changed, 10 insertions(+), 57 deletions(-)

diff --git a/include/block/aio.h b/include/block/aio.h
index 32042e8905..bcc165c974 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -31,7 +31,6 @@ typedef void BlockCompletionFunc(void *opaque, int ret);
 
 typedef struct AIOCBInfo {
     void (*cancel_async)(BlockAIOCB *acb);
-    AioContext *(*get_aio_context)(BlockAIOCB *acb);
     size_t aiocb_size;
 } AIOCBInfo;
 
diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index f31660c7b1..6061220a6c 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -185,6 +185,8 @@ void bdrv_drain_all_begin_nopoll(void);
 void bdrv_drain_all_end(void);
 void bdrv_drain_all(void);
 
+void bdrv_aio_cancel(BlockAIOCB *acb);
+
 int bdrv_has_zero_init_1(BlockDriverState *bs);
 int bdrv_has_zero_init(BlockDriverState *bs);
 BlockDriverState *bdrv_find_node(const char *node_name);
diff --git a/include/block/block-io.h b/include/block/block-io.h
index 6db48f2d35..f1c796a1ce 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -101,7 +101,6 @@ bdrv_co_delete_file_noerr(BlockDriverState *bs);
 
 
 /* async block I/O */
-void bdrv_aio_cancel(BlockAIOCB *acb);
 void bdrv_aio_cancel_async(BlockAIOCB *acb);
 
 /* sg packet commands */
diff --git a/block/block-backend.c b/block/block-backend.c
index c2636f4351..24b9449712 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -33,8 +33,6 @@
 
 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
 
-static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb);
-
 typedef struct BlockBackendAioNotifier {
     void (*attached_aio_context)(AioContext *new_context, void *opaque);
     void (*detach_aio_context)(void *opaque);
@@ -103,7 +101,6 @@ typedef struct BlockBackendAIOCB {
 } BlockBackendAIOCB;
 
 static const AIOCBInfo block_backend_aiocb_info = {
-    .get_aio_context = blk_aiocb_get_aio_context,
     .aiocb_size = sizeof(BlockBackendAIOCB),
 };
 
@@ -1562,16 +1559,8 @@ typedef struct BlkAioEmAIOCB {
     bool has_returned;
 } BlkAioEmAIOCB;
 
-static AioContext *blk_aio_em_aiocb_get_aio_context(BlockAIOCB *acb_)
-{
-    BlkAioEmAIOCB *acb = container_of(acb_, BlkAioEmAIOCB, common);
-
-    return blk_get_aio_context(acb->rwco.blk);
-}
-
 static const AIOCBInfo blk_aio_em_aiocb_info = {
     .aiocb_size         = sizeof(BlkAioEmAIOCB),
-    .get_aio_context    = blk_aio_em_aiocb_get_aio_context,
 };
 
 static void blk_aio_complete(BlkAioEmAIOCB *acb)
@@ -2451,12 +2440,6 @@ AioContext *blk_get_aio_context(BlockBackend *blk)
     return blk->ctx;
 }
 
-static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb)
-{
-    BlockBackendAIOCB *blk_acb = DO_UPCAST(BlockBackendAIOCB, common, acb);
-    return blk_get_aio_context(blk_acb->blk);
-}
-
 int blk_set_aio_context(BlockBackend *blk, AioContext *new_context,
                         Error **errp)
 {
diff --git a/block/io.c b/block/io.c
index ba23a9bcd3..209a6da0c8 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2950,25 +2950,18 @@ int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
 /**************************************************************/
 /* async I/Os */
 
+/**
+ * Synchronously cancels an acb. Must be called with the BQL held and the acb
+ * must be processed with the BQL held too (IOThreads are not allowed).
+ *
+ * Use bdrv_aio_cancel_async() instead when possible.
+ */
 void bdrv_aio_cancel(BlockAIOCB *acb)
 {
-    IO_CODE();
+    GLOBAL_STATE_CODE();
     qemu_aio_ref(acb);
     bdrv_aio_cancel_async(acb);
-    while (acb->refcnt > 1) {
-        if (acb->aiocb_info->get_aio_context) {
-            aio_poll(acb->aiocb_info->get_aio_context(acb), true);
-        } else if (acb->bs) {
-            /* qemu_aio_ref and qemu_aio_unref are not thread-safe, so
-             * assert that we're not using an I/O thread.  Thread-safe
-             * code should use bdrv_aio_cancel_async exclusively.
-             */
-            assert(bdrv_get_aio_context(acb->bs) == qemu_get_aio_context());
-            aio_poll(bdrv_get_aio_context(acb->bs), true);
-        } else {
-            abort();
-        }
-    }
+    AIO_WAIT_WHILE_UNLOCKED(NULL, acb->refcnt > 1);
     qemu_aio_unref(acb);
 }
 
diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index 90687b168a..03265359ff 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -2130,11 +2130,6 @@ static inline bool nvme_is_write(NvmeRequest *req)
            rw->opcode == NVME_CMD_WRITE_ZEROES;
 }
 
-static AioContext *nvme_get_aio_context(BlockAIOCB *acb)
-{
-    return qemu_get_aio_context();
-}
-
 static void nvme_misc_cb(void *opaque, int ret)
 {
     NvmeRequest *req = opaque;
@@ -3302,7 +3297,6 @@ static void nvme_flush_cancel(BlockAIOCB *acb)
 static const AIOCBInfo nvme_flush_aiocb_info = {
     .aiocb_size = sizeof(NvmeFlushAIOCB),
     .cancel_async = nvme_flush_cancel,
-    .get_aio_context = nvme_get_aio_context,
 };
 
 static void nvme_do_flush(NvmeFlushAIOCB *iocb);
@@ -6478,7 +6472,6 @@ static void nvme_format_cancel(BlockAIOCB *aiocb)
 static const AIOCBInfo nvme_format_aiocb_info = {
     .aiocb_size = sizeof(NvmeFormatAIOCB),
     .cancel_async = nvme_format_cancel,
-    .get_aio_context = nvme_get_aio_context,
 };
 
 static void nvme_format_set(NvmeNamespace *ns, uint8_t lbaf, uint8_t mset,
diff --git a/softmmu/dma-helpers.c b/softmmu/dma-helpers.c
index 2463964805..36211acc7e 100644
--- a/softmmu/dma-helpers.c
+++ b/softmmu/dma-helpers.c
@@ -206,17 +206,9 @@ static void dma_aio_cancel(BlockAIOCB *acb)
     }
 }
 
-static AioContext *dma_get_aio_context(BlockAIOCB *acb)
-{
-    DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
-
-    return dbs->ctx;
-}
-
 static const AIOCBInfo dma_aiocb_info = {
     .aiocb_size         = sizeof(DMAAIOCB),
     .cancel_async       = dma_aio_cancel,
-    .get_aio_context    = dma_get_aio_context,
 };
 
 BlockAIOCB *dma_blk_io(AioContext *ctx,
diff --git a/util/thread-pool.c b/util/thread-pool.c
index e3d8292d14..22f9ba3286 100644
--- a/util/thread-pool.c
+++ b/util/thread-pool.c
@@ -228,17 +228,9 @@ static void thread_pool_cancel(BlockAIOCB *acb)
 
 }
 
-static AioContext *thread_pool_get_aio_context(BlockAIOCB *acb)
-{
-    ThreadPoolElement *elem = (ThreadPoolElement *)acb;
-    ThreadPool *pool = elem->pool;
-    return pool->ctx;
-}
-
 static const AIOCBInfo thread_pool_aiocb_info = {
     .aiocb_size         = sizeof(ThreadPoolElement),
     .cancel_async       = thread_pool_cancel,
-    .get_aio_context    = thread_pool_get_aio_context,
 };
 
 BlockAIOCB *thread_pool_submit_aio(ThreadPoolFunc *func, void *arg,
-- 
2.41.0

[PULL 25/28] test-bdrv-drain: avoid race with BH in IOThread drain test

[Kevin Wolf]

From: Stefan Hajnoczi <stefanha@redhat.com>

This patch fixes a race condition in test-bdrv-drain that is difficult
to reproduce. test-bdrv-drain sometimes fails without an error message
on the block pull request sent by Kevin Wolf on Sep 4, 2023. I was able
to reproduce it locally and found that "block-backend: process I/O in
the current AioContext" (in this patch series) is the first commit where
it reproduces.

I do not know why "block-backend: process I/O in the current AioContext"
exposes this bug. It might be related to the fact that the test's preadv
request runs in the main thread instead of IOThread a after my commit.
That might simply change the timing of the test.

Now on to the race condition in test-bdrv-drain. The main thread
schedules a BH in IOThread a and then drains the BDS:

  aio_bh_schedule_oneshot(ctx_a, test_iothread_main_thread_bh, &data);

  /* The request is running on the IOThread a. Draining its block device
   * will make sure that it has completed as far as the BDS is concerned,
   * but the drain in this thread can continue immediately after
   * bdrv_dec_in_flight() and aio_ret might be assigned only slightly
   * later. */
  do_drain_begin(drain_type, bs);

If the BH completes before do_drain_begin() then there is nothing to
worry about.

If the BH invokes bdrv_flush() before do_drain_begin(), then
do_drain_begin() waits for it to complete.

The problematic case is when do_drain_begin() runs before the BH enters
bdrv_flush(). Then do_drain_begin() misses the BH and the drain
mechanism has failed in quiescing I/O.

Fix this by incrementing the in_flight counter so that do_drain_begin()
waits for test_iothread_main_thread_bh().

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230912231037.826804-3-stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 tests/unit/test-bdrv-drain.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index b040a73bb9..0b603e7c57 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -512,6 +512,7 @@ static void test_iothread_main_thread_bh(void *opaque)
      * executed during drain, otherwise this would deadlock. */
     aio_context_acquire(bdrv_get_aio_context(data->bs));
     bdrv_flush(data->bs);
+    bdrv_dec_in_flight(data->bs); /* incremented by test_iothread_common() */
     aio_context_release(bdrv_get_aio_context(data->bs));
 }
 
@@ -583,6 +584,13 @@ static void test_iothread_common(enum drain_type drain_type, int drain_thread)
             aio_context_acquire(ctx_a);
         }
 
+        /*
+         * Increment in_flight so that do_drain_begin() waits for
+         * test_iothread_main_thread_bh(). This prevents the race between
+         * test_iothread_main_thread_bh() in IOThread a and do_drain_begin() in
+         * this thread. test_iothread_main_thread_bh() decrements in_flight.
+         */
+        bdrv_inc_in_flight(bs);
         aio_bh_schedule_oneshot(ctx_a, test_iothread_main_thread_bh, &data);
 
         /* The request is running on the IOThread a. Draining its block device
-- 
2.41.0

[PULL 26/28] block-backend: process I/O in the current AioContext

[Kevin Wolf]

From: Stefan Hajnoczi <stefanha@redhat.com>

Switch blk_aio_*() APIs over to multi-queue by using
qemu_get_current_aio_context() instead of blk_get_aio_context(). This
change will allow devices to process I/O in multiple IOThreads in the
future.

I audited existing blk_aio_*() callers:
- migration/block.c: blk_mig_lock() protects the data accessed by the
  completion callback.
- The remaining emulated devices and exports run with
  qemu_get_aio_context() == blk_get_aio_context().

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230912231037.826804-4-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/block-backend.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index 24b9449712..6f0a6084f1 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1547,7 +1547,7 @@ BlockAIOCB *blk_abort_aio_request(BlockBackend *blk,
     acb->blk = blk;
     acb->ret = ret;
 
-    replay_bh_schedule_oneshot_event(blk_get_aio_context(blk),
+    replay_bh_schedule_oneshot_event(qemu_get_current_aio_context(),
                                      error_callback_bh, acb);
     return &acb->common;
 }
@@ -1601,11 +1601,11 @@ static BlockAIOCB *blk_aio_prwv(BlockBackend *blk, int64_t offset,
     acb->has_returned = false;
 
     co = qemu_coroutine_create(co_entry, acb);
-    aio_co_enter(blk_get_aio_context(blk), co);
+    aio_co_enter(qemu_get_current_aio_context(), co);
 
     acb->has_returned = true;
     if (acb->rwco.ret != NOT_DONE) {
-        replay_bh_schedule_oneshot_event(blk_get_aio_context(blk),
+        replay_bh_schedule_oneshot_event(qemu_get_current_aio_context(),
                                          blk_aio_complete_bh, acb);
     }
 
-- 
2.41.0

[PULL 27/28] block-backend: process zoned requests in the current AioContext

[Kevin Wolf]

From: Stefan Hajnoczi <stefanha@redhat.com>

Process zoned requests in the current thread's AioContext instead of in
the BlockBackend's AioContext.

There is no need to use the BlockBackend's AioContext thanks to CoMutex
bs->wps->colock, which protects zone metadata.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230912231037.826804-5-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/block-backend.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index 6f0a6084f1..9dbdbe5545 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1907,11 +1907,11 @@ BlockAIOCB *blk_aio_zone_report(BlockBackend *blk, int64_t offset,
     acb->has_returned = false;
 
     co = qemu_coroutine_create(blk_aio_zone_report_entry, acb);
-    aio_co_enter(blk_get_aio_context(blk), co);
+    aio_co_enter(qemu_get_current_aio_context(), co);
 
     acb->has_returned = true;
     if (acb->rwco.ret != NOT_DONE) {
-        replay_bh_schedule_oneshot_event(blk_get_aio_context(blk),
+        replay_bh_schedule_oneshot_event(qemu_get_current_aio_context(),
                                          blk_aio_complete_bh, acb);
     }
 
@@ -1948,11 +1948,11 @@ BlockAIOCB *blk_aio_zone_mgmt(BlockBackend *blk, BlockZoneOp op,
     acb->has_returned = false;
 
     co = qemu_coroutine_create(blk_aio_zone_mgmt_entry, acb);
-    aio_co_enter(blk_get_aio_context(blk), co);
+    aio_co_enter(qemu_get_current_aio_context(), co);
 
     acb->has_returned = true;
     if (acb->rwco.ret != NOT_DONE) {
-        replay_bh_schedule_oneshot_event(blk_get_aio_context(blk),
+        replay_bh_schedule_oneshot_event(qemu_get_current_aio_context(),
                                          blk_aio_complete_bh, acb);
     }
 
@@ -1988,10 +1988,10 @@ BlockAIOCB *blk_aio_zone_append(BlockBackend *blk, int64_t *offset,
     acb->has_returned = false;
 
     co = qemu_coroutine_create(blk_aio_zone_append_entry, acb);
-    aio_co_enter(blk_get_aio_context(blk), co);
+    aio_co_enter(qemu_get_current_aio_context(), co);
     acb->has_returned = true;
     if (acb->rwco.ret != NOT_DONE) {
-        replay_bh_schedule_oneshot_event(blk_get_aio_context(blk),
+        replay_bh_schedule_oneshot_event(qemu_get_current_aio_context(),
                                          blk_aio_complete_bh, acb);
     }
 
-- 
2.41.0

[PULL 28/28] block-coroutine-wrapper: use qemu_get_current_aio_context()

[Kevin Wolf]

From: Stefan Hajnoczi <stefanha@redhat.com>

Use qemu_get_current_aio_context() in mixed wrappers and coroutine
wrappers so that code runs in the caller's AioContext instead of moving
to the BlockDriverState's AioContext. This change is necessary for the
multi-queue block layer where any thread can call into the block layer.

Most wrappers are IO_CODE where it's safe to use the current AioContext
nowadays. BlockDrivers and the core block layer use their own locks and
no longer depend on the AioContext lock for thread-safety.

The bdrv_create() wrapper invokes GLOBAL_STATE code. Using the current
AioContext is safe because this code is only called with the BQL held
from the main loop thread.

The output of qemu-iotests 051 is sensitive to event loop activity.
Update the output because the monitor BH runs at a different time,
causing prompts to be printed differently in the output.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230912231037.826804-6-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 scripts/block-coroutine-wrapper.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/scripts/block-coroutine-wrapper.py b/scripts/block-coroutine-wrapper.py
index 685d0b4ed4..66cda6b8db 100644
--- a/scripts/block-coroutine-wrapper.py
+++ b/scripts/block-coroutine-wrapper.py
@@ -91,8 +91,6 @@ def __init__(self, wrapper_type: str, return_type: str, name: str,
                 raise ValueError(f"no_co function can't be rdlock: {self.name}")
             self.target_name = f'{subsystem}_{subname}'
 
-        self.ctx = self.gen_ctx()
-
         self.get_result = 's->ret = '
         self.ret = 'return s.ret;'
         self.co_ret = 'return '
@@ -166,7 +164,7 @@ def create_mixed_wrapper(func: FuncDecl) -> str:
         {func.co_ret}{name}({ func.gen_list('{name}') });
     }} else {{
         {struct_name} s = {{
-            .poll_state.ctx = {func.ctx},
+            .poll_state.ctx = qemu_get_current_aio_context(),
             .poll_state.in_progress = true,
 
 { func.gen_block('            .{name} = {name},') }
@@ -190,7 +188,7 @@ def create_co_wrapper(func: FuncDecl) -> str:
 {func.return_type} {func.name}({ func.gen_list('{decl}') })
 {{
     {struct_name} s = {{
-        .poll_state.ctx = {func.ctx},
+        .poll_state.ctx = qemu_get_current_aio_context(),
         .poll_state.in_progress = true,
 
 { func.gen_block('        .{name} = {name},') }
-- 
2.41.0

Re: [PULL 00/28] Block layer patches

[Stefan Hajnoczi]

Hi Kevin,
The following CI failure looks like it is related to this pull
request. Please take a look:
https://gitlab.com/qemu-project/qemu/-/jobs/5112083994

▶ 823/840 qcow2 iothreads-commit-active FAIL
823/840 qemu:block / io-qcow2-iothreads-commit-active ERROR 6.16s exit status 1
>>> MALLOC_PERTURB_=184 PYTHON=/home/gitlab-runner/builds/E8PpwMky/0/qemu-project/qemu/build/pyvenv/bin/python3 /home/gitlab-runner/builds/E8PpwMky/0/qemu-project/qemu/build/pyvenv/bin/python3 /home/gitlab-runner/builds/E8PpwMky/0/qemu-project/qemu/build/../tests/qemu-iotests/check -tap -qcow2 iothreads-commit-active --source-dir /home/gitlab-runner/builds/E8PpwMky/0/qemu-project/qemu/tests/qemu-iotests --build-dir /home/gitlab-runner/builds/E8PpwMky/0/qemu-project/qemu/build/tests/qemu-iotests
――――――――――――――――――――――――――――――――――――― ✀ ―――――――――――――――――――――――――――――――――――――
stderr:
--- /home/gitlab-runner/builds/E8PpwMky/0/qemu-project/qemu/tests/qemu-iotests/tests/iothreads-commit-active.out
+++ /home/gitlab-runner/builds/E8PpwMky/0/qemu-project/qemu/build/scratch/qcow2-file-iothreads-commit-active/iothreads-commit-active.out.bad
@@ -18,6 +18,35 @@
{"execute": "job-complete", "arguments": {"id": "job1"}}
{"return": {}}
{"data": {"device": "job1", "len": 131072, "offset": 131072, "speed":
0, "type": "commit"}, "event": "BLOCK_JOB_READY", "timestamp":
{"microseconds": "USECS", "seconds": "SECS"}}
-{"data": {"device": "job1", "len": 131072, "offset": 131072, "speed":
0, "type": "commit"}, "event": "BLOCK_JOB_COMPLETED", "timestamp":
{"microseconds": "USECS", "seconds": "SECS"}}
-{"execute": "job-dismiss", "arguments": {"id": "job1"}}
-{"return": {}}
+Traceback (most recent call last):
+ File "/home/gitlab-runner/builds/E8PpwMky/0/qemu-project/qemu/python/qemu/qmp/events.py",
line 557, in get
+ return await self._queue.get()
+ File "/usr/lib/python3.10/asyncio/queues.py", line 159, in get
+ await getter
+asyncio.exceptions.CancelledError
+
+During handling of the above exception, another exception occurred:
+
+Traceback (most recent call last):
+ File "/usr/lib/python3.10/asyncio/tasks.py", line 456, in wait_for
+ return fut.result()
+asyncio.exceptions.CancelledError
+
+The above exception was the direct cause of the following exception:

On Fri, 15 Sept 2023 at 10:45, Kevin Wolf <kwolf@redhat.com> wrote:
>
> The following changes since commit 005ad32358f12fe9313a4a01918a55e60d4f39e5:
>
>   Merge tag 'pull-tpm-2023-09-12-3' of https://github.com/stefanberger/qemu-tpm into staging (2023-09-13 13:41:57 -0400)
>
> are available in the Git repository at:
>
>   https://repo.or.cz/qemu/kevin.git tags/for-upstream
>
> for you to fetch changes up to 5d96864b73225ee61b0dad7e928f0cddf14270fc:
>
>   block-coroutine-wrapper: use qemu_get_current_aio_context() (2023-09-15 15:49:14 +0200)
>
> ----------------------------------------------------------------
> Block layer patches
>
> - Graph locking part 4 (node management)
> - qemu-img map: report compressed data blocks
> - block-backend: process I/O in the current AioContext
>
> ----------------------------------------------------------------
> Andrey Drobyshev via (2):
>       block: add BDRV_BLOCK_COMPRESSED flag for bdrv_block_status()
>       qemu-img: map: report compressed data blocks
>
> Kevin Wolf (21):
>       block: Remove unused BlockReopenQueueEntry.perms_checked
>       preallocate: Factor out preallocate_truncate_to_real_size()
>       preallocate: Don't poll during permission updates
>       block: Take AioContext lock for bdrv_append() more consistently
>       block: Introduce bdrv_schedule_unref()
>       block-coroutine-wrapper: Add no_co_wrapper_bdrv_wrlock functions
>       block-coroutine-wrapper: Allow arbitrary parameter names
>       block: Mark bdrv_replace_child_noperm() GRAPH_WRLOCK
>       block: Mark bdrv_replace_child_tran() GRAPH_WRLOCK
>       block: Mark bdrv_attach_child_common() GRAPH_WRLOCK
>       block: Call transaction callbacks with lock held
>       block: Mark bdrv_attach_child() GRAPH_WRLOCK
>       block: Mark bdrv_parent_perms_conflict() and callers GRAPH_RDLOCK
>       block: Mark bdrv_get_cumulative_perm() and callers GRAPH_RDLOCK
>       block: Mark bdrv_child_perm() GRAPH_RDLOCK
>       block: Mark bdrv_parent_cb_change_media() GRAPH_RDLOCK
>       block: Take graph rdlock in bdrv_drop_intermediate()
>       block: Take graph rdlock in bdrv_change_aio_context()
>       block: Mark bdrv_root_unref_child() GRAPH_WRLOCK
>       block: Mark bdrv_unref_child() GRAPH_WRLOCK
>       block: Mark bdrv_add/del_child() and caller GRAPH_WRLOCK
>
> Stefan Hajnoczi (5):
>       block: remove AIOCBInfo->get_aio_context()
>       test-bdrv-drain: avoid race with BH in IOThread drain test
>       block-backend: process I/O in the current AioContext
>       block-backend: process zoned requests in the current AioContext
>       block-coroutine-wrapper: use qemu_get_current_aio_context()
>
>  qapi/block-core.json                             |   6 +-
>  include/block/aio.h                              |   1 -
>  include/block/block-common.h                     |   7 +
>  include/block/block-global-state.h               |  32 +-
>  include/block/block-io.h                         |   1 -
>  include/block/block_int-common.h                 |  34 +-
>  include/block/block_int-global-state.h           |  14 +-
>  include/sysemu/block-backend-global-state.h      |   4 +-
>  block.c                                          | 348 +++++++---
>  block/blklogwrites.c                             |   4 +
>  block/blkverify.c                                |   2 +
>  block/block-backend.c                            |  64 +-
>  block/copy-before-write.c                        |  10 +-
>  block/crypto.c                                   |   6 +-
>  block/graph-lock.c                               |  26 +-
>  block/io.c                                       |  23 +-
>  block/mirror.c                                   |   8 +
>  block/preallocate.c                              | 133 ++--
>  block/qcow.c                                     |   5 +-
>  block/qcow2.c                                    |   7 +-
>  block/quorum.c                                   |  23 +-
>  block/replication.c                              |   9 +
>  block/snapshot.c                                 |   2 +
>  block/stream.c                                   |  20 +-
>  block/vmdk.c                                     |  15 +
>  blockdev.c                                       |  23 +-
>  blockjob.c                                       |   2 +
>  hw/nvme/ctrl.c                                   |   7 -
>  qemu-img.c                                       |   8 +-
>  softmmu/dma-helpers.c                            |   8 -
>  tests/unit/test-bdrv-drain.c                     |  31 +-
>  tests/unit/test-bdrv-graph-mod.c                 |  20 +
>  tests/unit/test-block-iothread.c                 |   3 +
>  util/thread-pool.c                               |   8 -
>  scripts/block-coroutine-wrapper.py               |  24 +-
>  tests/qemu-iotests/051.pc.out                    |   6 +-
>  tests/qemu-iotests/122.out                       |  84 +--
>  tests/qemu-iotests/146.out                       | 780 +++++++++++------------
>  tests/qemu-iotests/154.out                       | 194 +++---
>  tests/qemu-iotests/179.out                       | 178 +++---
>  tests/qemu-iotests/209.out                       |   4 +-
>  tests/qemu-iotests/221.out                       |  16 +-
>  tests/qemu-iotests/223.out                       |  60 +-
>  tests/qemu-iotests/241.out                       |  10 +-
>  tests/qemu-iotests/244.out                       |  24 +-
>  tests/qemu-iotests/252.out                       |  10 +-
>  tests/qemu-iotests/253.out                       |  20 +-
>  tests/qemu-iotests/274.out                       |  48 +-
>  tests/qemu-iotests/tests/nbd-qemu-allocation.out |  16 +-
>  tests/qemu-iotests/tests/qemu-img-bitmaps.out    |  24 +-
>  50 files changed, 1376 insertions(+), 1036 deletions(-)
>
>

Re: [PULL 00/28] Block layer patches

[Stefan Hajnoczi]

Hi Kevin,
I believe that my own commit "block-coroutine-wrapper: use
qemu_get_current_aio_context()" breaks this test. The failure is
non-deterministic (happens about 1 out of 4 runs).

It seems the job hangs and the test times out in vm.run_job('job1', wait=5.0).

I haven't debugged it yet but wanted to share this information to save
some time. Tomorrow I'll investigate further.

Stefan

Re: [PULL 00/28] Block layer patches

[Kevin Wolf]

Am 18.09.2023 um 20:56 hat Stefan Hajnoczi geschrieben:
> Hi Kevin,
> I believe that my own commit "block-coroutine-wrapper: use
> qemu_get_current_aio_context()" breaks this test. The failure is
> non-deterministic (happens about 1 out of 4 runs).
> 
> It seems the job hangs and the test times out in vm.run_job('job1', wait=5.0).
> 
> I haven't debugged it yet but wanted to share this information to save
> some time. Tomorrow I'll investigate further.

Yes, it's relatively easily reproducible if I run the test in a loop,
and I can't seem to reproduce it without the last patch. Should I
unstage the full series again, or do you think that the last patch is
really optional this time?

However, I'm unsure how the stack traces I'm seeing are related to your
patch. Maybe it just made an existing bug more likely to be triggered?

What I'm seeing is that the reader lock is held by an iothread that is
waiting for its AioContext lock to make progress:

Thread 3 (Thread 0x7f811e9346c0 (LWP 26390) "qemu-system-x86"):
#0  0x00007f81250aaf80 in __lll_lock_wait () at /lib64/libc.so.6
#1  0x00007f81250b149a in pthread_mutex_lock@@GLIBC_2.2.5 () at /lib64/libc.so.6
#2  0x000055b7b170967e in qemu_mutex_lock_impl (mutex=0x55b7b34e3080, file=0x55b7b199e1f7 "../util/async.c", line=728) at ../util/qemu-thread-posix.c:94
#3  0x000055b7b1709953 in qemu_rec_mutex_lock_impl (mutex=0x55b7b34e3080, file=0x55b7b199e1f7 "../util/async.c", line=728) at ../util/qemu-thread-posix.c:149
#4  0x000055b7b1728318 in aio_context_acquire (ctx=0x55b7b34e3020) at ../util/async.c:728
#5  0x000055b7b1727c49 in co_schedule_bh_cb (opaque=0x55b7b34e3020) at ../util/async.c:565
#6  0x000055b7b1726f1c in aio_bh_call (bh=0x55b7b34e2e70) at ../util/async.c:169
#7  0x000055b7b17270ee in aio_bh_poll (ctx=0x55b7b34e3020) at ../util/async.c:216
#8  0x000055b7b170351d in aio_poll (ctx=0x55b7b34e3020, blocking=true) at ../util/aio-posix.c:722
#9  0x000055b7b1518604 in iothread_run (opaque=0x55b7b2904460) at ../iothread.c:63
#10 0x000055b7b170a955 in qemu_thread_start (args=0x55b7b34e36b0) at ../util/qemu-thread-posix.c:541
#11 0x00007f81250ae15d in start_thread () at /lib64/libc.so.6
#12 0x00007f812512fc00 in clone3 () at /lib64/libc.so.6

On the other hand, the main thread wants to acquire the writer lock,
but it holds the AioContext lock of the iothread (it takes it in
job_prepare_locked()):

Thread 1 (Thread 0x7f811f4b7b00 (LWP 26388) "qemu-system-x86"):
#0  0x00007f8125122356 in ppoll () at /lib64/libc.so.6
#1  0x000055b7b172eae0 in qemu_poll_ns (fds=0x55b7b34ec910, nfds=1, timeout=-1) at ../util/qemu-timer.c:339
#2  0x000055b7b1704ebd in fdmon_poll_wait (ctx=0x55b7b3269210, ready_list=0x7ffc90b05680, timeout=-1) at ../util/fdmon-poll.c:79
#3  0x000055b7b1703284 in aio_poll (ctx=0x55b7b3269210, blocking=true) at ../util/aio-posix.c:670
#4  0x000055b7b1567c3b in bdrv_graph_wrlock (bs=0x0) at ../block/graph-lock.c:145
#5  0x000055b7b1554c1c in blk_remove_bs (blk=0x55b7b4425800) at ../block/block-backend.c:916
#6  0x000055b7b1554779 in blk_delete (blk=0x55b7b4425800) at ../block/block-backend.c:497
#7  0x000055b7b1554133 in blk_unref (blk=0x55b7b4425800) at ../block/block-backend.c:557
#8  0x000055b7b157a149 in mirror_exit_common (job=0x55b7b4419000) at ../block/mirror.c:696
#9  0x000055b7b1577015 in mirror_prepare (job=0x55b7b4419000) at ../block/mirror.c:807
#10 0x000055b7b153a1a7 in job_prepare_locked (job=0x55b7b4419000) at ../job.c:988
#11 0x000055b7b153a0d9 in job_txn_apply_locked (job=0x55b7b4419000, fn=0x55b7b153a110 <job_prepare_locked>) at ../job.c:191
#12 0x000055b7b1538b6d in job_do_finalize_locked (job=0x55b7b4419000) at ../job.c:1011
#13 0x000055b7b153a886 in job_completed_txn_success_locked (job=0x55b7b4419000) at ../job.c:1068
#14 0x000055b7b1539372 in job_completed_locked (job=0x55b7b4419000) at ../job.c:1082
#15 0x000055b7b153a71b in job_exit (opaque=0x55b7b4419000) at ../job.c:1103
#16 0x000055b7b1726f1c in aio_bh_call (bh=0x7f8110005470) at ../util/async.c:169
#17 0x000055b7b17270ee in aio_bh_poll (ctx=0x55b7b3269210) at ../util/async.c:216
#18 0x000055b7b1702c05 in aio_dispatch (ctx=0x55b7b3269210) at ../util/aio-posix.c:423
#19 0x000055b7b1728a14 in aio_ctx_dispatch (source=0x55b7b3269210, callback=0x0, user_data=0x0) at ../util/async.c:358
#20 0x00007f8126c31c7f in g_main_dispatch (context=0x55b7b3269720) at ../glib/gmain.c:3454
#21 g_main_context_dispatch (context=0x55b7b3269720) at ../glib/gmain.c:4172
#22 0x000055b7b1729c98 in glib_pollfds_poll () at ../util/main-loop.c:290
#23 0x000055b7b1729572 in os_host_main_loop_wait (timeout=27462700) at ../util/main-loop.c:313
#24 0x000055b7b1729452 in main_loop_wait (nonblocking=0) at ../util/main-loop.c:592
#25 0x000055b7b119a1eb in qemu_main_loop () at ../softmmu/runstate.c:772
#26 0x000055b7b14c102d in qemu_default_main () at ../softmmu/main.c:37
#27 0x000055b7b14c1068 in main (argc=44, argv=0x7ffc90b05d58) at ../softmmu/main.c:48

At first I thought we just need to look into the AioContext locking in
job completion and drop it in the right places.

But in fact, first of all, blk_remove_bs() needs to make up its mind if
it wants the caller to hold the AioContext or not and document that.
Because it calls both bdrv_drained_begin() (which requires holding the
AioContext lock) and bdrv_graph_wrlock(NULL) (which forbids it).

If we could fully get rid of the AioContext lock (as we originally
stated as a goal), that would automatically solve this kind of
deadlocks.

Kevin

Re: [PULL 00/28] Block layer patches

[Stefan Hajnoczi]

On Tue, 19 Sept 2023 at 06:26, Kevin Wolf <kwolf@redhat.com> wrote:
>
> Am 18.09.2023 um 20:56 hat Stefan Hajnoczi geschrieben:
> > Hi Kevin,
> > I believe that my own commit "block-coroutine-wrapper: use
> > qemu_get_current_aio_context()" breaks this test. The failure is
> > non-deterministic (happens about 1 out of 4 runs).
> >
> > It seems the job hangs and the test times out in vm.run_job('job1', wait=5.0).
> >
> > I haven't debugged it yet but wanted to share this information to save
> > some time. Tomorrow I'll investigate further.
>
> Yes, it's relatively easily reproducible if I run the test in a loop,
> and I can't seem to reproduce it without the last patch. Should I
> unstage the full series again, or do you think that the last patch is
> really optional this time?

Please drop the last patch. I'm not aware of dependencies on the last patch.

> However, I'm unsure how the stack traces I'm seeing are related to your
> patch. Maybe it just made an existing bug more likely to be triggered?

I'll share my thoughts once I've looked at the crash today.

Regarding AioContext lock removal: I'll work on that and see what
still depends on the lock.

Stefan

> What I'm seeing is that the reader lock is held by an iothread that is
> waiting for its AioContext lock to make progress:
>
> Thread 3 (Thread 0x7f811e9346c0 (LWP 26390) "qemu-system-x86"):
> #0  0x00007f81250aaf80 in __lll_lock_wait () at /lib64/libc.so.6
> #1  0x00007f81250b149a in pthread_mutex_lock@@GLIBC_2.2.5 () at /lib64/libc.so.6
> #2  0x000055b7b170967e in qemu_mutex_lock_impl (mutex=0x55b7b34e3080, file=0x55b7b199e1f7 "../util/async.c", line=728) at ../util/qemu-thread-posix.c:94
> #3  0x000055b7b1709953 in qemu_rec_mutex_lock_impl (mutex=0x55b7b34e3080, file=0x55b7b199e1f7 "../util/async.c", line=728) at ../util/qemu-thread-posix.c:149
> #4  0x000055b7b1728318 in aio_context_acquire (ctx=0x55b7b34e3020) at ../util/async.c:728
> #5  0x000055b7b1727c49 in co_schedule_bh_cb (opaque=0x55b7b34e3020) at ../util/async.c:565
> #6  0x000055b7b1726f1c in aio_bh_call (bh=0x55b7b34e2e70) at ../util/async.c:169
> #7  0x000055b7b17270ee in aio_bh_poll (ctx=0x55b7b34e3020) at ../util/async.c:216
> #8  0x000055b7b170351d in aio_poll (ctx=0x55b7b34e3020, blocking=true) at ../util/aio-posix.c:722
> #9  0x000055b7b1518604 in iothread_run (opaque=0x55b7b2904460) at ../iothread.c:63
> #10 0x000055b7b170a955 in qemu_thread_start (args=0x55b7b34e36b0) at ../util/qemu-thread-posix.c:541
> #11 0x00007f81250ae15d in start_thread () at /lib64/libc.so.6
> #12 0x00007f812512fc00 in clone3 () at /lib64/libc.so.6
>
> On the other hand, the main thread wants to acquire the writer lock,
> but it holds the AioContext lock of the iothread (it takes it in
> job_prepare_locked()):
>
> Thread 1 (Thread 0x7f811f4b7b00 (LWP 26388) "qemu-system-x86"):
> #0  0x00007f8125122356 in ppoll () at /lib64/libc.so.6
> #1  0x000055b7b172eae0 in qemu_poll_ns (fds=0x55b7b34ec910, nfds=1, timeout=-1) at ../util/qemu-timer.c:339
> #2  0x000055b7b1704ebd in fdmon_poll_wait (ctx=0x55b7b3269210, ready_list=0x7ffc90b05680, timeout=-1) at ../util/fdmon-poll.c:79
> #3  0x000055b7b1703284 in aio_poll (ctx=0x55b7b3269210, blocking=true) at ../util/aio-posix.c:670
> #4  0x000055b7b1567c3b in bdrv_graph_wrlock (bs=0x0) at ../block/graph-lock.c:145
> #5  0x000055b7b1554c1c in blk_remove_bs (blk=0x55b7b4425800) at ../block/block-backend.c:916
> #6  0x000055b7b1554779 in blk_delete (blk=0x55b7b4425800) at ../block/block-backend.c:497
> #7  0x000055b7b1554133 in blk_unref (blk=0x55b7b4425800) at ../block/block-backend.c:557
> #8  0x000055b7b157a149 in mirror_exit_common (job=0x55b7b4419000) at ../block/mirror.c:696
> #9  0x000055b7b1577015 in mirror_prepare (job=0x55b7b4419000) at ../block/mirror.c:807
> #10 0x000055b7b153a1a7 in job_prepare_locked (job=0x55b7b4419000) at ../job.c:988
> #11 0x000055b7b153a0d9 in job_txn_apply_locked (job=0x55b7b4419000, fn=0x55b7b153a110 <job_prepare_locked>) at ../job.c:191
> #12 0x000055b7b1538b6d in job_do_finalize_locked (job=0x55b7b4419000) at ../job.c:1011
> #13 0x000055b7b153a886 in job_completed_txn_success_locked (job=0x55b7b4419000) at ../job.c:1068
> #14 0x000055b7b1539372 in job_completed_locked (job=0x55b7b4419000) at ../job.c:1082
> #15 0x000055b7b153a71b in job_exit (opaque=0x55b7b4419000) at ../job.c:1103
> #16 0x000055b7b1726f1c in aio_bh_call (bh=0x7f8110005470) at ../util/async.c:169
> #17 0x000055b7b17270ee in aio_bh_poll (ctx=0x55b7b3269210) at ../util/async.c:216
> #18 0x000055b7b1702c05 in aio_dispatch (ctx=0x55b7b3269210) at ../util/aio-posix.c:423
> #19 0x000055b7b1728a14 in aio_ctx_dispatch (source=0x55b7b3269210, callback=0x0, user_data=0x0) at ../util/async.c:358
> #20 0x00007f8126c31c7f in g_main_dispatch (context=0x55b7b3269720) at ../glib/gmain.c:3454
> #21 g_main_context_dispatch (context=0x55b7b3269720) at ../glib/gmain.c:4172
> #22 0x000055b7b1729c98 in glib_pollfds_poll () at ../util/main-loop.c:290
> #23 0x000055b7b1729572 in os_host_main_loop_wait (timeout=27462700) at ../util/main-loop.c:313
> #24 0x000055b7b1729452 in main_loop_wait (nonblocking=0) at ../util/main-loop.c:592
> #25 0x000055b7b119a1eb in qemu_main_loop () at ../softmmu/runstate.c:772
> #26 0x000055b7b14c102d in qemu_default_main () at ../softmmu/main.c:37
> #27 0x000055b7b14c1068 in main (argc=44, argv=0x7ffc90b05d58) at ../softmmu/main.c:48
>
> At first I thought we just need to look into the AioContext locking in
> job completion and drop it in the right places.
>
> But in fact, first of all, blk_remove_bs() needs to make up its mind if
> it wants the caller to hold the AioContext or not and document that.
> Because it calls both bdrv_drained_begin() (which requires holding the
> AioContext lock) and bdrv_graph_wrlock(NULL) (which forbids it).
>
> If we could fully get rid of the AioContext lock (as we originally
> stated as a goal), that would automatically solve this kind of
> deadlocks.
>
> Kevin
>

Re: [PULL 00/28] Block layer patches

[Stefan Hajnoczi]

On Tue, 19 Sept 2023 at 06:26, Kevin Wolf <kwolf@redhat.com> wrote:
>
> Am 18.09.2023 um 20:56 hat Stefan Hajnoczi geschrieben:
> > Hi Kevin,
> > I believe that my own commit "block-coroutine-wrapper: use
> > qemu_get_current_aio_context()" breaks this test. The failure is
> > non-deterministic (happens about 1 out of 4 runs).
> >
> > It seems the job hangs and the test times out in vm.run_job('job1', wait=5.0).
> >
> > I haven't debugged it yet but wanted to share this information to save
> > some time. Tomorrow I'll investigate further.
>
> Yes, it's relatively easily reproducible if I run the test in a loop,
> and I can't seem to reproduce it without the last patch. Should I
> unstage the full series again, or do you think that the last patch is
> really optional this time?
>
> However, I'm unsure how the stack traces I'm seeing are related to your
> patch. Maybe it just made an existing bug more likely to be triggered?
>
> What I'm seeing is that the reader lock is held by an iothread that is
> waiting for its AioContext lock to make progress:
>
> Thread 3 (Thread 0x7f811e9346c0 (LWP 26390) "qemu-system-x86"):
> #0  0x00007f81250aaf80 in __lll_lock_wait () at /lib64/libc.so.6
> #1  0x00007f81250b149a in pthread_mutex_lock@@GLIBC_2.2.5 () at /lib64/libc.so.6
> #2  0x000055b7b170967e in qemu_mutex_lock_impl (mutex=0x55b7b34e3080, file=0x55b7b199e1f7 "../util/async.c", line=728) at ../util/qemu-thread-posix.c:94
> #3  0x000055b7b1709953 in qemu_rec_mutex_lock_impl (mutex=0x55b7b34e3080, file=0x55b7b199e1f7 "../util/async.c", line=728) at ../util/qemu-thread-posix.c:149
> #4  0x000055b7b1728318 in aio_context_acquire (ctx=0x55b7b34e3020) at ../util/async.c:728
> #5  0x000055b7b1727c49 in co_schedule_bh_cb (opaque=0x55b7b34e3020) at ../util/async.c:565
> #6  0x000055b7b1726f1c in aio_bh_call (bh=0x55b7b34e2e70) at ../util/async.c:169
> #7  0x000055b7b17270ee in aio_bh_poll (ctx=0x55b7b34e3020) at ../util/async.c:216
> #8  0x000055b7b170351d in aio_poll (ctx=0x55b7b34e3020, blocking=true) at ../util/aio-posix.c:722
> #9  0x000055b7b1518604 in iothread_run (opaque=0x55b7b2904460) at ../iothread.c:63
> #10 0x000055b7b170a955 in qemu_thread_start (args=0x55b7b34e36b0) at ../util/qemu-thread-posix.c:541
> #11 0x00007f81250ae15d in start_thread () at /lib64/libc.so.6
> #12 0x00007f812512fc00 in clone3 () at /lib64/libc.so.6
>
> On the other hand, the main thread wants to acquire the writer lock,
> but it holds the AioContext lock of the iothread (it takes it in
> job_prepare_locked()):
>
> Thread 1 (Thread 0x7f811f4b7b00 (LWP 26388) "qemu-system-x86"):
> #0  0x00007f8125122356 in ppoll () at /lib64/libc.so.6
> #1  0x000055b7b172eae0 in qemu_poll_ns (fds=0x55b7b34ec910, nfds=1, timeout=-1) at ../util/qemu-timer.c:339
> #2  0x000055b7b1704ebd in fdmon_poll_wait (ctx=0x55b7b3269210, ready_list=0x7ffc90b05680, timeout=-1) at ../util/fdmon-poll.c:79
> #3  0x000055b7b1703284 in aio_poll (ctx=0x55b7b3269210, blocking=true) at ../util/aio-posix.c:670
> #4  0x000055b7b1567c3b in bdrv_graph_wrlock (bs=0x0) at ../block/graph-lock.c:145
> #5  0x000055b7b1554c1c in blk_remove_bs (blk=0x55b7b4425800) at ../block/block-backend.c:916
> #6  0x000055b7b1554779 in blk_delete (blk=0x55b7b4425800) at ../block/block-backend.c:497
> #7  0x000055b7b1554133 in blk_unref (blk=0x55b7b4425800) at ../block/block-backend.c:557
> #8  0x000055b7b157a149 in mirror_exit_common (job=0x55b7b4419000) at ../block/mirror.c:696
> #9  0x000055b7b1577015 in mirror_prepare (job=0x55b7b4419000) at ../block/mirror.c:807
> #10 0x000055b7b153a1a7 in job_prepare_locked (job=0x55b7b4419000) at ../job.c:988
> #11 0x000055b7b153a0d9 in job_txn_apply_locked (job=0x55b7b4419000, fn=0x55b7b153a110 <job_prepare_locked>) at ../job.c:191
> #12 0x000055b7b1538b6d in job_do_finalize_locked (job=0x55b7b4419000) at ../job.c:1011
> #13 0x000055b7b153a886 in job_completed_txn_success_locked (job=0x55b7b4419000) at ../job.c:1068
> #14 0x000055b7b1539372 in job_completed_locked (job=0x55b7b4419000) at ../job.c:1082
> #15 0x000055b7b153a71b in job_exit (opaque=0x55b7b4419000) at ../job.c:1103
> #16 0x000055b7b1726f1c in aio_bh_call (bh=0x7f8110005470) at ../util/async.c:169
> #17 0x000055b7b17270ee in aio_bh_poll (ctx=0x55b7b3269210) at ../util/async.c:216
> #18 0x000055b7b1702c05 in aio_dispatch (ctx=0x55b7b3269210) at ../util/aio-posix.c:423
> #19 0x000055b7b1728a14 in aio_ctx_dispatch (source=0x55b7b3269210, callback=0x0, user_data=0x0) at ../util/async.c:358
> #20 0x00007f8126c31c7f in g_main_dispatch (context=0x55b7b3269720) at ../glib/gmain.c:3454
> #21 g_main_context_dispatch (context=0x55b7b3269720) at ../glib/gmain.c:4172
> #22 0x000055b7b1729c98 in glib_pollfds_poll () at ../util/main-loop.c:290
> #23 0x000055b7b1729572 in os_host_main_loop_wait (timeout=27462700) at ../util/main-loop.c:313
> #24 0x000055b7b1729452 in main_loop_wait (nonblocking=0) at ../util/main-loop.c:592
> #25 0x000055b7b119a1eb in qemu_main_loop () at ../softmmu/runstate.c:772
> #26 0x000055b7b14c102d in qemu_default_main () at ../softmmu/main.c:37
> #27 0x000055b7b14c1068 in main (argc=44, argv=0x7ffc90b05d58) at ../softmmu/main.c:48
>
> At first I thought we just need to look into the AioContext locking in
> job completion and drop it in the right places.
>
> But in fact, first of all, blk_remove_bs() needs to make up its mind if
> it wants the caller to hold the AioContext or not and document that.
> Because it calls both bdrv_drained_begin() (which requires holding the
> AioContext lock) and bdrv_graph_wrlock(NULL) (which forbids it).

I was surprised to see bdrv_graph_wrlock(NULL) called. The AioContext
lock is held across aio_poll() and that's why the hang occurs.

I'll make blk_remove_bs() consistent with respect to the AioContext
lock so this test failure can be fixed.

> If we could fully get rid of the AioContext lock (as we originally
> stated as a goal), that would automatically solve this kind of
> deadlocks.

Although it's not an indication that it's already safe to remove the
AioContext lock, I commented out the lock/unlock in
aio_context_acquire/release() and found that "make check" passes. Only
graph-changes-while-io fails when I run "qemu-iotests -qcow2".

I think the main thing keeping the AioContext lock around is
AIO_WAIT_WHILE(). The caller must hold the lock and that forces many
APIs to extend this requirement to their caller.

Perhaps more AIO_WAIT_WHILE() instances can now be converted to
AIO_WAIT_WHILE_UNLOCKED().

Stefan

Re: [PULL 00/28] Block layer patches

[Stefan Hajnoczi]

On Tue, 19 Sept 2023 at 06:26, Kevin Wolf <kwolf@redhat.com> wrote:
> Am 18.09.2023 um 20:56 hat Stefan Hajnoczi geschrieben:
> If we could fully get rid of the AioContext lock (as we originally
> stated as a goal), that would automatically solve this kind of
> deadlocks.

Grepping for "ctx locked", "context acquired", etc does not bring up a
lot of comments describing variables that are protected by the
AioContext lock.

However, there are at least hundreds of functions that assume they are
called with the AioContext lock held.

There are a few strategies:

Top-down
--------
Shorten AioContext lock critical sections to cover only APIs that need them.
Then push the lock down into the API and repeat the next lower level until
aio_context_acquire() + AIO_WAIT_WHILE() + aio_context_release() can be
replaced with AIO_WAIT_UNLOCKED().

Bottom-up
---------
Switch AIO_WAIT_WHILE() to aio_context_release() + AIO_WAIT_WHILE_UNLOCKED() +
aio_context_acquire(). Then move the lock up into callers and repeat at the
next higher level until aio_context_acquire() + aio_context_release() cancel
each other out.

Big bang
--------
Remove aio_context_acquire/release() and fix tests until they pass.

I think top-down is safer than bottom-up, because bottom-up is more
likely to cause issues with callers that do not tolerate temporarily
dropping the lock.

The big bang approach is only reasonable if the AioContext lock is no
longer used to protect variables (which we don't know for sure because
that requires auditing every line of code).

My concern with the top-down approach is that so much code needs to be
audited and the conversions are temporary steps (it's almost a waste
of time for maintainers to review them).

I'm tempted to go for the big bang approach but also don't want to
introduce a slew of new race conditions. :/

Stefan