[Qemu-devel] [PATCH v4 00/25] block: Fix some filename generation issues

[Qemu-devel] [PATCH v4 00/25] block: Fix some filename generation issues

[Max Reitz]

[If you have read the cover letter in v2 or v3, there is nothing new
 here; feel free to skip to the bottom to read the changes from v3.]

There are some issues regarding filename generation right now:

- You always get a JSON filename if you set even a single qcow2-specific
  runtime options (as long as it does not have a dot in it, which is a
  bug, too, but here it is working in our favor...). That is not nice
  and actually breaks the usage of backing files with relative
  filenames with such qcow2 BDS.

- As hinted above, you cannot use relative backing filenames with BDS
  that have a JSON filename only, even though qemu might be able to
  obtain the directory name by walking through the BDS graph to the
  protocol level.

- Overriding the backing file at runtime should invalidate the filename
  because it actually changes the BDS's data.  Therefore, we need to
  force a JSON filename in that case, containing the backing file
  override.

- Much of our code assumes paths never to exceed PATH_MAX in length.
  This is wrong, at least because of JSON filenames. This should be
  fixed wherever the opportunity arises.

- If a driver decides to implement bdrv_refresh_filename(), that
  implementation has to not only refresh the filename (as one would
  think) but it must also refresh the runtime options
  (bs->full_open_options). That is stupid. (I'm allowed to say that
  because I'm to blame for it.)

This series is enclosed by four patches (two at the front, two at the
back) that fix more or less general issues. They are included because:
- Patch 1 is required so that in patch 3 it's obvious why we don't need
  to set backing_overriden there or call bdrv_refresh_filename()
- Patch 2 is already reviewed, so I might just as well keep it.
- Patches 24 and 25 are basically general bug fixes. Their connection to
  this series is obvious, however, I think, and they depend on the rest
  of the series, so I decided to just put them in.

Patches 3 and 4 address the third issue above, and patch 23 adds
something that's missing from patch 3. It cannot be squashed into patch
3, however, because it depends on functionality introduced by patches 18
to 22.
Consequently, patch 3 introduces a FIXME that is resolved by patch 23.

Patches 5 to 9 address the fourth issue above, and are also necessary
preparation for the following patches.

Patches 10 to 16 address the second issue above, patch 17 adds a test
case. They implement a bdrv_dirname() function that returns the base
directory of a BDS by walking through the BDS graph to the protocol
layer and then trying to obtain a path based on that BDS's
exact_filename. This obviously fails if exact_filename on the protocol
layer is not set.
This behavior can be overriden either by any block driver along the way
implementing bdrv_dirname() itself or by the user through the new
'base-directory' node option. This may allow us to resolve relative
filenames even if the reference BDS only has a JSON filename.

Patches 18 to 22 address both the first and last issues above. They add
a field called "sgfnt_runtime_opts" to the BlockDriver structure. Block
drivers may point this to an array containing all of the runtime options
they accept that may change their BDS's data (i.e. that are
"significant"). bdrv_refresh_filename() will use this list to generate
bs->full_open_options itself (with only a little help by the block
driver, if necessary, through the .bdrv_gather_child_options()
function). This not only simplifies the process significantly, but also
results in the default implementation generating JSON filenames only
when really necessary.


v4:
- Replaced the superfluous explicit setting of backing_filename to NULL
  in patch 7 by a comment [Berto]
- Fixed the protocol BDS test in patch 22


git-backport-diff against v3:

Key:
[----] : patches are identical
[####] : number of functional differences between upstream/downstream patch
[down] : patch is downstream-only
The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively

001/25:[----] [--] 'block/mirror: Small absolute-paths simplification'
002/25:[----] [--] 'block: Use children list in bdrv_refresh_filename'
003/25:[----] [--] 'block: Add BDS.backing_overridden'
004/25:[----] [--] 'block: Respect backing bs in bdrv_refresh_filename'
005/25:[----] [--] 'block: Make path_combine() return the path'
006/25:[----] [--] 'block: bdrv_get_full_backing_filename_from_...'s ret. val.'
007/25:[0002] [FC] 'block: bdrv_get_full_backing_filename's ret. val.'
008/25:[----] [--] 'block: Add bdrv_make_absolute_filename()'
009/25:[----] [--] 'block: Fix bdrv_find_backing_image()'
010/25:[----] [--] 'block: Add bdrv_dirname()'
011/25:[----] [-C] 'blkverify: Make bdrv_dirname() return NULL'
012/25:[----] [--] 'quorum: Make bdrv_dirname() return NULL'
013/25:[----] [--] 'block/nbd: Implement bdrv_dirname()'
014/25:[----] [--] 'block/nfs: Implement bdrv_dirname()'
015/25:[----] [--] 'block: Use bdrv_dirname() for relative filenames'
016/25:[----] [--] 'block: Add 'base-directory' BDS option'
017/25:[----] [--] 'iotests: Add quorum case to test 110'
018/25:[----] [--] 'block: Add sgfnt_runtime_opts to BlockDriver'
019/25:[----] [--] 'block: Add BlockDriver.bdrv_gather_child_options'
020/25:[----] [--] 'block: Generically refresh runtime options'
021/25:[----] [--] 'block: Purify .bdrv_refresh_filename()'
022/25:[0002] [FC] 'block: Do not copy exact_filename from format file'
023/25:[----] [-C] 'block: Fix FIXME from "Add BDS.backing_overridden"'
024/25:[----] [--] 'block/curl: Implement bdrv_refresh_filename()'
025/25:[----] [--] 'block/null: Generate filename even with latency-ns'



Max Reitz (25):
  block/mirror: Small absolute-paths simplification
  block: Use children list in bdrv_refresh_filename
  block: Add BDS.backing_overridden
  block: Respect backing bs in bdrv_refresh_filename
  block: Make path_combine() return the path
  block: bdrv_get_full_backing_filename_from_...'s ret. val.
  block: bdrv_get_full_backing_filename's ret. val.
  block: Add bdrv_make_absolute_filename()
  block: Fix bdrv_find_backing_image()
  block: Add bdrv_dirname()
  blkverify: Make bdrv_dirname() return NULL
  quorum: Make bdrv_dirname() return NULL
  block/nbd: Implement bdrv_dirname()
  block/nfs: Implement bdrv_dirname()
  block: Use bdrv_dirname() for relative filenames
  block: Add 'base-directory' BDS option
  iotests: Add quorum case to test 110
  block: Add sgfnt_runtime_opts to BlockDriver
  block: Add BlockDriver.bdrv_gather_child_options
  block: Generically refresh runtime options
  block: Purify .bdrv_refresh_filename()
  block: Do not copy exact_filename from format file
  block: Fix FIXME from "Add BDS.backing_overridden"
  block/curl: Implement bdrv_refresh_filename()
  block/null: Generate filename even with latency-ns

 qapi/block-core.json          |   9 +
 include/block/block.h         |  15 +-
 include/block/block_int.h     |  14 +-
 block.c                       | 491 ++++++++++++++++++++++++++++--------------
 block/blkdebug.c              |  50 ++---
 block/blkverify.c             |  30 +--
 block/curl.c                  |  38 ++++
 block/gluster.c               |  19 ++
 block/mirror.c                |  10 +-
 block/nbd.c                   |  54 +++--
 block/nfs.c                   |  50 ++---
 block/null.c                  |  33 ++-
 block/qapi.c                  |  12 +-
 block/quorum.c                |  62 +++---
 block/rbd.c                   |   2 +
 block/vmdk.c                  |  24 ++-
 block/vvfat.c                 |   4 +
 blockdev.c                    |  16 ++
 tests/qemu-iotests/051.out    |   8 +-
 tests/qemu-iotests/051.pc.out |   8 +-
 tests/qemu-iotests/110        |  51 ++++-
 tests/qemu-iotests/110.out    |  14 +-
 22 files changed, 678 insertions(+), 336 deletions(-)

-- 
2.11.0

[Qemu-devel] [PATCH v4 01/25] block/mirror: Small absolute-paths simplification

[Max Reitz]

When invoking drive-mirror in absolute-paths mode, the target's backing
BDS is assigned to it in mirror_complete(). The current logic only does
so if the target does not have that backing BDS already; but it actually
cannot have a backing BDS at all (the BDS is opened with O_NO_BACKING in
qmp_drive_mirror()), so just assert that and assign the new backing BDS
unconditionally.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 block/mirror.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c
index 301ba9219a..4ece624549 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -888,9 +888,9 @@ static void mirror_complete(BlockJob *job, Error **errp)
 
     if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {
         BlockDriverState *backing = s->is_none_mode ? src : s->base;
-        if (backing_bs(target) != backing) {
-            bdrv_set_backing_hd(target, backing);
-        }
+
+        assert(!target->backing);
+        bdrv_set_backing_hd(target, backing);
     }
 
     s->should_complete = true;
-- 
2.11.0

[Qemu-devel] [PATCH v4 02/25] block: Use children list in bdrv_refresh_filename

[Max Reitz]

bdrv_refresh_filename() should invoke itself recursively on all
children, not just on file.

With that change, we can remove the manual invocations in blkverify and
quorum.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 block.c           | 9 +++++----
 block/blkverify.c | 3 ---
 block/quorum.c    | 1 -
 3 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/block.c b/block.c
index 39ddea3411..1615f5da1f 100644
--- a/block.c
+++ b/block.c
@@ -3948,16 +3948,17 @@ static bool append_open_options(QDict *d, BlockDriverState *bs)
 void bdrv_refresh_filename(BlockDriverState *bs)
 {
     BlockDriver *drv = bs->drv;
+    BdrvChild *child;
     QDict *opts;
 
     if (!drv) {
         return;
     }
 
-    /* This BDS's file name will most probably depend on its file's name, so
-     * refresh that first */
-    if (bs->file) {
-        bdrv_refresh_filename(bs->file->bs);
+    /* This BDS's file name may depend on any of its children's file names, so
+     * refresh those first */
+    QLIST_FOREACH(child, &bs->children, next) {
+        bdrv_refresh_filename(child->bs);
     }
 
     if (drv->bdrv_refresh_filename) {
diff --git a/block/blkverify.c b/block/blkverify.c
index 43a940c2f5..38a8c68029 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -284,9 +284,6 @@ static void blkverify_refresh_filename(BlockDriverState *bs, QDict *options)
 {
     BDRVBlkverifyState *s = bs->opaque;
 
-    /* bs->file->bs has already been refreshed */
-    bdrv_refresh_filename(s->test_file->bs);
-
     if (bs->file->bs->full_open_options
         && s->test_file->bs->full_open_options)
     {
diff --git a/block/quorum.c b/block/quorum.c
index 86e2072dce..112370eea2 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1080,7 +1080,6 @@ static void quorum_refresh_filename(BlockDriverState *bs, QDict *options)
     int i;
 
     for (i = 0; i < s->num_children; i++) {
-        bdrv_refresh_filename(s->children[i]->bs);
         if (!s->children[i]->bs->full_open_options) {
             return;
         }
-- 
2.11.0

[Qemu-devel] [PATCH v4 03/25] block: Add BDS.backing_overridden

[Max Reitz]

If the backing file is overridden, this most probably does change the
guest-visible data of a BDS. Therefore, we will need to consider this in
bdrv_refresh_filename().

Adding a new field to the BDS is not nice, but it is very simple and
exactly keeps track of whether the backing file has been overridden.

This commit adds a FIXME which will be remedied by a follow-up commit.
Until then, the respective piece of code will not result in any behavior
that is worse than what we currently have.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 include/block/block_int.h |  1 +
 block.c                   | 13 +++++++++++++
 block/mirror.c            |  4 ++++
 blockdev.c                | 16 ++++++++++++++++
 4 files changed, 34 insertions(+)

diff --git a/include/block/block_int.h b/include/block/block_int.h
index 4e4562d444..c1f057ab47 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -461,6 +461,7 @@ struct BlockDriverState {
     char backing_file[PATH_MAX]; /* if non zero, the image is a diff of
                                     this file image */
     char backing_format[16]; /* if non-zero and backing_file exists */
+    bool backing_overridden; /* backing file has been specified by the user */
 
     QDict *full_open_options;
     char exact_filename[PATH_MAX];
diff --git a/block.c b/block.c
index 1615f5da1f..438201d949 100644
--- a/block.c
+++ b/block.c
@@ -1495,6 +1495,11 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
     reference = qdict_get_try_str(parent_options, bdref_key);
     if (reference || qdict_haskey(options, "file.filename")) {
         backing_filename[0] = '\0';
+
+        /* FIXME: Should also be set to true if @options contains other runtime
+         *        options which control the data that is read from the backing
+         *        BDS */
+        bs->backing_overridden = true;
     } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
         QDECREF(options);
         goto free_exit;
@@ -1659,6 +1664,9 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
     bdrv_ref(bs_snapshot);
     bdrv_append(bs_snapshot, bs);
 
+    bs_snapshot->backing_overridden = true;
+    bdrv_refresh_filename(bs_snapshot);
+
     g_free(tmp_filename);
     return bs_snapshot;
 
@@ -1786,6 +1794,7 @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
     backing = qdict_get_try_str(options, "backing");
     if (backing && *backing == '\0') {
         flags |= BDRV_O_NO_BACKING;
+        bs->backing_overridden = true;
         qdict_del(options, "backing");
     }
 
@@ -3959,6 +3968,10 @@ void bdrv_refresh_filename(BlockDriverState *bs)
      * refresh those first */
     QLIST_FOREACH(child, &bs->children, next) {
         bdrv_refresh_filename(child->bs);
+
+        if (child->role == &child_backing && child->bs->backing_overridden) {
+            bs->backing_overridden = true;
+        }
     }
 
     if (drv->bdrv_refresh_filename) {
diff --git a/block/mirror.c b/block/mirror.c
index 4ece624549..6cb6cbd127 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -891,6 +891,10 @@ static void mirror_complete(BlockJob *job, Error **errp)
 
         assert(!target->backing);
         bdrv_set_backing_hd(target, backing);
+
+        /* The target image's file already has been created with the backing
+         * file we just set, so there is no need to set backing_overridden or
+         * call bdrv_refresh_filename(). */
     }
 
     s->should_complete = true;
diff --git a/blockdev.c b/blockdev.c
index 245e1e1d17..7889babd40 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1771,6 +1771,8 @@ static void external_snapshot_commit(BlkActionState *common)
 {
     ExternalSnapshotState *state =
                              DO_UPCAST(ExternalSnapshotState, common, common);
+    TransactionAction *action = common->action;
+    bool image_was_existing = false;
 
     bdrv_set_aio_context(state->new_bs, state->aio_context);
 
@@ -1783,6 +1785,20 @@ static void external_snapshot_commit(BlkActionState *common)
         bdrv_reopen(state->old_bs, state->old_bs->open_flags & ~BDRV_O_RDWR,
                     NULL);
     }
+
+    if (action->type == TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC) {
+        BlockdevSnapshotSync *s = action->u.blockdev_snapshot_sync.data;
+        if (s->has_mode && s->mode == NEW_IMAGE_MODE_EXISTING) {
+            image_was_existing = true;
+        }
+    } else {
+        image_was_existing = true;
+    }
+
+    if (image_was_existing) {
+        state->new_bs->backing_overridden = true;
+        bdrv_refresh_filename(state->new_bs);
+    }
 }
 
 static void external_snapshot_abort(BlkActionState *common)
-- 
2.11.0

[Qemu-devel] [PATCH v4 04/25] block: Respect backing bs in bdrv_refresh_filename

[Max Reitz]

Basically, bdrv_refresh_filename() should respect all children of a
BlockDriverState. However, generally those children are driver-specific,
so this function cannot handle the general case. On the other hand,
there are only few drivers which use other children than @file and
@backing (that being vmdk, quorum, and blkverify).

Most block drivers only use @file and/or @backing (if they use any
children at all). Both can be implemented directly in
bdrv_refresh_filename.

The user overriding the file's filename is already handled, however, the
user overriding the backing file is not. If this is done, opening the
BDS with the plain filename of its file will not be correct, so we may
not set bs->exact_filename in that case.

iotest 051 contains test cases for overwriting the backing file, and so
its output changes with this patch applied (which I consider a good
thing).

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c                       | 12 +++++++++++-
 tests/qemu-iotests/051.out    |  8 ++++----
 tests/qemu-iotests/051.pc.out |  8 ++++----
 3 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/block.c b/block.c
index 438201d949..f7a287a60d 100644
--- a/block.c
+++ b/block.c
@@ -3999,6 +3999,7 @@ void bdrv_refresh_filename(BlockDriverState *bs)
 
         opts = qdict_new();
         has_open_options = append_open_options(opts, bs);
+        has_open_options |= bs->backing_overridden;
 
         /* If no specific options have been given for this BDS, the filename of
          * the underlying file should suffice for this one as well */
@@ -4010,13 +4011,22 @@ void bdrv_refresh_filename(BlockDriverState *bs)
          * file BDS. The full options QDict of that file BDS should somehow
          * contain a representation of the filename, therefore the following
          * suffices without querying the (exact_)filename of this BDS. */
-        if (bs->file->bs->full_open_options) {
+        if (bs->file->bs->full_open_options &&
+            (!bs->backing || bs->backing->bs->full_open_options))
+        {
             qdict_put_obj(opts, "driver",
                           QOBJECT(qstring_from_str(drv->format_name)));
             QINCREF(bs->file->bs->full_open_options);
             qdict_put_obj(opts, "file",
                           QOBJECT(bs->file->bs->full_open_options));
 
+            if (bs->backing) {
+                QINCREF(bs->backing->bs->full_open_options);
+                qdict_put(opts, "backing", bs->backing->bs->full_open_options);
+            } else if (bs->backing_overridden && !bs->backing) {
+                qdict_put(opts, "backing", qstring_new());
+            }
+
             bs->full_open_options = opts;
         } else {
             QDECREF(opts);
diff --git a/tests/qemu-iotests/051.out b/tests/qemu-iotests/051.out
index 42bf4164ca..0d0b3b138c 100644
--- a/tests/qemu-iotests/051.out
+++ b/tests/qemu-iotests/051.out
@@ -59,7 +59,7 @@ QEMU X.Y.Z monitor - type 'help' for more information
 Testing: -drive file=TEST_DIR/t.qcow2,driver=qcow2,backing.file.filename=TEST_DIR/t.qcow2.orig,if=none,id=drive0 -nodefaults
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) i^[[K^[[Din^[[K^[[D^[[Dinf^[[K^[[D^[[D^[[Dinfo^[[K^[[D^[[D^[[D^[[Dinfo ^[[K^[[D^[[D^[[D^[[D^[[Dinfo b^[[K^[[D^[[D^[[D^[[D^[[D^[[Dinfo bl^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo blo^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo bloc^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo block^[[K
-drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
+drive0 (NODE_NAME): json:{"backing": {"driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2.orig"}}, "driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2"}} (qcow2)
     Removable device: not locked, tray closed
     Cache mode:       writeback
     Backing file:     TEST_DIR/t.qcow2.orig (chain depth: 1)
@@ -148,7 +148,7 @@ QEMU_PROG: -drive driver=null-co,cache=invalid_value: invalid cache option
 Testing: -drive file=TEST_DIR/t.qcow2,cache=writeback,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) i^[[K^[[Din^[[K^[[D^[[Dinf^[[K^[[D^[[D^[[Dinfo^[[K^[[D^[[D^[[D^[[Dinfo ^[[K^[[D^[[D^[[D^[[D^[[Dinfo b^[[K^[[D^[[D^[[D^[[D^[[D^[[Dinfo bl^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo blo^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo bloc^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo block^[[K
-drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
+drive0 (NODE_NAME): json:{"backing": {"driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2.base"}}, "driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2"}} (qcow2)
     Removable device: not locked, tray closed
     Cache mode:       writeback
     Backing file:     TEST_DIR/t.qcow2.base (chain depth: 1)
@@ -168,7 +168,7 @@ backing-file: TEST_DIR/t.qcow2.base (file, read-only)
 Testing: -drive file=TEST_DIR/t.qcow2,cache=writethrough,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) i^[[K^[[Din^[[K^[[D^[[Dinf^[[K^[[D^[[D^[[Dinfo^[[K^[[D^[[D^[[D^[[Dinfo ^[[K^[[D^[[D^[[D^[[D^[[Dinfo b^[[K^[[D^[[D^[[D^[[D^[[D^[[Dinfo bl^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo blo^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo bloc^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo block^[[K
-drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
+drive0 (NODE_NAME): json:{"backing": {"driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2.base"}}, "driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2"}} (qcow2)
     Removable device: not locked, tray closed
     Cache mode:       writethrough
     Backing file:     TEST_DIR/t.qcow2.base (chain depth: 1)
@@ -188,7 +188,7 @@ backing-file: TEST_DIR/t.qcow2.base (file, read-only)
 Testing: -drive file=TEST_DIR/t.qcow2,cache=unsafe,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) i^[[K^[[Din^[[K^[[D^[[Dinf^[[K^[[D^[[D^[[Dinfo^[[K^[[D^[[D^[[D^[[Dinfo ^[[K^[[D^[[D^[[D^[[D^[[Dinfo b^[[K^[[D^[[D^[[D^[[D^[[D^[[Dinfo bl^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo blo^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo bloc^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo block^[[K
-drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
+drive0 (NODE_NAME): json:{"backing": {"driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2.base"}}, "driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2"}} (qcow2)
     Removable device: not locked, tray closed
     Cache mode:       writeback, ignore flushes
     Backing file:     TEST_DIR/t.qcow2.base (chain depth: 1)
diff --git a/tests/qemu-iotests/051.pc.out b/tests/qemu-iotests/051.pc.out
index 603bb768d6..4b830bc71a 100644
--- a/tests/qemu-iotests/051.pc.out
+++ b/tests/qemu-iotests/051.pc.out
@@ -59,7 +59,7 @@ QEMU X.Y.Z monitor - type 'help' for more information
 Testing: -drive file=TEST_DIR/t.qcow2,driver=qcow2,backing.file.filename=TEST_DIR/t.qcow2.orig,if=none,id=drive0 -nodefaults
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) i^[[K^[[Din^[[K^[[D^[[Dinf^[[K^[[D^[[D^[[Dinfo^[[K^[[D^[[D^[[D^[[Dinfo ^[[K^[[D^[[D^[[D^[[D^[[Dinfo b^[[K^[[D^[[D^[[D^[[D^[[D^[[Dinfo bl^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo blo^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo bloc^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo block^[[K
-drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
+drive0 (NODE_NAME): json:{"backing": {"driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2.orig"}}, "driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2"}} (qcow2)
     Removable device: not locked, tray closed
     Cache mode:       writeback
     Backing file:     TEST_DIR/t.qcow2.orig (chain depth: 1)
@@ -242,7 +242,7 @@ QEMU_PROG: -drive driver=null-co,cache=invalid_value: invalid cache option
 Testing: -drive file=TEST_DIR/t.qcow2,cache=writeback,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) i^[[K^[[Din^[[K^[[D^[[Dinf^[[K^[[D^[[D^[[Dinfo^[[K^[[D^[[D^[[D^[[Dinfo ^[[K^[[D^[[D^[[D^[[D^[[Dinfo b^[[K^[[D^[[D^[[D^[[D^[[D^[[Dinfo bl^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo blo^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo bloc^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo block^[[K
-drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
+drive0 (NODE_NAME): json:{"backing": {"driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2.base"}}, "driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2"}} (qcow2)
     Removable device: not locked, tray closed
     Cache mode:       writeback
     Backing file:     TEST_DIR/t.qcow2.base (chain depth: 1)
@@ -262,7 +262,7 @@ backing-file: TEST_DIR/t.qcow2.base (file, read-only)
 Testing: -drive file=TEST_DIR/t.qcow2,cache=writethrough,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) i^[[K^[[Din^[[K^[[D^[[Dinf^[[K^[[D^[[D^[[Dinfo^[[K^[[D^[[D^[[D^[[Dinfo ^[[K^[[D^[[D^[[D^[[D^[[Dinfo b^[[K^[[D^[[D^[[D^[[D^[[D^[[Dinfo bl^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo blo^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo bloc^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo block^[[K
-drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
+drive0 (NODE_NAME): json:{"backing": {"driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2.base"}}, "driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2"}} (qcow2)
     Removable device: not locked, tray closed
     Cache mode:       writethrough
     Backing file:     TEST_DIR/t.qcow2.base (chain depth: 1)
@@ -282,7 +282,7 @@ backing-file: TEST_DIR/t.qcow2.base (file, read-only)
 Testing: -drive file=TEST_DIR/t.qcow2,cache=unsafe,backing.file.filename=TEST_DIR/t.qcow2.base,backing.cache.no-flush=on,backing.node-name=backing,backing.file.node-name=backing-file,file.node-name=file,if=none,id=drive0 -nodefaults
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) i^[[K^[[Din^[[K^[[D^[[Dinf^[[K^[[D^[[D^[[Dinfo^[[K^[[D^[[D^[[D^[[Dinfo ^[[K^[[D^[[D^[[D^[[D^[[Dinfo b^[[K^[[D^[[D^[[D^[[D^[[D^[[Dinfo bl^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo blo^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo bloc^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo block^[[K
-drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
+drive0 (NODE_NAME): json:{"backing": {"driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2.base"}}, "driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2"}} (qcow2)
     Removable device: not locked, tray closed
     Cache mode:       writeback, ignore flushes
     Backing file:     TEST_DIR/t.qcow2.base (chain depth: 1)
-- 
2.11.0

Re: [Qemu-devel] [PATCH v4 03/25] block: Add BDS.backing_overridden

[Eric Blake]

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On 01/11/2017 12:14 PM, Max Reitz wrote:
> If the backing file is overridden, this most probably does change the
> guest-visible data of a BDS. Therefore, we will need to consider this in
> bdrv_refresh_filename().
> 
> Adding a new field to the BDS is not nice, but it is very simple and
> exactly keeps track of whether the backing file has been overridden.
> 
> This commit adds a FIXME which will be remedied by a follow-up commit.
> Until then, the respective piece of code will not result in any behavior
> that is worse than what we currently have.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  include/block/block_int.h |  1 +
>  block.c                   | 13 +++++++++++++
>  block/mirror.c            |  4 ++++
>  blockdev.c                | 16 ++++++++++++++++
>  4 files changed, 34 insertions(+)

Looks like our mails crossed; I gave R-b on v3 before seeing this was
posted, and don't see any changes. To aid any automated tools:
Reviewed-by: Eric Blake <eblake@redhat.com>


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v4 04/25] block: Respect backing bs in bdrv_refresh_filename

[Eric Blake]

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On 01/11/2017 12:14 PM, Max Reitz wrote:

The mail archives show this series stopping at 4/25; what happened to 5-25?
https://lists.gnu.org/archive/html/qemu-devel/2017-01/threads.html#01912

> Basically, bdrv_refresh_filename() should respect all children of a
> BlockDriverState. However, generally those children are driver-specific,
> so this function cannot handle the general case. On the other hand,
> there are only few drivers which use other children than @file and
> @backing (that being vmdk, quorum, and blkverify).
> 
> Most block drivers only use @file and/or @backing (if they use any
> children at all). Both can be implemented directly in
> bdrv_refresh_filename.
> 
> The user overriding the file's filename is already handled, however, the
> user overriding the backing file is not. If this is done, opening the
> BDS with the plain filename of its file will not be correct, so we may
> not set bs->exact_filename in that case.
> 
> iotest 051 contains test cases for overwriting the backing file, and so
> its output changes with this patch applied (which I consider a good
> thing).
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block.c                       | 12 +++++++++++-
>  tests/qemu-iotests/051.out    |  8 ++++----
>  tests/qemu-iotests/051.pc.out |  8 ++++----
>  3 files changed, 19 insertions(+), 9 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

> +++ b/tests/qemu-iotests/051.out
> @@ -59,7 +59,7 @@ QEMU X.Y.Z monitor - type 'help' for more information
>  Testing: -drive file=TEST_DIR/t.qcow2,driver=qcow2,backing.file.filename=TEST_DIR/t.qcow2.orig,if=none,id=drive0 -nodefaults
>  QEMU X.Y.Z monitor - type 'help' for more information
>  (qemu) i^[[K^[[Din^[[K^[[D^[[Dinf^[[K^[[D^[[D^[[Dinfo^[[K^[[D^[[D^[[D^[[Dinfo ^[[K^[[D^[[D^[[D^[[D^[[Dinfo b^[[K^[[D^[[D^[[D^[[D^[[D^[[Dinfo bl^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo blo^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo bloc^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo block^[[K
> -drive0 (NODE_NAME): TEST_DIR/t.qcow2 (qcow2)
> +drive0 (NODE_NAME): json:{"backing": {"driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2.orig"}}, "driver": "qcow2", "file": {"driver": "file", "filename": "TEST_DIR/t.qcow2"}} (qcow2)

These test files are a pain to read, but I concur that the resulting
output looks better now that it is obvious that the backing file has
been overridden.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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[Qemu-devel] [PATCH v4 05/25] block: Make path_combine() return the path

[Max Reitz]

Besides being safe for arbitrary path lengths, after some follow-up
patches all callers will want a freshly allocated buffer anyway.

In the meantime, path_combine_deprecated() is added which has the same
interface as path_combine() had before this patch. All callers to that
function will be converted in follow-up patches.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 include/block/block.h |  4 +--
 block.c               | 81 +++++++++++++++++++++++++++++----------------------
 block/vmdk.c          |  3 +-
 3 files changed, 48 insertions(+), 40 deletions(-)

diff --git a/include/block/block.h b/include/block/block.h
index 49bb0b239a..6e5d4b25a4 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -444,9 +444,7 @@ void bdrv_get_full_backing_filename_from_filename(const char *backed,
 
 int path_has_protocol(const char *path);
 int path_is_absolute(const char *path);
-void path_combine(char *dest, int dest_size,
-                  const char *base_path,
-                  const char *filename);
+char *path_combine(const char *base_path, const char *filename);
 
 int bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos);
 int bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos);
diff --git a/block.c b/block.c
index f7a287a60d..28ce42c8a3 100644
--- a/block.c
+++ b/block.c
@@ -148,48 +148,59 @@ int path_is_absolute(const char *path)
 #endif
 }
 
-/* if filename is absolute, just copy it to dest. Otherwise, build a
+/* if filename is absolute, just return its duplicate. Otherwise, build a
    path to it by considering it is relative to base_path. URL are
    supported. */
-void path_combine(char *dest, int dest_size,
-                  const char *base_path,
-                  const char *filename)
+char *path_combine(const char *base_path, const char *filename)
 {
     const char *p, *p1;
+    char *result;
     int len;
 
-    if (dest_size <= 0)
-        return;
     if (path_is_absolute(filename)) {
-        pstrcpy(dest, dest_size, filename);
+        return g_strdup(filename);
+    }
+
+    p = strchr(base_path, ':');
+    if (p) {
+        p++;
     } else {
-        p = strchr(base_path, ':');
-        if (p)
-            p++;
-        else
-            p = base_path;
-        p1 = strrchr(base_path, '/');
+        p = base_path;
+    }
+    p1 = strrchr(base_path, '/');
 #ifdef _WIN32
-        {
-            const char *p2;
-            p2 = strrchr(base_path, '\\');
-            if (!p1 || p2 > p1)
-                p1 = p2;
+    {
+        const char *p2;
+        p2 = strrchr(base_path, '\\');
+        if (!p1 || p2 > p1) {
+            p1 = p2;
         }
+    }
 #endif
-        if (p1)
-            p1++;
-        else
-            p1 = base_path;
-        if (p1 > p)
-            p = p1;
-        len = p - base_path;
-        if (len > dest_size - 1)
-            len = dest_size - 1;
-        memcpy(dest, base_path, len);
-        dest[len] = '\0';
-        pstrcat(dest, dest_size, filename);
+    if (p1) {
+        p1++;
+    } else {
+        p1 = base_path;
+    }
+    if (p1 > p) {
+        p = p1;
     }
+    len = p - base_path;
+
+    result = g_malloc(len + strlen(filename) + 1);
+    memcpy(result, base_path, len);
+    strcpy(result + len, filename);
+
+    return result;
+}
+
+static void path_combine_deprecated(char *dest, int dest_size,
+                                    const char *base_path,
+                                    const char *filename)
+{
+    char *combined = path_combine(base_path, filename);
+    pstrcpy(dest, dest_size, combined);
+    g_free(combined);
 }
 
 void bdrv_get_full_backing_filename_from_filename(const char *backed,
@@ -205,7 +216,7 @@ void bdrv_get_full_backing_filename_from_filename(const char *backed,
         error_setg(errp, "Cannot use relative backing file names for '%s'",
                    backed);
     } else {
-        path_combine(dest, sz, backed, backing);
+        path_combine_deprecated(dest, sz, backed, backing);
     }
 }
 
@@ -3177,8 +3188,8 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
         } else {
             /* If not an absolute filename path, make it relative to the current
              * image's filename path */
-            path_combine(filename_tmp, PATH_MAX, curr_bs->filename,
-                         backing_file);
+            path_combine_deprecated(filename_tmp, PATH_MAX, curr_bs->filename,
+                                    backing_file);
 
             /* We are going to compare absolute pathnames */
             if (!realpath(filename_tmp, filename_full)) {
@@ -3187,8 +3198,8 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
 
             /* We need to make sure the backing filename we are comparing against
              * is relative to the current image filename (or absolute) */
-            path_combine(filename_tmp, PATH_MAX, curr_bs->filename,
-                         curr_bs->backing_file);
+            path_combine_deprecated(filename_tmp, PATH_MAX, curr_bs->filename,
+                                    curr_bs->backing_file);
 
             if (!realpath(filename_tmp, backing_file_full)) {
                 continue;
diff --git a/block/vmdk.c b/block/vmdk.c
index a11c27a1c4..aad2d7de01 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -846,8 +846,7 @@ static int vmdk_parse_extents(const char *desc, BlockDriverState *bs,
             return -EINVAL;
         }
 
-        extent_path = g_malloc0(PATH_MAX);
-        path_combine(extent_path, PATH_MAX, desc_file_path, fname);
+        extent_path = path_combine(desc_file_path, fname);
 
         ret = snprintf(extent_opt_prefix, 32, "extents.%d", s->num_extents);
         assert(ret < 32);
-- 
2.11.0

[Qemu-devel] [PATCH v4 06/25] block: bdrv_get_full_backing_filename_from_...'s ret. val.

[Max Reitz]

Make bdrv_get_full_backing_filename_from_filename() return an allocated
string instead of placing the result in a caller-provided buffer.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 include/block/block.h |  7 +++----
 block.c               | 32 +++++++++++++++++++-------------
 block/vmdk.c          |  8 +++-----
 3 files changed, 25 insertions(+), 22 deletions(-)

diff --git a/include/block/block.h b/include/block/block.h
index 6e5d4b25a4..fe16e45aba 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -437,10 +437,9 @@ void bdrv_get_backing_filename(BlockDriverState *bs,
                                char *filename, int filename_size);
 void bdrv_get_full_backing_filename(BlockDriverState *bs,
                                     char *dest, size_t sz, Error **errp);
-void bdrv_get_full_backing_filename_from_filename(const char *backed,
-                                                  const char *backing,
-                                                  char *dest, size_t sz,
-                                                  Error **errp);
+char *bdrv_get_full_backing_filename_from_filename(const char *backed,
+                                                   const char *backing,
+                                                   Error **errp);
 
 int path_has_protocol(const char *path);
 int path_is_absolute(const char *path);
diff --git a/block.c b/block.c
index 28ce42c8a3..b02e492653 100644
--- a/block.c
+++ b/block.c
@@ -203,20 +203,20 @@ static void path_combine_deprecated(char *dest, int dest_size,
     g_free(combined);
 }
 
-void bdrv_get_full_backing_filename_from_filename(const char *backed,
-                                                  const char *backing,
-                                                  char *dest, size_t sz,
-                                                  Error **errp)
+char *bdrv_get_full_backing_filename_from_filename(const char *backed,
+                                                   const char *backing,
+                                                   Error **errp)
 {
     if (backing[0] == '\0' || path_has_protocol(backing) ||
         path_is_absolute(backing))
     {
-        pstrcpy(dest, sz, backing);
+        return g_strdup(backing);
     } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
         error_setg(errp, "Cannot use relative backing file names for '%s'",
                    backed);
+        return NULL;
     } else {
-        path_combine_deprecated(dest, sz, backed, backing);
+        return path_combine(backed, backing);
     }
 }
 
@@ -224,9 +224,15 @@ void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz,
                                     Error **errp)
 {
     char *backed = bs->exact_filename[0] ? bs->exact_filename : bs->filename;
+    char *full_name;
 
-    bdrv_get_full_backing_filename_from_filename(backed, bs->backing_file,
-                                                 dest, sz, errp);
+    full_name = bdrv_get_full_backing_filename_from_filename(backed,
+                                                             bs->backing_file,
+                                                             errp);
+    if (full_name) {
+        pstrcpy(dest, sz, full_name);
+        g_free(full_name);
+    }
 }
 
 void bdrv_register(BlockDriver *bdrv)
@@ -3607,16 +3613,16 @@ void bdrv_img_create(const char *filename, const char *fmt,
     if (size == -1) {
         if (backing_file) {
             BlockDriverState *bs;
-            char *full_backing = g_new0(char, PATH_MAX);
+            char *full_backing;
             int64_t size;
             int back_flags;
             QDict *backing_options = NULL;
 
-            bdrv_get_full_backing_filename_from_filename(filename, backing_file,
-                                                         full_backing, PATH_MAX,
-                                                         &local_err);
+            full_backing =
+                bdrv_get_full_backing_filename_from_filename(filename,
+                                                             backing_file,
+                                                             &local_err);
             if (local_err) {
-                g_free(full_backing);
                 goto out;
             }
 
diff --git a/block/vmdk.c b/block/vmdk.c
index aad2d7de01..6f6932aa3f 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1973,12 +1973,10 @@ static int vmdk_create(const char *filename, QemuOpts *opts, Error **errp)
     }
     if (backing_file) {
         BlockBackend *blk;
-        char *full_backing = g_new0(char, PATH_MAX);
-        bdrv_get_full_backing_filename_from_filename(filename, backing_file,
-                                                     full_backing, PATH_MAX,
-                                                     &local_err);
+        char *full_backing =
+            bdrv_get_full_backing_filename_from_filename(filename, backing_file,
+                                                         &local_err);
         if (local_err) {
-            g_free(full_backing);
             error_propagate(errp, local_err);
             ret = -ENOENT;
             goto exit;
-- 
2.11.0

[Qemu-devel] [PATCH v4 07/25] block: bdrv_get_full_backing_filename's ret. val.

[Max Reitz]

Make bdrv_get_full_backing_filename() return an allocated string instead
of placing the result in a caller-provided buffer.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 include/block/block.h |  3 +--
 block.c               | 26 +++++++++-----------------
 block/qapi.c          | 12 ++----------
 3 files changed, 12 insertions(+), 29 deletions(-)

diff --git a/include/block/block.h b/include/block/block.h
index fe16e45aba..eb41956bf1 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -435,8 +435,7 @@ void bdrv_round_to_clusters(BlockDriverState *bs,
 const char *bdrv_get_encrypted_filename(BlockDriverState *bs);
 void bdrv_get_backing_filename(BlockDriverState *bs,
                                char *filename, int filename_size);
-void bdrv_get_full_backing_filename(BlockDriverState *bs,
-                                    char *dest, size_t sz, Error **errp);
+char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp);
 char *bdrv_get_full_backing_filename_from_filename(const char *backed,
                                                    const char *backing,
                                                    Error **errp);
diff --git a/block.c b/block.c
index b02e492653..7e60bb090b 100644
--- a/block.c
+++ b/block.c
@@ -220,19 +220,13 @@ char *bdrv_get_full_backing_filename_from_filename(const char *backed,
     }
 }
 
-void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz,
-                                    Error **errp)
+char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
 {
     char *backed = bs->exact_filename[0] ? bs->exact_filename : bs->filename;
-    char *full_name;
 
-    full_name = bdrv_get_full_backing_filename_from_filename(backed,
-                                                             bs->backing_file,
-                                                             errp);
-    if (full_name) {
-        pstrcpy(dest, sz, full_name);
-        g_free(full_name);
-    }
+    return bdrv_get_full_backing_filename_from_filename(backed,
+                                                        bs->backing_file,
+                                                        errp);
 }
 
 void bdrv_register(BlockDriver *bdrv)
@@ -1484,7 +1478,7 @@ out:
 int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
                            const char *bdref_key, Error **errp)
 {
-    char *backing_filename = g_malloc0(PATH_MAX);
+    char *backing_filename = NULL;
     char *bdref_key_dot;
     const char *reference = NULL;
     int ret = 0;
@@ -1511,7 +1505,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
 
     reference = qdict_get_try_str(parent_options, bdref_key);
     if (reference || qdict_haskey(options, "file.filename")) {
-        backing_filename[0] = '\0';
+        /* keep backing_filename NULL */
 
         /* FIXME: Should also be set to true if @options contains other runtime
          *        options which control the data that is read from the backing
@@ -1521,8 +1515,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
         QDECREF(options);
         goto free_exit;
     } else {
-        bdrv_get_full_backing_filename(bs, backing_filename, PATH_MAX,
-                                       &local_err);
+        backing_filename = bdrv_get_full_backing_filename(bs, &local_err);
         if (local_err) {
             ret = -EINVAL;
             error_propagate(errp, local_err);
@@ -1542,9 +1535,8 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
         qdict_put(options, "driver", qstring_from_str(bs->backing_format));
     }
 
-    backing_hd = bdrv_open_inherit(*backing_filename ? backing_filename : NULL,
-                                   reference, options, 0, bs, &child_backing,
-                                   errp);
+    backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs,
+                                   &child_backing, errp);
     if (!backing_hd) {
         bs->open_flags |= BDRV_O_NO_BACKING;
         error_prepend(errp, "Could not open backing file: ");
diff --git a/block/qapi.c b/block/qapi.c
index a62e862f3c..1543dd691a 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -265,18 +265,10 @@ void bdrv_query_image_info(BlockDriverState *bs,
 
     backing_filename = bs->backing_file;
     if (backing_filename[0] != '\0') {
-        char *backing_filename2 = g_malloc0(PATH_MAX);
+        char *backing_filename2;
         info->backing_filename = g_strdup(backing_filename);
         info->has_backing_filename = true;
-        bdrv_get_full_backing_filename(bs, backing_filename2, PATH_MAX, &err);
-        if (err) {
-            /* Can't reconstruct the full backing filename, so we must omit
-             * this field and apply a Best Effort to this query. */
-            g_free(backing_filename2);
-            backing_filename2 = NULL;
-            error_free(err);
-            err = NULL;
-        }
+        backing_filename2 = bdrv_get_full_backing_filename(bs, NULL);
 
         /* Always report the full_backing_filename if present, even if it's the
          * same as backing_filename. That they are same is useful info. */
-- 
2.11.0

[Qemu-devel] [PATCH v4 08/25] block: Add bdrv_make_absolute_filename()

[Max Reitz]

This is a general function for making a filename that is relative to a
certain BDS absolute.

It calls bdrv_get_full_backing_filename_from_filename() for now, but
that will be changed in a follow-up patch.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
---
 block.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/block.c b/block.c
index 7e60bb090b..4ad561810f 100644
--- a/block.c
+++ b/block.c
@@ -220,15 +220,22 @@ char *bdrv_get_full_backing_filename_from_filename(const char *backed,
     }
 }
 
-char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
+static char *bdrv_make_absolute_filename(BlockDriverState *relative_to,
+                                         const char *filename, Error **errp)
 {
-    char *backed = bs->exact_filename[0] ? bs->exact_filename : bs->filename;
+    char *bs_filename = relative_to->exact_filename[0]
+                        ? relative_to->exact_filename
+                        : relative_to->filename;
 
-    return bdrv_get_full_backing_filename_from_filename(backed,
-                                                        bs->backing_file,
+    return bdrv_get_full_backing_filename_from_filename(bs_filename, filename,
                                                         errp);
 }
 
+char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
+{
+    return bdrv_make_absolute_filename(bs, bs->backing_file, errp);
+}
+
 void bdrv_register(BlockDriver *bdrv)
 {
     QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
-- 
2.11.0

[Qemu-devel] [PATCH v4 09/25] block: Fix bdrv_find_backing_image()

[Max Reitz]

bdrv_find_backing_image() should use bdrv_get_full_backing_filename() or
bdrv_make_absolute_filename() instead of trying to do what those
functions do by itself.

path_combine_deprecated() can now be dropped, so let's do that.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/block.c b/block.c
index 4ad561810f..2735ec4bcc 100644
--- a/block.c
+++ b/block.c
@@ -194,15 +194,6 @@ char *path_combine(const char *base_path, const char *filename)
     return result;
 }
 
-static void path_combine_deprecated(char *dest, int dest_size,
-                                    const char *base_path,
-                                    const char *filename)
-{
-    char *combined = path_combine(base_path, filename);
-    pstrcpy(dest, dest_size, combined);
-    g_free(combined);
-}
-
 char *bdrv_get_full_backing_filename_from_filename(const char *backed,
                                                    const char *backing,
                                                    Error **errp)
@@ -3177,7 +3168,6 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
 
     filename_full     = g_malloc(PATH_MAX);
     backing_file_full = g_malloc(PATH_MAX);
-    filename_tmp      = g_malloc(PATH_MAX);
 
     is_protocol = path_has_protocol(backing_file);
 
@@ -3193,22 +3183,31 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
         } else {
             /* If not an absolute filename path, make it relative to the current
              * image's filename path */
-            path_combine_deprecated(filename_tmp, PATH_MAX, curr_bs->filename,
-                                    backing_file);
+            filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file,
+                                                       NULL);
+            if (!filename_tmp) {
+                continue;
+            }
 
             /* We are going to compare absolute pathnames */
             if (!realpath(filename_tmp, filename_full)) {
+                g_free(filename_tmp);
                 continue;
             }
+            g_free(filename_tmp);
 
             /* We need to make sure the backing filename we are comparing against
              * is relative to the current image filename (or absolute) */
-            path_combine_deprecated(filename_tmp, PATH_MAX, curr_bs->filename,
-                                    curr_bs->backing_file);
+            filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL);
+            if (!filename_tmp) {
+                continue;
+            }
 
             if (!realpath(filename_tmp, backing_file_full)) {
+                g_free(filename_tmp);
                 continue;
             }
+            g_free(filename_tmp);
 
             if (strcmp(backing_file_full, filename_full) == 0) {
                 retval = curr_bs->backing->bs;
@@ -3219,7 +3218,6 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
 
     g_free(filename_full);
     g_free(backing_file_full);
-    g_free(filename_tmp);
     return retval;
 }
 
-- 
2.11.0

[Qemu-devel] [PATCH v4 10/25] block: Add bdrv_dirname()

[Max Reitz]

This function may be implemented by block drivers to derive a directory
name from a BDS. Concatenating this g_free()-able string with a relative
filename must result in a valid (not necessarily existing) filename, so
this is a function that should generally be not implemented by format
drivers, because this is protocol-specific.

If a BDS's driver does not implement this function, bdrv_dirname() will
fall through to the BDS's file if it exists. If it does not, the
exact_filename field will be used to generate a directory name.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 include/block/block.h     |  1 +
 include/block/block_int.h |  1 +
 block.c                   | 26 ++++++++++++++++++++++++++
 3 files changed, 28 insertions(+)

diff --git a/include/block/block.h b/include/block/block.h
index eb41956bf1..7bcbd05338 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -439,6 +439,7 @@ char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp);
 char *bdrv_get_full_backing_filename_from_filename(const char *backed,
                                                    const char *backing,
                                                    Error **errp);
+char *bdrv_dirname(BlockDriverState *bs, Error **errp);
 
 int path_has_protocol(const char *path);
 int path_is_absolute(const char *path);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index c1f057ab47..fb916a7890 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -130,6 +130,7 @@ struct BlockDriver {
     int (*bdrv_make_empty)(BlockDriverState *bs);
 
     void (*bdrv_refresh_filename)(BlockDriverState *bs, QDict *options);
+    char *(*bdrv_dirname)(BlockDriverState *bs, Error **errp);
 
     /* aio */
     BlockAIOCB *(*bdrv_aio_readv)(BlockDriverState *bs,
diff --git a/block.c b/block.c
index 2735ec4bcc..e591e326c5 100644
--- a/block.c
+++ b/block.c
@@ -4083,6 +4083,32 @@ void bdrv_refresh_filename(BlockDriverState *bs)
     }
 }
 
+char *bdrv_dirname(BlockDriverState *bs, Error **errp)
+{
+    BlockDriver *drv = bs->drv;
+
+    if (!drv) {
+        error_setg(errp, "Node '%s' is ejected", bs->node_name);
+        return NULL;
+    }
+
+    if (drv->bdrv_dirname) {
+        return drv->bdrv_dirname(bs, errp);
+    }
+
+    if (bs->file) {
+        return bdrv_dirname(bs->file->bs, errp);
+    }
+
+    if (bs->exact_filename[0] != '\0') {
+        return path_combine(bs->exact_filename, "");
+    }
+
+    error_setg(errp, "Cannot generate a base directory for %s nodes",
+               drv->format_name);
+    return NULL;
+}
+
 /*
  * Hot add/remove a BDS's child. So the user can take a child offline when
  * it is broken and take a new child online
-- 
2.11.0

[Qemu-devel] [PATCH v4 11/25] blkverify: Make bdrv_dirname() return NULL

[Max Reitz]

blkverify's BDSs have a file BDS, but we do not want this to be
preferred over the raw node. There is no way to decide between the two
(and not really a reason to, either), so just return NULL in blkverify's
implementation of bdrv_dirname().

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/blkverify.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/block/blkverify.c b/block/blkverify.c
index 38a8c68029..c72a1fba64 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -309,6 +309,15 @@ static void blkverify_refresh_filename(BlockDriverState *bs, QDict *options)
     }
 }
 
+static char *blkverify_dirname(BlockDriverState *bs, Error **errp)
+{
+    /* In general, there are two BDSs with different dirnames below this one;
+     * so there is no unique dirname we could return (unless both are equal by
+     * chance). Therefore, to be consistent, just always return NULL. */
+    error_setg(errp, "Cannot generate a base directory for blkverify nodes");
+    return NULL;
+}
+
 static BlockDriver bdrv_blkverify = {
     .format_name                      = "blkverify",
     .protocol_name                    = "blkverify",
@@ -319,6 +328,7 @@ static BlockDriver bdrv_blkverify = {
     .bdrv_close                       = blkverify_close,
     .bdrv_getlength                   = blkverify_getlength,
     .bdrv_refresh_filename            = blkverify_refresh_filename,
+    .bdrv_dirname                     = blkverify_dirname,
 
     .bdrv_co_preadv                   = blkverify_co_preadv,
     .bdrv_co_pwritev                  = blkverify_co_pwritev,
-- 
2.11.0

[Qemu-devel] [PATCH v4 12/25] quorum: Make bdrv_dirname() return NULL

[Max Reitz]

While the common implementation for bdrv_dirname() should return NULL
for quorum BDSs already (because they do not have a file node and their
exact_filename field should be empty), there is no reason not to make
that explicit.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/quorum.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/block/quorum.c b/block/quorum.c
index 112370eea2..3b5da08ec3 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1105,6 +1105,16 @@ static void quorum_refresh_filename(BlockDriverState *bs, QDict *options)
     bs->full_open_options = opts;
 }
 
+static char *quorum_dirname(BlockDriverState *bs, Error **errp)
+{
+    /* In general, there are multiple BDSs with different dirnames below this
+     * one; so there is no unique dirname we could return (unless all are equal
+     * by chance, or there is only one). Therefore, to be consistent, just
+     * always return NULL. */
+    error_setg(errp, "Cannot generate a base directory for quorum nodes");
+    return NULL;
+}
+
 static BlockDriver bdrv_quorum = {
     .format_name                        = "quorum",
     .protocol_name                      = "quorum",
@@ -1114,6 +1124,7 @@ static BlockDriver bdrv_quorum = {
     .bdrv_file_open                     = quorum_open,
     .bdrv_close                         = quorum_close,
     .bdrv_refresh_filename              = quorum_refresh_filename,
+    .bdrv_dirname                       = quorum_dirname,
 
     .bdrv_co_flush_to_disk              = quorum_co_flush,
 
-- 
2.11.0

[Qemu-devel] [PATCH v4 13/25] block/nbd: Implement bdrv_dirname()

[Max Reitz]

The idea behind this implementation is that the export name might be
interpreted as a path (which is the only apparent interpretation of
relative filenames for NBD paths).

The default implementation of bdrv_dirname() would handle that just fine
for nbd+tcp, but not for nbd+unix, because in that case, the last
element of the path is the Unix socket path and not the export name.
Therefore, we need to implement an own bdrv_dirname() which uses the
legacy NBD URL which has the export name at the end.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/nbd.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/block/nbd.c b/block/nbd.c
index 35f24be069..42f0cd638c 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -552,6 +552,34 @@ static void nbd_refresh_filename(BlockDriverState *bs, QDict *options)
     bs->full_open_options = opts;
 }
 
+static char *nbd_dirname(BlockDriverState *bs, Error **errp)
+{
+    BDRVNBDState *s = bs->opaque;
+    const char *host = NULL, *port = NULL, *path = NULL;
+
+    if (s->saddr->type == SOCKET_ADDRESS_KIND_INET) {
+        const InetSocketAddress *inet = s->saddr->u.inet.data;
+        if (!inet->has_ipv4 && !inet->has_ipv6 && !inet->has_to) {
+            host = inet->host;
+            port = inet->port;
+        }
+    } else if (s->saddr->type == SOCKET_ADDRESS_KIND_UNIX) {
+        path = s->saddr->u.q_unix.data->path;
+    }
+
+    if (path) {
+        return g_strdup_printf("nbd:unix:%s:exportname=%s%s", path,
+                               s->export ?: "", s->export ? "/" : "");
+    } else if (host) {
+        return g_strdup_printf("nbd://%s:%s/%s%s", host, port,
+                               s->export ?: "", s->export ? "/" : "");
+    }
+
+    error_setg(errp, "Cannot generate a base directory for NBD node '%s'",
+               bs->filename);
+    return NULL;
+}
+
 static BlockDriver bdrv_nbd = {
     .format_name                = "nbd",
     .protocol_name              = "nbd",
@@ -569,6 +597,7 @@ static BlockDriver bdrv_nbd = {
     .bdrv_detach_aio_context    = nbd_detach_aio_context,
     .bdrv_attach_aio_context    = nbd_attach_aio_context,
     .bdrv_refresh_filename      = nbd_refresh_filename,
+    .bdrv_dirname               = nbd_dirname,
 };
 
 static BlockDriver bdrv_nbd_tcp = {
@@ -588,6 +617,7 @@ static BlockDriver bdrv_nbd_tcp = {
     .bdrv_detach_aio_context    = nbd_detach_aio_context,
     .bdrv_attach_aio_context    = nbd_attach_aio_context,
     .bdrv_refresh_filename      = nbd_refresh_filename,
+    .bdrv_dirname               = nbd_dirname,
 };
 
 static BlockDriver bdrv_nbd_unix = {
@@ -607,6 +637,7 @@ static BlockDriver bdrv_nbd_unix = {
     .bdrv_detach_aio_context    = nbd_detach_aio_context,
     .bdrv_attach_aio_context    = nbd_attach_aio_context,
     .bdrv_refresh_filename      = nbd_refresh_filename,
+    .bdrv_dirname               = nbd_dirname,
 };
 
 static void bdrv_nbd_init(void)
-- 
2.11.0

[Qemu-devel] [PATCH v4 14/25] block/nfs: Implement bdrv_dirname()

[Max Reitz]

While the basic idea is obvious and could be handled by the default
bdrv_dirname() implementation, we cannot generate a directory name if
the gid or uid are set, so we have to explicitly return NULL in those
cases.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/nfs.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/block/nfs.c b/block/nfs.c
index a564340d15..a6addff557 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -829,6 +829,19 @@ static void nfs_refresh_filename(BlockDriverState *bs, QDict *options)
     bs->full_open_options = opts;
 }
 
+static char *nfs_dirname(BlockDriverState *bs, Error **errp)
+{
+    NFSClient *client = bs->opaque;
+
+    if (client->uid || client->gid) {
+        error_setg(errp, "Cannot generate a base directory for NBD node '%s'",
+                   bs->filename);
+        return NULL;
+    }
+
+    return g_strdup_printf("nfs://%s%s/", client->server->host, client->path);
+}
+
 #ifdef LIBNFS_FEATURE_PAGECACHE
 static void nfs_invalidate_cache(BlockDriverState *bs,
                                  Error **errp)
@@ -862,6 +875,7 @@ static BlockDriver bdrv_nfs = {
     .bdrv_detach_aio_context        = nfs_detach_aio_context,
     .bdrv_attach_aio_context        = nfs_attach_aio_context,
     .bdrv_refresh_filename          = nfs_refresh_filename,
+    .bdrv_dirname                   = nfs_dirname,
 
 #ifdef LIBNFS_FEATURE_PAGECACHE
     .bdrv_invalidate_cache          = nfs_invalidate_cache,
-- 
2.11.0

[Qemu-devel] [PATCH v4 15/25] block: Use bdrv_dirname() for relative filenames

[Max Reitz]

bdrv_get_full_backing_filename_from_filename() breaks down when it comes
to JSON filenames. Using bdrv_dirname() as the basis is better because
since we have BDS, we can descend through the BDS tree to the protocol
layer, which gives us a greater probability of finding a non-JSON name;
also, bdrv_dirname() is more correct as it allows block drivers to
override the generation of that directory name in a protocol-specific
way.

We still need to keep bdrv_get_full_backing_filename_from_filename(),
though, because it has valid callers which need it during image creation
when no BDS is available yet.

This makes a test case in qemu-iotest 110, which was supposed to fail,
work. That is actually good, but we need to change the reference output
(and the comment in 110) accordingly.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c                    | 20 +++++++++++++++-----
 tests/qemu-iotests/110     |  3 ++-
 tests/qemu-iotests/110.out |  2 +-
 3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/block.c b/block.c
index e591e326c5..f3d4436c9e 100644
--- a/block.c
+++ b/block.c
@@ -214,12 +214,22 @@ char *bdrv_get_full_backing_filename_from_filename(const char *backed,
 static char *bdrv_make_absolute_filename(BlockDriverState *relative_to,
                                          const char *filename, Error **errp)
 {
-    char *bs_filename = relative_to->exact_filename[0]
-                        ? relative_to->exact_filename
-                        : relative_to->filename;
+    char *dir, *full_name;
 
-    return bdrv_get_full_backing_filename_from_filename(bs_filename, filename,
-                                                        errp);
+    if (filename[0] == '\0' || path_has_protocol(filename) ||
+        path_is_absolute(filename))
+    {
+        return g_strdup(filename);
+    }
+
+    dir = bdrv_dirname(relative_to, errp);
+    if (!dir) {
+        return NULL;
+    }
+
+    full_name = g_strconcat(dir, filename, NULL);
+    g_free(dir);
+    return full_name;
 }
 
 char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
diff --git a/tests/qemu-iotests/110 b/tests/qemu-iotests/110
index 9de7369f3a..ba1b3c6c7d 100755
--- a/tests/qemu-iotests/110
+++ b/tests/qemu-iotests/110
@@ -61,7 +61,8 @@ echo '=== Non-reconstructable filename ==='
 echo
 
 # Across blkdebug without a config file, you cannot reconstruct filenames, so
-# qemu is incapable of knowing the directory of the top image
+# qemu is incapable of knowing the directory of the top image from the filename
+# alone. However, using bdrv_dirname(), it should still work.
 TEST_IMG="json:{
     'driver': '$IMGFMT',
     'file': {
diff --git a/tests/qemu-iotests/110.out b/tests/qemu-iotests/110.out
index b3584ff87f..5370bc1d26 100644
--- a/tests/qemu-iotests/110.out
+++ b/tests/qemu-iotests/110.out
@@ -14,7 +14,7 @@ backing file: t.IMGFMT.base (actual path: TEST_DIR/t.IMGFMT.base)
 image: json:{"driver": "IMGFMT", "file": {"set-state.0.event": "read_aio", "image": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, "driver": "blkdebug", "set-state.0.new_state": 42}}
 file format: IMGFMT
 virtual size: 64M (67108864 bytes)
-backing file: t.IMGFMT.base (cannot determine actual path)
+backing file: t.IMGFMT.base (actual path: TEST_DIR/t.IMGFMT.base)
 
 === Backing name is always relative to the backed image ===
 
-- 
2.11.0

[Qemu-devel] [PATCH v4 16/25] block: Add 'base-directory' BDS option

[Max Reitz]

Using this option, one can directly override what bdrv_dirname() will
return. This is useful if one uses e.g. qcow2 on top of quorum (with
only protocol BDSs under the quorum BDS) and wants to be able to use
relative backing filenames.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 qapi/block-core.json      |  9 +++++++++
 include/block/block_int.h |  2 ++
 block.c                   | 14 ++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/qapi/block-core.json b/qapi/block-core.json
index 6b42216960..b4bd941696 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2367,6 +2367,14 @@
 #                 (default: false)
 # @detect-zeroes: #optional detect and optimize zero writes (Since 2.1)
 #                 (default: off)
+# @base-directory #optional May be specified for any node. Normally, whenever a
+#                 filename is specified which is supposed to be relative to this
+#                 node (such as relative backing filenames), the base directory
+#                 to be used is the directory the image file of this node is in,
+#                 which is simply prepended to the relative filename. Using this
+#                 option, the string which is prepended (i.e. the base
+#                 directory) can be overridden.
+#                 (Since 2.9)
 #
 # Remaining options are determined by the block driver.
 #
@@ -2375,6 +2383,7 @@
 { 'union': 'BlockdevOptions',
   'base': { 'driver': 'BlockdevDriver',
             '*node-name': 'str',
+            '*base-directory': 'str',
             '*discard': 'BlockdevDiscardOptions',
             '*cache': 'BlockdevCacheOptions',
             '*read-only': 'bool',
diff --git a/include/block/block_int.h b/include/block/block_int.h
index fb916a7890..30fc1def4a 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -467,6 +467,8 @@ struct BlockDriverState {
     QDict *full_open_options;
     char exact_filename[PATH_MAX];
 
+    char *dirname;
+
     BdrvChild *backing;
     BdrvChild *file;
 
diff --git a/block.c b/block.c
index f3d4436c9e..a10ba111bc 100644
--- a/block.c
+++ b/block.c
@@ -984,6 +984,12 @@ QemuOptsList bdrv_runtime_opts = {
             .type = QEMU_OPT_STRING,
             .help = "discard operation (ignore/off, unmap/on)",
         },
+        {
+            .name = "base-directory",
+            .type = QEMU_OPT_STRING,
+            .help = "String to prepend to filenames relative to this BDS for "
+                    "making them absolute",
+        },
         { /* end of list */ }
     },
 };
@@ -1047,6 +1053,8 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file,
         goto fail_opts;
     }
 
+    bs->dirname = g_strdup(qemu_opt_get(opts, "base-directory"));
+
     bs->read_only = !(bs->open_flags & BDRV_O_RDWR);
 
     if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, bs->read_only)) {
@@ -2490,6 +2498,8 @@ static void bdrv_delete(BlockDriverState *bs)
 
     bdrv_close(bs);
 
+    g_free(bs->dirname);
+
     /* remove from list, if necessary */
     if (bs->node_name[0] != '\0') {
         QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
@@ -4097,6 +4107,10 @@ char *bdrv_dirname(BlockDriverState *bs, Error **errp)
 {
     BlockDriver *drv = bs->drv;
 
+    if (bs->dirname) {
+        return g_strdup(bs->dirname);
+    }
+
     if (!drv) {
         error_setg(errp, "Node '%s' is ejected", bs->node_name);
         return NULL;
-- 
2.11.0

[Qemu-devel] [PATCH v4 17/25] iotests: Add quorum case to test 110

[Max Reitz]

Test 110 tests relative backing filenames for complex BDS trees. Add
quorum as an example that can never work automatically (without
special-casing if all child nodes have the same base directory), and an
example on how to make it work manually (using the base-directory
option).

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 tests/qemu-iotests/110     | 48 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/110.out | 12 ++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/tests/qemu-iotests/110 b/tests/qemu-iotests/110
index ba1b3c6c7d..d96b656b6b 100755
--- a/tests/qemu-iotests/110
+++ b/tests/qemu-iotests/110
@@ -30,6 +30,7 @@ status=1	# failure is the default!
 _cleanup()
 {
 	_cleanup_test_img
+        rm -f "$TEST_IMG.copy"
 }
 trap "_cleanup; exit \$status" 0 1 2 3 15
 
@@ -87,6 +88,53 @@ echo
 # omit the image size; it should work anyway
 _make_test_img -b "$TEST_IMG_REL.base"
 
+echo
+echo '=== Nodes without a common directory ==='
+echo
+
+cp "$TEST_IMG" "$TEST_IMG.copy"
+
+# Should inform us that the actual path of the backing file cannot be determined
+TEST_IMG="json:{
+    'driver': '$IMGFMT',
+    'file': {
+        'driver': 'quorum',
+        'vote-threshold': 1,
+        'children': [
+            {
+                'driver': 'file',
+                'filename': '$TEST_IMG'
+            },
+            {
+                'driver': 'file',
+                'filename': '$TEST_IMG.copy'
+            }
+        ]
+    }
+}" _img_info | _filter_img_info
+
+echo
+
+# Should work fine
+TEST_IMG="json:{
+    'driver': '$IMGFMT',
+    'file': {
+        'driver': 'quorum',
+        'base-directory': '$TEST_DIR/',
+        'vote-threshold': 1,
+        'children': [
+            {
+                'driver': 'file',
+                'filename': '$TEST_IMG'
+            },
+            {
+                'driver': 'file',
+                'filename': '$TEST_IMG.copy'
+            }
+        ]
+    }
+}" _img_info | _filter_img_info
+
 
 # success, all done
 echo '*** done'
diff --git a/tests/qemu-iotests/110.out b/tests/qemu-iotests/110.out
index 5370bc1d26..e1845d8026 100644
--- a/tests/qemu-iotests/110.out
+++ b/tests/qemu-iotests/110.out
@@ -19,4 +19,16 @@ backing file: t.IMGFMT.base (actual path: TEST_DIR/t.IMGFMT.base)
 === Backing name is always relative to the backed image ===
 
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=t.IMGFMT.base
+
+=== Nodes without a common directory ===
+
+image: json:{"driver": "IMGFMT", "file": {"children": [{"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.copy"}], "driver": "quorum", "blkverify": false, "rewrite-corrupted": false, "vote-threshold": 1}}
+file format: IMGFMT
+virtual size: 64M (67108864 bytes)
+backing file: t.IMGFMT.base (cannot determine actual path)
+
+image: json:{"driver": "IMGFMT", "file": {"children": [{"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.copy"}], "driver": "quorum", "blkverify": false, "rewrite-corrupted": false, "vote-threshold": 1}}
+file format: IMGFMT
+virtual size: 64M (67108864 bytes)
+backing file: t.IMGFMT.base (actual path: TEST_DIR/t.IMGFMT.base)
 *** done
-- 
2.11.0

Re: [Qemu-devel] [PATCH v4 04/25] block: Respect backing bs in bdrv_refresh_filename

[Max Reitz]

[-- Attachment #1: Type: text/plain, Size: 349 bytes --]

On 16.01.2017 21:43, Eric Blake wrote:
> On 01/11/2017 12:14 PM, Max Reitz wrote:
> 
> The mail archives show this series stopping at 4/25; what happened to 5-25?
> https://lists.gnu.org/archive/html/qemu-devel/2017-01/threads.html#01912

Oops. Somehow, the Red Hat mail server really hates me recently... I'll
try to get them out.

Max


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 512 bytes --]

[Qemu-devel] [PATCH v4 18/25] block: Add sgfnt_runtime_opts to BlockDriver

[Max Reitz]

This new field can be set by block drivers to list the runtime options
they accept that may influence the contents of the respective BDS. As of
a follow-up patch, this list will be used by the common
bdrv_refresh_filename() implementation to decide which options to put
into BDS.full_open_options (and consequently whether a JSON filename has
to be created), thus freeing the drivers of having to implement that
logic themselves.

Additionally, this patch adds the field to all of the block drivers that
need it and sets it accordingly.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 include/block/block_int.h |  7 +++++++
 block/blkdebug.c          |  6 ++++++
 block/curl.c              | 20 ++++++++++++++++++++
 block/gluster.c           | 19 +++++++++++++++++++
 block/nbd.c               |  8 ++++++++
 block/nfs.c               |  3 +++
 block/null.c              |  9 +++++++++
 block/quorum.c            |  8 ++++++++
 block/rbd.c               |  2 ++
 block/vvfat.c             |  4 ++++
 10 files changed, 86 insertions(+)

diff --git a/include/block/block_int.h b/include/block/block_int.h
index 30fc1def4a..799c892558 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -322,6 +322,13 @@ struct BlockDriver {
                            Error **errp);
 
     QLIST_ENTRY(BlockDriver) list;
+
+    /* Pointer to a NULL-terminated array of names of significant options that
+     * can be specified for bdrv_open(). A significant option is one that
+     * changes the data of a BDS.
+     * If this pointer is NULL, the array is considered empty.
+     * "filename" and "driver" are always considered significant. */
+    const char *const *sgfnt_runtime_opts;
 };
 
 typedef struct BlockLimits {
diff --git a/block/blkdebug.c b/block/blkdebug.c
index acccf85666..1551b2099a 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -756,6 +756,12 @@ static BlockDriver bdrv_blkdebug = {
                                 = blkdebug_debug_remove_breakpoint,
     .bdrv_debug_resume          = blkdebug_debug_resume,
     .bdrv_debug_is_suspended    = blkdebug_debug_is_suspended,
+
+    .sgfnt_runtime_opts         = (const char *const[]) { "config",
+                                                          "inject-error.",
+                                                          "set-state.",
+                                                          "suspend.",
+                                                          NULL },
 };
 
 static void bdrv_blkdebug_init(void)
diff --git a/block/curl.c b/block/curl.c
index 792fef8269..34a5b0f7e3 100644
--- a/block/curl.c
+++ b/block/curl.c
@@ -872,6 +872,18 @@ static int64_t curl_getlength(BlockDriverState *bs)
     return s->len;
 }
 
+static const char *const curl_sgfnt_runtime_opts[] = {
+    CURL_BLOCK_OPT_URL,
+    CURL_BLOCK_OPT_SSLVERIFY,
+    CURL_BLOCK_OPT_COOKIE,
+    CURL_BLOCK_OPT_USERNAME,
+    CURL_BLOCK_OPT_PASSWORD_SECRET,
+    CURL_BLOCK_OPT_PROXY_USERNAME,
+    CURL_BLOCK_OPT_PROXY_PASSWORD_SECRET,
+
+    NULL
+};
+
 static BlockDriver bdrv_http = {
     .format_name                = "http",
     .protocol_name              = "http",
@@ -886,6 +898,8 @@ static BlockDriver bdrv_http = {
 
     .bdrv_detach_aio_context    = curl_detach_aio_context,
     .bdrv_attach_aio_context    = curl_attach_aio_context,
+
+    .sgfnt_runtime_opts         = curl_sgfnt_runtime_opts,
 };
 
 static BlockDriver bdrv_https = {
@@ -902,6 +916,8 @@ static BlockDriver bdrv_https = {
 
     .bdrv_detach_aio_context    = curl_detach_aio_context,
     .bdrv_attach_aio_context    = curl_attach_aio_context,
+
+    .sgfnt_runtime_opts         = curl_sgfnt_runtime_opts,
 };
 
 static BlockDriver bdrv_ftp = {
@@ -918,6 +934,8 @@ static BlockDriver bdrv_ftp = {
 
     .bdrv_detach_aio_context    = curl_detach_aio_context,
     .bdrv_attach_aio_context    = curl_attach_aio_context,
+
+    .sgfnt_runtime_opts         = curl_sgfnt_runtime_opts,
 };
 
 static BlockDriver bdrv_ftps = {
@@ -934,6 +952,8 @@ static BlockDriver bdrv_ftps = {
 
     .bdrv_detach_aio_context    = curl_detach_aio_context,
     .bdrv_attach_aio_context    = curl_attach_aio_context,
+
+    .sgfnt_runtime_opts         = curl_sgfnt_runtime_opts,
 };
 
 static void curl_block_init(void)
diff --git a/block/gluster.c b/block/gluster.c
index 1a22f2982d..ded13fb5fb 100644
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -1402,6 +1402,21 @@ static int64_t coroutine_fn qemu_gluster_co_get_block_status(
 }
 
 
+static const char *const gluster_sgfnt_open_opts[] = {
+    GLUSTER_OPT_VOLUME,
+    GLUSTER_OPT_PATH,
+    GLUSTER_OPT_TYPE,
+    GLUSTER_OPT_SERVER_PATTERN,
+    GLUSTER_OPT_HOST,
+    GLUSTER_OPT_PORT,
+    GLUSTER_OPT_TO,
+    GLUSTER_OPT_IPV4,
+    GLUSTER_OPT_IPV6,
+    GLUSTER_OPT_SOCKET,
+
+    NULL
+};
+
 static BlockDriver bdrv_gluster = {
     .format_name                  = "gluster",
     .protocol_name                = "gluster",
@@ -1428,6 +1443,7 @@ static BlockDriver bdrv_gluster = {
 #endif
     .bdrv_co_get_block_status     = qemu_gluster_co_get_block_status,
     .create_opts                  = &qemu_gluster_create_opts,
+    .sgfnt_runtime_opts           = gluster_sgfnt_open_opts,
 };
 
 static BlockDriver bdrv_gluster_tcp = {
@@ -1456,6 +1472,7 @@ static BlockDriver bdrv_gluster_tcp = {
 #endif
     .bdrv_co_get_block_status     = qemu_gluster_co_get_block_status,
     .create_opts                  = &qemu_gluster_create_opts,
+    .sgfnt_runtime_opts           = gluster_sgfnt_open_opts,
 };
 
 static BlockDriver bdrv_gluster_unix = {
@@ -1484,6 +1501,7 @@ static BlockDriver bdrv_gluster_unix = {
 #endif
     .bdrv_co_get_block_status     = qemu_gluster_co_get_block_status,
     .create_opts                  = &qemu_gluster_create_opts,
+    .sgfnt_runtime_opts           = gluster_sgfnt_open_opts,
 };
 
 /* rdma is deprecated (actually never supported for volfile fetch).
@@ -1518,6 +1536,7 @@ static BlockDriver bdrv_gluster_rdma = {
 #endif
     .bdrv_co_get_block_status     = qemu_gluster_co_get_block_status,
     .create_opts                  = &qemu_gluster_create_opts,
+    .sgfnt_runtime_opts           = gluster_sgfnt_open_opts,
 };
 
 static void bdrv_gluster_init(void)
diff --git a/block/nbd.c b/block/nbd.c
index 42f0cd638c..130798903f 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -580,6 +580,11 @@ static char *nbd_dirname(BlockDriverState *bs, Error **errp)
     return NULL;
 }
 
+static const char *const nbd_sgfnt_runtime_opts[] = {
+    "path", "host", "port", "export", "tls-creds", "server.",
+    NULL
+};
+
 static BlockDriver bdrv_nbd = {
     .format_name                = "nbd",
     .protocol_name              = "nbd",
@@ -598,6 +603,7 @@ static BlockDriver bdrv_nbd = {
     .bdrv_attach_aio_context    = nbd_attach_aio_context,
     .bdrv_refresh_filename      = nbd_refresh_filename,
     .bdrv_dirname               = nbd_dirname,
+    .sgfnt_runtime_opts         = nbd_sgfnt_runtime_opts,
 };
 
 static BlockDriver bdrv_nbd_tcp = {
@@ -618,6 +624,7 @@ static BlockDriver bdrv_nbd_tcp = {
     .bdrv_attach_aio_context    = nbd_attach_aio_context,
     .bdrv_refresh_filename      = nbd_refresh_filename,
     .bdrv_dirname               = nbd_dirname,
+    .sgfnt_runtime_opts         = nbd_sgfnt_runtime_opts,
 };
 
 static BlockDriver bdrv_nbd_unix = {
@@ -638,6 +645,7 @@ static BlockDriver bdrv_nbd_unix = {
     .bdrv_attach_aio_context    = nbd_attach_aio_context,
     .bdrv_refresh_filename      = nbd_refresh_filename,
     .bdrv_dirname               = nbd_dirname,
+    .sgfnt_runtime_opts         = nbd_sgfnt_runtime_opts,
 };
 
 static void bdrv_nbd_init(void)
diff --git a/block/nfs.c b/block/nfs.c
index a6addff557..d4ca2757a1 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -877,6 +877,9 @@ static BlockDriver bdrv_nfs = {
     .bdrv_refresh_filename          = nfs_refresh_filename,
     .bdrv_dirname                   = nfs_dirname,
 
+    .sgfnt_runtime_opts             = (const char *const[]) { "path", "uid",
+                                                              "gid", NULL },
+
 #ifdef LIBNFS_FEATURE_PAGECACHE
     .bdrv_invalidate_cache          = nfs_invalidate_cache,
 #endif
diff --git a/block/null.c b/block/null.c
index b300390944..16ef8b2a09 100644
--- a/block/null.c
+++ b/block/null.c
@@ -236,6 +236,13 @@ static void null_refresh_filename(BlockDriverState *bs, QDict *opts)
     bs->full_open_options = opts;
 }
 
+static const char *const null_sgfnt_runtime_opts[] = {
+    BLOCK_OPT_SIZE,
+    NULL_OPT_ZEROES,
+
+    NULL
+};
+
 static BlockDriver bdrv_null_co = {
     .format_name            = "null-co",
     .protocol_name          = "null-co",
@@ -253,6 +260,7 @@ static BlockDriver bdrv_null_co = {
     .bdrv_co_get_block_status   = null_co_get_block_status,
 
     .bdrv_refresh_filename  = null_refresh_filename,
+    .sgfnt_runtime_opts     = null_sgfnt_runtime_opts,
 };
 
 static BlockDriver bdrv_null_aio = {
@@ -272,6 +280,7 @@ static BlockDriver bdrv_null_aio = {
     .bdrv_co_get_block_status   = null_co_get_block_status,
 
     .bdrv_refresh_filename  = null_refresh_filename,
+    .sgfnt_runtime_opts     = null_sgfnt_runtime_opts,
 };
 
 static void bdrv_null_init(void)
diff --git a/block/quorum.c b/block/quorum.c
index 3b5da08ec3..878b8cfa9a 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1138,6 +1138,14 @@ static BlockDriver bdrv_quorum = {
 
     .is_filter                          = true,
     .bdrv_recurse_is_first_non_filter   = quorum_recurse_is_first_non_filter,
+
+    .sgfnt_runtime_opts                 = (const char *const[]) {
+                                              QUORUM_OPT_VOTE_THRESHOLD,
+                                              QUORUM_OPT_BLKVERIFY,
+                                              QUORUM_OPT_REWRITE,
+                                              QUORUM_OPT_READ_PATTERN,
+                                              NULL
+                                          },
 };
 
 static void bdrv_quorum_init(void)
diff --git a/block/rbd.c b/block/rbd.c
index a57b3e3c5d..b09a18f097 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -1005,6 +1005,8 @@ static BlockDriver bdrv_rbd = {
 #ifdef LIBRBD_SUPPORTS_INVALIDATE
     .bdrv_invalidate_cache  = qemu_rbd_invalidate_cache,
 #endif
+
+    .sgfnt_runtime_opts     = (const char *const[]) { "password-secret", NULL },
 };
 
 static void bdrv_rbd_init(void)
diff --git a/block/vvfat.c b/block/vvfat.c
index ded21092ee..94f28606c7 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -3077,6 +3077,10 @@ static BlockDriver bdrv_vvfat = {
     .bdrv_co_preadv         = vvfat_co_preadv,
     .bdrv_co_pwritev        = vvfat_co_pwritev,
     .bdrv_co_get_block_status = vvfat_co_get_block_status,
+
+    .sgfnt_runtime_opts     = (const char *const[]) { "dir", "fat-type",
+                                                      "floppy", "label", "rw",
+                                                      NULL },
 };
 
 static void bdrv_vvfat_init(void)
-- 
2.11.0

[Qemu-devel] [PATCH v4 19/25] block: Add BlockDriver.bdrv_gather_child_options

[Max Reitz]

Some follow-up patches will rework the way bs->full_open_options is
refreshed in bdrv_refresh_filename(). The new implementation will remove
the need for the block drivers' bdrv_refresh_filename() implementations
to set bs->full_open_options; instead, it will be generic and use static
information from each block driver.

However, by implementing bdrv_gather_child_options(), block drivers will
still be able to override the way the full_open_options of their
children are incorporated into their own.

We need to implement this function for VMDK because we have to prevent
the generic implementation from gathering the options of all children:
It is not possible to specify options for the extents through the
runtime options.

For quorum, the child names that would be used by the generic
implementation and the ones that we actually want to use differ. See
quorum_gather_child_options() for more information.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 include/block/block_int.h |  1 +
 block/quorum.c            | 30 ++++++++++++++++++++++++++++++
 block/vmdk.c              | 13 +++++++++++++
 3 files changed, 44 insertions(+)

diff --git a/include/block/block_int.h b/include/block/block_int.h
index 799c892558..77f4121358 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -130,6 +130,7 @@ struct BlockDriver {
     int (*bdrv_make_empty)(BlockDriverState *bs);
 
     void (*bdrv_refresh_filename)(BlockDriverState *bs, QDict *options);
+    void (*bdrv_gather_child_options)(BlockDriverState *bs, QDict *target);
     char *(*bdrv_dirname)(BlockDriverState *bs, Error **errp);
 
     /* aio */
diff --git a/block/quorum.c b/block/quorum.c
index 878b8cfa9a..0a77ed44fd 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1105,6 +1105,35 @@ static void quorum_refresh_filename(BlockDriverState *bs, QDict *options)
     bs->full_open_options = opts;
 }
 
+static void quorum_gather_child_options(BlockDriverState *bs, QDict *target)
+{
+    BDRVQuorumState *s = bs->opaque;
+    QList *children_list;
+    int i;
+
+    /* The generic implementation for gathering child options in
+     * bdrv_refresh_filename() would use the names of the children as specified
+     * for bdrv_open_child() or bdrv_attach_child(), which is "children.%u" with
+     * %u being a value (s->next_child_index) that is incremented each time a
+     * new child is added (and never decremented). Since children can be deleted
+     * at runtime, there may be gaps in that enumeration. When creating a new
+     * quorum BDS and specifying the children for it through runtime options,
+     * the enumeration used there may not have any gaps, though.
+     *
+     * Therefore, we have to create a new gap-less enumeration here (which we
+     * can achieve by simply putting all of the children's full_open_options
+     * into a QList).
+     */
+
+    children_list = qlist_new();
+    qdict_put(target, "children", children_list);
+
+    for (i = 0; i < s->num_children; i++) {
+        QINCREF(s->children[i]->bs->full_open_options);
+        qlist_append(children_list, s->children[i]->bs->full_open_options);
+    }
+}
+
 static char *quorum_dirname(BlockDriverState *bs, Error **errp)
 {
     /* In general, there are multiple BDSs with different dirnames below this
@@ -1124,6 +1153,7 @@ static BlockDriver bdrv_quorum = {
     .bdrv_file_open                     = quorum_open,
     .bdrv_close                         = quorum_close,
     .bdrv_refresh_filename              = quorum_refresh_filename,
+    .bdrv_gather_child_options          = quorum_gather_child_options,
     .bdrv_dirname                       = quorum_dirname,
 
     .bdrv_co_flush_to_disk              = quorum_co_flush,
diff --git a/block/vmdk.c b/block/vmdk.c
index 6f6932aa3f..87ac4f0e68 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -2287,6 +2287,18 @@ static int vmdk_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
     return 0;
 }
 
+static void vmdk_gather_child_options(BlockDriverState *bs, QDict *target)
+{
+    /* No children but file and backing can be explicitly specified */
+    QINCREF(bs->file->bs->full_open_options);
+    qdict_put(target, "file", bs->file->bs->full_open_options);
+
+    if (bs->backing_overridden) {
+        QINCREF(bs->backing->bs->full_open_options);
+        qdict_put(target, "backing", bs->backing->bs->full_open_options);
+    }
+}
+
 static QemuOptsList vmdk_create_opts = {
     .name = "vmdk-create-opts",
     .head = QTAILQ_HEAD_INITIALIZER(vmdk_create_opts.head),
@@ -2356,6 +2368,7 @@ static BlockDriver bdrv_vmdk = {
     .bdrv_get_specific_info       = vmdk_get_specific_info,
     .bdrv_refresh_limits          = vmdk_refresh_limits,
     .bdrv_get_info                = vmdk_get_info,
+    .bdrv_gather_child_options    = vmdk_gather_child_options,
 
     .supports_backing             = true,
     .create_opts                  = &vmdk_create_opts,
-- 
2.11.0

[Qemu-devel] [PATCH v4 20/25] block: Generically refresh runtime options

[Max Reitz]

Instead of having every block driver which implements
bdrv_refresh_filename() copy all of the significant runtime options over
to bs->full_open_options, implement this process generically in
bdrv_refresh_filename().

This patch only adds this new generic implementation, it does not remove
the old functionality. This is done in a follow-up patch.

With this patch, some superfluous information (that should never have
been there) may be removed from some JSON filenames, as can be seen in
the change to iotest 110's reference output.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c                    | 116 ++++++++++++++++++++++++++++++++++++++++++++-
 tests/qemu-iotests/110.out |   4 +-
 2 files changed, 117 insertions(+), 3 deletions(-)

diff --git a/block.c b/block.c
index a10ba111bc..a87eb631bc 100644
--- a/block.c
+++ b/block.c
@@ -3935,6 +3935,92 @@ out:
     return to_replace_bs;
 }
 
+/**
+ * Iterates through the list of runtime option keys that are said to be
+ * "significant" for a BDS. An option is called "significant" if it changes a
+ * BDS's data. For example, the null block driver's "size" and "read-zeroes"
+ * options are significant, but its "latency-ns" option is not.
+ *
+ * If a key returned by this function ends with a dot, all options starting with
+ * that prefix are significant.
+ */
+static const char *const *significant_options(BlockDriverState *bs,
+                                              const char *const *curopt)
+{
+    static const char *const global_options[] = {
+        "driver", "filename", "base-directory", NULL
+    };
+
+    if (!curopt) {
+        return &global_options[0];
+    }
+
+    curopt++;
+    if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) {
+        curopt = bs->drv->sgfnt_runtime_opts;
+    }
+
+    return (curopt && *curopt) ? curopt : NULL;
+}
+
+/**
+ * Copies all significant runtime options from bs->options to the given QDict.
+ * The set of significant option keys is determined by invoking
+ * significant_options().
+ *
+ * Returns true iff any significant option was present in bs->options (and thus
+ * copied to the target QDict) with the exception of "filename" and "driver".
+ * The caller is expected to use this value to decide whether the existence of
+ * significant options prevents the generation of a plain filename.
+ */
+static bool append_significant_runtime_options(QDict *d, BlockDriverState *bs)
+{
+    bool found_any = false;
+    const char *const *option_name = NULL;
+
+    if (!bs->drv) {
+        return false;
+    }
+
+    while ((option_name = significant_options(bs, option_name))) {
+        bool option_given = false;
+
+        assert(strlen(*option_name) > 0);
+        if ((*option_name)[strlen(*option_name) - 1] != '.') {
+            QObject *entry = qdict_get(bs->options, *option_name);
+            if (!entry) {
+                continue;
+            }
+
+            qobject_incref(entry);
+            qdict_put_obj(d, *option_name, entry);
+            option_given = true;
+        } else {
+            const QDictEntry *entry;
+            for (entry = qdict_first(bs->options); entry;
+                 entry = qdict_next(bs->options, entry))
+            {
+                if (strstart(qdict_entry_key(entry), *option_name, NULL)) {
+                    qobject_incref(qdict_entry_value(entry));
+                    qdict_put_obj(d, qdict_entry_key(entry),
+                                  qdict_entry_value(entry));
+                    option_given = true;
+                }
+            }
+        }
+
+        /* While "driver" and "filename" need to be included in a JSON filename,
+         * their existence does not prohibit generation of a plain filename. */
+        if (!found_any && option_given &&
+            strcmp(*option_name, "driver") && strcmp(*option_name, "filename"))
+        {
+            found_any = true;
+        }
+    }
+
+    return found_any;
+}
+
 static bool append_open_options(QDict *d, BlockDriverState *bs)
 {
     const QDictEntry *entry;
@@ -4093,9 +4179,37 @@ void bdrv_refresh_filename(BlockDriverState *bs)
         bs->full_open_options = opts;
     }
 
+    /* Gather the options QDict */
+    opts = qdict_new();
+    append_significant_runtime_options(opts, bs);
+
+    if (drv->bdrv_gather_child_options) {
+        /* Some block drivers may not want to present all of their children's
+         * options, or name them differently from BdrvChild.name */
+        drv->bdrv_gather_child_options(bs, opts);
+    } else {
+        QLIST_FOREACH(child, &bs->children, next) {
+            if (child->role == &child_backing && !bs->backing_overridden) {
+                /* We can skip the backing BDS if it has not been overridden */
+                continue;
+            }
+
+            QINCREF(child->bs->full_open_options);
+            qdict_put(opts, child->name, child->bs->full_open_options);
+        }
+
+        if (bs->backing_overridden && !bs->backing) {
+            /* Force no backing file */
+            qdict_put(opts, "backing", qstring_new());
+        }
+    }
+
+    QDECREF(bs->full_open_options);
+    bs->full_open_options = opts;
+
     if (bs->exact_filename[0]) {
         pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename);
-    } else if (bs->full_open_options) {
+    } else {
         QString *json = qobject_to_json(QOBJECT(bs->full_open_options));
         snprintf(bs->filename, sizeof(bs->filename), "json:%s",
                  qstring_get_str(json));
diff --git a/tests/qemu-iotests/110.out b/tests/qemu-iotests/110.out
index e1845d8026..7eb199dd5c 100644
--- a/tests/qemu-iotests/110.out
+++ b/tests/qemu-iotests/110.out
@@ -22,12 +22,12 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=t.IMGFMT.b
 
 === Nodes without a common directory ===
 
-image: json:{"driver": "IMGFMT", "file": {"children": [{"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.copy"}], "driver": "quorum", "blkverify": false, "rewrite-corrupted": false, "vote-threshold": 1}}
+image: json:{"driver": "IMGFMT", "file": {"children": [{"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.copy"}], "driver": "quorum", "vote-threshold": 1}}
 file format: IMGFMT
 virtual size: 64M (67108864 bytes)
 backing file: t.IMGFMT.base (cannot determine actual path)
 
-image: json:{"driver": "IMGFMT", "file": {"children": [{"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.copy"}], "driver": "quorum", "blkverify": false, "rewrite-corrupted": false, "vote-threshold": 1}}
+image: json:{"driver": "IMGFMT", "file": {"children": [{"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}, {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.copy"}], "driver": "quorum", "base-directory": "TEST_DIR/", "vote-threshold": 1}}
 file format: IMGFMT
 virtual size: 64M (67108864 bytes)
 backing file: t.IMGFMT.base (actual path: TEST_DIR/t.IMGFMT.base)
-- 
2.11.0

[Qemu-devel] [PATCH v4 21/25] block: Purify .bdrv_refresh_filename()

[Max Reitz]

Currently, BlockDriver.bdrv_refresh_filename() is supposed to both
refresh the filename (BDS.exact_filename) and set BDS.full_open_options.
Now that we have generic code in the central bdrv_refresh_filename() for
creating BDS.full_open_options, we can drop the latter part from all
BlockDriver.bdrv_refresh_filename() implementations.

This also means that we can drop all of the existing default code for
this from the global bdrv_refresh_filename() itself.

Furthermore, we now have to call BlockDriver.bdrv_refresh_filename()
after having set BDS.full_open_options, because the block driver's
implementation should now be allowed to depend on BDS.full_open_options
being set correctly.

Finally, with this patch we can drop the @options parameter from
BlockDriver.bdrv_refresh_filename().

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 include/block/block_int.h |   2 +-
 block.c                   | 149 +++++++---------------------------------------
 block/blkdebug.c          |  44 ++++----------
 block/blkverify.c         |  17 +-----
 block/nbd.c               |  25 +-------
 block/nfs.c               |  41 +------------
 block/null.c              |  23 ++++---
 block/quorum.c            |  34 -----------
 8 files changed, 52 insertions(+), 283 deletions(-)

diff --git a/include/block/block_int.h b/include/block/block_int.h
index 77f4121358..eba463b99b 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -129,7 +129,7 @@ struct BlockDriver {
     int (*bdrv_set_key)(BlockDriverState *bs, const char *key);
     int (*bdrv_make_empty)(BlockDriverState *bs);
 
-    void (*bdrv_refresh_filename)(BlockDriverState *bs, QDict *options);
+    void (*bdrv_refresh_filename)(BlockDriverState *bs);
     void (*bdrv_gather_child_options)(BlockDriverState *bs, QDict *target);
     char *(*bdrv_dirname)(BlockDriverState *bs, Error **errp);
 
diff --git a/block.c b/block.c
index a87eb631bc..be811457ed 100644
--- a/block.c
+++ b/block.c
@@ -4021,47 +4021,6 @@ static bool append_significant_runtime_options(QDict *d, BlockDriverState *bs)
     return found_any;
 }
 
-static bool append_open_options(QDict *d, BlockDriverState *bs)
-{
-    const QDictEntry *entry;
-    QemuOptDesc *desc;
-    BdrvChild *child;
-    bool found_any = false;
-    const char *p;
-
-    for (entry = qdict_first(bs->options); entry;
-         entry = qdict_next(bs->options, entry))
-    {
-        /* Exclude options for children */
-        QLIST_FOREACH(child, &bs->children, next) {
-            if (strstart(qdict_entry_key(entry), child->name, &p)
-                && (!*p || *p == '.'))
-            {
-                break;
-            }
-        }
-        if (child) {
-            continue;
-        }
-
-        /* And exclude all non-driver-specific options */
-        for (desc = bdrv_runtime_opts.desc; desc->name; desc++) {
-            if (!strcmp(qdict_entry_key(entry), desc->name)) {
-                break;
-            }
-        }
-        if (desc->name) {
-            continue;
-        }
-
-        qobject_incref(qdict_entry_value(entry));
-        qdict_put_obj(d, qdict_entry_key(entry), qdict_entry_value(entry));
-        found_any = true;
-    }
-
-    return found_any;
-}
-
 /* Updates the following BDS fields:
  *  - exact_filename: A filename which may be used for opening a block device
  *                    which (mostly) equals the given BDS (even without any
@@ -4079,6 +4038,8 @@ void bdrv_refresh_filename(BlockDriverState *bs)
     BlockDriver *drv = bs->drv;
     BdrvChild *child;
     QDict *opts;
+    bool generate_json_filename; /* Whether our default implementation should
+                                    fill exact_filename (false) or not (true) */
 
     if (!drv) {
         return;
@@ -4094,94 +4055,10 @@ void bdrv_refresh_filename(BlockDriverState *bs)
         }
     }
 
-    if (drv->bdrv_refresh_filename) {
-        /* Obsolete information is of no use here, so drop the old file name
-         * information before refreshing it */
-        bs->exact_filename[0] = '\0';
-        if (bs->full_open_options) {
-            QDECREF(bs->full_open_options);
-            bs->full_open_options = NULL;
-        }
-
-        opts = qdict_new();
-        append_open_options(opts, bs);
-        drv->bdrv_refresh_filename(bs, opts);
-        QDECREF(opts);
-    } else if (bs->file) {
-        /* Try to reconstruct valid information from the underlying file */
-        bool has_open_options;
-
-        bs->exact_filename[0] = '\0';
-        if (bs->full_open_options) {
-            QDECREF(bs->full_open_options);
-            bs->full_open_options = NULL;
-        }
-
-        opts = qdict_new();
-        has_open_options = append_open_options(opts, bs);
-        has_open_options |= bs->backing_overridden;
-
-        /* If no specific options have been given for this BDS, the filename of
-         * the underlying file should suffice for this one as well */
-        if (bs->file->bs->exact_filename[0] && !has_open_options) {
-            strcpy(bs->exact_filename, bs->file->bs->exact_filename);
-        }
-        /* Reconstructing the full options QDict is simple for most format block
-         * drivers, as long as the full options are known for the underlying
-         * file BDS. The full options QDict of that file BDS should somehow
-         * contain a representation of the filename, therefore the following
-         * suffices without querying the (exact_)filename of this BDS. */
-        if (bs->file->bs->full_open_options &&
-            (!bs->backing || bs->backing->bs->full_open_options))
-        {
-            qdict_put_obj(opts, "driver",
-                          QOBJECT(qstring_from_str(drv->format_name)));
-            QINCREF(bs->file->bs->full_open_options);
-            qdict_put_obj(opts, "file",
-                          QOBJECT(bs->file->bs->full_open_options));
-
-            if (bs->backing) {
-                QINCREF(bs->backing->bs->full_open_options);
-                qdict_put(opts, "backing", bs->backing->bs->full_open_options);
-            } else if (bs->backing_overridden && !bs->backing) {
-                qdict_put(opts, "backing", qstring_new());
-            }
-
-            bs->full_open_options = opts;
-        } else {
-            QDECREF(opts);
-        }
-    } else if (!bs->full_open_options && qdict_size(bs->options)) {
-        /* There is no underlying file BDS (at least referenced by BDS.file),
-         * so the full options QDict should be equal to the options given
-         * specifically for this block device when it was opened (plus the
-         * driver specification).
-         * Because those options don't change, there is no need to update
-         * full_open_options when it's already set. */
-
-        opts = qdict_new();
-        append_open_options(opts, bs);
-        qdict_put_obj(opts, "driver",
-                      QOBJECT(qstring_from_str(drv->format_name)));
-
-        if (bs->exact_filename[0]) {
-            /* This may not work for all block protocol drivers (some may
-             * require this filename to be parsed), but we have to find some
-             * default solution here, so just include it. If some block driver
-             * does not support pure options without any filename at all or
-             * needs some special format of the options QDict, it needs to
-             * implement the driver-specific bdrv_refresh_filename() function.
-             */
-            qdict_put_obj(opts, "filename",
-                          QOBJECT(qstring_from_str(bs->exact_filename)));
-        }
-
-        bs->full_open_options = opts;
-    }
-
     /* Gather the options QDict */
     opts = qdict_new();
-    append_significant_runtime_options(opts, bs);
+    generate_json_filename = append_significant_runtime_options(opts, bs);
+    generate_json_filename |= bs->backing_overridden;
 
     if (drv->bdrv_gather_child_options) {
         /* Some block drivers may not want to present all of their children's
@@ -4207,6 +4084,24 @@ void bdrv_refresh_filename(BlockDriverState *bs)
     QDECREF(bs->full_open_options);
     bs->full_open_options = opts;
 
+    if (drv->bdrv_refresh_filename) {
+        /* Obsolete information is of no use here, so drop the old file name
+         * information before refreshing it */
+        bs->exact_filename[0] = '\0';
+
+        drv->bdrv_refresh_filename(bs);
+    } else if (bs->file) {
+        /* Try to reconstruct valid information from the underlying file */
+
+        bs->exact_filename[0] = '\0';
+
+        /* If no specific options have been given for this BDS, the filename of
+         * the underlying file should suffice for this one as well */
+        if (bs->file->bs->exact_filename[0] && !generate_json_filename) {
+            strcpy(bs->exact_filename, bs->file->bs->exact_filename);
+        }
+    }
+
     if (bs->exact_filename[0]) {
         pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename);
     } else {
diff --git a/block/blkdebug.c b/block/blkdebug.c
index 1551b2099a..6b33f316f9 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -673,48 +673,28 @@ static int blkdebug_truncate(BlockDriverState *bs, int64_t offset)
     return bdrv_truncate(bs->file->bs, offset);
 }
 
-static void blkdebug_refresh_filename(BlockDriverState *bs, QDict *options)
+static void blkdebug_refresh_filename(BlockDriverState *bs)
 {
     BDRVBlkdebugState *s = bs->opaque;
-    QDict *opts;
     const QDictEntry *e;
-    bool force_json = false;
 
-    for (e = qdict_first(options); e; e = qdict_next(options, e)) {
-        if (strcmp(qdict_entry_key(e), "config") &&
-            strcmp(qdict_entry_key(e), "x-image"))
-        {
-            force_json = true;
-            break;
-        }
-    }
-
-    if (force_json && !bs->file->bs->full_open_options) {
-        /* The config file cannot be recreated, so creating a plain filename
-         * is impossible */
+    if (!bs->file->bs->exact_filename[0]) {
         return;
     }
 
-    if (!force_json && bs->file->bs->exact_filename[0]) {
-        snprintf(bs->exact_filename, sizeof(bs->exact_filename),
-                 "blkdebug:%s:%s", s->config_file ?: "",
-                 bs->file->bs->exact_filename);
-    }
-
-    opts = qdict_new();
-    qdict_put_obj(opts, "driver", QOBJECT(qstring_from_str("blkdebug")));
-
-    QINCREF(bs->file->bs->full_open_options);
-    qdict_put_obj(opts, "image", QOBJECT(bs->file->bs->full_open_options));
-
-    for (e = qdict_first(options); e; e = qdict_next(options, e)) {
-        if (strcmp(qdict_entry_key(e), "x-image")) {
-            qobject_incref(qdict_entry_value(e));
-            qdict_put_obj(opts, qdict_entry_key(e), qdict_entry_value(e));
+    for (e = qdict_first(bs->full_open_options); e;
+         e = qdict_next(bs->full_open_options, e))
+    {
+        if (strcmp(qdict_entry_key(e), "config") &&
+            strcmp(qdict_entry_key(e), "image") &&
+            strcmp(qdict_entry_key(e), "driver"))
+        {
+            return;
         }
     }
 
-    bs->full_open_options = opts;
+    snprintf(bs->exact_filename, sizeof(bs->exact_filename), "blkdebug:%s:%s",
+             s->config_file ?: "", bs->file->bs->exact_filename);
 }
 
 static void blkdebug_refresh_limits(BlockDriverState *bs, Error **errp)
diff --git a/block/blkverify.c b/block/blkverify.c
index c72a1fba64..9c58758740 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -280,25 +280,10 @@ static bool blkverify_recurse_is_first_non_filter(BlockDriverState *bs,
     return bdrv_recurse_is_first_non_filter(s->test_file->bs, candidate);
 }
 
-static void blkverify_refresh_filename(BlockDriverState *bs, QDict *options)
+static void blkverify_refresh_filename(BlockDriverState *bs)
 {
     BDRVBlkverifyState *s = bs->opaque;
 
-    if (bs->file->bs->full_open_options
-        && s->test_file->bs->full_open_options)
-    {
-        QDict *opts = qdict_new();
-        qdict_put_obj(opts, "driver", QOBJECT(qstring_from_str("blkverify")));
-
-        QINCREF(bs->file->bs->full_open_options);
-        qdict_put_obj(opts, "raw", QOBJECT(bs->file->bs->full_open_options));
-        QINCREF(s->test_file->bs->full_open_options);
-        qdict_put_obj(opts, "test",
-                      QOBJECT(s->test_file->bs->full_open_options));
-
-        bs->full_open_options = opts;
-    }
-
     if (bs->file->bs->exact_filename[0]
         && s->test_file->bs->exact_filename[0])
     {
diff --git a/block/nbd.c b/block/nbd.c
index 130798903f..ea5d7a819e 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -499,12 +499,9 @@ static void nbd_attach_aio_context(BlockDriverState *bs,
     nbd_client_attach_aio_context(bs, new_context);
 }
 
-static void nbd_refresh_filename(BlockDriverState *bs, QDict *options)
+static void nbd_refresh_filename(BlockDriverState *bs)
 {
     BDRVNBDState *s = bs->opaque;
-    QDict *opts = qdict_new();
-    QObject *saddr_qdict;
-    Visitor *ov;
     const char *host = NULL, *port = NULL, *path = NULL;
 
     if (s->saddr->type == SOCKET_ADDRESS_KIND_INET) {
@@ -517,8 +514,6 @@ static void nbd_refresh_filename(BlockDriverState *bs, QDict *options)
         path = s->saddr->u.q_unix.data->path;
     }
 
-    qdict_put(opts, "driver", qstring_from_str("nbd"));
-
     if (path && s->export) {
         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
                  "nbd+unix:///%s?socket=%s", s->export, path);
@@ -532,24 +527,6 @@ static void nbd_refresh_filename(BlockDriverState *bs, QDict *options)
         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
                  "nbd://%s:%s", host, port);
     }
-
-    ov = qobject_output_visitor_new(&saddr_qdict);
-    visit_type_SocketAddress(ov, NULL, &s->saddr, &error_abort);
-    visit_complete(ov, &saddr_qdict);
-    visit_free(ov);
-    assert(qobject_type(saddr_qdict) == QTYPE_QDICT);
-
-    qdict_put_obj(opts, "server", saddr_qdict);
-
-    if (s->export) {
-        qdict_put(opts, "export", qstring_from_str(s->export));
-    }
-    if (s->tlscredsid) {
-        qdict_put(opts, "tls-creds", qstring_from_str(s->tlscredsid));
-    }
-
-    qdict_flatten(opts);
-    bs->full_open_options = opts;
 }
 
 static char *nbd_dirname(BlockDriverState *bs, Error **errp)
diff --git a/block/nfs.c b/block/nfs.c
index d4ca2757a1..6e68c27437 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -768,14 +768,9 @@ static int nfs_reopen_prepare(BDRVReopenState *state,
     return 0;
 }
 
-static void nfs_refresh_filename(BlockDriverState *bs, QDict *options)
+static void nfs_refresh_filename(BlockDriverState *bs)
 {
     NFSClient *client = bs->opaque;
-    QDict *opts = qdict_new();
-    QObject *server_qdict;
-    Visitor *ov;
-
-    qdict_put(opts, "driver", qstring_from_str("nfs"));
 
     if (client->uid && !client->gid) {
         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
@@ -793,40 +788,6 @@ static void nfs_refresh_filename(BlockDriverState *bs, QDict *options)
         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
                  "nfs://%s%s", client->server->host, client->path);
     }
-
-    ov = qobject_output_visitor_new(&server_qdict);
-    visit_type_NFSServer(ov, NULL, &client->server, &error_abort);
-    visit_complete(ov, &server_qdict);
-    assert(qobject_type(server_qdict) == QTYPE_QDICT);
-
-    qdict_put_obj(opts, "server", server_qdict);
-    qdict_put(opts, "path", qstring_from_str(client->path));
-
-    if (client->uid) {
-        qdict_put(opts, "uid", qint_from_int(client->uid));
-    }
-    if (client->gid) {
-        qdict_put(opts, "gid", qint_from_int(client->gid));
-    }
-    if (client->tcp_syncnt) {
-        qdict_put(opts, "tcp-syncnt",
-                      qint_from_int(client->tcp_syncnt));
-    }
-    if (client->readahead) {
-        qdict_put(opts, "readahead",
-                      qint_from_int(client->readahead));
-    }
-    if (client->pagecache) {
-        qdict_put(opts, "pagecache",
-                      qint_from_int(client->pagecache));
-    }
-    if (client->debug) {
-        qdict_put(opts, "debug", qint_from_int(client->debug));
-    }
-
-    visit_free(ov);
-    qdict_flatten(opts);
-    bs->full_open_options = opts;
 }
 
 static char *nfs_dirname(BlockDriverState *bs, Error **errp)
diff --git a/block/null.c b/block/null.c
index 16ef8b2a09..fb03fb95c0 100644
--- a/block/null.c
+++ b/block/null.c
@@ -222,18 +222,23 @@ static int64_t coroutine_fn null_co_get_block_status(BlockDriverState *bs,
     }
 }
 
-static void null_refresh_filename(BlockDriverState *bs, QDict *opts)
+static void null_refresh_filename(BlockDriverState *bs)
 {
-    QINCREF(opts);
-    qdict_del(opts, "filename");
-
-    if (!qdict_size(opts)) {
-        snprintf(bs->exact_filename, sizeof(bs->exact_filename), "%s://",
-                 bs->drv->format_name);
+    const QDictEntry *e;
+
+    for (e = qdict_first(bs->full_open_options); e;
+         e = qdict_next(bs->full_open_options, e))
+    {
+        /* These options can be ignored */
+        if (strcmp(qdict_entry_key(e), "filename") &&
+            strcmp(qdict_entry_key(e), "driver"))
+        {
+            return;
+        }
     }
 
-    qdict_put(opts, "driver", qstring_from_str(bs->drv->format_name));
-    bs->full_open_options = opts;
+    snprintf(bs->exact_filename, sizeof(bs->exact_filename), "%s://",
+             bs->drv->format_name);
 }
 
 static const char *const null_sgfnt_runtime_opts[] = {
diff --git a/block/quorum.c b/block/quorum.c
index 0a77ed44fd..422185b845 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1072,39 +1072,6 @@ static void quorum_del_child(BlockDriverState *bs, BdrvChild *child,
     bdrv_drained_end(bs);
 }
 
-static void quorum_refresh_filename(BlockDriverState *bs, QDict *options)
-{
-    BDRVQuorumState *s = bs->opaque;
-    QDict *opts;
-    QList *children;
-    int i;
-
-    for (i = 0; i < s->num_children; i++) {
-        if (!s->children[i]->bs->full_open_options) {
-            return;
-        }
-    }
-
-    children = qlist_new();
-    for (i = 0; i < s->num_children; i++) {
-        QINCREF(s->children[i]->bs->full_open_options);
-        qlist_append_obj(children,
-                         QOBJECT(s->children[i]->bs->full_open_options));
-    }
-
-    opts = qdict_new();
-    qdict_put_obj(opts, "driver", QOBJECT(qstring_from_str("quorum")));
-    qdict_put_obj(opts, QUORUM_OPT_VOTE_THRESHOLD,
-                  QOBJECT(qint_from_int(s->threshold)));
-    qdict_put_obj(opts, QUORUM_OPT_BLKVERIFY,
-                  QOBJECT(qbool_from_bool(s->is_blkverify)));
-    qdict_put_obj(opts, QUORUM_OPT_REWRITE,
-                  QOBJECT(qbool_from_bool(s->rewrite_corrupted)));
-    qdict_put_obj(opts, "children", QOBJECT(children));
-
-    bs->full_open_options = opts;
-}
-
 static void quorum_gather_child_options(BlockDriverState *bs, QDict *target)
 {
     BDRVQuorumState *s = bs->opaque;
@@ -1152,7 +1119,6 @@ static BlockDriver bdrv_quorum = {
 
     .bdrv_file_open                     = quorum_open,
     .bdrv_close                         = quorum_close,
-    .bdrv_refresh_filename              = quorum_refresh_filename,
     .bdrv_gather_child_options          = quorum_gather_child_options,
     .bdrv_dirname                       = quorum_dirname,
 
-- 
2.11.0

[Qemu-devel] [PATCH v4 22/25] block: Do not copy exact_filename from format file

[Max Reitz]

If the a format BDS's file BDS is in turn a format BDS, we cannot simply
use the same filename, because when opening a BDS tree based on a
filename alone, qemu will create only one format node on top of one
protocol node (disregarding a potential backing file).

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/block.c b/block.c
index be811457ed..3a2085b631 100644
--- a/block.c
+++ b/block.c
@@ -4095,9 +4095,20 @@ void bdrv_refresh_filename(BlockDriverState *bs)
 
         bs->exact_filename[0] = '\0';
 
-        /* If no specific options have been given for this BDS, the filename of
-         * the underlying file should suffice for this one as well */
-        if (bs->file->bs->exact_filename[0] && !generate_json_filename) {
+        /* We can use the underlying file's filename if:
+         * - it has a filename,
+         * - the file is a protocol BDS, and
+         * - opening that file (as this BDS's format) will automatically create
+         *   the BDS tree we have right now, that is:
+         *   - the user did not significantly change this BDS's behavior with
+         *     some explicit options
+         *   - no non-file child of this BDS has been overridden by the user
+         *   Both of these conditions are represented by generate_json_filename.
+         */
+        if (bs->file->bs->exact_filename[0] &&
+            bs->file->bs->drv->bdrv_file_open &&
+            !generate_json_filename)
+        {
             strcpy(bs->exact_filename, bs->file->bs->exact_filename);
         }
     }
-- 
2.11.0

[Qemu-devel] [PATCH v4 23/25] block: Fix FIXME from "Add BDS.backing_overridden"

[Max Reitz]

Said commit introduced a FIXME stating that bdrv_open_backing_file()
should set bs->backing_overridden to true not only if the file.filename
option was set, but if the "options" QDict contained any option that is
significant for any node in the BDS tree emerging from the backing BDS.
This behavior is implemented by this patch.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 75 insertions(+), 6 deletions(-)

diff --git a/block.c b/block.c
index 3a2085b631..c63fc1b2da 100644
--- a/block.c
+++ b/block.c
@@ -74,6 +74,9 @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
                                            const BdrvChildRole *child_role,
                                            Error **errp);
 
+static bool has_significant_runtime_options(BlockDriverState *bs,
+                                            const QDict *d);
+
 /* If non-zero, use only whitelisted block drivers */
 static int use_bdrv_whitelist;
 
@@ -1481,6 +1484,42 @@ out:
     bdrv_refresh_limits(bs, NULL);
 }
 
+/**
+ * Checks whether @options contains any significant option for any of the nodes
+ * in the BDS tree emerging from @bs.
+ */
+static bool is_significant_option_tree(BlockDriverState *bs, QDict *options)
+{
+    BdrvChild *child;
+
+    if (!qdict_size(options)) {
+        /* No need to recurse */
+        return false;
+    }
+
+    if (has_significant_runtime_options(bs, options)) {
+        return true;
+    }
+
+    QLIST_FOREACH(child, &bs->children, next) {
+        QDict *child_options;
+        char *option_prefix;
+
+        option_prefix = g_strdup_printf("%s.", child->name);
+        qdict_extract_subqdict(options, &child_options, option_prefix);
+        g_free(option_prefix);
+
+        if (is_significant_option_tree(child->bs, child_options)) {
+            QDECREF(child_options);
+            return true;
+        }
+
+        QDECREF(child_options);
+    }
+
+    return false;
+}
+
 /*
  * Opens the backing file for a BlockDriverState if not yet open
  *
@@ -1499,7 +1538,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
     const char *reference = NULL;
     int ret = 0;
     BlockDriverState *backing_hd;
-    QDict *options;
+    QDict *options, *cloned_options = NULL;
     QDict *tmp_parent_options = NULL;
     Error *local_err = NULL;
 
@@ -1522,11 +1561,6 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
     reference = qdict_get_try_str(parent_options, bdref_key);
     if (reference || qdict_haskey(options, "file.filename")) {
         /* keep backing_filename NULL */
-
-        /* FIXME: Should also be set to true if @options contains other runtime
-         *        options which control the data that is read from the backing
-         *        BDS */
-        bs->backing_overridden = true;
     } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
         QDECREF(options);
         goto free_exit;
@@ -1547,6 +1581,8 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
         goto free_exit;
     }
 
+    cloned_options = qdict_clone_shallow(options);
+
     if (bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {
         qdict_put(options, "driver", qstring_from_str(bs->backing_format));
     }
@@ -1560,6 +1596,10 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
         goto free_exit;
     }
 
+    if (reference || is_significant_option_tree(backing_hd, cloned_options)) {
+        bs->backing_overridden = true;
+    }
+
     /* Hook up the backing file link; drop our reference, bs owns the
      * backing_hd reference now */
     bdrv_set_backing_hd(bs, backing_hd);
@@ -1570,6 +1610,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
 free_exit:
     g_free(backing_filename);
     QDECREF(tmp_parent_options);
+    QDECREF(cloned_options);
     return ret;
 }
 
@@ -3964,6 +4005,34 @@ static const char *const *significant_options(BlockDriverState *bs,
 }
 
 /**
+ * Returns true if @d contains any options the block driver of @bs considers to
+ * be significant runtime options.
+ */
+static bool has_significant_runtime_options(BlockDriverState *bs,
+                                            const QDict *d)
+{
+    const char *const *option_name = NULL;
+
+    while ((option_name = significant_options(bs, option_name))) {
+        assert(strlen(*option_name) > 0);
+        if ((*option_name)[strlen(*option_name) - 1] != '.') {
+            if (qdict_haskey(d, *option_name)) {
+                return true;
+            }
+        } else {
+            const QDictEntry *entry;
+            for (entry = qdict_first(d); entry; entry = qdict_next(d, entry)) {
+                if (strstart(qdict_entry_key(entry), *option_name, NULL)) {
+                    return true;
+                }
+            }
+        }
+    }
+
+    return false;
+}
+
+/**
  * Copies all significant runtime options from bs->options to the given QDict.
  * The set of significant option keys is determined by invoking
  * significant_options().
-- 
2.11.0

[Qemu-devel] [PATCH v4 24/25] block/curl: Implement bdrv_refresh_filename()

[Max Reitz]

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/curl.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/block/curl.c b/block/curl.c
index 34a5b0f7e3..7f129a35df 100644
--- a/block/curl.c
+++ b/block/curl.c
@@ -872,6 +872,20 @@ static int64_t curl_getlength(BlockDriverState *bs)
     return s->len;
 }
 
+static void curl_refresh_filename(BlockDriverState *bs)
+{
+    BDRVCURLState *s = bs->opaque;
+
+    if (!s->sslverify || s->cookie ||
+        s->username || s->password || s->proxyusername || s->proxypassword)
+    {
+        return;
+    }
+
+    pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), s->url);
+}
+
+
 static const char *const curl_sgfnt_runtime_opts[] = {
     CURL_BLOCK_OPT_URL,
     CURL_BLOCK_OPT_SSLVERIFY,
@@ -899,6 +913,7 @@ static BlockDriver bdrv_http = {
     .bdrv_detach_aio_context    = curl_detach_aio_context,
     .bdrv_attach_aio_context    = curl_attach_aio_context,
 
+    .bdrv_refresh_filename      = curl_refresh_filename,
     .sgfnt_runtime_opts         = curl_sgfnt_runtime_opts,
 };
 
@@ -917,6 +932,7 @@ static BlockDriver bdrv_https = {
     .bdrv_detach_aio_context    = curl_detach_aio_context,
     .bdrv_attach_aio_context    = curl_attach_aio_context,
 
+    .bdrv_refresh_filename      = curl_refresh_filename,
     .sgfnt_runtime_opts         = curl_sgfnt_runtime_opts,
 };
 
@@ -935,6 +951,7 @@ static BlockDriver bdrv_ftp = {
     .bdrv_detach_aio_context    = curl_detach_aio_context,
     .bdrv_attach_aio_context    = curl_attach_aio_context,
 
+    .bdrv_refresh_filename      = curl_refresh_filename,
     .sgfnt_runtime_opts         = curl_sgfnt_runtime_opts,
 };
 
@@ -953,6 +970,7 @@ static BlockDriver bdrv_ftps = {
     .bdrv_detach_aio_context    = curl_detach_aio_context,
     .bdrv_attach_aio_context    = curl_attach_aio_context,
 
+    .bdrv_refresh_filename      = curl_refresh_filename,
     .sgfnt_runtime_opts         = curl_sgfnt_runtime_opts,
 };
 
-- 
2.11.0

[Qemu-devel] [PATCH v4 25/25] block/null: Generate filename even with latency-ns

[Max Reitz]

While we cannot represent the latency-ns option in a filename, it is not
a significant option so not being able to should not stop us from
generating a filename nonetheless.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/null.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/null.c b/block/null.c
index fb03fb95c0..f665bcfa05 100644
--- a/block/null.c
+++ b/block/null.c
@@ -231,7 +231,8 @@ static void null_refresh_filename(BlockDriverState *bs)
     {
         /* These options can be ignored */
         if (strcmp(qdict_entry_key(e), "filename") &&
-            strcmp(qdict_entry_key(e), "driver"))
+            strcmp(qdict_entry_key(e), "driver") &&
+            strcmp(qdict_entry_key(e), NULL_OPT_LATENCY))
         {
             return;
         }
-- 
2.11.0

Re: [Qemu-devel] [PATCH v4 07/25] block: bdrv_get_full_backing_filename's ret. val.

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 585 bytes --]

On 01/16/2017 02:48 PM, Max Reitz wrote:
> Make bdrv_get_full_backing_filename() return an allocated string instead
> of placing the result in a caller-provided buffer.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  include/block/block.h |  3 +--
>  block.c               | 26 +++++++++-----------------
>  block/qapi.c          | 12 ++----------
>  3 files changed, 12 insertions(+), 29 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v4 09/25] block: Fix bdrv_find_backing_image()

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 605 bytes --]

On 01/16/2017 02:49 PM, Max Reitz wrote:
> bdrv_find_backing_image() should use bdrv_get_full_backing_filename() or
> bdrv_make_absolute_filename() instead of trying to do what those
> functions do by itself.
> 
> path_combine_deprecated() can now be dropped, so let's do that.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block.c | 28 +++++++++++++---------------
>  1 file changed, 13 insertions(+), 15 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v4 10/25] block: Add bdrv_dirname()

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 1518 bytes --]

On 01/16/2017 02:49 PM, Max Reitz wrote:
> This function may be implemented by block drivers to derive a directory
> name from a BDS. Concatenating this g_free()-able string with a relative
> filename must result in a valid (not necessarily existing) filename, so
> this is a function that should generally be not implemented by format
> drivers, because this is protocol-specific.
> 
> If a BDS's driver does not implement this function, bdrv_dirname() will
> fall through to the BDS's file if it exists. If it does not, the
> exact_filename field will be used to generate a directory name.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  include/block/block.h     |  1 +
>  include/block/block_int.h |  1 +
>  block.c                   | 26 ++++++++++++++++++++++++++
>  3 files changed, 28 insertions(+)

> +++ b/include/block/block_int.h
> @@ -130,6 +130,7 @@ struct BlockDriver {
>      int (*bdrv_make_empty)(BlockDriverState *bs);
>  
>      void (*bdrv_refresh_filename)(BlockDriverState *bs, QDict *options);
> +    char *(*bdrv_dirname)(BlockDriverState *bs, Error **errp);

I know we've been lousy at documentation in the past, but should we
start doing a better job of documenting the contract as we add new
callbacks, rather than just the commit messages?

Based on existing practice, though, I'm okay with:
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v4 11/25] blkverify: Make bdrv_dirname() return NULL

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 592 bytes --]

On 01/16/2017 02:49 PM, Max Reitz wrote:
> blkverify's BDSs have a file BDS, but we do not want this to be
> preferred over the raw node. There is no way to decide between the two
> (and not really a reason to, either), so just return NULL in blkverify's
> implementation of bdrv_dirname().
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block/blkverify.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v4 12/25] quorum: Make bdrv_dirname() return NULL

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 575 bytes --]

On 01/16/2017 02:49 PM, Max Reitz wrote:
> While the common implementation for bdrv_dirname() should return NULL
> for quorum BDSs already (because they do not have a file node and their
> exact_filename field should be empty), there is no reason not to make
> that explicit.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block/quorum.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v4 13/25] block/nbd: Implement bdrv_dirname()

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 2812 bytes --]

On 01/16/2017 02:49 PM, Max Reitz wrote:
> The idea behind this implementation is that the export name might be
> interpreted as a path (which is the only apparent interpretation of
> relative filenames for NBD paths).
> 
> The default implementation of bdrv_dirname() would handle that just fine
> for nbd+tcp, but not for nbd+unix, because in that case, the last
> element of the path is the Unix socket path and not the export name.
> Therefore, we need to implement an own bdrv_dirname() which uses the
> legacy NBD URL which has the export name at the end.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block/nbd.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> diff --git a/block/nbd.c b/block/nbd.c
> index 35f24be069..42f0cd638c 100644
> --- a/block/nbd.c
> +++ b/block/nbd.c
> @@ -552,6 +552,34 @@ static void nbd_refresh_filename(BlockDriverState *bs, QDict *options)
>      bs->full_open_options = opts;
>  }
>  
> +static char *nbd_dirname(BlockDriverState *bs, Error **errp)
> +{
> +    BDRVNBDState *s = bs->opaque;
> +    const char *host = NULL, *port = NULL, *path = NULL;
> +
> +    if (s->saddr->type == SOCKET_ADDRESS_KIND_INET) {
> +        const InetSocketAddress *inet = s->saddr->u.inet.data;
> +        if (!inet->has_ipv4 && !inet->has_ipv6 && !inet->has_to) {
> +            host = inet->host;
> +            port = inet->port;
> +        }
> +    } else if (s->saddr->type == SOCKET_ADDRESS_KIND_UNIX) {
> +        path = s->saddr->u.q_unix.data->path;
> +    }
> +

Should we be catering to SOCKET_ADDRESS_KIND_VSOCK or
SOCKET_ADDRESS_KIND_FD (if only to assert that they aren't possible with
NBD)?

> +    if (path) {
> +        return g_strdup_printf("nbd:unix:%s:exportname=%s%s", path,
> +                               s->export ?: "", s->export ? "/" : "");
> +    } else if (host) {
> +        return g_strdup_printf("nbd://%s:%s/%s%s", host, port,
> +                               s->export ?: "", s->export ? "/" : "");
> +    }
> +
> +    error_setg(errp, "Cannot generate a base directory for NBD node '%s'",
> +               bs->filename);
> +    return NULL;
> +}
> +

The NBD protocol doesn't require the server to support directories, but
also doesn't place any requirements on export names, so this approach
assumes a particular server behavior, but is probably as good as any
other approach.  But I'm still not sold that we need this, vs. just
declaring that NBD has no directory structure and therefore we always
return NULL (even with nbd+tcp, and whether or not the older nbd: URI
was used).  So I'm not quite ready for R-b on this one yet.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v4 10/25] block: Add bdrv_dirname()

[Max Reitz]

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On 17.01.2017 00:02, Eric Blake wrote:
> On 01/16/2017 02:49 PM, Max Reitz wrote:
>> This function may be implemented by block drivers to derive a directory
>> name from a BDS. Concatenating this g_free()-able string with a relative
>> filename must result in a valid (not necessarily existing) filename, so
>> this is a function that should generally be not implemented by format
>> drivers, because this is protocol-specific.
>>
>> If a BDS's driver does not implement this function, bdrv_dirname() will
>> fall through to the BDS's file if it exists. If it does not, the
>> exact_filename field will be used to generate a directory name.
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>  include/block/block.h     |  1 +
>>  include/block/block_int.h |  1 +
>>  block.c                   | 26 ++++++++++++++++++++++++++
>>  3 files changed, 28 insertions(+)
> 
>> +++ b/include/block/block_int.h
>> @@ -130,6 +130,7 @@ struct BlockDriver {
>>      int (*bdrv_make_empty)(BlockDriverState *bs);
>>  
>>      void (*bdrv_refresh_filename)(BlockDriverState *bs, QDict *options);
>> +    char *(*bdrv_dirname)(BlockDriverState *bs, Error **errp);
> 
> I know we've been lousy at documentation in the past, but should we
> start doing a better job of documenting the contract as we add new
> callbacks, rather than just the commit messages?

Good point, I'll add a comment.

> Based on existing practice, though, I'm okay with:
> Reviewed-by: Eric Blake <eblake@redhat.com>

Thanks for reviewing!

Max


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Re: [Qemu-devel] [PATCH v4 13/25] block/nbd: Implement bdrv_dirname()

[Max Reitz]

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On 17.01.2017 00:21, Eric Blake wrote:
> On 01/16/2017 02:49 PM, Max Reitz wrote:
>> The idea behind this implementation is that the export name might be
>> interpreted as a path (which is the only apparent interpretation of
>> relative filenames for NBD paths).
>>
>> The default implementation of bdrv_dirname() would handle that just fine
>> for nbd+tcp, but not for nbd+unix, because in that case, the last
>> element of the path is the Unix socket path and not the export name.
>> Therefore, we need to implement an own bdrv_dirname() which uses the
>> legacy NBD URL which has the export name at the end.
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>  block/nbd.c | 31 +++++++++++++++++++++++++++++++
>>  1 file changed, 31 insertions(+)
>>
>> diff --git a/block/nbd.c b/block/nbd.c
>> index 35f24be069..42f0cd638c 100644
>> --- a/block/nbd.c
>> +++ b/block/nbd.c
>> @@ -552,6 +552,34 @@ static void nbd_refresh_filename(BlockDriverState *bs, QDict *options)
>>      bs->full_open_options = opts;
>>  }
>>  
>> +static char *nbd_dirname(BlockDriverState *bs, Error **errp)
>> +{
>> +    BDRVNBDState *s = bs->opaque;
>> +    const char *host = NULL, *port = NULL, *path = NULL;
>> +
>> +    if (s->saddr->type == SOCKET_ADDRESS_KIND_INET) {
>> +        const InetSocketAddress *inet = s->saddr->u.inet.data;
>> +        if (!inet->has_ipv4 && !inet->has_ipv6 && !inet->has_to) {
>> +            host = inet->host;
>> +            port = inet->port;
>> +        }
>> +    } else if (s->saddr->type == SOCKET_ADDRESS_KIND_UNIX) {
>> +        path = s->saddr->u.q_unix.data->path;
>> +    }
>> +
> 
> Should we be catering to SOCKET_ADDRESS_KIND_VSOCK or
> SOCKET_ADDRESS_KIND_FD (if only to assert that they aren't possible with
> NBD)?

In those cases, the generic "Cannot generate..." error below will be
returned. I think that should be enough.

>> +    if (path) {
>> +        return g_strdup_printf("nbd:unix:%s:exportname=%s%s", path,
>> +                               s->export ?: "", s->export ? "/" : "");
>> +    } else if (host) {
>> +        return g_strdup_printf("nbd://%s:%s/%s%s", host, port,
>> +                               s->export ?: "", s->export ? "/" : "");
>> +    }
>> +
>> +    error_setg(errp, "Cannot generate a base directory for NBD node '%s'",
>> +               bs->filename);
>> +    return NULL;
>> +}
>> +
> 
> The NBD protocol doesn't require the server to support directories, but
> also doesn't place any requirements on export names, so this approach
> assumes a particular server behavior, but is probably as good as any
> other approach.  But I'm still not sold that we need this, vs. just
> declaring that NBD has no directory structure and therefore we always
> return NULL (even with nbd+tcp, and whether or not the older nbd: URI
> was used).  So I'm not quite ready for R-b on this one yet.

Right. Perhaps it's better to just always make it an error for now and
maybe revisit it later if someone asks for it (which I can't imagine...).

Max


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