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* [PATCH] block/copy-on-read: use bdrv_drop_filter() and drop s->active
@ 2021-05-06 19:41 Vladimir Sementsov-Ogievskiy
  2021-05-07 16:45 ` Max Reitz
  0 siblings, 1 reply; 3+ messages in thread
From: Vladimir Sementsov-Ogievskiy @ 2021-05-06 19:41 UTC (permalink / raw)
  To: qemu-block; +Cc: qemu-devel, mreitz, kwolf, vsementsov

Now, after huge update of block graph permission update algorithm, we
don't need this workaround with active state of the filter. Drop it and
use new smart bdrv_drop_filter() function.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/copy-on-read.c | 33 +--------------------------------
 1 file changed, 1 insertion(+), 32 deletions(-)

diff --git a/block/copy-on-read.c b/block/copy-on-read.c
index 9cad9e1b8c..c428682272 100644
--- a/block/copy-on-read.c
+++ b/block/copy-on-read.c
@@ -29,7 +29,6 @@
 
 
 typedef struct BDRVStateCOR {
-    bool active;
     BlockDriverState *bottom_bs;
     bool chain_frozen;
 } BDRVStateCOR;
@@ -89,7 +88,6 @@ static int cor_open(BlockDriverState *bs, QDict *options, int flags,
          */
         bdrv_ref(bottom_bs);
     }
-    state->active = true;
     state->bottom_bs = bottom_bs;
 
     /*
@@ -112,17 +110,6 @@ static void cor_child_perm(BlockDriverState *bs, BdrvChild *c,
                            uint64_t perm, uint64_t shared,
                            uint64_t *nperm, uint64_t *nshared)
 {
-    BDRVStateCOR *s = bs->opaque;
-
-    if (!s->active) {
-        /*
-         * While the filter is being removed
-         */
-        *nperm = 0;
-        *nshared = BLK_PERM_ALL;
-        return;
-    }
-
     *nperm = perm & PERM_PASSTHROUGH;
     *nshared = (shared & PERM_PASSTHROUGH) | PERM_UNCHANGED;
 
@@ -280,32 +267,14 @@ static BlockDriver bdrv_copy_on_read = {
 
 void bdrv_cor_filter_drop(BlockDriverState *cor_filter_bs)
 {
-    BdrvChild *child;
-    BlockDriverState *bs;
     BDRVStateCOR *s = cor_filter_bs->opaque;
 
-    child = bdrv_filter_child(cor_filter_bs);
-    if (!child) {
-        return;
-    }
-    bs = child->bs;
-
-    /* Retain the BDS until we complete the graph change. */
-    bdrv_ref(bs);
-    /* Hold a guest back from writing while permissions are being reset. */
-    bdrv_drained_begin(bs);
-    /* Drop permissions before the graph change. */
-    s->active = false;
     /* unfreeze, as otherwise bdrv_replace_node() will fail */
     if (s->chain_frozen) {
         s->chain_frozen = false;
         bdrv_unfreeze_backing_chain(cor_filter_bs, s->bottom_bs);
     }
-    bdrv_child_refresh_perms(cor_filter_bs, child, &error_abort);
-    bdrv_replace_node(cor_filter_bs, bs, &error_abort);
-
-    bdrv_drained_end(bs);
-    bdrv_unref(bs);
+    bdrv_drop_filter(cor_filter_bs, &error_abort);
     bdrv_unref(cor_filter_bs);
 }
 
-- 
2.29.2



^ permalink raw reply related	[flat|nested] 3+ messages in thread
* [PATCH 00/21] block: publish backup-top filter
@ 2021-05-17  6:44 Vladimir Sementsov-Ogievskiy
  2021-05-17  6:44 ` [PATCH] block/copy-on-read: use bdrv_drop_filter() and drop s->active Vladimir Sementsov-Ogievskiy
  0 siblings, 1 reply; 3+ messages in thread
From: Vladimir Sementsov-Ogievskiy @ 2021-05-17  6:44 UTC (permalink / raw)
  To: qemu-block
  Cc: qemu-devel, armbru, eblake, ehabkost, berrange, pbonzini,
	vsementsov, jsnow, mreitz, kwolf, den

Hi all!

We have image fleecing scheme to export point-in-time state of active
disk (iotest 222):


                                      backup(sync=none)
                     ┌───────────────────────────────────────┐
                     ▼                                       │
┌────────────┐     ┌────────────────┐  backing             ┌─────────────┐
│ NBD export │ ─── │ temp qcow2 img │ ───────────────────▶ │ active disk │
└────────────┘     └────────────────┘                      └─────────────┘
                                                             ▲
┌────────────┐                                               │
│ guest blk  │ ──────────────────────────────────────────────┘
└────────────┘                        


Actually, backup job inserts a backup-top filter, so in detail it looks
like:

                                      backup(sync=none)
                     ┌───────────────────────────────────────┐
                     ▼                                       │
┌────────────┐     ┌────────────────┐  backing             ┌─────────────┐
│ NBD export │ ─── │ temp qcow2 img │ ───────────────────▶ │ active disk │
└────────────┘     └────────────────┘                      └─────────────┘
                     ▲                                       ▲
                     │ target                                │
                     │                                       │
┌────────────┐     ┌────────────────┐  backing               │
│ guest blk  │ ──▶ │   backup-top   │ ───────────────────────┘
└────────────┘     └────────────────┘

And job does nothing here. In a new blockdev world user is intended to
operate on node level, and insert/remove filters by hand. Let's get rid
of job in the scheme:

┌────────────┐     ┌────────────────┐  backing             ┌─────────────┐
│ NBD export │ ─── │ temp qcow2 img │ ───────────────────▶ │ active disk │
└────────────┘     └────────────────┘                      └─────────────┘
                     ▲                                       ▲
                     │ target                                │
                     │                                       │
┌────────────┐     ┌────────────────┐  backing               │
│ guest blk  │ ──▶ │   backup-top   │ ───────────────────────┘
└────────────┘     └────────────────┘


The series prepares qom-set to make possible inserting filters above
root node (patches 01-04), rename backup-top to copy-before-write, do
other preparations for publishing the filter, and finally publish it,
add qapi interface and test new fleecing scheme in 222.

Vladimir Sementsov-Ogievskiy (21):
  block: introduce bdrv_replace_child_bs()
  block: introduce blk_replace_bs
  qdev-properties: PropertyInfo: add realized_set_allowed field
  qdev: allow setting drive property for realized device
  block: rename backup-top to copy-before-write
  block/backup: drop support for copy_range
  block-copy: always set BDRV_REQ_SERIALISING flag
  block/backup: stricter backup_calculate_cluster_size()
  block/backup: move cluster size calculation to block-copy
  block/copy-before-write: relax permission requirements when no parents
  block/copy-before-write: use file child instead of backing
  block/copy-before-write: bdrv_cbw_append(): replace child at last
  block/copy-before-write: introduce cbw_init()
  block/copy-before-write: cbw_init(): rename variables
  block/copy-before-write: cbw_init(): use file child after attaching
  block/copy-before-write: cbw_init(): use options
  block/block-copy: switch to fully set bitmap by default
  block/block-copy: make setting progress optional
  block/copy-before-write: make public block driver
  qapi: publish copy-before-write filter
  itotests/222: add test-case for copy-before-write filter

 qapi/block-core.json                        |  22 +-
 block/{backup-top.h => copy-before-write.h} |  26 +-
 include/block/block-copy.h                  |   4 +-
 include/block/block.h                       |   2 +
 include/hw/qdev-properties.h                |   1 +
 include/sysemu/block-backend.h              |   1 +
 block.c                                     |  36 +++
 block/backup-top.c                          | 253 -------------------
 block/backup.c                              | 115 ++-------
 block/block-backend.c                       |   8 +
 block/block-copy.c                          |  95 +++++++-
 block/copy-before-write.c                   | 257 ++++++++++++++++++++
 hw/core/qdev-properties-system.c            |  30 ++-
 hw/core/qdev-properties.c                   |   6 +-
 MAINTAINERS                                 |   4 +-
 block/meson.build                           |   2 +-
 tests/qemu-iotests/222                      |  56 ++++-
 tests/qemu-iotests/222.out                  |  72 ++++++
 tests/qemu-iotests/283                      |  35 ++-
 tests/qemu-iotests/283.out                  |   4 +-
 20 files changed, 606 insertions(+), 423 deletions(-)
 rename block/{backup-top.h => copy-before-write.h} (56%)
 delete mode 100644 block/backup-top.c
 create mode 100644 block/copy-before-write.c

-- 
2.29.2



^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-05-17  6:47 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-05-06 19:41 [PATCH] block/copy-on-read: use bdrv_drop_filter() and drop s->active Vladimir Sementsov-Ogievskiy
2021-05-07 16:45 ` Max Reitz
2021-05-17  6:44 [PATCH 00/21] block: publish backup-top filter Vladimir Sementsov-Ogievskiy
2021-05-17  6:44 ` [PATCH] block/copy-on-read: use bdrv_drop_filter() and drop s->active Vladimir Sementsov-Ogievskiy

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