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ac2ae233a0
qemu/block
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Kevin Wolf ac2ae233a0 block: Introduce bdrv_schedule_unref() 
bdrv_unref() is called by a lot of places that need to hold the graph
lock (it naturally happens in the context of operations that change the
graph). However, bdrv_unref() takes the graph writer lock internally, so
it can't actually be called while already holding a graph lock without
causing a deadlock.

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

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

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

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

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

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230911094620.45040-6-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-09-20 17:46:01 +02:00
..
export block: spelling fixes 2023-09-08 13:08:52 +03:00
monitor meson: Replace softmmu_ss -> system_ss 2023-06-20 10:01:30 +02:00
accounting.c block: add missed block_acct_setup with new block device init procedure 2022-09-30 18:42:34 +02:00
aio_task.c block/aio_task: assert max_busy_tasks is greater than 0 2021-10-05 18:56:41 +02:00
amend.c block: Mark BlockDriver callbacks for amend job GRAPH_RDLOCK 2023-05-10 14:16:54 +02:00
backup.c Block layer patches 2023-02-24 15:09:39 +00:00
blkdebug.c blkdebug: add missing coroutine_fn annotation 2023-04-25 13:17:28 +02:00
blkio.c block/blkio: add more comments on the fd passing handling 2023-08-03 11:28:43 -04:00
blklogwrites.c block: Mark bdrv_co_refresh_total_sectors() and callers GRAPH_RDLOCK 2023-02-23 19:49:33 +01:00
blkreplay.c block: Mark bdrv_co_refresh_total_sectors() and callers GRAPH_RDLOCK 2023-02-23 19:49:33 +01:00
blkverify.c block: Mark bdrv_recurse_can_replace() and callers GRAPH_RDLOCK 2023-05-10 14:16:54 +02:00
block-backend.c block: add blk_io_plug_call() API 2023-06-01 07:34:03 -04:00
block-copy.c block: spelling fixes 2023-09-08 13:08:52 +03:00
block-gen.h block-coroutine-wrapper.py: support also basic return types 2022-12-15 16:07:43 +01:00
block-ram-registrar.c block: add BlockRAMRegistrar 2022-10-26 14:56:42 -04:00
bochs.c bochs: mark more functions as coroutine_fns and GRAPH_RDLOCK 2023-06-28 09:46:24 +02:00
cloop.c cloop: mark more functions as coroutine_fns and GRAPH_RDLOCK 2023-06-28 09:46:27 +02:00
commit.c blockjob: Adhere to rate limit even when reentered early 2023-05-19 19:12:12 +02:00
copy-before-write.c block: Make more BlockDriver definitions static 2023-09-08 17:03:09 +02:00
copy-before-write.h block/copy-before-write.h: global state API + assertions 2022-03-04 18:18:25 +01:00
copy-on-read.c block: remove has_variable_length from filters 2023-04-11 16:38:56 +02:00
copy-on-read.h Clean up ill-advised or unusual header guards 2022-05-11 16:50:01 +02:00
coroutines.h nbd: Mark nbd_co_do_establish_connection() and callers GRAPH_RDLOCK 2023-05-10 14:16:53 +02:00
create.c block: Call .bdrv_co_create(_opts) unlocked 2023-05-19 19:12:12 +02:00
crypto.c block: Call .bdrv_co_create(_opts) unlocked 2023-05-19 19:12:12 +02:00
crypto.h nomaintainer: Fix Lesser GPL version number 2020-11-15 17:04:40 +01:00
curl.c aio: remove aio_disable_external() API 2023-05-30 17:37:26 +02:00
dirty-bitmap.c block: Mark bdrv_*_dirty_bitmap() and callers GRAPH_RDLOCK 2023-02-23 19:49:32 +01:00
dmg-bz2.c Include qemu-common.h exactly where needed 2019-06-12 13:20:20 +02:00
dmg-lzfse.c block/dmg: Ignore C99 prototype declaration mismatch from <lzfse.h> 2023-03-30 15:03:36 +02:00
dmg.c dmg: mark more functions as coroutine_fns and GRAPH_RDLOCK 2023-06-28 09:46:28 +02:00
dmg.h block/dmg: Declare a type definition for DMG uncompress function 2023-04-24 13:53:44 -04:00
file-posix.c block: spelling fixes 2023-09-08 13:08:52 +03:00
file-win32.c thread-pool: avoid passing the pool parameter every time 2023-04-25 13:17:28 +02:00
filter-compress.c block: remove has_variable_length from filters 2023-04-11 16:38:56 +02:00
gluster.c cutils: Adjust signature of parse_uint[_full] 2023-06-02 12:27:19 -05:00
graph-lock.c block: Introduce bdrv_schedule_unref() 2023-09-20 17:46:01 +02:00
io_uring.c block/io_uring: convert to blk_io_plug_call() API 2023-06-01 07:34:03 -04:00
io.c Block layer patches 2023-09-11 09:11:22 -04:00
iscsi-opts.c modules: add block module annotations 2021-07-09 18:20:27 +02:00
iscsi.c block/iscsi: Document why we use raw malloc() 2023-09-08 17:03:09 +02:00
linux-aio.c block: spelling fixes 2023-09-08 13:08:52 +03:00
meson.build block/meson.build: Restore alphabetical order of files 2023-09-08 17:03:09 +02:00
mirror.c block: spelling fixes 2023-09-08 13:08:52 +03:00
nbd.c io: follow coroutine AioContext in qio_channel_yield() 2023-09-07 20:32:11 -05:00
nfs.c cutils: Adjust signature of parse_uint[_full] 2023-06-02 12:27:19 -05:00
null.c block: Convert bdrv_get_allocated_file_size() to co_wrapper 2023-02-01 16:52:32 +01:00
nvme.c block/nvme: invoke blk_io_plug_call() outside q->lock 2023-07-17 09:17:41 -04:00
parallels-ext.c include/block: Untangle inclusion loops 2023-01-20 07:24:28 +01:00
parallels.c parallels: Add data_off repairing to parallels_open() 2023-09-06 17:36:49 +02:00
parallels.h parallels: Add data_start field to BDRVParallelsState 2023-09-06 17:36:49 +02:00
plug.c block: add blk_io_plug_call() API 2023-06-01 07:34:03 -04:00
preallocate.c preallocate: Don't poll during permission updates 2023-09-20 17:46:00 +02:00
progress_meter.c coroutine: Clean up superfluous inclusion of qemu/lockable.h 2023-01-19 10:18:28 +01:00
qapi-sysemu.c block: Take main AioContext lock when calling bdrv_open() 2023-05-30 17:21:23 +02:00
qapi.c block: Remove unnecessary variable in bdrv_block_device_info 2023-09-08 17:03:09 +02:00
qcow2-bitmap.c qcow2: mark more functions as coroutine_fns and GRAPH_RDLOCK 2023-06-28 09:46:32 +02:00
qcow2-cache.c include/block: Untangle inclusion loops 2023-01-20 07:24:28 +01:00
qcow2-cluster.c block: use bdrv_co_debug_event in coroutine context 2023-06-28 09:46:34 +02:00
qcow2-refcount.c block: spelling fixes 2023-09-08 13:08:52 +03:00
qcow2-snapshot.c qcow2: mark various functions as coroutine_fn and GRAPH_RDLOCK 2023-04-25 13:17:28 +02:00
qcow2-threads.c thread-pool: avoid passing the pool parameter every time 2023-04-25 13:17:28 +02:00
qcow2.c block: add subcluster_size field to BlockDriverInfo 2023-08-30 07:39:10 -04:00
qcow2.h qcow2: mark more functions as coroutine_fns and GRAPH_RDLOCK 2023-06-28 09:46:32 +02:00
qcow.c block: use bdrv_co_debug_event in coroutine context 2023-06-28 09:46:34 +02:00
qed-check.c qed: mark more functions as coroutine_fns and GRAPH_RDLOCK 2023-06-28 09:46:20 +02:00
qed-cluster.c qed: protect table cache with CoMutex 2017-07-17 11:34:11 +08:00
qed-l2-cache.c osdep: Move memalign-related functions to their own header 2022-03-07 13:16:49 +00:00
qed-table.c block: use bdrv_co_debug_event in coroutine context 2023-06-28 09:46:34 +02:00
qed.c block: use bdrv_co_debug_event in coroutine context 2023-06-28 09:46:34 +02:00
qed.h block: Mark public read/write functions GRAPH_RDLOCK 2023-02-23 19:49:17 +01:00
quorum.c block: Mark bdrv_recurse_can_replace() and callers GRAPH_RDLOCK 2023-05-10 14:16:54 +02:00
raw-format.c block: use bdrv_co_debug_event in coroutine context 2023-06-28 09:46:34 +02:00
rbd.c block/rbd: Add support for layered encryption 2023-02-23 19:49:35 +01:00
replication.c block: remove has_variable_length from filters 2023-04-11 16:38:56 +02:00
reqlist.c block/reqlist: add reqlist_wait_all() 2022-03-07 09:33:30 +01:00
snapshot-access.c block: Make more BlockDriver definitions static 2023-09-08 17:03:09 +02:00
snapshot.c block/snapshot: drop indirection around bdrv_snapshot_fallback_ptr 2022-10-27 20:14:11 +02:00
ssh.c aio: remove aio_disable_external() API 2023-05-30 17:37:26 +02:00
stream.c blockjob: Adhere to rate limit even when reentered early 2023-05-19 19:12:12 +02:00
throttle-groups.c block/throttle-groups: throttle_group_co_io_limits_intercept(): 64bit bytes 2021-02-03 08:14:00 -06:00
throttle.c block: Mark bdrv_co_refresh_total_sectors() and callers GRAPH_RDLOCK 2023-02-23 19:49:33 +01:00
trace-events block/io_uring: convert to blk_io_plug_call() API 2023-06-01 07:34:03 -04:00
trace.h trace: switch position of headers to what Meson requires 2020-08-21 06:18:24 -04:00
vdi.c block: Call .bdrv_co_create(_opts) unlocked 2023-05-19 19:12:12 +02:00
vhdx-endian.c Include qemu-common.h exactly where needed 2019-06-12 13:20:20 +02:00
vhdx-log.c vhdx: mark more functions as coroutine_fns and GRAPH_RDLOCK 2023-06-28 09:46:30 +02:00
vhdx.c block: spelling fixes 2023-09-08 13:08:52 +03:00
vhdx.h block: spelling fixes 2023-09-08 13:08:52 +03:00
vmdk.c vmdk: Clean up bdrv_open_child() return value check 2023-09-08 17:03:09 +02:00
vpc.c block/vpc: Avoid dynamic stack allocation 2023-09-08 17:03:09 +02:00
vvfat.c vvfat: mark various functions as coroutine_fn 2023-04-25 13:17:28 +02:00
win32-aio.c aio: remove aio_disable_external() API 2023-05-30 17:37:26 +02:00
write-threshold.c include/block: Untangle inclusion loops 2023-01-20 07:24:28 +01:00