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[PATCH] backup: don't acquire aio_context in backup_clean
From: |
Stefan Reiter |
Subject: |
[PATCH] backup: don't acquire aio_context in backup_clean |
Date: |
Wed, 25 Mar 2020 16:50:55 +0100 |
backup_clean is only ever called as a handler via job_exit, which
already acquires the job's context. The job's context is guaranteed to
be the same as the one used by backup_top via backup_job_create.
Since the previous logic effectively acquired the lock twice, this
broke cleanup of backups for disks using IO threads, since the BDRV_POLL_WHILE
in bdrv_backup_top_drop -> bdrv_do_drained_begin would only release the lock
once, thus deadlocking with the IO thread.
Signed-off-by: Stefan Reiter <address@hidden>
---
This is a fix for the issue discussed in this part of the thread:
https://lists.gnu.org/archive/html/qemu-devel/2020-03/msg07639.html
...not the original problem (core dump) posted by Dietmar.
I've still seen it occasionally hang during a backup abort. I'm trying to figure
out why that happens, stack trace indicates a similar problem with the main
thread hanging at bdrv_do_drained_begin, though I have no clue why as of yet.
block/backup.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/block/backup.c b/block/backup.c
index 7430ca5883..a7a7dcaf4c 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -126,11 +126,7 @@ static void backup_abort(Job *job)
static void backup_clean(Job *job)
{
BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
- AioContext *aio_context = bdrv_get_aio_context(s->backup_top);
-
- aio_context_acquire(aio_context);
bdrv_backup_top_drop(s->backup_top);
- aio_context_release(aio_context);
}
void backup_do_checkpoint(BlockJob *job, Error **errp)
--
2.25.2
- backup transaction with io-thread core dumps, Dietmar Maurer, 2020/03/24
- Re: backup transaction with io-thread core dumps, Dietmar Maurer, 2020/03/24
- Re: backup transaction with io-thread core dumps, Dietmar Maurer, 2020/03/24
- Re: backup transaction with io-thread core dumps, Max Reitz, 2020/03/24
- Re: backup transaction with io-thread core dumps, Dietmar Maurer, 2020/03/24
- Re: backup transaction with io-thread core dumps, Dietmar Maurer, 2020/03/24
- Re: backup transaction with io-thread core dumps, Stefan Reiter, 2020/03/25
- Re: backup transaction with io-thread core dumps, Vladimir Sementsov-Ogievskiy, 2020/03/25
- [PATCH] backup: don't acquire aio_context in backup_clean,
Stefan Reiter <=
- Re: [PATCH] backup: don't acquire aio_context in backup_clean, Vladimir Sementsov-Ogievskiy, 2020/03/26
- Re: [PATCH] backup: don't acquire aio_context in backup_clean, Stefan Reiter, 2020/03/26
- Re: [PATCH] backup: don't acquire aio_context in backup_clean, Vladimir Sementsov-Ogievskiy, 2020/03/26
- Re: [PATCH] backup: don't acquire aio_context in backup_clean, Sergio Lopez, 2020/03/26
- Re: backup transaction with io-thread core dumps, Sergio Lopez, 2020/03/25
- Re: backup transaction with io-thread core dumps, Sergio Lopez, 2020/03/25
- Re: backup transaction with io-thread core dumps, Dietmar Maurer, 2020/03/25
- Re: backup transaction with io-thread core dumps, Sergio Lopez, 2020/03/25
- Re: backup transaction with io-thread core dumps, Dietmar Maurer, 2020/03/25
- Re: backup transaction with io-thread core dumps, Sergio Lopez, 2020/03/26