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block/io: Take reqs_lock for tracked_requests

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bdrv_co_get_self_request() does not take a lock around iterating through
bs->tracked_requests.  With multiqueue, it may thus iterate over a list
that is in the process of being modified, producing an assertion
failure:

../block/file-posix.c:3702: raw_do_pwrite_zeroes: Assertion `req' failed.

[0] abort() at /lib64/libc.so.6
[1] __assert_fail_base.cold() at /lib64/libc.so.6
[2] raw_do_pwrite_zeroes() at ../block/file-posix.c:3702
[3] bdrv_co_do_pwrite_zeroes() at ../block/io.c:1910
[4] bdrv_aligned_pwritev() at ../block/io.c:2109
[5] bdrv_co_do_zero_pwritev() at ../block/io.c:2192
[6] bdrv_co_pwritev_part() at ../block/io.c:2292
[7] bdrv_co_pwritev() at ../block/io.c:2225
[8] handle_alloc_space() at ../block/qcow2.c:2573
[9] qcow2_co_pwritev_task() at ../block/qcow2.c:2625

Fix this by taking reqs_lock.

Cc: qemu-stable@nongnu.org
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
Message-ID: <20251110154854.151484-11-hreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Hanna Czenczek 2025-11-10 16:48:45 +01:00 • committed by Kevin Wolf
parent ac3520f599
commit 9b9ee60c07
1 changed files with 3 additions and 0 deletions
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3
block/io.c
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@ -718,11 +718,14 @@ BdrvTrackedRequest *coroutine_fn bdrv_co_get_self_request(BlockDriverState *bs)
Coroutine *self = qemu_coroutine_self();
IO_CODE();
qemu_mutex_lock(&bs->reqs_lock);
QLIST_FOREACH(req, &bs->tracked_requests, list) {
if (req->co == self) {
qemu_mutex_unlock(&bs->reqs_lock);
return req;
}
}
qemu_mutex_unlock(&bs->reqs_lock);
return NULL;
}