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Kevin Wolf
8eeaa706ba
When new requests arrive at a BlockBackend that is currently drained, these requests are queued until the drain section ends. There is a race window between blk_root_drained_end() waking up a queued request in an iothread from the main thread and blk_wait_while_drained() actually being woken up in the iothread and calling blk_inc_in_flight(). If the BlockBackend is drained again during this window, drain won't wait for this request and it will sneak in when the BlockBackend is already supposed to be quiesced. This causes assertion failures in bdrv_drain_all_begin() and can have other unintended consequences. Fix this by increasing the in_flight counter immediately when scheduling the request to be resumed so that the next drain will wait for it to complete. Cc: qemu-stable@nongnu.org Reported-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-ID: <20251119172720.135424-1-kwolf@redhat.com> Reviewed-by: Hanna Czenczek <hreitz@redhat.com> Tested-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> Reviewed-by: Fiona Ebner <f.ebner@proxmox.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>