aio_context should be locked in the similar way as was done in QMP snapshot creation in the other case there are a lot of possible troubles if native AIO mode is enabled for disk.
- the command can hang (HMP thread) with missed wakeup (the operation is actually complete) io_submit ioq_submit laio_submit raw_aio_submit raw_aio_readv bdrv_co_io_em bdrv_co_readv_em bdrv_aligned_preadv bdrv_co_do_preadv bdrv_co_do_readv bdrv_co_readv qcow2_co_readv bdrv_aligned_preadv bdrv_co_do_pwritev bdrv_rw_co_entry - QEMU can assert in coroutine re-enter __GI_abort qemu_coroutine_enter bdrv_co_io_em_complete qemu_laio_process_completion qemu_laio_completion_bh aio_bh_poll aio_dispatch aio_poll iothread_run qemu_fopen_bdrv and bdrv_fclose are used in real snapshot operations only along with block drivers. This change should influence only HMP snapshot operations. AioContext lock is reqursive. Thus nested locking should not be a problem. Signed-off-by: Denis V. Lunev <d...@openvz.org> CC: Stefan Hajnoczi <stefa...@redhat.com> CC: Paolo Bonzini <pbonz...@redhat.com> CC: Juan Quintela <quint...@redhat.com> CC: Amit Shah <amit.s...@redhat.com> --- block/snapshot.c | 5 +++++ migration/savevm.c | 18 +++++++++++++++--- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/block/snapshot.c b/block/snapshot.c index 89500f2..f6fa17a 100644 --- a/block/snapshot.c +++ b/block/snapshot.c @@ -259,6 +259,9 @@ void bdrv_snapshot_delete_by_id_or_name(BlockDriverState *bs, { int ret; Error *local_err = NULL; + AioContext *aio_context = bdrv_get_aio_context(bs); + + aio_context_acquire(aio_context); ret = bdrv_snapshot_delete(bs, id_or_name, NULL, &local_err); if (ret == -ENOENT || ret == -EINVAL) { @@ -267,6 +270,8 @@ void bdrv_snapshot_delete_by_id_or_name(BlockDriverState *bs, ret = bdrv_snapshot_delete(bs, NULL, id_or_name, &local_err); } + aio_context_release(aio_context); + if (ret < 0) { error_propagate(errp, local_err); } diff --git a/migration/savevm.c b/migration/savevm.c index dbcc39a..1653f56 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -153,7 +153,11 @@ static ssize_t block_get_buffer(void *opaque, uint8_t *buf, int64_t pos, static int bdrv_fclose(void *opaque) { - return bdrv_flush(opaque); + BlockDriverState *bs = (BlockDriverState *)opaque; + int ret = bdrv_flush(bs); + + aio_context_release(bdrv_get_aio_context(bs)); + return ret; } static const QEMUFileOps bdrv_read_ops = { @@ -169,10 +173,18 @@ static const QEMUFileOps bdrv_write_ops = { static QEMUFile *qemu_fopen_bdrv(BlockDriverState *bs, int is_writable) { + QEMUFile *file; + if (is_writable) { - return qemu_fopen_ops(bs, &bdrv_write_ops); + file = qemu_fopen_ops(bs, &bdrv_write_ops); + } else { + file = qemu_fopen_ops(bs, &bdrv_read_ops); + } + + if (file != NULL) { + aio_context_acquire(bdrv_get_aio_context(bs)); } - return qemu_fopen_ops(bs, &bdrv_read_ops); + return file; } -- 2.1.4