This function, in addition to be called by a generated_co_wrapper, is also called elsewhere else. The strategy is to always take the lock at the function called when the coroutine is created, to avoid recursive locking.
By protecting brdv_co_pwrite, we also automatically protect the following other generated_co_wrappers: blk_co_pwrite blk_co_pwritev blk_co_pwritev_part blk_co_pwrite_compressed blk_co_pwrite_zeroes Protecting bdrv_driver_pwritev_compressed() and bdrv_driver_pwritev_compressed() implies that the following BlockDriver callbacks always called with graph rdlock taken: - bdrv_aio_pwritev - bdrv_co_writev - bdrv_co_pwritev - bdrv_co_pwritev_part - bdrv_co_pwritev_compressed - bdrv_co_pwritev_compressed_part Signed-off-by: Emanuele Giuseppe Esposito <eespo...@redhat.com> --- block/block-backend.c | 1 + block/block-copy.c | 8 ++++++-- block/io.c | 2 ++ include/block/block_int-common.h | 6 ++++++ include/block/block_int-io.h | 1 + 5 files changed, 16 insertions(+), 2 deletions(-) diff --git a/block/block-backend.c b/block/block-backend.c index 0686cd6942..d48ec3a2ac 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -1363,6 +1363,7 @@ blk_co_do_pwritev_part(BlockBackend *blk, int64_t offset, int64_t bytes, IO_CODE(); blk_wait_while_drained(blk); + GRAPH_RDLOCK_GUARD(); /* Call blk_bs() only after waiting, the graph may have changed */ bs = blk_bs(blk); diff --git a/block/block-copy.c b/block/block-copy.c index f33ab1d0b6..dabf461112 100644 --- a/block/block-copy.c +++ b/block/block-copy.c @@ -464,6 +464,8 @@ static coroutine_fn int block_copy_task_run(AioTaskPool *pool, * a full-size buffer or disabled if the copy_range attempt fails. The output * value of @method should be used for subsequent tasks. * Returns 0 on success. + * + * Called with graph rdlock taken. */ static int coroutine_fn block_copy_do_copy(BlockCopyState *s, int64_t offset, int64_t bytes, @@ -554,8 +556,10 @@ static coroutine_fn int block_copy_task_entry(AioTask *task) BlockCopyMethod method = t->method; int ret; - ret = block_copy_do_copy(s, t->req.offset, t->req.bytes, &method, - &error_is_read); + WITH_GRAPH_RDLOCK_GUARD() { + ret = block_copy_do_copy(s, t->req.offset, t->req.bytes, &method, + &error_is_read); + } WITH_QEMU_LOCK_GUARD(&s->lock) { if (s->method == t->method) { diff --git a/block/io.c b/block/io.c index ac12725fb2..9280fb9f38 100644 --- a/block/io.c +++ b/block/io.c @@ -1012,6 +1012,7 @@ static int coroutine_fn bdrv_driver_pwritev(BlockDriverState *bs, unsigned int nb_sectors; QEMUIOVector local_qiov; int ret; + assert_bdrv_graph_readable(); bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort); @@ -1090,6 +1091,7 @@ bdrv_driver_pwritev_compressed(BlockDriverState *bs, int64_t offset, BlockDriver *drv = bs->drv; QEMUIOVector local_qiov; int ret; + assert_bdrv_graph_readable(); bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort); diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index f285a6b8f7..d44f825d95 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -479,6 +479,7 @@ struct BlockDriver { BlockAIOCB *(*bdrv_aio_preadv)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque); + /* Called with graph rdlock taken. */ BlockAIOCB *(*bdrv_aio_pwritev)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque); @@ -515,6 +516,7 @@ struct BlockDriver { QEMUIOVector *qiov, size_t qiov_offset, BdrvRequestFlags flags); + /* Called with graph rdlock taken. */ int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int flags); @@ -532,10 +534,12 @@ struct BlockDriver { * no larger than 'max_transfer'. * * The buffer in @qiov may point directly to guest memory. + * Called with graph rdlock taken. */ int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags); + /* Called with graph rdlock taken. */ int coroutine_fn (*bdrv_co_pwritev_part)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset, BdrvRequestFlags flags); @@ -693,8 +697,10 @@ struct BlockDriver { BlockMeasureInfo *(*bdrv_measure)(QemuOpts *opts, BlockDriverState *in_bs, Error **errp); + /* Called with graph rdlock held. */ int coroutine_fn (*bdrv_co_pwritev_compressed)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov); + /* Called with graph rdlock held. */ int coroutine_fn (*bdrv_co_pwritev_compressed_part)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset); diff --git a/include/block/block_int-io.h b/include/block/block_int-io.h index 8bc061ebb8..ae88507d6a 100644 --- a/include/block/block_int-io.h +++ b/include/block/block_int-io.h @@ -69,6 +69,7 @@ static inline int coroutine_fn bdrv_co_pwrite(BdrvChild *child, { QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes); IO_CODE(); + assert_bdrv_graph_readable(); return bdrv_co_pwritev(child, offset, bytes, &qiov, flags); } -- 2.31.1