From c86422c5549c0983b4b4525b8f56a1c69dd67aa1 Mon Sep 17 00:00:00 2001 From: Emanuele Giuseppe Esposito Date: Fri, 13 Jan 2023 21:42:04 +0100 Subject: block: Convert bdrv_refresh_total_sectors() to co_wrapper_mixed BlockDriver->bdrv_getlength is categorized as IO callback, and it currently doesn't run in a coroutine. We should let it take a graph rdlock since the callback traverses the block nodes graph, which however is only possible in a coroutine. Therefore turn it into a co_wrapper to move the actual function into a coroutine where the lock can be taken. Because now this function creates a new coroutine and polls, we need to take the AioContext lock where it is missing, for the only reason that internally co_wrapper calls AIO_WAIT_WHILE and it expects to release the AioContext lock. This is especially messy when a co_wrapper creates a coroutine and polls in bdrv_open_driver, because this function has so many callers in so many context that it can easily lead to deadlocks. Therefore the new rule for bdrv_open_driver is that the caller must always hold the AioContext lock of the given bs (except if it is a coroutine), because the function calls bdrv_refresh_total_sectors() which is now a co_wrapper. Once the rwlock is ultimated and placed in every place it needs to be, we will poll using AIO_WAIT_WHILE_UNLOCKED and remove the AioContext lock. Signed-off-by: Emanuele Giuseppe Esposito Signed-off-by: Kevin Wolf Message-Id: <20230113204212.359076-7-kwolf@redhat.com> Reviewed-by: Emanuele Giuseppe Esposito Signed-off-by: Kevin Wolf --- include/block/block-io.h | 8 ++++++-- include/block/block_int-common.h | 2 +- include/block/block_int-io.h | 5 ++++- include/sysemu/block-backend-io.h | 10 ++++++++-- 4 files changed, 19 insertions(+), 6 deletions(-) (limited to 'include') diff --git a/include/block/block-io.h b/include/block/block-io.h index f27d935982..dcb6270f77 100644 --- a/include/block/block-io.h +++ b/include/block/block-io.h @@ -76,8 +76,12 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact, PreallocMode prealloc, BdrvRequestFlags flags, Error **errp); -int64_t bdrv_nb_sectors(BlockDriverState *bs); -int64_t bdrv_getlength(BlockDriverState *bs); +int64_t coroutine_fn bdrv_co_nb_sectors(BlockDriverState *bs); +int64_t co_wrapper_mixed bdrv_nb_sectors(BlockDriverState *bs); + +int64_t coroutine_fn bdrv_co_getlength(BlockDriverState *bs); +int64_t co_wrapper_mixed bdrv_getlength(BlockDriverState *bs); + int64_t bdrv_get_allocated_file_size(BlockDriverState *bs); BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts, BlockDriverState *in_bs, Error **errp); diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index 9ec68f515c..5381681fbc 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -680,7 +680,7 @@ struct BlockDriver { int coroutine_fn (*bdrv_co_truncate)(BlockDriverState *bs, int64_t offset, bool exact, PreallocMode prealloc, BdrvRequestFlags flags, Error **errp); - int64_t (*bdrv_getlength)(BlockDriverState *bs); + int64_t coroutine_fn (*bdrv_co_getlength)(BlockDriverState *bs); int64_t (*bdrv_get_allocated_file_size)(BlockDriverState *bs); BlockMeasureInfo *(*bdrv_measure)(QemuOpts *opts, BlockDriverState *in_bs, Error **errp); diff --git a/include/block/block_int-io.h b/include/block/block_int-io.h index 37b0fd974b..4430bf4c4a 100644 --- a/include/block/block_int-io.h +++ b/include/block/block_int-io.h @@ -122,7 +122,10 @@ int coroutine_fn bdrv_co_copy_range_to(BdrvChild *src, int64_t src_offset, BdrvRequestFlags read_flags, BdrvRequestFlags write_flags); -int bdrv_refresh_total_sectors(BlockDriverState *bs, int64_t hint); +int coroutine_fn bdrv_co_refresh_total_sectors(BlockDriverState *bs, + int64_t hint); +int co_wrapper_mixed +bdrv_refresh_total_sectors(BlockDriverState *bs, int64_t hint); BdrvChild *bdrv_cow_child(BlockDriverState *bs); BdrvChild *bdrv_filter_child(BlockDriverState *bs); diff --git a/include/sysemu/block-backend-io.h b/include/sysemu/block-backend-io.h index 7cc96a56c7..ce013b3312 100644 --- a/include/sysemu/block-backend-io.h +++ b/include/sysemu/block-backend-io.h @@ -61,9 +61,15 @@ bool co_wrapper_mixed blk_is_inserted(BlockBackend *blk); bool blk_is_available(BlockBackend *blk); void blk_lock_medium(BlockBackend *blk, bool locked); void blk_eject(BlockBackend *blk, bool eject_flag); -int64_t blk_getlength(BlockBackend *blk); + +int64_t coroutine_fn blk_co_getlength(BlockBackend *blk); +int64_t co_wrapper_mixed blk_getlength(BlockBackend *blk); + void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr); -int64_t blk_nb_sectors(BlockBackend *blk); + +int64_t coroutine_fn blk_co_nb_sectors(BlockBackend *blk); +int64_t co_wrapper_mixed blk_nb_sectors(BlockBackend *blk); + void *blk_try_blockalign(BlockBackend *blk, size_t size); void *blk_blockalign(BlockBackend *blk, size_t size); bool blk_is_writable(BlockBackend *blk); -- cgit 1.4.1