This function, in addition to be called by a generated_co_wrapper, is also called by the blk_* API. The strategy is to always take the lock at the function called when the coroutine is created, to avoid recursive locking.
Protecting bdrv_co_truncate() implies that BlockDriver->bdrv_co_truncate() is always called with graph rdlock taken. Signed-off-by: Emanuele Giuseppe Esposito <eespo...@redhat.com> --- block/block-backend.c | 1 + block/io.c | 1 + include/block/block_int-common.h | 2 ++ 3 files changed, 4 insertions(+) diff --git a/block/block-backend.c b/block/block-backend.c index 333d50fb3f..0686cd6942 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -2370,6 +2370,7 @@ int coroutine_fn blk_co_truncate(BlockBackend *blk, int64_t offset, bool exact, Error **errp) { IO_OR_GS_CODE(); + GRAPH_RDLOCK_GUARD(); if (!blk_is_available(blk)) { error_setg(errp, "No medium inserted"); return -ENOMEDIUM; diff --git a/block/io.c b/block/io.c index 9bcb19e5ee..ac12725fb2 100644 --- a/block/io.c +++ b/block/io.c @@ -3295,6 +3295,7 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact, int64_t old_size, new_bytes; int ret; IO_CODE(); + assert_bdrv_graph_readable(); /* if bs->drv == NULL, bs is closed, so there's nothing to do here */ if (!drv) { diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index fd9f40a815..d666b0c441 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -681,6 +681,8 @@ struct BlockDriver { * * If @exact is true and this function fails but would succeed * with @exact = false, it should return -ENOTSUP. + * + * Called with graph rdlock held. */ int coroutine_fn (*bdrv_co_truncate)(BlockDriverState *bs, int64_t offset, bool exact, PreallocMode prealloc, -- 2.31.1