From 6b89e851fabf78d7fb090bcdc71789ea1ef55c9b Mon Sep 17 00:00:00 2001 From: Fiona Ebner Date: Fri, 30 May 2025 17:11:01 +0200 Subject: block: add bdrv_graph_wrlock_drained() convenience wrapper Many write-locked sections are also drained sections. A new bdrv_graph_wrunlock_drained() wrapper around bdrv_graph_wrunlock() is introduced, which will begin a drained section first. A global variable is used so bdrv_graph_wrunlock() knows if it also needs to end such a drained section. Both the aio_poll call in bdrv_graph_wrlock() and the aio_bh_poll() in bdrv_graph_wrunlock() can re-enter a write-locked section. While for the latter, ending the drain could be moved to before the call, the former requires that the variable is a counter and not just a boolean. Since the wrapper calls bdrv_drain_all_begin(), which must be called with the graph unlocked, mark the wrapper as GRAPH_UNLOCKED too. The switch to the new helpers was generated with the following commands and then manually checked: find . -name '*.c' -exec sed -i -z 's/bdrv_drain_all_begin();\n\s*bdrv_graph_wrlock();/bdrv_graph_wrlock_drained();/g' {} ';' find . -name '*.c' -exec sed -i -z 's/bdrv_graph_wrunlock();\n\s*bdrv_drain_all_end();/bdrv_graph_wrunlock();/g' {} ';' Suggested-by: Kevin Wolf Signed-off-by: Fiona Ebner Message-ID: <20250530151125.955508-25-f.ebner@proxmox.com> [kwolf: Removed redundant GRAPH_UNLOCKED] Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- block/commit.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) (limited to 'block/commit.c') diff --git a/block/commit.c b/block/commit.c index 6c4b736ff8..dc1942483b 100644 --- a/block/commit.c +++ b/block/commit.c @@ -392,8 +392,7 @@ void commit_start(const char *job_id, BlockDriverState *bs, * this is the responsibility of the interface (i.e. whoever calls * commit_start()). */ - bdrv_drain_all_begin(); - bdrv_graph_wrlock(); + bdrv_graph_wrlock_drained(); s->base_overlay = bdrv_find_overlay(top, base); assert(s->base_overlay); @@ -425,21 +424,18 @@ void commit_start(const char *job_id, BlockDriverState *bs, iter_shared_perms, errp); if (ret < 0) { bdrv_graph_wrunlock(); - bdrv_drain_all_end(); goto fail; } } if (bdrv_freeze_backing_chain(commit_top_bs, base, errp) < 0) { bdrv_graph_wrunlock(); - bdrv_drain_all_end(); goto fail; } s->chain_frozen = true; ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp); bdrv_graph_wrunlock(); - bdrv_drain_all_end(); if (ret < 0) { goto fail; -- cgit 1.4.1