From: Filipe Manana Date: Thu, 3 Feb 2022 15:36:45 +0000 (+0000) Subject: btrfs: assert we have a write lock when removing and replacing extent maps X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=6d3b050efa079f5bc4d5e2a8f37f0dc0345a2096;p=linux.git btrfs: assert we have a write lock when removing and replacing extent maps Removing or replacing an extent map requires holding a write lock on the extent map's tree. We currently do that everywhere, except in one of the self tests, where it's harmless since there's no concurrency. In order to catch possible races in the future, assert that we are holding a write lock on the extent map tree before removing or replacing an extent map in the tree, and update the self test to obtain a write lock before removing extent maps. Reviewed-by: Johannes Thumshirn Signed-off-by: Filipe Manana Signed-off-by: David Sterba --- diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c index c28ceddefae42..6fee14ce2e6b1 100644 --- a/fs/btrfs/extent_map.c +++ b/fs/btrfs/extent_map.c @@ -492,6 +492,8 @@ struct extent_map *search_extent_mapping(struct extent_map_tree *tree, */ void remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em) { + lockdep_assert_held_write(&tree->lock); + WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags)); rb_erase_cached(&em->rb_node, &tree->map); if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags)) @@ -506,6 +508,8 @@ void replace_extent_mapping(struct extent_map_tree *tree, struct extent_map *new, int modified) { + lockdep_assert_held_write(&tree->lock); + WARN_ON(test_bit(EXTENT_FLAG_PINNED, &cur->flags)); ASSERT(extent_map_in_tree(cur)); if (!test_bit(EXTENT_FLAG_LOGGING, &cur->flags)) diff --git a/fs/btrfs/tests/extent-map-tests.c b/fs/btrfs/tests/extent-map-tests.c index 319fed82d741f..c5b3a631bf4fb 100644 --- a/fs/btrfs/tests/extent-map-tests.c +++ b/fs/btrfs/tests/extent-map-tests.c @@ -15,6 +15,7 @@ static void free_extent_map_tree(struct extent_map_tree *em_tree) struct extent_map *em; struct rb_node *node; + write_lock(&em_tree->lock); while (!RB_EMPTY_ROOT(&em_tree->map.rb_root)) { node = rb_first_cached(&em_tree->map); em = rb_entry(node, struct extent_map, rb_node); @@ -32,6 +33,7 @@ static void free_extent_map_tree(struct extent_map_tree *em_tree) #endif free_extent_map(em); } + write_unlock(&em_tree->lock); } /*