From a1e7e16ed36b9b059c5ee94e372287418e2dc7bc Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Thu, 4 Dec 2014 15:31:01 +0000 Subject: [PATCH] Btrfs: ensure deletion from pinned_chunks list is protected The call to remove_extent_mapping() actually deletes the extent map from the list it's included in - fs_info->pinned_chunks - and that list is protected by the chunk mutex. Therefore make that call while holding the chunk mutex and remove the redundant list delete call because it's a noop. This fixes an overlook of the patch titled "Btrfs: fix race between fs trimming and block group remove/allocation" following the same obvervation from the patch titled "Btrfs: fix unprotected deletion from pending_chunks list". Signed-off-by: Filipe Manana Signed-off-by: Chris Mason --- fs/btrfs/free-space-cache.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 030847bf7cec..edf32c5bbef1 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -3185,16 +3185,18 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group, spin_unlock(&block_group->lock); + lock_chunks(block_group->fs_info->chunk_root); em_tree = &block_group->fs_info->mapping_tree.map_tree; write_lock(&em_tree->lock); em = lookup_extent_mapping(em_tree, block_group->key.objectid, 1); BUG_ON(!em); /* logic error, can't happen */ + /* + * remove_extent_mapping() will delete us from the pinned_chunks + * list, which is protected by the chunk mutex. + */ remove_extent_mapping(em_tree, em); write_unlock(&em_tree->lock); - - lock_chunks(block_group->fs_info->chunk_root); - list_del_init(&em->list); unlock_chunks(block_group->fs_info->chunk_root); /* once for us and once for the tree */