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 <>
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 030847b..edf32c5 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -3185,16 +3185,18 @@
+		lock_chunks(block_group->fs_info->chunk_root);
 		em_tree = &block_group->fs_info->mapping_tree.map_tree;
 		em = lookup_extent_mapping(em_tree, block_group->key.objectid,
 		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);
-		lock_chunks(block_group->fs_info->chunk_root);
-		list_del_init(&em->list);
 		/* once for us and once for the tree */