X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=fs%2Fbtrfs%2Fextent-tree.c;h=c4661db2b72ae4c412adaaecb7cbc236fbe1e7cf;hb=8f5daf2a49545374b5b433f0ee3ae62fc6e63d4d;hp=4b89680a192338c7a70a4c909e3c4374abe41284;hpb=ff6e0fd55ef24e62efe5c9ab8327312164554250;p=firefly-linux-kernel-4.4.55.git

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 4b89680a1923..c4661db2b72a 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -10480,11 +10480,15 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
 		 * until transaction commit to do the actual discard.
 		 */
 		if (trimming) {
-			WARN_ON(!list_empty(&block_group->bg_list));
-			spin_lock(&trans->transaction->deleted_bgs_lock);
+			spin_lock(&fs_info->unused_bgs_lock);
+			/*
+			 * A concurrent scrub might have added us to the list
+			 * fs_info->unused_bgs, so use a list_move operation
+			 * to add the block group to the deleted_bgs list.
+			 */
 			list_move(&block_group->bg_list,
 				  &trans->transaction->deleted_bgs);
-			spin_unlock(&trans->transaction->deleted_bgs_lock);
+			spin_unlock(&fs_info->unused_bgs_lock);
 			btrfs_get_block_group(block_group);
 		}
 end_trans: