Btrfs: fix unprotected list move from unused_bgs to deleted_bgs list

[karo-tx-linux.git] / fs / btrfs / extent-tree.c

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 4b89680a192338c7a70a4c909e3c4374abe41284..c4661db2b72ae4c412adaaecb7cbc236fbe1e7cf 100644 (file)
--- 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: