Merge branch 'for-chris-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/fdmanana/linux into for-linus-4.4

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:

fs/btrfs/free-space-cache.c

@@ -891,7 +891,7 @@ out:
 		spin_unlock(&block_group->lock);
 		ret = 0;
 
-		btrfs_warn(fs_info, "failed to load free space cache for block group %llu, rebuild it now",
+		btrfs_warn(fs_info, "failed to load free space cache for block group %llu, rebuilding it now",
 			block_group->key.objectid);
 	}
 

fs/btrfs/transaction.c

@@ -274,7 +274,6 @@ loop:
 	cur_trans->num_dirty_bgs = 0;
 	spin_lock_init(&cur_trans->dirty_bgs_lock);
 	INIT_LIST_HEAD(&cur_trans->deleted_bgs);
-	spin_lock_init(&cur_trans->deleted_bgs_lock);
 	spin_lock_init(&cur_trans->dropped_roots_lock);
 	list_add_tail(&cur_trans->list, &fs_info->trans_list);
 	extent_io_tree_init(&cur_trans->dirty_pages,

fs/btrfs/transaction.h

@@ -77,8 +77,8 @@ struct btrfs_transaction {
 	 */
 	struct mutex cache_write_mutex;
 	spinlock_t dirty_bgs_lock;
+	/* Protected by spin lock fs_info->unused_bgs_lock. */
 	struct list_head deleted_bgs;
-	spinlock_t deleted_bgs_lock;
 	spinlock_t dropped_roots_lock;
 	struct btrfs_delayed_ref_root delayed_refs;
 	int aborted;

fs/btrfs/volumes.c

@@ -3548,12 +3548,11 @@ again:
 
 			ret = btrfs_force_chunk_alloc(trans, chunk_root,
 						      BTRFS_BLOCK_GROUP_DATA);
+			btrfs_end_transaction(trans, chunk_root);
 			if (ret < 0) {
 				mutex_unlock(&fs_info->delete_unused_bgs_mutex);
 				goto error;
 			}
-
-			btrfs_end_transaction(trans, chunk_root);
 			chunk_reserved = 1;
 		}