used_bg          3374 fs/btrfs/extent-tree.c 	struct btrfs_block_group_cache *used_bg = NULL;
used_bg          3378 fs/btrfs/extent-tree.c 		used_bg = cluster->block_group;
used_bg          3379 fs/btrfs/extent-tree.c 		if (!used_bg)
used_bg          3382 fs/btrfs/extent-tree.c 		if (used_bg == block_group)
used_bg          3383 fs/btrfs/extent-tree.c 			return used_bg;
used_bg          3385 fs/btrfs/extent-tree.c 		btrfs_get_block_group(used_bg);
used_bg          3388 fs/btrfs/extent-tree.c 			return used_bg;
used_bg          3390 fs/btrfs/extent-tree.c 		if (down_read_trylock(&used_bg->data_rwsem))
used_bg          3391 fs/btrfs/extent-tree.c 			return used_bg;
used_bg          3396 fs/btrfs/extent-tree.c 		down_read_nested(&used_bg->data_rwsem, SINGLE_DEPTH_NESTING);
used_bg          3399 fs/btrfs/extent-tree.c 		if (used_bg == cluster->block_group)
used_bg          3400 fs/btrfs/extent-tree.c 			return used_bg;
used_bg          3402 fs/btrfs/extent-tree.c 		up_read(&used_bg->data_rwsem);
used_bg          3403 fs/btrfs/extent-tree.c 		btrfs_put_block_group(used_bg);