From: Nikolay Borisov Date: Wed, 15 Aug 2018 15:26:56 +0000 (+0300) Subject: btrfs: Remove unnecessary tree locking code in qgroup_rescan_leaf X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=df44971468c1a960cac1ace116e4fa9be50a9479;p=openwrt%2Fstaging%2Fblogic.git btrfs: Remove unnecessary tree locking code in qgroup_rescan_leaf In qgroup_rescan_leaf a copy is made of the target leaf by calling btrfs_clone_extent_buffer. The latter allocates a new buffer and attaches a new set of pages and copies the content of the source buffer. The new scratch buffer is only used to iterate it's items, it's not published anywhere and cannot be accessed by a third party. Hence, it's not necessary to perform any locking on it whatsoever. Furthermore, remove the extra extent_buffer_get call since the new buffer is always allocated with a reference count of 1 which is sufficient here. No functional changes. Signed-off-by: Nikolay Borisov Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index f70825af6438..b53d2e7b938d 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -3104,9 +3104,6 @@ static int qgroup_rescan_leaf(struct btrfs_trans_handle *trans, mutex_unlock(&fs_info->qgroup_rescan_lock); goto out; } - extent_buffer_get(scratch_leaf); - btrfs_tree_read_lock(scratch_leaf); - btrfs_set_lock_blocking_rw(scratch_leaf, BTRFS_READ_LOCK); slot = path->slots[0]; btrfs_release_path(path); mutex_unlock(&fs_info->qgroup_rescan_lock); @@ -3132,10 +3129,8 @@ static int qgroup_rescan_leaf(struct btrfs_trans_handle *trans, goto out; } out: - if (scratch_leaf) { - btrfs_tree_read_unlock_blocking(scratch_leaf); + if (scratch_leaf) free_extent_buffer(scratch_leaf); - } if (done && !ret) { ret = 1;