On 27.06.2018 16:38, Nikolay Borisov wrote:
> 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 <nborisov@xxxxxxxx>
I'm going to be sending this patch as part of a larger series so you can
ignore it for now.
> ---
> fs/btrfs/qgroup.c | 7 +------
> 1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index 1874a6d2e6f5..3b57dc247fa2 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -2647,9 +2647,6 @@ qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
> 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);
> @@ -2675,10 +2672,8 @@ qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
> 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;
>
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