Re: [PATCH] xfs: avoid shared rmap operations for attr fork extents

Chandan Babu R
2020-09-24T04:44:23Z

On Wednesday 23 September 2020 11:53:40 PM IST Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> During code review, I noticed that the rmap code uses the (slower)
> shared mappings rmap functions for any extent of a reflinked file, even
> if those extents are for the attr fork, which doesn't support sharing.
> We can speed up rmap a tiny bit by optimizing out this case.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

Looks good to me.

Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

> ---
> fs/xfs/libxfs/xfs_rmap.c | 27 ++++++++++++++++++---------
> 1 file changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
> index 27c39268c31f..340c83f76c80 100644
> --- a/fs/xfs/libxfs/xfs_rmap.c
> +++ b/fs/xfs/libxfs/xfs_rmap.c
> @@ -2505,12 +2505,15 @@ xfs_rmap_map_extent(
> int whichfork,
> struct xfs_bmbt_irec *PREV)
> {
> + enum xfs_rmap_intent_type type = XFS_RMAP_MAP;
> +
> if (!xfs_rmap_update_is_needed(tp->t_mountp, whichfork))
> return;
>
> - __xfs_rmap_add(tp, xfs_is_reflink_inode(ip) ?
> - XFS_RMAP_MAP_SHARED : XFS_RMAP_MAP, ip->i_ino,
> - whichfork, PREV);
> + if (whichfork != XFS_ATTR_FORK && xfs_is_reflink_inode(ip))
> + type = XFS_RMAP_MAP_SHARED;
> +
> + __xfs_rmap_add(tp, type, ip->i_ino, whichfork, PREV);
> }
>
> /* Unmap an extent out of a file. */
> @@ -2521,12 +2524,15 @@ xfs_rmap_unmap_extent(
> int whichfork,
> struct xfs_bmbt_irec *PREV)
> {
> + enum xfs_rmap_intent_type type = XFS_RMAP_UNMAP;
> +
> if (!xfs_rmap_update_is_needed(tp->t_mountp, whichfork))
> return;
>
> - __xfs_rmap_add(tp, xfs_is_reflink_inode(ip) ?
> - XFS_RMAP_UNMAP_SHARED : XFS_RMAP_UNMAP, ip->i_ino,
> - whichfork, PREV);
> + if (whichfork != XFS_ATTR_FORK && xfs_is_reflink_inode(ip))
> + type = XFS_RMAP_UNMAP_SHARED;
> +
> + __xfs_rmap_add(tp, type, ip->i_ino, whichfork, PREV);
> }
>
> /*
> @@ -2543,12 +2549,15 @@ xfs_rmap_convert_extent(
> int whichfork,
> struct xfs_bmbt_irec *PREV)
> {
> + enum xfs_rmap_intent_type type = XFS_RMAP_CONVERT;
> +
> if (!xfs_rmap_update_is_needed(mp, whichfork))
> return;
>
> - __xfs_rmap_add(tp, xfs_is_reflink_inode(ip) ?
> - XFS_RMAP_CONVERT_SHARED : XFS_RMAP_CONVERT, ip->i_ino,
> - whichfork, PREV);
> + if (whichfork != XFS_ATTR_FORK && xfs_is_reflink_inode(ip))
> + type = XFS_RMAP_CONVERT_SHARED;
> +
> + __xfs_rmap_add(tp, type, ip->i_ino, whichfork, PREV);
> }
>
> /* Schedule the creation of an rmap for non-file data. */
>

--
chandan