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

Darrick J. Wong
2020-09-23T18:23:44Z

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>
---
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. */