[XFS] optimize xfs_ichgtime

Port a little optmization from file_update_time to xfs_ichgtime, and only
update the timestamp and mark the inode dirty if the timestamp actually
changes in the timer tick resultion supported by the running kernel.

SGI-PV: 981498

SGI-Modid: xfs-linux-melb:xfs-kern:31827a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/fs/xfs/linux-2.6/xfs_iops.c b/fs/xfs/linux-2.6/xfs_iops.c
index d6947f818f29..0e7ca2155956 100644
--- a/fs/xfs/linux-2.6/xfs_iops.c
+++ b/fs/xfs/linux-2.6/xfs_iops.c
@@ -97,17 +97,23 @@ xfs_ichgtime(
 {
         struct inode    *inode = VFS_I(ip);
         timespec_t      tv;
+        int             sync_it = 0;
 
-        nanotime(&tv);
-        if (flags & XFS_ICHGTIME_MOD) {
+        tv = current_fs_time(inode->i_sb);
+
+        if ((flags & XFS_ICHGTIME_MOD) &&
+            !timespec_equal(&inode->i_mtime, &tv)) {
                 inode->i_mtime = tv;
                 ip->i_d.di_mtime.t_sec = (__int32_t)tv.tv_sec;
                 ip->i_d.di_mtime.t_nsec = (__int32_t)tv.tv_nsec;
+                sync_it = 1;
         }
-        if (flags & XFS_ICHGTIME_CHG) {
+        if ((flags & XFS_ICHGTIME_CHG) &&
+            !timespec_equal(&inode->i_ctime, &tv)) {
                 inode->i_ctime = tv;
                 ip->i_d.di_ctime.t_sec = (__int32_t)tv.tv_sec;
                 ip->i_d.di_ctime.t_nsec = (__int32_t)tv.tv_nsec;
+                sync_it = 1;
         }
 
         /*
@@ -119,10 +125,11 @@ xfs_ichgtime(
          * ensure that the compiler does not reorder the update
          * of i_update_core above the timestamp updates above.
          */
-        SYNCHRONIZE();
-        ip->i_update_core = 1;
-        if (!(inode->i_state & I_NEW))
+        if (sync_it) {
+                SYNCHRONIZE();
+                ip->i_update_core = 1;
                 mark_inode_dirty_sync(inode);
+        }
 }
 
 /*