xfs: log timestamp updates

Timestamps on regular files are the last metadata that XFS does not update
transactionally.  Now that we use the delaylog mode exclusively and made
the log scode scale extremly well there is no need to bypass that code for
timestamp updates.  Logging all updates allows to drop a lot of code, and
will allow for further performance improvements later on.

Note that this patch drops optimized handling of fdatasync - it will be
added back in a separate commit.

Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index 751e94f..9720c54 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -62,7 +62,6 @@
 {
 	struct xfs_icdinode	*dic;		/* dinode core info pointer */
 	struct xfs_inode	*ip;		/* incore inode pointer */
-	struct inode		*inode;
 	struct xfs_bstat	*buf;		/* return buffer */
 	int			error = 0;	/* error value */
 
@@ -86,7 +85,6 @@
 	ASSERT(ip->i_imap.im_blkno != 0);
 
 	dic = &ip->i_d;
-	inode = VFS_I(ip);
 
 	/* xfs_iget returns the following without needing
 	 * further change.
@@ -99,19 +97,12 @@
 	buf->bs_uid = dic->di_uid;
 	buf->bs_gid = dic->di_gid;
 	buf->bs_size = dic->di_size;
-
-	/*
-	 * We need to read the timestamps from the Linux inode because
-	 * the VFS keeps writing directly into the inode structure instead
-	 * of telling us about the updates.
-	 */
-	buf->bs_atime.tv_sec = inode->i_atime.tv_sec;
-	buf->bs_atime.tv_nsec = inode->i_atime.tv_nsec;
-	buf->bs_mtime.tv_sec = inode->i_mtime.tv_sec;
-	buf->bs_mtime.tv_nsec = inode->i_mtime.tv_nsec;
-	buf->bs_ctime.tv_sec = inode->i_ctime.tv_sec;
-	buf->bs_ctime.tv_nsec = inode->i_ctime.tv_nsec;
-
+	buf->bs_atime.tv_sec = dic->di_atime.t_sec;
+	buf->bs_atime.tv_nsec = dic->di_atime.t_nsec;
+	buf->bs_mtime.tv_sec = dic->di_mtime.t_sec;
+	buf->bs_mtime.tv_nsec = dic->di_mtime.t_nsec;
+	buf->bs_ctime.tv_sec = dic->di_ctime.t_sec;
+	buf->bs_ctime.tv_nsec = dic->di_ctime.t_nsec;
 	buf->bs_xflags = xfs_ip2xflags(ip);
 	buf->bs_extsize = dic->di_extsize << mp->m_sb.sb_blocklog;
 	buf->bs_extents = dic->di_nextents;