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>

1 files changed, 14 insertions, 69 deletions

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 7e5bc87..78d8b02 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -163,7 +163,6 @@ xfs_file_fsync(
 	struct inode		*inode = file->f_mapping->host;
 	struct xfs_inode	*ip = XFS_I(inode);
 	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_trans	*tp;
 	int			error = 0;
 	int			log_flushed = 0;
 	xfs_lsn_t		lsn = 0;
@@ -194,75 +193,15 @@ xfs_file_fsync(
 	}
 
 	/*
-	 * We always need to make sure that the required inode state is safe on
-	 * disk.  The inode might be clean but we still might need to force the
-	 * log because of committed transactions that haven't hit the disk yet.
-	 * Likewise, there could be unflushed non-transactional changes to the
-	 * inode core that have to go to disk and this requires us to issue
-	 * a synchronous transaction to capture these changes correctly.
-	 *
-	 * This code relies on the assumption that if the i_update_core field
-	 * of the inode is clear and the inode is unpinned then it is clean
-	 * and no action is required.
+	 * All metadata updates are logged, which means that we just have
+	 * to flush the log up to the latest LSN that touched the inode.
 	 */
 	xfs_ilock(ip, XFS_ILOCK_SHARED);
-
-	/*
-	 * First check if the VFS inode is marked dirty.  All the dirtying
-	 * of non-transactional updates do not go through mark_inode_dirty*,
-	 * which allows us to distinguish between pure timestamp updates
-	 * and i_size updates which need to be caught for fdatasync.
-	 * After that also check for the dirty state in the XFS inode, which
-	 * might gets cleared when the inode gets written out via the AIL
-	 * or xfs_iflush_cluster.
-	 */
-	if (((inode->i_state & I_DIRTY_DATASYNC) ||
-	    ((inode->i_state & I_DIRTY_SYNC) && !datasync)) &&
-	    ip->i_update_core) {
-		/*
-		 * Kick off a transaction to log the inode core to get the
-		 * updates.  The sync transaction will also force the log.
-		 */
-		xfs_iunlock(ip, XFS_ILOCK_SHARED);
-		tp = xfs_trans_alloc(mp, XFS_TRANS_FSYNC_TS);
-		error = xfs_trans_reserve(tp, 0,
-				XFS_FSYNC_TS_LOG_RES(mp), 0, 0, 0);
-		if (error) {
-			xfs_trans_cancel(tp, 0);
-			return -error;
-		}
-		xfs_ilock(ip, XFS_ILOCK_EXCL);
-
-		/*
-		 * Note - it's possible that we might have pushed ourselves out
-		 * of the way during trans_reserve which would flush the inode.
-		 * But there's no guarantee that the inode buffer has actually
-		 * gone out yet (it's delwri).	Plus the buffer could be pinned
-		 * anyway if it's part of an inode in another recent
-		 * transaction.	 So we play it safe and fire off the
-		 * transaction anyway.
-		 */
-		xfs_trans_ijoin(tp, ip, 0);
-		xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
-		error = xfs_trans_commit(tp, 0);
-
+	if (xfs_ipincount(ip))
 		lsn = ip->i_itemp->ili_last_lsn;
-		xfs_iunlock(ip, XFS_ILOCK_EXCL);
-	} else {
-		/*
-		 * Timestamps/size haven't changed since last inode flush or
-		 * inode transaction commit.  That means either nothing got
-		 * written or a transaction committed which caught the updates.
-		 * If the latter happened and the transaction hasn't hit the
-		 * disk yet, the inode will be still be pinned.  If it is,
-		 * force the log.
-		 */
-		if (xfs_ipincount(ip))
-			lsn = ip->i_itemp->ili_last_lsn;
-		xfs_iunlock(ip, XFS_ILOCK_SHARED);
-	}
+	xfs_iunlock(ip, XFS_ILOCK_SHARED);
 
-	if (!error && lsn)
+	if (lsn)
 		error = _xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, &log_flushed);
 
 	/*
@@ -659,9 +598,6 @@ restart:
 		return error;
 	}
 
-	if (likely(!(file->f_mode & FMODE_NOCMTIME)))
-		file_update_time(file);
-
 	/*
 	 * If the offset is beyond the size of the file, we need to zero any
 	 * blocks that fall between the existing EOF and the start of this
@@ -685,6 +621,15 @@ restart:
 		return error;
 
 	/*
+	 * Updating the timestamps will grab the ilock again from
+	 * xfs_fs_dirty_inode, so we have to call it after dropping the
+	 * lock above.  Eventually we should look into a way to avoid
+	 * the pointless lock roundtrip.
+	 */
+	if (likely(!(file->f_mode & FMODE_NOCMTIME)))
+		file_update_time(file);
+
+	/*
 	 * If we're writing the file then make sure to clear the setuid and
 	 * setgid bits if the process is not being run by root.  This keeps
 	 * people from modifying setuid and setgid binaries.