linux-kernel - [PATCH 17/19] xfs: avoid setting XFS_ILOG_CORE if i

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Date:   Wed, 13 Dec 2017 09:20:15 -0500
From:   Jeff Layton <jlayton@...nel.org>
To:     linux-fsdevel@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, hch@....de, neilb@...e.de,
        bfields@...ldses.org, amir73il@...il.com, jack@...e.de,
        viro@...iv.linux.org.uk
Subject: [PATCH 17/19] xfs: avoid setting XFS_ILOG_CORE if i_version doesn't need incrementing

From: Jeff Layton <jlayton@...hat.com>

If XFS_ILOG_CORE is already set then go ahead and increment it.

Signed-off-by: Jeff Layton <jlayton@...hat.com>
---
 fs/xfs/xfs_trans_inode.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/fs/xfs/xfs_trans_inode.c b/fs/xfs/xfs_trans_inode.c
index b41a92d18140..18635c5b5dc6 100644
--- a/fs/xfs/xfs_trans_inode.c
+++ b/fs/xfs/xfs_trans_inode.c
@@ -110,15 +110,17 @@ xfs_trans_log_inode(
 
 	/*
 	 * First time we log the inode in a transaction, bump the inode change
-	 * counter if it is configured for this to occur. We don't use
-	 * inode_inc_version() because there is no need for extra locking around
-	 * i_version as we already hold the inode locked exclusively for
-	 * metadata modification.
+	 * counter if it is configured for this to occur. While we have the
+	 * inode locked exclusively for metadata modification, we can usually
+	 * avoid setting XFS_ILOG_CORE if no one has queried the value since
+	 * the last time it was incremented. If we have XFS_ILOG_CORE already
+	 * set however, then go ahead and bump the i_version counter
+	 * unconditionally.
 	 */
 	if (!(ip->i_itemp->ili_item.li_desc->lid_flags & XFS_LID_DIRTY) &&
 	    IS_I_VERSION(VFS_I(ip))) {
-		inode_inc_iversion(VFS_I(ip));
-		flags |= XFS_ILOG_CORE;
+		if (inode_maybe_inc_iversion(VFS_I(ip), flags & XFS_ILOG_CORE))
+			flags |= XFS_ILOG_CORE;
 	}
 
 	tp->t_flags |= XFS_TRANS_DIRTY;
-- 
2.14.3