linux-kernel - [PATCH 08/19] fs: Skip atime update on frozen filesystem

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Message-Id: <1330963277-26336-9-git-send-email-jack@suse.cz>
Date:	Mon,  5 Mar 2012 17:01:06 +0100
From:	Jan Kara <jack@...e.cz>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	linux-fsdevel@...r.kernel.org, Al Viro <viro@...IV.linux.org.uk>,
	Christoph Hellwig <hch@...radead.org>, dchinner@...hat.com,
	sandeen@...hat.com, Kamal Mostafa <kamal@...onical.com>,
	Jan Kara <jack@...e.cz>
Subject: [PATCH 08/19] fs: Skip atime update on frozen filesystem

It is unexpected to block reading of frozen filesystem because of atime update.
Also handling blocking on frozen filesystem because of atime update would make
locking more complex than it already is. So just skip atime update when
filesystem is frozen like we skip it when filesystem is remounted read-only.

Signed-off-by: Jan Kara <jack@...e.cz>
---
 fs/inode.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index 095828c..ff3b385 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1535,12 +1535,17 @@ void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
 	if (timespec_equal(&inode->i_atime, &now))
 		return;
 
-	if (mnt_want_write(mnt))
+	if (!sb_start_write_trylock(inode->i_sb))
 		return;
 
+	if (__mnt_want_write(mnt))
+		goto skip_update;
+
 	inode->i_atime = now;
 	mark_inode_dirty_sync(inode);
-	mnt_drop_write(mnt);
+	__mnt_drop_write(mnt);
+skip_update:
+	sb_end_write(inode->i_sb);
 }
 EXPORT_SYMBOL(touch_atime);
 
-- 
1.7.1

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