linux-kernel - [PATCH 15/27] fs: Skip atime update on frozen filesystem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 12 Jun 2012 16:20:36 +0200
From:	Jan Kara <jack@...e.cz>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	LKML <linux-kernel@...r.kernel.org>, linux-fsdevel@...e.cz,
	Jan Kara <jack@...e.cz>
Subject: [PATCH 15/27] 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.

BugLink: https://bugs.launchpad.net/bugs/897421
Tested-by: Kamal Mostafa <kamal@...onical.com>
Tested-by: Peter M. Petrakis <peter.petrakis@...onical.com>
Tested-by: Dann Frazier <dann.frazier@...onical.com>
Tested-by: Massimo Morana <massimo.morana@...onical.com>
Signed-off-by: Jan Kara <jack@...e.cz>
---
 fs/inode.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index f23fbd1..433afb3 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1542,9 +1542,11 @@ void touch_atime(struct path *path)
 	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;
 	/*
 	 * File systems can error out when updating inodes if they need to
 	 * allocate new space to modify an inode (such is the case for
@@ -1553,7 +1555,9 @@ void touch_atime(struct path *path)
 	 * so just ignore the return value.
 	 */
 	update_time(inode, &now, S_ATIME);
-	mnt_drop_write(mnt);
+	__mnt_drop_write(mnt);
+skip_update:
+	sb_end_write(inode->i_sb);
 }
 EXPORT_SYMBOL(touch_atime);
 
-- 
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/