linux-kernel - [PATCH] [53/223] reiserfs: fix inode mutex

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Date:	Mon, 13 Dec 2010 00:45:50 +0100 (CET)
From:	Andi Kleen <andi@...stfloor.org>
To:	fweisbec@...il.com, jeffm@...e.com, akpm@...ux-foundation.org,
	torvalds@...ux-foundation.org, gregkh@...e.de, ak@...ux.intel.com,
	linux-kernel@...r.kernel.org, stable@...nel.org
Subject: [PATCH] [53/223] reiserfs: fix inode mutex - reiserfs lock misordering

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Frederic Weisbecker <fweisbec@...il.com>

commit da905873effecd1c0166e578bc4b5006f041b18b upstream.

reiserfs_unpack() locks the inode mutex with reiserfs_mutex_lock_safe()
to protect against reiserfs lock dependency.  However this protection
requires to have the reiserfs lock to be locked.

This is the case if reiserfs_unpack() is called by reiserfs_ioctl but
not from reiserfs_quota_on() when it tries to unpack tails of quota
files.

Fix the ordering of the two locks in reiserfs_unpack() to fix this
issue.

Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Reported-by: Markus Gapp <markus.gapp@....net>
Reported-by: Jan Kara <jack@...e.cz>
Cc: Jeff Mahoney <jeffm@...e.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>

---
 fs/reiserfs/ioctl.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

Index: linux/fs/reiserfs/ioctl.c
===================================================================
--- linux.orig/fs/reiserfs/ioctl.c
+++ linux/fs/reiserfs/ioctl.c
@@ -186,12 +186,11 @@ int reiserfs_unpack(struct inode *inode,
 		return 0;
 	}
 
-	/* we need to make sure nobody is changing the file size beneath
-	 ** us
-	 */
-	reiserfs_mutex_lock_safe(&inode->i_mutex, inode->i_sb);
 	depth = reiserfs_write_lock_once(inode->i_sb);
 
+	/* we need to make sure nobody is changing the file size beneath us */
+	reiserfs_mutex_lock_safe(&inode->i_mutex, inode->i_sb);
+
 	write_from = inode->i_size & (blocksize - 1);
 	/* if we are on a block boundary, we are already unpacked.  */
 	if (write_from == 0) {
--
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