linux-kernel - [ 127/184] ext4: lock i_mutex when truncating orphan inodes

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Date:	Tue, 04 Jun 2013 19:23:37 +0200
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	"Theodore Tso" <tytso@....edu>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Willy Tarreau <w@....eu>
Subject: [ 127/184] ext4: lock i_mutex when truncating orphan inodes

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

------------------

From: Theodore Ts'o <tytso@....edu>

commit 721e3eba21e43532e438652dd8f1fcdfce3187e7 upstream.

Commit c278531d39 added a warning when ext4_flush_unwritten_io() is
called without i_mutex being taken.  It had previously not been taken
during orphan cleanup since races weren't possible at that point in
the mount process, but as a result of this c278531d39, we will now see
a kernel WARN_ON in this case.  Take the i_mutex in
ext4_orphan_cleanup() to suppress this warning.

Reported-by: Alexander Beregalov <a.beregalov@...il.com>
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
Reviewed-by: Zheng Liu <wenqing.lz@...bao.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Willy Tarreau <w@....eu>
---
 fs/ext4/super.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 3ce77c5..108515f 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1937,7 +1937,9 @@ static void ext4_orphan_cleanup(struct super_block *sb,
 				__func__, inode->i_ino, inode->i_size);
 			jbd_debug(2, "truncating inode %lu to %lld bytes\n",
 				  inode->i_ino, inode->i_size);
+			mutex_lock(&inode->i_mutex);
 			ext4_truncate(inode);
+			mutex_unlock(&inode->i_mutex);
 			nr_truncates++;
 		} else {
 			ext4_msg(sb, KERN_DEBUG,
-- 
1.7.12.2.21.g234cd45.dirty



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