warn on lookup_one_length/vfs_quota_on_mount

warn on lookup_one_length/vfs_quota_on_mount

[Bastien ROUCARIES]

Dear developer,

I get the following warm on my reiserfs disk with quota enabled at
boot (each boot) see
http://www.kerneloops.org/raw.php?rawid=937752&msgid=
*lookup_one_len
? lookup_one_len
? lookup_one_len
? warn_slowpath_common
? lookup_one_len
? vfs_quota_on_mount
? finish_unfinished
? reiserfs_remount
? __filemap_fdatawrite_range
? do_remount_sb
? do_mount
? sys_mount
? system_call_fastpath

But it seems a generic bug in the quota layer due to:
http://www.kerneloops.org/oops.php?number=799645
http://www.kerneloops.org/oops.php?number=700122

Thank you

Bastien

Re: warn on lookup_one_length/vfs_quota_on_mount

[Jan Kara]

  Hi,

On Thu 12-11-09 08:29:06, Bastien ROUCARIES wrote:
> I get the following warm on my reiserfs disk with quota enabled at
> boot (each boot) see
> http://www.kerneloops.org/raw.php?rawid=937752&msgid=
> *lookup_one_len
> ? lookup_one_len
> ? lookup_one_len
> ? warn_slowpath_common
> ? lookup_one_len
> ? vfs_quota_on_mount
> ? finish_unfinished
> ? reiserfs_remount
> ? __filemap_fdatawrite_range
> ? do_remount_sb
> ? do_mount
> ? sys_mount
> ? system_call_fastpath
> 
> But it seems a generic bug in the quota layer due to:
> http://www.kerneloops.org/oops.php?number=799645
> http://www.kerneloops.org/oops.php?number=700122
  OK, this shouldn't lead to any real bug (since we look them up during
filesystem mount or remount read-write when noone can mess with the root
directory). But it's probably good to silence the warning by proper locking
anyway. I'll do it. Thanks for the report!

								Honza

-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

Re: warn on lookup_one_length/vfs_quota_on_mount

[Jan Kara]

[-- Attachment #1: Type: text/plain, Size: 1094 bytes --]

  Hello,

On Thu 12-11-09 13:42:38, Jan Kara wrote:
> On Thu 12-11-09 08:29:06, Bastien ROUCARIES wrote:
> > I get the following warm on my reiserfs disk with quota enabled at
> > boot (each boot) see
> > http://www.kerneloops.org/raw.php?rawid=937752&msgid=
> > *lookup_one_len
> > ? lookup_one_len
> > ? lookup_one_len
> > ? warn_slowpath_common
> > ? lookup_one_len
> > ? vfs_quota_on_mount
> > ? finish_unfinished
> > ? reiserfs_remount
> > ? __filemap_fdatawrite_range
> > ? do_remount_sb
> > ? do_mount
> > ? sys_mount
> > ? system_call_fastpath
> > 
> > But it seems a generic bug in the quota layer due to:
> > http://www.kerneloops.org/oops.php?number=799645
> > http://www.kerneloops.org/oops.php?number=700122
>   OK, this shouldn't lead to any real bug (since we look them up during
> filesystem mount or remount read-write when noone can mess with the root
> directory). But it's probably good to silence the warning by proper locking
> anyway. I'll do it. Thanks for the report!
  Attached patch fixes the warning for me.

									Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

[-- Attachment #2: 0001-quota-Fix-WARN_ON-in-lookup_one_len.patch --]
[-- Type: text/x-patch, Size: 1213 bytes --]

>From 1422c40784979ee85aa0f74655fc6e627ddbb1c0 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Thu, 12 Nov 2009 15:42:08 +0100
Subject: [PATCH] quota: Fix WARN_ON in lookup_one_len

We should hold i_mutex when looking up quota files for journaled quotas,
otherwise a WARN_ON in lookup_one_len triggers. The fact that we didn't
hold i_mutex previously probably could not lead to a real bug since the
filesystem is just being mounted / remounted read-write and thus the
root directory cannot change anyway but it's definitely cleaner with
i_mutex.

Reported-by: Bastien ROUCARIES <roucaries.bastien@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/quota/dquot.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 39b49c4..aa97df1 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2233,7 +2233,9 @@ int vfs_quota_on_mount(struct super_block *sb, char *qf_name,
 	struct dentry *dentry;
 	int error;
 
+	mutex_lock(&sb->s_root->d_inode->i_mutex);
 	dentry = lookup_one_len(qf_name, sb->s_root, strlen(qf_name));
+	mutex_unlock(&sb->s_root->d_inode->i_mutex);
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
 
-- 
1.6.0.2

Re: warn on lookup_one_length/vfs_quota_on_mount

[Bastien ROUCARIES]

On Thu, Nov 12, 2009 at 5:20 PM, Jan Kara <jack@suse.cz> wrote:
>  Hello,
>
> On Thu 12-11-09 13:42:38, Jan Kara wrote:
>> On Thu 12-11-09 08:29:06, Bastien ROUCARIES wrote:
>> > I get the following warm on my reiserfs disk with quota enabled at
>> > boot (each boot) see
>> > http://www.kerneloops.org/raw.php?rawid=937752&msgid=
>> > *lookup_one_len
>> > ? lookup_one_len
>> > ? lookup_one_len
>> > ? warn_slowpath_common
>> > ? lookup_one_len
>> > ? vfs_quota_on_mount
>> > ? finish_unfinished
>> > ? reiserfs_remount
>> > ? __filemap_fdatawrite_range
>> > ? do_remount_sb
>> > ? do_mount
>> > ? sys_mount
>> > ? system_call_fastpath
[...]
>  Attached patch fixes the warning for me.

Sorry for the late reply. Fix for me also

thanks

bastien