dmonakhov@openvz.org writes:

> Jan Kara <jack@suse.cz> writes:
>
>> On Tue 30-03-10 18:25:28, Dmitry Monakhov wrote:
>>> We already has per-dquot sanity checks, but with per-inode checks
>>> quota leakage investigation becomes much easier.
>>> 
>>> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
>>> ---
>>>  fs/quota/dquot.c |    4 ++++
>>>  1 files changed, 4 insertions(+), 0 deletions(-)
>>> 
>>> diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
>>> index e0b870f..4db57b7 100644
>>> --- a/fs/quota/dquot.c
>>> +++ b/fs/quota/dquot.c
>>> @@ -1428,6 +1428,8 @@ EXPORT_SYMBOL(inode_add_rsv_space);
>>>  void inode_claim_rsv_space(struct inode *inode, qsize_t number)
>>>  {
>>>  	spin_lock(&inode->i_lock);
>>> +	if (*inode_reserved_space(inode) < number)
>>> +		WARN_ON_ONCE(1);
>>   Maybe just: WARN_ON_ONCE(*inode_reserved_space(inode) < number)
Ohh. While writing testcase for automatic-quota consistency check.
I've failed to reliably detect condition where quota goes inconsistent.
And it appears to be not what easy. We have hided real problems too deeply.
The only reliable way is to grep dmesg for hard-coded "fs/quota/dquot.c"
string which produced by WARN_ON_ONCE.

After some thoughts (sometimes it happens with me too)
i'm think what it is reasonable rewrite all quota error messages logic.
Make it similar to ext4
quota_error(...) {
   printk("QUOTA error (dev:%s)", ...);
   handle_quota_error(sb) /* let sb to know what quota is corrupted */
}
quota_warn(...) {
   printk("QUOTA warn (dev:%s)", ...);
}
In fact it is very important to let filesystem to now that it's quota
is corrupted(quota == fs-metadata). It may set fsck_needed flag on
super block for later correction.
So please ignore this patch for now. I'll prepare another one which
redesign error conditions handling logic.

BTW: I've attached my testcase. I hope it will be useful for you.
It able to catch quota inconsistency caused by incorrect symlink
handling, but it is not reliable for writepage/fallocate bug in ext4.