linux-kernel - Re: [pnfs] [GIT BISECT] first bad commit: 1f36f774 Switch !O_CREAT case to use of do

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Date:	Wed, 24 Mar 2010 19:32:28 +0200
From:	Boaz Harrosh <bharrosh@...asas.com>
To:	Al Viro <viro@...IV.linux.org.uk>
CC:	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	pNFS Mailing List <pnfs@...ux-nfs.org>,
	"J. Bruce Fields" <bfields@...i.umich.edu>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [pnfs] [GIT BISECT] first bad commit: 1f36f774 Switch !O_CREAT
 case to use of do_last()

On 03/24/2010 07:15 PM, Boaz Harrosh wrote:
> On 03/24/2010 06:39 PM, Al Viro wrote:
>> On Wed, Mar 24, 2010 at 06:10:52PM +0200, Boaz Harrosh wrote:
>>> On 03/24/2010 06:07 PM, Al Viro wrote:
>>>> On Wed, Mar 24, 2010 at 06:04:56PM +0200, Boaz Harrosh wrote:
>>>>>> Bloody impressive...  Does that happen to underlying fs or to what you
>>>>>> are seeing via NFS?
>>>>>
>>>>> Only via NFS. All local access is fine.
>>>>>
>>>>> After the corruption above I can cd to the local mount cp a fresh copy
>>>>> of .git/index file and play around just fine.
>>>>> Once I return to the NFS mounted directory, a git status will do it.
>>>>> It does not matter if caches are cold (Takes a long time) or hot it happens
>>>>> every time.
>>>>>
>>>>> Weird I know, I'm playing some more with it as we speak
>>>>
>>>> What happens if you export to box running older kernel *or* from box
>>>> running older kernel?  IOW, is that nfsd or nfs client getting unhappy?
>>>> I'd suspect the latter, but...
>>>
>>>
>>> Good question, I'm just getting to that because currently it's all
>>> over localhost (same kernel, BTW inside a UML)
>>>
>>> I will try what you said. Please through any other tests on me, if needed.
>>
> 
> As you suspected old-server+new-client fails. any-thing+old-client is
> fine. (two separate machines this time)
> 
>> Very interesting...  Just to see which path we are hitting: add
>> 	if (IS_ERR(nd->intent.open.file))
>> 		printk("foo: %s", pathname);
>> right after
>>                 error = do_lookup(nd, &nd->last, path);
>>                 if (error)
>>                         goto exit;
>> in fs/namei.c:do_last() and see whether we are hitting it or not on objects
>> that get corrupted.
> 
> Sorry was busy shifting setups, didn't see your mail, will do that next ...
> 
> Thanks
> Boaz


Below is what I changed. (I hope its what you meant)
It does not get hit, just that git corruption as before but I don't see the prints.
I'll try running with nfs dbg-prints on see what it does around the time gits complains

Boaz

---
diff --git a/fs/namei.c b/fs/namei.c
index 1c0fca6..d1c96f0 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1650,6 +1650,12 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
 		error = do_lookup(nd, &nd->last, path);
 		if (error)
 			goto exit;
+
+		if (IS_ERR(nd->intent.open.file)) {
+			printk(KERN_ERR "foo: %s", pathname);
+			WARN_ON(1);
+		}
+
 		error = -ENOENT;
 		if (!path->dentry->d_inode)
 			goto exit_dput;


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