linux-kernel - Re: [PATCH 2/2] fat (exportfs): reconnect file handles to evicted inodes/dentries

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Date:	Thu, 05 Jul 2012 12:59:01 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	"Steve Magnani" <steve@...idescorp.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] fat (exportfs): reconnect file handles to evicted inodes/dentries

"Steve Magnani" <steve@...idescorp.com> writes:

>> And can you add explanation the test of this? What were tested?
>
> I set up a memory-limited virtual machine with a 2 GB FAT partition 
> containing a kernel tree (~770 MB, ~40000 files, 9 levels) and did some 
> 'cp -r' and 'ls -lR' operations on it, some overlapping, some not.

Sounds good. It would be useful to add to changelog.

>> Please don't add new lock_super() usage if it is not necessary. Almost
>> all of lock_super() just replaced lock_kernel() usage. It rather should
>> be removed in future.  Probably, this should use inode->i_mutex
>> instead.
>
> I will look into this. My concern was freezing the filesystem while we 
> walk the on-disk structures. Also I developed this patch against 2.6.35 
> (the Bad Old BKL days) and ported it forward to 3.5.

I see.

>> BTW, the above issue is same with all of directory read.
>> 
>> And although this is using i_pos, is there no possibility to be passed
>> the detached inode (i.e. open but unlinked inode, i_pos == 0)?
>
> It is possible, that's why I added code to fall back to using logstart.
>
> I may yet rip out the get_name code. The testing I did before posting the 
> patch seemed to indicate that it was needed - I saw ESTALE errors without 
> get_name support that I did not see with it present. But I've been 
> digging into this some more and I think that was just a coincidence; 
> probably I just generated more extreme memory pressure when testing 
> without get_name. I should know more tomorrow.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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