linux-kernel - Re: [PATCH v2 1/5] fat: allocate persistent inode numbers

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Date:	Wed, 12 Sep 2012 00:47:22 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	"Steven J. Magnani" <steve@...idescorp.com>,
	Al Viro <viro@...iv.linux.org.uk>, akpm@...ux-foundation.org,
	bfields@...ldses.org, linux-kernel@...r.kernel.org,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Ravishankar N <ravi.n1@...sung.com>,
	Amit Sahrawat <a.sahrawat@...sung.com>
Subject: Re: [PATCH v2 1/5] fat: allocate persistent inode numbers

Namjae Jeon <linkinjeon@...il.com> writes:

>>> I think that it is unfixable because we can not know i_pos of inode
>>> changed by rename.
>>> And even though we know it, there is no rebuild inode routine in -mm.
>>> And It even can not fix in our patches.
>>
>>>> And are you tried https://lkml.org/lkml/2012/6/29/381 patches? It sounds
>>>> like to improve performance by enabling lookupcache.
>>> We checked this patches when facing estale issue in -mm.
>>> But It is no use, these patches just retry system call one more when
>>> estale error.
>>
>> What happens if client retried from lookup() after -ESTALE? (client NFS
>> doesn't have the name of entry anymore?)
> Need to rebuild inode routine because inode cache is already evicted on Server.
>>
>> I'm assuming the retry means - it restarts from building the NFS file
>> handle. I might be just wrong here though.
> As I remember, just retry in VFS of NFS client..I heard this patch is
> needed for
> a very specific set of circumstances where an entry goes stale once
> between the lookup and the actual operation(s).
> It is not related with current issues(inode cache eviction on server).

Supposing, the server/client state is after cold boot, and client try to
rename at first without any cache on client/server.

Even if this state, does the server return ESTALE? If it doesn't return
ESTALE, I can't understand why it is really unfixable.

If it returns ESTALE, why does it return? I'm assuming the previous code
path is the cached FH path.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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