linux-kernel - Re: [PATCH v3 2/5] fat: allocate persistent inode numbers

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Date:	Tue, 25 Sep 2012 01:16:45 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	"J. Bruce Fields" <bfields@...ldses.org>
Cc:	Namjae Jeon <linkinjeon@...il.com>, akpm@...ux-foundation.org,
	viro@...iv.linux.org.uk, 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 v3 2/5] fat: allocate persistent inode numbers

"J. Bruce Fields" <bfields@...ldses.org> writes:

>> > There is some unclear thing.
>> > When I see first mail, I think maybe you don't want to use i_pos for inode->ino.
>> > FAT allocate inode->ino from i_unique on server side and If NFS client
>> > use i_pos for inode->ino in fat_get_attr, inode numbers on each
>> > client/server will still be mismatched.
>> >
>> > Would you plz give me hint ?
>> 
>> ->i_ino is long. It can't hold i_pos fully on 32bit arch, so we can't
>> use ->i_no to store i_pos, and changing ->i_ino is unnecessary. If
>> getattr() returned i_pos as ino, nobody see ->i_ino anymore except
>> internal of kernel.
>
> The NFS server must always return the same inode number for the same
> filehandle.  To do otherwise is a bug.
>
>> Furthermore I think there is no issue even if server and client didn't
>> have same ino. Because client just uses FH (nfs4 seems to be using
>> stat.ino though).
>
> The client may expose a different inode number to userspace, but it's
> probably the server-provided inode number that it's checking.
>
> (And even if the Linux client didn't currently happen to do that check,
> this would still be a bug.)

In this context, inode number != inode->i_ino, right? It should be
kstat.ino, and in FAT case, it will return i_pos always. Otherwise 64bit
inode number would not work.

So, I think we are doing right thing for now.

Anyway, thanks for your review.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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