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

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Date:	Mon, 24 Sep 2012 21:32:00 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	akpm@...ux-foundation.org, bfields@...ldses.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

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

> 2012/9/24, OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>:
>> Namjae Jeon <linkinjeon@...il.com> writes:
>>
>>>> I see. fileid seems to be stat.ino on nfsd4. inode->i_ino is actually
>>>> just a hash key of inode hash (exception is only in audit, iirc).
>>>>
>>>> So, what happens if we set "stat->ino = i_pos" on fat_getattr().
>>>>
>>>> int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct
>>>> kstat
>>>> *stat)
>>>> {
>>>> 	struct inode *inode = dentry->d_inode;
>>>> 	generic_fillattr(inode, stat);
>>>> 	stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
>>>> 	if (opts->nfs == FAT_NFS_LIMITED) {
>>>> 		/* Use i_pos for ino. This is used as fileid of nfs. */
>>>> 		stat->ino = MSDOS_SB(inode->i_sb)->i_pos;
>>
>> 		stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
>>
>> Ouch, I forgot to use fat_i_pos_read().
>>
> 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.

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