lkml.org 
[lkml]   [2012]   [Aug]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH 0/4] fat: fix ESTALE errors
From
2012/8/21, J. Bruce Fields <bfields@fieldses.org>:
> On Mon, Aug 20, 2012 at 01:19:51PM +0900, Namjae Jeon wrote:
>> 2012/8/18, OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>:
>> > Al Viro <viro@ZenIV.linux.org.uk> writes:
>> >
>> >> On Sat, Aug 18, 2012 at 05:41:39AM -0400, Namjae Jeon wrote:
>> >>> From: Namjae Jeon <namjae.jeon@samsung.com>
>> >>>
>> >>> This patch-set eliminates the client side ESTALE errors when
>> >>> a FAT partition exported over NFS has its dentries evicted
>> >>> from the cache.
>> >>>
>> >>> One of the reasons for this error is lack of permanent inode
>> >>> numbers on FAT which makes it difficult to construct persistent
>> >>> file handles.This can be overcome by using the on-disk location
>> >>> of the directory entries (i_pos) as the inode number.
>> >>
>> >> The hell it can. You've just made them unstable on rename(2).
>> >
>> > As more hint. We can't use i_pos as the inode number.
>> >
>> > E.g. inode is unlinked but is still opened (orphaned inode), the dir
>> > entry is free and you can create the inode on same i_pos. After that,
>> > both inodes have same i_pos (so inode number).
>> >
>> > Thanks.
>> Hi. Ogawa.
>> Thanks for specific explanation. I will check it.
>
Hi Bruce.
> Fo somebody that knows more about fat than me--is there really any hope
> of making it play well with nfs?

I think that this patch is only solution to fix estale issue from
inode cache eviction.
In case FAT - it makes use of iunique() to get unique inode number
-which is just based upon getting an incremented value from unique
counter variable. So, there is no way to reconstruct the inode based
upon inode numbers - like in case of other filesystems

We can check it easily like this.

1. ls -al /directory on nfs client.
2. echo 3 > /proc/sys/vm/drop_caches
3. ls -al /directory on nfs client again. estale error will be occurred.

There is no estale issue from reclaim with this patch.

And.. Hi Ogawa.
I checked other filesystem about unlink - inode issue. but I found
Ext4 have same issue.
Although other filesysm is having this issue, Can we think It could be
only FAT issue ?
>
> --b.
>


\
 
 \ /
  Last update: 2012-08-21 08:01    [W:0.181 / U:0.756 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site