lkml.org 
[lkml]   [2002]   [Jan]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [BUG] symlink problem with knfsd and reiserfs
Hans-Peter Jansen writes:
> On Tuesday, 15. January 2002 17:47, Nikita Danilov wrote:
> > Trond Myklebust writes:
> > > On Tuesday 15. January 2002 16:27, Nikita Danilov wrote:
> > > > In reiserfs there is no static inode table, so we keep global
> > > > generation counter in a super block which is incremented on each inode
> > > > deletion, this generation is stored in the new inodes. Not that good
> > > > as per-inode generation, but we cannot do better without changing disk
> > > > format.
> > >
> > > Am I right in assuming that you therefore cannot check that the
> > > filehandle is stale if the client presents you with the filehandle of
> > > the 'old' inode (prior to deletion)?
> > > However if the client compares the 'old' and 'new' filehandle, it will
> > > find them to be different?
> >
> > Sorry for being vague. Reiserfs keeps global "inode generation counter"
> > ->s_inode_generation in a super block. This counter is incremented each
> > time reiserfs inode is being deleted on a disk. When new inode is
> > created, current value of ->s_inode_generation is stored in inode's
> > on-disk representation. Inode number (objectid in reiserfs parlance) is
> > reusable once inode was deleted. The same pair (i_ino, i_generation) can
> > be assigned to different inode only after ->s_inode_generation
> > overflows, which requires 2**32 file deletions.
>
> Except it's in 3.5 format, which requires one deletion then?

In the same directory, yes.

>
> > So, no, reiserfs can tell stale filehandle, although not as reliable as
> > file systems with static inode tables.
> >
> > Hans-Peter, please tell me, what reiserfs format are you using. 3.5
> > doesn't support NFS reliably. If you are using 3.5 you'll have to
> > upgrade to 3.6 format (copy data to the new file system). mount -o conv
> > will not eliminate this problem completely, but will make it much less
> > probable, so you can try this first.
>
> Bad luck for me, obviously :-(
>
> <4>reiserfs: checking transaction log (device 03:09) ...
> <4>Using r5 hash to sort names
> <4>reiserfs: using 3.5.x disk format

[...]

> <4>reiserfs: using 3.5.x disk format
> <4>ReiserFS version 3.6.25
>
> We're talking about 100 GB on _this_ server.

3.6. is advantageous because of many other things, like LFS, etc.

>
> How big is the chance to loose data with -o conv?

There were problems with -o conv and remount (for root file system), but
they were cured in latest Marcelo's kernels.

>
> Is there any paper around, which describes this conversion
> a bit more detailed? If I understand you correctly, the inode
> generation counter doesn't work at all with 3.5?

After file system is mounted with -o conv, all new files will be created
in a new format. This file system will then no longer be mountable as
3.5 (and thus, inaccessible from 2.2 kernels).

New files will store generation counters. The possibility of a stale
handle lurking undetected is when old-format file was deleted, its
objectid was reused for new format file, and super-block generation
counter at that time happens to coincide with objectid of parent
directory of the old file. Not exactly likely thing to happen, but
still.

>
> > > Cheers,
> > > Trond
> >

Nikita.

>
> Cheers,
> Hans-Peter
>
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:23    [W:0.055 / U:22.972 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site