linux-kernel - Re: [PATCH 2/2] fat (exportfs): reconnect file handles to evicted inodes/dentries

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Date:	Mon, 09 Jul 2012 12:23:58 -0500
From:	"Steven J. Magnani" <steve@...idescorp.com>
To:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] fat (exportfs): reconnect file handles to evicted
 inodes/dentries

On Mon, 2012-07-09 at 12:09 -0500, Steven J. Magnani wrote: 
> On Mon, 2012-07-09 at 11:27 -0500, Steven J. Magnani wrote: 
> > On Tue, 2012-07-10 at 01:10 +0900, OGAWA Hirofumi wrote: 
> > > If the inode is not on cache anymore, is there the possibility that
> > > selects the wrong parent? IIRC, NFS Server can be rebooted at any time
> > > while the client using the same file handle.
> > 
> > True, but it's looking like we can just use the default handle
> > constructed by export_encode_fh(), namely (i_ino, i_generation,
> > parent->i_ino, parent->i_generation). None of those components should
> > change in a server reboot.
> 
> I think I misunderstood you when I wrote this. I assumed we were talking
> about a restart of nfsd, not the entire machine it was running on. If
> there is a danger of mismapping on a reboot isn't that present in the
> existing mainline code, i.e. fat_fh_to_dentry()? Ideally, the (i_ino,
> i_generation) signature would be different on a reboot, although with
> only 2-second granularity in i_generation I suppose that's less likely
> than we would prefer. Also I would think that many inodes simply
> wouldn't exist in the cache, in which case we would fail the operation
> with ESTALE.

On further investigation I don't think there is an issue here.
i_generation is set to the value returned by get_seconds(), which is
wall-clock time, not relative time since boot.

------------------------------------------------------------------------
Steven J. Magnani               "I claim this network for MARS!
www.digidescorp.com              Earthling, return my space modulator!"

#include <standard.disclaimer>


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