Re: Possible NFS bug in 2.6.34...

[Trond Myklebust]

On Sat, 2010-05-22 at 09:18 -0700, Stuart Sheldon wrote: 
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> On 05/22/2010 09:09 AM, Trond Myklebust wrote:
> > Do you see any more NFS traffic to the server when the above hang
> > occurs? I'm wondering if we don't need something like the following
> > patch.
> > 
> > Cheers
> >   Trond 
> > --------------------------------------------------------------------------------
> > From 0b574497e05f62fd49cfe26f1b97e3669525446c Mon Sep 17 00:00:00 2001
> > From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
> > Date: Sat, 22 May 2010 11:49:19 -0400
> > Subject: [PATCH] NFS: Ensure that we mark the inode as dirty if we exit early from commit
> > 
> > If we exit from nfs_commit_inode() without ensuring that the COMMIT rpc
> > call has been completed, we must re-mark the inode as dirty. Otherwise,
> > future calls to sync_inode() with the WB_SYNC_ALL flag set will fail to
> > ensure that the data is on the disk.
> > 
> > Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
> > Cc: stable@xxxxxxxxxx
> > ---
> >  fs/nfs/write.c |   13 +++++++++++--
> >  1 files changed, 11 insertions(+), 2 deletions(-)
> > 
> > diff --git a/fs/nfs/write.c b/fs/nfs/write.c
> > index 3aea3ca..b8a6d7a 100644
> > --- a/fs/nfs/write.c
> > +++ b/fs/nfs/write.c
> > @@ -1386,7 +1386,7 @@ static int nfs_commit_inode(struct inode *inode, int how)
> >  	int res = 0;
> >  
> >  	if (!nfs_commit_set_lock(NFS_I(inode), may_wait))
> > -		goto out;
> > +		goto out_mark_dirty;
> >  	spin_lock(&inode->i_lock);
> >  	res = nfs_scan_commit(inode, &head, 0, 0);
> >  	spin_unlock(&inode->i_lock);
> > @@ -1398,9 +1398,18 @@ static int nfs_commit_inode(struct inode *inode, int how)
> >  			wait_on_bit(&NFS_I(inode)->flags, NFS_INO_COMMIT,
> >  					nfs_wait_bit_killable,
> >  					TASK_KILLABLE);
> > +		else
> > +			goto out_mark_dirty;
> >  	} else
> >  		nfs_commit_clear_lock(NFS_I(inode));
> > -out:
> > +	return res;
> > +	/* Note: If we exit without ensuring that the commit is complete,
> > +	 * we must mark the inode as dirty. Otherwise, future calls to
> > +	 * sync_inode() with the WB_SYNC_ALL flag set will fail to ensure
> > +	 * that the data is on the disk.
> > +	 */
> > +out_mark_dirty:
> > +	__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
> >  	return res;
> >  }
> >  
> 
> Trond,
> 
> When it occurred, it continues to throw those errors in the log, and all
> access to the NFS mount stalled until I hard reset the client system.
> 
> Do you want me to apply the patch and see if I can recreate the condition?

Yes, please do. Could you also apply the following debugging patch on
top of the above one, and see if the WARN_ON() triggers when both
patches are applied?

Cheers
  Trond 
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