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To: NIIBE Yutaka <gniibe@m17n.org>
Cc: Stephan von Krawczynski <skraw@ithnet.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: BUG REPORT: kernel nfs between 2.4.19-pre2 (server) and 2.2.21-pre3 (client)
In-Reply-To: <shswuwkujx5.fsf@charged.uio.no>
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From: Trond Myklebust <trond.myklebust@fys.uio.no>
Date: 18 Mar 2002 09:15:06 +0100
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>>>>> " " == NIIBE Yutaka <gniibe@m17n.org> writes:

     > A problem is easily reproducible with user-space nfsd (on ext3,
     > in my case).  We see the message (say, when installing a
     > package with dpkg -i):
     > 	nfs_refresh_inode: inode XXXXXXX mode changed, OOOO to OOOO
     > Which means, same file handle but different type.

     > FWIW, I'm using the patch attached.  It works for me.

     > --- linux-2.4.18/fs/nfs/inode.c~ Wed Mar 13 17:56:48 2002
     > +++ linux-2.4.18.superh/fs/nfs/inode.c Mon Mar 18 13:27:39 2002
     > @@ -680,8 +680,10 @@ nfs_find_actor(struct inode *inode, unsi
     >  	if (is_bad_inode(inode))
     >  		return 0;
     >  	/* Force an attribute cache update if inode->i_count
     >  	== 0 */
     > - if (!atomic_read(&inode->i_count))
     > + if (!atomic_read(&inode->i_count)) {
     >  		NFS_CACHEINV(inode);
     > + inode->i_mode = 0;
     > +	}
     >  	return 1;
     >  }
 
Er... Why?

If you really want to change something in nfs_find_actor() then the
following works better w.r.t. init_special_inode() on character
devices:

        if ((inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
                return 0;

That doesn't fix all the races w.r.t. unfsd though: if someone on the
server removes a file that you have open for writing and replaces it
with a new one, you can still corrupt the new file.

Cheers,
  Trond