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Date: Wed, 4 Dec 2013 10:41:04 -0500
From: Dr Fields James Bruce <bfields@fieldses.org>
To: Antti =?utf-8?B?VMO2bmt5csOk?= <daedalus@pingtimeout.net>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: Patch for mapping EILSEQ into NFSERR_INVAL
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On Wed, Dec 04, 2013 at 08:55:04AM +0200, Antti Tönkyrä wrote:
> On 2013-12-03 23:22, Dr Fields James Bruce wrote:
> >On Tue, Dec 03, 2013 at 03:48:06PM -0500, Dr Fields James Bruce wrote:
> >>OK, it makes sense that touching a file with a bad name would get an
> >>error, but you're seeing that cause later creates of files on the same
> >>filesystem fail.  I can't figure out why that would happen.
> >...
> >
> >So maybe there's some other problem here, but...
> >
> >>>>>Given that widely used ntfs-3g FUSE module also returns EILSEQ on the same case (I tested this) I would argue that a fix should be done for upstream especially since RFC5661 clearly defines that invalid UTF-8 sequence should map into NFSERR_INVAL, exact quote: "Where the client sends an invalid UTF-8 string, the server should return NFS4ERR_INVAL (see Table 5)".
> >>>>The NFS client will then happily map that straight into EINVAL for you...
> >This seems like a spec bug?
> >
> >NFS4ERR_INVAL only makes sense if you could really mandate UTF-8 on the
> >wire all the time.  But I don't know what other error would work.
> >
> >I guess a client could map INVAL to EILSEQ on open or lookup (is there
> >any other reason a correct client should ever see INVAL on those ops?).
> >Or do that only if fs_charset is supported and has
> >FSCHARSET_CAP4_ALLOWS_ONLY_UTF8 set.  Yuch.
> >
> >--b.
> Hello,
> 
> I don't really think it's an issue if we don't do any mapping here
> either, I/O error is perfectly acceptable to me but the whole share
> dying is of course not very desirable...
> 
> I have been conducting my tests with ntfs-3g for now and after
> applying my patch to map EILSEQ into INVAL I didn't witness the
> share dying anymore. I captured network traffic from both cases
> (urls below). The tests were conducted so that after mounting the
> NFS share a file was opened (with w-mode) after which pcap was
> started. After that the following commands were executed:
> 
> touch `echo -e $'\some_bad_sequence'` (I tested these with \377 and \375)
> <wait a bit>
> touch something
> 
> http://daedalus.pingtimeout.net/dbg/eilseq_ioerr.pcap
> http://daedalus.pingtimeout.net/dbg/eilseq_mapped.pcap
> 
> With mapping patch applied, the bad sequence touch returns invalid
> argument but doesn't kill the share as somewhat visible from the
> pcap.

The later creates show up as opens for "something", and the server's
resending with NFSERR_IO on the open.

So, thanks, that probably rules out any client-side bug.

Since you're testing a fuse filesystem--is there an easy way to get some
debugging info out of it?  E.g. is it running as an ntfs-3g daemon that
you can strace?

--b.