Date: Thu, 15 Nov 2007 15:12:00 +0200 From: Timo Sirainen <tss@iki.fi> To: Robert Watson <rwatson@FreeBSD.org> Cc: Adam McDougall <mcdouga9@egr.msu.edu>, freebsd-current@FreeBSD.org Subject: Re: link() not increasing link count on NFS server Message-ID: <1195132320.6039.135.camel@hurina> In-Reply-To: <20071115123543.H82897@fledge.watson.org> References: <20071115074247.GQ37473@egr.msu.edu> <20071115123543.H82897@fledge.watson.org>
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[-- Attachment #1 --] On Thu, 2007-11-15 at 12:39 +0000, Robert Watson wrote: > > or Solaris NFS clients. Basically, Timo (cc'ed) came up with a small test > > case that seems to indicate sometimes a link() call can succeed while the > > link count of the file will not increase. If this is ran on two FreeBSD > > clients from the same NFS directory, you will occasionally see "link() > > succeeded, but link count=1". I've tried both a Netapp and a FreeBSD NFS .. > My guess, and this is just a hand-wave, is that the attribute cache in the NFS > client isn't being forced to refresh, and hence you're getting the old stat > data back (and perhaps there's no GETATTR on the wire, which might hint at > this). If you'd like, you can post a link to the pcap capture file and one of > us can take a look, but I've found NFS RPCs to be surprisingly readable in > Wireshark so you might find it sheds quite a bit of light. Actually the point was that link() returns success even though in reality it fails. The fstat() was just a workaround to catch this case and treat link count 1 as if link() had failed with EEXIST. After that I had no more problems with locking. I noticed this first because my dotlocking was failing to lock files properly. I also added fchown() to flush attribute cache after link() and before fstat(), it gives the same link count=1 reply. [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBHPEWgyUhSUUBViskRAgdUAJ9oxcaapCx9OHuzztVA0DCjGA4VkwCgjZ3j cILNJPWfmbnGnqjX9NPnaxM= =6qV6 -----END PGP SIGNATURE-----
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