Date: Mon, 23 Jan 2012 10:56:54 -0500 (EST) From: Rick Macklem <rmacklem@uoguelph.ca> To: Jaakko Heinonen <jh@FreeBSD.org> Cc: freebsd-fs@freebsd.org Subject: Re: should mount -u fail or silently ignore options? Message-ID: <219911446.737753.1327334214785.JavaMail.root@erie.cs.uoguelph.ca> In-Reply-To: <20120123153833.GB2246@a91-153-116-96.elisa-laajakaista.fi>
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Jaakko Heinonen wrote: > On 2012-01-22, Rick Macklem wrote: > > There is a bug in the NFS clients, where a > > "mount -u -o udp /mnt" will cause any threads > > that have an RPC in progress to hang, if the > > mount previously was using too large an rsize/wsize. > > Does the hang occur if the UDP transport was already used? > I don't think so. I did test the case where it switched from TCP to UDP, but the TCP mount had rsize=16384,wsize=16384 and that was fine. The problem occurs when the rsize/wsize for the mount is > 16K before the change to UDP (which "can't" be the case if the mount is already UDP). The patch only generates an error if the old rsize/wsize is greater than 16K. Or, it could be easily re-written to silently ignore the request to switch to UDP. > > This case can easily be detected in nfs_mount(). > > > > However, my question is... > > - Should the "mount -u" fail and return an error > > OR > > Silently ignore the "udp" option and return ok. > > Depending on the answer to the question above, IMHO the best solution > would be to return an error if user tries to change TCP to UDP but > accept the "udp" option if UDP transport is already active. I don't > know > about potential problems with root nfs. > Yea, I feel returning an error makes more sense than silently ignoring the request. The concerns I had were related to diskless roots. Thanks for the comments, rick > -- > Jaakko
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