Date: Sat, 27 Mar 2010 09:49:23 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: Petr Lampa <lampa@fit.vutbr.cz> Cc: freebsd-current@freebsd.org Subject: Re: Possible error in nfs_nfsdserv.c? Message-ID: <Pine.GSO.4.63.1003270930460.12032@muncher.cs.uoguelph.ca> In-Reply-To: <20100326162406.GA43912@fit.vutbr.cz>
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On Fri, 26 Mar 2010, Petr Lampa wrote: > > I've got several "panic: nfsrelpath", see attached photo. I've found > one place where it could probably happen, please, can you look at this? > > First name buffer is initialized in nfsrvd_link() with: > NFSNAMEICNDSET(&named.ni_cnd, nd->nd_cred, CREATE, LOCKPARENT); > > Then: > nd->nd_repstat = nfsvno_namei(nd, &named, dp, 0, &tnes, > p, &dirp); > > and > nd->nd_repstat = nfsvno_link(&named, vp, nd->nd_cred, p, exp); > > is called. The nfsvno_link() calls nfsvno_relpathbuf() unconditionally, > this is the place where the panic happened. The only place where buffer can > be released in no error case is in the nfsvno_namei(). There is a call > > if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) > nfsvno_relpathbuf(ndp); > > there and no SAVENAME|SAVESTART is set in NFSNAMEICNDSET(). But if > buffer is alwyas released at this place, then link would be panicing also > always (and it isn't). So probably I'm missing something here. Other For ufs, ufs_lookup() sets SAVENAME for the CREATE case, which is why I don't see such a panic. I had thought that all file systems would do this for VOP_LOOKUP() for CREATE. It sounds like you've found a case where that isn't happening. Could you please tell us what file system type is being accessed when this panic occurs? I've cc'd freebsd-current, so that anyone conversant with the FreeBSD VFS can jump in here. Am I right to assume that VOP_LOOKUP() for CREATE will set SAVENAME when returning error == 0? > functions where nfsvno_namei() is called without SAVENAME|SAVESTART flags > also don't call nfsvno_relpathbuf(). Perhaps buffer should be initialized > with > > NFSNAMEICNDSET(&named.ni_cnd, nd->nd_cred, CREATE, LOCKPARENT | SAVENAME); > Yes, please try this. I think it will fix the problem, since my server code assumes that VOP_LOOKUP() will have set SAVENAME for the non-error case. (I don't think setting it is harmful and it will help isolate the problem further.) Please let us know how things go with SAVENAME set, as above. rickhome | help
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