Date: Mon, 18 Dec 2006 16:20:21 GMT From: Ulrich Spoerlein <uspoerlein@gmail.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/92785: Using exported filesystem on OS/2 NFS client causes filesystem freeze Message-ID: <200612181620.kBIGKLBn030373@freefall.freebsd.org>
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The following reply was made to PR kern/92785; it has been noted by GNATS.
From: Ulrich Spoerlein <uspoerlein@gmail.com>
To: Konstantin Belousov <kostikbel@gmail.com>
Cc: bug-followup@freebsd.org
Subject: Re: kern/92785: Using exported filesystem on OS/2 NFS client causes filesystem freeze
Date: Mon, 18 Dec 2006 16:08:34 +0100
Konstantin Belousov wrote:
> Try this (not ever booted kernel with this patch applied, beware).
>
> Index: ufs/ufs/ufs_lookup.c
> ===================================================================
> RCS file: /usr/local/arch/ncvs/src/sys/ufs/ufs/ufs_lookup.c,v
> retrieving revision 1.82
> diff -u -r1.82 ufs_lookup.c
> --- ufs/ufs/ufs_lookup.c 31 Jul 2006 15:44:13 -0000 1.82
> +++ ufs/ufs/ufs_lookup.c 15 Dec 2006 15:42:43 -0000
> @@ -556,7 +553,10 @@
> * that point backwards in the directory structure.
> */
> pdp = vdp;
> - if (flags & ISDOTDOT) {
> + if (dp->i_number == dp->i_ino) {
> + VREF(vdp); /* we want ourself, ie "." */
> + *vpp = vdp;
> + } else if (flags & ISDOTDOT) {
> saved_ino = dp->i_ino;
> VOP_UNLOCK(pdp, 0, td); /* race to get the inode */
> error = VFS_VGET(pdp->v_mount, saved_ino,
> @@ -565,9 +565,6 @@
> if (error)
> return (error);
> *vpp = tdp;
> - } else if (dp->i_number == dp->i_ino) {
> - VREF(vdp); /* we want ourself, ie "." */
> - *vpp = vdp;
> } else {
> error = VFS_VGET(pdp->v_mount, dp->i_ino,
> cnp->cn_lkflags, &tdp);
I had a colleague of mine test this while instructing him over the phone
and it seems to fix the problem. No deadlocks, no leaks, the OS/2
clients can mount/ls/umount at will. All seems well.
Extensive tests have NOT yet been done. I'm also a little uneasy, as the
patch changes code that has been there since revision 1.1. I wonder how
4.x managed these OS/2 clients. Perhaps the old nfsd/rpc code rejected
these bogus lookups?
Anyway, thank you very much for the patch, we will be running it on our
server base shortly.
Ulrich Spoerlein
PS: Since this fix is UFS specific, what's with the other filesystems
that can be NFS exported? I think I'll do some test with ext2fs or
msdosfs exported filesystems next week.
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