From owner-freebsd-hackers  Fri Oct 20  9:18:16 2000
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Date: Fri, 20 Oct 2000 17:18:10 +0100
From: David Malone <dwmalone@maths.tcd.ie>
To: Vadim Belman <voland@lflat.org>
Cc: freebsd-hackers@freebsd.org
Subject: Re: NFS/VM deadlock report and help request
Message-ID: <20001020171810.A28345@walton.maths.tcd.ie>
References: <20001020145043.B73760@lflat.vas.mobilix.dk>
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In-Reply-To: <20001020145043.B73760@lflat.vas.mobilix.dk>; from voland@lflat.org on Fri, Oct 20, 2000 at 02:50:43PM +0200
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On Fri, Oct 20, 2000 at 02:50:43PM +0200, Vadim Belman wrote:

> 	The kernel config I supply as an attachment. Kernel-mode stack
> trace for the thttpd process looks like this:

I think we've seen a similar problem and have a work around for it.
You could try the following patch, though it might take more fiddling
to get it right.

(The patch is by Ian Dowse, Matt Dillon had a quick look at it and said
it looked OK, we've been testing it for a bit here).

	David.

Index: nfs/nfs.h
===================================================================
RCS file: /FreeBSD/FreeBSD-CVS/src/sys/nfs/nfs.h,v
retrieving revision 1.53
diff -u -r1.53 nfs.h
--- nfs/nfs.h	2000/01/13 20:18:25	1.53
+++ nfs/nfs.h	2000/10/20 16:13:49
@@ -616,7 +616,7 @@
 			 struct ucred *, struct mbuf **, struct mbuf **,
 			 caddr_t *));
 int	nfs_loadattrcache __P((struct vnode **, struct mbuf **, caddr_t *,
-			       struct vattr *));
+			       struct vattr *, int));
 int	nfs_namei __P((struct nameidata *, fhandle_t *, int,
 		       struct nfssvc_sock *, struct sockaddr *, struct mbuf **,
 		       caddr_t *, struct vnode **, struct proc *, int, int));
Index: nfs/nfs_subs.c
===================================================================
RCS file: /FreeBSD/FreeBSD-CVS/src/sys/nfs/nfs_subs.c,v
retrieving revision 1.90
diff -u -r1.90 nfs_subs.c
--- nfs/nfs_subs.c	2000/02/13 03:32:06	1.90
+++ nfs/nfs_subs.c	2000/10/20 16:13:49
@@ -1203,11 +1203,12 @@
  *    copy the attributes to *vaper
  */
 int
-nfs_loadattrcache(vpp, mdp, dposp, vaper)
+nfs_loadattrcache(vpp, mdp, dposp, vaper, dontshrink)
 	struct vnode **vpp;
 	struct mbuf **mdp;
 	caddr_t *dposp;
 	struct vattr *vaper;
+	int dontshrink;
 {
 	register struct vnode *vp = *vpp;
 	register struct vattr *vap;
@@ -1322,9 +1323,18 @@
 		vap->va_gen = fxdr_unsigned(u_int32_t,fp->fa2_ctime.nfsv2_usec);
 		vap->va_filerev = 0;
 	}
+	np->n_attrstamp = time_second;
 	if (vap->va_size != np->n_size) {
 		if (vap->va_type == VREG) {
-			if (np->n_flag & NMODIFIED) {
+			if (dontshrink && vap->va_size < np->n_size) {
+				/*
+				 * We've been told not to shrink the file;
+				 * zero np->n_attrstamp to indicate that
+				 * the attributes are stale.
+				 */
+				vap->va_size = np->n_size;
+				np->n_attrstamp = 0;
+			} else if (np->n_flag & NMODIFIED) {
 				if (vap->va_size < np->n_size)
 					vap->va_size = np->n_size;
 				else
@@ -1337,7 +1347,6 @@
 			np->n_size = vap->va_size;
 		}
 	}
-	np->n_attrstamp = time_second;
 	if (vaper != NULL) {
 		bcopy((caddr_t)vap, (caddr_t)vaper, sizeof(*vap));
 		if (np->n_flag & NCHG) {
Index: nfs/nfsm_subs.h
===================================================================
RCS file: /FreeBSD/FreeBSD-CVS/src/sys/nfs/nfsm_subs.h,v
retrieving revision 1.27
diff -u -r1.27 nfsm_subs.h
--- nfs/nfsm_subs.h	1999/08/28 00:50:02	1.27
+++ nfs/nfsm_subs.h	2000/10/20 16:13:49
@@ -212,7 +212,7 @@
 #define	nfsm_loadattr(v, a) \
 	do { \
 		struct vnode *ttvp = (v); \
-		if ((t1 = nfs_loadattrcache(&ttvp, &md, &dpos, (a))) != 0) { \
+		if ((t1 = nfs_loadattrcache(&ttvp, &md, &dpos, (a), 0)) != 0) { \
 			error = t1; \
 			m_freem(mrep); \
 			goto nfsmout; \
@@ -226,7 +226,7 @@
 		nfsm_dissect(tl, u_int32_t *, NFSX_UNSIGNED); \
 		if (((f) = fxdr_unsigned(int, *tl)) != 0) { \
 			if ((t1 = nfs_loadattrcache(&ttvp, &md, &dpos, \
-				(struct vattr *)0)) != 0) { \
+				(struct vattr *)0, 1)) != 0) { \
 				error = t1; \
 				(f) = 0; \
 				m_freem(mrep); \


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