svn commit: r355210 - head/sys/fs/nfsclient

[Konstantin Belousov]

Author: kib
Date: Fri Nov 29 13:55:56 2019
New Revision: 355210
URL: https://svnweb.freebsd.org/changeset/base/355210

Log:
  In nfs_lock(), recheck vp->v_data after lock before accessing it.
  
  We might race with reclaim, and then this is no longer a nfs vnode, in
  which case we do not need to handle deferred vnode_pager_setsize()
  either.
  
  Reported by:	rk at ronald.org
  PR:	 242184
  Sponsored by:	The FreeBSD Foundation
  MFC after:	3 days

Modified:
  head/sys/fs/nfsclient/nfs_clvnops.c

Modified: head/sys/fs/nfsclient/nfs_clvnops.c
==============================================================================
--- head/sys/fs/nfsclient/nfs_clvnops.c	Fri Nov 29 11:34:11 2019	(r355209)
+++ head/sys/fs/nfsclient/nfs_clvnops.c	Fri Nov 29 13:55:56 2019	(r355210)
@@ -312,6 +312,8 @@ nfs_lock(struct vop_lock1_args *ap)
 	if (error != 0 || vp->v_op != &newnfs_vnodeops)
 		return (error);
 	np = VTONFS(vp);
+	if (np == NULL)
+		return (0);
 	NFSLOCKNODE(np);
 	if ((np->n_flag & NVNSETSZSKIP) == 0 || (lktype != LK_SHARED &&
 	    lktype != LK_EXCLUSIVE && lktype != LK_UPGRADE &&
@@ -345,6 +347,9 @@ nfs_lock(struct vop_lock1_args *ap)
 		error = VOP_LOCK1_APV(&default_vnodeops, ap);
 		if (error != 0 || vp->v_op != &newnfs_vnodeops)
 			return (error);
+		if (vp->v_data == NULL)
+			goto downgrade;
+		MPASS(vp->v_data == np);
 		NFSLOCKNODE(np);
 		if ((np->n_flag & NVNSETSZSKIP) == 0) {
 			NFSUNLOCKNODE(np);