[src/trunk]: src/sys/fs/ntfs Lock the ntnode and recheck the fnode after call...

[hannken <hannken%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/2421c51fd1e0
branches:  trunk
changeset: 756473:2421c51fd1e0
user:      hannken <hannken%NetBSD.org@localhost>
date:      Mon Jul 19 08:17:44 2010 +0000

description:
Lock the ntnode and recheck the fnode after calling getnewvnode().

Take v_interlock while the ntnode is locked.

diffstat:

 sys/fs/ntfs/ntfs_vfsops.c |  41 +++++++++++++++++++++++++++++++----------
 1 files changed, 31 insertions(+), 10 deletions(-)

diffs (85 lines):

diff -r 08dc7feefada -r 2421c51fd1e0 sys/fs/ntfs/ntfs_vfsops.c
--- a/sys/fs/ntfs/ntfs_vfsops.c Mon Jul 19 05:34:24 2010 +0000
+++ b/sys/fs/ntfs/ntfs_vfsops.c Mon Jul 19 08:17:44 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ntfs_vfsops.c,v 1.82 2010/07/01 13:00:55 hannken Exp $ */
+/*     $NetBSD: ntfs_vfsops.c,v 1.83 2010/07/19 08:17:44 hannken Exp $ */
 
 /*-
  * Copyright (c) 1998, 1999 Semen Ustimenko
@@ -29,7 +29,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ntfs_vfsops.c,v 1.82 2010/07/01 13:00:55 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ntfs_vfsops.c,v 1.83 2010/07/19 08:17:44 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -726,6 +726,7 @@
        ntmp = VFSTONTFS(mp);
        *vpp = NULL;
 
+loop:
        /* Get ntnode */
        error = ntfs_ntlookup(ntmp, ino, &ip);
        if (error) {
@@ -778,23 +779,41 @@
         * lock has to be acquired first.
         * ntfs_fget() bumped ntnode usecount, so ntnode won't be recycled
         * prematurely.
+        * Take v_interlock before releasing ntnode lock to avoid races.
         */
+       vp = FTOV(fp);
+       if (vp) {
+               mutex_enter(&vp->v_interlock);
+               ntfs_ntput(ip);
+               if (vget(vp, LK_INTERLOCK | lkflags) != 0)
+                       goto loop;
+               *vpp = vp;
+               return 0;
+       }
        ntfs_ntput(ip);
 
-       if (FTOV(fp)) {
-               /* vget() returns error if the vnode has been recycled */
-               if (vget(FTOV(fp), lkflags) == 0) {
-                       *vpp = FTOV(fp);
-                       return (0);
-               }
-       }
-
        error = getnewvnode(VT_NTFS, ntmp->ntm_mountp, ntfs_vnodeop_p, &vp);
+       ntfs_ntget(ip);
        if(error) {
                ntfs_frele(fp);
                ntfs_ntput(ip);
                return (error);
        }
+       error = ntfs_fget(ntmp, ip, attrtype, attrname, &fp);
+       if (error) {
+               printf("ntfs_vget: ntfs_fget failed\n");
+               ntfs_ntput(ip);
+               return (error);
+       }
+       if (FTOV(fp)) {
+               /*
+                * Another thread beat us, put back freshly allocated
+                * vnode and retry.
+                */
+               ntfs_ntput(ip);
+               ungetnewvnode(vp);
+               goto loop;
+       }
        dprintf(("ntfs_vget: vnode: %p for ntnode: %llu\n", vp,
            (unsigned long long)ino));
 
@@ -807,6 +826,8 @@
        if (ino == NTFS_ROOTINO)
                vp->v_vflag |= VV_ROOT;
 
+       ntfs_ntput(ip);
+
        if (lkflags & (LK_EXCLUSIVE | LK_SHARED)) {
                error = vn_lock(vp, lkflags);
                if (error) {