[src/trunk]: src/sys/ufs/ffs Keep a reference to the snapshot vnode until it ...

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

details:   https://anonhg.NetBSD.org/src/rev/d9333e76a737
branches:  trunk
changeset: 759525:d9333e76a737
user:      hannken <hannken%NetBSD.org@localhost>
date:      Sun Dec 12 10:29:25 2010 +0000

description:
Keep a reference to the snapshot vnode until it gets removed from the
snapshot list.

diffstat:

 sys/ufs/ffs/ffs_snapshot.c |  40 ++++++++++++++++++----------------------
 1 files changed, 18 insertions(+), 22 deletions(-)

diffs (97 lines):

diff -r 2ff735e28d9d -r d9333e76a737 sys/ufs/ffs/ffs_snapshot.c
--- a/sys/ufs/ffs/ffs_snapshot.c        Sun Dec 12 10:28:22 2010 +0000
+++ b/sys/ufs/ffs/ffs_snapshot.c        Sun Dec 12 10:29:25 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ffs_snapshot.c,v 1.100 2010/12/12 10:28:22 hannken Exp $       */
+/*     $NetBSD: ffs_snapshot.c,v 1.101 2010/12/12 10:29:25 hannken Exp $       */
 
 /*
  * Copyright 2000 Marshall Kirk McKusick. All Rights Reserved.
@@ -38,7 +38,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ffs_snapshot.c,v 1.100 2010/12/12 10:28:22 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ffs_snapshot.c,v 1.101 2010/12/12 10:29:25 hannken Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_ffs.h"
@@ -278,6 +278,7 @@
        fs->fs_snapinum[snaploc] = ip->i_number;
 
        mutex_enter(&si->si_lock);
+       vref(vp);
        if (is_active_snapshot(si, ip))
                panic("ffs_snapshot: %"PRIu64" already on list", ip->i_number);
        TAILQ_INSERT_TAIL(&si->si_snapshots, ip, i_nextsnap);
@@ -391,8 +392,7 @@
                        (void) ffs_truncate(vp, (off_t)0, 0, NOCRED);
                        UFS_WAPBL_END(mp);
                }
-       } else
-               vref(vp);
+       }
        return (error);
 }
 
@@ -1269,10 +1269,8 @@
                if (xp == ip)
                        break;
        mutex_exit(&si->si_lock);
-       if (xp != NULL)
-               vrele(ITOV(ip));
 #ifdef DEBUG
-       else if (snapdebug)
+       if (snapdebug && xp == NULL)
                printf("ffs_snapgone: lost snapshot vnode %llu\n",
                    (unsigned long long)ip->i_number);
 #endif
@@ -1339,6 +1337,7 @@
                        free(ip->i_snapblklist, M_UFSMNT);
                        ip->i_snapblklist = NULL;
                }
+               vrele(vp);
        } else
                mutex_exit(&si->si_lock);
        /*
@@ -1713,28 +1712,25 @@
 ffs_snapshot_unmount(struct mount *mp)
 {
        struct vnode *devvp = VFSTOUFS(mp)->um_devvp;
-       struct inode *xp;
-       struct vnode *vp = NULL;
+       struct inode *ip;
        struct snap_info *si;
+       bool list_empty = true;
 
        si = VFSTOUFS(mp)->um_snapinfo;
        mutex_enter(&si->si_lock);
-       while ((xp = TAILQ_FIRST(&si->si_snapshots)) != 0) {
-               vp = ITOV(xp);
-               TAILQ_REMOVE(&si->si_snapshots, xp, i_nextsnap);
-               if (xp->i_snapblklist == si->si_snapblklist)
+       while ((ip = TAILQ_FIRST(&si->si_snapshots)) != 0) {
+               list_empty = false;
+               TAILQ_REMOVE(&si->si_snapshots, ip, i_nextsnap);
+               if (ip->i_snapblklist == si->si_snapblklist)
                        si->si_snapblklist = NULL;
-               free(xp->i_snapblklist, M_UFSMNT);
-               if (xp->i_nlink > 0) {
-                       si->si_gen++;
-                       mutex_exit(&si->si_lock);
-                       vrele(vp);
-                       mutex_enter(&si->si_lock);
-               }
+               free(ip->i_snapblklist, M_UFSMNT);
+               si->si_gen++;
+               mutex_exit(&si->si_lock);
+               vrele(ITOV(ip));
+               mutex_enter(&si->si_lock);
        }
-       si->si_gen++;
        mutex_exit(&si->si_lock);
-       if (vp)
+       if (! list_empty)
                fscow_disestablish(mp, ffs_copyonwrite, devvp);
 }