[src/trunk]: src/sys/ufs/ffs No longer abuse TAILQ internal data.

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

details:   https://anonhg.NetBSD.org/src/rev/5a56d5e9e847
branches:  trunk
changeset: 748176:5a56d5e9e847
user:      hannken <hannken%NetBSD.org@localhost>
date:      Thu Oct 15 10:05:48 2009 +0000

description:
No longer abuse TAILQ internal data.

diffstat:

 sys/ufs/ffs/ffs_snapshot.c |  55 ++++++++++++++++++++++++++++++---------------
 1 files changed, 36 insertions(+), 19 deletions(-)

diffs (133 lines):

diff -r 14b011a9cc39 -r 5a56d5e9e847 sys/ufs/ffs/ffs_snapshot.c
--- a/sys/ufs/ffs/ffs_snapshot.c        Thu Oct 15 06:19:35 2009 +0000
+++ b/sys/ufs/ffs/ffs_snapshot.c        Thu Oct 15 10:05:48 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ffs_snapshot.c,v 1.96 2009/10/13 12:38:14 hannken Exp $        */
+/*     $NetBSD: ffs_snapshot.c,v 1.97 2009/10/15 10:05:48 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 1.96 2009/10/13 12:38:14 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ffs_snapshot.c,v 1.97 2009/10/15 10:05:48 hannken Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_ffs.h"
@@ -76,6 +76,14 @@
 
 #include <uvm/uvm.h>
 
+struct snap_info {
+       kmutex_t si_lock;                       /* Lock this snapinfo */
+       kmutex_t si_snaplock;                   /* Snapshot vnode common lock */
+       TAILQ_HEAD(inodelst, inode) si_snapshots; /* List of active snapshots */
+       daddr_t *si_snapblklist;                /* Snapshot block hints list */
+       uint32_t si_gen;                        /* Incremented on change */
+};
+
 #if !defined(FFS_NO_SNAPSHOT)
 typedef int (*acctfunc_t)
     (struct vnode *, void *, int, int, struct fs *, daddr_t, int);
@@ -107,6 +115,7 @@
 static int syncsnap(struct vnode *);
 static int wrsnapblk(struct vnode *, void *, daddr_t);
 
+static inline bool is_active_snapshot(struct snap_info *, struct inode *);
 static inline daddr_t db_get(struct inode *, int);
 static inline void db_assign(struct inode *, int, daddr_t);
 static inline daddr_t ib_get(struct inode *, int);
@@ -114,14 +123,6 @@
 static inline daddr_t idb_get(struct inode *, void *, int);
 static inline void idb_assign(struct inode *, void *, int, daddr_t);
 
-struct snap_info {
-       kmutex_t si_lock;                       /* Lock this snapinfo */
-       kmutex_t si_snaplock;                   /* Snapshot vnode common lock */
-       TAILQ_HEAD(inodelst, inode) si_snapshots; /* List of active snapshots */
-       daddr_t *si_snapblklist;                /* Snapshot block hints list */
-       uint32_t si_gen;                        /* Incremented on change */
-};
-
 #ifdef DEBUG
 static int snapdebug = 0;
 #endif
@@ -277,7 +278,7 @@
        fs->fs_snapinum[snaploc] = ip->i_number;
 
        mutex_enter(&si->si_lock);
-       if (ip->i_nextsnap.tqe_prev != 0)
+       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);
        if (TAILQ_FIRST(&si->si_snapshots) == ip) {
@@ -1318,10 +1319,9 @@
         *
         * Clear copy-on-write flag if last snapshot.
         */
-       if (ip->i_nextsnap.tqe_prev != 0) {
-               mutex_enter(&si->si_lock);
+       mutex_enter(&si->si_lock);
+       if (is_active_snapshot(si, ip)) {
                TAILQ_REMOVE(&si->si_snapshots, ip, i_nextsnap);
-               ip->i_nextsnap.tqe_prev = 0;
                if (TAILQ_FIRST(&si->si_snapshots) != 0) {
                        /* Roll back the list of preallocated blocks. */
                        xp = TAILQ_LAST(&si->si_snapshots, inodelst);
@@ -1338,7 +1338,8 @@
                        free(ip->i_snapblklist, M_UFSMNT);
                        ip->i_snapblklist = NULL;
                }
-       }
+       } else
+               mutex_exit(&si->si_lock);
        /*
         * Clear all BLK_NOCOPY fields. Pass any block claims to other
         * snapshots that want them (see ffs_snapblkfree below).
@@ -1678,9 +1679,9 @@
                /*
                 * Link it onto the active snapshot list.
                 */
-               if (ip->i_nextsnap.tqe_prev != 0)
-                       panic("ffs_snapshot_mount: %llu already on list",
-                           (unsigned long long)ip->i_number);
+               if (is_active_snapshot(si, ip))
+                       panic("ffs_snapshot_mount: %"PRIu64" already on list",
+                           ip->i_number);
                else
                        TAILQ_INSERT_TAIL(&si->si_snapshots, ip, i_nextsnap);
                vp->v_vflag |= VV_SYSTEM;
@@ -1720,7 +1721,6 @@
        while ((xp = TAILQ_FIRST(&si->si_snapshots)) != 0) {
                vp = ITOV(xp);
                TAILQ_REMOVE(&si->si_snapshots, xp, i_nextsnap);
-               xp->i_nextsnap.tqe_prev = 0;
                if (xp->i_snapblklist == si->si_snapblklist)
                        si->si_snapblklist = NULL;
                free(xp->i_snapblklist, M_UFSMNT);
@@ -2121,6 +2121,23 @@
 }
 
 /*
+ * Check if this inode is present on the active snapshot list.
+ * Must be called with snapinfo locked.
+ */
+static inline bool
+is_active_snapshot(struct snap_info *si, struct inode *ip)
+{
+       struct inode *xp;
+
+       KASSERT(mutex_owned(&si->si_lock));
+
+       TAILQ_FOREACH(xp, &si->si_snapshots, i_nextsnap)
+               if (xp == ip)
+                       return true;
+       return false;
+}
+
+/*
  * Get/Put direct block from inode or buffer containing disk addresses. Take
  * care for fs type (UFS1/UFS2) and byte swapping. These functions should go
  * into a global include.