- Use vrefcnt() where it is safe to do so instead of doing direct and

   unlocked accesses to v_usecount.
 - Lock access to the buf lists in the various sync routines.  interlock
   locking could be avoided almost entirely in leaf filesystems if the
   fsync function had a generic helper.

3 files changed, 15 insertions, 11 deletions

diff --git a/sys/fs/msdosfs/msdosfs_denode.c b/sys/fs/msdosfs/msdosfs_denode.c
index 9b12552..6a141bec 100644
--- a/sys/fs/msdosfs/msdosfs_denode.c
+++ b/sys/fs/msdosfs/msdosfs_denode.c
@@ -653,7 +653,7 @@ msdosfs_reclaim(ap)
 	    dep, dep->de_Name, dep->de_refcnt);
 #endif
 
-	if (prtactive && vp->v_usecount != 0)
+	if (prtactive && vrefcnt(vp) != 0)
 		vprint("msdosfs_reclaim(): pushing active", vp);
 	/*
 	 * Remove the denode from its hash chain.
@@ -693,7 +693,7 @@ msdosfs_inactive(ap)
 	printf("msdosfs_inactive(): dep %p, de_Name[0] %x\n", dep, dep->de_Name[0]);
 #endif
 
-	if (prtactive && vp->v_usecount != 0)
+	if (prtactive && vrefcnt(vp) != 0)
 		vprint("msdosfs_inactive(): pushing active", vp);
 
 	/*
@@ -725,8 +725,8 @@ out:
 	 * so that it can be reused immediately.
 	 */
 #ifdef MSDOSFS_DEBUG
-	printf("msdosfs_inactive(): v_usecount %d, de_Name[0] %x\n", vp->v_usecount,
-	       dep->de_Name[0]);
+	printf("msdosfs_inactive(): v_usecount %d, de_Name[0] %x\n",
+	       vrefcnt(vp), dep->de_Name[0]);
 #endif
 	if (dep->de_Name[0] == SLOT_DELETED)
 		vrecycle(vp, NULL, td);
diff --git a/sys/fs/msdosfs/msdosfs_vfsops.c b/sys/fs/msdosfs/msdosfs_vfsops.c
index bd3703d..f7994b6 100644
--- a/sys/fs/msdosfs/msdosfs_vfsops.c
+++ b/sys/fs/msdosfs/msdosfs_vfsops.c
@@ -635,6 +635,7 @@ msdosfs_unmount(mp, mntflags, td)
 	{
 		struct vnode *vp = pmp->pm_devvp;
 
+		VI_LOCK(vp);
 		printf("msdosfs_umount(): just before calling VOP_CLOSE()\n");
 		printf("iflag %08lx, usecount %d, writecount %d, holdcnt %ld\n",
 		    vp->vi_flag, vp->v_usecount, vp->v_writecount,
@@ -652,6 +653,7 @@ msdosfs_unmount(mp, mntflags, td)
 		    vp->v_socket, vp->v_tag,
 		    ((u_int *)vp->v_data)[0],
 		    ((u_int *)vp->v_data)[1]);
+		VI_UNLOCK(vp);
 	}
 #endif
 	error = VOP_CLOSE(pmp->pm_devvp,
@@ -747,13 +749,13 @@ loop:
 		nvp = TAILQ_NEXT(vp, v_nmntvnodes);
 
 		mtx_unlock(&mntvnode_mtx);
-		mtx_lock(&vp->v_interlock);
+		VI_LOCK(vp);
 		dep = VTODE(vp);
 		if (vp->v_type == VNON ||
 		    ((dep->de_flag &
 		    (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0 &&
 		    (TAILQ_EMPTY(&vp->v_dirtyblkhd) || waitfor == MNT_LAZY))) {
-			mtx_unlock(&vp->v_interlock);
+			VI_UNLOCK(vp);
 			mtx_lock(&mntvnode_mtx);
 			continue;
 		}
diff --git a/sys/fs/msdosfs/msdosfs_vnops.c b/sys/fs/msdosfs/msdosfs_vnops.c
index b7d4f7c..b7ef69f 100644
--- a/sys/fs/msdosfs/msdosfs_vnops.c
+++ b/sys/fs/msdosfs/msdosfs_vnops.c
@@ -218,12 +218,12 @@ msdosfs_close(ap)
 	struct denode *dep = VTODE(vp);
 	struct timespec ts;
 
-	mtx_lock(&vp->v_interlock);
+	VI_LOCK(vp);
 	if (vp->v_usecount > 1) {
 		getnanotime(&ts);
 		DETIMES(dep, &ts, &ts, &ts);
 	}
-	mtx_unlock(&vp->v_interlock);
+	VI_UNLOCK(vp);
 	return 0;
 }
 
@@ -818,13 +818,15 @@ loop:
 	VI_LOCK(vp);
 	for (bp = TAILQ_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
 		nbp = TAILQ_NEXT(bp, b_vnbufs);
-		if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT))
+		VI_UNLOCK(vp);
+		if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
+			VI_LOCK(vp);
 			continue;
+		}
 		if ((bp->b_flags & B_DELWRI) == 0)
 			panic("msdosfs_fsync: not dirty");
 		bremfree(bp);
 		splx(s);
-		VI_UNLOCK(vp);
 		/* XXX Could do bawrite */
 		(void) bwrite(bp);
 		goto loop;
@@ -834,13 +836,13 @@ loop:
 		(void) msleep((caddr_t)&vp->v_numoutput, VI_MTX(vp),
 		    PRIBIO + 1, "msdosfsn", 0);
 	}
-	VI_UNLOCK(vp);
 #ifdef DIAGNOSTIC
 	if (!TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
 		vprint("msdosfs_fsync: dirty", vp);
 		goto loop;
 	}
 #endif
+	VI_UNLOCK(vp);
 	splx(s);
 	return (deupdat(VTODE(vp), ap->a_waitfor == MNT_WAIT));
 }