Index: kern/vfs_bio.c
===================================================================
--- kern/vfs_bio.c	(revision 226982)
+++ kern/vfs_bio.c	(working copy)
@@ -2781,7 +2781,7 @@
 			return NULL;
 		bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
 		offset = blkno * bsize;
-		vmio = vp->v_object != NULL;
+		vmio = vp->v_object != NULL && (flags & GB_NOVMIO) == 0;
 		maxsize = vmio ? size + (offset & PAGE_MASK) : size;
 		maxsize = imax(maxsize, bsize);
 
Index: sys/buf.h
===================================================================
--- sys/buf.h	(revision 226982)
+++ sys/buf.h	(working copy)
@@ -451,6 +451,7 @@
 #define	GB_LOCK_NOWAIT	0x0001		/* Fail if we block on a buf lock. */
 #define	GB_NOCREAT	0x0002		/* Don't create a buf if not found. */
 #define	GB_NOWAIT_BD	0x0004		/* Do not wait for bufdaemon */
+#define	GB_NOVMIO	0x0008		/* Don't use VMIO. */
 
 #ifdef _KERNEL
 extern int	nbuf;			/* The number of buffer headers */
Index: ufs/ufs/ufs_bmap.c
===================================================================
--- ufs/ufs/ufs_bmap.c	(revision 226982)
+++ ufs/ufs/ufs_bmap.c	(working copy)
@@ -213,7 +213,8 @@
 			bqrelse(bp);
 
 		ap->in_exists = 1;
-		bp = getblk(vp, metalbn, mp->mnt_stat.f_iosize, 0, 0, 0);
+		bp = getblk(vp, metalbn, mp->mnt_stat.f_iosize, 0, 0,
+		    GB_NOVMIO);
 		if ((bp->b_flags & B_CACHE) == 0) {
 #ifdef INVARIANTS
 			if (!daddr)
Index: ufs/ffs/ffs_softdep.c
===================================================================
--- ufs/ffs/ffs_softdep.c	(revision 226982)
+++ ufs/ffs/ffs_softdep.c	(working copy)
@@ -5819,7 +5819,7 @@
 	if (blkno == 0)
 		return (0);
 	mp = freeblks->fb_list.wk_mp;
-	bp = getblk(ITOV(ip), lbn, mp->mnt_stat.f_iosize, 0, 0, 0);
+	bp = getblk(ITOV(ip), lbn, mp->mnt_stat.f_iosize, 0, 0, GB_NOVMIO);
 	if ((bp->b_flags & B_CACHE) == 0) {
 		bp->b_blkno = blkptrtodb(VFSTOUFS(mp), blkno);
 		bp->b_iocmd = BIO_READ;
Index: ufs/ffs/ffs_balloc.c
===================================================================
--- ufs/ffs/ffs_balloc.c	(revision 226982)
+++ ufs/ffs/ffs_balloc.c	(working copy)
@@ -254,7 +254,8 @@
 		nb = newb;
 		*allocblk++ = nb;
 		*lbns_remfree++ = indirs[1].in_lbn;
-		bp = getblk(vp, indirs[1].in_lbn, fs->fs_bsize, 0, 0, 0);
+		bp = getblk(vp, indirs[1].in_lbn, fs->fs_bsize, 0, 0,
+		    GB_NOVMIO);
 		bp->b_blkno = fsbtodb(fs, nb);
 		vfs_bio_clrbuf(bp);
 		if (DOINGSOFTDEP(vp)) {
@@ -318,7 +319,8 @@
 		nb = newb;
 		*allocblk++ = nb;
 		*lbns_remfree++ = indirs[i].in_lbn;
-		nbp = getblk(vp, indirs[i].in_lbn, fs->fs_bsize, 0, 0, 0);
+		nbp = getblk(vp, indirs[i].in_lbn, fs->fs_bsize, 0, 0,
+		    GB_NOVMIO);
 		nbp->b_blkno = fsbtodb(fs, nb);
 		vfs_bio_clrbuf(nbp);
 		if (DOINGSOFTDEP(vp)) {
@@ -792,7 +794,8 @@
 		nb = newb;
 		*allocblk++ = nb;
 		*lbns_remfree++ = indirs[1].in_lbn;
-		bp = getblk(vp, indirs[1].in_lbn, fs->fs_bsize, 0, 0, 0);
+		bp = getblk(vp, indirs[1].in_lbn, fs->fs_bsize, 0, 0,
+		    GB_NOVMIO);
 		bp->b_blkno = fsbtodb(fs, nb);
 		vfs_bio_clrbuf(bp);
 		if (DOINGSOFTDEP(vp)) {
@@ -856,7 +859,8 @@
 		nb = newb;
 		*allocblk++ = nb;
 		*lbns_remfree++ = indirs[i].in_lbn;
-		nbp = getblk(vp, indirs[i].in_lbn, fs->fs_bsize, 0, 0, 0);
+		nbp = getblk(vp, indirs[i].in_lbn, fs->fs_bsize, 0, 0,
+		    GB_NOVMIO);
 		nbp->b_blkno = fsbtodb(fs, nb);
 		vfs_bio_clrbuf(nbp);
 		if (DOINGSOFTDEP(vp)) {