diff --git a/sys/ufs/ffs/ffs_alloc.c b/sys/ufs/ffs/ffs_alloc.c
index 9b58c962d03..08e90f19e20 100644
--- a/sys/ufs/ffs/ffs_alloc.c
+++ b/sys/ufs/ffs/ffs_alloc.c
@@ -260,7 +260,11 @@ retry:
 		ip->i_flag |= IN_CHANGE | IN_UPDATE;
 		allocbuf(bp, nsize);
 		bp->b_flags |= B_DONE;
-		bzero((char *)bp->b_data + osize, (u_int)nsize - osize);
+		if ((bp->b_flags & (B_MALLOC | B_VMIO)) != B_VMIO)
+			bzero((char *)bp->b_data + osize,
+			    (u_int)nsize - osize);
+		else
+			vfs_bio_clrbuf(bp);
 		*bpp = bp;
 		return (0);
 	}
@@ -325,7 +329,11 @@ retry:
 		ip->i_flag |= IN_CHANGE | IN_UPDATE;
 		allocbuf(bp, nsize);
 		bp->b_flags |= B_DONE;
-		bzero((char *)bp->b_data + osize, (u_int)nsize - osize);
+		if ((bp->b_flags & (B_MALLOC | B_VMIO)) != B_VMIO)
+			bzero((char *)bp->b_data + osize,
+			    (u_int)nsize - osize);
+		else
+			vfs_bio_clrbuf(bp);
 		*bpp = bp;
 		return (0);
 	}