diff --git a/sys/ufs/ffs/ffs_subr.c b/sys/ufs/ffs/ffs_subr.c
--- a/sys/ufs/ffs/ffs_subr.c
+++ b/sys/ufs/ffs/ffs_subr.c
@@ -384,16 +384,35 @@
 ffs_oldfscompat_write(struct fs *fs)
 {
 
-	/*
-	 * Copy back UFS2 updated fields that UFS1 inspects.
-	 */
-	if (fs->fs_magic == FS_UFS1_MAGIC) {
+	switch (fs->fs_magic) {
+	case FS_UFS1_MAGIC:
+		if (fs->fs_sblockloc != SBLOCK_UFS1 &&
+		    (fs->fs_old_flags & FS_FLAGS_UPDATED) == 0) {
+			printf(
+			"WARNING: %s: correcting fs_sblockloc from %jd to %d\n",
+			    fs->fs_fsmnt, fs->fs_sblockloc, SBLOCK_UFS1);
+			fs->fs_sblockloc = SBLOCK_UFS1;
+		}
+		/*
+		 * Copy back UFS2 updated fields that UFS1 inspects.
+		 */
 		fs->fs_old_time = fs->fs_time;
 		fs->fs_old_cstotal.cs_ndir = fs->fs_cstotal.cs_ndir;
 		fs->fs_old_cstotal.cs_nbfree = fs->fs_cstotal.cs_nbfree;
 		fs->fs_old_cstotal.cs_nifree = fs->fs_cstotal.cs_nifree;
 		fs->fs_old_cstotal.cs_nffree = fs->fs_cstotal.cs_nffree;
-		fs->fs_maxfilesize = fs->fs_save_maxfilesize;
+		if (fs->fs_save_maxfilesize != 0)
+			fs->fs_maxfilesize = fs->fs_save_maxfilesize;
+		break;
+	case FS_UFS2_MAGIC:
+		if (fs->fs_sblockloc != SBLOCK_UFS2 &&
+		    (fs->fs_old_flags & FS_FLAGS_UPDATED) == 0) {
+			printf(
+			"WARNING: %s: correcting fs_sblockloc from %jd to %d\n",
+			    fs->fs_fsmnt, fs->fs_sblockloc, SBLOCK_UFS2);
+			fs->fs_sblockloc = SBLOCK_UFS2;
+		}
+		break;
 	}
 }
 
@@ -931,6 +950,7 @@
 ffs_sbput(void *devfd, struct fs *fs, off_t loc,
     int (*writefunc)(void *devfd, off_t loc, void *buf, int size))
 {
+	struct fs_summary_info *fs_si;
 	int i, error, blks, size;
 	uint8_t *space;
 
@@ -953,23 +973,26 @@
 		}
 	}
 	fs->fs_fmod = 0;
-#ifndef _KERNEL
-	{
-		struct fs_summary_info *fs_si;
-
-		fs->fs_time = time(NULL);
-		/* Clear the pointers for the duration of writing. */
-		fs_si = fs->fs_si;
-		fs->fs_si = NULL;
-		fs->fs_ckhash = ffs_calc_sbhash(fs);
-		error = (*writefunc)(devfd, loc, fs, fs->fs_sbsize);
-		fs->fs_si = fs_si;
-	}
-#else /* _KERNEL */
+	ffs_oldfscompat_write(fs);
+#ifdef _KERNEL
 	fs->fs_time = time_second;
+#else /* User Code */
+	fs->fs_time = time(NULL);
+#endif
+	/* Clear the pointers for the duration of writing. */
+	fs_si = fs->fs_si;
+	fs->fs_si = NULL;
 	fs->fs_ckhash = ffs_calc_sbhash(fs);
 	error = (*writefunc)(devfd, loc, fs, fs->fs_sbsize);
-#endif /* _KERNEL */
+#ifdef _KERNEL
+	/*
+	 * The kernel has done an asychronous write and will deal
+	 * with the zero'ed field when the I/O completes.
+	 */
+	if (error == EJUSTRETURN)
+		return (0);
+#endif
+	fs->fs_si = fs_si;
 	return (error);
 }
 
diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c
--- a/sys/ufs/ffs/ffs_vfsops.c
+++ b/sys/ufs/ffs/ffs_vfsops.c
@@ -2032,9 +2032,14 @@
 		panic("ffs_sbupdate: write read-only filesystem");
 	/*
 	 * We use the superblock's buf to serialize calls to ffs_sbupdate().
+	 * Copy superblock to this buffer and have it written out.
 	 */
 	sbbp = getblk(ump->um_devvp, btodb(fs->fs_sblockloc),
 	    (int)fs->fs_sbsize, 0, 0, 0);
+	UFS_LOCK(ump);
+	bcopy((caddr_t)fs, sbbp->b_data, (uint64_t)fs->fs_sbsize);
+	UFS_UNLOCK(ump);
+	fs = (struct fs *)sbbp->b_data;
 	/*
 	 * Initialize info needed for write function.
 	 */
@@ -2060,7 +2065,8 @@
 
 	devfdp = devfd;
 	ump = devfdp->ump;
-	fs = ump->um_fs;
+	bp = devfdp->sbbp;
+	fs = (struct fs *)bp->b_data;
 	/*
 	 * Writing the superblock summary information.
 	 */
@@ -2078,41 +2084,20 @@
 	/*
 	 * Writing the superblock itself. We need to do special checks for it.
 	 */
-	bp = devfdp->sbbp;
 	if (ffs_fsfail_cleanup(ump, devfdp->error))
 		devfdp->error = 0;
 	if (devfdp->error != 0) {
 		brelse(bp);
 		return (devfdp->error);
 	}
-	if (fs->fs_magic == FS_UFS1_MAGIC && fs->fs_sblockloc != SBLOCK_UFS1 &&
-	    (fs->fs_old_flags & FS_FLAGS_UPDATED) == 0) {
-		printf("WARNING: %s: correcting fs_sblockloc from %jd to %d\n",
-		    fs->fs_fsmnt, fs->fs_sblockloc, SBLOCK_UFS1);
-		fs->fs_sblockloc = SBLOCK_UFS1;
-	}
-	if (fs->fs_magic == FS_UFS2_MAGIC && fs->fs_sblockloc != SBLOCK_UFS2 &&
-	    (fs->fs_old_flags & FS_FLAGS_UPDATED) == 0) {
-		printf("WARNING: %s: correcting fs_sblockloc from %jd to %d\n",
-		    fs->fs_fsmnt, fs->fs_sblockloc, SBLOCK_UFS2);
-		fs->fs_sblockloc = SBLOCK_UFS2;
-	}
 	if (MOUNTEDSOFTDEP(ump->um_mountp))
-		softdep_setup_sbupdate(ump, (struct fs *)bp->b_data, bp);
-	UFS_LOCK(ump);
-	bcopy((caddr_t)fs, bp->b_data, (uint64_t)fs->fs_sbsize);
-	UFS_UNLOCK(ump);
-	fs = (struct fs *)bp->b_data;
-	fs->fs_fmod = 0;
-	ffs_oldfscompat_write(fs);
-	fs->fs_si = NULL;
-	/* Recalculate the superblock hash */
-	fs->fs_ckhash = ffs_calc_sbhash(fs);
+		softdep_setup_sbupdate(ump, fs, bp);
 	if (devfdp->suspended)
 		bp->b_flags |= B_VALIDSUSPWRT;
-	if (devfdp->waitfor != MNT_WAIT)
+	if (devfdp->waitfor != MNT_WAIT) {
 		bawrite(bp);
-	else if ((error = bwrite(bp)) != 0)
+		devfdp->error = EJUSTRETURN;
+	} else if ((error = bwrite(bp)) != 0)
 		devfdp->error = error;
 	return (devfdp->error);
 }