diff --git a/include/xfs_mount.h b/include/xfs_mount.h
index dc2206de..f3c03833 100644
--- a/include/xfs_mount.h
+++ b/include/xfs_mount.h
@@ -207,6 +207,7 @@ __XFS_UNSUPP_FEAT(wsync)
 __XFS_UNSUPP_FEAT(noattr2)
 __XFS_UNSUPP_FEAT(ikeep)
 __XFS_UNSUPP_FEAT(swalloc)
+__XFS_UNSUPP_FEAT(small_inums)
 __XFS_UNSUPP_FEAT(readonly)
 
 /* Operational mount state flags */
diff --git a/libxfs/init.c b/libxfs/init.c
index 94f70429..5a3bf169 100644
--- a/libxfs/init.c
+++ b/libxfs/init.c
@@ -425,14 +425,13 @@ libxfs_init(libxfs_init_t *a)
  */
 static int
 rtmount_init(
-	xfs_mount_t	*mp,	/* file system mount structure */
-	int		flags)
+	xfs_mount_t	*mp)	/* file system mount structure */
 {
 	struct xfs_buf	*bp;	/* buffer for last block of subvolume */
 	xfs_daddr_t	d;	/* address of last block of subvolume */
 	int		error;
 
-	if (!xfs_has_realtime(mp))
+	if (mp->m_sb.sb_rblocks == 0)
 		return 0;
 
 	if (xfs_has_reflink(mp)) {
@@ -490,13 +489,21 @@ rtmount_init(
 
 /*
  * Set parameters for inode allocation heuristics, taking into account
- * filesystem size.
+ * filesystem size and inode32/inode64 mount options; i.e. specifically
+ * whether or not XFS_MOUNT_SMALL_INUMS is set.
+ *
+ * Inode allocation patterns are altered only if inode32 is requested
+ * (XFS_MOUNT_SMALL_INUMS), and the filesystem is sufficiently large.
+ * If altered, XFS_MOUNT_32BITINODES is set as well.
  *
  * An agcount independent of that in the mount structure is provided
  * because in the growfs case, mp->m_sb.sb_agcount is not yet updated
  * to the potentially higher ag count.
  *
  * Returns the maximum AG index which may contain inodes.
+ *
+ * NOTE: userspace has no concept of "inode32" and so xfs_has_small_inums
+ * is always false, and much of this code is a no-op.
  */
 xfs_agnumber_t
 xfs_set_inode_alloc(
@@ -526,11 +533,19 @@ xfs_set_inode_alloc(
 		max_metadata = agcount;
 	}
 
-	/* Get the last possible inode in an AG. */
-	agino = XFS_AGB_TO_AGINO(mp, sbp->sb_agblocks - 1);
+	/* Get the last possible inode in the filesystem */
+	agino =	XFS_AGB_TO_AGINO(mp, sbp->sb_agblocks - 1);
+	ino = XFS_AGINO_TO_INO(mp, agcount - 1, agino);
 
-	/* There is no inode32 mount option in userspace, so clear it. */
-	xfs_clear_inode32(mp);
+	/*
+	 * If user asked for no more than 32-bit inodes, and the fs is
+	 * sufficiently large, set XFS_MOUNT_32BITINODES if we must alter
+	 * the allocator to accommodate the request.
+	 */
+	if (xfs_has_small_inums(mp) && ino > XFS_MAXINUMBER_32)
+		xfs_set_inode32(mp);
+	else
+		xfs_clear_inode32(mp);
 
 	for (index = 0; index < agcount; index++) {
 		struct xfs_perag	*pag;
@@ -815,7 +830,7 @@ libxfs_mount(
 	}
 
 	/* Initialize realtime fields in the mount structure */
-	if (rtmount_init(mp, flags)) {
+	if (rtmount_init(mp)) {
 		fprintf(stderr, _("%s: realtime device init failed\n"),
 			progname);
 			return NULL;
diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c
index 2a9e8c98..6c5ce3ea 100644
--- a/libxfs/rdwr.c
+++ b/libxfs/rdwr.c
@@ -214,7 +214,7 @@ libxfs_bcompare(struct cache_node *node, cache_key_t key)
 	"%lx: Badness in key lookup (length)\n"
 	"bp=(bno 0x%llx, len %u bytes) key=(bno 0x%llx, len %u bytes)\n",
 				pthread_self(),
-				(unsigned long long)xfs_buf_daddr(bp),
+				xfs_buf_daddr(bp),
 				BBTOB(bp->b_length),
 				(unsigned long long)bkey->blkno,
 				BBTOB(bkey->bblen));
@@ -833,14 +833,15 @@ libxfs_bwrite(
 			fprintf(stderr,
 	_("%s: write verifier failed on %s bno 0x%llx/0x%x\n"),
 				__func__, bp->b_ops->name,
-				(long long)xfs_buf_daddr(bp), bp->b_length);
+				xfs_buf_daddr(bp), bp->b_length);
 			return bp->b_error;
 		}
 	}
 
 	if (!(bp->b_flags & LIBXFS_B_DISCONTIG)) {
 		bp->b_error = __write_buf(fd, bp->b_addr, BBTOB(bp->b_length),
-				    LIBXFS_BBTOOFF64(xfs_buf_daddr(bp)), bp->b_flags);
+				    LIBXFS_BBTOOFF64(xfs_buf_daddr(bp)),
+				    bp->b_flags);
 	} else {
 		int	i;
 		void	*buf = bp->b_addr;
@@ -861,7 +862,7 @@ libxfs_bwrite(
 		fprintf(stderr,
 	_("%s: write failed on %s bno 0x%llx/0x%x, err=%d\n"),
 			__func__, bp->b_ops ? bp->b_ops->name : "(unknown)",
-			(long long)xfs_buf_daddr(bp), bp->b_length, -bp->b_error);
+			xfs_buf_daddr(bp), bp->b_length, -bp->b_error);
 	} else {
 		bp->b_flags |= LIBXFS_B_UPTODATE;
 		bp->b_flags &= ~(LIBXFS_B_DIRTY | LIBXFS_B_UNCHECKED);