ocfs2: Add the 'inode64' mount option.

Now that ocfs2 limits inode numbers to 32bits, add a mount option to
disable the limit.  This parallels XFS.  64bit systems can handle the
larger inode numbers.

[ Added description of inode64 mount option in ocfs2.txt. --Mark ]

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 213bdca..d7a6f92 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -601,9 +601,10 @@
 	/*
 	 * stat(2) can't handle i_ino > 32bits, so we tell the
 	 * lower levels not to allocate us a block group past that
-	 * limit.
+	 * limit.  The 'inode64' mount option avoids this behavior.
 	 */
-	(*ac)->ac_max_block = (u32)~0U;
+	if (!(osb->s_mount_opt & OCFS2_MOUNT_INODE64))
+		(*ac)->ac_max_block = (u32)~0U;
 
 	/*
 	 * slot is set when we successfully steal inode from other nodes.