[PATCH V3] mke2fs: prevent creation of filesystem with unsupported revision

[Eric Sandeen <sandeen@redhat.com>]

From: Frank Sorenson <fsorenso@redhat.com>

It's a bit strange to accept revision levels higher than
the code creating the filesystem can understand, so don't
allow it.

At least the kernel will mount the fs readonly if it's too
high, but no other utility will touch it, so you can't
fix the error.

Just reject anything > EXT2_MAX_SUPP_REV at mkfs time.

Signed-off-by: Frank Sorenson <fsorenso@redhat.com>
[sandeen@redhat.com: Add more verbose commit log]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

V2: Frank did this independently, and it's better.  I forgot about
using com_err here.

V3: go back to V1's commit log for Andreas :)

--- a/misc/mke2fs.c	
+++ a/misc/mke2fs.c	
@@ -1684,6 +1684,11 @@ profile_error:
 					_("bad revision level - %s"), optarg);
 				exit(1);
 			}
+			if (r_opt > EXT2_MAX_SUPP_REV) {
+				com_err(program_name, EXT2_ET_REV_TOO_HIGH,
+					_("while trying to create revision %d"), r_opt);
+				exit(1);
+			}
 			fs_param.s_rev_level = r_opt;
 			break;
 		case 's':	/* deprecated */