mm: try both endianess when checking for endianess

When checking for the swap header try byteswapping the endianess dependent
fields to allow the swap partition to be shared between big & little endian
systems.

Signed-off-by: Chris Dearman <chris@mips.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/swapfile.c

@@ -1582,6 +1582,14 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 		error = -EINVAL;
 		goto bad_swap;
 	case 2:
+		/* swap partition endianess hack... */
+		if (swab32(swap_header->info.version) == 1) {
+			swab32s(&swap_header->info.version);
+			swab32s(&swap_header->info.last_page);
+			swab32s(&swap_header->info.nr_badpages);
+			for (i = 0; i < swap_header->info.nr_badpages; i++)
+				swab32s(&swap_header->info.badpages[i]);
+		}
 		/* Check the swap header's sub-version and the size of
                    the swap file and bad block lists */
 		if (swap_header->info.version != 1) {