swapfile: remove v0 SWAP-SPACE message

The kernel has not supported v0 SWAP-SPACE since 2.5.22: I think we can
now safely drop its "version 0 swap is no longer supported" message - just
say "Unable to find swap-space signature" as usual.  This removes one
level of indentation from a stretch of sys_swapon().

I'd have liked to be specific, saying "Unable to find SWAPSPACE2
signature", but it's just too confusing that the version 1 signature shows
the number 2.

Irrelevant nearby cleanup: kmap(page) already gives page_address(page).
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/swapfile.c

@@ -1456,7 +1456,6 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 	int i, prev;
 	int error;
 	union swap_header *swap_header = NULL;
-	int swap_header_version;
 	unsigned int nr_good_pages = 0;
 	int nr_extents = 0;
 	sector_t span;
@@ -1553,26 +1552,14 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 		error = PTR_ERR(page);
 		goto bad_swap;
 	}
-	kmap(page);
-	swap_header = page_address(page);
+	swap_header = kmap(page);
 
-	if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
-		swap_header_version = 1;
-	else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
-		swap_header_version = 2;
-	else {
+	if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) {
 		printk(KERN_ERR "Unable to find swap-space signature\n");
 		error = -EINVAL;
 		goto bad_swap;
 	}
 
-	switch (swap_header_version) {
-	case 1:
-		printk(KERN_ERR "version 0 swap is no longer supported. "
-			"Use mkswap -v1 %s\n", name);
-		error = -EINVAL;
-		goto bad_swap;
-	case 2:
 	/* swap partition endianess hack... */
 	if (swab32(swap_header->info.version) == 1) {
 		swab32s(&swap_header->info.version);
@@ -1581,8 +1568,7 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 		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 */
+	/* Check the swap header's sub-version */
 	if (swap_header->info.version != 1) {
 		printk(KERN_WARNING
 		       "Unable to handle swap header version %d\n",
@@ -1608,7 +1594,8 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 	 * the swp_entry_t or the architecture definition of a
 	 * swap pte.
 	 */
-		maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1;
+	maxpages = swp_offset(pte_to_swp_entry(
+			swp_entry_to_pte(swp_entry(0, ~0UL)))) - 1;
 	if (maxpages > swap_header->info.last_page)
 		maxpages = swap_header->info.last_page;
 	p->highest_bit = maxpages - 1;
@@ -1633,21 +1620,18 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 		goto bad_swap;
 	}
 
-		error = 0;
 	memset(swap_map, 0, maxpages * sizeof(short));
 	for (i = 0; i < swap_header->info.nr_badpages; i++) {
 		int page_nr = swap_header->info.badpages[i];
-			if (page_nr <= 0 || page_nr >= swap_header->info.last_page)
+		if (page_nr <= 0 || page_nr >= swap_header->info.last_page) {
 			error = -EINVAL;
-			else
+			goto bad_swap;
+		}
 		swap_map[page_nr] = SWAP_MAP_BAD;
 	}
 	nr_good_pages = swap_header->info.last_page -
 			swap_header->info.nr_badpages -
 			1 /* header page */;
-		if (error)
-			goto bad_swap;
-	}
 
 	if (nr_good_pages) {
 		swap_map[0] = SWAP_MAP_BAD;