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: Hugh Dickins <hugh@veritas.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 65 insertions, 81 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index c46c83d6aab0..85ff603385c3 100644
--- a/mm/swapfile.c
+++ b/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;
@@ -1553,101 +1552,86 @@ 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);
+        /* 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 */
+        if (swap_header->info.version != 1) {
+                printk(KERN_WARNING
+                       "Unable to handle swap header version %d\n",
+                       swap_header->info.version);
                 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) {
-                        printk(KERN_WARNING
-                               "Unable to handle swap header version %d\n",
-                               swap_header->info.version);
-                        error = -EINVAL;
-                        goto bad_swap;
-                }
+        }
 
-                p->lowest_bit  = 1;
-                p->cluster_next = 1;
+        p->lowest_bit  = 1;
+        p->cluster_next = 1;
 
-                /*
-                 * Find out how many pages are allowed for a single swap
-                 * device. There are two limiting factors: 1) the number of
-                 * bits for the swap offset in the swp_entry_t type and
-                 * 2) the number of bits in the a swap pte as defined by
-                 * the different architectures. In order to find the
-                 * largest possible bit mask a swap entry with swap type 0
-                 * and swap offset ~0UL is created, encoded to a swap pte,
-                 * decoded to a swp_entry_t again and finally the swap
-                 * offset is extracted. This will mask all the bits from
-                 * the initial ~0UL mask that can't be encoded in either
-                 * 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;
-                if (maxpages > swap_header->info.last_page)
-                        maxpages = swap_header->info.last_page;
-                p->highest_bit = maxpages - 1;
+        /*
+         * Find out how many pages are allowed for a single swap
+         * device. There are two limiting factors: 1) the number of
+         * bits for the swap offset in the swp_entry_t type and
+         * 2) the number of bits in the a swap pte as defined by
+         * the different architectures. In order to find the
+         * largest possible bit mask a swap entry with swap type 0
+         * and swap offset ~0UL is created, encoded to a swap pte,
+         * decoded to a swp_entry_t again and finally the swap
+         * offset is extracted. This will mask all the bits from
+         * the initial ~0UL mask that can't be encoded in either
+         * 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;
+        if (maxpages > swap_header->info.last_page)
+                maxpages = swap_header->info.last_page;
+        p->highest_bit = maxpages - 1;
 
-                error = -EINVAL;
-                if (!maxpages)
-                        goto bad_swap;
-                if (swapfilepages && maxpages > swapfilepages) {
-                        printk(KERN_WARNING
-                               "Swap area shorter than signature indicates\n");
-                        goto bad_swap;
-                }
-                if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
-                        goto bad_swap;
-                if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
-                        goto bad_swap;
+        error = -EINVAL;
+        if (!maxpages)
+                goto bad_swap;
+        if (swapfilepages && maxpages > swapfilepages) {
+                printk(KERN_WARNING
+                       "Swap area shorter than signature indicates\n");
+                goto bad_swap;
+        }
+        if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
+                goto bad_swap;
+        if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
+                goto bad_swap;
 
-                /* OK, set up the swap map and apply the bad block list */
-                swap_map = vmalloc(maxpages * sizeof(short));
-                if (!swap_map) {
-                        error = -ENOMEM;
-                        goto bad_swap;
-                }
+        /* OK, set up the swap map and apply the bad block list */
+        swap_map = vmalloc(maxpages * sizeof(short));
+        if (!swap_map) {
+                error = -ENOMEM;
+                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)
-                                error = -EINVAL;
-                        else
-                                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)
+        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) {
+                        error = -EINVAL;
                         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 (nr_good_pages) {
                 swap_map[0] = SWAP_MAP_BAD;