sys_swapon: separate parsing of bad blocks and extents
Cesar Eduardo Barros [Tue, 22 Mar 2011 23:33:32 +0000 (16:33 -0700)]
Move the code which parses the bad block list and the extents to a
separate function. Only code movement, no functional changes.

This change uses the fact that, after the success path, nr_good_pages ==
p->pages.

Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/swapfile.c

index 10f2b33..a0f39f9 100644 (file)
@@ -1991,6 +1991,54 @@ static unsigned long read_swap_header(struct swap_info_struct *p,
        return maxpages;
 }
 
+static int setup_swap_map_and_extents(struct swap_info_struct *p,
+                                       union swap_header *swap_header,
+                                       unsigned char *swap_map,
+                                       unsigned long maxpages,
+                                       sector_t *span)
+{
+       int i;
+       int error;
+       unsigned int nr_good_pages;
+       int nr_extents;
+
+       nr_good_pages = maxpages - 1;   /* omit header page */
+
+       for (i = 0; i < swap_header->info.nr_badpages; i++) {
+               unsigned int page_nr = swap_header->info.badpages[i];
+               if (page_nr == 0 || page_nr > swap_header->info.last_page) {
+                       error = -EINVAL;
+                       goto bad_swap;
+               }
+               if (page_nr < maxpages) {
+                       swap_map[page_nr] = SWAP_MAP_BAD;
+                       nr_good_pages--;
+               }
+       }
+
+       if (nr_good_pages) {
+               swap_map[0] = SWAP_MAP_BAD;
+               p->max = maxpages;
+               p->pages = nr_good_pages;
+               nr_extents = setup_swap_extents(p, span);
+               if (nr_extents < 0) {
+                       error = nr_extents;
+                       goto bad_swap;
+               }
+               nr_good_pages = p->pages;
+       }
+       if (!nr_good_pages) {
+               printk(KERN_WARNING "Empty swap-file\n");
+               error = -EINVAL;
+               goto bad_swap;
+       }
+
+       return nr_extents;
+
+bad_swap:
+       return error;
+}
+
 SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 {
        struct swap_info_struct *p;
@@ -2001,7 +2049,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
        int error;
        union swap_header *swap_header;
        unsigned int nr_good_pages;
-       int nr_extents = 0;
+       int nr_extents;
        sector_t span;
        unsigned long maxpages;
        unsigned char *swap_map = NULL;
@@ -2078,36 +2126,13 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
        if (error)
                goto bad_swap;
 
-       nr_good_pages = maxpages - 1;   /* omit header page */
-
-       for (i = 0; i < swap_header->info.nr_badpages; i++) {
-               unsigned int page_nr = swap_header->info.badpages[i];
-               if (page_nr == 0 || page_nr > swap_header->info.last_page) {
-                       error = -EINVAL;
-                       goto bad_swap;
-               }
-               if (page_nr < maxpages) {
-                       swap_map[page_nr] = SWAP_MAP_BAD;
-                       nr_good_pages--;
-               }
-       }
-
-       if (nr_good_pages) {
-               swap_map[0] = SWAP_MAP_BAD;
-               p->max = maxpages;
-               p->pages = nr_good_pages;
-               nr_extents = setup_swap_extents(p, &span);
-               if (nr_extents < 0) {
-                       error = nr_extents;
-                       goto bad_swap;
-               }
-               nr_good_pages = p->pages;
-       }
-       if (!nr_good_pages) {
-               printk(KERN_WARNING "Empty swap-file\n");
-               error = -EINVAL;
+       nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map,
+               maxpages, &span);
+       if (unlikely(nr_extents < 0)) {
+               error = nr_extents;
                goto bad_swap;
        }
+       nr_good_pages = p->pages;
 
        if (p->bdev) {
                if (blk_queue_nonrot(bdev_get_queue(p->bdev))) {