sys_swapon: separate parsing of bad blocks and extents

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>

1 files changed, 54 insertions, 29 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 10f2b33805f6..a0f39f9dc5a5 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -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))) {