sys_swapoff: change order to match sys_swapon

The block in sys_swapon which does the final adjustments to the
swap_info_struct and to swap_list is the same as the block which
re-inserts it again at sys_swapoff on failure of try_to_unuse(), except
for the order of the operations within the lock. Since the order should
not matter, arbitrarily change sys_swapoff to match sys_swapon, in
preparation to making both share the same code.
Signed-off-by: NCesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: NEric B Munson <emunson@mgebm.net>
Acked-by: NEric B Munson <emunson@mgebm.net>
Reviewed-by: NPekka Enberg <penberg@kernel.org>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/swapfile.c

@@ -1625,6 +1625,10 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 		spin_lock(&swap_lock);
 		if (p->prio < 0)
 			p->prio = --least_priority;
+		p->flags |= SWP_WRITEOK;
+		nr_swap_pages += p->pages;
+		total_swap_pages += p->pages;
+
 		prev = -1;
 		for (i = swap_list.head; i >= 0; i = swap_info[i]->next) {
 			if (p->prio >= swap_info[i]->prio)
@@ -1636,9 +1640,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 			swap_list.head = swap_list.next = type;
 		else
 			swap_info[prev]->next = type;
-		nr_swap_pages += p->pages;
-		total_swap_pages += p->pages;
-		p->flags |= SWP_WRITEOK;
 		spin_unlock(&swap_lock);
 		goto out_dput;
 	}