sys_swapon: move setting of swapfilepages near use

There is no reason I can see to read inode->i_size long before it is
needed. Move its read to just before it is needed, to reduce the
variable lifetime.

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: Jesper Juhl <jj@chaosbits.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, 1 insertions, 2 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 61a604c12a96..4dade515b086 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1975,8 +1975,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
         if (unlikely(error))
                 goto bad_swap;
 
-        swapfilepages = i_size_read(inode) >> PAGE_SHIFT;
-
         /*
          * Read the swap header.
          */
@@ -2045,6 +2043,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
         error = -EINVAL;
         if (!maxpages)
                 goto bad_swap;
+        swapfilepages = i_size_read(inode) >> PAGE_SHIFT;
         if (swapfilepages && maxpages > swapfilepages) {
                 printk(KERN_WARNING
                        "Swap area shorter than signature indicates\n");