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>

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 61a604c..4dade51 100644 (file)
--- 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");