linux-kernel - [PATCHv2 15/24] sys_swapon: move setting of swapfilepages near use

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Message-Id: <1299343345-3984-16-git-send-email-cesarb@cesarb.net>
Date:	Sat,  5 Mar 2011 13:42:16 -0300
From:	Cesar Eduardo Barros <cesarb@...arb.net>
To:	linux-mm@...ck.org
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Minchan Kim <minchan.kim@...il.com>,
	Jens Axboe <jaxboe@...ionio.com>, linux-kernel@...r.kernel.org,
	Eric B Munson <emunson@...bm.net>,
	Cesar Eduardo Barros <cesarb@...arb.net>
Subject: [PATCHv2 15/24] 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@...arb.net>
Tested-by: Eric B Munson <emunson@...bm.net>
Acked-by: Eric B Munson <emunson@...bm.net>
---
 mm/swapfile.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 058cf1b..f3f413b 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");
-- 
1.7.4

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