On Tue, Feb 16, 2010 at 11:52:15AM +0100, Peter Breitenlohner wrote:
> On Tue, 16 Feb 2010, Karel Zak wrote:
>
>> The number from /proc/swaps is in KiB. The swapsize= from swapon
>> verbose message is a size calculated from the 'lastpage' field from
>> swap header.
>
> Hi Karel,
>
> I'm not worried by a discrepancy of a few pages, but rather by a factor of
> two. To be on the safe side I just did this:
>
> # swapoff -av
> swapoff on /dev/sda2
> # mkswap /dev/sda2
> Setting up swapspace version 1, size = 7823648 KiB
> no label, UUID=ed23d244-73d6-4c8f-b1a2-25659c15e73b
> # swapon -av
> swapon on /dev/sda2
> swapon: /dev/sda2: found swap v1 signature string for 4 KiB PAGE_SIZE
>
> swapon: /dev/sda2: pagesize=4096, swapsize=3716452352, devsize=8011422720
> # cat /proc/swaps
> Filename Type Size Used Priority
> /dev/sda2 partition 7823644 0 -1
>
> i.e., 'mkswap' and '/proc/swaps' report a swapsize of about 8GiB whereas
> 'swapon' correctly reports devsize as 8GiB but swapsize as <4GiB. Why?
...because there was a bug in swapon. Fixed.
Karel
>From 98e9ff610ed0a3a80a7478336acff99133199375 Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@xxxxxxxxxx>
Date: Tue, 16 Feb 2010 13:48:09 +0100
Subject: [PATCH] swapon: fix swapsize calculation
Reported-by: Peter Breitenlohner <peb@xxxxxxxxxxxx>
Signed-off-by: Karel Zak <kzak@xxxxxxxxxx>
---
mount/swapon.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/mount/swapon.c b/mount/swapon.c
index 75ba865..5574f7e 100644
--- a/mount/swapon.c
+++ b/mount/swapon.c
@@ -354,7 +354,7 @@ swap_get_size(const char *hdr, const char *devname, unsigned int pagesize)
pagesize / 1024,
flip ? _("different") : _("same"));
- return (last_page + 1) * pagesize;
+ return ((unsigned long long) last_page + 1) * pagesize;
}
static int
--
1.6.6
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