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Date: Sat, 12 Aug 2006 17:23:41 -0700
From: Andrew Morton <akpm@osdl.org>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: get_swap_bio() question
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On Fri, 11 Aug 2006 23:32:17 +0200
"Rafael J. Wysocki" <rjw@sisk.pl> wrote:

> Hi,
> 
> I'm looking at get_swap_bio() in mm/page_io.c and wonder why the result of
> map_swap_page() in there is multiplied by (PAGE_SIZE >> 9).  Is it the block
> size of 512 B hardcoded?  And if so, is that actually right (I mean, aren't there
> any block devices with different block sizes)?
> 

Yep, the Linux block layer is based on a 512-bytes sector all over the
place.  Everywhere you see a sector_t, that's in units of 512-byte-sectors.