From: Alex Elder <elder@inktank.com>
Date: Tue, 2 Oct 2012 15:25:51 +0000 (-0500)
Subject: ceph: avoid 32-bit page index overflow
X-Git-Tag: v3.7-rc1~90^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6285bc231277419255f3498d3eb5ddc9f8e7fe79;p=pandora-kernel.git

ceph: avoid 32-bit page index overflow

A pgoff_t is defined (by default) to have type (unsigned long).  On
architectures such as i686 that's a 32-bit type.  The ceph address
space code was attempting to produce 64 bit offsets by shifting a
page's index by PAGE_CACHE_SHIFT, but the result was not what was
desired because the shift occurred before the result got promoted
to 64 bits.

Fix this by converting all uses of page->index used in this way to
use the page_offset() macro, which ensures the 64-bit result has the
intended value.

This fixes http://tracker.newdream.net/issues/3112

Reported-by:  Mohamed Pakkeer <pakkeer.mohideen@realimage.com>
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
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