From: Joe Thornber <ejt@redhat.com>
Date: Wed, 20 Mar 2013 17:21:25 +0000 (+0000)
Subject: dm thin: fix non power of two discard granularity calc
X-Git-Tag: v3.9-rc4~20^2~8
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=58051b94e05a59c4d34f9f1a441af40894817c59;p=pandora-kernel.git

dm thin: fix non power of two discard granularity calc

Fix a discard granularity calculation to work for non power of 2 block sizes.

In order for thinp to passdown discard bios to the underlying data
device, the data device must have a discard granularity that is a
factor of the thinp block size.  Originally this check was done by
using bitops since the block_size was known to be a power of two.

Introduced by commit f13945d75730081830b6f3360266950e2b7c9067
("dm thin: support a non power of 2 discard_granularity").

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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