From: Lars Ellenberg <lars.ellenberg@linbit.com>
Date: Wed, 15 Dec 2010 22:21:39 +0000 (+0100)
Subject: drbd: bitmap: don't count unused bits (fix non-terminating resync)
X-Git-Tag: v2.6.39-rc1~37^2~60
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7777a8ba1fc980e5edfe492ebf5a1676497b8db2;p=pandora-kernel.git

drbd: bitmap: don't count unused bits (fix non-terminating resync)

We trusted the on-disk bitmap to have unused bits cleared.
In case that is not true for whatever reason,
and we take a code path where the unused bits don't get cleared
elsewhere (bm_clear_surplus is not called), we may miscount the bits,
and get confused during resync, waiting for bits to get cleared that we
don't even use: the resync process would not terminate.

Fix this by masking out unused bits in __bm_count_bits.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
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