From: Josef Bacik <jbacik@fusionio.com>
Date: Wed, 1 Aug 2012 19:36:24 +0000 (-0400)
Subject: Btrfs: barrier before waitqueue_active
X-Git-Tag: v3.6-rc4~6^2~12
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=66657b318e0e443ada229fccd40c8be86cfebdbf;p=pandora-kernel.git

Btrfs: barrier before waitqueue_active

We need a barrir before calling waitqueue_active otherwise we will miss
wakeups.  So in places that do atomic_dec(); then atomic_read() use
atomic_dec_return() which imply a memory barrier (see memory-barriers.txt)
and then add an explicit memory barrier everywhere else that need them.
Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
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