From bc8a309e88a86205fc3e17f06e42a2e56fc6f807 Mon Sep 17 00:00:00 2001
From: Weston Andros Adamson <dros@primarydata.com>
Date: Fri, 8 Aug 2014 11:00:54 -0400
Subject: [PATCH] nfs: fix nonblocking calls to nfs_page_group_lock

nfs_page_group_lock was calling wait_on_bit_lock even when told not to
block. Fix by first trying test_and_set_bit, followed by wait_on_bit_lock
if and only if blocking is allowed.  Return -EAGAIN if nonblocking and the
test_and_set of the bit was already locked.

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Reviewed-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Reading git-format-patch failed