From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Thu, 7 May 2009 21:25:29 +0000 (+0200)
Subject: kill-the-bkl/reiserfs: conditionaly release the write lock on fs_changed()
X-Git-Tag: v2.6.33-rc1~360^2~18
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d663af807d8bb226394cb7e02f4665f6141a8140;p=pandora-kernel.git

kill-the-bkl/reiserfs: conditionaly release the write lock on fs_changed()

The goal of fs_changed() is to check whether the tree changed during a
schedule(). This is a BKL legacy.

A recent patch added an explicit unconditional release/reacquire of the
write lock around the cond_resched() called inside fs_changed.

But it's wasteful to unconditionally do that, we are creating superfluous
lock contention in !TIF_NEED_RESCHED case.

This patch manage that by calling reiserfs_cond_resched() from fs_changed()
which only releases the lock if we are going to reschedule.

[ Impact: inject less lock contention and tree job retries ]

Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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