From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alessio Igor Bogani <abogani@texware.it>
Subject: [PATCH 0/1] vfs: umount_begin BKL pushdown v2
Date: Fri, 24 Apr 2009 09:06:52 +0200
Message-ID: <1240556813-8739-1-git-send-email-abogani@texware.it>
References: <20090423191934.GW1926@parisc-linux.org>
Cc: Jonathan Corbet <corbet@lwn.net>,
	=?utf-8?q?Fr=C3=A9d=C3=A9ric=20Weisbecker?= <fweisbec@gmail.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	LKML <linux-kernel@vger.kernel.org>,
	LFSDEV <linux-fsdevel@vger.kernel.org>,
	Ingo Molnar <mingo@elte.hu>, Matthew Wilcox <matthew@wil.cx>,
	Alessio Igor Bogani <abogani@texware.it>
To: Alexander Viro <viro@zeniv.linux.org.uk>
Return-path: <linux-fsdevel-owner@vger.kernel.org>
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Push the BKL acquisition from vfs to every specific filesystems
with hope that it can be eliminated in a second moment.

Filesystems, which support umount_begin(), changed by this patch
are 9p, nfs, cifs and fuse. 

Changes:
Collapsed all patches into only one as requested by Al Viro.

Moved CIFS_SB() down into BKL protected zone as requested by Matthew Wilcox.

It is hard to say if tcon (into cifs's umount_begin() function) should be
protected by BKL. Up to now umount_begin() is always called with BKL held
so in uncertainty I maintain same logic. So I moved unlock_kernel() to at
the bottom of that function as requested by Al Viro and Matthew Wilcox.

Notes:
About cifs's umount_begin() function I suspect that a deadlock or circular
locking dependency can happens into kill-the-BKL tree if that patch is applied.