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Date: Fri, 26 Oct 2012 17:23:12 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Mikulas Patocka <mpatocka@redhat.com>, Al Viro <viro@ZenIV.linux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>, Peter Zijlstra <peterz@infradead.org>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@elte.hu>,
        Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
        Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
        Anton Arapov <anton@redhat.com>, linux-kernel@vger.kernel.org,
        Thomas Gleixner <tglx@linutronix.de>
Subject: mark_files_ro && sb_end_write
Message-ID: <20121026152312.GA13725@redhat.com>
References: <1350650286.30157.28.camel@twins> <Pine.LNX.4.64.1210191058060.13298@file.rdu.redhat.com> <1350668451.2768.60.camel@twins> <Pine.LNX.4.64.1210191758570.12753@file.rdu.redhat.com> <20121024030845.GT4291@dastard> <Pine.LNX.4.64.1210251008330.1849@file.rdu.redhat.com> <20121025234048.GH29378@dastard> <20121026120605.GA23545@redhat.com> <Pine.LNX.4.64.1210260900170.24474@file.rdu.redhat.com> <20121026141238.GA28443@redhat.com>
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On 10/26, Oleg Nesterov wrote:
>
> As for the changing fs/namespace.c to use percpu_rwsem, I am not sure
> it is that simple and even worthwhile but I won't argue, I do not
> pretend I understand this code.

BTW, speaking about these counters...

Is mark_files_ro()->mnt_drop_write_file() properly balanced?
__mnt_drop_write() looks fine, but sb_end_write?

Oleg.