From: Alexander Viro <aviro@redhat.com>
Subject: Re: [PATCH] NFS: Stop sillyname renames and unmounts from racing
Date: Tue, 6 Nov 2007 03:50:26 -0500
Message-ID: <20071106085026.GB5397@devserv.devel.redhat.com>
References: <472C56E5.1040901@RedHat.com> <20071105210636.2fc72e14.akpm@linux-foundation.org> <473024D2.6080105@panasas.com>
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Cc: Andrew Morton <akpm@linux-foundation.org>,
	Steve Dickson <SteveD@redhat.com>,
	Alexander Viro <aviro@redhat.com>,
	Christoph Hellwig <hch@infradead.org>,
	linux-fsdevel@vger.kernel.org,
	linux-kernel <linux-kernel@vger.kernel.org>,
	nfs@lists.sourceforge.net,
	"J. Bruce Fields" <bfields@fieldses.org>,
	Trond Myklebust <trond.myklebust@fys.uio.no>
To: Benny Halevy <bhalevy@panasas.com>
Return-path: <linux-fsdevel-owner@vger.kernel.org>
In-Reply-To: <473024D2.6080105@panasas.com>
Sender: linux-fsdevel-owner@vger.kernel.org
List-ID: <nfs.lists.sourceforge.net>

On Tue, Nov 06, 2007 at 10:24:50AM +0200, Benny Halevy wrote:

> It'd be very nice if the silly renamed inodes (with silly_count > 1) were moved
> to a different list in the first pass, under the inode_lock, and then waited on
> until silly_count <= 1 in a second pass only on the filtered list.  This will
> provide you with O(1).

It's absolutely pointless, starting with any kind of searching for inodes,
etc.  If you want fs shutdown _not_ to happen until async activity of
that kind is over, don't reinvent the sodding wheels, just tell VFS that
you are holding an active reference to superblock.  End of story.