From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: get_fs_excl/put_fs_excl/has_fs_excl Date: Fri, 24 Apr 2009 20:40:47 +0200 Message-ID: <20090424184047.GA17001@lst.de> References: <20090423191817.GA22521@lst.de> <20090423192123.GL4593@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Jens Axboe Return-path: Received: from verein.lst.de ([213.95.11.210]:59140 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751832AbZDXSk4 (ORCPT ); Fri, 24 Apr 2009 14:40:56 -0400 Content-Disposition: inline In-Reply-To: <20090423192123.GL4593@kernel.dk> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu, Apr 23, 2009 at 09:21:24PM +0200, Jens Axboe wrote: > The intent was to add some sort of notification mechanism from the file > system to inform the IO scheduler (and others?) that this process is how > holding a file system wide resource. So if you have a low priority > process getting access to such a resource, you want to boost its > priority to avoid higher priority apps getting stuck beind it. Sort of a > poor mans priority inheritance. > > It would be wonderful if you could kick this process more into gear on > the fs side... So what are the calls in lock_super/unlock_super supposed to be for? ->write_super? While that can sync bits out most of the heavy lifting is now done in ->sync_fs for most filesystems. ->remount_fs? This is going to block all other I/O anyway. ->put_super? Surely not :) ext3/4 internal bits? Doesn't seem to be used for any journal related activity but mostly as protection against resizing (the whole lock_super usage in ext3/4 looks odd to me, interestingly there's none at all in ext2. Maybe someone of the extN crowd should audit and get rid of it in favour of a better fs-specific lock)