From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 4/5] block: make blkdev_get/put() handle exclusive access Date: Wed, 3 Nov 2010 12:10:59 -0400 Message-ID: <20101103161059.GA13621@infradead.org> References: <1288628129-12811-1-git-send-email-tj@kernel.org> <1288628129-12811-5-git-send-email-tj@kernel.org> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <1288628129-12811-5-git-send-email-tj@kernel.org> Sender: reiserfs-devel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tejun Heo Cc: axboe@kernel.dk, hch@infradead.org, linux-kernel@vger.kernel.org, petero2@telia.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, jack@suse.cz, akpm@linux-foundation.org, adilger.kernel@dilger.ca, tytso@mit.edu, mfasheh@suse.com, joel.becker@oracle.com, aelder@sgi.com, dm-devel@redhat.com, drbd-dev@lists.linbit.com, neilb@suse.de, leochen@broadcom.com, sbranden@broadcom.com, chris.mason@oracle.com, swhiteho@redhat.com, shaggy@linux.vnet.ibm.com, joern@logfs.org, konishi.ryusuke@lab.ntt.co.jp, reiserfs-devel@vger.kernel.org, viro@zeniv.linux.org.uk On Mon, Nov 01, 2010 at 05:15:28PM +0100, Tejun Heo wrote: > * blkdev_get() is extended to include exclusive access management. > @holder argument is added and, if is @FMODE_EXCL specified, it will > gain exclusive access atomically w.r.t. other exclusive accesses. > > * blkdev_put() is similarly extended. It now takes @mode argument and > if @FMODE_EXCL is set, it releases an exclusive access. Also, when > the last exclusive claim is released, the holder/slave symlinks are > removed automatically. Could we get rid of FMODE_EXCL and just make a non-NULL holder field mean to open it exlusively (and pass a holder to the blkdev_put to release it)? > * bd_link_disk_holder() remains the same but bd_unlink_disk_holder() > is no longer necessary and removed. That's a rather asymetric interface. What about having blkdev_get_stacked that require a gendisk as holder and set up the links underneath? > open_bdev_exclusive() and open_by_devnum() can use further cleanup - > rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop > special features. Well, let's leave them for another day. s/blkdev_get_by_devt/blkdev_get_by_dev/ And yes, that rename is a good idea and should go in ASAP after this patch.