linux-kernel - Re: [PATCH v2 6/8] bdev: add open

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Message-ID: <20191024131905.GM938@kitsune.suse.cz>
Date:   Thu, 24 Oct 2019 15:19:05 +0200
From:   Michal Suchánek <msuchanek@...e.de>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Christoph Hellwig <hch@...radead.org>, linux-scsi@...r.kernel.org,
        Jonathan Corbet <corbet@....net>, Jens Axboe <axboe@...nel.dk>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Eric Biggers <ebiggers@...gle.com>,
        "J. Bruce Fields" <bfields@...hat.com>,
        Benjamin Coddington <bcodding@...hat.com>,
        Hannes Reinecke <hare@...e.com>,
        Omar Sandoval <osandov@...com>, Ming Lei <ming.lei@...hat.com>,
        Damien Le Moal <damien.lemoal@....com>,
        Bart Van Assche <bvanassche@....org>,
        Tejun Heo <tj@...nel.org>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2 6/8] bdev: add open_finish.

On Thu, Oct 24, 2019 at 06:12:54AM -0700, Matthew Wilcox wrote:
> On Thu, Oct 24, 2019 at 10:55:14AM +0200, Michal Suchánek wrote:
> > On Wed, Oct 23, 2019 at 07:22:32PM -0700, Christoph Hellwig wrote:
> > > On Wed, Oct 23, 2019 at 02:52:45PM +0200, Michal Suchanek wrote:
> > > > Opening a block device may require a long operation such as waiting for
> > > > the cdrom tray to close. Performing this operation with locks held locks
> > > > out other attempts to open the device. These processes waiting to open
> > > > the device are not killable.
> 
> You can use mutex_lock_killable() to fix that.
> 

That solves only half of the problem.

It still does not give access to the device to processes that open with
O_NONBLOCK.

Thanks

Michal