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Date:   Fri, 19 May 2023 06:11:36 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Theodore Ts'o <tytso@mit.edu>
Cc:     Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        "Darrick J. Wong" <djwong@kernel.org>, Jan Kara <jack@suse.cz>,
        linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-xfs@vger.kernel.org
Subject: Re: introduce bdev holder ops and a file system shutdown method v2
Message-ID: <20230519041136.GA10931@lst.de>
References: <20230518042323.663189-1-hch@lst.de> <ZGbYLK0lOqYqPf9O@mit.edu>
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On Thu, May 18, 2023 at 10:00:12PM -0400, Theodore Ts'o wrote:
> On Thu, May 18, 2023 at 06:23:09AM +0200, Christoph Hellwig wrote:
> > Hi all,
> > 
> > this series fixes the long standing problem that we never had a good way
> > to communicate block device events to the user of the block device.
> > 
> > It fixes this by introducing a new set of holder ops registered at
> > blkdev_get_by_* time for the exclusive holder, and then wire that up
> > to a shutdown super operation to report the block device remove to the
> > file systems.
> 
> Thanks for working on this!  Is there going to be an fstest which
> simulates a device removal while we're running fsstress or some such,
> so we can exercise full device removal path?


So the problem with xfstests is that there isn't really any generic
way to remove a block device, and even less so to put it back.

xfstests has some scsi_debug based tests, maybe I can cook something up
for that.  My testing has been with nvme, so another option would be
to add nvme-loop support to xfstests and use that.  I'll see what I can
do.