From: Alasdair G Kergon <agk@redhat.com>
To: Hannes Reinecke <hare@suse.de>
Cc: Mike Snitzer <snitzer@redhat.com>, Christoph Hellwig <hch@lst.de>,
linux-block@vger.kernel.org, dm-devel@redhat.com,
Jens Axboe <axboe@kernel.dk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Alasdair G Kergon <agk@redhat.com>
Subject: Re: [dm-devel] DM's filesystem lookup in dm_get_dev_t() [was: Re: linux-next: manual merge of the device-mapper tree with Linus' tree]
Date: Tue, 22 Dec 2020 21:06:04 +0000 [thread overview]
Message-ID: <20201222210604.GD29336@agk.fab.redhat.com> (raw)
In-Reply-To: <288d1c58-c0e2-9d6f-4816-48c66536fe8b@suse.de>
On Tue, Dec 22, 2020 at 06:24:09PM +0100, Hannes Reinecke wrote:
> However, lookup_bdev() now always recurses into the filesystem, causing
> multipath to stall in an all-paths-down scenario.
I have not read the background about whatever the new problem is - I'm
jumping in cold seeing this message - but from the very beginning of
device-mapper we have strongly recommended that userspace supplies the
block device in the form MAJOR:MINOR and all our own tools do that. We
guarantee not to deadlock in these places when this is done.
We also accept the device in the form of a path name as we know there
are times when this is safe and convenient, but then we offer no
guarantees - we place the responsibility upon userspace only to do this
when it knows it is safe to do so i.e. no race and no deadlock.
Alasdair
next prev parent reply other threads:[~2020-12-22 21:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20201222095056.7a5ac0a0@canb.auug.org.au>
[not found] ` <20201222131528.GA29822@lst.de>
2020-12-22 14:53 ` DM's filesystem lookup in dm_get_dev_t() [was: Re: linux-next: manual merge of the device-mapper tree with Linus' tree] Mike Snitzer
2020-12-22 17:24 ` Hannes Reinecke
2020-12-22 21:06 ` Alasdair G Kergon [this message]
2020-12-23 8:06 ` [dm-devel] " Christoph Hellwig
2020-12-23 8:05 ` Christoph Hellwig
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