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From: Tejun Heo <tj@kernel.org>
To: Milan Broz <mbroz@redhat.com>
Cc: Tao Ma <tm@tao.ma>,
	linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
	device-mapper development <dm-devel@redhat.com>
Subject: Re: [PATCH][RFC] dm: Do not open log and cow device read-write for read-only mappings
Date: Mon, 14 Feb 2011 15:09:40 +0100	[thread overview]
Message-ID: <20110214140940.GM18742@htj.dyndns.org> (raw)
In-Reply-To: <4D592AD1.6020500@redhat.com>

Hello,

On Mon, Feb 14, 2011 at 02:14:57PM +0100, Milan Broz wrote:
> > But it doesn't fix the read-only snapshot issue and I guess there will be
> > the same problem with read-only MD code too.
> > (so the 2) issue here https://lkml.org/lkml/2011/2/12/209).

So, the problem is caused by dm opening members rw even for ro
devices, right?

> I am not sure if this is complete fix... note that:
> - what happens during mirror resync and read-only log?
> - for COW, it there situation we need to update header in read-oly mode? (invalidated snap?)

But if the underlying device is marked ro, dm shouldn't update it at
all.  The device should be opened ro and ro policy should be enforced.

Thanks.

-- 
tejun

  reply	other threads:[~2011-02-14 14:09 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-13  2:02 block device read-only handling regression in 2.6.38-rc4 (bisected) Milan Broz
2011-02-13 10:58 ` [PATCH] loop: clear read-only flag in loop_clr_fd Tao Ma
2011-02-13 14:11   ` Milan Broz
2011-02-13 15:05     ` Tao Ma
2011-02-13 16:44       ` Milan Broz
2011-02-14 10:30         ` Tejun Heo
2011-02-14 11:47           ` Milan Broz
2011-02-14 13:14             ` [PATCH][RFC] dm: Do not open log and cow device read-write for read-only mappings Milan Broz
2011-02-14 14:09               ` Tejun Heo [this message]
2011-02-14 14:23                 ` Milan Broz
2011-02-14 15:44                   ` Tejun Heo
2011-02-14 23:15                     ` NeilBrown
2011-02-15  2:03                       ` [dm-devel] " Alasdair G Kergon
2011-02-15 12:17                         ` Milan Broz
2011-02-15 12:46                           ` Alasdair G Kergon
2011-02-15 15:20                             ` Tejun Heo
2011-02-15 15:46                               ` Alasdair G Kergon
2011-02-15 15:50                                 ` Tejun Heo
2011-02-15 16:05                                   ` Milan Broz
2011-02-15 16:12                                     ` Tejun Heo
2011-02-15 16:36                                       ` Milan Broz
2011-02-15 16:41                                         ` Tejun Heo
2011-02-15 16:56                                           ` Alasdair G Kergon
2011-02-16  8:46                                             ` Tejun Heo
2011-02-15 16:58                                           ` Milan Broz
2011-02-16  8:39                                             ` Tejun Heo
2011-02-15 15:16                           ` [PATCH] Return EROFS if read-only detected on block device Milan Broz
2011-02-14 14:39                 ` [dm-devel] [PATCH][RFC] dm: Do not open log and cow device read-write for read-only mappings Alasdair G Kergon
2011-02-14 14:07             ` [PATCH] loop: clear read-only flag in loop_clr_fd Tejun Heo

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