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From: Tejun Heo <tj@kernel.org>
To: Alasdair G Kergon <agk@redhat.com>
Cc: device-mapper development <dm-devel@redhat.com>,
	Milan Broz <mbroz@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	Tao Ma <tm@tao.ma>,
	linux-kernel@vger.kernel.org
Subject: Re: [dm-devel] [PATCH][RFC] dm: Do not open log and cow device read-write for read-only mappings
Date: Tue, 15 Feb 2011 16:50:18 +0100	[thread overview]
Message-ID: <20110215155018.GM3160@htj.dyndns.org> (raw)
In-Reply-To: <20110215154625.GG5825@agk-dp.fab.redhat.com>

Hello,

On Tue, Feb 15, 2011 at 03:46:25PM +0000, Alasdair G Kergon wrote:
> Exactly:)  If the filesystem permissions were what was blocking this
> (say r--) then I'd agree with EACCES.  Interpret those man pages in the
> context of 'pathname refers to a block device not a file'.
>  
> If it's EACCES, I just need to gain more privilege/capabilities and then
> repeat the system call and it could succeed.
> 
> But EROFS tells me however much extra privilege I get it's going to make
> no difference.
> 
> That's why I'm arguing EACCES is not a good error to return and EROFS is
> more appropriate.

Frankly, I don't really mind one way or the other but EROFS isn't
usually used in those areas.  It might make sense for this use case
and then there will be cases it just feels awkward.  This being a dm
thing, wouldn't it be just better to let dm massage the return value?

Thanks.

-- 
tejun

  reply	other threads:[~2011-02-15 15:50 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
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 [this message]
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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