From mboxrd@z Thu Jan 1 00:00:00 1970 From: Milan Broz 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 17:36:31 +0100 Message-ID: <4D5AAB8F.50901@redhat.com> References: <4D5A6EF4.3030905@redhat.com> <20110215124629.GF5825@agk-dp.fab.redhat.com> <20110215152033.GK3160@htj.dyndns.org> <20110215154625.GG5825@agk-dp.fab.redhat.com> <20110215155018.GM3160@htj.dyndns.org> <4D5AA45C.7050600@redhat.com> <20110215161228.GN3160@htj.dyndns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110215161228.GN3160@htj.dyndns.org> Sender: linux-kernel-owner@vger.kernel.org To: Tejun Heo Cc: Alasdair G Kergon , device-mapper development , Jens Axboe , Tao Ma , linux-kernel@vger.kernel.org List-Id: dm-devel.ids On 02/15/2011 05:12 PM, Tejun Heo wrote: > On Tue, Feb 15, 2011 at 05:05:48PM +0100, Milan Broz wrote: >> On 02/15/2011 04:50 PM, Tejun Heo wrote: >>>> 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? >> >> It is not DM thing. That code was checking for generic block device. >> No DM there (it was from cryptsetup code but not related to DM part). > > Hmmm... I'm confused now. Where was that -EROFS from then? I don't > recall changing -EROFS to -EACCES. What did I miss? Well, I am also not sure about that. But the problem is that read-write open fails now while it worked before. (TBH I have no idea when that EROFS fallback worked - because the code opened device RW, issued EROGET ioctl and set read-only... for years.) Anyway I think EROFS is used on block devices, just grep kernel source. Milan