From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: Re: For the condition "file->f_mode", when it failed, it should return EACCES rather than EBADF. Date: Tue, 5 Feb 2013 21:19:03 +0100 Message-ID: <20130205201903.GY15092@kernel.dk> References: <2013020410070150879010@gmail.com> <20130205132117.GU15092@kernel.dk> <201302052339385271010@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel , linux-fsdevel To: majianpeng Return-path: Received: from merlin.infradead.org ([205.233.59.134]:36350 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755223Ab3BEUUC (ORCPT ); Tue, 5 Feb 2013 15:20:02 -0500 Content-Disposition: inline In-Reply-To: <201302052339385271010@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Feb 05 2013, majianpeng wrote: > >On Sun, Feb 03 2013, majianpeng wrote: > >> Hi all, > >> When I wanted to do discard operations,but i set the openflag was O_RDONLY,it returned a EBADF rather than EACCES or EPERM. > >> I searched the code and found: > >> >case BLKDISCARD: > >> >case BLKSECDISCARD: { > >> > uint64_t range[2]; > >> > >> > if (!(mode & FMODE_WRITE)) > >> > return -EBADF; > >> Initial i thought there was error.But i searched all code of kernel and found some places like this. > >> > >> The description of EBADF is "Bad file numbe". There are some places where returned EBADF like, > >> >if (!f.file) > >> > return -EBADF; > >> > >> So i think for checking file->f_mode when failed, it should return EACCESS. > > > >But that would break the ABI at this point. I agree with you, though, > >EBADF is not the right error for this case. > > > >-- > >Jens Axboe > > > Sorry, can you explain in detail? Why can it break the ABI ? Applications already depending on EBADF being returned for attempt to discard on a file descriptor not opened for write. Granted it's a slim possiblity, but it exists. -- Jens Axboe