From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: IDE CDROM tail read errors Date: Tue, 04 Apr 2006 15:09:20 -0400 Message-ID: <4432C460.3080606@tmr.com> References: <1143717489.29388.32.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1143717489.29388.32.camel@localhost.localdomain> Sender: linux-kernel-owner@vger.kernel.org To: Alan Cox Cc: lkml , linux-ide@vger.kernel.org List-Id: linux-ide@vger.kernel.org Alan Cox wrote: > On Mer, 2006-03-29 at 21:11 +0200, Krzysztof Halasa wrote: >> # ls -l >> -rw-r--r-- 1 root root 687177728 Mar 29 15:51 img-15.iso >> -rw-r--r-- 1 root root 687177728 Mar 29 15:58 img-15a.iso >> >> The files are just truncated FC5d1 images (57344 bytes missing). > > The final partial read is dropped rather than partially completed. > >> # cat /sys/block/sr0/size >> 1342264 (i.e., the same as with 2.6.15 + drivers/ide) >> >> # cat /dev/cdrw > img-16a.iso >> cat: /dev/cdrw: Input/output error >> >> # cat /sys/block/sr0/size >> 1342256 (looks like it has been adjusted to .iso image size / 512 when >> the first I/O error occured) > > The SCSI layer does this bit for everyone. Its actually not libata or > the PATA drivers that have done the work here. You should find ide-scsi > does the same. > > I patched the old IDE driver a bit to try and deal with this and if you > want the patch to hack on and tidy up further feel free. > > Any hope in hell of getting this fixed? It's been broken for too long to remember. IIRC the problem is that on a read which hits EOF, instead of returning partial data read and no error, the status returned is just some "didn't work" variant and the partial read is lost. I also seem to remember that if the length of the ISO was a multiple of a magic number, 32k, or the metric hexadecimal phase of the moon, you got a clean EOF. As you say, ide-scsi fixes this, if the people who don't like it would make the alternatives work right it wouldn't be an issue... Thanks for the info.