Bug 202733

Summary:	isofs: Unable to mount CDs mastered with 512-byte logical sectors
Product:	File System	Reporter:	Mark (mark_k)
Component:	Other	Assignee:	fs_other
Status:	NEW ---
Severity:	normal	CC:	from_kernel
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	2.6.4	Subsystem:
Regression:	Yes	Bisected commit-id:

Description Mark 2019-03-02 21:41:29 UTC

Some ISO 9660 CD-ROMs were mastered with logical block size 512 bytes (i.e. that value is at offset 128 in the primary volume descriptor). The kernel is unable to mount such discs, reporting:
Logical zone size(512) < hardware blocksize(2048)

One example is "Fish and More Volume 3" which can be downloaded via this Google Drive link (~478MB):
https://drive.google.com/open?id=1M6HGANo3inSATuz4ozxvHOrhsO4coDKU
(That archive contains a 2352-bytes/sector .bin file. You can use iat to generate a plain ISO 9660 image from that.)

This seems to be a long-standing regression. I booted a VM from two old SuSE live CDs and tried to mount that disc.
  SuSE 9.0 (kernel 2.4.21-99-default): CD mounts successfully
  SuSE 9.1 (kernel 2.6.4-52-default): Unable to mount CD

Windows XP is able to mount the disc.

I found a few mentions of this issue:
 - linux-scsi posting from February 2001: https://www.mail-archive.com/linux-scsi@vger.kernel.org/msg00282.html
 - A King's Quest Collection CD: https://logs.scummvm.org/log.php?log=scummvm.log.17Mar2016&format=text
 - 100-CD set Digitized Sky Survey: https://groups.google.com/d/topic/novell.support.suse.linux.professional/SgN4X9FjyqU/discussion

Using the loopback device appears to be a workaround, i.e. add -o loop,block=512 to the mount command line.

Comment 1 Stephan Sokolow 2020-02-23 19:13:52 UTC

I'm deitarion from the ScummVM chatlog linked and I'd like to make a correction:

The problematic disc isn't "A King's Quest Collection CD". I was mentioning those as a "fortunately, I have other copies of King's Quest 7 that Linux has no problem mounting".

The problematic disc is a special pressing of King's Quest 7 with a modified form of the silkscreen pictured here...

https://www.mobygames.com/game/roberta-williams-kings-quest-vii-the-princeless-bride/cover-art/gameCoverId,40001/

The modifications are an extra row to the text following the curve of the disc which says, in all-caps, "For Promotional Use Only - Non-Returnable, Not For Resale." and and "S308430" tacked onto the end of the two existing lines after the "INC."

I can confirm that -o loop,block=512 on an ISO of the disc allows it to be mounted.

(Also, if this shows up as one giant block of text, your Bugzilla install's comment parser is broken. Otherwise, your comment preview function is broken.)

Comment 2 Stephan Sokolow 2020-03-26 17:48:21 UTC

> The problematic disc is a special pressing of King's Quest 7 with a modified
> form of the silkscreen pictured here...
> 
> https://www.mobygames.com/game/roberta-williams-kings-quest-vii-the-
> princeless-bride/cover-art/gameCoverId,40001/
> 
> The modifications are an extra row to the text following the curve of the
> disc which says, in all-caps, "For Promotional Use Only - Non-Returnable,
> Not For Resale." and and "S308430" tacked onto the end of the two existing
> lines after the "INC."

There's now a scan of the problematic pressing itself available to view:

https://www.mobygames.com/game/roberta-williams-kings-quest-vii-the-princeless-bride/cover-art/gameCoverId,637260/