bug: Unable to mount reiserfs from DVD+R

["Xuân Baldauf" <xuan--2006.08.31--reiserfs-list--namesys.com@baldauf.org>]

Hello,

I created backup DVDs formatted using reiserfs. However, mounting them
is not possible. If I try to mount such a DVD, I get following results:

Aug 31 01:08:18 notebook2 kernel: ReiserFS: hdc: using ordered data mode
Aug 31 01:08:18 notebook2 kernel: ReiserFS: hdc: warning: sh-458:
journal_init_dev: cannot init journal device 'unknown-block(22,0)': -30
Aug 31 01:08:18 notebook2 kernel: ReiserFS: hdc: warning: sh-462: unable
to initialize jornal device
Aug 31 01:08:18 notebook2 kernel: ReiserFS: hdc: warning: sh-2022:
reiserfs_fill_super: unable to initialize journal space

I get this error even when mounting using "-o ro,nolog".

I tracked this down to the method "journal_init_dev", which opens the
journal device with mode "blkdev_mode = FMODE_READ | FMODE_WRITE;"
except when the journal device is marked read only. However, as it
seems, my DVD burner drive is able to write DVD media (so it is not a
read-only-device, in general), but the particular DVD is only readable,
not writable. That's why (I think) the journal device itself is not
marked read only and yet "open_by_devnum(jdev, blkdev_mode);" fails.

The method "journal_init_dev" should honor the mount options "ro" or
"nolog" or both, which it currently does not (as of Linux 2.6.18-rc4).
Alternatively, method "journal_init_dev" might try to open the journal
device again (only using "read only" mode) in case the first try to open
results in -EROFS.

Xuân Baldauf.