Re: PATCH/FIX for drivers/cdrom/cdrom.c

[Bodo Eggert <7eggert@elstempel.de>]

Arjan van de Ven <arjan@infradead.org> wrote:
> On Wed, 2006-08-16 at 14:37 -0400, Lennart Sorensen wrote:

>> Perhaps the real problem is that some @#$@#$ user space task is
>> constantly trying to mount the disc while something else is trying to
>> write to it.
>> 
>> gnome and kde both seem very eager to implement such things.  perhaps
>> there should be a way to prevent any access by such processes while
>> writing to the disc.
> 
> there is. O_EXCL works for this.
> Any sane desktop app and cd burning app use O_EXCL already for this
> purpose...

This was discussed to death:

HAL using O_EXCL will randomly prevent burning/mounting/etc by causing a
race condition, so it can't do that. HAL not using O_EXCL will OTOH succeed
in opening despite of O_EXCL used by the burning process and thereby
prevent burning by opening a busy device. The proposed solution was
introducing O_NONE or O_HARMLESS to prevent side-effects from opening
the device.

This will, however, not prevent other users from maliciously destroying the
CD by not using O_EXCL. Chowning the device is not a real solution, since
users should be able to fusermount the CD.

Maybe it's possible to cache the result and thereby prevent repeated
opening from disturbing the burning process.
-- 
Ich danke GMX dafür, die Verwendung meiner Adressen mittels per SPF
verbreiteten Lügen zu sabotieren.

http://david.woodhou.se/why-not-spf.html