Re: [PATCH] [Request for inclusion] Filesystem in Userspace

Nikita Danilov
2004-11-17T18:25:13Z

Miklos Szeredi writes:
>
> > /sys/fs used to exist for for some. Moreover, /sys/fs/foofs/ was added
> > automagically when foofs file system type was registered. But it was
> > ultimately removed, because nobody took the time to fix all races
> > between accessing /sys/fs/foofs/gadget and
> > umount/filesystem-module-unloading.
>
> I don't see why this would be any harder for filesystem code than for
> other types of drivers. Maybe someone can enlighten me.
>
> Anyway, I can try to clean it up: remove all the racy bits and keep
> what I need (which is mainly just the /sys/fs directory). Where can I
> find the most recent version of this?

It was removed at 2003.06.05, by "[fs] Remove kobject support for
filesystems" change-set (mochel@osdl.org), you can extract patch from
bitkeeper.

Reiser4 adds /sys/fs and /sys/fs/reiser4 manually (see kattr.[ch] in its
sources), and uses

ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.9-rc4/2.6.9-rc4-mm1/broken-out/reiser4-kobject-umount-race.patch
ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.9-rc4/2.6.9-rc4-mm1/broken-out/reiser4-kobject-umount-race-cleanup.patch

to avoid _some_ races (with umount), but these patches provide no
protection against races with module unloading.

>
> Thanks,
> Miklos

Nikita.