On Wed, 9 Aug 2000, Mikael Pettersson wrote:
> Note that (inode)->i_sb is now unconditionally dereferenced.
>
> Is this a bug or aren't anonymous i_sb-less inodes permitted anymore?
The latter.
> I have a module which exports "objects" to user-space as anonymous
> files, and the underlying inodes have NULL i_sb fields.
Erm... I guess that you've never tried to do ls -l /proc/<pid>/fd for
processes blessed by such a gift?
> This breaks in test6-pre2 and later because mmap(..,MAP_SHARED,..)
> calls locks_verify_locked(), which in turn evaluates __IS_FLG()
> [via MANDATORY_LOCK and IS_MANDLOCK]. Since test6-pre2 removed
> the i_sb NULL test, this causes a NULL pointer dereference.
>
> I can work around this by attaching my inodes to a dummy superblock
> a la pipefs, but I'd rather not if I can avoid it.
Sorry. NULL ->i_sb is officially dead. Every object belongs to some
filesystem. If you want help with converting your stuff - send me an URL
to the source, OK?
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