[PATCH 06/14] sysfs: Rewrite sysfs_get_dentry

[Eric W. Biederman]

Tejun Heo <htejun at gmail.com> writes:

> Hmmm... I think we can live with a bit of complexity in
> sysfs_get_dentry().  It's very well localized and not even long.  I have
> been trying hard to untangle sysfs internals from vfs and have a bit of
> resistance against going back.  But, then again, if we can achieve
> something better and simpler, why not?

Right now my real challenge is untangling sysfs_move_dir.  In the
case of multiple mounts of the sysfs tree.

My practical problem is that I need to hold a lock for the sysfs
dirents and while that lock is held I need to call sysfs_get_dentry
for the destination directory once for each superblock.

It might be that some kind of reader-writer lock strategy is what
I need to untangle this mess.  Rather then making changing to i_mutex.
All I know is at the moment it is taking a lot of code reading and
brain storm to come of with something that is easy to maintain.

Eric