Re: [PATCH 0/2 v2] vfs: Fix crashes when reading /proc/mounts

[Jan Kara <jack@suse.cz>]

Ping Al?

On Tue 18-12-18 14:46:40, Jan Kara wrote:
> Hello,
> 
> this is a second revision of the patch series which aims at fixing possible
> races between functions formatting output for /proc/mounts and friends and
> remount. Especially ->show_options functions of filesystems are not counting
> with the fact that options can change under them and thus races can result in
> bogus output or outright crashes (like was the case with ext4 handling of quota
> mount option, or udf could crash when printing charset name, or xfs when
> printing log device name etc.).
> 
> Since v1, I have changed the logic so that all the locking & restart magic
> happens in m_show() so that we don't bail back to traverse(), then m_start(),
> and then back to m_show(). Al, is it better this way?
> 
> I was not able to get rid of the hold_sb() helper which you didn't like much as
> namespace_sem is private to fs/namespace.c and we need to drop it after
> acquiring sb reference and before blocking on sb->s_umount semaphore. So
> hold_sb() still looked like the least painful solution.
> 
> 								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR