Re: [PATCH 00/27 v6] Fix filesystem freezing deadlocks

[Al Viro <viro@ZenIV.linux.org.uk>]

On Sat, Jun 02, 2012 at 12:30:14AM +0200, Jan Kara wrote:
>   Hello,
> 
>   here is the sixth iteration of my patches to improve filesystem freezing.
> The change since last iteration is that filesystem can be frozen with open but
> unlinked files. After some thinking, I've decided that the best way to handle
> this is to block removal inside ->evict_inode() of each filesystem and use
> fs-internal level of freeze protection for that (usually I've instrumented
> filesystem's transaction system to use freeze protection). Handling
> inside VFS would be less work but the only level of freeze protection that
> has a chance of not causing deadlocks is the one used for page faults and even
> there it's not clear lock ordering would be correct wrt some fs-specific locks.
> I've converted ext2, ext4, btrfs, xfs, nilfs2, ocfs2, gfs2 and also checked
> that ext3, reiserfs, jfs should work as well (they have their internal freeze
> protection mechanisms, possibly they could be replaced by a generic one but
> given these are mostly aging filesystems, it's not a real priority IHMO).
> So finally I'm not aware of any pending issue with this patch set so if you
> have some concern, please speak up!

Could you rebase on top of e.g. -rc2 and repost?