Re: [PATCH-v4 2/7] vfs: add support for a lazytime mount option

[Theodore Ts'o <tytso@xxxxxxx>]

On Thu, Nov 27, 2014 at 06:00:16PM -0500, Theodore Ts'o wrote:
> Well.... it's not quite enough.  The problem is that for ext3 and
> ext4, the actual work of writing the inode happens in dirty_inode(),
> not in write_inode().  Which means we need to do something like this.
> 
> I'm not entirely sure whether or not this is too ugly to live;
> personally, I think my hack of handling this in update_time() might be
> preferable....

.... and this doesn't work because it breaks ext3/ext4's transaction
handling, since the writeback thread could be racing against some
transactional update of the inode.  So I don't see a way of making the
queue_io / move_expired_inodes approach to the 24 hour time being
tractable.

So the alternatives that I can see at this point is either give up on
the 24 hour timeout, or we fall back to handling this in
update_time().

                                        - Ted