On Wed, Aug 09, 2023 at 12:40:23AM +0100, Alasdair G Kergon wrote:

On Tue, Aug 08, 2023 at 03:45:03PM -0700, Fan Wu wrote:

quoted

On Tue, Jul 25, 2023 at 04:43:48PM -0400, Paul Moore wrote:

quoted

Where would the finalize() hook be called?

It is in the __bind function in drivers/md/dm.c, calling just before 
rcu_assign_pointer(md->map, (void *)t) which activates the inactive table.

 
That would be after the existing commit point, meaning the table swap
cannot be cancelled there, so is the finalize() you are proposing void()
i.e. designed so it always succeeds?

Alasdair

Thanks for the input.

Actually, no, the hook can be failed. I noticed the existing call before rcu_assign_pointer(md->map, (void *)t);
(https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/md/dm.c#n2255)
can also be failed so I was following the same pattern.

Could you explain a bit more about the "commit point"? It sounds like it might be better to move
the hook call just before the commit point instead.

-Fan