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[00/13] multipathd: More map reload handling, and checkerloop work

Message ID 20241206233617.382200-1-mwilck@suse.com (mailing list archive)
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Series multipathd: More map reload handling, and checkerloop work | expand

Message

Martin Wilck Dec. 6, 2024, 11:36 p.m. UTC
This patch set goes on top of Ben's set [1] for github issue 105 [2].

The first patch implements the remark I had on patch 2 on Ben's set.

Patch 2-4 add map reload logic for the case when update_pathvec_from_dm()
detects an inconsistency: in this case, the map is now reloaded before
the checkers are actually started. If the inconsistency can't be cleared,
another attempt will be made when the checkers have finished.

Patch 5 ff. reshuffle the code in checkerloop(). There is now one function,
checker_finished(), that takes all actions that need to be done with the vecs
lock taken after the checkers have finished. checkerloop() enters this
function immediately when the checkers have finished, without dropping and
re-acquiring the vecs lock. The map reload logic is completely handled in this
function.

The various _tick() functions don't loop over mpvec any more; they are now
just called for a single mpp, and they simply return true if a map reload is
required.  The actual reload action differs: if missing_uev_wait_tick()
requests a reload, it needs to be a full update_map() (which calls
adopt_paths()), whereas in the other cases, reload_and_sync_map() is sufficient.
The last patch changes the reload action for the ghost delay tick.

Reviews & comments welcome.

Regards
Martin

[1] https://lore.kernel.org/dm-devel/20241205035638.1218953-1-bmarzins@redhat.com/
[2] https://github.com/opensvc/multipath-tools/issues/105

Martin Wilck (13):
  multipathd: don't reload map in update_mpp_prio()
  multipathd: remove dm_get_info() call from refresh_multipath()
  multipathd: allow map removal in do_sync_mpp()
  multipathd: reload maps in do_sync_mpp() if necessary
  multipathd: move yielding for waiters to start of checkerloop
  multipathd: add checker_finished()
  multipathd: move "tick" calls into checker_finished()
  multipathd: remove mpvec_garbage_collector()
  multipathd: don't call reload_and_sync_map() from
    deferred_failback_tick()
  multipathd: move retry_count_tick() into existing mpvec loop
  multipathd: don't call update_map() from missing_uev_wait_tick()
  multipathd: don't call udpate_map() from ghost_delay_tick()
  multipathd: only call reload_and_sync_map() when ghost delay expires

 multipathd/main.c | 295 +++++++++++++++++++---------------------------
 1 file changed, 120 insertions(+), 175 deletions(-)

Comments

Benjamin Marzinski Dec. 11, 2024, 12:02 a.m. UTC | #1
On Sat, Dec 07, 2024 at 12:36:04AM +0100, Martin Wilck wrote:
> This patch set goes on top of Ben's set [1] for github issue 105 [2].
> 
> The first patch implements the remark I had on patch 2 on Ben's set.
> 
> Patch 2-4 add map reload logic for the case when update_pathvec_from_dm()
> detects an inconsistency: in this case, the map is now reloaded before
> the checkers are actually started. If the inconsistency can't be cleared,
> another attempt will be made when the checkers have finished.
> 
> Patch 5 ff. reshuffle the code in checkerloop(). There is now one function,
> checker_finished(), that takes all actions that need to be done with the vecs
> lock taken after the checkers have finished. checkerloop() enters this
> function immediately when the checkers have finished, without dropping and
> re-acquiring the vecs lock. The map reload logic is completely handled in this
> function.
> 
> The various _tick() functions don't loop over mpvec any more; they are now
> just called for a single mpp, and they simply return true if a map reload is
> required.  The actual reload action differs: if missing_uev_wait_tick()
> requests a reload, it needs to be a full update_map() (which calls
> adopt_paths()), whereas in the other cases, reload_and_sync_map() is sufficient.
> The last patch changes the reload action for the ghost delay tick.
> 
> Reviews & comments welcome.

For all the patches I haven't commented on:
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>

> 
> Regards
> Martin
> 
> [1] https://lore.kernel.org/dm-devel/20241205035638.1218953-1-bmarzins@redhat.com/
> [2] https://github.com/opensvc/multipath-tools/issues/105
> 
> Martin Wilck (13):
>   multipathd: don't reload map in update_mpp_prio()
>   multipathd: remove dm_get_info() call from refresh_multipath()
>   multipathd: allow map removal in do_sync_mpp()
>   multipathd: reload maps in do_sync_mpp() if necessary
>   multipathd: move yielding for waiters to start of checkerloop
>   multipathd: add checker_finished()
>   multipathd: move "tick" calls into checker_finished()
>   multipathd: remove mpvec_garbage_collector()
>   multipathd: don't call reload_and_sync_map() from
>     deferred_failback_tick()
>   multipathd: move retry_count_tick() into existing mpvec loop
>   multipathd: don't call update_map() from missing_uev_wait_tick()
>   multipathd: don't call udpate_map() from ghost_delay_tick()
>   multipathd: only call reload_and_sync_map() when ghost delay expires
> 
>  multipathd/main.c | 295 +++++++++++++++++++---------------------------
>  1 file changed, 120 insertions(+), 175 deletions(-)
> 
> -- 
> 2.47.0