Merge pull request ceph#60510 from Matan-B/wip-matanb-backfill-crimson-docs

doc/dev/crimson: Add BackfillMachine state graph

Reviewed-by: Samuel Just <[email protected]>
Reviewed-by: Anthony D'Atri <[email protected]>

Author: Matan-B

doc/dev/crimson/backfillmachine.rst

@@ -0,0 +1,26 @@
+===============
+BackfillMachine
+===============
+
+
+In Crimson, backfill is implemented with `Boost State Chart <https://www.boost.org/doc/libs/1_86_0/libs/statechart/doc/>`_.
+
+.. //TODO: Once the implementation is settled:
+..         * Explain exceptional states once we finish working on this code
+..         * Explain example happy path flow (code walkthorugh?)
+..         * https://tracker.ceph.com/issues/68728
+
+A sample of the recent state model:
+
+.. note:: ``Cancelled`` and ``Crushed`` states are not included in the
+          following graph in order to make it easier to follow:
+
+          * **Any** state is able to transit into ``Crushed``.
+
+          * **Any** state (except from ``Initial`` and ``Waiting``) can transit into ``Cancelled``
+
+.. image:: crimson_backfillmachine.svg
+
+
+In similarly to :doc:`/dev/peering` a copy of the latest BackfillMachine
+state model can be genereated using the `gen_state_diagram.py <https://github.com/ceph/ceph/blob/master/doc/scripts/gen_state_diagram.py>`_

doc/dev/crimson/crimson_backfillmachine.svg

@@ -7,7 +7,11 @@ Crimson developer documentation
 .. rubric:: Contents
 
 .. toctree::
-   :glob:
-
-   *
+   :maxdepth: 1
 
+   Crimson <crimson>
+   OSDState <osd>
+   The ClientRequest Pipeline <pipeline>
+   Error Handling <error-handling>
+   BackfillMachine <backfillmachine>
+   PoseidonStore <poseidonstore>

doc/dev/crimson/index.rst

@@ -1,5 +1,5 @@
-osd
-===
+OSDState
+========
 
 .. graphviz::