doc: add the reject the clone when threads are not available feature in the document

Fixes: https://tracker.ceph.com/issues/59714
Signed-off-by: Neeraj Pratap Singh <neesingh@redhat.com>

diff --git a/PendingReleaseNotes b/PendingReleaseNotes
index 0ecec83ec81f9e81fe7feedcf5abf2202bc1dc9a..54ac2d7e192cf77ed31efe6370a323c72d71ef91 100644 (file)
--- a/PendingReleaseNotes
+++ b/PendingReleaseNotes
@@ -131,6 +131,15 @@ CephFS: Disallow delegating preallocated inode ranges to clients. Config
   ``rgw_topic_require_publish_policy`` can be enabled to deny ``sns:Publish``
   permissions unless explicitly granted by topic policy.
 
+* CephFS: The `subvolume snapshot clone` command now depends on the config option
+  `snapshot_clone_no_wait` which is used to reject the clone operation when
+  all the cloner threads are busy. This config option is enabled by default which means 
+  that if no cloner threads are free, the clone request errors out with EAGAIN.
+  The value of the config option can be fetched by using:
+   `ceph config get mgr mgr/volumes/snapshot_clone_no_wait`
+  and it can be disabled by using:
+   `ceph config set mgr mgr/volumes/snapshot_clone_no_wait false`
+
 >=18.0.0
 
 * The RGW policy parser now rejects unknown principals by default. If you are

diff --git a/doc/cephfs/fs-volumes.rst b/doc/cephfs/fs-volumes.rst
index 1e7adf3a03d40a10e1008d8ae9dcfb772497e26a..dc9be8379aa39592915fa4ae67dd56b4160a1663 100644 (file)
--- a/doc/cephfs/fs-volumes.rst
+++ b/doc/cephfs/fs-volumes.rst
@@ -579,6 +579,8 @@ To initiate a clone operation use:
 
    ceph fs subvolume snapshot clone <vol_name> <subvol_name> <snap_name> <target_subvol_name>
 
+.. note:: ``subvolume snapshot clone`` command depends upon the above mentioned config option ``snapshot_clone_no_wait``
+
 If a snapshot (source subvolume) is a part of non-default group, the group name needs to be specified:
 
 .. prompt:: bash #
@@ -597,12 +599,6 @@ Similar to specifying a pool layout when creating a subvolume, pool layout can b
 
    ceph fs subvolume snapshot clone <vol_name> <subvol_name> <snap_name> <target_subvol_name> --pool_layout <pool_layout>
 
-Configure the maximum number of concurrent clones. The default is 4:
-
-.. prompt:: bash #
-
-   ceph config set mgr mgr/volumes/max_concurrent_clones <value>
-
 To check the status of a clone operation use:
 
 .. prompt:: bash #
@@ -728,6 +724,29 @@ On successful cancellation, the cloned subvolume is moved to the ``canceled`` st
 
 .. note:: The canceled cloned may be deleted by supplying the ``--force`` option to the `fs subvolume rm` command.
 
+Configurables
+~~~~~~~~~~~~~
+
+Configure the maximum number of concurrent clone operations. The default is 4:
+
+.. prompt:: bash #
+
+   ceph config set mgr mgr/volumes/max_concurrent_clones <value>
+
+Configure the snapshot_clone_no_wait option :
+
+.. prompt:: bash #
+
+   ``snapshot_clone_no_wait`` config option is used to reject the clone creation request when the cloner threads 
+   ( which can be configured using above option i.e. ``max_concurrent_clones``) are not available.
+   It is enabled by default i.e. the value set is True, whereas it can be configured by using below command.
+
+   ceph config set mgr mgr/volumes/snapshot_clone_no_wait <bool>
+
+   The current value of ``snapshot_clone_no_wait`` can be fetched by using below command.
+
+   ceph config get mgr mgr/volumes/snapshot_clone_no_wait
+
 
 .. _subvol-pinning: