Merge PR ceph#58582 into main

* refs/pull/58582/head:
	test: add a test for `fs set down` on online cluster
	mon: fix `fs set down` to adjust max_mds only when cluster is not down

Reviewed-by: Dhairya Parmar <[email protected]>
Reviewed-by: Patrick Donnelly <[email protected]>

Author: batrick

qa/workunits/cephtool/test.sh

@@ -976,6 +976,11 @@ function test_mon_mds()
   ceph fs set $FS_NAME cluster_down true
   ceph fs set $FS_NAME cluster_down false
 
+  ceph fs set $FS_NAME max_mds 2
+  ceph fs get $FS_NAME | expect_true grep -P -q 'max_mds\t2'
+  ceph fs set $FS_NAME down false
+  ceph fs get $FS_NAME | expect_true grep -P -q 'max_mds\t2'
+
   ceph mds compat rm_incompat 4
   ceph mds compat rm_incompat 4
 

src/mon/FSCommands.cc

@@ -598,6 +598,11 @@ int FileSystemCommandHandler::set_val(Monitor *mon, FSMap& fsmap, MonOpRequestRe
 
       ss << fsp->get_mds_map().get_fs_name();
 
+      if (!is_down && fsp->get_mds_map().get_max_mds() > 0) {
+        ss << " is already online";
+        return 0;
+      }
+
       modify_filesystem(fsmap, fsv,
           [is_down](auto&& fs)
       {