Merge PR ceph#24555 into master

* refs/pull/24555/head:
	doc: document optional timeout argument for `cache drop`
	mds: make timeout parameter optional for "cache drop"

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

Author: batrick

PendingReleaseNotes

@@ -13,12 +13,12 @@
   necessary for clients to give up capabilities in order for the MDS to fully
   drop its cache. This is accomplished by asking all clients to trim as many
   caps as possible. The timeout argument to the `cache drop` command controls
-  how long the MDS waits for clients to complete trimming caps. Keep in mind
-  that clients may still retain caps to open files which will prevent the
-  metadata for those files from being dropped by both the client and the MDS.
-  (This is an equivalent scenario to dropping the Linux
-  page/buffer/inode/dentry caches with some processes pinning some
-  inodes/dentries/pages in cache.)
+  how long the MDS waits for clients to complete trimming caps. This is optional
+  and is 0 by default (no timeout). Keep in mind that clients may still retain
+  caps to open files which will prevent the metadata for those files from being
+  dropped by both the client and the MDS. (This is an equivalent scenario to
+  dropping the Linux page/buffer/inode/dentry caches with some processes pinning
+  some inodes/dentries/pages in cache.)
 
 * The mon_health_preluminous_compat and mon_health_preluminous_compat_warning
   config options are removed, as the related functionality is more

src/mds/MDSDaemon.cc

@@ -245,7 +245,7 @@ void MDSDaemon::set_up_admin_socket()
                                      "show cache status");
   ceph_assert(r == 0);
   r = admin_socket->register_command("cache drop",
-                                     "cache drop name=timeout,type=CephInt,range=1",
+                                     "cache drop name=timeout,type=CephInt,range=0,req=false",
                                      asok_hook,
                                      "drop cache");
   ceph_assert(r == 0);
@@ -663,7 +663,7 @@ const std::vector<MDSDaemon::MDSCommand>& MDSDaemon::get_commands()
     MDSCommand("heap "
         "name=heapcmd,type=CephChoices,strings=dump|start_profiler|stop_profiler|release|stats",
         "show heap usage info (available only if compiled with tcmalloc)"),
-    MDSCommand("cache drop name=timeout,type=CephInt,range=1", "trim cache and optionally request client to release all caps and flush the journal"),
+    MDSCommand("cache drop name=timeout,type=CephInt,range=0,req=false", "trim cache and optionally request client to release all caps and flush the journal"),
   };
   return commands;
 };

src/mds/MDSRank.cc

@@ -276,6 +276,10 @@ class C_Drop_Cache : public MDSInternalContext {
     }
 
     void start_timer() {
+      if (!timeout) {
+        return;
+      }
+
       timer_task = new FunctionContext([this](int _) {
           timer_task = nullptr;
           complete(-ETIMEDOUT);
@@ -2486,7 +2490,7 @@ bool MDSRankDispatcher::handle_asok_command(std::string_view command,
   } else if (command == "cache drop") {
     int64_t timeout;
     if (!cmd_getval(g_ceph_context, cmdmap, "timeout", timeout)) {
-      return false;
+      timeout = 0;
     }
 
     C_SaferCond cond;
@@ -3368,7 +3372,7 @@ bool MDSRankDispatcher::handle_command(
   } else if (prefix == "cache drop") {
     int64_t timeout;
     if (!cmd_getval(g_ceph_context, cmdmap, "timeout", timeout)) {
-      return false;
+      timeout = 0;
     }
 
     JSONFormatter *f = new JSONFormatter(true);