From 93e4c56ecc13560e0dad69aaa67afc3ca053fb4c Mon Sep 17 00:00:00 2001
From: Wido den Hollander <wido@42on.com>
Date: Tue, 16 Jun 2020 21:50:19 +0200
Subject: [PATCH] osd: Add config option to compact OSD's object store on start

By setting this configuration option an OSD will compact it's
store's OMAP on start.

This way admin's can trigger an offline compaction by setting this
configuration value to 'true' and then restarting the OSD.

This is easier than using tools like 'ceph-kvstore-tool' with requires
more manual work on the CLI and might be more difficult for users.

Signed-off-by: Wido den Hollander <wido@42on.com>
---
 PendingReleaseNotes   | 4 ++++
 src/common/options.cc | 4 ++++
 src/osd/OSD.cc        | 4 ++++
 3 files changed, 12 insertions(+)

diff --git a/PendingReleaseNotes b/PendingReleaseNotes
index c487313ee4b34..b88f6001b8a86 100644
--- a/PendingReleaseNotes
+++ b/PendingReleaseNotes
@@ -92,3 +92,7 @@
     ceph fs required_client_features <fs name> add <feature>
     ceph fs required_client_features <fs name> rm <feature>
     ceph fs feature ls
+
+* OSD: A new configuration option ``osd_compact_on_start`` has been added which triggers
+  an OSD compaction on start. Setting this option to ``true`` and restarting an OSD
+  will result in an offline compaction of the OSD prior to booting.
diff --git a/src/common/options.cc b/src/common/options.cc
index 0d7c6880e9ed2..3ff9807aca282 100644
--- a/src/common/options.cc
+++ b/src/common/options.cc
@@ -2514,6 +2514,10 @@ std::vector<Option> get_global_options() {
     .set_default(true)
     .set_description("flush FileStore journal contents during clean OSD shutdown"),
 
+    Option("osd_compact_on_start", Option::TYPE_BOOL, Option::LEVEL_ADVANCED)
+    .set_default(false)
+    .set_description("compact OSD's object store's OMAP on start"),
+
     Option("osd_os_flags", Option::TYPE_UINT, Option::LEVEL_DEV)
     .set_default(0)
     .set_description("flags to skip filestore omap or journal initialization"),
diff --git a/src/osd/OSD.cc b/src/osd/OSD.cc
index b1a0c70dda8f2..ef1583a8ff4e2 100644
--- a/src/osd/OSD.cc
+++ b/src/osd/OSD.cc
@@ -3500,6 +3500,10 @@ int OSD::init()
 
   dout(2) << "superblock: I am osd." << superblock.whoami << dendl;
 
+  if (cct->_conf.get_val<bool>("osd_compact_on_start")) {
+    dout(2) << "compacting object store's omap" << dendl;
+    store->compact();
+  }
 
   // prime osd stats
   {
-- 
2.47.3