From: Mike Snitzer <snitzer@redhat.com>

Date: Fri, 25 Jun 2021 15:18:59 -0400

Subject: [PATCH] dm writecache: add "cleaner" and "max_age" to Documentation

Git-commit: cd039afa0ad86e1f01921cc5abf7f80d2449543a

Patch-mainline: v5.14-rc1

References: git-fixes

Backfill missing Documentation.

Fixes: 93de44eb3fc8 ("dm writecache: implement the "cleaner" policy")

Fixes: 3923d4854e18 ("dm writecache: implement gradual cleanup")

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Acked-by: Hannes Reinecke <hare@suse.com>

---

 .../admin-guide/device-mapper/writecache.rst    | 17 +++++++++++++++++

 1 file changed, 17 insertions(+)

diff --git a/Documentation/admin-guide/device-mapper/writecache.rst b/Documentation/admin-guide/device-mapper/writecache.rst

index dce0184e07ca..c181f26af769 100644

--- a/Documentation/admin-guide/device-mapper/writecache.rst

+++ b/Documentation/admin-guide/device-mapper/writecache.rst

@@ -53,6 +53,21 @@ Constructor parameters:

 		- some underlying devices perform better with fua, some

 		  with nofua. The user should test it

+	cleaner

+		when this option is activated (either in the constructor

+		arguments or by a message), the cache will not promote

+		new writes (however, writes to already cached blocks are

+		promoted, to avoid data corruption due to misordered

+		writes) and it will gradually writeback any cached

+		data. The userspace can then monitor the cleaning

+		process with "dmsetup status". When the number of cached

+		blocks drops to zero, userspace can unload the

+		dm-writecache target and replace it with dm-linear or

+		other targets.

+	max_age n

+		specifies the maximum age of a block in milliseconds. If

+		a block is stored in the cache for too long, it will be

+		written to the underlying device and cleaned up.

 Status:

 1. error indicator - 0 if there was no error, otherwise error number

@@ -77,3 +92,5 @@ Messages:

 		5. resume the device, so that it will use the linear

 		   target

 		6. the cache device is now inactive and it can be deleted

+	cleaner

+		See above "cleaner" constructor documentation.

-- 

2.29.2