Merge branch 'linus' into core/locking

Refresh the topic.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 17 insertions, 3 deletions

diff --git a/include/uapi/linux/dm-log-userspace.h b/include/uapi/linux/dm-log-userspace.h
index 0678c2adc421..0fa0d9ef06a5 100644
--- a/include/uapi/linux/dm-log-userspace.h
+++ b/include/uapi/linux/dm-log-userspace.h
@@ -201,11 +201,18 @@
  * int (*flush)(struct dm_dirty_log *log);
  *
  * Payload-to-userspace:
- *	None.
+ *	If the 'integrated_flush' directive is present in the constructor
+ *	table, the payload is as same as DM_ULOG_MARK_REGION:
+ *		uint64_t [] - region(s) to mark
+ *	else
+ *		None
  * Payload-to-kernel:
  *	None.
  *
- * No incoming or outgoing payload.  Simply flush log state to disk.
+ * If the 'integrated_flush' option was used during the creation of the
+ * log, mark region requests are carried as payload in the flush request.
+ * Piggybacking the mark requests in this way allows for fewer communications
+ * between kernel and userspace.
  *
  * When the request has been processed, user-space must return the
  * dm_ulog_request to the kernel - setting the 'error' field and clearing
@@ -385,8 +392,15 @@
  *	version 2:  DM_ULOG_CTR allowed to return a string containing a
  *	            device name that is to be registered with DM via
  *	            'dm_get_device'.
+ *	version 3:  DM_ULOG_FLUSH is capable of carrying payload for marking
+ *		    regions.  This "integrated flush" reduces the number of
+ *		    requests between the kernel and userspace by effectively
+ *		    merging 'mark' and 'flush' requests.  A constructor table
+ *		    argument ('integrated_flush') is required to turn this
+ *		    feature on, so it is backwards compatible with older
+ *		    userspace versions.
  */
-#define DM_ULOG_REQUEST_VERSION 2
+#define DM_ULOG_REQUEST_VERSION 3
 
 struct dm_ulog_request {
 	/*