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-rw-r--r--include/uapi/linux/dm-log-userspace.h20
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 {
/*