thin: add discard support for thin pool

Add arg support for discard.
Add discard ignore, nopassdown, passdown (=default) support.
Flags could be set per pool.

lvcreate [--discard {ignore|no_passdown|passdown}]  vg/thinlv

2 files changed, 44 insertions, 0 deletions

diff --git a/lib/metadata/metadata-exported.h b/lib/metadata/metadata-exported.h
index 8c655c76..d2afdb1f 100644
--- a/lib/metadata/metadata-exported.h
+++ b/lib/metadata/metadata-exported.h
@@ -166,6 +166,12 @@ typedef enum {
 	DONT_PROMPT_OVERRIDE = 2 /* Skip prompt + override a second condition */
 } force_t;
 
+typedef enum {
+	THIN_DISCARD_PASSDOWN,
+	THIN_DISCARD_NO_PASSDOWN,
+	THIN_DISCARD_IGNORE,
+} thin_discard_t;
+
 struct cmd_context;
 struct format_handler;
 struct labeller;
@@ -347,6 +353,7 @@ struct lv_segment {
 	uint64_t transaction_id;		/* For thin_pool, thin */
 	uint64_t low_water_mark;		/* For thin_pool */
 	unsigned zero_new_blocks;		/* For thin_pool */
+	thin_discard_t discard;			/* For thin_pool */
 	struct dm_list thin_messages;		/* For thin_pool */
 	struct logical_volume *pool_lv;		/* For thin */
 	uint32_t device_id;			/* For thin, 24bit */
@@ -558,6 +565,8 @@ uint64_t extents_from_size(struct cmd_context *cmd, uint64_t size,
 			   uint32_t extent_size);
 
 int update_pool_lv(struct logical_volume *lv, int activate);
+int get_pool_discard(const char *str, thin_discard_t *discard);
+const char *get_pool_discard_name(thin_discard_t discard);
 
 /*
  * Activation options
diff --git a/lib/metadata/thin_manip.c b/lib/metadata/thin_manip.c
index ae8d509e..8d1744cd 100644
--- a/lib/metadata/thin_manip.c
+++ b/lib/metadata/thin_manip.c
@@ -428,3 +428,38 @@ int update_pool_lv(struct logical_volume *lv, int activate)
 
 	return 1;
 }
+
+int get_pool_discard(const char *str, thin_discard_t *discard)
+{
+	if (!strcasecmp(str, "passdown"))
+		*discard = THIN_DISCARD_PASSDOWN;
+        /* Allow some variation in thin parameter */
+	else if (!strcasecmp(str, "nopassdown") ||
+		 !strcasecmp(str, "no-passdown") ||
+		 !strcasecmp(str, "no_passdown"))
+		*discard = THIN_DISCARD_NO_PASSDOWN;
+	else if (!strcasecmp(str, "ignore"))
+		*discard = THIN_DISCARD_IGNORE;
+	else {
+		log_error("Thin pool discard type %s is unknown.", str);
+		return 0;
+	}
+
+	return 1;
+}
+
+const char *get_pool_discard_name(thin_discard_t discard)
+{
+	switch (discard) {
+	case THIN_DISCARD_PASSDOWN:
+                return "passdown";
+	case THIN_DISCARD_NO_PASSDOWN:
+		return "nopassdown";
+	case THIN_DISCARD_IGNORE:
+		return "ignore";
+	}
+
+	log_error(INTERNAL_ERROR "Uknown discard type.");
+
+	return NULL;
+}