writecache: report status fields

reporting fields (-o) directly from kernel:
writecache_total_blocks
writecache_free_blocks
writecache_writeback_blocks
writecache_error

The data_percent field shows used cache blocks / total cache blocks.

device_mapper/all.h

@@ -383,7 +383,7 @@ int dm_get_status_cache(struct dm_pool *mem, const char *params,
 			struct dm_status_cache **status);
 
 struct dm_status_writecache {
-	uint32_t error;
+	uint64_t error;
 	uint64_t total_blocks;
 	uint64_t free_blocks;
 	uint64_t writeback_blocks;

device_mapper/libdm-targets.c

@@ -366,8 +366,8 @@ int dm_get_status_writecache(struct dm_pool *mem, const char *params,
 	if (!(s = dm_pool_zalloc(mem, sizeof(struct dm_status_writecache))))
 		return_0;
 
-	if (sscanf(params, "%u %llu %llu %llu",
+	if (sscanf(params, "%llu %llu %llu %llu",
-		   &s->error,
+		   (unsigned long long *)&s->error,
 		   (unsigned long long *)&s->total_blocks,
 		   (unsigned long long *)&s->free_blocks,
 		   (unsigned long long *)&s->writeback_blocks) != 4) {

lib/metadata/lv.c

@@ -405,6 +405,14 @@ dm_percent_t lvseg_percent_with_info_and_seg_status(const struct lv_with_info_an
 			}
 		}
 		break;
+	case SEG_STATUS_WRITECACHE:
+		if (type != PERCENT_GET_DATA)
+			p = DM_PERCENT_INVALID;
+		else {
+			uint64_t used = s->writecache->total_blocks - s->writecache->free_blocks;
+			p = dm_make_percent(used, s->writecache->total_blocks);
+		}
+		break;
 	case SEG_STATUS_RAID:
 		switch (type) {
 		case PERCENT_GET_DIRTY:

lib/report/columns.h

@@ -151,6 +151,10 @@ FIELD(LVSSTATUS, lv, STR, "VDOCompressionState", lvid, 0, vdo_compression_state,
 FIELD(LVSSTATUS, lv, STR, "VDOIndexState", lvid, 0, vdo_index_state, vdo_index_state, "For vdo pools, state of index for deduplication.", 0)
 FIELD(LVSSTATUS, lv, NUM, "VDOUsedSize", lvid, 0, vdo_used_size, vdo_used_size, "For vdo pools, currently used space.", 0)
 FIELD(LVSSTATUS, lv, NUM, "VDOSaving%", lvid, 0, vdo_saving_percent, vdo_saving_percent, "For vdo pools, percentage of saved space.", 0)
+FIELD(LVSSTATUS, lv, NUM, "WCacheTotalBlocks", lvid, 0, writecache_total_blocks, writecache_total_blocks, "Total writecache blocks.", 0)
+FIELD(LVSSTATUS, lv, NUM, "WCacheFreeBlocks", lvid, 0, writecache_free_blocks, writecache_free_blocks, "Total writecache free blocks.", 0)
+FIELD(LVSSTATUS, lv, NUM, "WCacheWritebackBlocks", lvid, 0, writecache_writeback_blocks, writecache_writeback_blocks, "Total writecache writeback blocks.", 0)
+FIELD(LVSSTATUS, lv, NUM, "WCacheErrors", lvid, 0, writecache_error, writecache_error, "Total writecache errors.", 0)
 /*
  * End of LVSSTATUS type fields
  */

lib/report/properties.c

@@ -279,6 +279,15 @@ GET_PV_NUM_PROPERTY_FN(pv_ba_size, SECTOR_SIZE * pv->ba_size)
 #define _cache_write_misses_set prop_not_implemented_set
 #define _cache_write_misses_get prop_not_implemented_get
 
+#define _writecache_total_blocks_set prop_not_implemented_set
+#define _writecache_total_blocks_get prop_not_implemented_get
+#define _writecache_free_blocks_set prop_not_implemented_set
+#define _writecache_free_blocks_get prop_not_implemented_get
+#define _writecache_writeback_blocks_set prop_not_implemented_set
+#define _writecache_writeback_blocks_get prop_not_implemented_get
+#define _writecache_error_set prop_not_implemented_set
+#define _writecache_error_get prop_not_implemented_get
+
 #define _vdo_operating_mode_set prop_not_implemented_set
 #define _vdo_operating_mode_get prop_not_implemented_get
 #define _vdo_compression_state_set prop_not_implemented_set

lib/report/report.c

@@ -3875,6 +3875,27 @@ GENERATE_CACHE_STATUS_DISP_FN(read_misses)
 GENERATE_CACHE_STATUS_DISP_FN(write_hits)
 GENERATE_CACHE_STATUS_DISP_FN(write_misses)
 
+/*
+ * Macro to generate '_writecache_<cache_status_field_name>_disp' reporting function.
+ * The 'writecache_status_field_name' is field name from struct dm_writecache_status.
+ */
+#define GENERATE_WRITECACHE_STATUS_DISP_FN(writecache_status_field_name) \
+static int _writecache_ ## writecache_status_field_name ## _disp (struct dm_report *rh, \
+							struct dm_pool *mem, \
+							struct dm_report_field *field, \
+							const void *data, \
+							void *private) \
+{ \
+	const struct lv_with_info_and_seg_status *lvdm = (const struct lv_with_info_and_seg_status *) data; \
+	if (lvdm->seg_status.type != SEG_STATUS_WRITECACHE) \
+		return _field_set_value(field, "", &GET_TYPE_RESERVED_VALUE(num_undef_64)); \
+	return dm_report_field_uint64(rh, field, &lvdm->seg_status.writecache->writecache_status_field_name); \
+}
+
+GENERATE_WRITECACHE_STATUS_DISP_FN(total_blocks)
+GENERATE_WRITECACHE_STATUS_DISP_FN(free_blocks)
+GENERATE_WRITECACHE_STATUS_DISP_FN(writeback_blocks)
+GENERATE_WRITECACHE_STATUS_DISP_FN(error)
 
 /*
  * Macro to generate '_vdo_<vdo_field_name>_disp' reporting function.