block: add a zone condition debug helper

Add a helper to stringify the zone conditions. We use this helper in the
next patch to track zone conditions in tracepoints.
Reviewed-by: NDamien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

block/blk-zoned.c

@@ -20,6 +20,38 @@
 
 #include "blk.h"
 
+#define ZONE_COND_NAME(name) [BLK_ZONE_COND_##name] = #name
+static const char *const zone_cond_name[] = {
+	ZONE_COND_NAME(NOT_WP),
+	ZONE_COND_NAME(EMPTY),
+	ZONE_COND_NAME(IMP_OPEN),
+	ZONE_COND_NAME(EXP_OPEN),
+	ZONE_COND_NAME(CLOSED),
+	ZONE_COND_NAME(READONLY),
+	ZONE_COND_NAME(FULL),
+	ZONE_COND_NAME(OFFLINE),
+};
+#undef ZONE_COND_NAME
+
+/**
+ * blk_zone_cond_str - Return string XXX in BLK_ZONE_COND_XXX.
+ * @zone_cond: BLK_ZONE_COND_XXX.
+ *
+ * Description: Centralize block layer function to convert BLK_ZONE_COND_XXX
+ * into string format. Useful in the debugging and tracing zone conditions. For
+ * invalid BLK_ZONE_COND_XXX it returns string "UNKNOWN".
+ */
+const char *blk_zone_cond_str(enum blk_zone_cond zone_cond)
+{
+	static const char *zone_cond_str = "UNKNOWN";
+
+	if (zone_cond < ARRAY_SIZE(zone_cond_name) && zone_cond_name[zone_cond])
+		zone_cond_str = zone_cond_name[zone_cond];
+
+	return zone_cond_str;
+}
+EXPORT_SYMBOL_GPL(blk_zone_cond_str);
+
 static inline sector_t blk_zone_start(struct request_queue *q,
 				      sector_t sector)
 {

include/linux/blkdev.h

@@ -952,6 +952,10 @@ static inline unsigned int blk_rq_stats_sectors(const struct request *rq)
 }
 
 #ifdef CONFIG_BLK_DEV_ZONED
+
+/* Helper to convert BLK_ZONE_ZONE_XXX to its string format XXX */
+const char *blk_zone_cond_str(enum blk_zone_cond zone_cond);
+
 static inline unsigned int blk_rq_zone_no(struct request *rq)
 {
 	return blk_queue_zone_no(rq->q, blk_rq_pos(rq));