block: Replace zone_wlock debugfs entry with zone_wplugs entry

In preparation to completely remove zone write locking, replace the
"zone_wlock" mq-debugfs entry that was listing zones that are
write-locked with the zone_wplugs entry which lists the zones that
currently have a write plug allocated.

The write plug information provided is: the zone number, the zone write
plug flags, the zone write plug write pointer offset and the number of
BIOs currently waiting for execution in the zone write plug BIO list.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240408014128.205141-26-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: damien-lemoal

block/blk-mq-debugfs.c

@@ -160,7 +160,7 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = {
 	{ "requeue_list", 0400, .seq_ops = &queue_requeue_list_seq_ops },
 	{ "pm_only", 0600, queue_pm_only_show, NULL },
 	{ "state", 0600, queue_state_show, queue_state_write },
-	{ "zone_wlock", 0400, queue_zone_wlock_show, NULL },
+	{ "zone_wplugs", 0400, queue_zone_wplugs_show, NULL },
 	{ },
 };
 

block/blk-mq-debugfs.h

@@ -84,9 +84,9 @@ static inline void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos)
 #endif
 
 #if defined(CONFIG_BLK_DEV_ZONED) && defined(CONFIG_BLK_DEBUG_FS)
-int queue_zone_wlock_show(void *data, struct seq_file *m);
+int queue_zone_wplugs_show(void *data, struct seq_file *m);
 #else
-static inline int queue_zone_wlock_show(void *data, struct seq_file *m)
+static inline int queue_zone_wplugs_show(void *data, struct seq_file *m)
 {
 	return 0;
 }

block/blk-zoned.c

@@ -1808,17 +1808,34 @@ EXPORT_SYMBOL_GPL(blk_revalidate_disk_zones);
 
 #ifdef CONFIG_BLK_DEBUG_FS
 
-int queue_zone_wlock_show(void *data, struct seq_file *m)
+int queue_zone_wplugs_show(void *data, struct seq_file *m)
 {
 	struct request_queue *q = data;
-	unsigned int i;
+	struct gendisk *disk = q->disk;
+	struct blk_zone_wplug *zwplug;
+	unsigned int zwp_wp_offset, zwp_flags;
+	unsigned int zwp_zone_no, zwp_ref;
+	unsigned int zwp_bio_list_size, i;
+	unsigned long flags;
 
-	if (!q->disk->seq_zones_wlock)
-		return 0;
+	rcu_read_lock();
+	for (i = 0; i < disk_zone_wplugs_hash_size(disk); i++) {
+		hlist_for_each_entry_rcu(zwplug,
+					 &disk->zone_wplugs_hash[i], node) {
+			spin_lock_irqsave(&zwplug->lock, flags);
+			zwp_zone_no = zwplug->zone_no;
+			zwp_flags = zwplug->flags;
+			zwp_ref = atomic_read(&zwplug->ref);
+			zwp_wp_offset = zwplug->wp_offset;
+			zwp_bio_list_size = bio_list_size(&zwplug->bio_list);
+			spin_unlock_irqrestore(&zwplug->lock, flags);
 
-	for (i = 0; i < q->disk->nr_zones; i++)
-		if (test_bit(i, q->disk->seq_zones_wlock))
-			seq_printf(m, "%u\n", i);
+			seq_printf(m, "%u 0x%x %u %u %u\n",
+				   zwp_zone_no, zwp_flags, zwp_ref,
+				   zwp_wp_offset, zwp_bio_list_size);
+		}
+	}
+	rcu_read_unlock();
 
 	return 0;
 }