block: rework zone reporting

Avoid the need to allocate a potentially large array of struct blk_zone
in the block layer by switching the ->report_zones method interface to
a callback model. Now the caller simply supplies a callback that is
executed on each reported zone, and private data for it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 26 insertions, 13 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6a4f7abbdcf7..397bb9bc230b 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -349,17 +349,16 @@ struct queue_limits {
 	enum blk_zoned_model	zoned;
 };
 
+typedef int (*report_zones_cb)(struct blk_zone *zone, unsigned int idx,
+			       void *data);
+
 #ifdef CONFIG_BLK_DEV_ZONED
 
-/*
- * Maximum number of zones to report with a single report zones command.
- */
-#define BLK_ZONED_REPORT_MAX_ZONES	8192U
+#define BLK_ALL_ZONES  ((unsigned int)-1)
+int blkdev_report_zones(struct block_device *bdev, sector_t sector,
+			unsigned int nr_zones, report_zones_cb cb, void *data);
 
 extern unsigned int blkdev_nr_zones(struct block_device *bdev);
-extern int blkdev_report_zones(struct block_device *bdev,
-			       sector_t sector, struct blk_zone *zones,
-			       unsigned int *nr_zones);
 extern int blkdev_zone_mgmt(struct block_device *bdev, enum req_opf op,
 			    sector_t sectors, sector_t nr_sectors,
 			    gfp_t gfp_mask);
@@ -1709,7 +1708,7 @@ struct block_device_operations {
 	/* this callback is with swap_lock and sometimes page table lock held */
 	void (*swap_slot_free_notify) (struct block_device *, unsigned long);
 	int (*report_zones)(struct gendisk *, sector_t sector,
-			    struct blk_zone *zones, unsigned int *nr_zones);
+			unsigned int nr_zones, report_zones_cb cb, void *data);
 	struct module *owner;
 	const struct pr_ops *pr_ops;
 };
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 399ad8632356..a164cc81b710 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -17,6 +17,7 @@
 struct dm_dev;
 struct dm_target;
 struct dm_table;
+struct dm_report_zones_args;
 struct mapped_device;
 struct bio_vec;
 
@@ -93,9 +94,9 @@ typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv,
 
 typedef int (*dm_prepare_ioctl_fn) (struct dm_target *ti, struct block_device **bdev);
 
-typedef int (*dm_report_zones_fn) (struct dm_target *ti, sector_t sector,
-				   struct blk_zone *zones,
-				   unsigned int *nr_zones);
+typedef int (*dm_report_zones_fn) (struct dm_target *ti,
+				   struct dm_report_zones_args *args,
+				   unsigned int nr_zones);
 
 /*
  * These iteration functions are typically used to check (and combine)
@@ -422,10 +423,23 @@ struct gendisk *dm_disk(struct mapped_device *md);
 int dm_suspended(struct dm_target *ti);
 int dm_noflush_suspending(struct dm_target *ti);
 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
-void dm_remap_zone_report(struct dm_target *ti, sector_t start,
-			  struct blk_zone *zones, unsigned int *nr_zones);
 union map_info *dm_get_rq_mapinfo(struct request *rq);
 
+#ifdef CONFIG_BLK_DEV_ZONED
+struct dm_report_zones_args {
+	struct dm_target *tgt;
+	sector_t next_sector;
+
+	void *orig_data;
+	report_zones_cb orig_cb;
+	unsigned int zone_idx;
+
+	/* must be filled by ->report_zones before calling dm_report_zones_cb */
+	sector_t start;
+};
+int dm_report_zones_cb(struct blk_zone *zone, unsigned int idx, void *data);
+#endif /* CONFIG_BLK_DEV_ZONED */
+
 /*
  * Device mapper functions to parse and create devices specified by the
  * parameter "dm-mod.create="