block: add a report_zones method

Dispatching a report zones command through the request queue is a major
pain due to the command reply payload rewriting necessary. Given that
blkdev_report_zones() is executing everything synchronously, implement
report zones as a block device file operation instead, allowing major
simplification of the code in many places.

sd, null-blk, dm-linear and dm-flakey being the only block device
drivers supporting exposing zoned block devices, these drivers are
modified to provide the device side implementation of the
report_zones() block device file operation.

For device mappers, a new report_zones() target type operation is
defined so that the upper block layer calls blkdev_report_zones() can
be propagated down to the underlying devices of the dm targets.
Implementation for this new operation is added to the dm-linear and
dm-flakey targets.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
[Damien]
* Changed method block_device argument to gendisk
* Various bug fixes and improvements
* Added support for null_blk, dm-linear and dm-flakey.
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 13 insertions, 9 deletions

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 9578c7ab1eb6..093a818c5b68 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -283,8 +283,6 @@ enum req_opf {
 	REQ_OP_FLUSH		= 2,
 	/* discard sectors */
 	REQ_OP_DISCARD		= 3,
-	/* get zone information */
-	REQ_OP_ZONE_REPORT	= 4,
 	/* securely erase sectors */
 	REQ_OP_SECURE_ERASE	= 5,
 	/* seset a zone write pointer */
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6bb845f9601a..51fe6472ce02 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -396,11 +396,6 @@ struct queue_limits {
 
 #ifdef CONFIG_BLK_DEV_ZONED
 
-struct blk_zone_report_hdr {
-	unsigned int	nr_zones;
-	u8		padding[60];
-};
-
 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,
@@ -1867,6 +1862,9 @@ struct block_device_operations {
 	int (*getgeo)(struct block_device *, struct hd_geometry *);
 	/* 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,
+			    gfp_t gfp_mask);
 	struct module *owner;
 	const struct pr_ops *pr_ops;
 };
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 6fb0808e87c8..a23b396a8edc 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -92,6 +92,11 @@ 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,
+				   gfp_t gfp_mask);
+
 /*
  * These iteration functions are typically used to check (and combine)
  * properties of underlying devices.
@@ -180,6 +185,9 @@ struct target_type {
 	dm_status_fn status;
 	dm_message_fn message;
 	dm_prepare_ioctl_fn prepare_ioctl;
+#ifdef CONFIG_BLK_DEV_ZONED
+	dm_report_zones_fn report_zones;
+#endif
 	dm_busy_fn busy;
 	dm_iterate_devices_fn iterate_devices;
 	dm_io_hints_fn io_hints;
@@ -420,8 +428,8 @@ 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, struct bio *bio,
-			  sector_t start);
+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);
 
 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);