block: Introduce blk_revalidate_disk_zones()

Drivers exposing zoned block devices have to initialize and maintain
correctness (i.e. revalidate) of the device zone bitmaps attached to
the device request queue (seq_zones_bitmap and seq_zones_wlock).

To simplify coding this, introduce a generic helper function
blk_revalidate_disk_zones() suitable for most (and likely all) cases.
This new function always update the seq_zones_bitmap and seq_zones_wlock
bitmaps as well as the queue nr_zones field when called for a disk
using a request based queue. For a disk using a BIO based queue, only
the number of zones is updated since these queues do not have
schedulers and so do not need the zone bitmaps.

With this change, the zone bitmap initialization code in sd_zbc.c can be
replaced with a call to this function in sd_zbc_read_zones(), which is
called from the disk revalidate block operation method.

A call to blk_revalidate_disk_zones() is also added to the null_blk
driver for devices created with the zoned mode enabled.

Finally, to ensure that zoned devices created with dm-linear or
dm-flakey expose the correct number of zones through sysfs, a call to
blk_revalidate_disk_zones() is added to dm_table_set_restrictions().

The zone bitmaps allocated and initialized with
blk_revalidate_disk_zones() are freed automatically from
__blk_release_queue() using the block internal function
blk_queue_free_zone_bitmaps().

Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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>

1 files changed, 6 insertions, 0 deletions

diff --git a/block/blk.h b/block/blk.h
index 93574baaa6b8..a1841b8ff129 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -490,4 +490,10 @@ static inline int blk_iolatency_init(struct request_queue *q) { return 0; }
 
 struct bio *blk_next_bio(struct bio *bio, unsigned int nr_pages, gfp_t gfp);
 
+#ifdef CONFIG_BLK_DEV_ZONED
+void blk_queue_free_zone_bitmaps(struct request_queue *q);
+#else
+static inline void blk_queue_free_zone_bitmaps(struct request_queue *q) {}
+#endif
+
 #endif /* BLK_INTERNAL_H */