block: add capacity field to zone descriptors

In the zoned storage model, the sectors within a zone are typically all
writeable. With the introduction of the Zoned Namespace (ZNS) Command
Set in the NVM Express organization, the model was extended to have a
specific writeable capacity.

Extend the zone descriptor data structure with a zone capacity field to
indicate to the user how many sectors in a zone are writeable.

Introduce backward compatibility in the zone report ioctl by extending
the zone report header data structure with a flags field to indicate if
the capacity field is available.

Reviewed-by: Jens Axboe <[email protected]>
Reviewed-by: Javier González <[email protected]>
Reviewed-by: Chaitanya Kulkarni <[email protected]>
Reviewed-by: Himanshu Madhani <[email protected]>
Reviewed-by: Martin K. Petersen <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Reviewed-by: Daniel Wagner <[email protected]>
Signed-off-by: Matias Bjørling <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>

1 files changed, 13 insertions, 2 deletions

diff --git a/include/uapi/linux/blkzoned.h b/include/uapi/linux/blkzoned.h
index 0cdef67135f0..42c3366cc25f 100644
--- a/include/uapi/linux/blkzoned.h
+++ b/include/uapi/linux/blkzoned.h
@@ -74,6 +74,15 @@ enum blk_zone_cond {
 };
 
 /**
+ * enum blk_zone_report_flags - Feature flags of reported zone descriptors.
+ *
+ * @BLK_ZONE_REP_CAPACITY: Zone descriptor has capacity field.
+ */
+enum blk_zone_report_flags {
+	BLK_ZONE_REP_CAPACITY	= (1 << 0),
+};
+
+/**
  * struct blk_zone - Zone descriptor for BLKREPORTZONE ioctl.
  *
  * @start: Zone start in 512 B sector units
@@ -99,7 +108,9 @@ struct blk_zone {
 	__u8	cond;		/* Zone condition */
 	__u8	non_seq;	/* Non-sequential write resources active */
 	__u8	reset;		/* Reset write pointer recommended */
-	__u8	reserved[36];
+	__u8	resv[4];
+	__u64	capacity;	/* Zone capacity in number of sectors */
+	__u8	reserved[24];
 };
 
 /**
@@ -115,7 +126,7 @@ struct blk_zone {
 struct blk_zone_report {
 	__u64		sector;
 	__u32		nr_zones;
-	__u8		reserved[4];
+	__u32		flags;
 	struct blk_zone zones[0];
 };