block: remove support for the host aware zone model

When zones were first added the SCSI and ATA specs, two different
models were supported (in addition to the drive managed one that
is invisible to the host):

 - host managed where non-conventional zones there is strict requirement
   to write at the write pointer, or else an error is returned
 - host aware where a write point is maintained if writes always happen
   at it, otherwise it is left in an under-defined state and the
   sequential write preferred zones behave like conventional zones
   (probably very badly performing ones, though)

Not surprisingly this lukewarm model didn't prove to be very useful and
was finally removed from the ZBC and SBC specs (NVMe never implemented
it).  Due to to the easily disappearing write pointer host software
could never rely on the write pointer to actually be useful for say
recovery.

Fortunately only a few HDD prototypes shipped using this model which
never made it to mass production.  Drop the support before it is too
late.  Note that any such host aware prototype HDD can still be used
with Linux as we'll now treat it as a conventional HDD.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20231217165359.604246-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 3 insertions, 34 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 185ed3770e3a..28cda9fb239e 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -264,18 +264,6 @@ static inline bool blk_op_is_passthrough(blk_opf_t op)
 }
 
 /*
- * Zoned block device models (zoned limit).
- *
- * Note: This needs to be ordered from the least to the most severe
- * restrictions for the inheritance in blk_stack_limits() to work.
- */
-enum blk_zoned_model {
-	BLK_ZONED_NONE = 0,	/* Regular block device */
-	BLK_ZONED_HA,		/* Host-aware zoned block device */
-	BLK_ZONED_HM,		/* Host-managed zoned block device */
-};
-
-/*
  * BLK_BOUNCE_NONE:	never bounce (default)
  * BLK_BOUNCE_HIGH:	bounce all highmem pages
  */
@@ -316,7 +304,7 @@ struct queue_limits {
 	unsigned char		misaligned;
 	unsigned char		discard_misaligned;
 	unsigned char		raid_partial_stripes_expensive;
-	enum blk_zoned_model	zoned;
+	bool			zoned;
 
 	/*
 	 * Drivers that set dma_alignment to less than 511 must be prepared to
@@ -329,7 +317,7 @@ struct queue_limits {
 typedef int (*report_zones_cb)(struct blk_zone *zone, unsigned int idx,
 			       void *data);
 
-void disk_set_zoned(struct gendisk *disk, enum blk_zoned_model model);
+void disk_set_zoned(struct gendisk *disk, bool zoned);
 
 #define BLK_ALL_ZONES  ((unsigned int)-1)
 int blkdev_report_zones(struct block_device *bdev, sector_t sector,
@@ -617,23 +605,9 @@ static inline enum rpm_status queue_rpm_status(struct request_queue *q)
 }
 #endif
 
-static inline enum blk_zoned_model
-blk_queue_zoned_model(struct request_queue *q)
-{
-	if (IS_ENABLED(CONFIG_BLK_DEV_ZONED))
-		return q->limits.zoned;
-	return BLK_ZONED_NONE;
-}
-
 static inline bool blk_queue_is_zoned(struct request_queue *q)
 {
-	switch (blk_queue_zoned_model(q)) {
-	case BLK_ZONED_HA:
-	case BLK_ZONED_HM:
-		return true;
-	default:
-		return false;
-	}
+	return IS_ENABLED(CONFIG_BLK_DEV_ZONED) && q->limits.zoned;
 }
 
 #ifdef CONFIG_BLK_DEV_ZONED
@@ -1260,11 +1234,6 @@ static inline bool bdev_nowait(struct block_device *bdev)
 	return test_bit(QUEUE_FLAG_NOWAIT, &bdev_get_queue(bdev)->queue_flags);
 }
 
-static inline enum blk_zoned_model bdev_zoned_model(struct block_device *bdev)
-{
-	return blk_queue_zoned_model(bdev_get_queue(bdev));
-}
-
 static inline bool bdev_is_zoned(struct block_device *bdev)
 {
 	return blk_queue_is_zoned(bdev_get_queue(bdev));