scsi: sd: sd_zbc: Fix handling of host-aware ZBC disks

When CONFIG_BLK_DEV_ZONED is disabled, allow using host-aware ZBC disks as
regular disks. In this case, ensure that command completion is correctly
executed by changing sd_zbc_complete() to return good_bytes instead of 0
and causing a hang during device probe (endless retries).

When CONFIG_BLK_DEV_ZONED is enabled and a host-aware disk is detected to
have partitions, it will be used as a regular disk. In this case, make sure
to not do anything in sd_zbc_revalidate_zones() as that triggers warnings.

Since all these different cases result in subtle settings of the disk queue
zoned model, introduce the block layer helper function
blk_queue_set_zoned() to generically implement setting up the effective
zoned model according to the disk type, the presence of partitions on the
disk and CONFIG_BLK_DEV_ZONED configuration.

Link: https://lore.kernel.org/r/20200915073347.832424-2-damien.lemoal@wdc.com
Fixes: b72053072c0b ("block: allow partitions on host aware zone devices")
Cc: <stable@vger.kernel.org>
Reported-by: Borislav Petkov <bp@alien8.de>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 76a7e03bcd6c..34b721a2743a 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -801,6 +801,52 @@ bool blk_queue_can_use_dma_map_merging(struct request_queue *q,
 }
 EXPORT_SYMBOL_GPL(blk_queue_can_use_dma_map_merging);
 
+/**
+ * blk_queue_set_zoned - configure a disk queue zoned model.
+ * @disk:	the gendisk of the queue to configure
+ * @model:	the zoned model to set
+ *
+ * Set the zoned model of the request queue of @disk according to @model.
+ * When @model is BLK_ZONED_HM (host managed), this should be called only
+ * if zoned block device support is enabled (CONFIG_BLK_DEV_ZONED option).
+ * If @model specifies BLK_ZONED_HA (host aware), the effective model used
+ * depends on CONFIG_BLK_DEV_ZONED settings and on the existence of partitions
+ * on the disk.
+ */
+void blk_queue_set_zoned(struct gendisk *disk, enum blk_zoned_model model)
+{
+	switch (model) {
+	case BLK_ZONED_HM:
+		/*
+		 * Host managed devices are supported only if
+		 * CONFIG_BLK_DEV_ZONED is enabled.
+		 */
+		WARN_ON_ONCE(!IS_ENABLED(CONFIG_BLK_DEV_ZONED));
+		break;
+	case BLK_ZONED_HA:
+		/*
+		 * Host aware devices can be treated either as regular block
+		 * devices (similar to drive managed devices) or as zoned block
+		 * devices to take advantage of the zone command set, similarly
+		 * to host managed devices. We try the latter if there are no
+		 * partitions and zoned block device support is enabled, else
+		 * we do nothing special as far as the block layer is concerned.
+		 */
+		if (!IS_ENABLED(CONFIG_BLK_DEV_ZONED) ||
+		    disk_has_partitions(disk))
+			model = BLK_ZONED_NONE;
+		break;
+	case BLK_ZONED_NONE:
+	default:
+		if (WARN_ON_ONCE(model != BLK_ZONED_NONE))
+			model = BLK_ZONED_NONE;
+		break;
+	}
+
+	disk->queue->limits.zoned = model;
+}
+EXPORT_SYMBOL_GPL(blk_queue_set_zoned);
+
 static int __init blk_settings_init(void)
 {
 	blk_max_low_pfn = max_low_pfn - 1;