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>

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 76a7e03..34b721a 100644 (file)
--- 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;

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 95018e6..06286b6 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2964,26 +2964,32 @@ static void sd_read_block_characteristics(struct scsi_disk *sdkp)
 
        if (sdkp->device->type == TYPE_ZBC) {
                /* Host-managed */
-               q->limits.zoned = BLK_ZONED_HM;
+               blk_queue_set_zoned(sdkp->disk, BLK_ZONED_HM);
        } else {
                sdkp->zoned = (buffer[8] >> 4) & 3;
-               if (sdkp->zoned == 1 && !disk_has_partitions(sdkp->disk)) {
+               if (sdkp->zoned == 1) {
                        /* Host-aware */
-                       q->limits.zoned = BLK_ZONED_HA;
+                       blk_queue_set_zoned(sdkp->disk, BLK_ZONED_HA);
                } else {
-                       /*
-                        * Treat drive-managed devices and host-aware devices
-                        * with partitions as regular block devices.
-                        */
-                       q->limits.zoned = BLK_ZONED_NONE;
-                       if (sdkp->zoned == 2 && sdkp->first_scan)
-                               sd_printk(KERN_NOTICE, sdkp,
-                                         "Drive-managed SMR disk\n");
+                       /* Regular disk or drive managed disk */
+                       blk_queue_set_zoned(sdkp->disk, BLK_ZONED_NONE);
                }
        }
-       if (blk_queue_is_zoned(q) && sdkp->first_scan)
+
+       if (!sdkp->first_scan)
+               goto out;
+
+       if (blk_queue_is_zoned(q)) {
                sd_printk(KERN_NOTICE, sdkp, "Host-%s zoned block device\n",
                      q->limits.zoned == BLK_ZONED_HM ? "managed" : "aware");
+       } else {
+               if (sdkp->zoned == 1)
+                       sd_printk(KERN_NOTICE, sdkp,
+                                 "Host-aware SMR disk used as regular disk\n");
+               else if (sdkp->zoned == 2)
+                       sd_printk(KERN_NOTICE, sdkp,
+                                 "Drive-managed SMR disk\n");
+       }
 
  out:
        kfree(buffer);

diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 4933e7d..7251434 100644 (file)
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -259,7 +259,7 @@ static inline blk_status_t sd_zbc_setup_zone_mgmt_cmnd(struct scsi_cmnd *cmd,
 static inline unsigned int sd_zbc_complete(struct scsi_cmnd *cmd,
                        unsigned int good_bytes, struct scsi_sense_hdr *sshdr)
 {
-       return 0;
+       return good_bytes;
 }
 
 static inline blk_status_t sd_zbc_prepare_zone_append(struct scsi_cmnd *cmd,

diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
index 0e94ff0..a739456 100644 (file)
--- a/drivers/scsi/sd_zbc.c
+++ b/drivers/scsi/sd_zbc.c
@@ -667,7 +667,11 @@ int sd_zbc_revalidate_zones(struct scsi_disk *sdkp)
        u32 max_append;
        int ret = 0;
 
-       if (!sd_is_zoned(sdkp))
+       /*
+        * There is nothing to do for regular disks, including host-aware disks
+        * that have partitions.
+        */
+       if (!blk_queue_is_zoned(q))
                return 0;
 
        /*

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index bb5636c..868e11f 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -352,6 +352,8 @@ struct queue_limits {
 typedef int (*report_zones_cb)(struct blk_zone *zone, unsigned int idx,
                               void *data);
 
+void blk_queue_set_zoned(struct gendisk *disk, enum blk_zoned_model model);
+
 #ifdef CONFIG_BLK_DEV_ZONED
 
 #define BLK_ALL_ZONES  ((unsigned int)-1)