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Subject[PATCH 5.8 80/85] scsi: sd: sd_zbc: Fix handling of host-aware ZBC disks
Date
From: Damien Le Moal <damien.lemoal@wdc.com>

commit 27ba3e8ff3ab86449e63d38a8d623053591e65fa upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
block/blk-settings.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
drivers/scsi/sd.c | 30 ++++++++++++++++++------------
drivers/scsi/sd.h | 2 +-
drivers/scsi/sd_zbc.c | 37 ++++++++++++++++++++++---------------
include/linux/blkdev.h | 2 ++
5 files changed, 89 insertions(+), 28 deletions(-)

--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -832,6 +832,52 @@ bool blk_queue_can_use_dma_map_merging(s
}
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;
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2966,26 +2966,32 @@ static void sd_read_block_characteristic

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);
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -260,7 +260,7 @@ static inline blk_status_t sd_zbc_setup_
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,
--- a/drivers/scsi/sd_zbc.c
+++ b/drivers/scsi/sd_zbc.c
@@ -645,9 +645,18 @@ static int sd_zbc_revalidate_zones(struc
unsigned int nr_zones)
{
struct gendisk *disk = sdkp->disk;
+ struct request_queue *q = disk->queue;
+ u32 max_append;
int ret = 0;

/*
+ * There is nothing to do for regular disks, including host-aware disks
+ * that have partitions.
+ */
+ if (!blk_queue_is_zoned(q))
+ return 0;
+
+ /*
* Make sure revalidate zones are serialized to ensure exclusive
* updates of the scsi disk data.
*/
@@ -681,6 +690,19 @@ static int sd_zbc_revalidate_zones(struc
kvfree(sdkp->rev_wp_offset);
sdkp->rev_wp_offset = NULL;

+ if (ret) {
+ sdkp->zone_blocks = 0;
+ sdkp->nr_zones = 0;
+ sdkp->capacity = 0;
+ goto unlock;
+ }
+
+ max_append = min_t(u32, logical_to_sectors(sdkp->device, zone_blocks),
+ q->limits.max_segments << (PAGE_SHIFT - 9));
+ max_append = min_t(u32, max_append, queue_max_hw_sectors(q));
+
+ blk_queue_max_zone_append_sectors(q, max_append);
+
unlock:
mutex_unlock(&sdkp->rev_mutex);

@@ -693,7 +715,6 @@ int sd_zbc_read_zones(struct scsi_disk *
struct request_queue *q = disk->queue;
unsigned int nr_zones;
u32 zone_blocks = 0;
- u32 max_append;
int ret;

if (!sd_is_zoned(sdkp))
@@ -726,20 +747,6 @@ int sd_zbc_read_zones(struct scsi_disk *
if (ret)
goto err;

- /*
- * On the first scan 'chunk_sectors' isn't setup yet, so calling
- * blk_queue_max_zone_append_sectors() will result in a WARN(). Defer
- * this setting to the second scan.
- */
- if (sdkp->first_scan)
- return 0;
-
- max_append = min_t(u32, logical_to_sectors(sdkp->device, zone_blocks),
- q->limits.max_segments << (PAGE_SHIFT - 9));
- max_append = min_t(u32, max_append, queue_max_hw_sectors(q));
-
- blk_queue_max_zone_append_sectors(q, max_append);
-
return 0;

err:
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -354,6 +354,8 @@ 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)

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