@@ -273,4 +273,11 @@ devices are described in the ZBC (Zoned Block Commands) and ZAC
do not support zone commands, they will be treated as regular block devices
and zoned will report "none".
+zone_write_granularity (RO)
+---------------------------
+This indicates the alignment constraint, in bytes, for write operations in
+sequential zones of zoned block devices (devices with a zoned attributed
+that reports "host-managed" or "host-aware"). This value is always 0 for
+regular block devices.
+
Jens Axboe <jens.axboe@oracle.com>, February 2009
@@ -60,6 +60,7 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->io_opt = 0;
lim->misaligned = 0;
lim->zoned = BLK_ZONED_NONE;
+ lim->zone_write_granularity = 0;
}
EXPORT_SYMBOL(blk_set_default_limits);
@@ -366,6 +367,31 @@ void blk_queue_physical_block_size(struct request_queue *q, unsigned int size)
}
EXPORT_SYMBOL(blk_queue_physical_block_size);
+/**
+ * blk_queue_zone_write_granularity - set zone write granularity for the queue
+ * @q: the request queue for the zoned device
+ * @size: the zone write granularity size, in bytes
+ *
+ * Description:
+ * This should be set to the lowest possible size allowing to write in
+ * sequential zones of a zoned block device.
+ */
+void blk_queue_zone_write_granularity(struct request_queue *q,
+ unsigned int size)
+{
+ if (WARN_ON(!blk_queue_is_zoned(q)))
+ return;
+
+ q->limits.zone_write_granularity = size;
+
+ if (q->limits.zone_write_granularity < q->limits.logical_block_size)
+ q->limits.zone_write_granularity = q->limits.logical_block_size;
+
+ if (q->limits.zone_write_granularity < q->limits.io_min)
+ q->limits.zone_write_granularity = q->limits.io_min;
+}
+EXPORT_SYMBOL_GPL(blk_queue_zone_write_granularity);
+
/**
* blk_queue_alignment_offset - set physical block alignment offset
* @q: the request queue for the device
@@ -631,6 +657,8 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
t->discard_granularity;
}
+ t->zone_write_granularity = max(t->zone_write_granularity,
+ b->zone_write_granularity);
t->zoned = max(t->zoned, b->zoned);
return ret;
}
@@ -219,6 +219,11 @@ static ssize_t queue_write_zeroes_max_show(struct request_queue *q, char *page)
(unsigned long long)q->limits.max_write_zeroes_sectors << 9);
}
+static ssize_t queue_zone_write_granularity_show(struct request_queue *q, char *page)
+{
+ return queue_var_show(q->limits.zone_write_granularity, page);
+}
+
static ssize_t queue_zone_append_max_show(struct request_queue *q, char *page)
{
unsigned long long max_sectors = q->limits.max_zone_append_sectors;
@@ -585,6 +590,7 @@ QUEUE_RO_ENTRY(queue_discard_zeroes_data, "discard_zeroes_data");
QUEUE_RO_ENTRY(queue_write_same_max, "write_same_max_bytes");
QUEUE_RO_ENTRY(queue_write_zeroes_max, "write_zeroes_max_bytes");
QUEUE_RO_ENTRY(queue_zone_append_max, "zone_append_max_bytes");
+QUEUE_RO_ENTRY(queue_zone_write_granularity, "zone_write_granularity");
QUEUE_RO_ENTRY(queue_zoned, "zoned");
QUEUE_RO_ENTRY(queue_nr_zones, "nr_zones");
@@ -639,6 +645,7 @@ static struct attribute *queue_attrs[] = {
&queue_write_same_max_entry.attr,
&queue_write_zeroes_max_entry.attr,
&queue_zone_append_max_entry.attr,
+ &queue_zone_write_granularity_entry.attr,
&queue_nonrot_entry.attr,
&queue_zoned_entry.attr,
&queue_nr_zones_entry.attr,
@@ -113,6 +113,7 @@ int nvme_update_zone_info(struct nvme_ns *ns, unsigned lbaf)
blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
blk_queue_max_open_zones(q, le32_to_cpu(id->mor) + 1);
blk_queue_max_active_zones(q, le32_to_cpu(id->mar) + 1);
+ blk_queue_zone_write_granularity(q, q->limits.logical_block_size);
free_data:
kfree(id);
return status;
@@ -789,6 +789,16 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buf)
blk_queue_max_active_zones(q, 0);
nr_zones = round_up(sdkp->capacity, zone_blocks) >> ilog2(zone_blocks);
+ /*
+ * Per ZBC and ZAC specifications, writes in sequential write required
+ * zones of host-managed devices must be aligned to the device physical
+ * block size.
+ */
+ if (blk_queue_zoned_model(q) == BLK_ZONED_HM)
+ blk_queue_zone_write_granularity(q, sdkp->physical_block_size);
+ else
+ blk_queue_zone_write_granularity(q, sdkp->device->sector_size);
+
/* READ16/WRITE16 is mandatory for ZBC disks */
sdkp->device->use_16_for_rw = 1;
sdkp->device->use_10_for_rw = 0;
@@ -337,6 +337,7 @@ struct queue_limits {
unsigned int max_zone_append_sectors;
unsigned int discard_granularity;
unsigned int discard_alignment;
+ unsigned int zone_write_granularity;
unsigned short max_segments;
unsigned short max_integrity_segments;
@@ -1161,6 +1162,8 @@ extern void blk_queue_logical_block_size(struct request_queue *, unsigned int);
extern void blk_queue_max_zone_append_sectors(struct request_queue *q,
unsigned int max_zone_append_sectors);
extern void blk_queue_physical_block_size(struct request_queue *, unsigned int);
+void blk_queue_zone_write_granularity(struct request_queue *q,
+ unsigned int size);
extern void blk_queue_alignment_offset(struct request_queue *q,
unsigned int alignment);
void blk_queue_update_readahead(struct request_queue *q);
Per ZBC and ZAC specifications, host-managed SMR hard-disks mandate that all writes into sequential write required zones be aligned to the device physical block size. However, NVMe ZNS does not have this constraint and allows write operations into sequential zones to be logical block size aligned. This inconsistency does not help with portability of software across device types. To solve this, introduce the zone_write_granularity queue limit to indicate the alignment constraint, in bytes, of write operations into zones of a zoned block device. This new limit is exported as a read-only sysfs queue attribute and the helper blk_queue_zone_write_granularity() introduced for drivers to set this limit. The scsi disk driver is modified to use this helper to set host-managed SMR disk zone write granularity to the disk physical block size. The nvme driver zns support use this helper to set the new limit to the logical block size of the zoned namespace. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> --- Documentation/block/queue-sysfs.rst | 7 +++++++ block/blk-settings.c | 28 ++++++++++++++++++++++++++++ block/blk-sysfs.c | 7 +++++++ drivers/nvme/host/zns.c | 1 + drivers/scsi/sd_zbc.c | 10 ++++++++++ include/linux/blkdev.h | 3 +++ 6 files changed, 56 insertions(+)