In preparation for a generic report zones command buffer allocation to
the block layer, introduce three new request queue limits describing the
device zone descriptor size (zone_descriptor_size limit), the needed
granularity of the report zones command buffer size
(zones_report_granularity limit) and the maximum size of a report zone
command (max_zones_report_size limit).
For scsi, set these values respectively to 64 bytes, SECTOR_SIZE and
the maximum transfer size used for regular read/write commands limited
by the maximum number of pages (segments) that the hardware can map.
This removes the need for the "magic" limit implemented with the macro
SD_ZBC_REPORT_MAX_ZONES.
For the null_blk driver and dm targets, the default value of 0 is used
for these limits, indicating that these zoned devices do not need a
buffer for the execution of report zones.
Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
---
block/blk-settings.c | 3 +++
drivers/scsi/sd_zbc.c | 48 +++++++++++++++++++++---------------------
include/linux/blkdev.h | 4 ++++
3 files changed, 31 insertions(+), 24 deletions(-)
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 5f6dcc7a47bd..674cfc428334 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -53,6 +53,9 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->discard_granularity = 0;
lim->discard_alignment = 0;
lim->discard_misaligned = 0;
+ lim->zone_descriptor_size = 0;
+ lim->zones_report_granularity = 0;
+ lim->max_zones_report_size = 0;
lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
lim->alignment_offset = 0;
diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
index fbec99db6124..8dc96f4ea920 100644
--- a/drivers/scsi/sd_zbc.c
+++ b/drivers/scsi/sd_zbc.c
@@ -104,11 +104,6 @@ static int sd_zbc_do_report_zones(struct scsi_disk *sdkp, unsigned char *buf,
return 0;
}
-/*
- * Maximum number of zones to get with one report zones command.
- */
-#define SD_ZBC_REPORT_MAX_ZONES 8192U
-
/**
* Allocate a buffer for report zones reply.
* @sdkp: The target disk
@@ -129,21 +124,8 @@ static void *sd_zbc_alloc_report_buffer(struct scsi_disk *sdkp,
size_t bufsize;
void *buf;
- /*
- * Report zone buffer size should be at most 64B times the number of
- * zones requested plus the 64B reply header, but should be at least
- * SECTOR_SIZE for ATA devices.
- * Make sure that this size does not exceed the hardware capabilities.
- * Furthermore, since the report zone command cannot be split, make
- * sure that the allocated buffer can always be mapped by limiting the
- * number of pages allocated to the HBA max segments limit.
- */
- nr_zones = min(nr_zones, SD_ZBC_REPORT_MAX_ZONES);
- bufsize = roundup((nr_zones + 1) * 64, 512);
- bufsize = min_t(size_t, bufsize,
- queue_max_hw_sectors(q) << SECTOR_SHIFT);
- bufsize = min_t(size_t, bufsize, queue_max_segments(q) << PAGE_SHIFT);
-
+ bufsize = min_t(size_t, roundup(nr_zones * 64, SECTOR_SIZE),
+ q->limits.max_zones_report_size);
buf = vzalloc(bufsize);
if (buf)
*buflen = bufsize;
@@ -398,6 +380,8 @@ static int sd_zbc_check_zones(struct scsi_disk *sdkp, unsigned char *buf,
int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buf)
{
struct gendisk *disk = sdkp->disk;
+ struct request_queue *q = disk->queue;
+ unsigned int max_zones_report_size;
unsigned int nr_zones;
u32 zone_blocks = 0;
int ret;
@@ -423,13 +407,29 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buf)
goto err;
/* The drive satisfies the kernel restrictions: set it up */
- blk_queue_chunk_sectors(sdkp->disk->queue,
+ blk_queue_chunk_sectors(q,
logical_to_sectors(sdkp->device, zone_blocks));
- blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, sdkp->disk->queue);
- blk_queue_required_elevator_features(sdkp->disk->queue,
- ELEVATOR_F_ZBD_SEQ_WRITE);
+ blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
+ blk_queue_required_elevator_features(q, ELEVATOR_F_ZBD_SEQ_WRITE);
nr_zones = round_up(sdkp->capacity, zone_blocks) >> ilog2(zone_blocks);
+ /*
+ * Zone descriptors are 64 bytes. A report zone buffer size should be
+ * at most 64B times the number of zones of the device plus a 64B reply
+ * header and should be at least be SECTOR_SIZE bytes for ATA devices.
+ * Make sure that this maximum buffer size does not exceed the hardware
+ * capabilities in terms of maximum data transfer size. Furthermore,
+ * make sure that the allocated buffer can always be mapped by limiting
+ * the number of pages of the buffer to the device max segments limit.
+ */
+ q->limits.zone_descriptor_size = 64;
+ q->limits.zones_report_granularity = SECTOR_SIZE;
+ max_zones_report_size = min(roundup((nr_zones + 1) * 64, SECTOR_SIZE),
+ queue_max_hw_sectors(q) << SECTOR_SHIFT);
+ q->limits.max_zones_report_size =
+ min(max_zones_report_size,
+ (unsigned int)queue_max_segments(q) << PAGE_SHIFT);
+
/* READ16/WRITE16 is mandatory for ZBC disks */
sdkp->device->use_16_for_rw = 1;
sdkp->device->use_10_for_rw = 0;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f3ea78b0c91c..1c76d71fc232 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -338,6 +338,10 @@ struct queue_limits {
unsigned int discard_granularity;
unsigned int discard_alignment;
+ unsigned int zone_descriptor_size;
+ unsigned int zones_report_granularity;
+ unsigned int max_zones_report_size;
+
unsigned short logical_block_size;
unsigned short max_segments;
unsigned short max_integrity_segments;
--
2.21.0
