Zoned block devices have no write constraints for conventional zones
so write locking of conventional zones is not necessary and can hurt
performance. To avoid this, introduce the seq_zones bitmap to indicate
if a zone is a sequential one. Use this information to allow any write
to be issued to conventional zones, locking only sequential zones.
As the zone bitmap allocation for seq_zones is identical to the zones
write lock bitmap, introduce the helper sd_zbc_alloc_zone_bitmap().
Using this helper, wait for the disk capacity and number of zones to
stabilize on the second revalidation pass to allocate and initialize
the bitmaps.
Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
Reviewed-by: Bart Van Assche <Bart.VanAssche@xxxxxxx>
---
drivers/scsi/sd.h | 1 +
drivers/scsi/sd_zbc.c | 108 ++++++++++++++++++++++++++++++++++++++++++++------
drivers/scsi/sd_zbc.h | 12 ++++++
3 files changed, 108 insertions(+), 13 deletions(-)
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index c9a627e7eebd..3ea82c8cecd5 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -77,6 +77,7 @@ struct scsi_disk {
unsigned int zone_blocks;
unsigned int zone_shift;
unsigned long *zones_wlock;
+ unsigned long *seq_zones;
unsigned int zones_optimal_open;
unsigned int zones_optimal_nonseq;
unsigned int zones_max_open;
diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
index 8b258254a2bb..bcece82a1d8d 100644
--- a/drivers/scsi/sd_zbc.c
+++ b/drivers/scsi/sd_zbc.c
@@ -252,7 +252,7 @@ int sd_zbc_write_lock_zone(struct scsi_cmnd *cmd)
struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
sector_t sector = blk_rq_pos(rq);
sector_t zone_sectors = sd_zbc_zone_sectors(sdkp);
- unsigned int zno = sd_zbc_zone_no(sdkp, sector);
+ unsigned int zno;
/*
* Note: Checks of the alignment of the write command on
@@ -265,13 +265,15 @@ int sd_zbc_write_lock_zone(struct scsi_cmnd *cmd)
return BLKPREP_KILL;
/*
- * Do not issue more than one write at a time per
- * zone. This solves write ordering problems due to
- * the unlocking of the request queue in the dispatch
- * path in the non scsi-mq case.
+ * There is no write constraint on conventional zones, but do not issue
+ * more than one write at a time per sequential zone. This avoids write
+ * ordering problems due to the unlocking of the request queue in the
+ * dispatch path of the non scsi-mq (legacy) case.
*/
- if (sdkp->zones_wlock &&
- test_and_set_bit(zno, sdkp->zones_wlock))
+ zno = sd_zbc_zone_no(sdkp, sector);
+ if (!test_bit(zno, sdkp->seq_zones))
+ return BLKPREP_OK;
+ if (test_and_set_bit(zno, sdkp->zones_wlock))
return BLKPREP_DEFER;
WARN_ON_ONCE(cmd->flags & SCMD_ZONE_WRITE_LOCK);
@@ -289,8 +291,9 @@ void sd_zbc_write_unlock_zone(struct scsi_cmnd *cmd)
struct request *rq = cmd->request;
struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
- if (sdkp->zones_wlock && cmd->flags & SCMD_ZONE_WRITE_LOCK) {
+ if (cmd->flags & SCMD_ZONE_WRITE_LOCK) {
unsigned int zno = sd_zbc_zone_no(sdkp, blk_rq_pos(rq));
+
WARN_ON_ONCE(!test_bit(zno, sdkp->zones_wlock));
cmd->flags &= ~SCMD_ZONE_WRITE_LOCK;
clear_bit_unlock(zno, sdkp->zones_wlock);
@@ -507,8 +510,67 @@ static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
return 0;
}
+/*
+ * Initialize the sequential zone bitmap to allow identifying sequential zones.
+ */
+static int sd_zbc_setup_seq_zones(struct scsi_disk *sdkp)
+{
+ unsigned long *seq_zones;
+ sector_t block = 0;
+ unsigned char *buf;
+ unsigned char *rec;
+ unsigned int buf_len;
+ unsigned int list_length;
+ unsigned int n = 0;
+ int ret = -ENOMEM;
+
+ /* Allocate zone type bitmap */
+ seq_zones = sd_zbc_alloc_zone_bitmap(sdkp);
+ if (!seq_zones)
+ return -ENOMEM;
+
+ buf = kmalloc(SD_ZBC_BUF_SIZE, GFP_KERNEL);
+ if (!buf)
+ goto out;
+
+ while (block < sdkp->capacity) {
+
+ ret = sd_zbc_report_zones(sdkp, buf, SD_ZBC_BUF_SIZE, block);
+ if (ret)
+ goto out;
+
+ /* Parse reported zone descriptors */
+ list_length = get_unaligned_be32(&buf[0]) + 64;
+ rec = buf + 64;
+ buf_len = min(list_length, SD_ZBC_BUF_SIZE);
+ while (rec < buf + buf_len) {
+ if ((rec[0] & 0x0f) != ZBC_ZONE_TYPE_CONV)
+ set_bit(n, seq_zones);
+ block += get_unaligned_be64(&rec[8]);
+ rec += 64;
+ n++;
+ }
+
+ }
+
+ if (n != sdkp->nr_zones)
+ ret = -EIO;
+
+out:
+ kfree(buf);
+ if (ret) {
+ kfree(seq_zones);
+ return ret;
+ }
+
+ sdkp->seq_zones = seq_zones;
+
+ return 0;
+}
+
static int sd_zbc_setup(struct scsi_disk *sdkp)
{
+ int ret;
/* READ16/WRITE16 is mandatory for ZBC disks */
sdkp->device->use_16_for_rw = 1;
@@ -520,17 +582,37 @@ static int sd_zbc_setup(struct scsi_disk *sdkp)
sdkp->nr_zones =
round_up(sdkp->capacity, sdkp->zone_blocks) >> sdkp->zone_shift;
+ /*
+ * Wait for the disk capacity to stabilize before
+ * initializing zone related information.
+ */
+ if (sdkp->first_scan)
+ return 0;
+
if (!sdkp->zones_wlock) {
- sdkp->zones_wlock = kcalloc(BITS_TO_LONGS(sdkp->nr_zones),
- sizeof(unsigned long),
- GFP_KERNEL);
+ sdkp->zones_wlock = sd_zbc_alloc_zone_bitmap(sdkp);
if (!sdkp->zones_wlock)
return -ENOMEM;
}
+ if (!sdkp->seq_zones) {
+ ret = sd_zbc_setup_seq_zones(sdkp);
+ if (ret)
+ return ret;
+ }
+
return 0;
}
+static void sd_zbc_cleanup(struct scsi_disk *sdkp)
+{
+ kfree(sdkp->seq_zones);
+ sdkp->seq_zones = NULL;
+
+ kfree(sdkp->zones_wlock);
+ sdkp->zones_wlock = NULL;
+}
+
int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buf)
{
int ret;
@@ -582,14 +664,14 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buf)
err:
sdkp->capacity = 0;
+ sd_zbc_cleanup(sdkp);
return ret;
}
void sd_zbc_remove(struct scsi_disk *sdkp)
{
- kfree(sdkp->zones_wlock);
- sdkp->zones_wlock = NULL;
+ sd_zbc_cleanup(sdkp);
}
void sd_zbc_print_zones(struct scsi_disk *sdkp)
diff --git a/drivers/scsi/sd_zbc.h b/drivers/scsi/sd_zbc.h
index b34002f0acbe..2b63ee352fa2 100644
--- a/drivers/scsi/sd_zbc.h
+++ b/drivers/scsi/sd_zbc.h
@@ -32,6 +32,18 @@ static inline unsigned int sd_zbc_zone_no(struct scsi_disk *sdkp,
return sectors_to_logical(sdkp->device, sector) >> sdkp->zone_shift;
}
+/*
+ * Allocate a zone bitmap (one bit per zone).
+ */
+static inline unsigned long *sd_zbc_alloc_zone_bitmap(struct scsi_disk *sdkp)
+{
+ struct request_queue *q = sdkp->disk->queue;
+
+ return kzalloc_node(BITS_TO_LONGS(sdkp->nr_zones)
+ * sizeof(unsigned long),
+ GFP_KERNEL, q->node);
+}
+
#else /* CONFIG_BLK_DEV_ZONED */
static inline int sd_zbc_read_zones(struct scsi_disk *sdkp,
--
2.13.5
