Re: [PATCH v12 03/13] block: allow blk-zoned devices to have non-power-of-2 zone size
From: Jonathan Derrick
Date: Fri Aug 26 2022 - 16:09:33 EST
On 8/26/2022 2:06 PM, Jonathan Derrick wrote:
On 8/23/2022 6:18 AM, Pankaj Raghav wrote:
Checking if a given sector is aligned to a zone is a common
operation that is performed for zoned devices. Add
bdev_is_zone_start helper to check for this instead of opencoding it
everywhere.
Convert the calculations on zone size to be generic instead of relying on
power-of-2(po2) based arithmetic in the block layer using the helpers
wherever possible.
The only hot path affected by this change for zoned devices with po2
zone size is in blk_check_zone_append() but bdev_is_zone_start()
helper is
used to optimize the calculation for po2 zone sizes.
Finally, allow zoned devices with non po2 zone sizes provided that their
zone capacity and zone size are equal. The main motivation to allow zoned
devices with non po2 zone size is to remove the unmapped LBA between
zone capcity and zone size for devices that cannot have a po2 zone
capacity.
Reviewed-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
---
block/blk-core.c | 2 +-
block/blk-zoned.c | 24 ++++++++++++++++++------
include/linux/blkdev.h | 30 ++++++++++++++++++++++++++++++
3 files changed, 49 insertions(+), 7 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index a0d1104c5590..1cb519220ffb 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -563,7 +563,7 @@ static inline blk_status_t
blk_check_zone_append(struct request_queue *q,
return BLK_STS_NOTSUPP;
/* The bio sector must point to the start of a sequential zone */
- if (bio->bi_iter.bi_sector & (bdev_zone_sectors(bio->bi_bdev) -
1) ||
+ if (!bdev_is_zone_start(bio->bi_bdev, bio->bi_iter.bi_sector) ||
!bio_zone_is_seq(bio))
return BLK_STS_IOERR;
diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index dce9c95b4bcd..6806c69c81dc 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -285,10 +285,10 @@ int blkdev_zone_mgmt(struct block_device *bdev,
enum req_op op,
return -EINVAL;
/* Check alignment (handle eventual smaller last zone) */
- if (sector & (zone_sectors - 1))
+ if (!bdev_is_zone_start(bdev, sector))
return -EINVAL;
- if ((nr_sectors & (zone_sectors - 1)) && end_sector != capacity)
+ if (!bdev_is_zone_start(bdev, nr_sectors) && end_sector != capacity)
return -EINVAL;
/*
@@ -486,14 +486,26 @@ static int blk_revalidate_zone_cb(struct
blk_zone *zone, unsigned int idx,
* smaller last zone.
*/
if (zone->start == 0) {
- if (zone->len == 0 || !is_power_of_2(zone->len)) {
- pr_warn("%s: Invalid zoned device with non power of two
zone size (%llu)\n",
- disk->disk_name, zone->len);
+ if (zone->len == 0) {
+ pr_warn("%s: Invalid zero zone size", disk->disk_name);
+ return -ENODEV;
+ }
+
+ /*
+ * Non power-of-2 zone size support was added to remove the
+ * gap between zone capacity and zone size. Though it is
technically
+ * possible to have gaps in a non power-of-2 device, Linux
requires
+ * the zone size to be equal to zone capacity for non power-of-2
+ * zoned devices.
+ */
+ if (!is_power_of_2(zone->len) && zone->capacity < zone->len) {
+ pr_err("%s: Invalid zone capacity %lld with non
power-of-2 zone size %lld",
+ disk->disk_name, zone->capacity, zone->len);
return -ENODEV;
}
args->zone_sectors = zone->len;
- args->nr_zones = (capacity + zone->len - 1) >> ilog2(zone->len);
+ args->nr_zones = div64_u64(capacity + zone->len - 1, zone->len);
} else if (zone->start + args->zone_sectors < capacity) {
if (zone->len != args->zone_sectors) {
pr_warn("%s: Invalid zoned device with non constant zone
size\n",
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 84e7881262e3..d0d66a0db224 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -704,6 +704,30 @@ static inline unsigned int disk_zone_no(struct
gendisk *disk, sector_t sector)
return div64_u64(sector, zone_sectors);
}
+static inline sector_t bdev_offset_from_zone_start(struct
block_device *bdev,
+ sector_t sec)
+{
+ sector_t zone_sectors = bdev_zone_sectors(bdev);
+ u64 remainder = 0;
+
+ if (!bdev_is_zoned(bdev))
+ return 0;
See below
+
+ if (is_power_of_2(zone_sectors))
+ return sec & (zone_sectors - 1);
+
+ div64_u64_rem(sec, zone_sectors, &remainder);
+ return remainder;
+}
+
+static inline bool bdev_is_zone_start(struct block_device *bdev,
sector_t sec)
+{
+ if (!bdev_is_zoned(bdev))
+ return false;
Duplicating the same check above, and the check above is less clear in
the case of !zoned since it returns 0 and not some warning that makes
sense in the case of zoned check on !zoned bdev.
Can you simply exclude above check?
Nevermind, just noticed bdev_offset_from_zone_start is used in later
patches.
+
+ return bdev_offset_from_zone_start(bdev, sec) == 0;
+}
+
static inline bool disk_zone_is_seq(struct gendisk *disk, sector_t
sector)
{
if (!blk_queue_is_zoned(disk->queue))
@@ -748,6 +772,12 @@ static inline unsigned int disk_zone_no(struct
gendisk *disk, sector_t sector)
{
return 0;
}
+
+static inline bool bdev_is_zone_start(struct block_device *bdev,
sector_t sec)
+{
+ return false;
+}
+
static inline unsigned int bdev_max_open_zones(struct block_device
*bdev)
{
return 0;