[PATCH v7 11/28] block: Allow BIO-based drivers to use blk_revalidate_disk_zones()

Damien Le Moal
2024-04-08T01:41:52Z

In preparation for allowing BIO based device drivers to use zone write
plugging and its zone append emulation, allow these drivers to call
blk_revalidate_disk_zones() so that all zone resources necessary to zone
write plugging can be initialized.

To do so, remove the check in blk_revalidate_disk_zones() restricting
the use of this function to mq request-based drivers to allow also
BIO-based drivers to use it. This is safe to do as long as the
BIO-based block device queue is already setup and usable, as it should,
and can be safely frozen.

The helper function disk_need_zone_resources() is added to control the
allocation and initialization of the zone write plug hash table and
of the conventional zone bitmap only for mq devices and for BIO-based
devices that require zone append emulation.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
---
block/blk-zoned.c | 30 ++++++++++++++++++++++++------
1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index a60ac5b3e637..da0fc7e2d00a 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -1512,12 +1512,28 @@ void disk_free_zone_resources(struct gendisk *disk)
disk->nr_zones = 0;
}

+static inline bool disk_need_zone_resources(struct gendisk *disk)
+{
+ /*
+ * All mq zoned devices need zone resources so that the block layer
+ * can automatically handle write BIO plugging. BIO-based device drivers
+ * (e.g. DM devices) are normally responsible for handling zone write
+ * ordering and do not need zone resources, unless the driver requires
+ * zone append emulation.
+ */
+ return queue_is_mq(disk->queue) ||
+ queue_emulates_zone_append(disk->queue);
+}
+
static int disk_revalidate_zone_resources(struct gendisk *disk,
unsigned int nr_zones)
{
struct queue_limits *lim = &disk->queue->limits;
unsigned int pool_size;

+ if (!disk_need_zone_resources(disk))
+ return 0;
+
/*
* If the device has no limit on the maximum number of open and active
* zones, use BLK_ZONE_WPLUG_DEFAULT_POOL_SIZE.
@@ -1635,6 +1651,9 @@ static int blk_revalidate_zone_cb(struct blk_zone *zone, unsigned int idx,
disk->disk_name);
return -ENODEV;
}
+
+ if (!disk_need_zone_resources(disk))
+ break;
if (!args->conv_zones_bitmap) {
args->conv_zones_bitmap =
blk_alloc_zone_bitmap(q->node, args->nr_zones);
@@ -1666,10 +1685,11 @@ static int blk_revalidate_zone_cb(struct blk_zone *zone, unsigned int idx,
/*
* We need to track the write pointer of all zones that are not
* empty nor full. So make sure we have a zone write plug for
- * such zone.
+ * such zone if the device has a zone write plug hash table.
*/
wp_offset = blk_zone_wp_offset(zone);
- if (wp_offset && wp_offset < zone_sectors) {
+ if (disk->zone_wplugs_hash &&
+ wp_offset && wp_offset < zone_sectors) {
zwplug = disk_get_and_lock_zone_wplug(disk, zone->start,
GFP_NOIO, &flags);
if (!zwplug)
@@ -1700,8 +1720,8 @@ static int blk_revalidate_zone_cb(struct blk_zone *zone, unsigned int idx,
* be called within the disk ->revalidate method for blk-mq based drivers.
* Before calling this function, the device driver must already have set the
* device zone size (chunk_sector limit) and the max zone append limit.
- * For BIO based drivers, this function cannot be used. BIO based device drivers
- * only need to set disk->nr_zones so that the sysfs exposed value is correct.
+ * BIO based drivers can also use this function as long as the device queue
+ * can be safely frozen.
* If the @update_driver_data callback function is not NULL, the callback is
* executed with the device request queue frozen after all zones have been
* checked.
@@ -1718,8 +1738,6 @@ int blk_revalidate_disk_zones(struct gendisk *disk,

if (WARN_ON_ONCE(!blk_queue_is_zoned(q)))
return -EIO;
- if (WARN_ON_ONCE(!queue_is_mq(q)))
- return -EIO;

if (!capacity)
return -ENODEV;
--
2.44.0