block: Allow BIO-based drivers to use blk_revalidate_disk_zones()

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>
Link: https://lore.kernel.org/r/20240408014128.205141-12-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index a60ac5b3e6379ee3e06a7d330b69626993e8e631..da0fc7e2d00ae88c2ef915131b3f2fe52af4ea43 100644 (file)
--- 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;