null_blk: add configfs variable shared_tags

Allow setting shared_tags through configfs, which could only be set as a
module parameter. For that purpose, delay tag_set initialization from
null_init() to null_add_dev(). Refer tag_set.ops as the flag to check if
tag_set is initialized or not.

The following parameters can not be set through configfs yet:

    timeout
    requeue
    init_hctx

Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20240130042134.2463659-1-shinichiro.kawasaki@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 36755f263e8ec03b1828bf44a05cc3b54bb6a03f..4281371c81fed12445a6f7d893682619c7d24872 100644 (file)
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -165,8 +165,8 @@ static bool g_blocking;
 module_param_named(blocking, g_blocking, bool, 0444);
 MODULE_PARM_DESC(blocking, "Register as a blocking blk-mq driver device");
 
-static bool shared_tags;
-module_param(shared_tags, bool, 0444);
+static bool g_shared_tags;
+module_param_named(shared_tags, g_shared_tags, bool, 0444);
 MODULE_PARM_DESC(shared_tags, "Share tag set between devices for blk-mq");
 
 static bool g_shared_tag_bitmap;
@@ -426,6 +426,7 @@ NULLB_DEVICE_ATTR(zone_max_open, uint, NULL);
 NULLB_DEVICE_ATTR(zone_max_active, uint, NULL);
 NULLB_DEVICE_ATTR(virt_boundary, bool, NULL);
 NULLB_DEVICE_ATTR(no_sched, bool, NULL);
+NULLB_DEVICE_ATTR(shared_tags, bool, NULL);
 NULLB_DEVICE_ATTR(shared_tag_bitmap, bool, NULL);
 
 static ssize_t nullb_device_power_show(struct config_item *item, char *page)
@@ -571,6 +572,7 @@ static struct configfs_attribute *nullb_device_attrs[] = {
        &nullb_device_attr_zone_offline,
        &nullb_device_attr_virt_boundary,
        &nullb_device_attr_no_sched,
+       &nullb_device_attr_shared_tags,
        &nullb_device_attr_shared_tag_bitmap,
        NULL,
 };
@@ -653,10 +655,11 @@ static ssize_t memb_group_features_show(struct config_item *item, char *page)
                        "badblocks,blocking,blocksize,cache_size,"
                        "completion_nsec,discard,home_node,hw_queue_depth,"
                        "irqmode,max_sectors,mbps,memory_backed,no_sched,"
-                       "poll_queues,power,queue_mode,shared_tag_bitmap,size,"
-                       "submit_queues,use_per_node_hctx,virt_boundary,zoned,"
-                       "zone_capacity,zone_max_active,zone_max_open,"
-                       "zone_nr_conv,zone_offline,zone_readonly,zone_size\n");
+                       "poll_queues,power,queue_mode,shared_tag_bitmap,"
+                       "shared_tags,size,submit_queues,use_per_node_hctx,"
+                       "virt_boundary,zoned,zone_capacity,zone_max_active,"
+                       "zone_max_open,zone_nr_conv,zone_offline,zone_readonly,"
+                       "zone_size\n");
 }
 
 CONFIGFS_ATTR_RO(memb_group_, features);
@@ -738,6 +741,7 @@ static struct nullb_device *null_alloc_dev(void)
        dev->zone_max_active = g_zone_max_active;
        dev->virt_boundary = g_virt_boundary;
        dev->no_sched = g_no_sched;
+       dev->shared_tags = g_shared_tags;
        dev->shared_tag_bitmap = g_shared_tag_bitmap;
        return dev;
 }
@@ -2124,7 +2128,14 @@ static int null_add_dev(struct nullb_device *dev)
                goto out_free_nullb;
 
        if (dev->queue_mode == NULL_Q_MQ) {
-               if (shared_tags) {
+               if (dev->shared_tags) {
+                       if (!tag_set.ops) {
+                               rv = null_init_tag_set(NULL, &tag_set);
+                               if (rv) {
+                                       tag_set.ops = NULL;
+                                       goto out_cleanup_queues;
+                               }
+                       }
                        nullb->tag_set = &tag_set;
                        rv = 0;
                } else {
@@ -2311,18 +2322,12 @@ static int __init null_init(void)
                g_submit_queues = 1;
        }
 
-       if (g_queue_mode == NULL_Q_MQ && shared_tags) {
-               ret = null_init_tag_set(NULL, &tag_set);
-               if (ret)
-                       return ret;
-       }
-
        config_group_init(&nullb_subsys.su_group);
        mutex_init(&nullb_subsys.su_mutex);
 
        ret = configfs_register_subsystem(&nullb_subsys);
        if (ret)
-               goto err_tagset;
+               return ret;
 
        mutex_init(&lock);
 
@@ -2349,9 +2354,6 @@ err_dev:
        unregister_blkdev(null_major, "nullb");
 err_conf:
        configfs_unregister_subsystem(&nullb_subsys);
-err_tagset:
-       if (g_queue_mode == NULL_Q_MQ && shared_tags)
-               blk_mq_free_tag_set(&tag_set);
        return ret;
 }
 
@@ -2370,7 +2372,7 @@ static void __exit null_exit(void)
        }
        mutex_unlock(&lock);
 
-       if (g_queue_mode == NULL_Q_MQ && shared_tags)
+       if (tag_set.ops)
                blk_mq_free_tag_set(&tag_set);
 }
 

diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index 929f659dd255b7068b74453099d46f965df7b30f..7bcfc0922ae8217b6ed62459c12e5d71ba8dd508 100644 (file)
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -119,6 +119,7 @@ struct nullb_device {
        bool zoned; /* if device is zoned */
        bool virt_boundary; /* virtual boundary on/off for the device */
        bool no_sched; /* no IO scheduler for the device */
+       bool shared_tags; /* share tag set between devices for blk-mq */
        bool shared_tag_bitmap; /* use hostwide shared tags */
 };