Commit cedcafad authored by Shaohua Li's avatar Shaohua Li Committed by Jens Axboe
Browse files

nullb: add interface to power on disk 



The device created in nullb configfs interface isn't power on by
default. After user configures the device, user can do 'echo 1 >
xxx/nullb/device_name/power' to power on the device, which will create a
disk. the xxx/nullb/device_name/index is the disk index, so if the index
is 2, the new created disk should be named as /dev/nullb2. Note, the
'index' is only valid after disk is power on.

'echo 0 > xxx/nullb/device_name/power' will remove the disk. Note, this
doesn't remove the device. To remove the device, user should do 'rmdir
xxx/nullb/device_name'. Removing the device will remove the disk too.

Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 3bf2bd20

drivers/block/null_blk.c

+80 −0
Original line number Diff line number Diff line
@@ -59,9 +59,11 @@ struct nullb_device { 
	unsigned int blocksize; /* block size */

	unsigned int irqmode; /* IRQ completion handler */

	unsigned int hw_queue_depth; /* queue depth */

	unsigned int index; /* index of the disk, only valid with a disk */

	bool use_lightnvm; /* register as a LightNVM device */

	bool blocking; /* blocking blk-mq device */

	bool use_per_node_hctx; /* use per-node allocation for hardware context */

	bool power; /* power on/off the device */

};



struct nullb {
@@ -193,6 +195,8 @@ MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware contex 


static struct nullb_device *null_alloc_dev(void);

static void null_free_dev(struct nullb_device *dev);

static void null_del_dev(struct nullb *nullb);

static int null_add_dev(struct nullb_device *dev);



static inline struct nullb_device *to_nullb_device(struct config_item *item)

{
@@ -284,10 +288,50 @@ NULLB_DEVICE_ATTR(queue_mode, uint); 
NULLB_DEVICE_ATTR(blocksize, uint);

NULLB_DEVICE_ATTR(irqmode, uint);

NULLB_DEVICE_ATTR(hw_queue_depth, uint);

NULLB_DEVICE_ATTR(index, uint);

NULLB_DEVICE_ATTR(use_lightnvm, bool);

NULLB_DEVICE_ATTR(blocking, bool);

NULLB_DEVICE_ATTR(use_per_node_hctx, bool);



static ssize_t nullb_device_power_show(struct config_item *item, char *page)

{

	return nullb_device_bool_attr_show(to_nullb_device(item)->power, page);

}



static ssize_t nullb_device_power_store(struct config_item *item,

				     const char *page, size_t count)

{

	struct nullb_device *dev = to_nullb_device(item);

	bool newp = false;

	ssize_t ret;



	ret = nullb_device_bool_attr_store(&newp, page, count);

	if (ret < 0)

		return ret;



	if (!dev->power && newp) {

		if (test_and_set_bit(NULLB_DEV_FL_UP, &dev->flags))

			return count;

		if (null_add_dev(dev)) {

			clear_bit(NULLB_DEV_FL_UP, &dev->flags);

			return -ENOMEM;

		}



		set_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);

		dev->power = newp;

	} else if (to_nullb_device(item)->power && !newp) {

		mutex_lock(&lock);

		dev->power = newp;

		null_del_dev(dev->nullb);

		mutex_unlock(&lock);

		clear_bit(NULLB_DEV_FL_UP, &dev->flags);

	}



	return count;

}



CONFIGFS_ATTR(nullb_device_, power);



static struct configfs_attribute *nullb_device_attrs[] = {

	&nullb_device_attr_size,

	&nullb_device_attr_completion_nsec,
@@ -297,9 +341,11 @@ static struct configfs_attribute *nullb_device_attrs[] = { 
	&nullb_device_attr_blocksize,

	&nullb_device_attr_irqmode,

	&nullb_device_attr_hw_queue_depth,

	&nullb_device_attr_index,

	&nullb_device_attr_use_lightnvm,

	&nullb_device_attr_blocking,

	&nullb_device_attr_use_per_node_hctx,

	&nullb_device_attr_power,

	NULL,

};
@@ -335,6 +381,15 @@ config_item *nullb_group_make_item(struct config_group *group, const char *name) 
static void

nullb_group_drop_item(struct config_group *group, struct config_item *item)

{

	struct nullb_device *dev = to_nullb_device(item);



	if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) {

		mutex_lock(&lock);

		dev->power = false;

		null_del_dev(dev->nullb);

		mutex_unlock(&lock);

	}



	config_item_put(item);

}
@@ -973,11 +1028,35 @@ static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set) 
	return blk_mq_alloc_tag_set(set);

}



static void null_validate_conf(struct nullb_device *dev)

{

	dev->blocksize = round_down(dev->blocksize, 512);

	dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);

	if (dev->use_lightnvm && dev->blocksize != 4096)

		dev->blocksize = 4096;



	if (dev->use_lightnvm && dev->queue_mode != NULL_Q_MQ)

		dev->queue_mode = NULL_Q_MQ;



	if (dev->queue_mode == NULL_Q_MQ && dev->use_per_node_hctx) {

		if (dev->submit_queues != nr_online_nodes)

			dev->submit_queues = nr_online_nodes;

	} else if (dev->submit_queues > nr_cpu_ids)

		dev->submit_queues = nr_cpu_ids;

	else if (dev->submit_queues == 0)

		dev->submit_queues = 1;



	dev->queue_mode = min_t(unsigned int, dev->queue_mode, NULL_Q_MQ);

	dev->irqmode = min_t(unsigned int, dev->irqmode, NULL_IRQ_TIMER);

}



static int null_add_dev(struct nullb_device *dev)

{

	struct nullb *nullb;

	int rv;



	null_validate_conf(dev);



	nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, dev->home_node);

	if (!nullb) {

		rv = -ENOMEM;
@@ -1040,6 +1119,7 @@ static int null_add_dev(struct nullb_device *dev) 


	mutex_lock(&lock);

	nullb->index = nullb_indexes++;

	dev->index = nullb->index;

	mutex_unlock(&lock);



	blk_queue_logical_block_size(nullb->q, dev->blocksize);

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