[PATCH 5/5] lightnvm: null_blk integration

From: Matias BjÃrling
Date: Wed Oct 08 2014 - 11:57:58 EST

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Allows the null_blk driver to hook into LightNVM for performance
evaluation. The number of channels exposed to LightNVM can be configured
through the lightnvm_num_channels module parameter.

Contributions in this patch from:

Jesper Madsen <jmad@xxxxxx>

Signed-off-by: Matias BjÃrling <m@xxxxxxxxxxx>
---
Documentation/block/null_blk.txt | 9 +++
drivers/block/null_blk.c | 149 +++++++++++++++++++++++++++++++++++----
2 files changed, 144 insertions(+), 14 deletions(-)

diff --git a/Documentation/block/null_blk.txt b/Documentation/block/null_blk.txt
index b2830b4..639d378 100644
--- a/Documentation/block/null_blk.txt
+++ b/Documentation/block/null_blk.txt
@@ -14,6 +14,9 @@ The following instances are possible:
Multi-queue block-layer
- Request-based.
- Configurable submission queues per device.
+ LightNVM compatible
+ - Request-based.
+ - Same configuration as the multi-queue block layer.
No block-layer (Known as bio-based)
- Bio-based. IO requests are submitted directly to the device driver.
- Directly accepts bio data structure and returns them.
@@ -28,6 +31,7 @@ queue_mode=[0-2]: Default: 2-Multi-queue
0: Bio-based.
1: Single-queue.
2: Multi-queue.
+ 3: LightNVM device with multi-queue.

home_node=[0--nr_nodes]: Default: NUMA_NO_NODE
Selects what CPU node the data structures are allocated from.
@@ -70,3 +74,8 @@ use_per_node_hctx=[0/1]: Default: 0
parameter.
1: The multi-queue block layer is instantiated with a hardware dispatch
queue for each CPU node in the system.
+
+IV: LightNVM specific parameters
+
+lightnvm_num_channels=[x]: Default: 1
+ Number of LightNVM channels that are exposed to the LightNVM driver.
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 00d469c..2f679b1 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -7,6 +7,7 @@
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/blk-mq.h>
+#include <linux/lightnvm.h>
#include <linux/hrtimer.h>

struct nullb_cmd {
@@ -25,6 +26,7 @@ struct nullb_queue {
unsigned int queue_depth;

struct nullb_cmd *cmds;
+ struct nullb *nb;
};

struct nullb {
@@ -33,6 +35,7 @@ struct nullb {
struct request_queue *q;
struct gendisk *disk;
struct blk_mq_tag_set tag_set;
+ struct nvm_dev *nvm_dev;
struct hrtimer timer;
unsigned int queue_depth;
spinlock_t lock;
@@ -67,6 +70,7 @@ enum {
NULL_Q_BIO = 0,
NULL_Q_RQ = 1,
NULL_Q_MQ = 2,
+ NULL_Q_LIGHTNVM = 4,
};

static int submit_queues;
@@ -79,7 +83,7 @@ MODULE_PARM_DESC(home_node, "Home node for the device");

static int queue_mode = NULL_Q_MQ;
module_param(queue_mode, int, S_IRUGO);
-MODULE_PARM_DESC(queue_mode, "Block interface to use (0=bio,1=rq,2=multiqueue)");
+MODULE_PARM_DESC(queue_mode, "Block interface to use (0=bio,1=rq,2=multiqueue,4=lightnvm)");

static int gb = 250;
module_param(gb, int, S_IRUGO);
@@ -109,6 +113,10 @@ static bool use_per_node_hctx = false;
module_param(use_per_node_hctx, bool, S_IRUGO);
MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false");

+static int lightnvm_num_channels = 1;
+module_param(lightnvm_num_channels, int, S_IRUGO);
+MODULE_PARM_DESC(lightnvm_num_channels, "Number of channels to be exposed to LightNVM. Default: 1");
+
static void put_tag(struct nullb_queue *nq, unsigned int tag)
{
clear_bit_unlock(tag, nq->tag_map);
@@ -179,6 +187,9 @@ static void end_cmd(struct nullb_cmd *cmd)
case NULL_Q_MQ:
blk_mq_end_io(cmd->rq, 0);
return;
+ case NULL_Q_LIGHTNVM:
+ nvm_end_io(cmd->nq->nb->nvm_dev, cmd->rq, 0);
+ return;
case NULL_Q_RQ:
INIT_LIST_HEAD(&cmd->rq->queuelist);
blk_end_request_all(cmd->rq, 0);
@@ -227,7 +238,7 @@ static void null_cmd_end_timer(struct nullb_cmd *cmd)

static void null_softirq_done_fn(struct request *rq)
{
- if (queue_mode == NULL_Q_MQ)
+ if (queue_mode & (NULL_Q_MQ|NULL_Q_LIGHTNVM))
end_cmd(blk_mq_rq_to_pdu(rq));
else
end_cmd(rq->special);
@@ -239,6 +250,7 @@ static inline void null_handle_cmd(struct nullb_cmd *cmd)
switch (irqmode) {
case NULL_IRQ_SOFTIRQ:
switch (queue_mode) {
+ case NULL_Q_LIGHTNVM:
case NULL_Q_MQ:
blk_mq_complete_request(cmd->rq);
break;
@@ -313,14 +325,67 @@ static void null_request_fn(struct request_queue *q)
}
}

+static int null_nvm_id(struct nvm_dev *dev, struct nvm_id *nvm_id)
+{
+ nvm_id->ver_id = 0x1;
+ nvm_id->nvm_type = NVM_NVMT_BLK;
+ nvm_id->nchannels = lightnvm_num_channels;
+ return 0;
+}
+
+static int null_nvm_id_chnl(struct nvm_dev *dev, int chnl_num,
+ struct nvm_id_chnl *ic)
+{
+ sector_t size = gb * 1024 * 1024 * 1024ULL;
+
+ sector_div(size, bs);
+ ic->queue_size = hw_queue_depth;
+ ic->gran_read = bs;
+ ic->gran_write = bs;
+ ic->gran_erase = bs * 256;
+ ic->oob_size = 0;
+ ic->t_r = ic->t_sqr = 25000; /* 25us */
+ ic->t_w = ic->t_sqw = 500000; /* 500us */
+ ic->t_e = 1500000; /* 1.500us */
+ ic->io_sched = NVM_IOSCHED_CHANNEL;
+ ic->laddr_begin = 0;
+ ic->laddr_end = size / 8;
+
+ return 0;
+}
+
+static int null_nvm_get_features(struct nvm_dev *dev,
+ struct nvm_get_features *gf)
+{
+ gf->rsp[0] = (1 << NVM_RSP_L2P);
+ gf->rsp[0] |= (1 << NVM_RSP_P2L);
+ gf->rsp[0] |= (1 << NVM_RSP_GC);
+ return 0;
+}
+
+static int null_nvm_set_rsp(struct nvm_dev *dev, u8 rsp, u8 val)
+{
+ return NVM_RID_NOT_CHANGEABLE | NVM_DNR;
+}
+
static int null_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *rq)
{
struct nullb_cmd *cmd = blk_mq_rq_to_pdu(rq);
+ struct nullb_queue *nq = hctx->driver_data;
+ struct nvm_dev *nvm_dev = nq->nb->nvm_dev;
+ int ret = BLK_MQ_RQ_QUEUE_OK;
+
+ if (nvm_dev) {
+ ret = nvm_queue_rq(nvm_dev, rq);
+ if (ret)
+ goto out;
+ }

cmd->rq = rq;
- cmd->nq = hctx->driver_data;
+ cmd->nq = nq;

null_handle_cmd(cmd);
+out:
return BLK_MQ_RQ_QUEUE_OK;
}

@@ -331,6 +396,7 @@ static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq)

init_waitqueue_head(&nq->wait);
nq->queue_depth = nullb->queue_depth;
+ nq->nb = nullb;
}

static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
@@ -346,6 +412,13 @@ static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
return 0;
}

+static struct lightnvm_dev_ops null_nvm_dev_ops = {
+ .identify = null_nvm_id,
+ .identify_channel = null_nvm_id_chnl,
+ .get_features = null_nvm_get_features,
+ .set_responsibility = null_nvm_set_rsp,
+};
+
static struct blk_mq_ops null_mq_ops = {
.queue_rq = null_queue_rq,
.map_queue = blk_mq_map_queue,
@@ -359,8 +432,11 @@ static void null_del_dev(struct nullb *nullb)

del_gendisk(nullb->disk);
blk_cleanup_queue(nullb->q);
- if (queue_mode == NULL_Q_MQ)
+ if (queue_mode & (NULL_Q_MQ|NULL_Q_LIGHTNVM)) {
+ if (queue_mode == NULL_Q_LIGHTNVM)
+ nvm_remove_sysfs(nullb->disk->private_data);
blk_mq_free_tag_set(&nullb->tag_set);
+ }
put_disk(nullb->disk);
kfree(nullb);
}
@@ -374,10 +450,26 @@ static void null_release(struct gendisk *disk, fmode_t mode)
{
}

+static int null_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd,
+ unsigned long arg)
+{
+ struct nullb *nullb = bdev->bd_disk->private_data;
+ int ret;
+
+ if (nullb->nvm_dev) {
+ ret = nvm_ioctl(nullb->nvm_dev, mode, cmd, arg);
+ if (ret != -ENOTTY)
+ return ret;
+ }
+
+ return -ENOTTY;
+};
+
static const struct block_device_operations null_fops = {
.owner = THIS_MODULE,
.open = null_open,
.release = null_release,
+ .ioctl = null_ioctl,
};

static int setup_commands(struct nullb_queue *nq)
@@ -461,6 +553,7 @@ static int null_add_dev(void)
{
struct gendisk *disk;
struct nullb *nullb;
+ struct nvm_dev *nvm_dev = NULL;
sector_t size;
int rv;

@@ -472,14 +565,14 @@ static int null_add_dev(void)

spin_lock_init(&nullb->lock);

- if (queue_mode == NULL_Q_MQ && use_per_node_hctx)
+ if ((queue_mode & (NULL_Q_MQ|NULL_Q_LIGHTNVM)) && use_per_node_hctx)
submit_queues = nr_online_nodes;

rv = setup_queues(nullb);
if (rv)
goto out_free_nullb;

- if (queue_mode == NULL_Q_MQ) {
+ if (queue_mode & (NULL_Q_MQ|NULL_Q_LIGHTNVM)) {
nullb->tag_set.ops = &null_mq_ops;
nullb->tag_set.nr_hw_queues = submit_queues;
nullb->tag_set.queue_depth = hw_queue_depth;
@@ -497,6 +590,18 @@ static int null_add_dev(void)
rv = -ENOMEM;
goto out_cleanup_tags;
}
+
+ if (queue_mode == NULL_Q_LIGHTNVM) {
+ nvm_dev = nvm_alloc();
+ if (!nvm_dev)
+ goto out_cleanup_tags;
+
+ nvm_dev->ops = &null_nvm_dev_ops;
+ nvm_dev->driver_data = nullb;
+
+ nvm_dev->drv_cmd_size = nullb->tag_set.cmd_size;
+ nullb->tag_set.cmd_size += nvm_cmd_size();
+ }
} else if (queue_mode == NULL_Q_BIO) {
nullb->q = blk_alloc_queue_node(GFP_KERNEL, home_node);
if (!nullb->q) {
@@ -517,6 +622,7 @@ static int null_add_dev(void)
}

nullb->q->queuedata = nullb;
+
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q);

disk = nullb->disk = alloc_disk_node(1, home_node);
@@ -525,11 +631,6 @@ static int null_add_dev(void)
goto out_cleanup_blk_queue;
}

- mutex_lock(&lock);
- list_add_tail(&nullb->list, &nullb_list);
- nullb->index = nullb_indexes++;
- mutex_unlock(&lock);
-
blk_queue_logical_block_size(nullb->q, bs);
blk_queue_physical_block_size(nullb->q, bs);

@@ -540,17 +641,37 @@ static int null_add_dev(void)
disk->flags |= GENHD_FL_EXT_DEVT;
disk->major = null_major;
disk->first_minor = nullb->index;
- disk->fops = &null_fops;
disk->private_data = nullb;
+ disk->fops = &null_fops;
disk->queue = nullb->q;
+
+ if (nvm_dev) {
+ nvm_dev->q = nullb->q;
+ nvm_dev->disk = disk;
+
+ if (nvm_init(disk, nvm_dev))
+ goto out_cleanup_nvm;
+
+ nullb->nvm_dev = nvm_dev;
+ }
+
+ mutex_lock(&lock);
+ list_add_tail(&nullb->list, &nullb_list);
+ nullb->index = nullb_indexes++;
+ mutex_unlock(&lock);
+
sprintf(disk->disk_name, "nullb%d", nullb->index);
add_disk(disk);
+ nvm_add_sysfs(nvm_dev);
return 0;

+out_cleanup_nvm:
+ put_disk(disk);
out_cleanup_blk_queue:
blk_cleanup_queue(nullb->q);
out_cleanup_tags:
- if (queue_mode == NULL_Q_MQ)
+ nvm_free(nvm_dev);
+ if (queue_mode & (NULL_Q_MQ|NULL_Q_LIGHTNVM))
blk_mq_free_tag_set(&nullb->tag_set);
out_cleanup_queues:
cleanup_queues(nullb);
@@ -570,7 +691,7 @@ static int __init null_init(void)
bs = PAGE_SIZE;
}

- if (queue_mode == NULL_Q_MQ && use_per_node_hctx) {
+ if (queue_mode & (NULL_Q_MQ|NULL_Q_LIGHTNVM) && use_per_node_hctx) {
if (submit_queues < nr_online_nodes) {
pr_warn("null_blk: submit_queues param is set to %u.",
nr_online_nodes);
--
1.9.1

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