From: Shaohua Li <shli@xxxxxx>
Add configfs interface for nullb. configfs interface is more flexible
and easy to configure in a per-disk basis.
Configuration is something like this:
mount -t configfs none /mnt
Checking which features the driver supports:
cat /mnt/nullb/features
The 'features' attribute is for future extension. We probably will add
new features into the driver, userspace can check this attribute to find
the supported features.
Create/remove a device:
mkdir/rmdir /mnt/nullb/a
Then configure the device by setting attributes under /mnt/nullb/a, most
of nullb supported module parameters are converted to attributes:
size; /* device size in MB */
completion_nsec; /* time in ns to complete a request */
submit_queues; /* number of submission queues */
home_node; /* home node for the device */
queue_mode; /* block interface */
blocksize; /* block size */
irqmode; /* IRQ completion handler */
hw_queue_depth; /* queue depth */
use_lightnvm; /* register as a LightNVM device */
blocking; /* blocking blk-mq device */
use_per_node_hctx; /* use per-node allocation for hardware context */
Note, creating a device doesn't create a disk immediately. Creating a
disk is done in two phases: create a device and then power on the
device. Next patch will introduce device power on.
Based on original patch from Kyungchan Koh
Signed-off-by: Kyungchan Koh <kkc6196@xxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxx>
---
drivers/block/Kconfig | 1 +
drivers/block/null_blk.c | 210 ++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 210 insertions(+), 1 deletion(-)
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index 8ddc982..5dd62a8 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -17,6 +17,7 @@ if BLK_DEV
config BLK_DEV_NULL_BLK
tristate "Null test block driver"
+ depends on CONFIGFS_FS
config BLK_DEV_FD
tristate "Normal floppy disk support"
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 73938cd..c782492 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -1,3 +1,7 @@
+/*
+ * Add configfs and memory store: Kyungchan Koh <kkc6196@xxxxxx> and
+ * Shaohua Li <shli@xxxxxx>
+ */
#include <linux/module.h>
#include <linux/moduleparam.h>
@@ -9,6 +13,7 @@
#include <linux/blk-mq.h>
#include <linux/hrtimer.h>
#include <linux/lightnvm.h>
+#include <linux/configfs.h>
struct nullb_cmd {
struct list_head list;
@@ -30,8 +35,21 @@ struct nullb_queue {
struct nullb_cmd *cmds;
};
+/*
+ * Status flags for nullb_device.
+ *
+ * CONFIGURED: Device has been configured and turned on. Cannot reconfigure.
+ * UP: Device is currently on and visible in userspace.
+ */
+enum nullb_device_flags {
+ NULLB_DEV_FL_CONFIGURED = 0,
+ NULLB_DEV_FL_UP = 1,
+};
+
struct nullb_device {
struct nullb *nullb;
+ struct config_item item;
+ unsigned long flags; /* device flags */
unsigned long size; /* device size in MB */
unsigned long completion_nsec; /* time in ns to complete a request */
@@ -173,6 +191,185 @@ static bool g_use_per_node_hctx;
module_param_named(use_per_node_hctx, g_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 struct nullb_device *null_alloc_dev(void);
+static void null_free_dev(struct nullb_device *dev);
+
+static inline struct nullb_device *to_nullb_device(struct config_item *item)
+{
+ return item ? container_of(item, struct nullb_device, item) : NULL;
+}
+
+static inline ssize_t nullb_device_uint_attr_show(unsigned int val, char *page)
+{
+ return snprintf(page, PAGE_SIZE, "%u\n", val);
+}
+
+static inline ssize_t nullb_device_ulong_attr_show(unsigned long val,
+ char *page)
+{
+ return snprintf(page, PAGE_SIZE, "%lu\n", val);
+}
+
+static inline ssize_t nullb_device_bool_attr_show(bool val, char *page)
+{
+ return snprintf(page, PAGE_SIZE, "%u\n", val);
+}
+
+static ssize_t nullb_device_uint_attr_store(unsigned int *val,
+ const char *page, size_t count)
+{
+ unsigned int tmp;
+ int result;
+
+ result = kstrtouint(page, 0, &tmp);
+ if (result)
+ return result;
+
+ *val = tmp;
+ return count;
+}
+
+static ssize_t nullb_device_ulong_attr_store(unsigned long *val,
+ const char *page, size_t count)
+{
+ int result;
+ unsigned long tmp;
+
+ result = kstrtoul(page, 0, &tmp);
+ if (result)
+ return result;
+
+ *val = tmp;
+ return count;
+}
+
+static ssize_t nullb_device_bool_attr_store(bool *val, const char *page,
+ size_t count)
+{
+ bool tmp;
+ int result;
+
+ result = kstrtobool(page, &tmp);
+ if (result)
+ return result;
+
+ *val = tmp;
+ return count;
+}
+
+/* The following macro should only be used with TYPE = {uint, ulong, bool}. */
+#define NULLB_DEVICE_ATTR(NAME, TYPE) \
+static ssize_t \
+nullb_device_##NAME##_show(struct config_item *item, char *page) \
+{ \
+ return nullb_device_##TYPE##_attr_show( \
+ to_nullb_device(item)->NAME, page); \
+} \
+static ssize_t \
+nullb_device_##NAME##_store(struct config_item *item, const char *page, \
+ size_t count) \
+{ \
+ if (test_bit(NULLB_DEV_FL_CONFIGURED, &to_nullb_device(item)->flags)) \
+ return -EBUSY; \
+ return nullb_device_##TYPE##_attr_store( \
+ &to_nullb_device(item)->NAME, page, count); \
+} \
+CONFIGFS_ATTR(nullb_device_, NAME);
+
+NULLB_DEVICE_ATTR(size, ulong);
+NULLB_DEVICE_ATTR(completion_nsec, ulong);
+NULLB_DEVICE_ATTR(submit_queues, uint);
+NULLB_DEVICE_ATTR(home_node, uint);
+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(use_lightnvm, bool);
+NULLB_DEVICE_ATTR(blocking, bool);
+NULLB_DEVICE_ATTR(use_per_node_hctx, bool);
+
+static struct configfs_attribute *nullb_device_attrs[] = {
+ &nullb_device_attr_size,
+ &nullb_device_attr_completion_nsec,
+ &nullb_device_attr_submit_queues,
+ &nullb_device_attr_home_node,
+ &nullb_device_attr_queue_mode,
+ &nullb_device_attr_blocksize,
+ &nullb_device_attr_irqmode,
+ &nullb_device_attr_hw_queue_depth,
+ &nullb_device_attr_use_lightnvm,
+ &nullb_device_attr_blocking,
+ &nullb_device_attr_use_per_node_hctx,
+ NULL,
+};
+
+static void nullb_device_release(struct config_item *item)
+{
+ null_free_dev(to_nullb_device(item));
+}
+
+static struct configfs_item_operations nullb_device_ops = {
+ .release = nullb_device_release,
+};
+
+static struct config_item_type nullb_device_type = {
+ .ct_item_ops = &nullb_device_ops,
+ .ct_attrs = nullb_device_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+static struct
+config_item *nullb_group_make_item(struct config_group *group, const char *name)
+{
+ struct nullb_device *dev;
+
+ dev = null_alloc_dev();
+ if (!dev)
+ return ERR_PTR(-ENOMEM);
+
+ config_item_init_type_name(&dev->item, name, &nullb_device_type);
+
+ return &dev->item;
+}
+
+static void
+nullb_group_drop_item(struct config_group *group, struct config_item *item)
+{
+ config_item_put(item);
+}
+
+static ssize_t memb_group_features_show(struct config_item *item, char *page)
+{
+ return snprintf(page, PAGE_SIZE, "\n");
+}
+
+CONFIGFS_ATTR_RO(memb_group_, features);
+
+static struct configfs_attribute *nullb_group_attrs[] = {
+ &memb_group_attr_features,
+ NULL,
+};
+
+static struct configfs_group_operations nullb_group_ops = {
+ .make_item = nullb_group_make_item,
+ .drop_item = nullb_group_drop_item,
+};
+
+static struct config_item_type nullb_group_type = {
+ .ct_group_ops = &nullb_group_ops,
+ .ct_attrs = nullb_group_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+static struct configfs_subsystem nullb_subsys = {
+ .su_group = {
+ .cg_item = {
+ .ci_namebuf = "nullb",
+ .ci_type = &nullb_group_type,
+ },
+ },
+};
+
static struct nullb_device *null_alloc_dev(void)
{
struct nullb_device *dev;
@@ -919,12 +1116,19 @@ static int __init null_init(void)
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;
+
mutex_init(&lock);
null_major = register_blkdev(0, "nullb");
if (null_major < 0) {
ret = null_major;
- goto err_tagset;
+ goto err_conf;
}
if (g_use_lightnvm) {
@@ -961,6 +1165,8 @@ static int __init null_init(void)
kmem_cache_destroy(ppa_cache);
err_ppa:
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);
@@ -971,6 +1177,8 @@ static void __exit null_exit(void)
{
struct nullb *nullb;
+ configfs_unregister_subsystem(&nullb_subsys);
+
unregister_blkdev(null_major, "nullb");
mutex_lock(&lock);
--
2.9.5
