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nullb: add configfs interface
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@fb.com> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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2 changed files with 210 additions and 1 deletions
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@ -17,6 +17,7 @@ if BLK_DEV
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config BLK_DEV_NULL_BLK
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config BLK_DEV_NULL_BLK
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tristate "Null test block driver"
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tristate "Null test block driver"
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depends on CONFIGFS_FS
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config BLK_DEV_FD
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config BLK_DEV_FD
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tristate "Normal floppy disk support"
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tristate "Normal floppy disk support"
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@ -1,3 +1,7 @@
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/*
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* Add configfs and memory store: Kyungchan Koh <kkc6196@fb.com> and
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* Shaohua Li <shli@fb.com>
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*/
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#include <linux/module.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/moduleparam.h>
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@ -9,6 +13,7 @@
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#include <linux/blk-mq.h>
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#include <linux/blk-mq.h>
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#include <linux/hrtimer.h>
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#include <linux/hrtimer.h>
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#include <linux/lightnvm.h>
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#include <linux/lightnvm.h>
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#include <linux/configfs.h>
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struct nullb_cmd {
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struct nullb_cmd {
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struct list_head list;
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struct list_head list;
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@ -30,8 +35,21 @@ struct nullb_queue {
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struct nullb_cmd *cmds;
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struct nullb_cmd *cmds;
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};
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};
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/*
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* Status flags for nullb_device.
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*
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* CONFIGURED: Device has been configured and turned on. Cannot reconfigure.
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* UP: Device is currently on and visible in userspace.
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*/
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enum nullb_device_flags {
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NULLB_DEV_FL_CONFIGURED = 0,
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NULLB_DEV_FL_UP = 1,
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};
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struct nullb_device {
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struct nullb_device {
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struct nullb *nullb;
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struct nullb *nullb;
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struct config_item item;
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unsigned long flags; /* device flags */
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unsigned long size; /* device size in MB */
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unsigned long size; /* device size in MB */
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unsigned long completion_nsec; /* time in ns to complete a request */
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unsigned long completion_nsec; /* time in ns to complete a request */
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@ -173,6 +191,185 @@ static bool g_use_per_node_hctx;
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module_param_named(use_per_node_hctx, g_use_per_node_hctx, bool, S_IRUGO);
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module_param_named(use_per_node_hctx, g_use_per_node_hctx, bool, S_IRUGO);
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MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false");
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MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false");
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static struct nullb_device *null_alloc_dev(void);
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static void null_free_dev(struct nullb_device *dev);
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static inline struct nullb_device *to_nullb_device(struct config_item *item)
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{
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return item ? container_of(item, struct nullb_device, item) : NULL;
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}
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static inline ssize_t nullb_device_uint_attr_show(unsigned int val, char *page)
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{
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return snprintf(page, PAGE_SIZE, "%u\n", val);
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}
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static inline ssize_t nullb_device_ulong_attr_show(unsigned long val,
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char *page)
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{
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return snprintf(page, PAGE_SIZE, "%lu\n", val);
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}
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static inline ssize_t nullb_device_bool_attr_show(bool val, char *page)
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{
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return snprintf(page, PAGE_SIZE, "%u\n", val);
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}
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static ssize_t nullb_device_uint_attr_store(unsigned int *val,
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const char *page, size_t count)
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{
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unsigned int tmp;
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int result;
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result = kstrtouint(page, 0, &tmp);
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if (result)
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return result;
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*val = tmp;
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return count;
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}
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static ssize_t nullb_device_ulong_attr_store(unsigned long *val,
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const char *page, size_t count)
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{
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int result;
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unsigned long tmp;
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result = kstrtoul(page, 0, &tmp);
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if (result)
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return result;
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*val = tmp;
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return count;
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}
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static ssize_t nullb_device_bool_attr_store(bool *val, const char *page,
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size_t count)
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{
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bool tmp;
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int result;
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result = kstrtobool(page, &tmp);
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if (result)
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return result;
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*val = tmp;
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return count;
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}
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/* The following macro should only be used with TYPE = {uint, ulong, bool}. */
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#define NULLB_DEVICE_ATTR(NAME, TYPE) \
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static ssize_t \
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nullb_device_##NAME##_show(struct config_item *item, char *page) \
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{ \
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return nullb_device_##TYPE##_attr_show( \
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to_nullb_device(item)->NAME, page); \
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} \
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static ssize_t \
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nullb_device_##NAME##_store(struct config_item *item, const char *page, \
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size_t count) \
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{ \
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if (test_bit(NULLB_DEV_FL_CONFIGURED, &to_nullb_device(item)->flags)) \
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return -EBUSY; \
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return nullb_device_##TYPE##_attr_store( \
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&to_nullb_device(item)->NAME, page, count); \
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} \
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CONFIGFS_ATTR(nullb_device_, NAME);
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NULLB_DEVICE_ATTR(size, ulong);
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NULLB_DEVICE_ATTR(completion_nsec, ulong);
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NULLB_DEVICE_ATTR(submit_queues, uint);
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NULLB_DEVICE_ATTR(home_node, uint);
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NULLB_DEVICE_ATTR(queue_mode, uint);
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NULLB_DEVICE_ATTR(blocksize, uint);
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NULLB_DEVICE_ATTR(irqmode, uint);
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NULLB_DEVICE_ATTR(hw_queue_depth, uint);
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NULLB_DEVICE_ATTR(use_lightnvm, bool);
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NULLB_DEVICE_ATTR(blocking, bool);
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NULLB_DEVICE_ATTR(use_per_node_hctx, bool);
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static struct configfs_attribute *nullb_device_attrs[] = {
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&nullb_device_attr_size,
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&nullb_device_attr_completion_nsec,
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&nullb_device_attr_submit_queues,
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&nullb_device_attr_home_node,
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&nullb_device_attr_queue_mode,
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&nullb_device_attr_blocksize,
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&nullb_device_attr_irqmode,
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&nullb_device_attr_hw_queue_depth,
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&nullb_device_attr_use_lightnvm,
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&nullb_device_attr_blocking,
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&nullb_device_attr_use_per_node_hctx,
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NULL,
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};
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static void nullb_device_release(struct config_item *item)
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{
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null_free_dev(to_nullb_device(item));
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}
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static struct configfs_item_operations nullb_device_ops = {
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.release = nullb_device_release,
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};
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static struct config_item_type nullb_device_type = {
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.ct_item_ops = &nullb_device_ops,
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.ct_attrs = nullb_device_attrs,
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.ct_owner = THIS_MODULE,
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};
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static struct
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config_item *nullb_group_make_item(struct config_group *group, const char *name)
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{
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struct nullb_device *dev;
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dev = null_alloc_dev();
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if (!dev)
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return ERR_PTR(-ENOMEM);
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config_item_init_type_name(&dev->item, name, &nullb_device_type);
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return &dev->item;
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}
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static void
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nullb_group_drop_item(struct config_group *group, struct config_item *item)
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{
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config_item_put(item);
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}
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static ssize_t memb_group_features_show(struct config_item *item, char *page)
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{
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return snprintf(page, PAGE_SIZE, "\n");
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}
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CONFIGFS_ATTR_RO(memb_group_, features);
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static struct configfs_attribute *nullb_group_attrs[] = {
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&memb_group_attr_features,
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NULL,
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};
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static struct configfs_group_operations nullb_group_ops = {
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.make_item = nullb_group_make_item,
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.drop_item = nullb_group_drop_item,
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};
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static struct config_item_type nullb_group_type = {
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.ct_group_ops = &nullb_group_ops,
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.ct_attrs = nullb_group_attrs,
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.ct_owner = THIS_MODULE,
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};
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static struct configfs_subsystem nullb_subsys = {
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.su_group = {
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.cg_item = {
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.ci_namebuf = "nullb",
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.ci_type = &nullb_group_type,
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},
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},
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};
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static struct nullb_device *null_alloc_dev(void)
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static struct nullb_device *null_alloc_dev(void)
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{
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{
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struct nullb_device *dev;
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struct nullb_device *dev;
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@ -919,12 +1116,19 @@ static int __init null_init(void)
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return ret;
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return ret;
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}
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}
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config_group_init(&nullb_subsys.su_group);
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mutex_init(&nullb_subsys.su_mutex);
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ret = configfs_register_subsystem(&nullb_subsys);
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if (ret)
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goto err_tagset;
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mutex_init(&lock);
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mutex_init(&lock);
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null_major = register_blkdev(0, "nullb");
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null_major = register_blkdev(0, "nullb");
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if (null_major < 0) {
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if (null_major < 0) {
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ret = null_major;
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ret = null_major;
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goto err_tagset;
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goto err_conf;
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}
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}
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if (g_use_lightnvm) {
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if (g_use_lightnvm) {
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@ -961,6 +1165,8 @@ static int __init null_init(void)
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kmem_cache_destroy(ppa_cache);
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kmem_cache_destroy(ppa_cache);
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err_ppa:
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err_ppa:
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unregister_blkdev(null_major, "nullb");
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unregister_blkdev(null_major, "nullb");
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err_conf:
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configfs_unregister_subsystem(&nullb_subsys);
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err_tagset:
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err_tagset:
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if (g_queue_mode == NULL_Q_MQ && shared_tags)
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if (g_queue_mode == NULL_Q_MQ && shared_tags)
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blk_mq_free_tag_set(&tag_set);
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blk_mq_free_tag_set(&tag_set);
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@ -971,6 +1177,8 @@ static void __exit null_exit(void)
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{
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{
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struct nullb *nullb;
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struct nullb *nullb;
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configfs_unregister_subsystem(&nullb_subsys);
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unregister_blkdev(null_major, "nullb");
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unregister_blkdev(null_major, "nullb");
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mutex_lock(&lock);
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mutex_lock(&lock);
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