[PATCH 4/4] nvme: enable char device per namespace

javier
2020-12-01T12:57:36Z

From: Javier González <javier.gonz@samsung.com>

Create a char device per NVMe namespace. This char device is always
initialized, independently of whether thedeatures implemented by the
device are supported by the kernel. User-space can therefore always
issue IOCTLs to the NVMe driver using this char device.

The char device is presented as /dev/nvmeXcYnZ to follow the hidden
block device. This naming also aligns with nvme-cli filters, so the char
device should be usable without tool changes.

Signed-off-by: Javier González <javier.gonz@samsung.com>
---
drivers/nvme/host/core.c | 144 +++++++++++++++++++++++++++++++++++----
drivers/nvme/host/nvme.h | 3 +
2 files changed, 132 insertions(+), 15 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 2c23ea6dc296..9c4acf2725f3 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -86,7 +86,9 @@ static DEFINE_MUTEX(nvme_subsystems_lock);

static DEFINE_IDA(nvme_instance_ida);
static dev_t nvme_ctrl_base_chr_devt;
+static dev_t nvme_ns_base_chr_devt;
static struct class *nvme_class;
+static struct class *nvme_ns_class;
static struct class *nvme_subsys_class;

static void nvme_put_subsystem(struct nvme_subsystem *subsys);
@@ -497,6 +499,7 @@ static void nvme_free_ns(struct kref *kref)
if (ns->ndev)
nvme_nvm_unregister(ns);

+ cdev_device_del(&ns->cdev, &ns->cdev_device);
put_disk(ns->disk);
nvme_put_ns_head(ns->head);
nvme_put_ctrl(ns->ctrl);
@@ -1696,15 +1699,15 @@ static int nvme_handle_ctrl_ioctl(struct nvme_ns *ns, unsigned int cmd,
return ret;
}

-static int nvme_ioctl(struct block_device *bdev, fmode_t mode,
- unsigned int cmd, unsigned long arg)
+static int __nvme_ns_ioctl(struct gendisk *disk, unsigned int cmd,
+ unsigned long arg)
{
struct nvme_ns_head *head = NULL;
void __user *argp = (void __user *)arg;
struct nvme_ns *ns;
int srcu_idx, ret;

- ns = nvme_get_ns_from_disk(bdev->bd_disk, &head, &srcu_idx);
+ ns = nvme_get_ns_from_disk(disk, &head, &srcu_idx);
if (unlikely(!ns))
return -EWOULDBLOCK;

@@ -1741,6 +1744,18 @@ static int nvme_ioctl(struct block_device *bdev, fmode_t mode,
return ret;
}

+static int nvme_ioctl(struct block_device *bdev, fmode_t mode,
+ unsigned int cmd, unsigned long arg)
+{
+ return __nvme_ns_ioctl(bdev->bd_disk, cmd, arg);
+}
+
+static long nvme_cdev_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ return __nvme_ns_ioctl((struct gendisk *)file->private_data, cmd, arg);
+}
+
#ifdef CONFIG_COMPAT
struct nvme_user_io32 {
__u8 opcode;
@@ -1782,10 +1797,8 @@ static int nvme_compat_ioctl(struct block_device *bdev, fmode_t mode,
#define nvme_compat_ioctl NULL
#endif /* CONFIG_COMPAT */

-static int nvme_open(struct block_device *bdev, fmode_t mode)
+static int __nvme_open(struct nvme_ns *ns)
{
- struct nvme_ns *ns = bdev->bd_disk->private_data;
-
#ifdef CONFIG_NVME_MULTIPATH
/* should never be called due to GENHD_FL_HIDDEN */
if (WARN_ON_ONCE(ns->head->disk))
@@ -1804,12 +1817,24 @@ static int nvme_open(struct block_device *bdev, fmode_t mode)
return -ENXIO;
}

+static void __nvme_release(struct nvme_ns *ns)
+{
+ module_put(ns->ctrl->ops->module);
+ nvme_put_ns(ns);
+}
+
+static int nvme_open(struct block_device *bdev, fmode_t mode)
+{
+ struct nvme_ns *ns = bdev->bd_disk->private_data;
+
+ return __nvme_open(ns);
+}
+
static void nvme_release(struct gendisk *disk, fmode_t mode)
{
struct nvme_ns *ns = disk->private_data;

- module_put(ns->ctrl->ops->module);
- nvme_put_ns(ns);
+ __nvme_release(ns);
}

static int nvme_getgeo(struct block_device *bdev, struct hd_geometry *geo)
@@ -1821,6 +1846,26 @@ static int nvme_getgeo(struct block_device *bdev, struct hd_geometry *geo)
return 0;
}

+static int nvme_cdev_open(struct inode *inode, struct file *file)
+{
+ struct nvme_ns *ns = container_of(inode->i_cdev, struct nvme_ns, cdev);
+ int ret;
+
+ ret = __nvme_open(ns);
+ if (!ret)
+ file->private_data = ns->disk;
+
+ return ret;
+}
+
+static int nvme_cdev_release(struct inode *inode, struct file *file)
+{
+ struct nvme_ns *ns = container_of(inode->i_cdev, struct nvme_ns, cdev);
+
+ __nvme_release(ns);
+ return 0;
+}
+
#ifdef CONFIG_BLK_DEV_INTEGRITY
static void nvme_init_integrity(struct gendisk *disk, u16 ms, u8 pi_type,
u32 max_integrity_segments)
@@ -2303,6 +2348,14 @@ static const struct block_device_operations nvme_bdev_ops = {
.pr_ops = &nvme_pr_ops,
};

+static const struct file_operations nvme_cdev_fops = {
+ .owner = THIS_MODULE,
+ .open = nvme_cdev_open,
+ .release = nvme_cdev_release,
+ .unlocked_ioctl = nvme_cdev_ioctl,
+ .compat_ioctl = compat_ptr_ioctl,
+};
+
#ifdef CONFIG_NVME_MULTIPATH
static int nvme_ns_head_open(struct block_device *bdev, fmode_t mode)
{
@@ -3301,6 +3354,9 @@ static inline struct nvme_ns_head *dev_to_ns_head(struct device *dev)
{
struct gendisk *disk = dev_to_disk(dev);

+ if (dev->class == nvme_ns_class)
+ return ((struct nvme_ns *)dev_get_drvdata(dev))->head;
+
if (disk->fops == &nvme_bdev_ops)
return nvme_get_ns_from_dev(dev)->head;
else
@@ -3390,7 +3446,7 @@ static struct attribute *nvme_ns_id_attrs[] = {
};

static umode_t nvme_ns_id_attrs_are_visible(struct kobject *kobj,
- struct attribute *a, int n)
+ struct attribute *a, int n)
{
struct device *dev = container_of(kobj, struct device, kobj);
struct nvme_ns_ids *ids = &dev_to_ns_head(dev)->ids;
@@ -3432,6 +3488,11 @@ const struct attribute_group *nvme_ns_id_attr_groups[] = {
NULL,
};

+const struct attribute_group *nvme_ns_char_id_attr_groups[] = {
+ &nvme_ns_id_attr_group,
+ NULL,
+};
+
#define nvme_show_str_function(field) \
static ssize_t field##_show(struct device *dev, \
struct device_attribute *attr, char *buf) \
@@ -3824,6 +3885,36 @@ struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid)
}
EXPORT_SYMBOL_NS_GPL(nvme_find_get_ns, NVME_TARGET_PASSTHRU);

+static int nvme_alloc_chardev_ns(struct nvme_ctrl *ctrl, struct nvme_ns *ns)
+{
+ char cdisk_name[DISK_NAME_LEN];
+ int ret = 0;
+
+ device_initialize(&ns->cdev_device);
+ ns->cdev_device.devt = MKDEV(MAJOR(nvme_ns_base_chr_devt),
+ ns->head->instance);
+ ns->cdev_device.class = nvme_ns_class;
+ ns->cdev_device.parent = ctrl->device;
+ ns->cdev_device.groups = nvme_ns_char_id_attr_groups;
+ dev_set_drvdata(&ns->cdev_device, ns);
+
+ sprintf(cdisk_name, "nvme%dc%dn%d", ctrl->subsys->instance,
+ ctrl->instance, ns->head->instance);
+
+ ret = dev_set_name(&ns->cdev_device, "%s", cdisk_name);
+ if (ret)
+ return ret;
+
+ cdev_init(&ns->cdev, &nvme_cdev_fops);
+ ns->cdev.owner = ctrl->ops->module;
+
+ ret = cdev_device_add(&ns->cdev, &ns->cdev_device);
+ if (ret)
+ kfree_const(ns->cdev_device.kobj.name);
+
+ return ret;
+}
+
static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid,
struct nvme_ns_ids *ids)
{
@@ -3870,8 +3961,12 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid,
memcpy(disk->disk_name, disk_name, DISK_NAME_LEN);
ns->disk = disk;

+ /* When the device does not support any of the features required by the
+ * kernel (or viceversa), hide the block device. We can still rely on
+ * the namespace char device for submitting IOCTLs
+ */
if (nvme_update_ns_info(ns, id))
- goto out_put_disk;
+ disk->flags |= GENHD_FL_HIDDEN;

if ((ctrl->quirks & NVME_QUIRK_LIGHTNVM) && id->vs[0] == 0x1) {
if (nvme_nvm_register(ns, disk_name, node)) {
@@ -3887,9 +3982,12 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid,
nvme_get_ctrl(ctrl);

device_add_disk(ctrl->device, ns->disk, nvme_ns_id_attr_groups);
-
nvme_mpath_add_disk(ns, id);
nvme_fault_inject_init(&ns->fault_inject, ns->disk->disk_name);
+
+ if (nvme_alloc_chardev_ns(ctrl, ns))
+ goto out_put_disk;
+
kfree(id);

return;
@@ -4685,23 +4783,38 @@ static int __init nvme_core_init(void)
if (result < 0)
goto destroy_delete_wq;

+ result = alloc_chrdev_region(&nvme_ns_base_chr_devt, 0,
+ NVME_MINORS, "nvmec");
+ if (result < 0)
+ goto unregister_dev_chrdev;
+
nvme_class = class_create(THIS_MODULE, "nvme");
if (IS_ERR(nvme_class)) {
result = PTR_ERR(nvme_class);
- goto unregister_chrdev;
+ goto unregister_ns_chrdev;
}
nvme_class->dev_uevent = nvme_class_uevent;

+ nvme_ns_class = class_create(THIS_MODULE, "nvme-ns");
+ if (IS_ERR(nvme_ns_class)) {
+ result = PTR_ERR(nvme_ns_class);
+ goto destroy_dev_class;
+ }
+
nvme_subsys_class = class_create(THIS_MODULE, "nvme-subsystem");
if (IS_ERR(nvme_subsys_class)) {
result = PTR_ERR(nvme_subsys_class);
- goto destroy_class;
+ goto destroy_ns_class;
}
return 0;

-destroy_class:
+destroy_ns_class:
+ class_destroy(nvme_ns_class);
+destroy_dev_class:
class_destroy(nvme_class);
-unregister_chrdev:
+unregister_ns_chrdev:
+ unregister_chrdev_region(nvme_ns_base_chr_devt, NVME_MINORS);
+unregister_dev_chrdev:
unregister_chrdev_region(nvme_ctrl_base_chr_devt, NVME_MINORS);
destroy_delete_wq:
destroy_workqueue(nvme_delete_wq);
@@ -4717,6 +4830,7 @@ static void __exit nvme_core_exit(void)
{
class_destroy(nvme_subsys_class);
class_destroy(nvme_class);
+ unregister_chrdev_region(nvme_ns_base_chr_devt, NVME_MINORS);
unregister_chrdev_region(nvme_ctrl_base_chr_devt, NVME_MINORS);
destroy_workqueue(nvme_delete_wq);
destroy_workqueue(nvme_reset_wq);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index cdfce7250da0..533bd54f9194 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -436,6 +436,9 @@ struct nvme_ns {
struct kref kref;
struct nvme_ns_head *head;

+ struct device cdev_device; /* char device */
+ struct cdev cdev;
+
int lba_shift;
u16 ms;
u16 sgs;
--
2.17.1