[PATCH V4] nvme: enable char device per namespace

[PATCH V4] nvme: enable char device per namespace

[javier]

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

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

The char device is presented as /dev/generic-nvmeXcYnZ. This naming
scheme follows the convention of the hidden device (nvmeXcYnZ). Support
for multipath will follow.

Keith: Regarding nvme-cli support, should the generic handle show up in
place such as 'nvme list'? If so, I can send a patch for the filters.

Changes since V3 (merged patch from keith)
  - Use a dedicated ida for the generic handle
  - Do not abort namespace greation if the generic handle fails

Changes since V2:
  - Apply a number of naming and code structure improvements (from
    Christoph)
  - Use i_cdev to pull struct nvme_ns in the ioctl path instead of
    populating file->private_data (from Christoph)
  - Change char device and sysfs entries to /dev/generic-nvmeXcYnZ to
    follow the hidden device naming scheme (from Christoph and Keith)

Changes since V1:
  - Remove patches 1-3 which are already picked up by Christoph
  - Change the char device and sysfs entries to nvmeXnYc / c signals
    char device
  - Address Minwoo's comments on inline functions and style

Signed-off-by: Javier González <javier.gonz@samsung.com>
---
 drivers/nvme/host/core.c | 159 +++++++++++++++++++++++++++++++++++----
 drivers/nvme/host/nvme.h |   9 +++
 2 files changed, 152 insertions(+), 16 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 99f91efe3824..d1ee462f41fa 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -86,7 +86,11 @@ static DEFINE_MUTEX(nvme_subsystems_lock);
 
 static DEFINE_IDA(nvme_instance_ida);
 static dev_t nvme_ctrl_base_chr_devt;
+
+static DEFINE_IDA(nvme_gen_minor_ida);
+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);
@@ -537,7 +541,10 @@ static void nvme_free_ns(struct kref *kref)
 
 	if (ns->ndev)
 		nvme_nvm_unregister(ns);
+	if (ns->minor)
+		ida_simple_remove(&nvme_gen_minor_ida, ns->minor - 1);
 
+	cdev_device_del(&ns->cdev, &ns->cdev_device);
 	put_disk(ns->disk);
 	nvme_put_ns_head(ns->head);
 	nvme_put_ctrl(ns->ctrl);
@@ -1738,15 +1745,15 @@ 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_disk_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;
 
@@ -1783,6 +1790,12 @@ 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_disk_ioctl(bdev->bd_disk, cmd, arg);
+}
+
 #ifdef CONFIG_COMPAT
 struct nvme_user_io32 {
 	__u8	opcode;
@@ -1824,10 +1837,8 @@ 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_ns_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))
@@ -1846,14 +1857,22 @@ static int nvme_open(struct block_device *bdev, fmode_t mode)
 	return -ENXIO;
 }
 
-static void nvme_release(struct gendisk *disk, fmode_t mode)
+static void nvme_ns_release(struct nvme_ns *ns)
 {
-	struct nvme_ns *ns = disk->private_data;
-
 	module_put(ns->ctrl->ops->module);
 	nvme_put_ns(ns);
 }
 
+static int nvme_open(struct block_device *bdev, fmode_t mode)
+{
+	return nvme_ns_open(bdev->bd_disk->private_data);
+}
+
+static void nvme_release(struct gendisk *disk, fmode_t mode)
+{
+	nvme_ns_release(disk->private_data);
+}
+
 static int nvme_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {
 	/* some standard values */
@@ -2209,6 +2228,13 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
 	return 0;
 
 out_unfreeze:
+	/*
+	 * 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
+	 */
+	ns->disk->flags |= GENHD_FL_HIDDEN;
+
 	blk_mq_unfreeze_queue(ns->disk->queue);
 	return ret;
 }
@@ -2346,6 +2372,38 @@ static const struct block_device_operations nvme_bdev_ops = {
 	.pr_ops		= &nvme_pr_ops,
 };
 
+static int nvme_cdev_open(struct inode *inode, struct file *file)
+{
+	struct nvme_ns *ns = container_of(inode->i_cdev, struct nvme_ns, cdev);
+
+	return nvme_ns_open(ns);
+}
+
+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_ns_release(ns);
+	return 0;
+}
+
+static long nvme_cdev_ioctl(struct file *file, unsigned int cmd,
+			    unsigned long arg)
+{
+	struct nvme_ns *ns = container_of(file->f_inode->i_cdev,
+				struct nvme_ns, cdev);
+
+	return nvme_disk_ioctl(ns->disk, cmd, arg);
+}
+
+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)
 {
@@ -3343,6 +3401,9 @@ 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 nvme_get_ns_from_cdev(dev)->head;
+
 	if (disk->fops == &nvme_bdev_ops)
 		return nvme_get_ns_from_dev(dev)->head;
 	else
@@ -3474,6 +3535,11 @@ 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)		\
@@ -3866,6 +3932,47 @@ 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;
+
+	ret = ida_simple_get(&nvme_gen_minor_ida, 0, 0, GFP_KERNEL);
+	if (ret < 0)
+		return ret;
+
+	ns->minor = ret + 1;
+	device_initialize(&ns->cdev_device);
+	ns->cdev_device.devt = MKDEV(MAJOR(nvme_ns_base_chr_devt), ret);
+	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-generic-%dc%dn%d", ctrl->subsys->instance,
+		ctrl->instance, ns->head->instance);
+
+	ret = dev_set_name(&ns->cdev_device, "%s", cdisk_name);
+	if (ret)
+		goto put_ida;
+
+	cdev_init(&ns->cdev, &nvme_cdev_fops);
+	ns->cdev.owner = ctrl->ops->module;
+
+	ret = cdev_device_add(&ns->cdev, &ns->cdev_device);
+	if (ret)
+		goto free_kobj;
+
+	return ret;
+
+free_kobj:
+	kfree_const(ns->cdev_device.kobj.name);
+put_ida:
+	ida_simple_remove(&nvme_gen_minor_ida, ns->minor - 1);
+	ns->minor = 0;
+	return ret;
+}
+
 static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid,
 		struct nvme_ns_ids *ids)
 {
@@ -3912,8 +4019,7 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid,
 	memcpy(disk->disk_name, disk_name, DISK_NAME_LEN);
 	ns->disk = disk;
 
-	if (nvme_update_ns_info(ns, id))
-		goto out_put_disk;
+	nvme_update_ns_info(ns, id);
 
 	if ((ctrl->quirks & NVME_QUIRK_LIGHTNVM) && id->vs[0] == 0x1) {
 		if (nvme_nvm_register(ns, disk_name, node)) {
@@ -3929,9 +4035,14 @@ 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))
+		dev_warn(ctrl->device,
+			"failed to create generic handle for nsid:%d\n",
+			nsid);
+
 	kfree(id);
 
 	return;
@@ -4733,23 +4844,38 @@ 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);
@@ -4765,6 +4891,7 @@ 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 bfcedfa4b057..1e52f7da82de 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -439,6 +439,10 @@ struct nvme_ns {
 	struct kref kref;
 	struct nvme_ns_head *head;
 
+	struct device cdev_device;	/* char device */
+	struct cdev cdev;
+	int minor;
+
 	int lba_shift;
 	u16 ms;
 	u16 sgs;
@@ -818,6 +822,11 @@ static inline struct nvme_ns *nvme_get_ns_from_dev(struct device *dev)
 	return dev_to_disk(dev)->private_data;
 }
 
+static inline struct nvme_ns *nvme_get_ns_from_cdev(struct device *dev)
+{
+	return dev_get_drvdata(dev);
+}
+
 #ifdef CONFIG_NVME_HWMON
 int nvme_hwmon_init(struct nvme_ctrl *ctrl);
 #else
-- 
2.17.1


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Re: nvme: enable char device per namespace

[Javier González]

On 16.12.2020 19:18, javier@javigon.com wrote:
>From: Javier González <javier.gonz@samsung.com>
>
>Create a char device per NVMe namespace. This char device is always
>initialized, independently of whether the features implemented by the
>device are supported by the kernel. User-space can therefore always
>issue IOCTLs to the NVMe driver using the char device.
>
>The char device is presented as /dev/generic-nvmeXcYnZ. This naming
>scheme follows the convention of the hidden device (nvmeXcYnZ). Support
>for multipath will follow.
>
>Keith: Regarding nvme-cli support, should the generic handle show up in
>place such as 'nvme list'? If so, I can send a patch for the filters.
>
>Changes since V3 (merged patch from keith)
>  - Use a dedicated ida for the generic handle
>  - Do not abort namespace greation if the generic handle fails
>
>Changes since V2:
>  - Apply a number of naming and code structure improvements (from
>    Christoph)
>  - Use i_cdev to pull struct nvme_ns in the ioctl path instead of
>    populating file->private_data (from Christoph)
>  - Change char device and sysfs entries to /dev/generic-nvmeXcYnZ to
>    follow the hidden device naming scheme (from Christoph and Keith)
>
>Changes since V1:
>  - Remove patches 1-3 which are already picked up by Christoph
>  - Change the char device and sysfs entries to nvmeXnYc / c signals
>    char device
>  - Address Minwoo's comments on inline functions and style
>
>Signed-off-by: Javier González <javier.gonz@samsung.com>
>---
> drivers/nvme/host/core.c | 159 +++++++++++++++++++++++++++++++++++----
> drivers/nvme/host/nvme.h |   9 +++
> 2 files changed, 152 insertions(+), 16 deletions(-)
>
>diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>index 99f91efe3824..d1ee462f41fa 100644
>--- a/drivers/nvme/host/core.c
>+++ b/drivers/nvme/host/core.c
>@@ -86,7 +86,11 @@ static DEFINE_MUTEX(nvme_subsystems_lock);
>
> static DEFINE_IDA(nvme_instance_ida);
> static dev_t nvme_ctrl_base_chr_devt;
>+
>+static DEFINE_IDA(nvme_gen_minor_ida);
>+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);
>@@ -537,7 +541,10 @@ static void nvme_free_ns(struct kref *kref)
>
> 	if (ns->ndev)
> 		nvme_nvm_unregister(ns);
>+	if (ns->minor)
>+		ida_simple_remove(&nvme_gen_minor_ida, ns->minor - 1);
>
>+	cdev_device_del(&ns->cdev, &ns->cdev_device);
> 	put_disk(ns->disk);
> 	nvme_put_ns_head(ns->head);
> 	nvme_put_ctrl(ns->ctrl);
>@@ -1738,15 +1745,15 @@ 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_disk_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;
>
>@@ -1783,6 +1790,12 @@ 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_disk_ioctl(bdev->bd_disk, cmd, arg);
>+}
>+
> #ifdef CONFIG_COMPAT
> struct nvme_user_io32 {
> 	__u8	opcode;
>@@ -1824,10 +1837,8 @@ 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_ns_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))
>@@ -1846,14 +1857,22 @@ static int nvme_open(struct block_device *bdev, fmode_t mode)
> 	return -ENXIO;
> }
>
>-static void nvme_release(struct gendisk *disk, fmode_t mode)
>+static void nvme_ns_release(struct nvme_ns *ns)
> {
>-	struct nvme_ns *ns = disk->private_data;
>-
> 	module_put(ns->ctrl->ops->module);
> 	nvme_put_ns(ns);
> }
>
>+static int nvme_open(struct block_device *bdev, fmode_t mode)
>+{
>+	return nvme_ns_open(bdev->bd_disk->private_data);
>+}
>+
>+static void nvme_release(struct gendisk *disk, fmode_t mode)
>+{
>+	nvme_ns_release(disk->private_data);
>+}
>+
> static int nvme_getgeo(struct block_device *bdev, struct hd_geometry *geo)
> {
> 	/* some standard values */
>@@ -2209,6 +2228,13 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
> 	return 0;
>
> out_unfreeze:
>+	/*
>+	 * 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
>+	 */
>+	ns->disk->flags |= GENHD_FL_HIDDEN;
>+
> 	blk_mq_unfreeze_queue(ns->disk->queue);
> 	return ret;
> }
>@@ -2346,6 +2372,38 @@ static const struct block_device_operations nvme_bdev_ops = {
> 	.pr_ops		= &nvme_pr_ops,
> };
>
>+static int nvme_cdev_open(struct inode *inode, struct file *file)
>+{
>+	struct nvme_ns *ns = container_of(inode->i_cdev, struct nvme_ns, cdev);
>+
>+	return nvme_ns_open(ns);
>+}
>+
>+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_ns_release(ns);
>+	return 0;
>+}
>+
>+static long nvme_cdev_ioctl(struct file *file, unsigned int cmd,
>+			    unsigned long arg)
>+{
>+	struct nvme_ns *ns = container_of(file->f_inode->i_cdev,
>+				struct nvme_ns, cdev);
>+
>+	return nvme_disk_ioctl(ns->disk, cmd, arg);
>+}
>+
>+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)
> {
>@@ -3343,6 +3401,9 @@ 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 nvme_get_ns_from_cdev(dev)->head;
>+
> 	if (disk->fops == &nvme_bdev_ops)
> 		return nvme_get_ns_from_dev(dev)->head;
> 	else
>@@ -3474,6 +3535,11 @@ 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)		\
>@@ -3866,6 +3932,47 @@ 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;
>+
>+	ret = ida_simple_get(&nvme_gen_minor_ida, 0, 0, GFP_KERNEL);
>+	if (ret < 0)
>+		return ret;
>+
>+	ns->minor = ret + 1;
>+	device_initialize(&ns->cdev_device);
>+	ns->cdev_device.devt = MKDEV(MAJOR(nvme_ns_base_chr_devt), ret);
>+	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-generic-%dc%dn%d", ctrl->subsys->instance,
>+		ctrl->instance, ns->head->instance);
>+
>+	ret = dev_set_name(&ns->cdev_device, "%s", cdisk_name);
>+	if (ret)
>+		goto put_ida;
>+
>+	cdev_init(&ns->cdev, &nvme_cdev_fops);
>+	ns->cdev.owner = ctrl->ops->module;
>+
>+	ret = cdev_device_add(&ns->cdev, &ns->cdev_device);
>+	if (ret)
>+		goto free_kobj;
>+
>+	return ret;
>+
>+free_kobj:
>+	kfree_const(ns->cdev_device.kobj.name);
>+put_ida:
>+	ida_simple_remove(&nvme_gen_minor_ida, ns->minor - 1);
>+	ns->minor = 0;
>+	return ret;
>+}
>+
> static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid,
> 		struct nvme_ns_ids *ids)
> {
>@@ -3912,8 +4019,7 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid,
> 	memcpy(disk->disk_name, disk_name, DISK_NAME_LEN);
> 	ns->disk = disk;
>
>-	if (nvme_update_ns_info(ns, id))
>-		goto out_put_disk;
>+	nvme_update_ns_info(ns, id);
>
> 	if ((ctrl->quirks & NVME_QUIRK_LIGHTNVM) && id->vs[0] == 0x1) {
> 		if (nvme_nvm_register(ns, disk_name, node)) {
>@@ -3929,9 +4035,14 @@ 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))
>+		dev_warn(ctrl->device,
>+			"failed to create generic handle for nsid:%d\n",
>+			nsid);
>+
> 	kfree(id);
>
> 	return;
>@@ -4733,23 +4844,38 @@ 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);
>@@ -4765,6 +4891,7 @@ 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 bfcedfa4b057..1e52f7da82de 100644
>--- a/drivers/nvme/host/nvme.h
>+++ b/drivers/nvme/host/nvme.h
>@@ -439,6 +439,10 @@ struct nvme_ns {
> 	struct kref kref;
> 	struct nvme_ns_head *head;
>
>+	struct device cdev_device;	/* char device */
>+	struct cdev cdev;
>+	int minor;
>+
> 	int lba_shift;
> 	u16 ms;
> 	u16 sgs;
>@@ -818,6 +822,11 @@ static inline struct nvme_ns *nvme_get_ns_from_dev(struct device *dev)
> 	return dev_to_disk(dev)->private_data;
> }
>
>+static inline struct nvme_ns *nvme_get_ns_from_cdev(struct device *dev)
>+{
>+	return dev_get_drvdata(dev);
>+}
>+
> #ifdef CONFIG_NVME_HWMON
> int nvme_hwmon_init(struct nvme_ctrl *ctrl);
> #else
>-- 
>2.17.1
>
Christoph, Keith,

Did you have a chance to look into this new version?

Javier

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Re: nvme: enable char device per namespace

[Minwoo Im]

Hello Javier,

I tested this patch based on nvme-5.11:

[    1.219747] BUG: unable to handle page fault for address: 0000000100000041
[    1.220518] #PF: supervisor read access in kernel mode
[    1.220582] #PF: error_code(0x0000) - not-present page
[    1.220582] PGD 0 P4D 0
[    1.220582] Oops: 0000 [#1] SMP PTI
[    1.220582] CPU: 0 PID: 7 Comm: kworker/u16:0 Not tainted 5.11.0-rc1+ #46
[    1.220582] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[    1.220582] Workqueue: nvme-wq nvme_scan_work
[    1.220582] RIP: 0010:nvme_ns_id_attrs_are_visible+0x10f/0x152
[    1.220582] Code: 81 7d d0 80 f9 a1 82 74 0a 48 81 7d d0 a0 f9 a1 82 75 50 48 8b 45 e8 48 89 45 f8 48 8b 45 f8 48 83 e8 60 48 8b 80 60 03 00 00 <48> 8b 40 40 48 3d e0 d1 4d 82 74 07 b8 00 00 00 00 eb 2e 48 8b 45
[    1.220582] RSP: 0000:ffffc90000047b70 EFLAGS: 00010282
[    1.220582] RAX: 0000000100000001 RBX: ffffffff824ddb20 RCX: 0000000000000124
[    1.220582] RDX: ffff8881026eac00 RSI: ffffffff82a1f980 RDI: ffff888102745058
[    1.220582] RBP: ffffc90000047ba8 R08: ffff888102948718 R09: 0000000000000000
[    1.220582] R10: 0000000000000000 R11: ffff888100465080 R12: ffff888102745058
[    1.220582] R13: ffff888102948600 R14: 0000000000000000 R15: ffffffff82a1f548
[    1.220582] FS:  0000000000000000(0000) GS:ffff88842fc00000(0000) knlGS:0000000000000000
[    1.220582] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    1.220582] CR2: 0000000100000041 CR3: 000000000280c001 CR4: 0000000000370ef0
[    1.220582] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    1.220582] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    1.220582] Call Trace:
[    1.220582]  internal_create_group+0xde/0x390
[    1.220582]  internal_create_groups.part.4+0x3e/0xa0
[    1.220582]  device_add+0x3cf/0x830
[    1.220582]  ? cdev_get+0x20/0x20
[    1.220582]  ? cdev_purge+0x60/0x60
[    1.220582]  cdev_device_add+0x44/0x70
[    1.220582]  ? cdev_init+0x50/0x60
[    1.220582]  nvme_alloc_chardev_ns+0x187/0x1eb
[    1.220582]  nvme_alloc_ns+0x367/0x460
[    1.220582]  nvme_validate_or_alloc_ns+0xe2/0x139
[    1.220582]  nvme_scan_ns_list+0x113/0x17a
[    1.220582]  nvme_scan_work+0xa5/0x106
[    1.220582]  process_one_work+0x1dd/0x3e0
[    1.220582]  worker_thread+0x2d/0x3b0
[    1.220582]  ? cancel_delayed_work+0x90/0x90
[    1.220582]  kthread+0x117/0x130
[    1.220582]  ? kthread_park+0x90/0x90
[    1.220582]  ret_from_fork+0x22/0x30
[    1.220582] Modules linked in:
[    1.220582] CR2: 0000000100000041
[    1.220582] ---[ end trace b1f509a1bbfbc113 ]---
[    1.220582] RIP: 0010:nvme_ns_id_attrs_are_visible+0x10f/0x152
[    1.220582] Code: 81 7d d0 80 f9 a1 82 74 0a 48 81 7d d0 a0 f9 a1 82 75 50 48 8b 45 e8 48 89 45 f8 48 8b 45 f8 48 83 e8 60 48 8b 80 60 03 00 00 <48> 8b 40 40 48 3d e0 d1 4d 82 74 07 b8 00 00 00 00 eb 2e 48 8b 45
[    1.220582] RSP: 0000:ffffc90000047b70 EFLAGS: 00010282
[    1.220582] RAX: 0000000100000001 RBX: ffffffff824ddb20 RCX: 0000000000000124
[    1.220582] RDX: ffff8881026eac00 RSI: ffffffff82a1f980 RDI: ffff888102745058
[    1.220582] RBP: ffffc90000047ba8 R08: ffff888102948718 R09: 0000000000000000
[    1.220582] R10: 0000000000000000 R11: ffff888100465080 R12: ffff888102745058
[    1.220582] R13: ffff888102948600 R14: 0000000000000000 R15: ffffffff82a1f548
[    1.220582] FS:  0000000000000000(0000) GS:ffff88842fc00000(0000) knlGS:0000000000000000
[    1.220582] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    1.220582] CR2: 0000000100000041 CR3: 000000000280c001 CR4: 0000000000370ef0
[    1.220582] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    1.220582] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

And this happens when CONFIG_NVME_MULTIPATH=y configured.  Please refere
attached log up there :)

Thanks!

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Re: nvme: enable char device per namespace

[Minwoo Im]

On 21-01-12 18:22:07, Minwoo Im wrote:
> Hello Javier,
> 
> I tested this patch based on nvme-5.11:
> 
> [    1.219747] BUG: unable to handle page fault for address: 0000000100000041
> [    1.220518] #PF: supervisor read access in kernel mode
> [    1.220582] #PF: error_code(0x0000) - not-present page
> [    1.220582] PGD 0 P4D 0
> [    1.220582] Oops: 0000 [#1] SMP PTI
> [    1.220582] CPU: 0 PID: 7 Comm: kworker/u16:0 Not tainted 5.11.0-rc1+ #46
> [    1.220582] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
> [    1.220582] Workqueue: nvme-wq nvme_scan_work
> [    1.220582] RIP: 0010:nvme_ns_id_attrs_are_visible+0x10f/0x152
> [    1.220582] Code: 81 7d d0 80 f9 a1 82 74 0a 48 81 7d d0 a0 f9 a1 82 75 50 48 8b 45 e8 48 89 45 f8 48 8b 45 f8 48 83 e8 60 48 8b 80 60 03 00 00 <48> 8b 40 40 48 3d e0 d1 4d 82 74 07 b8 00 00 00 00 eb 2e 48 8b 45
> [    1.220582] RSP: 0000:ffffc90000047b70 EFLAGS: 00010282
> [    1.220582] RAX: 0000000100000001 RBX: ffffffff824ddb20 RCX: 0000000000000124
> [    1.220582] RDX: ffff8881026eac00 RSI: ffffffff82a1f980 RDI: ffff888102745058
> [    1.220582] RBP: ffffc90000047ba8 R08: ffff888102948718 R09: 0000000000000000
> [    1.220582] R10: 0000000000000000 R11: ffff888100465080 R12: ffff888102745058
> [    1.220582] R13: ffff888102948600 R14: 0000000000000000 R15: ffffffff82a1f548
> [    1.220582] FS:  0000000000000000(0000) GS:ffff88842fc00000(0000) knlGS:0000000000000000
> [    1.220582] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [    1.220582] CR2: 0000000100000041 CR3: 000000000280c001 CR4: 0000000000370ef0
> [    1.220582] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [    1.220582] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [    1.220582] Call Trace:
> [    1.220582]  internal_create_group+0xde/0x390
> [    1.220582]  internal_create_groups.part.4+0x3e/0xa0
> [    1.220582]  device_add+0x3cf/0x830
> [    1.220582]  ? cdev_get+0x20/0x20
> [    1.220582]  ? cdev_purge+0x60/0x60
> [    1.220582]  cdev_device_add+0x44/0x70
> [    1.220582]  ? cdev_init+0x50/0x60
> [    1.220582]  nvme_alloc_chardev_ns+0x187/0x1eb
> [    1.220582]  nvme_alloc_ns+0x367/0x460
> [    1.220582]  nvme_validate_or_alloc_ns+0xe2/0x139
> [    1.220582]  nvme_scan_ns_list+0x113/0x17a
> [    1.220582]  nvme_scan_work+0xa5/0x106
> [    1.220582]  process_one_work+0x1dd/0x3e0
> [    1.220582]  worker_thread+0x2d/0x3b0
> [    1.220582]  ? cancel_delayed_work+0x90/0x90
> [    1.220582]  kthread+0x117/0x130
> [    1.220582]  ? kthread_park+0x90/0x90
> [    1.220582]  ret_from_fork+0x22/0x30
> [    1.220582] Modules linked in:
> [    1.220582] CR2: 0000000100000041
> [    1.220582] ---[ end trace b1f509a1bbfbc113 ]---
> [    1.220582] RIP: 0010:nvme_ns_id_attrs_are_visible+0x10f/0x152
> [    1.220582] Code: 81 7d d0 80 f9 a1 82 74 0a 48 81 7d d0 a0 f9 a1 82 75 50 48 8b 45 e8 48 89 45 f8 48 8b 45 f8 48 83 e8 60 48 8b 80 60 03 00 00 <48> 8b 40 40 48 3d e0 d1 4d 82 74 07 b8 00 00 00 00 eb 2e 48 8b 45
> [    1.220582] RSP: 0000:ffffc90000047b70 EFLAGS: 00010282
> [    1.220582] RAX: 0000000100000001 RBX: ffffffff824ddb20 RCX: 0000000000000124
> [    1.220582] RDX: ffff8881026eac00 RSI: ffffffff82a1f980 RDI: ffff888102745058
> [    1.220582] RBP: ffffc90000047ba8 R08: ffff888102948718 R09: 0000000000000000
> [    1.220582] R10: 0000000000000000 R11: ffff888100465080 R12: ffff888102745058
> [    1.220582] R13: ffff888102948600 R14: 0000000000000000 R15: ffffffff82a1f548
> [    1.220582] FS:  0000000000000000(0000) GS:ffff88842fc00000(0000) knlGS:0000000000000000
> [    1.220582] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [    1.220582] CR2: 0000000100000041 CR3: 000000000280c001 CR4: 0000000000370ef0
> [    1.220582] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [    1.220582] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> 
> And this happens when CONFIG_NVME_MULTIPATH=y configured.  Please refere
> attached log up there :)
> 
> Thanks!

If this chardev has to have ns_id_attr_group, we need to consider
nvme_ns_id_attrs_are_visible() to take care of dev_to_disk(dev) in case
non-block device.

Thanks!

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Re: nvme: enable char device per namespace

[Javier González]

On 12.01.2021 18:22, Minwoo Im wrote:
>Hello Javier,
>
>I tested this patch based on nvme-5.11:
>
>[    1.219747] BUG: unable to handle page fault for address: 0000000100000041
>[    1.220518] #PF: supervisor read access in kernel mode
>[    1.220582] #PF: error_code(0x0000) - not-present page
>[    1.220582] PGD 0 P4D 0
>[    1.220582] Oops: 0000 [#1] SMP PTI
>[    1.220582] CPU: 0 PID: 7 Comm: kworker/u16:0 Not tainted 5.11.0-rc1+ #46
>[    1.220582] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
>[    1.220582] Workqueue: nvme-wq nvme_scan_work
>[    1.220582] RIP: 0010:nvme_ns_id_attrs_are_visible+0x10f/0x152
>[    1.220582] Code: 81 7d d0 80 f9 a1 82 74 0a 48 81 7d d0 a0 f9 a1 82 75 50 48 8b 45 e8 48 89 45 f8 48 8b 45 f8 48 83 e8 60 48 8b 80 60 03 00 00 <48> 8b 40 40 48 3d e0 d1 4d 82 74 07 b8 00 00 00 00 eb 2e 48 8b 45
>[    1.220582] RSP: 0000:ffffc90000047b70 EFLAGS: 00010282
>[    1.220582] RAX: 0000000100000001 RBX: ffffffff824ddb20 RCX: 0000000000000124
>[    1.220582] RDX: ffff8881026eac00 RSI: ffffffff82a1f980 RDI: ffff888102745058
>[    1.220582] RBP: ffffc90000047ba8 R08: ffff888102948718 R09: 0000000000000000
>[    1.220582] R10: 0000000000000000 R11: ffff888100465080 R12: ffff888102745058
>[    1.220582] R13: ffff888102948600 R14: 0000000000000000 R15: ffffffff82a1f548
>[    1.220582] FS:  0000000000000000(0000) GS:ffff88842fc00000(0000) knlGS:0000000000000000
>[    1.220582] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>[    1.220582] CR2: 0000000100000041 CR3: 000000000280c001 CR4: 0000000000370ef0
>[    1.220582] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>[    1.220582] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>[    1.220582] Call Trace:
>[    1.220582]  internal_create_group+0xde/0x390
>[    1.220582]  internal_create_groups.part.4+0x3e/0xa0
>[    1.220582]  device_add+0x3cf/0x830
>[    1.220582]  ? cdev_get+0x20/0x20
>[    1.220582]  ? cdev_purge+0x60/0x60
>[    1.220582]  cdev_device_add+0x44/0x70
>[    1.220582]  ? cdev_init+0x50/0x60
>[    1.220582]  nvme_alloc_chardev_ns+0x187/0x1eb
>[    1.220582]  nvme_alloc_ns+0x367/0x460
>[    1.220582]  nvme_validate_or_alloc_ns+0xe2/0x139
>[    1.220582]  nvme_scan_ns_list+0x113/0x17a
>[    1.220582]  nvme_scan_work+0xa5/0x106
>[    1.220582]  process_one_work+0x1dd/0x3e0
>[    1.220582]  worker_thread+0x2d/0x3b0
>[    1.220582]  ? cancel_delayed_work+0x90/0x90
>[    1.220582]  kthread+0x117/0x130
>[    1.220582]  ? kthread_park+0x90/0x90
>[    1.220582]  ret_from_fork+0x22/0x30
>[    1.220582] Modules linked in:
>[    1.220582] CR2: 0000000100000041
>[    1.220582] ---[ end trace b1f509a1bbfbc113 ]---
>[    1.220582] RIP: 0010:nvme_ns_id_attrs_are_visible+0x10f/0x152
>[    1.220582] Code: 81 7d d0 80 f9 a1 82 74 0a 48 81 7d d0 a0 f9 a1 82 75 50 48 8b 45 e8 48 89 45 f8 48 8b 45 f8 48 83 e8 60 48 8b 80 60 03 00 00 <48> 8b 40 40 48 3d e0 d1 4d 82 74 07 b8 00 00 00 00 eb 2e 48 8b 45
>[    1.220582] RSP: 0000:ffffc90000047b70 EFLAGS: 00010282
>[    1.220582] RAX: 0000000100000001 RBX: ffffffff824ddb20 RCX: 0000000000000124
>[    1.220582] RDX: ffff8881026eac00 RSI: ffffffff82a1f980 RDI: ffff888102745058
>[    1.220582] RBP: ffffc90000047ba8 R08: ffff888102948718 R09: 0000000000000000
>[    1.220582] R10: 0000000000000000 R11: ffff888100465080 R12: ffff888102745058
>[    1.220582] R13: ffff888102948600 R14: 0000000000000000 R15: ffffffff82a1f548
>[    1.220582] FS:  0000000000000000(0000) GS:ffff88842fc00000(0000) knlGS:0000000000000000
>[    1.220582] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>[    1.220582] CR2: 0000000100000041 CR3: 000000000280c001 CR4: 0000000000370ef0
>[    1.220582] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>[    1.220582] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
>And this happens when CONFIG_NVME_MULTIPATH=y configured.  Please refere
>attached log up there :)
>
>Thanks!

I have not implemented multipath support, but it should definitely not
crash like this. I'll rebase to 5.11 and test.

Christoph: Is it OK to send this without multipath or should I just send
all together?

Javier

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Re: nvme: enable char device per namespace

[Christoph Hellwig]

On Tue, Jan 12, 2021 at 07:30:55PM +0100, Javier González wrote:
> I have not implemented multipath support, but it should definitely not
> crash like this. I'll rebase to 5.11 and test.
>
> Christoph: Is it OK to send this without multipath or should I just send
> all together?

We're not in a rush at the moment, so I'd prefer working multipath
support if you can spare a few cycles.

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Re: nvme: enable char device per namespace

[Javier González]

On 12.01.2021 19:33, Christoph Hellwig wrote:
>On Tue, Jan 12, 2021 at 07:30:55PM +0100, Javier González wrote:
>> I have not implemented multipath support, but it should definitely not
>> crash like this. I'll rebase to 5.11 and test.
>>
>> Christoph: Is it OK to send this without multipath or should I just send
>> all together?
>
>We're not in a rush at the moment, so I'd prefer working multipath
>support if you can spare a few cycles.

Sure. I'll work on that and submit all under the same patchset.

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