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    SubjectRe: [PATCH v7 11/14] nvmet-configfs: introduce passthru configfs interface
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    On 8/2/2019 2:45 AM, Logan Gunthorpe wrote:
    > When CONFIG_NVME_TARGET_PASSTHRU as 'passthru' directory will
    > be added to each subsystem. The directory is similar to a namespace
    > and has two attributes: device_path and enable. The user must set the
    > path to the nvme controller's char device and write '1' to enable the
    > subsystem to use passthru.
    >
    > Any given subsystem is prevented from enabling both a regular namespace
    > and the passthru device. If one is enabled, enabling the other will
    > produce an error.
    >
    > Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
    > ---
    > drivers/nvme/target/configfs.c | 99 ++++++++++++++++++++++++++++++++++
    > drivers/nvme/target/nvmet.h | 1 +
    > 2 files changed, 100 insertions(+)
    >
    > diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
    > index 98613a45bd3b..b15d64c19f58 100644
    > --- a/drivers/nvme/target/configfs.c
    > +++ b/drivers/nvme/target/configfs.c
    > @@ -615,6 +615,103 @@ static const struct config_item_type nvmet_namespaces_type = {
    > .ct_owner = THIS_MODULE,
    > };
    >
    > +#ifdef CONFIG_NVME_TARGET_PASSTHRU
    > +
    > +static ssize_t nvmet_passthru_device_path_show(struct config_item *item,
    > + char *page)
    > +{
    > + struct nvmet_subsys *subsys = to_subsys(item->ci_parent);
    > +
    > + return snprintf(page, PAGE_SIZE, "%s\n", subsys->passthru_ctrl_path);
    > +}
    > +
    > +static ssize_t nvmet_passthru_device_path_store(struct config_item *item,
    > + const char *page, size_t count)
    > +{
    > + struct nvmet_subsys *subsys = to_subsys(item->ci_parent);
    > + int ret = -ENOMEM;

    seems like a redundant initialization.

    > + size_t len;
    > +
    > + mutex_lock(&subsys->lock);
    > +
    > + ret = -EBUSY;
    > + if (subsys->passthru_ctrl)
    > + goto out_unlock;
    > +
    > + ret = -EINVAL;
    > + len = strcspn(page, "\n");
    > + if (!len)
    > + goto out_unlock;
    > +
    > + kfree(subsys->passthru_ctrl_path);
    > + ret = -ENOMEM;
    > + subsys->passthru_ctrl_path = kstrndup(page, len, GFP_KERNEL);
    > + if (!subsys->passthru_ctrl_path)
    > + goto out_unlock;
    > +
    > + mutex_unlock(&subsys->lock);
    > +
    > + return count;
    > +out_unlock:
    > + mutex_unlock(&subsys->lock);
    > + return ret;
    > +}
    > +CONFIGFS_ATTR(nvmet_passthru_, device_path);
    > +
    > +static ssize_t nvmet_passthru_enable_show(struct config_item *item,
    > + char *page)
    > +{
    > + struct nvmet_subsys *subsys = to_subsys(item->ci_parent);
    > +
    > + return sprintf(page, "%d\n", subsys->passthru_ctrl ? 1 : 0);
    > +}
    > +
    > +static ssize_t nvmet_passthru_enable_store(struct config_item *item,
    > + const char *page, size_t count)
    > +{
    > + struct nvmet_subsys *subsys = to_subsys(item->ci_parent);
    > + bool enable;
    > + int ret = 0;
    > +
    > + if (strtobool(page, &enable))
    > + return -EINVAL;
    > +
    > + if (enable)
    > + ret = nvmet_passthru_ctrl_enable(subsys);
    > + else
    > + nvmet_passthru_ctrl_disable(subsys);
    > +
    > + return ret ? ret : count;
    > +}
    > +CONFIGFS_ATTR(nvmet_passthru_, enable);
    > +
    > +static struct configfs_attribute *nvmet_passthru_attrs[] = {
    > + &nvmet_passthru_attr_device_path,
    > + &nvmet_passthru_attr_enable,
    > + NULL,
    > +};
    > +
    > +static const struct config_item_type nvmet_passthru_type = {
    > + .ct_attrs = nvmet_passthru_attrs,
    > + .ct_owner = THIS_MODULE,
    > +};
    > +
    > +static void nvmet_add_passthru_group(struct nvmet_subsys *subsys)
    > +{
    > + config_group_init_type_name(&subsys->passthru_group,
    > + "passthru", &nvmet_passthru_type);
    > + configfs_add_default_group(&subsys->passthru_group,
    > + &subsys->group);
    > +}
    > +
    > +#else /* CONFIG_NVME_TARGET_PASSTHRU */
    > +
    > +static void nvmet_add_passthru_group(struct nvmet_subsys *subsys)
    > +{
    > +}
    > +
    > +#endif /* CONFIG_NVME_TARGET_PASSTHRU */
    > +
    > static int nvmet_port_subsys_allow_link(struct config_item *parent,
    > struct config_item *target)
    > {
    > @@ -915,6 +1012,8 @@ static struct config_group *nvmet_subsys_make(struct config_group *group,
    > configfs_add_default_group(&subsys->allowed_hosts_group,
    > &subsys->group);
    >
    > + nvmet_add_passthru_group(subsys);
    > +
    > return &subsys->group;
    > }
    >
    > diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
    > index 6436cb990905..f9c593f1305d 100644
    > --- a/drivers/nvme/target/nvmet.h
    > +++ b/drivers/nvme/target/nvmet.h
    > @@ -231,6 +231,7 @@ struct nvmet_subsys {
    > #ifdef CONFIG_NVME_TARGET_PASSTHRU
    > struct nvme_ctrl *passthru_ctrl;
    > char *passthru_ctrl_path;
    > + struct config_group passthru_group;
    > #endif /* CONFIG_NVME_TARGET_PASSTHRU */
    > };
    >

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