block/rnbd: server: sysfs interface functions

This is the sysfs interface to rnbd mapped devices on server side:

  /sys/class/rnbd-server/ctl/devices/<device_name>/
    |- block_dev
    |  *** link pointing to the corresponding block device sysfs entry
    |
    |- sessions/<session-name>/
    |  *** sessions directory
       |
       |- read_only
       |  *** is devices mapped as read only
       |
       |- mapping_path
          *** relative device path provided by the client during mapping

Link: https://lore.kernel.org/r/20200511135131.27580-23-danil.kipnis@cloud.ionos.com
Signed-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/block/rnbd/rnbd-srv-sysfs.c b/drivers/block/rnbd/rnbd-srv-sysfs.c
new file mode 100644 (file)
index 0000000..106775c
--- /dev/null
+++ b/drivers/block/rnbd/rnbd-srv-sysfs.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * RDMA Network Block Driver
+ *
+ * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
+ * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
+ * Copyright (c) 2019 - 2020 1&1 IONOS SE. All rights reserved.
+ */
+#undef pr_fmt
+#define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt
+
+#include <uapi/linux/limits.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/stat.h>
+#include <linux/genhd.h>
+#include <linux/list.h>
+#include <linux/moduleparam.h>
+#include <linux/device.h>
+
+#include "rnbd-srv.h"
+
+static struct device *rnbd_dev;
+static struct class *rnbd_dev_class;
+static struct kobject *rnbd_devs_kobj;
+
+static void rnbd_srv_dev_release(struct kobject *kobj)
+{
+       struct rnbd_srv_dev *dev;
+
+       dev = container_of(kobj, struct rnbd_srv_dev, dev_kobj);
+
+       kfree(dev);
+}
+
+static struct kobj_type dev_ktype = {
+       .sysfs_ops = &kobj_sysfs_ops,
+       .release = rnbd_srv_dev_release
+};
+
+int rnbd_srv_create_dev_sysfs(struct rnbd_srv_dev *dev,
+                              struct block_device *bdev,
+                              const char *dev_name)
+{
+       struct kobject *bdev_kobj;
+       int ret;
+
+       ret = kobject_init_and_add(&dev->dev_kobj, &dev_ktype,
+                                  rnbd_devs_kobj, dev_name);
+       if (ret)
+               return ret;
+
+       dev->dev_sessions_kobj = kobject_create_and_add("sessions",
+                                                       &dev->dev_kobj);
+       if (!dev->dev_sessions_kobj)
+               goto put_dev_kobj;
+
+       bdev_kobj = &disk_to_dev(bdev->bd_disk)->kobj;
+       ret = sysfs_create_link(&dev->dev_kobj, bdev_kobj, "block_dev");
+       if (ret)
+               goto put_sess_kobj;
+
+       return 0;
+
+put_sess_kobj:
+       kobject_put(dev->dev_sessions_kobj);
+put_dev_kobj:
+       kobject_put(&dev->dev_kobj);
+       return ret;
+}
+
+void rnbd_srv_destroy_dev_sysfs(struct rnbd_srv_dev *dev)
+{
+       sysfs_remove_link(&dev->dev_kobj, "block_dev");
+       kobject_del(dev->dev_sessions_kobj);
+       kobject_put(dev->dev_sessions_kobj);
+       kobject_del(&dev->dev_kobj);
+       kobject_put(&dev->dev_kobj);
+}
+
+static ssize_t read_only_show(struct kobject *kobj, struct kobj_attribute *attr,
+                             char *page)
+{
+       struct rnbd_srv_sess_dev *sess_dev;
+
+       sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);
+
+       return scnprintf(page, PAGE_SIZE, "%d\n",
+                        !(sess_dev->open_flags & FMODE_WRITE));
+}
+
+static struct kobj_attribute rnbd_srv_dev_session_ro_attr =
+       __ATTR_RO(read_only);
+
+static ssize_t access_mode_show(struct kobject *kobj,
+                               struct kobj_attribute *attr,
+                               char *page)
+{
+       struct rnbd_srv_sess_dev *sess_dev;
+
+       sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);
+
+       return scnprintf(page, PAGE_SIZE, "%s\n",
+                        rnbd_access_mode_str(sess_dev->access_mode));
+}
+
+static struct kobj_attribute rnbd_srv_dev_session_access_mode_attr =
+       __ATTR_RO(access_mode);
+
+static ssize_t mapping_path_show(struct kobject *kobj,
+                                struct kobj_attribute *attr, char *page)
+{
+       struct rnbd_srv_sess_dev *sess_dev;
+
+       sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);
+
+       return scnprintf(page, PAGE_SIZE, "%s\n", sess_dev->pathname);
+}
+
+static struct kobj_attribute rnbd_srv_dev_session_mapping_path_attr =
+       __ATTR_RO(mapping_path);
+
+static struct attribute *rnbd_srv_default_dev_sessions_attrs[] = {
+       &rnbd_srv_dev_session_access_mode_attr.attr,
+       &rnbd_srv_dev_session_ro_attr.attr,
+       &rnbd_srv_dev_session_mapping_path_attr.attr,
+       NULL,
+};
+
+static struct attribute_group rnbd_srv_default_dev_session_attr_group = {
+       .attrs = rnbd_srv_default_dev_sessions_attrs,
+};
+
+void rnbd_srv_destroy_dev_session_sysfs(struct rnbd_srv_sess_dev *sess_dev)
+{
+       sysfs_remove_group(&sess_dev->kobj,
+                          &rnbd_srv_default_dev_session_attr_group);
+
+       kobject_del(&sess_dev->kobj);
+       kobject_put(&sess_dev->kobj);
+}
+
+static void rnbd_srv_sess_dev_release(struct kobject *kobj)
+{
+       struct rnbd_srv_sess_dev *sess_dev;
+
+       sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);
+       rnbd_destroy_sess_dev(sess_dev);
+}
+
+static struct kobj_type rnbd_srv_sess_dev_ktype = {
+       .sysfs_ops      = &kobj_sysfs_ops,
+       .release        = rnbd_srv_sess_dev_release,
+};
+
+int rnbd_srv_create_dev_session_sysfs(struct rnbd_srv_sess_dev *sess_dev)
+{
+       int ret;
+
+       ret = kobject_init_and_add(&sess_dev->kobj, &rnbd_srv_sess_dev_ktype,
+                                  sess_dev->dev->dev_sessions_kobj, "%s",
+                                  sess_dev->sess->sessname);
+       if (ret)
+               return ret;
+
+       ret = sysfs_create_group(&sess_dev->kobj,
+                                &rnbd_srv_default_dev_session_attr_group);
+       if (ret)
+               goto err;
+
+       return 0;
+
+err:
+       kobject_put(&sess_dev->kobj);
+
+       return ret;
+}
+
+int rnbd_srv_create_sysfs_files(void)
+{
+       int err;
+
+       rnbd_dev_class = class_create(THIS_MODULE, "rnbd-server");
+       if (IS_ERR(rnbd_dev_class))
+               return PTR_ERR(rnbd_dev_class);
+
+       rnbd_dev = device_create(rnbd_dev_class, NULL,
+                                 MKDEV(0, 0), NULL, "ctl");
+       if (IS_ERR(rnbd_dev)) {
+               err = PTR_ERR(rnbd_dev);
+               goto cls_destroy;
+       }
+       rnbd_devs_kobj = kobject_create_and_add("devices", &rnbd_dev->kobj);
+       if (!rnbd_devs_kobj) {
+               err = -ENOMEM;
+               goto dev_destroy;
+       }
+
+       return 0;
+
+dev_destroy:
+       device_destroy(rnbd_dev_class, MKDEV(0, 0));
+cls_destroy:
+       class_destroy(rnbd_dev_class);
+
+       return err;
+}
+
+void rnbd_srv_destroy_sysfs_files(void)
+{
+       kobject_del(rnbd_devs_kobj);
+       kobject_put(rnbd_devs_kobj);
+       device_destroy(rnbd_dev_class, MKDEV(0, 0));
+       class_destroy(rnbd_dev_class);
+}