dm-sysfs.c

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/*
 * Copyright (C) 2008 Red Hat, Inc. All rights reserved.
 *
 * This file is released under the GPL.
 */

#include <linux/sysfs.h>
#include <linux/dm-ioctl.h>
#include "dm.h"

struct dm_sysfs_attr {
    struct attribute attr;
    ssize_t (*show)(struct mapped_device *, char *);
    ssize_t (*store)(struct mapped_device *, char *);
};

#define DM_ATTR_RO(_name) \
struct dm_sysfs_attr dm_attr_##_name = \
    __ATTR(_name, S_IRUGO, dm_attr_##_name##_show, NULL)

static ssize_t dm_attr_show(struct kobject *kobj, struct attribute *attr,
                char *page)
{
    struct dm_sysfs_attr *dm_attr;
    struct mapped_device *md;
    ssize_t ret;

    dm_attr = container_of(attr, struct dm_sysfs_attr, attr);
    if (!dm_attr->show)
        return -EIO;

    md = dm_get_from_kobject(kobj);
    if (!md)
        return -EINVAL;

    ret = dm_attr->show(md, page);
    dm_put(md);

    return ret;
}

static ssize_t dm_attr_name_show(struct mapped_device *md, char *buf)
{
    if (dm_copy_name_and_uuid(md, buf, NULL))
        return -EIO;

    strcat(buf, "\n");
    return strlen(buf);
}

static ssize_t dm_attr_uuid_show(struct mapped_device *md, char *buf)
{
    if (dm_copy_name_and_uuid(md, NULL, buf))
        return -EIO;

    strcat(buf, "\n");
    return strlen(buf);
}

static ssize_t dm_attr_suspended_show(struct mapped_device *md, char *buf)
{
    sprintf(buf, "%d\n", dm_suspended_md(md));

    return strlen(buf);
}

static DM_ATTR_RO(name);
static DM_ATTR_RO(uuid);
static DM_ATTR_RO(suspended);

static struct attribute *dm_attrs[] = {
    &dm_attr_name.attr,
    &dm_attr_uuid.attr,
    &dm_attr_suspended.attr,
    NULL,
};

static const struct sysfs_ops dm_sysfs_ops = {
    .show   = dm_attr_show,
};

/*
 * dm kobject is embedded in mapped_device structure
 * no need to define release function here
 */
static struct kobj_type dm_ktype = {
    .sysfs_ops  = &dm_sysfs_ops,
    .default_attrs  = dm_attrs,
};

/*
 * Initialize kobj
 * because nobody using md yet, no need to call explicit dm_get/put
 */
int dm_sysfs_init(struct mapped_device *md)
{
    return kobject_init_and_add(dm_kobject(md), &dm_ktype,
                    &disk_to_dev(dm_disk(md))->kobj,
                    "%s", "dm");
}

/*
 * Remove kobj, called after all references removed
 */
void dm_sysfs_exit(struct mapped_device *md)
{
    kobject_put(dm_kobject(md));
}