784aae735d
Implement simple read-only sysfs entry for device-mapper block device. This patch adds a simple sysfs directory named "dm" under block device properties and implements - name attribute (string containing mapped device name) - uuid attribute (string containing UUID, or empty string if not set) The kobject is embedded in mapped_device struct, so no additional memory allocation is needed for initializing sysfs entry. During the processing of sysfs attribute we need to lock mapped device which is done by a new function dm_get_from_kobj, which returns the md associated with kobject and increases the usage count. Each 'show attribute' function is responsible for its own locking. Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
100 lines
2.0 KiB
C
100 lines
2.0 KiB
C
/*
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* Copyright (C) 2008 Red Hat, Inc. All rights reserved.
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*
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* This file is released under the GPL.
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*/
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#include <linux/sysfs.h>
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#include <linux/dm-ioctl.h>
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#include "dm.h"
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struct dm_sysfs_attr {
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struct attribute attr;
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ssize_t (*show)(struct mapped_device *, char *);
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ssize_t (*store)(struct mapped_device *, char *);
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};
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#define DM_ATTR_RO(_name) \
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struct dm_sysfs_attr dm_attr_##_name = \
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__ATTR(_name, S_IRUGO, dm_attr_##_name##_show, NULL)
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static ssize_t dm_attr_show(struct kobject *kobj, struct attribute *attr,
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char *page)
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{
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struct dm_sysfs_attr *dm_attr;
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struct mapped_device *md;
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ssize_t ret;
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dm_attr = container_of(attr, struct dm_sysfs_attr, attr);
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if (!dm_attr->show)
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return -EIO;
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md = dm_get_from_kobject(kobj);
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if (!md)
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return -EINVAL;
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ret = dm_attr->show(md, page);
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dm_put(md);
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return ret;
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}
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static ssize_t dm_attr_name_show(struct mapped_device *md, char *buf)
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{
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if (dm_copy_name_and_uuid(md, buf, NULL))
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return -EIO;
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strcat(buf, "\n");
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return strlen(buf);
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}
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static ssize_t dm_attr_uuid_show(struct mapped_device *md, char *buf)
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{
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if (dm_copy_name_and_uuid(md, NULL, buf))
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return -EIO;
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strcat(buf, "\n");
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return strlen(buf);
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}
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static DM_ATTR_RO(name);
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static DM_ATTR_RO(uuid);
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static struct attribute *dm_attrs[] = {
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&dm_attr_name.attr,
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&dm_attr_uuid.attr,
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NULL,
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};
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static struct sysfs_ops dm_sysfs_ops = {
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.show = dm_attr_show,
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};
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/*
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* dm kobject is embedded in mapped_device structure
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* no need to define release function here
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*/
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static struct kobj_type dm_ktype = {
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.sysfs_ops = &dm_sysfs_ops,
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.default_attrs = dm_attrs,
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};
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/*
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* Initialize kobj
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* because nobody using md yet, no need to call explicit dm_get/put
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*/
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int dm_sysfs_init(struct mapped_device *md)
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{
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return kobject_init_and_add(dm_kobject(md), &dm_ktype,
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&disk_to_dev(dm_disk(md))->kobj,
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"%s", "dm");
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}
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/*
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* Remove kobj, called after all references removed
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*/
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void dm_sysfs_exit(struct mapped_device *md)
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{
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kobject_put(dm_kobject(md));
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}
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