Commit 784aae73 authored by Milan Broz's avatar Milan Broz Committed by Alasdair G Kergon
Browse files

dm: add name and uuid to sysfs



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: default avatarMilan Broz <mbroz@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent d5816876
......@@ -3,7 +3,7 @@
#
dm-mod-objs := dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
dm-ioctl.o dm-io.o dm-kcopyd.o
dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o
dm-multipath-objs := dm-path-selector.o dm-mpath.o
dm-snapshot-objs := dm-snap.o dm-exception-store.o
dm-mirror-objs := dm-raid1.o
......
/*
* 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 DM_ATTR_RO(name);
static DM_ATTR_RO(uuid);
static struct attribute *dm_attrs[] = {
&dm_attr_name.attr,
&dm_attr_uuid.attr,
NULL,
};
static 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));
}
/*
* Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
* Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
*
* This file is released under the GPL.
*/
......@@ -167,6 +167,9 @@ struct mapped_device {
/* forced geometry settings */
struct hd_geometry geometry;
/* sysfs handle */
struct kobject kobj;
};
#define MIN_IOS 256
......@@ -1285,6 +1288,8 @@ int dm_create(int minor, struct mapped_device **result)
if (!md)
return -ENXIO;
dm_sysfs_init(md);
*result = md;
return 0;
}
......@@ -1360,6 +1365,7 @@ void dm_put(struct mapped_device *md)
dm_table_presuspend_targets(map);
dm_table_postsuspend_targets(map);
}
dm_sysfs_exit(md);
dm_table_put(map);
__unbind(md);
free_dev(md);
......@@ -1699,6 +1705,27 @@ struct gendisk *dm_disk(struct mapped_device *md)
return md->disk;
}
struct kobject *dm_kobject(struct mapped_device *md)
{
return &md->kobj;
}
/*
* struct mapped_device should not be exported outside of dm.c
* so use this check to verify that kobj is part of md structure
*/
struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
{
struct mapped_device *md;
md = container_of(kobj, struct mapped_device, kobj);
if (&md->kobj != kobj)
return NULL;
dm_get(md);
return md;
}
int dm_suspended(struct mapped_device *md)
{
return test_bit(DMF_SUSPENDED, &md->flags);
......
......@@ -73,6 +73,14 @@ int dm_split_args(int *argc, char ***argvp, char *input);
int dm_interface_init(void);
void dm_interface_exit(void);
/*
* sysfs interface
*/
int dm_sysfs_init(struct mapped_device *md);
void dm_sysfs_exit(struct mapped_device *md);
struct kobject *dm_kobject(struct mapped_device *md);
struct mapped_device *dm_get_from_kobject(struct kobject *kobj);
/*
* Targets for linear and striped mappings
*/
......
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