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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

drivers/md/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

drivers/md/dm-sysfs.c

0 → 100644
+99 −0
Original line number Diff line number Diff line 
/*

 * 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));

}

drivers/md/dm.c

+28 −1
Original line number Diff line number Diff line 
/*

 * 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);

drivers/md/dm.h

+8 −0
Original line number Diff line number Diff line
@@ -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

 */