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: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>

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: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Milan Broz · Alasdair G Kergon
1 parent d58168763f
Showing 4 changed files with 136 additions and 2 deletions Side-by-side Diff
drivers/md/Makefile
drivers/md/dm-sysfs.c
drivers/md/dm.c
drivers/md/dm.h
@@ -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 @@
  
 	/* forced geometry settings */
 	struct hd_geometry geometry;
+
+	/* sysfs handle */
+	struct kobject kobj;
 };
  
 #define MIN_IOS 256
@@ -1285,6 +1288,8 @@
 	if (!md)
 		return -ENXIO;
  
+	dm_sysfs_init(md);
+
 	*result = md;
 	return 0;
 }
@@ -1360,6 +1365,7 @@
 			dm_table_presuspend_targets(map);
 			dm_table_postsuspend_targets(map);
 		}
+		dm_sysfs_exit(md);
 		dm_table_put(map);
 		__unbind(md);
 		free_dev(md);
@@ -1697,6 +1703,27 @@
 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)
@@ -74,6 +74,14 @@
 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
  */
 int dm_linear_init(void);
...	...	@@ -3,7 +3,7 @@
3	3	#
4	4
5	5	dm-mod-objs := dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
6		- dm-ioctl.o dm-io.o dm-kcopyd.o
	6	+ dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o
7	7	dm-multipath-objs := dm-path-selector.o dm-mpath.o
8	8	dm-snapshot-objs := dm-snap.o dm-exception-store.o
9	9	dm-mirror-objs := dm-raid1.o
	1	+/*
	2	+ * Copyright (C) 2008 Red Hat, Inc. All rights reserved.
	3	+ *
	4	+ * This file is released under the GPL.
	5	+ */
	6	+
	7	+#include <linux/sysfs.h>
	8	+#include <linux/dm-ioctl.h>
	9	+#include "dm.h"
	10	+
	11	+struct dm_sysfs_attr {
	12	+ struct attribute attr;
	13	+ ssize_t (show)(struct mapped_device , char *);
	14	+ ssize_t (store)(struct mapped_device , char *);
	15	+};
	16	+
	17	+#define DM_ATTR_RO(_name) \
	18	+struct dm_sysfs_attr dm_attr_##_name = \
	19	+ __ATTR(_name, S_IRUGO, dm_attr_##_name##_show, NULL)
	20	+
	21	+static ssize_t dm_attr_show(struct kobject kobj, struct attribute attr,
	22	+ char *page)
	23	+{
	24	+ struct dm_sysfs_attr *dm_attr;
	25	+ struct mapped_device *md;
	26	+ ssize_t ret;
	27	+
	28	+ dm_attr = container_of(attr, struct dm_sysfs_attr, attr);
	29	+ if (!dm_attr->show)
	30	+ return -EIO;
	31	+
	32	+ md = dm_get_from_kobject(kobj);
	33	+ if (!md)
	34	+ return -EINVAL;
	35	+
	36	+ ret = dm_attr->show(md, page);
	37	+ dm_put(md);
	38	+
	39	+ return ret;
	40	+}
	41	+
	42	+static ssize_t dm_attr_name_show(struct mapped_device md, char buf)
	43	+{
	44	+ if (dm_copy_name_and_uuid(md, buf, NULL))
	45	+ return -EIO;
	46	+
	47	+ strcat(buf, "\n");
	48	+ return strlen(buf);
	49	+}
	50	+
	51	+static ssize_t dm_attr_uuid_show(struct mapped_device md, char buf)
	52	+{
	53	+ if (dm_copy_name_and_uuid(md, NULL, buf))
	54	+ return -EIO;
	55	+
	56	+ strcat(buf, "\n");
	57	+ return strlen(buf);
	58	+}
	59	+
	60	+static DM_ATTR_RO(name);
	61	+static DM_ATTR_RO(uuid);
	62	+
	63	+static struct attribute *dm_attrs[] = {
	64	+ &dm_attr_name.attr,
	65	+ &dm_attr_uuid.attr,
	66	+ NULL,
	67	+};
	68	+
	69	+static struct sysfs_ops dm_sysfs_ops = {
	70	+ .show = dm_attr_show,
	71	+};
	72	+
	73	+/*
	74	+ * dm kobject is embedded in mapped_device structure
	75	+ * no need to define release function here
	76	+ */
	77	+static struct kobj_type dm_ktype = {
	78	+ .sysfs_ops = &dm_sysfs_ops,
	79	+ .default_attrs = dm_attrs,
	80	+};
	81	+
	82	+/*
	83	+ * Initialize kobj
	84	+ * because nobody using md yet, no need to call explicit dm_get/put
	85	+ */
	86	+int dm_sysfs_init(struct mapped_device *md)
	87	+{
	88	+ return kobject_init_and_add(dm_kobject(md), &dm_ktype,
	89	+ &disk_to_dev(dm_disk(md))->kobj,
	90	+ "%s", "dm");
	91	+}
	92	+
	93	+/*
	94	+ * Remove kobj, called after all references removed
	95	+ */
	96	+void dm_sysfs_exit(struct mapped_device *md)
	97	+{
	98	+ kobject_put(dm_kobject(md));
	99	+}
1	1	/*
2	2	* Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
3		- * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
	3	+ * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
4	4	*
5	5	* This file is released under the GPL.
6	6	*/
...	...	@@ -167,6 +167,9 @@
167	167
168	168	/* forced geometry settings */
169	169	struct hd_geometry geometry;
	170	+
	171	+ /* sysfs handle */
	172	+ struct kobject kobj;
170	173	};
171	174
172	175	#define MIN_IOS 256
...	...	@@ -1285,6 +1288,8 @@
1285	1288	if (!md)
1286	1289	return -ENXIO;
1287	1290
	1291	+ dm_sysfs_init(md);
	1292	+
1288	1293	*result = md;
1289	1294	return 0;
1290	1295	}
...	...	@@ -1360,6 +1365,7 @@
1360	1365	dm_table_presuspend_targets(map);
1361	1366	dm_table_postsuspend_targets(map);
1362	1367	}
	1368	+ dm_sysfs_exit(md);
1363	1369	dm_table_put(map);
1364	1370	__unbind(md);
1365	1371	free_dev(md);
...	...	@@ -1697,6 +1703,27 @@
1697	1703	struct gendisk dm_disk(struct mapped_device md)
1698	1704	{
1699	1705	return md->disk;
	1706	+}
	1707	+
	1708	+struct kobject dm_kobject(struct mapped_device md)
	1709	+{
	1710	+ return &md->kobj;
	1711	+}
	1712	+
	1713	+/*
	1714	+ * struct mapped_device should not be exported outside of dm.c
	1715	+ * so use this check to verify that kobj is part of md structure
	1716	+ */
	1717	+struct mapped_device dm_get_from_kobject(struct kobject kobj)
	1718	+{
	1719	+ struct mapped_device *md;
	1720	+
	1721	+ md = container_of(kobj, struct mapped_device, kobj);
	1722	+ if (&md->kobj != kobj)
	1723	+ return NULL;
	1724	+
	1725	+ dm_get(md);
	1726	+ return md;
1700	1727	}
1701	1728
1702	1729	int dm_suspended(struct mapped_device *md)
...	...	@@ -74,6 +74,14 @@
74	74	void dm_interface_exit(void);
75	75
76	76	/*
	77	+ * sysfs interface
	78	+ */
	79	+int dm_sysfs_init(struct mapped_device *md);
	80	+void dm_sysfs_exit(struct mapped_device *md);
	81	+struct kobject dm_kobject(struct mapped_device md);
	82	+struct mapped_device dm_get_from_kobject(struct kobject kobj);
	83	+
	84	+/*
77	85	* Targets for linear and striped mappings
78	86	*/
79	87	int dm_linear_init(void);