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authorMilan Broz <mbroz@redhat.com>2009-01-06 03:05:12 +0000
committerAlasdair G Kergon <agk@redhat.com>2009-01-06 03:05:12 +0000
commit784aae735d9b0bba3f8b9faef4c8b30df3bf0128 (patch)
tree7e2e956c395b27f63569d7a6adc1098f116cc3a4 /drivers/md/dm-sysfs.c
parentd58168763f74d1edbc296d7038c60efe6493fdd4 (diff)
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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>
Diffstat (limited to 'drivers/md/dm-sysfs.c')
-rw-r--r--drivers/md/dm-sysfs.c99
1 files changed, 99 insertions, 0 deletions
diff --git a/drivers/md/dm-sysfs.c b/drivers/md/dm-sysfs.c
new file mode 100644
index 00000000000..a2a45e6c7c8
--- /dev/null
+++ b/drivers/md/dm-sysfs.c
@@ -0,0 +1,99 @@
+/*
+ * 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));
+}