--- /dev/null
+The device-mapper uevent code adds the capability to device-mapper to create
+and send kobject uevents (uevents). Previously device-mapper events were only
+available through the ioctl interface. The advantage of the uevents interface
+is the event contains environment attributes providing increased context for
+the event avoiding the need to query the state of the device-mapper device after
+the event is received.
+
+There are two functions currently for device-mapper events. The first function
+listed creates the event and the second function sends the event(s).
+
+void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
+ const char *path, unsigned nr_valid_paths)
+
+void dm_send_uevents(struct list_head *events, struct kobject *kobj)
+
+
+The variables added to the uevent environment are:
+
+Variable Name: DM_TARGET
+Uevent Action(s): KOBJ_CHANGE
+Type: string
+Description:
+Value: Name of device-mapper target that generated the event.
+
+Variable Name: DM_ACTION
+Uevent Action(s): KOBJ_CHANGE
+Type: string
+Description:
+Value: Device-mapper specific action that caused the uevent action.
+ PATH_FAILED - A path has failed.
+ PATH_REINSTATED - A path has been reinstated.
+
+Variable Name: DM_SEQNUM
+Uevent Action(s): KOBJ_CHANGE
+Type: unsigned integer
+Description: A sequence number for this specific device-mapper device.
+Value: Valid unsigned integer range.
+
+Variable Name: DM_PATH
+Uevent Action(s): KOBJ_CHANGE
+Type: string
+Description: Major and minor number of the path device pertaining to this
+event.
+Value: Path name in the form of "Major:Minor"
+
+Variable Name: DM_NR_VALID_PATHS
+Uevent Action(s): KOBJ_CHANGE
+Type: unsigned integer
+Description:
+Value: Valid unsigned integer range.
+
+Variable Name: DM_NAME
+Uevent Action(s): KOBJ_CHANGE
+Type: string
+Description: Name of the device-mapper device.
+Value: Name
+
+Variable Name: DM_UUID
+Uevent Action(s): KOBJ_CHANGE
+Type: string
+Description: UUID of the device-mapper device.
+Value: UUID. (Empty string if there isn't one.)
+
+An example of the uevents generated as captured by udevmonitor is shown
+below.
+
+1.) Path failure.
+UEVENT[1192521009.711215] change@/block/dm-3
+ACTION=change
+DEVPATH=/block/dm-3
+SUBSYSTEM=block
+DM_TARGET=multipath
+DM_ACTION=PATH_FAILED
+DM_SEQNUM=1
+DM_PATH=8:32
+DM_NR_VALID_PATHS=0
+DM_NAME=mpath2
+DM_UUID=mpath-35333333000002328
+MINOR=3
+MAJOR=253
+SEQNUM=1130
+
+2.) Path reinstate.
+UEVENT[1192521132.989927] change@/block/dm-3
+ACTION=change
+DEVPATH=/block/dm-3
+SUBSYSTEM=block
+DM_TARGET=multipath
+DM_ACTION=PATH_REINSTATED
+DM_SEQNUM=2
+DM_PATH=8:32
+DM_NR_VALID_PATHS=1
+DM_NAME=mpath2
+DM_UUID=mpath-35333333000002328
+MINOR=3
+MAJOR=253
+SEQNUM=1131
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/kobject.h>
+#include <linux/dm-ioctl.h>
#include "dm.h"
#include "dm-uevent.h"
#define DM_MSG_PREFIX "uevent"
+static const struct {
+ enum dm_uevent_type type;
+ enum kobject_action action;
+ char *name;
+} _dm_uevent_type_names[] = {
+ {DM_UEVENT_PATH_FAILED, KOBJ_CHANGE, "PATH_FAILED"},
+ {DM_UEVENT_PATH_REINSTATED, KOBJ_CHANGE, "PATH_REINSTATED"},
+};
+
static struct kmem_cache *_dm_event_cache;
struct dm_uevent {
enum kobject_action action;
struct kobj_uevent_env ku_env;
struct list_head elist;
+ char name[DM_NAME_LEN];
+ char uuid[DM_UUID_LEN];
};
static void dm_uevent_free(struct dm_uevent *event)
return event;
}
+static struct dm_uevent *dm_build_path_uevent(struct mapped_device *md,
+ struct dm_target *ti,
+ enum kobject_action action,
+ const char *dm_action,
+ const char *path,
+ unsigned nr_valid_paths)
+{
+ struct dm_uevent *event;
+
+ event = dm_uevent_alloc(md);
+ if (!event) {
+ DMERR("%s: dm_uevent_alloc() failed", __FUNCTION__);
+ goto err_nomem;
+ }
+
+ event->action = action;
+
+ if (add_uevent_var(&event->ku_env, "DM_TARGET=%s", ti->type->name)) {
+ DMERR("%s: add_uevent_var() for DM_TARGET failed",
+ __FUNCTION__);
+ goto err_add;
+ }
+
+ if (add_uevent_var(&event->ku_env, "DM_ACTION=%s", dm_action)) {
+ DMERR("%s: add_uevent_var() for DM_ACTION failed",
+ __FUNCTION__);
+ goto err_add;
+ }
+
+ if (add_uevent_var(&event->ku_env, "DM_SEQNUM=%u",
+ dm_next_uevent_seq(md))) {
+ DMERR("%s: add_uevent_var() for DM_SEQNUM failed",
+ __FUNCTION__);
+ goto err_add;
+ }
+
+ if (add_uevent_var(&event->ku_env, "DM_PATH=%s", path)) {
+ DMERR("%s: add_uevent_var() for DM_PATH failed", __FUNCTION__);
+ goto err_add;
+ }
+
+ if (add_uevent_var(&event->ku_env, "DM_NR_VALID_PATHS=%d",
+ nr_valid_paths)) {
+ DMERR("%s: add_uevent_var() for DM_NR_VALID_PATHS failed",
+ __FUNCTION__);
+ goto err_add;
+ }
+
+ return event;
+
+err_add:
+ dm_uevent_free(event);
+err_nomem:
+ return ERR_PTR(-ENOMEM);
+}
+
+/**
+ * dm_send_uevents - send uevents for given list
+ *
+ * @events: list of events to send
+ * @kobj: kobject generating event
+ *
+ */
+void dm_send_uevents(struct list_head *events, struct kobject *kobj)
+{
+ int r;
+ struct dm_uevent *event, *next;
+
+ list_for_each_entry_safe(event, next, events, elist) {
+ list_del_init(&event->elist);
+
+ /*
+ * Need to call dm_copy_name_and_uuid from here for now.
+ * Context of previous var adds and locking used for
+ * hash_cell not compatable.
+ */
+ if (dm_copy_name_and_uuid(event->md, event->name,
+ event->uuid)) {
+ DMERR("%s: dm_copy_name_and_uuid() failed",
+ __FUNCTION__);
+ goto uevent_free;
+ }
+
+ if (add_uevent_var(&event->ku_env, "DM_NAME=%s", event->name)) {
+ DMERR("%s: add_uevent_var() for DM_NAME failed",
+ __FUNCTION__);
+ goto uevent_free;
+ }
+
+ if (add_uevent_var(&event->ku_env, "DM_UUID=%s", event->uuid)) {
+ DMERR("%s: add_uevent_var() for DM_UUID failed",
+ __FUNCTION__);
+ goto uevent_free;
+ }
+
+ r = kobject_uevent_env(kobj, event->action, event->ku_env.envp);
+ if (r)
+ DMERR("%s: kobject_uevent_env failed", __FUNCTION__);
+uevent_free:
+ dm_uevent_free(event);
+ }
+}
+EXPORT_SYMBOL_GPL(dm_send_uevents);
+
+/**
+ * dm_path_uevent - called to create a new path event and queue it
+ *
+ * @event_type: path event type enum
+ * @ti: pointer to a dm_target
+ * @path: string containing pathname
+ * @nr_valid_paths: number of valid paths remaining
+ *
+ */
+void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
+ const char *path, unsigned nr_valid_paths)
+{
+ struct mapped_device *md = dm_table_get_md(ti->table);
+ struct dm_uevent *event;
+
+ if (event_type >= ARRAY_SIZE(_dm_uevent_type_names)) {
+ DMERR("%s: Invalid event_type %d", __FUNCTION__, event_type);
+ goto out;
+ }
+
+ event = dm_build_path_uevent(md, ti,
+ _dm_uevent_type_names[event_type].action,
+ _dm_uevent_type_names[event_type].name,
+ path, nr_valid_paths);
+ if (IS_ERR(event))
+ goto out;
+
+ dm_uevent_add(md, &event->elist);
+
+out:
+ dm_put(md);
+}
+EXPORT_SYMBOL_GPL(dm_path_uevent);
+
int dm_uevent_init(void)
{
_dm_event_cache = KMEM_CACHE(dm_uevent, 0);
#ifndef DM_UEVENT_H
#define DM_UEVENT_H
+enum dm_uevent_type {
+ DM_UEVENT_PATH_FAILED,
+ DM_UEVENT_PATH_REINSTATED,
+};
+
#ifdef CONFIG_DM_UEVENT
extern int dm_uevent_init(void);
extern void dm_uevent_exit(void);
+extern void dm_send_uevents(struct list_head *events, struct kobject *kobj);
+extern void dm_path_uevent(enum dm_uevent_type event_type,
+ struct dm_target *ti, const char *path,
+ unsigned nr_valid_paths);
#else
static inline void dm_uevent_exit(void)
{
}
+static inline void dm_send_uevents(struct list_head *events,
+ struct kobject *kobj)
+{
+}
+static inline void dm_path_uevent(enum dm_uevent_type event_type,
+ struct dm_target *ti, const char *path,
+ unsigned nr_valid_paths)
+{
+}
#endif /* CONFIG_DM_UEVENT */
*/
atomic_t event_nr;
wait_queue_head_t eventq;
+ atomic_t uevent_seq;
+ struct list_head uevent_list;
+ spinlock_t uevent_lock; /* Protect access to uevent_list */
/*
* freeze/thaw support require holding onto a super block
atomic_set(&md->holders, 1);
atomic_set(&md->open_count, 0);
atomic_set(&md->event_nr, 0);
+ atomic_set(&md->uevent_seq, 0);
+ INIT_LIST_HEAD(&md->uevent_list);
+ spin_lock_init(&md->uevent_lock);
md->queue = blk_alloc_queue(GFP_KERNEL);
if (!md->queue)
*/
static void event_callback(void *context)
{
+ unsigned long flags;
+ LIST_HEAD(uevents);
struct mapped_device *md = (struct mapped_device *) context;
+ spin_lock_irqsave(&md->uevent_lock, flags);
+ list_splice_init(&md->uevent_list, &uevents);
+ spin_unlock_irqrestore(&md->uevent_lock, flags);
+
+ dm_send_uevents(&uevents, &md->disk->kobj);
+
atomic_inc(&md->event_nr);
wake_up(&md->eventq);
}
/*-----------------------------------------------------------------
* Event notification.
*---------------------------------------------------------------*/
+uint32_t dm_next_uevent_seq(struct mapped_device *md)
+{
+ return atomic_add_return(1, &md->uevent_seq);
+}
+
uint32_t dm_get_event_nr(struct mapped_device *md)
{
return atomic_read(&md->event_nr);
(event_nr != atomic_read(&md->event_nr)));
}
+void dm_uevent_add(struct mapped_device *md, struct list_head *elist)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&md->uevent_lock, flags);
+ list_add(elist, &md->uevent_list);
+ spin_unlock_irqrestore(&md->uevent_lock, flags);
+}
+
/*
* The gendisk is only valid as long as you have a reference
* count on 'md'.
*/
uint32_t dm_get_event_nr(struct mapped_device *md);
int dm_wait_event(struct mapped_device *md, int event_nr);
+uint32_t dm_next_uevent_seq(struct mapped_device *md);
+void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
/*
* Info functions.
projects / linux-2.6 / commitdiff