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dm: uevent generate events 

This patch adds support for the dm_path_event dm_send_event functions which
create and send udev events.

Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Mike Anderson 2007-10-19 22:48:01 +01:00 committed by Alasdair G Kergon
parent 51e5b2bd34
commit 7a8c3d3b92
5 changed files with 295 additions and 0 deletions
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97
Documentation/device-mapper/dm-uevent.txt Normal file
View File

@ -0,0 +1,97 @@
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

150
drivers/md/dm-uevent.c
View File

@ -21,12 +21,22 @@
#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 {
@ -34,6 +44,8 @@ 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)
@ -55,6 +67,144 @@ static struct dm_uevent *dm_uevent_alloc(struct mapped_device *md)
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);

18
drivers/md/dm-uevent.h
View File

@ -21,10 +21,19 @@
#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
@ -35,6 +44,15 @@ static inline int dm_uevent_init(void)
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 */

28
drivers/md/dm.c
View File

@ -113,6 +113,9 @@ struct mapped_device {
*/
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
@ -985,6 +988,9 @@ static struct mapped_device *alloc_dev(int minor)
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)
@ -1083,8 +1089,16 @@ static void free_dev(struct mapped_device *md)
*/
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);
}
@ -1502,6 +1516,11 @@ out:
/*-----------------------------------------------------------------
* 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);
@ -1513,6 +1532,15 @@ int dm_wait_event(struct mapped_device *md, int 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'.

2
include/linux/device-mapper.h
View File

@ -183,6 +183,8 @@ int dm_resume(struct mapped_device *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.