1 // SPDX-License-Identifier: GPL-2.0
3 * Disk events - monitor disk events like media change and eject request.
5 #include <linux/export.h>
6 #include <linux/moduleparam.h>
7 #include <linux/blkdev.h>
11 struct list_head node; /* all disk_event's */
12 struct gendisk *disk; /* the associated disk */
15 struct mutex block_mutex; /* protects blocking */
16 int block; /* event blocking depth */
17 unsigned int pending; /* events already sent out */
18 unsigned int clearing; /* events being cleared */
20 long poll_msecs; /* interval, -1 for default */
21 struct delayed_work dwork;
24 static const char *disk_events_strs[] = {
25 [ilog2(DISK_EVENT_MEDIA_CHANGE)] = "media_change",
26 [ilog2(DISK_EVENT_EJECT_REQUEST)] = "eject_request",
29 static char *disk_uevents[] = {
30 [ilog2(DISK_EVENT_MEDIA_CHANGE)] = "DISK_MEDIA_CHANGE=1",
31 [ilog2(DISK_EVENT_EJECT_REQUEST)] = "DISK_EJECT_REQUEST=1",
34 /* list of all disk_events */
35 static DEFINE_MUTEX(disk_events_mutex);
36 static LIST_HEAD(disk_events);
38 /* disable in-kernel polling by default */
39 static unsigned long disk_events_dfl_poll_msecs;
41 static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
43 struct disk_events *ev = disk->ev;
47 * If device-specific poll interval is set, always use it. If
48 * the default is being used, poll if the POLL flag is set.
50 if (ev->poll_msecs >= 0)
51 intv_msecs = ev->poll_msecs;
52 else if (disk->event_flags & DISK_EVENT_FLAG_POLL)
53 intv_msecs = disk_events_dfl_poll_msecs;
55 return msecs_to_jiffies(intv_msecs);
59 * disk_block_events - block and flush disk event checking
60 * @disk: disk to block events for
62 * On return from this function, it is guaranteed that event checking
63 * isn't in progress and won't happen until unblocked by
64 * disk_unblock_events(). Events blocking is counted and the actual
65 * unblocking happens after the matching number of unblocks are done.
67 * Note that this intentionally does not block event checking from
68 * disk_clear_events().
73 void disk_block_events(struct gendisk *disk)
75 struct disk_events *ev = disk->ev;
83 * Outer mutex ensures that the first blocker completes canceling
84 * the event work before further blockers are allowed to finish.
86 mutex_lock(&ev->block_mutex);
88 spin_lock_irqsave(&ev->lock, flags);
89 cancel = !ev->block++;
90 spin_unlock_irqrestore(&ev->lock, flags);
93 cancel_delayed_work_sync(&disk->ev->dwork);
95 mutex_unlock(&ev->block_mutex);
98 static void __disk_unblock_events(struct gendisk *disk, bool check_now)
100 struct disk_events *ev = disk->ev;
104 spin_lock_irqsave(&ev->lock, flags);
106 if (WARN_ON_ONCE(ev->block <= 0))
112 intv = disk_events_poll_jiffies(disk);
114 queue_delayed_work(system_freezable_power_efficient_wq,
117 queue_delayed_work(system_freezable_power_efficient_wq,
120 spin_unlock_irqrestore(&ev->lock, flags);
124 * disk_unblock_events - unblock disk event checking
125 * @disk: disk to unblock events for
127 * Undo disk_block_events(). When the block count reaches zero, it
128 * starts events polling if configured.
131 * Don't care. Safe to call from irq context.
133 void disk_unblock_events(struct gendisk *disk)
136 __disk_unblock_events(disk, false);
140 * disk_flush_events - schedule immediate event checking and flushing
141 * @disk: disk to check and flush events for
142 * @mask: events to flush
144 * Schedule immediate event checking on @disk if not blocked. Events in
145 * @mask are scheduled to be cleared from the driver. Note that this
146 * doesn't clear the events from @disk->ev.
149 * If @mask is non-zero must be called with disk->open_mutex held.
151 void disk_flush_events(struct gendisk *disk, unsigned int mask)
153 struct disk_events *ev = disk->ev;
158 spin_lock_irq(&ev->lock);
159 ev->clearing |= mask;
161 mod_delayed_work(system_freezable_power_efficient_wq,
163 spin_unlock_irq(&ev->lock);
167 * Tell userland about new events. Only the events listed in @disk->events are
168 * reported, and only if DISK_EVENT_FLAG_UEVENT is set. Otherwise, events are
169 * processed internally but never get reported to userland.
171 static void disk_event_uevent(struct gendisk *disk, unsigned int events)
173 char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
174 int nr_events = 0, i;
176 for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
177 if (events & disk->events & (1 << i))
178 envp[nr_events++] = disk_uevents[i];
181 kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
184 static void disk_check_events(struct disk_events *ev,
185 unsigned int *clearing_ptr)
187 struct gendisk *disk = ev->disk;
188 unsigned int clearing = *clearing_ptr;
193 events = disk->fops->check_events(disk, clearing);
195 /* accumulate pending events and schedule next poll if necessary */
196 spin_lock_irq(&ev->lock);
198 events &= ~ev->pending;
199 ev->pending |= events;
200 *clearing_ptr &= ~clearing;
202 intv = disk_events_poll_jiffies(disk);
203 if (!ev->block && intv)
204 queue_delayed_work(system_freezable_power_efficient_wq,
207 spin_unlock_irq(&ev->lock);
209 if (events & DISK_EVENT_MEDIA_CHANGE)
212 if (disk->event_flags & DISK_EVENT_FLAG_UEVENT)
213 disk_event_uevent(disk, events);
217 * disk_clear_events - synchronously check, clear and return pending events
218 * @disk: disk to fetch and clear events from
219 * @mask: mask of events to be fetched and cleared
221 * Disk events are synchronously checked and pending events in @mask
222 * are cleared and returned. This ignores the block count.
227 static unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
229 struct disk_events *ev = disk->ev;
230 unsigned int pending;
231 unsigned int clearing = mask;
236 disk_block_events(disk);
239 * store the union of mask and ev->clearing on the stack so that the
240 * race with disk_flush_events does not cause ambiguity (ev->clearing
241 * can still be modified even if events are blocked).
243 spin_lock_irq(&ev->lock);
244 clearing |= ev->clearing;
246 spin_unlock_irq(&ev->lock);
248 disk_check_events(ev, &clearing);
250 * if ev->clearing is not 0, the disk_flush_events got called in the
251 * middle of this function, so we want to run the workfn without delay.
253 __disk_unblock_events(disk, ev->clearing ? true : false);
255 /* then, fetch and clear pending events */
256 spin_lock_irq(&ev->lock);
257 pending = ev->pending & mask;
258 ev->pending &= ~mask;
259 spin_unlock_irq(&ev->lock);
260 WARN_ON_ONCE(clearing & mask);
266 * disk_check_media_change - check if a removable media has been changed
267 * @disk: gendisk to check
269 * Check whether a removable media has been changed, and attempt to free all
270 * dentries and inodes and invalidates all block device page cache entries in
273 * Returns %true if the media has changed, or %false if not.
275 bool disk_check_media_change(struct gendisk *disk)
279 events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
280 DISK_EVENT_EJECT_REQUEST);
281 if (!(events & DISK_EVENT_MEDIA_CHANGE))
284 if (__invalidate_device(disk->part0, true))
285 pr_warn("VFS: busy inodes on changed media %s\n",
287 set_bit(GD_NEED_PART_SCAN, &disk->state);
290 EXPORT_SYMBOL(disk_check_media_change);
293 * disk_force_media_change - force a media change event
294 * @disk: the disk which will raise the event
295 * @events: the events to raise
297 * Generate uevents for the disk. If DISK_EVENT_MEDIA_CHANGE is present,
298 * attempt to free all dentries and inodes and invalidates all block
299 * device page cache entries in that case.
301 * Returns %true if DISK_EVENT_MEDIA_CHANGE was raised, or %false if not.
303 bool disk_force_media_change(struct gendisk *disk, unsigned int events)
305 disk_event_uevent(disk, events);
307 if (!(events & DISK_EVENT_MEDIA_CHANGE))
311 if (__invalidate_device(disk->part0, true))
312 pr_warn("VFS: busy inodes on changed media %s\n",
314 set_bit(GD_NEED_PART_SCAN, &disk->state);
317 EXPORT_SYMBOL_GPL(disk_force_media_change);
320 * Separate this part out so that a different pointer for clearing_ptr can be
321 * passed in for disk_clear_events.
323 static void disk_events_workfn(struct work_struct *work)
325 struct delayed_work *dwork = to_delayed_work(work);
326 struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
328 disk_check_events(ev, &ev->clearing);
332 * A disk events enabled device has the following sysfs nodes under
333 * its /sys/block/X/ directory.
335 * events : list of all supported events
336 * events_async : list of events which can be detected w/o polling
337 * (always empty, only for backwards compatibility)
338 * events_poll_msecs : polling interval, 0: disable, -1: system default
340 static ssize_t __disk_events_show(unsigned int events, char *buf)
342 const char *delim = "";
346 for (i = 0; i < ARRAY_SIZE(disk_events_strs); i++)
347 if (events & (1 << i)) {
348 pos += sprintf(buf + pos, "%s%s",
349 delim, disk_events_strs[i]);
353 pos += sprintf(buf + pos, "\n");
357 static ssize_t disk_events_show(struct device *dev,
358 struct device_attribute *attr, char *buf)
360 struct gendisk *disk = dev_to_disk(dev);
362 if (!(disk->event_flags & DISK_EVENT_FLAG_UEVENT))
364 return __disk_events_show(disk->events, buf);
367 static ssize_t disk_events_async_show(struct device *dev,
368 struct device_attribute *attr, char *buf)
373 static ssize_t disk_events_poll_msecs_show(struct device *dev,
374 struct device_attribute *attr,
377 struct gendisk *disk = dev_to_disk(dev);
380 return sprintf(buf, "-1\n");
381 return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
384 static ssize_t disk_events_poll_msecs_store(struct device *dev,
385 struct device_attribute *attr,
386 const char *buf, size_t count)
388 struct gendisk *disk = dev_to_disk(dev);
391 if (!count || !sscanf(buf, "%ld", &intv))
394 if (intv < 0 && intv != -1)
400 disk_block_events(disk);
401 disk->ev->poll_msecs = intv;
402 __disk_unblock_events(disk, true);
406 DEVICE_ATTR(events, 0444, disk_events_show, NULL);
407 DEVICE_ATTR(events_async, 0444, disk_events_async_show, NULL);
408 DEVICE_ATTR(events_poll_msecs, 0644, disk_events_poll_msecs_show,
409 disk_events_poll_msecs_store);
412 * The default polling interval can be specified by the kernel
413 * parameter block.events_dfl_poll_msecs which defaults to 0
414 * (disable). This can also be modified runtime by writing to
415 * /sys/module/block/parameters/events_dfl_poll_msecs.
417 static int disk_events_set_dfl_poll_msecs(const char *val,
418 const struct kernel_param *kp)
420 struct disk_events *ev;
423 ret = param_set_ulong(val, kp);
427 mutex_lock(&disk_events_mutex);
428 list_for_each_entry(ev, &disk_events, node)
429 disk_flush_events(ev->disk, 0);
430 mutex_unlock(&disk_events_mutex);
434 static const struct kernel_param_ops disk_events_dfl_poll_msecs_param_ops = {
435 .set = disk_events_set_dfl_poll_msecs,
436 .get = param_get_ulong,
439 #undef MODULE_PARAM_PREFIX
440 #define MODULE_PARAM_PREFIX "block."
442 module_param_cb(events_dfl_poll_msecs, &disk_events_dfl_poll_msecs_param_ops,
443 &disk_events_dfl_poll_msecs, 0644);
446 * disk_{alloc|add|del|release}_events - initialize and destroy disk_events.
448 int disk_alloc_events(struct gendisk *disk)
450 struct disk_events *ev;
452 if (!disk->fops->check_events || !disk->events)
455 ev = kzalloc(sizeof(*ev), GFP_KERNEL);
457 pr_warn("%s: failed to initialize events\n", disk->disk_name);
461 INIT_LIST_HEAD(&ev->node);
463 spin_lock_init(&ev->lock);
464 mutex_init(&ev->block_mutex);
467 INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
473 void disk_add_events(struct gendisk *disk)
478 mutex_lock(&disk_events_mutex);
479 list_add_tail(&disk->ev->node, &disk_events);
480 mutex_unlock(&disk_events_mutex);
483 * Block count is initialized to 1 and the following initial
484 * unblock kicks it into action.
486 __disk_unblock_events(disk, true);
489 void disk_del_events(struct gendisk *disk)
492 disk_block_events(disk);
494 mutex_lock(&disk_events_mutex);
495 list_del_init(&disk->ev->node);
496 mutex_unlock(&disk_events_mutex);
500 void disk_release_events(struct gendisk *disk)
502 /* the block count should be 1 from disk_del_events() */
503 WARN_ON_ONCE(disk->ev && disk->ev->block != 1);