Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * Disk events - monitor disk events like media change and eject request.
4 : */
5 : #include <linux/export.h>
6 : #include <linux/moduleparam.h>
7 : #include <linux/blkdev.h>
8 : #include "blk.h"
9 :
10 : struct disk_events {
11 : struct list_head node; /* all disk_event's */
12 : struct gendisk *disk; /* the associated disk */
13 : spinlock_t lock;
14 :
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 */
19 :
20 : long poll_msecs; /* interval, -1 for default */
21 : struct delayed_work dwork;
22 : };
23 :
24 : static const char *disk_events_strs[] = {
25 : [ilog2(DISK_EVENT_MEDIA_CHANGE)] = "media_change",
26 : [ilog2(DISK_EVENT_EJECT_REQUEST)] = "eject_request",
27 : };
28 :
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",
32 : };
33 :
34 : /* list of all disk_events */
35 : static DEFINE_MUTEX(disk_events_mutex);
36 : static LIST_HEAD(disk_events);
37 :
38 : /* disable in-kernel polling by default */
39 : static unsigned long disk_events_dfl_poll_msecs;
40 :
41 0 : static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
42 : {
43 0 : struct disk_events *ev = disk->ev;
44 0 : long intv_msecs = 0;
45 :
46 : /*
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.
49 : */
50 0 : if (ev->poll_msecs >= 0)
51 : intv_msecs = ev->poll_msecs;
52 0 : else if (disk->event_flags & DISK_EVENT_FLAG_POLL)
53 0 : intv_msecs = disk_events_dfl_poll_msecs;
54 :
55 0 : return msecs_to_jiffies(intv_msecs);
56 : }
57 :
58 : /**
59 : * disk_block_events - block and flush disk event checking
60 : * @disk: disk to block events for
61 : *
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.
66 : *
67 : * Note that this intentionally does not block event checking from
68 : * disk_clear_events().
69 : *
70 : * CONTEXT:
71 : * Might sleep.
72 : */
73 0 : void disk_block_events(struct gendisk *disk)
74 : {
75 0 : struct disk_events *ev = disk->ev;
76 : unsigned long flags;
77 : bool cancel;
78 :
79 0 : if (!ev)
80 : return;
81 :
82 : /*
83 : * Outer mutex ensures that the first blocker completes canceling
84 : * the event work before further blockers are allowed to finish.
85 : */
86 0 : mutex_lock(&ev->block_mutex);
87 :
88 0 : spin_lock_irqsave(&ev->lock, flags);
89 0 : cancel = !ev->block++;
90 0 : spin_unlock_irqrestore(&ev->lock, flags);
91 :
92 0 : if (cancel)
93 0 : cancel_delayed_work_sync(&disk->ev->dwork);
94 :
95 0 : mutex_unlock(&ev->block_mutex);
96 : }
97 :
98 0 : static void __disk_unblock_events(struct gendisk *disk, bool check_now)
99 : {
100 0 : struct disk_events *ev = disk->ev;
101 : unsigned long intv;
102 : unsigned long flags;
103 :
104 0 : spin_lock_irqsave(&ev->lock, flags);
105 :
106 0 : if (WARN_ON_ONCE(ev->block <= 0))
107 : goto out_unlock;
108 :
109 0 : if (--ev->block)
110 : goto out_unlock;
111 :
112 0 : intv = disk_events_poll_jiffies(disk);
113 0 : if (check_now)
114 0 : queue_delayed_work(system_freezable_power_efficient_wq,
115 : &ev->dwork, 0);
116 0 : else if (intv)
117 0 : queue_delayed_work(system_freezable_power_efficient_wq,
118 : &ev->dwork, intv);
119 : out_unlock:
120 0 : spin_unlock_irqrestore(&ev->lock, flags);
121 0 : }
122 :
123 : /**
124 : * disk_unblock_events - unblock disk event checking
125 : * @disk: disk to unblock events for
126 : *
127 : * Undo disk_block_events(). When the block count reaches zero, it
128 : * starts events polling if configured.
129 : *
130 : * CONTEXT:
131 : * Don't care. Safe to call from irq context.
132 : */
133 0 : void disk_unblock_events(struct gendisk *disk)
134 : {
135 0 : if (disk->ev)
136 0 : __disk_unblock_events(disk, false);
137 0 : }
138 :
139 : /**
140 : * disk_flush_events - schedule immediate event checking and flushing
141 : * @disk: disk to check and flush events for
142 : * @mask: events to flush
143 : *
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.
147 : *
148 : * CONTEXT:
149 : * If @mask is non-zero must be called with disk->open_mutex held.
150 : */
151 0 : void disk_flush_events(struct gendisk *disk, unsigned int mask)
152 : {
153 0 : struct disk_events *ev = disk->ev;
154 :
155 0 : if (!ev)
156 : return;
157 :
158 0 : spin_lock_irq(&ev->lock);
159 0 : ev->clearing |= mask;
160 0 : if (!ev->block)
161 0 : mod_delayed_work(system_freezable_power_efficient_wq,
162 : &ev->dwork, 0);
163 0 : spin_unlock_irq(&ev->lock);
164 : }
165 :
166 : /*
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.
170 : */
171 0 : static void disk_event_uevent(struct gendisk *disk, unsigned int events)
172 : {
173 0 : char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
174 0 : int nr_events = 0, i;
175 :
176 0 : for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
177 0 : if (events & disk->events & (1 << i))
178 0 : envp[nr_events++] = disk_uevents[i];
179 :
180 0 : if (nr_events)
181 0 : kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
182 0 : }
183 :
184 0 : static void disk_check_events(struct disk_events *ev,
185 : unsigned int *clearing_ptr)
186 : {
187 0 : struct gendisk *disk = ev->disk;
188 0 : unsigned int clearing = *clearing_ptr;
189 : unsigned int events;
190 : unsigned long intv;
191 :
192 : /* check events */
193 0 : events = disk->fops->check_events(disk, clearing);
194 :
195 : /* accumulate pending events and schedule next poll if necessary */
196 0 : spin_lock_irq(&ev->lock);
197 :
198 0 : events &= ~ev->pending;
199 0 : ev->pending |= events;
200 0 : *clearing_ptr &= ~clearing;
201 :
202 0 : intv = disk_events_poll_jiffies(disk);
203 0 : if (!ev->block && intv)
204 0 : queue_delayed_work(system_freezable_power_efficient_wq,
205 : &ev->dwork, intv);
206 :
207 0 : spin_unlock_irq(&ev->lock);
208 :
209 0 : if (events & DISK_EVENT_MEDIA_CHANGE)
210 0 : inc_diskseq(disk);
211 :
212 0 : if (disk->event_flags & DISK_EVENT_FLAG_UEVENT)
213 0 : disk_event_uevent(disk, events);
214 0 : }
215 :
216 : /**
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
220 : *
221 : * Disk events are synchronously checked and pending events in @mask
222 : * are cleared and returned. This ignores the block count.
223 : *
224 : * CONTEXT:
225 : * Might sleep.
226 : */
227 0 : static unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
228 : {
229 0 : struct disk_events *ev = disk->ev;
230 : unsigned int pending;
231 0 : unsigned int clearing = mask;
232 :
233 0 : if (!ev)
234 : return 0;
235 :
236 0 : disk_block_events(disk);
237 :
238 : /*
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).
242 : */
243 0 : spin_lock_irq(&ev->lock);
244 0 : clearing |= ev->clearing;
245 0 : ev->clearing = 0;
246 0 : spin_unlock_irq(&ev->lock);
247 :
248 0 : disk_check_events(ev, &clearing);
249 : /*
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.
252 : */
253 0 : __disk_unblock_events(disk, ev->clearing ? true : false);
254 :
255 : /* then, fetch and clear pending events */
256 0 : spin_lock_irq(&ev->lock);
257 0 : pending = ev->pending & mask;
258 0 : ev->pending &= ~mask;
259 0 : spin_unlock_irq(&ev->lock);
260 0 : WARN_ON_ONCE(clearing & mask);
261 :
262 : return pending;
263 : }
264 :
265 : /**
266 : * disk_check_media_change - check if a removable media has been changed
267 : * @disk: gendisk to check
268 : *
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
271 : * that case.
272 : *
273 : * Returns %true if the media has changed, or %false if not.
274 : */
275 0 : bool disk_check_media_change(struct gendisk *disk)
276 : {
277 : unsigned int events;
278 :
279 0 : events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
280 : DISK_EVENT_EJECT_REQUEST);
281 0 : if (!(events & DISK_EVENT_MEDIA_CHANGE))
282 : return false;
283 :
284 0 : if (__invalidate_device(disk->part0, true))
285 0 : pr_warn("VFS: busy inodes on changed media %s\n",
286 : disk->disk_name);
287 0 : set_bit(GD_NEED_PART_SCAN, &disk->state);
288 0 : return true;
289 : }
290 : EXPORT_SYMBOL(disk_check_media_change);
291 :
292 : /**
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
296 : *
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.
300 : *
301 : * Returns %true if DISK_EVENT_MEDIA_CHANGE was raised, or %false if not.
302 : */
303 0 : bool disk_force_media_change(struct gendisk *disk, unsigned int events)
304 : {
305 0 : disk_event_uevent(disk, events);
306 :
307 0 : if (!(events & DISK_EVENT_MEDIA_CHANGE))
308 : return false;
309 :
310 0 : inc_diskseq(disk);
311 0 : if (__invalidate_device(disk->part0, true))
312 0 : pr_warn("VFS: busy inodes on changed media %s\n",
313 : disk->disk_name);
314 0 : set_bit(GD_NEED_PART_SCAN, &disk->state);
315 0 : return true;
316 : }
317 : EXPORT_SYMBOL_GPL(disk_force_media_change);
318 :
319 : /*
320 : * Separate this part out so that a different pointer for clearing_ptr can be
321 : * passed in for disk_clear_events.
322 : */
323 0 : static void disk_events_workfn(struct work_struct *work)
324 : {
325 0 : struct delayed_work *dwork = to_delayed_work(work);
326 0 : struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
327 :
328 0 : disk_check_events(ev, &ev->clearing);
329 0 : }
330 :
331 : /*
332 : * A disk events enabled device has the following sysfs nodes under
333 : * its /sys/block/X/ directory.
334 : *
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
339 : */
340 0 : static ssize_t __disk_events_show(unsigned int events, char *buf)
341 : {
342 0 : const char *delim = "";
343 0 : ssize_t pos = 0;
344 : int i;
345 :
346 0 : for (i = 0; i < ARRAY_SIZE(disk_events_strs); i++)
347 0 : if (events & (1 << i)) {
348 0 : pos += sprintf(buf + pos, "%s%s",
349 : delim, disk_events_strs[i]);
350 0 : delim = " ";
351 : }
352 0 : if (pos)
353 0 : pos += sprintf(buf + pos, "\n");
354 0 : return pos;
355 : }
356 :
357 0 : static ssize_t disk_events_show(struct device *dev,
358 : struct device_attribute *attr, char *buf)
359 : {
360 0 : struct gendisk *disk = dev_to_disk(dev);
361 :
362 0 : if (!(disk->event_flags & DISK_EVENT_FLAG_UEVENT))
363 : return 0;
364 0 : return __disk_events_show(disk->events, buf);
365 : }
366 :
367 0 : static ssize_t disk_events_async_show(struct device *dev,
368 : struct device_attribute *attr, char *buf)
369 : {
370 0 : return 0;
371 : }
372 :
373 0 : static ssize_t disk_events_poll_msecs_show(struct device *dev,
374 : struct device_attribute *attr,
375 : char *buf)
376 : {
377 0 : struct gendisk *disk = dev_to_disk(dev);
378 :
379 0 : if (!disk->ev)
380 0 : return sprintf(buf, "-1\n");
381 0 : return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
382 : }
383 :
384 0 : static ssize_t disk_events_poll_msecs_store(struct device *dev,
385 : struct device_attribute *attr,
386 : const char *buf, size_t count)
387 : {
388 0 : struct gendisk *disk = dev_to_disk(dev);
389 : long intv;
390 :
391 0 : if (!count || !sscanf(buf, "%ld", &intv))
392 : return -EINVAL;
393 :
394 0 : if (intv < 0 && intv != -1)
395 : return -EINVAL;
396 :
397 0 : if (!disk->ev)
398 : return -ENODEV;
399 :
400 0 : disk_block_events(disk);
401 0 : disk->ev->poll_msecs = intv;
402 0 : __disk_unblock_events(disk, true);
403 0 : return count;
404 : }
405 :
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);
410 :
411 : /*
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.
416 : */
417 0 : static int disk_events_set_dfl_poll_msecs(const char *val,
418 : const struct kernel_param *kp)
419 : {
420 : struct disk_events *ev;
421 : int ret;
422 :
423 0 : ret = param_set_ulong(val, kp);
424 0 : if (ret < 0)
425 : return ret;
426 :
427 0 : mutex_lock(&disk_events_mutex);
428 0 : list_for_each_entry(ev, &disk_events, node)
429 0 : disk_flush_events(ev->disk, 0);
430 0 : mutex_unlock(&disk_events_mutex);
431 0 : return 0;
432 : }
433 :
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,
437 : };
438 :
439 : #undef MODULE_PARAM_PREFIX
440 : #define MODULE_PARAM_PREFIX "block."
441 :
442 : module_param_cb(events_dfl_poll_msecs, &disk_events_dfl_poll_msecs_param_ops,
443 : &disk_events_dfl_poll_msecs, 0644);
444 :
445 : /*
446 : * disk_{alloc|add|del|release}_events - initialize and destroy disk_events.
447 : */
448 0 : int disk_alloc_events(struct gendisk *disk)
449 : {
450 : struct disk_events *ev;
451 :
452 0 : if (!disk->fops->check_events || !disk->events)
453 : return 0;
454 :
455 0 : ev = kzalloc(sizeof(*ev), GFP_KERNEL);
456 0 : if (!ev) {
457 0 : pr_warn("%s: failed to initialize events\n", disk->disk_name);
458 0 : return -ENOMEM;
459 : }
460 :
461 0 : INIT_LIST_HEAD(&ev->node);
462 0 : ev->disk = disk;
463 0 : spin_lock_init(&ev->lock);
464 0 : mutex_init(&ev->block_mutex);
465 0 : ev->block = 1;
466 0 : ev->poll_msecs = -1;
467 0 : INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
468 :
469 0 : disk->ev = ev;
470 0 : return 0;
471 : }
472 :
473 0 : void disk_add_events(struct gendisk *disk)
474 : {
475 0 : if (!disk->ev)
476 : return;
477 :
478 0 : mutex_lock(&disk_events_mutex);
479 0 : list_add_tail(&disk->ev->node, &disk_events);
480 0 : mutex_unlock(&disk_events_mutex);
481 :
482 : /*
483 : * Block count is initialized to 1 and the following initial
484 : * unblock kicks it into action.
485 : */
486 0 : __disk_unblock_events(disk, true);
487 : }
488 :
489 0 : void disk_del_events(struct gendisk *disk)
490 : {
491 0 : if (disk->ev) {
492 0 : disk_block_events(disk);
493 :
494 0 : mutex_lock(&disk_events_mutex);
495 0 : list_del_init(&disk->ev->node);
496 0 : mutex_unlock(&disk_events_mutex);
497 : }
498 0 : }
499 :
500 0 : void disk_release_events(struct gendisk *disk)
501 : {
502 : /* the block count should be 1 from disk_del_events() */
503 0 : WARN_ON_ONCE(disk->ev && disk->ev->block != 1);
504 0 : kfree(disk->ev);
505 0 : }
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