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TOMOYO Linux Cross Reference
Linux/kernel/trace/blktrace.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
  4  *
  5  */
  6 #include <linux/kernel.h>
  7 #include <linux/blkdev.h>
  8 #include <linux/blktrace_api.h>
  9 #include <linux/percpu.h>
 10 #include <linux/init.h>
 11 #include <linux/mutex.h>
 12 #include <linux/slab.h>
 13 #include <linux/debugfs.h>
 14 #include <linux/export.h>
 15 #include <linux/time.h>
 16 #include <linux/uaccess.h>
 17 #include <linux/list.h>
 18 #include <linux/blk-cgroup.h>
 19 
 20 #include "../../block/blk.h"
 21 
 22 #include <trace/events/block.h>
 23 
 24 #include "trace_output.h"
 25 
 26 #ifdef CONFIG_BLK_DEV_IO_TRACE
 27 
 28 static unsigned int blktrace_seq __read_mostly = 1;
 29 
 30 static struct trace_array *blk_tr;
 31 static bool blk_tracer_enabled __read_mostly;
 32 
 33 static LIST_HEAD(running_trace_list);
 34 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock);
 35 
 36 /* Select an alternative, minimalistic output than the original one */
 37 #define TRACE_BLK_OPT_CLASSIC   0x1
 38 #define TRACE_BLK_OPT_CGROUP    0x2
 39 #define TRACE_BLK_OPT_CGNAME    0x4
 40 
 41 static struct tracer_opt blk_tracer_opts[] = {
 42         /* Default disable the minimalistic output */
 43         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
 44 #ifdef CONFIG_BLK_CGROUP
 45         { TRACER_OPT(blk_cgroup, TRACE_BLK_OPT_CGROUP) },
 46         { TRACER_OPT(blk_cgname, TRACE_BLK_OPT_CGNAME) },
 47 #endif
 48         { }
 49 };
 50 
 51 static struct tracer_flags blk_tracer_flags = {
 52         .val  = 0,
 53         .opts = blk_tracer_opts,
 54 };
 55 
 56 /* Global reference count of probes */
 57 static DEFINE_MUTEX(blk_probe_mutex);
 58 static int blk_probes_ref;
 59 
 60 static void blk_register_tracepoints(void);
 61 static void blk_unregister_tracepoints(void);
 62 
 63 /*
 64  * Send out a notify message.
 65  */
 66 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 67                        const void *data, size_t len, u64 cgid)
 68 {
 69         struct blk_io_trace *t;
 70         struct ring_buffer_event *event = NULL;
 71         struct ring_buffer *buffer = NULL;
 72         int pc = 0;
 73         int cpu = smp_processor_id();
 74         bool blk_tracer = blk_tracer_enabled;
 75         ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
 76 
 77         if (blk_tracer) {
 78                 buffer = blk_tr->trace_buffer.buffer;
 79                 pc = preempt_count();
 80                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 81                                                   sizeof(*t) + len + cgid_len,
 82                                                   0, pc);
 83                 if (!event)
 84                         return;
 85                 t = ring_buffer_event_data(event);
 86                 goto record_it;
 87         }
 88 
 89         if (!bt->rchan)
 90                 return;
 91 
 92         t = relay_reserve(bt->rchan, sizeof(*t) + len + cgid_len);
 93         if (t) {
 94                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 95                 t->time = ktime_to_ns(ktime_get());
 96 record_it:
 97                 t->device = bt->dev;
 98                 t->action = action | (cgid ? __BLK_TN_CGROUP : 0);
 99                 t->pid = pid;
100                 t->cpu = cpu;
101                 t->pdu_len = len + cgid_len;
102                 if (cgid_len)
103                         memcpy((void *)t + sizeof(*t), &cgid, cgid_len);
104                 memcpy((void *) t + sizeof(*t) + cgid_len, data, len);
105 
106                 if (blk_tracer)
107                         trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
108         }
109 }
110 
111 /*
112  * Send out a notify for this process, if we haven't done so since a trace
113  * started
114  */
115 static void trace_note_tsk(struct task_struct *tsk)
116 {
117         unsigned long flags;
118         struct blk_trace *bt;
119 
120         tsk->btrace_seq = blktrace_seq;
121         spin_lock_irqsave(&running_trace_lock, flags);
122         list_for_each_entry(bt, &running_trace_list, running_list) {
123                 trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm,
124                            sizeof(tsk->comm), 0);
125         }
126         spin_unlock_irqrestore(&running_trace_lock, flags);
127 }
128 
129 static void trace_note_time(struct blk_trace *bt)
130 {
131         struct timespec64 now;
132         unsigned long flags;
133         u32 words[2];
134 
135         /* need to check user space to see if this breaks in y2038 or y2106 */
136         ktime_get_real_ts64(&now);
137         words[0] = (u32)now.tv_sec;
138         words[1] = now.tv_nsec;
139 
140         local_irq_save(flags);
141         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words), 0);
142         local_irq_restore(flags);
143 }
144 
145 void __trace_note_message(struct blk_trace *bt, struct blkcg *blkcg,
146         const char *fmt, ...)
147 {
148         int n;
149         va_list args;
150         unsigned long flags;
151         char *buf;
152 
153         if (unlikely(bt->trace_state != Blktrace_running &&
154                      !blk_tracer_enabled))
155                 return;
156 
157         /*
158          * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
159          * message to the trace.
160          */
161         if (!(bt->act_mask & BLK_TC_NOTIFY))
162                 return;
163 
164         local_irq_save(flags);
165         buf = this_cpu_ptr(bt->msg_data);
166         va_start(args, fmt);
167         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
168         va_end(args);
169 
170         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
171                 blkcg = NULL;
172 #ifdef CONFIG_BLK_CGROUP
173         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n,
174                    blkcg ? cgroup_id(blkcg->css.cgroup) : 1);
175 #else
176         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n, 0);
177 #endif
178         local_irq_restore(flags);
179 }
180 EXPORT_SYMBOL_GPL(__trace_note_message);
181 
182 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
183                          pid_t pid)
184 {
185         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
186                 return 1;
187         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
188                 return 1;
189         if (bt->pid && pid != bt->pid)
190                 return 1;
191 
192         return 0;
193 }
194 
195 /*
196  * Data direction bit lookup
197  */
198 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
199                                  BLK_TC_ACT(BLK_TC_WRITE) };
200 
201 #define BLK_TC_RAHEAD           BLK_TC_AHEAD
202 #define BLK_TC_PREFLUSH         BLK_TC_FLUSH
203 
204 /* The ilog2() calls fall out because they're constant */
205 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
206           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
207 
208 /*
209  * The worker for the various blk_add_trace*() types. Fills out a
210  * blk_io_trace structure and places it in a per-cpu subbuffer.
211  */
212 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
213                      int op, int op_flags, u32 what, int error, int pdu_len,
214                      void *pdu_data, u64 cgid)
215 {
216         struct task_struct *tsk = current;
217         struct ring_buffer_event *event = NULL;
218         struct ring_buffer *buffer = NULL;
219         struct blk_io_trace *t;
220         unsigned long flags = 0;
221         unsigned long *sequence;
222         pid_t pid;
223         int cpu, pc = 0;
224         bool blk_tracer = blk_tracer_enabled;
225         ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
226 
227         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
228                 return;
229 
230         what |= ddir_act[op_is_write(op) ? WRITE : READ];
231         what |= MASK_TC_BIT(op_flags, SYNC);
232         what |= MASK_TC_BIT(op_flags, RAHEAD);
233         what |= MASK_TC_BIT(op_flags, META);
234         what |= MASK_TC_BIT(op_flags, PREFLUSH);
235         what |= MASK_TC_BIT(op_flags, FUA);
236         if (op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE)
237                 what |= BLK_TC_ACT(BLK_TC_DISCARD);
238         if (op == REQ_OP_FLUSH)
239                 what |= BLK_TC_ACT(BLK_TC_FLUSH);
240         if (cgid)
241                 what |= __BLK_TA_CGROUP;
242 
243         pid = tsk->pid;
244         if (act_log_check(bt, what, sector, pid))
245                 return;
246         cpu = raw_smp_processor_id();
247 
248         if (blk_tracer) {
249                 tracing_record_cmdline(current);
250 
251                 buffer = blk_tr->trace_buffer.buffer;
252                 pc = preempt_count();
253                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
254                                                   sizeof(*t) + pdu_len + cgid_len,
255                                                   0, pc);
256                 if (!event)
257                         return;
258                 t = ring_buffer_event_data(event);
259                 goto record_it;
260         }
261 
262         if (unlikely(tsk->btrace_seq != blktrace_seq))
263                 trace_note_tsk(tsk);
264 
265         /*
266          * A word about the locking here - we disable interrupts to reserve
267          * some space in the relay per-cpu buffer, to prevent an irq
268          * from coming in and stepping on our toes.
269          */
270         local_irq_save(flags);
271         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len + cgid_len);
272         if (t) {
273                 sequence = per_cpu_ptr(bt->sequence, cpu);
274 
275                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
276                 t->sequence = ++(*sequence);
277                 t->time = ktime_to_ns(ktime_get());
278 record_it:
279                 /*
280                  * These two are not needed in ftrace as they are in the
281                  * generic trace_entry, filled by tracing_generic_entry_update,
282                  * but for the trace_event->bin() synthesizer benefit we do it
283                  * here too.
284                  */
285                 t->cpu = cpu;
286                 t->pid = pid;
287 
288                 t->sector = sector;
289                 t->bytes = bytes;
290                 t->action = what;
291                 t->device = bt->dev;
292                 t->error = error;
293                 t->pdu_len = pdu_len + cgid_len;
294 
295                 if (cgid_len)
296                         memcpy((void *)t + sizeof(*t), &cgid, cgid_len);
297                 if (pdu_len)
298                         memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len);
299 
300                 if (blk_tracer) {
301                         trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
302                         return;
303                 }
304         }
305 
306         local_irq_restore(flags);
307 }
308 
309 static void blk_trace_free(struct blk_trace *bt)
310 {
311         debugfs_remove(bt->msg_file);
312         debugfs_remove(bt->dropped_file);
313         relay_close(bt->rchan);
314         debugfs_remove(bt->dir);
315         free_percpu(bt->sequence);
316         free_percpu(bt->msg_data);
317         kfree(bt);
318 }
319 
320 static void get_probe_ref(void)
321 {
322         mutex_lock(&blk_probe_mutex);
323         if (++blk_probes_ref == 1)
324                 blk_register_tracepoints();
325         mutex_unlock(&blk_probe_mutex);
326 }
327 
328 static void put_probe_ref(void)
329 {
330         mutex_lock(&blk_probe_mutex);
331         if (!--blk_probes_ref)
332                 blk_unregister_tracepoints();
333         mutex_unlock(&blk_probe_mutex);
334 }
335 
336 static void blk_trace_cleanup(struct blk_trace *bt)
337 {
338         synchronize_rcu();
339         blk_trace_free(bt);
340         put_probe_ref();
341 }
342 
343 static int __blk_trace_remove(struct request_queue *q)
344 {
345         struct blk_trace *bt;
346 
347         bt = xchg(&q->blk_trace, NULL);
348         if (!bt)
349                 return -EINVAL;
350 
351         if (bt->trace_state != Blktrace_running)
352                 blk_trace_cleanup(bt);
353 
354         return 0;
355 }
356 
357 int blk_trace_remove(struct request_queue *q)
358 {
359         int ret;
360 
361         mutex_lock(&q->blk_trace_mutex);
362         ret = __blk_trace_remove(q);
363         mutex_unlock(&q->blk_trace_mutex);
364 
365         return ret;
366 }
367 EXPORT_SYMBOL_GPL(blk_trace_remove);
368 
369 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
370                                 size_t count, loff_t *ppos)
371 {
372         struct blk_trace *bt = filp->private_data;
373         char buf[16];
374 
375         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
376 
377         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
378 }
379 
380 static const struct file_operations blk_dropped_fops = {
381         .owner =        THIS_MODULE,
382         .open =         simple_open,
383         .read =         blk_dropped_read,
384         .llseek =       default_llseek,
385 };
386 
387 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
388                                 size_t count, loff_t *ppos)
389 {
390         char *msg;
391         struct blk_trace *bt;
392 
393         if (count >= BLK_TN_MAX_MSG)
394                 return -EINVAL;
395 
396         msg = memdup_user_nul(buffer, count);
397         if (IS_ERR(msg))
398                 return PTR_ERR(msg);
399 
400         bt = filp->private_data;
401         __trace_note_message(bt, NULL, "%s", msg);
402         kfree(msg);
403 
404         return count;
405 }
406 
407 static const struct file_operations blk_msg_fops = {
408         .owner =        THIS_MODULE,
409         .open =         simple_open,
410         .write =        blk_msg_write,
411         .llseek =       noop_llseek,
412 };
413 
414 /*
415  * Keep track of how many times we encountered a full subbuffer, to aid
416  * the user space app in telling how many lost events there were.
417  */
418 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
419                                      void *prev_subbuf, size_t prev_padding)
420 {
421         struct blk_trace *bt;
422 
423         if (!relay_buf_full(buf))
424                 return 1;
425 
426         bt = buf->chan->private_data;
427         atomic_inc(&bt->dropped);
428         return 0;
429 }
430 
431 static int blk_remove_buf_file_callback(struct dentry *dentry)
432 {
433         debugfs_remove(dentry);
434 
435         return 0;
436 }
437 
438 static struct dentry *blk_create_buf_file_callback(const char *filename,
439                                                    struct dentry *parent,
440                                                    umode_t mode,
441                                                    struct rchan_buf *buf,
442                                                    int *is_global)
443 {
444         return debugfs_create_file(filename, mode, parent, buf,
445                                         &relay_file_operations);
446 }
447 
448 static struct rchan_callbacks blk_relay_callbacks = {
449         .subbuf_start           = blk_subbuf_start_callback,
450         .create_buf_file        = blk_create_buf_file_callback,
451         .remove_buf_file        = blk_remove_buf_file_callback,
452 };
453 
454 static void blk_trace_setup_lba(struct blk_trace *bt,
455                                 struct block_device *bdev)
456 {
457         struct hd_struct *part = NULL;
458 
459         if (bdev)
460                 part = bdev->bd_part;
461 
462         if (part) {
463                 bt->start_lba = part->start_sect;
464                 bt->end_lba = part->start_sect + part->nr_sects;
465         } else {
466                 bt->start_lba = 0;
467                 bt->end_lba = -1ULL;
468         }
469 }
470 
471 /*
472  * Setup everything required to start tracing
473  */
474 static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
475                               struct block_device *bdev,
476                               struct blk_user_trace_setup *buts)
477 {
478         struct blk_trace *bt = NULL;
479         struct dentry *dir = NULL;
480         int ret;
481 
482         if (!buts->buf_size || !buts->buf_nr)
483                 return -EINVAL;
484 
485         if (!blk_debugfs_root)
486                 return -ENOENT;
487 
488         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
489         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
490 
491         /*
492          * some device names have larger paths - convert the slashes
493          * to underscores for this to work as expected
494          */
495         strreplace(buts->name, '/', '_');
496 
497         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
498         if (!bt)
499                 return -ENOMEM;
500 
501         ret = -ENOMEM;
502         bt->sequence = alloc_percpu(unsigned long);
503         if (!bt->sequence)
504                 goto err;
505 
506         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
507         if (!bt->msg_data)
508                 goto err;
509 
510         ret = -ENOENT;
511 
512         dir = debugfs_lookup(buts->name, blk_debugfs_root);
513         if (!dir)
514                 bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);
515 
516         bt->dev = dev;
517         atomic_set(&bt->dropped, 0);
518         INIT_LIST_HEAD(&bt->running_list);
519 
520         ret = -EIO;
521         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
522                                                &blk_dropped_fops);
523 
524         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
525 
526         bt->rchan = relay_open("trace", dir, buts->buf_size,
527                                 buts->buf_nr, &blk_relay_callbacks, bt);
528         if (!bt->rchan)
529                 goto err;
530 
531         bt->act_mask = buts->act_mask;
532         if (!bt->act_mask)
533                 bt->act_mask = (u16) -1;
534 
535         blk_trace_setup_lba(bt, bdev);
536 
537         /* overwrite with user settings */
538         if (buts->start_lba)
539                 bt->start_lba = buts->start_lba;
540         if (buts->end_lba)
541                 bt->end_lba = buts->end_lba;
542 
543         bt->pid = buts->pid;
544         bt->trace_state = Blktrace_setup;
545 
546         ret = -EBUSY;
547         if (cmpxchg(&q->blk_trace, NULL, bt))
548                 goto err;
549 
550         get_probe_ref();
551 
552         ret = 0;
553 err:
554         if (dir && !bt->dir)
555                 dput(dir);
556         if (ret)
557                 blk_trace_free(bt);
558         return ret;
559 }
560 
561 static int __blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
562                              struct block_device *bdev, char __user *arg)
563 {
564         struct blk_user_trace_setup buts;
565         int ret;
566 
567         ret = copy_from_user(&buts, arg, sizeof(buts));
568         if (ret)
569                 return -EFAULT;
570 
571         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
572         if (ret)
573                 return ret;
574 
575         if (copy_to_user(arg, &buts, sizeof(buts))) {
576                 __blk_trace_remove(q);
577                 return -EFAULT;
578         }
579         return 0;
580 }
581 
582 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
583                     struct block_device *bdev,
584                     char __user *arg)
585 {
586         int ret;
587 
588         mutex_lock(&q->blk_trace_mutex);
589         ret = __blk_trace_setup(q, name, dev, bdev, arg);
590         mutex_unlock(&q->blk_trace_mutex);
591 
592         return ret;
593 }
594 EXPORT_SYMBOL_GPL(blk_trace_setup);
595 
596 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
597 static int compat_blk_trace_setup(struct request_queue *q, char *name,
598                                   dev_t dev, struct block_device *bdev,
599                                   char __user *arg)
600 {
601         struct blk_user_trace_setup buts;
602         struct compat_blk_user_trace_setup cbuts;
603         int ret;
604 
605         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
606                 return -EFAULT;
607 
608         buts = (struct blk_user_trace_setup) {
609                 .act_mask = cbuts.act_mask,
610                 .buf_size = cbuts.buf_size,
611                 .buf_nr = cbuts.buf_nr,
612                 .start_lba = cbuts.start_lba,
613                 .end_lba = cbuts.end_lba,
614                 .pid = cbuts.pid,
615         };
616 
617         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
618         if (ret)
619                 return ret;
620 
621         if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
622                 __blk_trace_remove(q);
623                 return -EFAULT;
624         }
625 
626         return 0;
627 }
628 #endif
629 
630 static int __blk_trace_startstop(struct request_queue *q, int start)
631 {
632         int ret;
633         struct blk_trace *bt;
634 
635         bt = rcu_dereference_protected(q->blk_trace,
636                                        lockdep_is_held(&q->blk_trace_mutex));
637         if (bt == NULL)
638                 return -EINVAL;
639 
640         /*
641          * For starting a trace, we can transition from a setup or stopped
642          * trace. For stopping a trace, the state must be running
643          */
644         ret = -EINVAL;
645         if (start) {
646                 if (bt->trace_state == Blktrace_setup ||
647                     bt->trace_state == Blktrace_stopped) {
648                         blktrace_seq++;
649                         smp_mb();
650                         bt->trace_state = Blktrace_running;
651                         spin_lock_irq(&running_trace_lock);
652                         list_add(&bt->running_list, &running_trace_list);
653                         spin_unlock_irq(&running_trace_lock);
654 
655                         trace_note_time(bt);
656                         ret = 0;
657                 }
658         } else {
659                 if (bt->trace_state == Blktrace_running) {
660                         bt->trace_state = Blktrace_stopped;
661                         spin_lock_irq(&running_trace_lock);
662                         list_del_init(&bt->running_list);
663                         spin_unlock_irq(&running_trace_lock);
664                         relay_flush(bt->rchan);
665                         ret = 0;
666                 }
667         }
668 
669         return ret;
670 }
671 
672 int blk_trace_startstop(struct request_queue *q, int start)
673 {
674         int ret;
675 
676         mutex_lock(&q->blk_trace_mutex);
677         ret = __blk_trace_startstop(q, start);
678         mutex_unlock(&q->blk_trace_mutex);
679 
680         return ret;
681 }
682 EXPORT_SYMBOL_GPL(blk_trace_startstop);
683 
684 /*
685  * When reading or writing the blktrace sysfs files, the references to the
686  * opened sysfs or device files should prevent the underlying block device
687  * from being removed. So no further delete protection is really needed.
688  */
689 
690 /**
691  * blk_trace_ioctl: - handle the ioctls associated with tracing
692  * @bdev:       the block device
693  * @cmd:        the ioctl cmd
694  * @arg:        the argument data, if any
695  *
696  **/
697 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
698 {
699         struct request_queue *q;
700         int ret, start = 0;
701         char b[BDEVNAME_SIZE];
702 
703         q = bdev_get_queue(bdev);
704         if (!q)
705                 return -ENXIO;
706 
707         mutex_lock(&q->blk_trace_mutex);
708 
709         switch (cmd) {
710         case BLKTRACESETUP:
711                 bdevname(bdev, b);
712                 ret = __blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
713                 break;
714 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
715         case BLKTRACESETUP32:
716                 bdevname(bdev, b);
717                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
718                 break;
719 #endif
720         case BLKTRACESTART:
721                 start = 1;
722                 /* fall through */
723         case BLKTRACESTOP:
724                 ret = __blk_trace_startstop(q, start);
725                 break;
726         case BLKTRACETEARDOWN:
727                 ret = __blk_trace_remove(q);
728                 break;
729         default:
730                 ret = -ENOTTY;
731                 break;
732         }
733 
734         mutex_unlock(&q->blk_trace_mutex);
735         return ret;
736 }
737 
738 /**
739  * blk_trace_shutdown: - stop and cleanup trace structures
740  * @q:    the request queue associated with the device
741  *
742  **/
743 void blk_trace_shutdown(struct request_queue *q)
744 {
745         mutex_lock(&q->blk_trace_mutex);
746         if (rcu_dereference_protected(q->blk_trace,
747                                       lockdep_is_held(&q->blk_trace_mutex))) {
748                 __blk_trace_startstop(q, 0);
749                 __blk_trace_remove(q);
750         }
751 
752         mutex_unlock(&q->blk_trace_mutex);
753 }
754 
755 #ifdef CONFIG_BLK_CGROUP
756 static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
757 {
758         struct blk_trace *bt;
759 
760         /* We don't use the 'bt' value here except as an optimization... */
761         bt = rcu_dereference_protected(q->blk_trace, 1);
762         if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
763                 return 0;
764 
765         if (!bio->bi_blkg)
766                 return 0;
767         return cgroup_id(bio_blkcg(bio)->css.cgroup);
768 }
769 #else
770 u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
771 {
772         return 0;
773 }
774 #endif
775 
776 static u64
777 blk_trace_request_get_cgid(struct request_queue *q, struct request *rq)
778 {
779         if (!rq->bio)
780                 return 0;
781         /* Use the first bio */
782         return blk_trace_bio_get_cgid(q, rq->bio);
783 }
784 
785 /*
786  * blktrace probes
787  */
788 
789 /**
790  * blk_add_trace_rq - Add a trace for a request oriented action
791  * @rq:         the source request
792  * @error:      return status to log
793  * @nr_bytes:   number of completed bytes
794  * @what:       the action
795  * @cgid:       the cgroup info
796  *
797  * Description:
798  *     Records an action against a request. Will log the bio offset + size.
799  *
800  **/
801 static void blk_add_trace_rq(struct request *rq, int error,
802                              unsigned int nr_bytes, u32 what, u64 cgid)
803 {
804         struct blk_trace *bt;
805 
806         rcu_read_lock();
807         bt = rcu_dereference(rq->q->blk_trace);
808         if (likely(!bt)) {
809                 rcu_read_unlock();
810                 return;
811         }
812 
813         if (blk_rq_is_passthrough(rq))
814                 what |= BLK_TC_ACT(BLK_TC_PC);
815         else
816                 what |= BLK_TC_ACT(BLK_TC_FS);
817 
818         __blk_add_trace(bt, blk_rq_trace_sector(rq), nr_bytes, req_op(rq),
819                         rq->cmd_flags, what, error, 0, NULL, cgid);
820         rcu_read_unlock();
821 }
822 
823 static void blk_add_trace_rq_insert(void *ignore,
824                                     struct request_queue *q, struct request *rq)
825 {
826         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_INSERT,
827                          blk_trace_request_get_cgid(q, rq));
828 }
829 
830 static void blk_add_trace_rq_issue(void *ignore,
831                                    struct request_queue *q, struct request *rq)
832 {
833         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_ISSUE,
834                          blk_trace_request_get_cgid(q, rq));
835 }
836 
837 static void blk_add_trace_rq_requeue(void *ignore,
838                                      struct request_queue *q,
839                                      struct request *rq)
840 {
841         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_REQUEUE,
842                          blk_trace_request_get_cgid(q, rq));
843 }
844 
845 static void blk_add_trace_rq_complete(void *ignore, struct request *rq,
846                         int error, unsigned int nr_bytes)
847 {
848         blk_add_trace_rq(rq, error, nr_bytes, BLK_TA_COMPLETE,
849                          blk_trace_request_get_cgid(rq->q, rq));
850 }
851 
852 /**
853  * blk_add_trace_bio - Add a trace for a bio oriented action
854  * @q:          queue the io is for
855  * @bio:        the source bio
856  * @what:       the action
857  * @error:      error, if any
858  *
859  * Description:
860  *     Records an action against a bio. Will log the bio offset + size.
861  *
862  **/
863 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
864                               u32 what, int error)
865 {
866         struct blk_trace *bt;
867 
868         rcu_read_lock();
869         bt = rcu_dereference(q->blk_trace);
870         if (likely(!bt)) {
871                 rcu_read_unlock();
872                 return;
873         }
874 
875         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
876                         bio_op(bio), bio->bi_opf, what, error, 0, NULL,
877                         blk_trace_bio_get_cgid(q, bio));
878         rcu_read_unlock();
879 }
880 
881 static void blk_add_trace_bio_bounce(void *ignore,
882                                      struct request_queue *q, struct bio *bio)
883 {
884         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
885 }
886 
887 static void blk_add_trace_bio_complete(void *ignore,
888                                        struct request_queue *q, struct bio *bio,
889                                        int error)
890 {
891         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
892 }
893 
894 static void blk_add_trace_bio_backmerge(void *ignore,
895                                         struct request_queue *q,
896                                         struct request *rq,
897                                         struct bio *bio)
898 {
899         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
900 }
901 
902 static void blk_add_trace_bio_frontmerge(void *ignore,
903                                          struct request_queue *q,
904                                          struct request *rq,
905                                          struct bio *bio)
906 {
907         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
908 }
909 
910 static void blk_add_trace_bio_queue(void *ignore,
911                                     struct request_queue *q, struct bio *bio)
912 {
913         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
914 }
915 
916 static void blk_add_trace_getrq(void *ignore,
917                                 struct request_queue *q,
918                                 struct bio *bio, int rw)
919 {
920         if (bio)
921                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
922         else {
923                 struct blk_trace *bt;
924 
925                 rcu_read_lock();
926                 bt = rcu_dereference(q->blk_trace);
927                 if (bt)
928                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_GETRQ, 0, 0,
929                                         NULL, 0);
930                 rcu_read_unlock();
931         }
932 }
933 
934 
935 static void blk_add_trace_sleeprq(void *ignore,
936                                   struct request_queue *q,
937                                   struct bio *bio, int rw)
938 {
939         if (bio)
940                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
941         else {
942                 struct blk_trace *bt;
943 
944                 rcu_read_lock();
945                 bt = rcu_dereference(q->blk_trace);
946                 if (bt)
947                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_SLEEPRQ,
948                                         0, 0, NULL, 0);
949                 rcu_read_unlock();
950         }
951 }
952 
953 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
954 {
955         struct blk_trace *bt;
956 
957         rcu_read_lock();
958         bt = rcu_dereference(q->blk_trace);
959         if (bt)
960                 __blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL, 0);
961         rcu_read_unlock();
962 }
963 
964 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
965                                     unsigned int depth, bool explicit)
966 {
967         struct blk_trace *bt;
968 
969         rcu_read_lock();
970         bt = rcu_dereference(q->blk_trace);
971         if (bt) {
972                 __be64 rpdu = cpu_to_be64(depth);
973                 u32 what;
974 
975                 if (explicit)
976                         what = BLK_TA_UNPLUG_IO;
977                 else
978                         what = BLK_TA_UNPLUG_TIMER;
979 
980                 __blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu, 0);
981         }
982         rcu_read_unlock();
983 }
984 
985 static void blk_add_trace_split(void *ignore,
986                                 struct request_queue *q, struct bio *bio,
987                                 unsigned int pdu)
988 {
989         struct blk_trace *bt;
990 
991         rcu_read_lock();
992         bt = rcu_dereference(q->blk_trace);
993         if (bt) {
994                 __be64 rpdu = cpu_to_be64(pdu);
995 
996                 __blk_add_trace(bt, bio->bi_iter.bi_sector,
997                                 bio->bi_iter.bi_size, bio_op(bio), bio->bi_opf,
998                                 BLK_TA_SPLIT, bio->bi_status, sizeof(rpdu),
999                                 &rpdu, blk_trace_bio_get_cgid(q, bio));
1000         }
1001         rcu_read_unlock();
1002 }
1003 
1004 /**
1005  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
1006  * @ignore:     trace callback data parameter (not used)
1007  * @q:          queue the io is for
1008  * @bio:        the source bio
1009  * @dev:        target device
1010  * @from:       source sector
1011  *
1012  * Description:
1013  *     Device mapper or raid target sometimes need to split a bio because
1014  *     it spans a stripe (or similar). Add a trace for that action.
1015  *
1016  **/
1017 static void blk_add_trace_bio_remap(void *ignore,
1018                                     struct request_queue *q, struct bio *bio,
1019                                     dev_t dev, sector_t from)
1020 {
1021         struct blk_trace *bt;
1022         struct blk_io_trace_remap r;
1023 
1024         rcu_read_lock();
1025         bt = rcu_dereference(q->blk_trace);
1026         if (likely(!bt)) {
1027                 rcu_read_unlock();
1028                 return;
1029         }
1030 
1031         r.device_from = cpu_to_be32(dev);
1032         r.device_to   = cpu_to_be32(bio_dev(bio));
1033         r.sector_from = cpu_to_be64(from);
1034 
1035         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
1036                         bio_op(bio), bio->bi_opf, BLK_TA_REMAP, bio->bi_status,
1037                         sizeof(r), &r, blk_trace_bio_get_cgid(q, bio));
1038         rcu_read_unlock();
1039 }
1040 
1041 /**
1042  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
1043  * @ignore:     trace callback data parameter (not used)
1044  * @q:          queue the io is for
1045  * @rq:         the source request
1046  * @dev:        target device
1047  * @from:       source sector
1048  *
1049  * Description:
1050  *     Device mapper remaps request to other devices.
1051  *     Add a trace for that action.
1052  *
1053  **/
1054 static void blk_add_trace_rq_remap(void *ignore,
1055                                    struct request_queue *q,
1056                                    struct request *rq, dev_t dev,
1057                                    sector_t from)
1058 {
1059         struct blk_trace *bt;
1060         struct blk_io_trace_remap r;
1061 
1062         rcu_read_lock();
1063         bt = rcu_dereference(q->blk_trace);
1064         if (likely(!bt)) {
1065                 rcu_read_unlock();
1066                 return;
1067         }
1068 
1069         r.device_from = cpu_to_be32(dev);
1070         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
1071         r.sector_from = cpu_to_be64(from);
1072 
1073         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
1074                         rq_data_dir(rq), 0, BLK_TA_REMAP, 0,
1075                         sizeof(r), &r, blk_trace_request_get_cgid(q, rq));
1076         rcu_read_unlock();
1077 }
1078 
1079 /**
1080  * blk_add_driver_data - Add binary message with driver-specific data
1081  * @q:          queue the io is for
1082  * @rq:         io request
1083  * @data:       driver-specific data
1084  * @len:        length of driver-specific data
1085  *
1086  * Description:
1087  *     Some drivers might want to write driver-specific data per request.
1088  *
1089  **/
1090 void blk_add_driver_data(struct request_queue *q,
1091                          struct request *rq,
1092                          void *data, size_t len)
1093 {
1094         struct blk_trace *bt;
1095 
1096         rcu_read_lock();
1097         bt = rcu_dereference(q->blk_trace);
1098         if (likely(!bt)) {
1099                 rcu_read_unlock();
1100                 return;
1101         }
1102 
1103         __blk_add_trace(bt, blk_rq_trace_sector(rq), blk_rq_bytes(rq), 0, 0,
1104                                 BLK_TA_DRV_DATA, 0, len, data,
1105                                 blk_trace_request_get_cgid(q, rq));
1106         rcu_read_unlock();
1107 }
1108 EXPORT_SYMBOL_GPL(blk_add_driver_data);
1109 
1110 static void blk_register_tracepoints(void)
1111 {
1112         int ret;
1113 
1114         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1115         WARN_ON(ret);
1116         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1117         WARN_ON(ret);
1118         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1119         WARN_ON(ret);
1120         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1121         WARN_ON(ret);
1122         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1123         WARN_ON(ret);
1124         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1125         WARN_ON(ret);
1126         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1127         WARN_ON(ret);
1128         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1129         WARN_ON(ret);
1130         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1131         WARN_ON(ret);
1132         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1133         WARN_ON(ret);
1134         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1135         WARN_ON(ret);
1136         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1137         WARN_ON(ret);
1138         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1139         WARN_ON(ret);
1140         ret = register_trace_block_split(blk_add_trace_split, NULL);
1141         WARN_ON(ret);
1142         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1143         WARN_ON(ret);
1144         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1145         WARN_ON(ret);
1146 }
1147 
1148 static void blk_unregister_tracepoints(void)
1149 {
1150         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1151         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1152         unregister_trace_block_split(blk_add_trace_split, NULL);
1153         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1154         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1155         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1156         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1157         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1158         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1159         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1160         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1161         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1162         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1163         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1164         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1165         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1166 
1167         tracepoint_synchronize_unregister();
1168 }
1169 
1170 /*
1171  * struct blk_io_tracer formatting routines
1172  */
1173 
1174 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1175 {
1176         int i = 0;
1177         int tc = t->action >> BLK_TC_SHIFT;
1178 
1179         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1180                 rwbs[i++] = 'N';
1181                 goto out;
1182         }
1183 
1184         if (tc & BLK_TC_FLUSH)
1185                 rwbs[i++] = 'F';
1186 
1187         if (tc & BLK_TC_DISCARD)
1188                 rwbs[i++] = 'D';
1189         else if (tc & BLK_TC_WRITE)
1190                 rwbs[i++] = 'W';
1191         else if (t->bytes)
1192                 rwbs[i++] = 'R';
1193         else
1194                 rwbs[i++] = 'N';
1195 
1196         if (tc & BLK_TC_FUA)
1197                 rwbs[i++] = 'F';
1198         if (tc & BLK_TC_AHEAD)
1199                 rwbs[i++] = 'A';
1200         if (tc & BLK_TC_SYNC)
1201                 rwbs[i++] = 'S';
1202         if (tc & BLK_TC_META)
1203                 rwbs[i++] = 'M';
1204 out:
1205         rwbs[i] = '\0';
1206 }
1207 
1208 static inline
1209 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1210 {
1211         return (const struct blk_io_trace *)ent;
1212 }
1213 
1214 static inline const void *pdu_start(const struct trace_entry *ent, bool has_cg)
1215 {
1216         return (void *)(te_blk_io_trace(ent) + 1) + (has_cg ? sizeof(u64) : 0);
1217 }
1218 
1219 static inline u64 t_cgid(const struct trace_entry *ent)
1220 {
1221         return *(u64 *)(te_blk_io_trace(ent) + 1);
1222 }
1223 
1224 static inline int pdu_real_len(const struct trace_entry *ent, bool has_cg)
1225 {
1226         return te_blk_io_trace(ent)->pdu_len - (has_cg ? sizeof(u64) : 0);
1227 }
1228 
1229 static inline u32 t_action(const struct trace_entry *ent)
1230 {
1231         return te_blk_io_trace(ent)->action;
1232 }
1233 
1234 static inline u32 t_bytes(const struct trace_entry *ent)
1235 {
1236         return te_blk_io_trace(ent)->bytes;
1237 }
1238 
1239 static inline u32 t_sec(const struct trace_entry *ent)
1240 {
1241         return te_blk_io_trace(ent)->bytes >> 9;
1242 }
1243 
1244 static inline unsigned long long t_sector(const struct trace_entry *ent)
1245 {
1246         return te_blk_io_trace(ent)->sector;
1247 }
1248 
1249 static inline __u16 t_error(const struct trace_entry *ent)
1250 {
1251         return te_blk_io_trace(ent)->error;
1252 }
1253 
1254 static __u64 get_pdu_int(const struct trace_entry *ent, bool has_cg)
1255 {
1256         const __u64 *val = pdu_start(ent, has_cg);
1257         return be64_to_cpu(*val);
1258 }
1259 
1260 static void get_pdu_remap(const struct trace_entry *ent,
1261                           struct blk_io_trace_remap *r, bool has_cg)
1262 {
1263         const struct blk_io_trace_remap *__r = pdu_start(ent, has_cg);
1264         __u64 sector_from = __r->sector_from;
1265 
1266         r->device_from = be32_to_cpu(__r->device_from);
1267         r->device_to   = be32_to_cpu(__r->device_to);
1268         r->sector_from = be64_to_cpu(sector_from);
1269 }
1270 
1271 typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act,
1272         bool has_cg);
1273 
1274 static void blk_log_action_classic(struct trace_iterator *iter, const char *act,
1275         bool has_cg)
1276 {
1277         char rwbs[RWBS_LEN];
1278         unsigned long long ts  = iter->ts;
1279         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1280         unsigned secs          = (unsigned long)ts;
1281         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1282 
1283         fill_rwbs(rwbs, t);
1284 
1285         trace_seq_printf(&iter->seq,
1286                          "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1287                          MAJOR(t->device), MINOR(t->device), iter->cpu,
1288                          secs, nsec_rem, iter->ent->pid, act, rwbs);
1289 }
1290 
1291 static void blk_log_action(struct trace_iterator *iter, const char *act,
1292         bool has_cg)
1293 {
1294         char rwbs[RWBS_LEN];
1295         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1296 
1297         fill_rwbs(rwbs, t);
1298         if (has_cg) {
1299                 u64 id = t_cgid(iter->ent);
1300 
1301                 if (blk_tracer_flags.val & TRACE_BLK_OPT_CGNAME) {
1302                         char blkcg_name_buf[NAME_MAX + 1] = "<...>";
1303 
1304                         cgroup_path_from_kernfs_id(id, blkcg_name_buf,
1305                                 sizeof(blkcg_name_buf));
1306                         trace_seq_printf(&iter->seq, "%3d,%-3d %s %2s %3s ",
1307                                  MAJOR(t->device), MINOR(t->device),
1308                                  blkcg_name_buf, act, rwbs);
1309                 } else {
1310                         /*
1311                          * The cgid portion used to be "INO,GEN".  Userland
1312                          * builds a FILEID_INO32_GEN fid out of them and
1313                          * opens the cgroup using open_by_handle_at(2).
1314                          * While 32bit ino setups are still the same, 64bit
1315                          * ones now use the 64bit ino as the whole ID and
1316                          * no longer use generation.
1317                          *
1318                          * Regarldess of the content, always output
1319                          * "LOW32,HIGH32" so that FILEID_INO32_GEN fid can
1320                          * be mapped back to @id on both 64 and 32bit ino
1321                          * setups.  See __kernfs_fh_to_dentry().
1322                          */
1323                         trace_seq_printf(&iter->seq,
1324                                  "%3d,%-3d %llx,%-llx %2s %3s ",
1325                                  MAJOR(t->device), MINOR(t->device),
1326                                  id & U32_MAX, id >> 32, act, rwbs);
1327                 }
1328         } else
1329                 trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1330                                  MAJOR(t->device), MINOR(t->device), act, rwbs);
1331 }
1332 
1333 static void blk_log_dump_pdu(struct trace_seq *s,
1334         const struct trace_entry *ent, bool has_cg)
1335 {
1336         const unsigned char *pdu_buf;
1337         int pdu_len;
1338         int i, end;
1339 
1340         pdu_buf = pdu_start(ent, has_cg);
1341         pdu_len = pdu_real_len(ent, has_cg);
1342 
1343         if (!pdu_len)
1344                 return;
1345 
1346         /* find the last zero that needs to be printed */
1347         for (end = pdu_len - 1; end >= 0; end--)
1348                 if (pdu_buf[end])
1349                         break;
1350         end++;
1351 
1352         trace_seq_putc(s, '(');
1353 
1354         for (i = 0; i < pdu_len; i++) {
1355 
1356                 trace_seq_printf(s, "%s%02x",
1357                                  i == 0 ? "" : " ", pdu_buf[i]);
1358 
1359                 /*
1360                  * stop when the rest is just zeroes and indicate so
1361                  * with a ".." appended
1362                  */
1363                 if (i == end && end != pdu_len - 1) {
1364                         trace_seq_puts(s, " ..) ");
1365                         return;
1366                 }
1367         }
1368 
1369         trace_seq_puts(s, ") ");
1370 }
1371 
1372 static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1373 {
1374         char cmd[TASK_COMM_LEN];
1375 
1376         trace_find_cmdline(ent->pid, cmd);
1377 
1378         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1379                 trace_seq_printf(s, "%u ", t_bytes(ent));
1380                 blk_log_dump_pdu(s, ent, has_cg);
1381                 trace_seq_printf(s, "[%s]\n", cmd);
1382         } else {
1383                 if (t_sec(ent))
1384                         trace_seq_printf(s, "%llu + %u [%s]\n",
1385                                                 t_sector(ent), t_sec(ent), cmd);
1386                 else
1387                         trace_seq_printf(s, "[%s]\n", cmd);
1388         }
1389 }
1390 
1391 static void blk_log_with_error(struct trace_seq *s,
1392                               const struct trace_entry *ent, bool has_cg)
1393 {
1394         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1395                 blk_log_dump_pdu(s, ent, has_cg);
1396                 trace_seq_printf(s, "[%d]\n", t_error(ent));
1397         } else {
1398                 if (t_sec(ent))
1399                         trace_seq_printf(s, "%llu + %u [%d]\n",
1400                                          t_sector(ent),
1401                                          t_sec(ent), t_error(ent));
1402                 else
1403                         trace_seq_printf(s, "%llu [%d]\n",
1404                                          t_sector(ent), t_error(ent));
1405         }
1406 }
1407 
1408 static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1409 {
1410         struct blk_io_trace_remap r = { .device_from = 0, };
1411 
1412         get_pdu_remap(ent, &r, has_cg);
1413         trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1414                          t_sector(ent), t_sec(ent),
1415                          MAJOR(r.device_from), MINOR(r.device_from),
1416                          (unsigned long long)r.sector_from);
1417 }
1418 
1419 static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1420 {
1421         char cmd[TASK_COMM_LEN];
1422 
1423         trace_find_cmdline(ent->pid, cmd);
1424 
1425         trace_seq_printf(s, "[%s]\n", cmd);
1426 }
1427 
1428 static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1429 {
1430         char cmd[TASK_COMM_LEN];
1431 
1432         trace_find_cmdline(ent->pid, cmd);
1433 
1434         trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent, has_cg));
1435 }
1436 
1437 static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1438 {
1439         char cmd[TASK_COMM_LEN];
1440 
1441         trace_find_cmdline(ent->pid, cmd);
1442 
1443         trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1444                          get_pdu_int(ent, has_cg), cmd);
1445 }
1446 
1447 static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent,
1448                         bool has_cg)
1449 {
1450 
1451         trace_seq_putmem(s, pdu_start(ent, has_cg),
1452                 pdu_real_len(ent, has_cg));
1453         trace_seq_putc(s, '\n');
1454 }
1455 
1456 /*
1457  * struct tracer operations
1458  */
1459 
1460 static void blk_tracer_print_header(struct seq_file *m)
1461 {
1462         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1463                 return;
1464         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1465                     "#  |     |     |           |   |   |\n");
1466 }
1467 
1468 static void blk_tracer_start(struct trace_array *tr)
1469 {
1470         blk_tracer_enabled = true;
1471 }
1472 
1473 static int blk_tracer_init(struct trace_array *tr)
1474 {
1475         blk_tr = tr;
1476         blk_tracer_start(tr);
1477         return 0;
1478 }
1479 
1480 static void blk_tracer_stop(struct trace_array *tr)
1481 {
1482         blk_tracer_enabled = false;
1483 }
1484 
1485 static void blk_tracer_reset(struct trace_array *tr)
1486 {
1487         blk_tracer_stop(tr);
1488 }
1489 
1490 static const struct {
1491         const char *act[2];
1492         void       (*print)(struct trace_seq *s, const struct trace_entry *ent,
1493                             bool has_cg);
1494 } what2act[] = {
1495         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1496         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1497         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1498         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1499         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1500         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1501         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1502         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1503         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1504         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1505         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1506         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1507         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1508         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1509         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1510 };
1511 
1512 static enum print_line_t print_one_line(struct trace_iterator *iter,
1513                                         bool classic)
1514 {
1515         struct trace_array *tr = iter->tr;
1516         struct trace_seq *s = &iter->seq;
1517         const struct blk_io_trace *t;
1518         u16 what;
1519         bool long_act;
1520         blk_log_action_t *log_action;
1521         bool has_cg;
1522 
1523         t          = te_blk_io_trace(iter->ent);
1524         what       = (t->action & ((1 << BLK_TC_SHIFT) - 1)) & ~__BLK_TA_CGROUP;
1525         long_act   = !!(tr->trace_flags & TRACE_ITER_VERBOSE);
1526         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1527         has_cg     = t->action & __BLK_TA_CGROUP;
1528 
1529         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1530                 log_action(iter, long_act ? "message" : "m", has_cg);
1531                 blk_log_msg(s, iter->ent, has_cg);
1532                 return trace_handle_return(s);
1533         }
1534 
1535         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1536                 trace_seq_printf(s, "Unknown action %x\n", what);
1537         else {
1538                 log_action(iter, what2act[what].act[long_act], has_cg);
1539                 what2act[what].print(s, iter->ent, has_cg);
1540         }
1541 
1542         return trace_handle_return(s);
1543 }
1544 
1545 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1546                                                int flags, struct trace_event *event)
1547 {
1548         return print_one_line(iter, false);
1549 }
1550 
1551 static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1552 {
1553         struct trace_seq *s = &iter->seq;
1554         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1555         const int offset = offsetof(struct blk_io_trace, sector);
1556         struct blk_io_trace old = {
1557                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1558                 .time     = iter->ts,
1559         };
1560 
1561         trace_seq_putmem(s, &old, offset);
1562         trace_seq_putmem(s, &t->sector,
1563                          sizeof(old) - offset + t->pdu_len);
1564 }
1565 
1566 static enum print_line_t
1567 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1568                              struct trace_event *event)
1569 {
1570         blk_trace_synthesize_old_trace(iter);
1571 
1572         return trace_handle_return(&iter->seq);
1573 }
1574 
1575 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1576 {
1577         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1578                 return TRACE_TYPE_UNHANDLED;
1579 
1580         return print_one_line(iter, true);
1581 }
1582 
1583 static int
1584 blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1585 {
1586         /* don't output context-info for blk_classic output */
1587         if (bit == TRACE_BLK_OPT_CLASSIC) {
1588                 if (set)
1589                         tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1590                 else
1591                         tr->trace_flags |= TRACE_ITER_CONTEXT_INFO;
1592         }
1593         return 0;
1594 }
1595 
1596 static struct tracer blk_tracer __read_mostly = {
1597         .name           = "blk",
1598         .init           = blk_tracer_init,
1599         .reset          = blk_tracer_reset,
1600         .start          = blk_tracer_start,
1601         .stop           = blk_tracer_stop,
1602         .print_header   = blk_tracer_print_header,
1603         .print_line     = blk_tracer_print_line,
1604         .flags          = &blk_tracer_flags,
1605         .set_flag       = blk_tracer_set_flag,
1606 };
1607 
1608 static struct trace_event_functions trace_blk_event_funcs = {
1609         .trace          = blk_trace_event_print,
1610         .binary         = blk_trace_event_print_binary,
1611 };
1612 
1613 static struct trace_event trace_blk_event = {
1614         .type           = TRACE_BLK,
1615         .funcs          = &trace_blk_event_funcs,
1616 };
1617 
1618 static int __init init_blk_tracer(void)
1619 {
1620         if (!register_trace_event(&trace_blk_event)) {
1621                 pr_warn("Warning: could not register block events\n");
1622                 return 1;
1623         }
1624 
1625         if (register_tracer(&blk_tracer) != 0) {
1626                 pr_warn("Warning: could not register the block tracer\n");
1627                 unregister_trace_event(&trace_blk_event);
1628                 return 1;
1629         }
1630 
1631         return 0;
1632 }
1633 
1634 device_initcall(init_blk_tracer);
1635 
1636 static int blk_trace_remove_queue(struct request_queue *q)
1637 {
1638         struct blk_trace *bt;
1639 
1640         bt = xchg(&q->blk_trace, NULL);
1641         if (bt == NULL)
1642                 return -EINVAL;
1643 
1644         put_probe_ref();
1645         synchronize_rcu();
1646         blk_trace_free(bt);
1647         return 0;
1648 }
1649 
1650 /*
1651  * Setup everything required to start tracing
1652  */
1653 static int blk_trace_setup_queue(struct request_queue *q,
1654                                  struct block_device *bdev)
1655 {
1656         struct blk_trace *bt = NULL;
1657         int ret = -ENOMEM;
1658 
1659         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1660         if (!bt)
1661                 return -ENOMEM;
1662 
1663         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1664         if (!bt->msg_data)
1665                 goto free_bt;
1666 
1667         bt->dev = bdev->bd_dev;
1668         bt->act_mask = (u16)-1;
1669 
1670         blk_trace_setup_lba(bt, bdev);
1671 
1672         ret = -EBUSY;
1673         if (cmpxchg(&q->blk_trace, NULL, bt))
1674                 goto free_bt;
1675 
1676         get_probe_ref();
1677         return 0;
1678 
1679 free_bt:
1680         blk_trace_free(bt);
1681         return ret;
1682 }
1683 
1684 /*
1685  * sysfs interface to enable and configure tracing
1686  */
1687 
1688 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1689                                          struct device_attribute *attr,
1690                                          char *buf);
1691 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1692                                           struct device_attribute *attr,
1693                                           const char *buf, size_t count);
1694 #define BLK_TRACE_DEVICE_ATTR(_name) \
1695         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1696                     sysfs_blk_trace_attr_show, \
1697                     sysfs_blk_trace_attr_store)
1698 
1699 static BLK_TRACE_DEVICE_ATTR(enable);
1700 static BLK_TRACE_DEVICE_ATTR(act_mask);
1701 static BLK_TRACE_DEVICE_ATTR(pid);
1702 static BLK_TRACE_DEVICE_ATTR(start_lba);
1703 static BLK_TRACE_DEVICE_ATTR(end_lba);
1704 
1705 static struct attribute *blk_trace_attrs[] = {
1706         &dev_attr_enable.attr,
1707         &dev_attr_act_mask.attr,
1708         &dev_attr_pid.attr,
1709         &dev_attr_start_lba.attr,
1710         &dev_attr_end_lba.attr,
1711         NULL
1712 };
1713 
1714 struct attribute_group blk_trace_attr_group = {
1715         .name  = "trace",
1716         .attrs = blk_trace_attrs,
1717 };
1718 
1719 static const struct {
1720         int mask;
1721         const char *str;
1722 } mask_maps[] = {
1723         { BLK_TC_READ,          "read"          },
1724         { BLK_TC_WRITE,         "write"         },
1725         { BLK_TC_FLUSH,         "flush"         },
1726         { BLK_TC_SYNC,          "sync"          },
1727         { BLK_TC_QUEUE,         "queue"         },
1728         { BLK_TC_REQUEUE,       "requeue"       },
1729         { BLK_TC_ISSUE,         "issue"         },
1730         { BLK_TC_COMPLETE,      "complete"      },
1731         { BLK_TC_FS,            "fs"            },
1732         { BLK_TC_PC,            "pc"            },
1733         { BLK_TC_NOTIFY,        "notify"        },
1734         { BLK_TC_AHEAD,         "ahead"         },
1735         { BLK_TC_META,          "meta"          },
1736         { BLK_TC_DISCARD,       "discard"       },
1737         { BLK_TC_DRV_DATA,      "drv_data"      },
1738         { BLK_TC_FUA,           "fua"           },
1739 };
1740 
1741 static int blk_trace_str2mask(const char *str)
1742 {
1743         int i;
1744         int mask = 0;
1745         char *buf, *s, *token;
1746 
1747         buf = kstrdup(str, GFP_KERNEL);
1748         if (buf == NULL)
1749                 return -ENOMEM;
1750         s = strstrip(buf);
1751 
1752         while (1) {
1753                 token = strsep(&s, ",");
1754                 if (token == NULL)
1755                         break;
1756 
1757                 if (*token == '\0')
1758                         continue;
1759 
1760                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1761                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1762                                 mask |= mask_maps[i].mask;
1763                                 break;
1764                         }
1765                 }
1766                 if (i == ARRAY_SIZE(mask_maps)) {
1767                         mask = -EINVAL;
1768                         break;
1769                 }
1770         }
1771         kfree(buf);
1772 
1773         return mask;
1774 }
1775 
1776 static ssize_t blk_trace_mask2str(char *buf, int mask)
1777 {
1778         int i;
1779         char *p = buf;
1780 
1781         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1782                 if (mask & mask_maps[i].mask) {
1783                         p += sprintf(p, "%s%s",
1784                                     (p == buf) ? "" : ",", mask_maps[i].str);
1785                 }
1786         }
1787         *p++ = '\n';
1788 
1789         return p - buf;
1790 }
1791 
1792 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1793 {
1794         if (bdev->bd_disk == NULL)
1795                 return NULL;
1796 
1797         return bdev_get_queue(bdev);
1798 }
1799 
1800 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1801                                          struct device_attribute *attr,
1802                                          char *buf)
1803 {
1804         struct hd_struct *p = dev_to_part(dev);
1805         struct request_queue *q;
1806         struct block_device *bdev;
1807         struct blk_trace *bt;
1808         ssize_t ret = -ENXIO;
1809 
1810         bdev = bdget(part_devt(p));
1811         if (bdev == NULL)
1812                 goto out;
1813 
1814         q = blk_trace_get_queue(bdev);
1815         if (q == NULL)
1816                 goto out_bdput;
1817 
1818         mutex_lock(&q->blk_trace_mutex);
1819 
1820         bt = rcu_dereference_protected(q->blk_trace,
1821                                        lockdep_is_held(&q->blk_trace_mutex));
1822         if (attr == &dev_attr_enable) {
1823                 ret = sprintf(buf, "%u\n", !!bt);
1824                 goto out_unlock_bdev;
1825         }
1826 
1827         if (bt == NULL)
1828                 ret = sprintf(buf, "disabled\n");
1829         else if (attr == &dev_attr_act_mask)
1830                 ret = blk_trace_mask2str(buf, bt->act_mask);
1831         else if (attr == &dev_attr_pid)
1832                 ret = sprintf(buf, "%u\n", bt->pid);
1833         else if (attr == &dev_attr_start_lba)
1834                 ret = sprintf(buf, "%llu\n", bt->start_lba);
1835         else if (attr == &dev_attr_end_lba)
1836                 ret = sprintf(buf, "%llu\n", bt->end_lba);
1837 
1838 out_unlock_bdev:
1839         mutex_unlock(&q->blk_trace_mutex);
1840 out_bdput:
1841         bdput(bdev);
1842 out:
1843         return ret;
1844 }
1845 
1846 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1847                                           struct device_attribute *attr,
1848                                           const char *buf, size_t count)
1849 {
1850         struct block_device *bdev;
1851         struct request_queue *q;
1852         struct hd_struct *p;
1853         struct blk_trace *bt;
1854         u64 value;
1855         ssize_t ret = -EINVAL;
1856 
1857         if (count == 0)
1858                 goto out;
1859 
1860         if (attr == &dev_attr_act_mask) {
1861                 if (kstrtoull(buf, 0, &value)) {
1862                         /* Assume it is a list of trace category names */
1863                         ret = blk_trace_str2mask(buf);
1864                         if (ret < 0)
1865                                 goto out;
1866                         value = ret;
1867                 }
1868         } else if (kstrtoull(buf, 0, &value))
1869                 goto out;
1870 
1871         ret = -ENXIO;
1872 
1873         p = dev_to_part(dev);
1874         bdev = bdget(part_devt(p));
1875         if (bdev == NULL)
1876                 goto out;
1877 
1878         q = blk_trace_get_queue(bdev);
1879         if (q == NULL)
1880                 goto out_bdput;
1881 
1882         mutex_lock(&q->blk_trace_mutex);
1883 
1884         bt = rcu_dereference_protected(q->blk_trace,
1885                                        lockdep_is_held(&q->blk_trace_mutex));
1886         if (attr == &dev_attr_enable) {
1887                 if (!!value == !!bt) {
1888                         ret = 0;
1889                         goto out_unlock_bdev;
1890                 }
1891                 if (value)
1892                         ret = blk_trace_setup_queue(q, bdev);
1893                 else
1894                         ret = blk_trace_remove_queue(q);
1895                 goto out_unlock_bdev;
1896         }
1897 
1898         ret = 0;
1899         if (bt == NULL) {
1900                 ret = blk_trace_setup_queue(q, bdev);
1901                 bt = rcu_dereference_protected(q->blk_trace,
1902                                 lockdep_is_held(&q->blk_trace_mutex));
1903         }
1904 
1905         if (ret == 0) {
1906                 if (attr == &dev_attr_act_mask)
1907                         bt->act_mask = value;
1908                 else if (attr == &dev_attr_pid)
1909                         bt->pid = value;
1910                 else if (attr == &dev_attr_start_lba)
1911                         bt->start_lba = value;
1912                 else if (attr == &dev_attr_end_lba)
1913                         bt->end_lba = value;
1914         }
1915 
1916 out_unlock_bdev:
1917         mutex_unlock(&q->blk_trace_mutex);
1918 out_bdput:
1919         bdput(bdev);
1920 out:
1921         return ret ? ret : count;
1922 }
1923 
1924 int blk_trace_init_sysfs(struct device *dev)
1925 {
1926         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1927 }
1928 
1929 void blk_trace_remove_sysfs(struct device *dev)
1930 {
1931         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1932 }
1933 
1934 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1935 
1936 #ifdef CONFIG_EVENT_TRACING
1937 
1938 void blk_fill_rwbs(char *rwbs, unsigned int op, int bytes)
1939 {
1940         int i = 0;
1941 
1942         if (op & REQ_PREFLUSH)
1943                 rwbs[i++] = 'F';
1944 
1945         switch (op & REQ_OP_MASK) {
1946         case REQ_OP_WRITE:
1947         case REQ_OP_WRITE_SAME:
1948                 rwbs[i++] = 'W';
1949                 break;
1950         case REQ_OP_DISCARD:
1951                 rwbs[i++] = 'D';
1952                 break;
1953         case REQ_OP_SECURE_ERASE:
1954                 rwbs[i++] = 'D';
1955                 rwbs[i++] = 'E';
1956                 break;
1957         case REQ_OP_FLUSH:
1958                 rwbs[i++] = 'F';
1959                 break;
1960         case REQ_OP_READ:
1961                 rwbs[i++] = 'R';
1962                 break;
1963         default:
1964                 rwbs[i++] = 'N';
1965         }
1966 
1967         if (op & REQ_FUA)
1968                 rwbs[i++] = 'F';
1969         if (op & REQ_RAHEAD)
1970                 rwbs[i++] = 'A';
1971         if (op & REQ_SYNC)
1972                 rwbs[i++] = 'S';
1973         if (op & REQ_META)
1974                 rwbs[i++] = 'M';
1975 
1976         rwbs[i] = '\0';
1977 }
1978 EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1979 
1980 #endif /* CONFIG_EVENT_TRACING */
1981 
1982 

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