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

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  1 /*
  2  * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU General Public License version 2 as
  6  * published by the Free Software Foundation.
  7  *
  8  * This program is distributed in the hope that it will be useful,
  9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 11  * GNU General Public License for more details.
 12  *
 13  * You should have received a copy of the GNU General Public License
 14  * along with this program; if not, write to the Free Software
 15  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 16  *
 17  */
 18 #include <linux/kernel.h>
 19 #include <linux/blkdev.h>
 20 #include <linux/blktrace_api.h>
 21 #include <linux/percpu.h>
 22 #include <linux/init.h>
 23 #include <linux/mutex.h>
 24 #include <linux/slab.h>
 25 #include <linux/debugfs.h>
 26 #include <linux/export.h>
 27 #include <linux/time.h>
 28 #include <linux/uaccess.h>
 29 #include <linux/list.h>
 30 
 31 #include <trace/events/block.h>
 32 
 33 #include "trace_output.h"
 34 
 35 #ifdef CONFIG_BLK_DEV_IO_TRACE
 36 
 37 static unsigned int blktrace_seq __read_mostly = 1;
 38 
 39 static struct trace_array *blk_tr;
 40 static bool blk_tracer_enabled __read_mostly;
 41 
 42 static LIST_HEAD(running_trace_list);
 43 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock);
 44 
 45 /* Select an alternative, minimalistic output than the original one */
 46 #define TRACE_BLK_OPT_CLASSIC   0x1
 47 
 48 static struct tracer_opt blk_tracer_opts[] = {
 49         /* Default disable the minimalistic output */
 50         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
 51         { }
 52 };
 53 
 54 static struct tracer_flags blk_tracer_flags = {
 55         .val  = 0,
 56         .opts = blk_tracer_opts,
 57 };
 58 
 59 /* Global reference count of probes */
 60 static atomic_t blk_probes_ref = ATOMIC_INIT(0);
 61 
 62 static void blk_register_tracepoints(void);
 63 static void blk_unregister_tracepoints(void);
 64 
 65 /*
 66  * Send out a notify message.
 67  */
 68 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 69                        const void *data, size_t len)
 70 {
 71         struct blk_io_trace *t;
 72         struct ring_buffer_event *event = NULL;
 73         struct ring_buffer *buffer = NULL;
 74         int pc = 0;
 75         int cpu = smp_processor_id();
 76         bool blk_tracer = blk_tracer_enabled;
 77 
 78         if (blk_tracer) {
 79                 buffer = blk_tr->trace_buffer.buffer;
 80                 pc = preempt_count();
 81                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 82                                                   sizeof(*t) + len,
 83                                                   0, pc);
 84                 if (!event)
 85                         return;
 86                 t = ring_buffer_event_data(event);
 87                 goto record_it;
 88         }
 89 
 90         if (!bt->rchan)
 91                 return;
 92 
 93         t = relay_reserve(bt->rchan, sizeof(*t) + len);
 94         if (t) {
 95                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 96                 t->time = ktime_to_ns(ktime_get());
 97 record_it:
 98                 t->device = bt->dev;
 99                 t->action = action;
100                 t->pid = pid;
101                 t->cpu = cpu;
102                 t->pdu_len = len;
103                 memcpy((void *) t + sizeof(*t), data, len);
104 
105                 if (blk_tracer)
106                         trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
107         }
108 }
109 
110 /*
111  * Send out a notify for this process, if we haven't done so since a trace
112  * started
113  */
114 static void trace_note_tsk(struct task_struct *tsk)
115 {
116         unsigned long flags;
117         struct blk_trace *bt;
118 
119         tsk->btrace_seq = blktrace_seq;
120         spin_lock_irqsave(&running_trace_lock, flags);
121         list_for_each_entry(bt, &running_trace_list, running_list) {
122                 trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm,
123                            sizeof(tsk->comm));
124         }
125         spin_unlock_irqrestore(&running_trace_lock, flags);
126 }
127 
128 static void trace_note_time(struct blk_trace *bt)
129 {
130         struct timespec now;
131         unsigned long flags;
132         u32 words[2];
133 
134         getnstimeofday(&now);
135         words[0] = now.tv_sec;
136         words[1] = now.tv_nsec;
137 
138         local_irq_save(flags);
139         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
140         local_irq_restore(flags);
141 }
142 
143 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
144 {
145         int n;
146         va_list args;
147         unsigned long flags;
148         char *buf;
149 
150         if (unlikely(bt->trace_state != Blktrace_running &&
151                      !blk_tracer_enabled))
152                 return;
153 
154         /*
155          * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
156          * message to the trace.
157          */
158         if (!(bt->act_mask & BLK_TC_NOTIFY))
159                 return;
160 
161         local_irq_save(flags);
162         buf = this_cpu_ptr(bt->msg_data);
163         va_start(args, fmt);
164         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
165         va_end(args);
166 
167         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
168         local_irq_restore(flags);
169 }
170 EXPORT_SYMBOL_GPL(__trace_note_message);
171 
172 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
173                          pid_t pid)
174 {
175         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
176                 return 1;
177         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
178                 return 1;
179         if (bt->pid && pid != bt->pid)
180                 return 1;
181 
182         return 0;
183 }
184 
185 /*
186  * Data direction bit lookup
187  */
188 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
189                                  BLK_TC_ACT(BLK_TC_WRITE) };
190 
191 #define BLK_TC_RAHEAD           BLK_TC_AHEAD
192 
193 /* The ilog2() calls fall out because they're constant */
194 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
195           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
196 
197 /*
198  * The worker for the various blk_add_trace*() types. Fills out a
199  * blk_io_trace structure and places it in a per-cpu subbuffer.
200  */
201 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
202                      int rw, u32 what, int error, int pdu_len, void *pdu_data)
203 {
204         struct task_struct *tsk = current;
205         struct ring_buffer_event *event = NULL;
206         struct ring_buffer *buffer = NULL;
207         struct blk_io_trace *t;
208         unsigned long flags = 0;
209         unsigned long *sequence;
210         pid_t pid;
211         int cpu, pc = 0;
212         bool blk_tracer = blk_tracer_enabled;
213 
214         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
215                 return;
216 
217         what |= ddir_act[rw & WRITE];
218         what |= MASK_TC_BIT(rw, SYNC);
219         what |= MASK_TC_BIT(rw, RAHEAD);
220         what |= MASK_TC_BIT(rw, META);
221         what |= MASK_TC_BIT(rw, DISCARD);
222         what |= MASK_TC_BIT(rw, FLUSH);
223         what |= MASK_TC_BIT(rw, FUA);
224 
225         pid = tsk->pid;
226         if (act_log_check(bt, what, sector, pid))
227                 return;
228         cpu = raw_smp_processor_id();
229 
230         if (blk_tracer) {
231                 tracing_record_cmdline(current);
232 
233                 buffer = blk_tr->trace_buffer.buffer;
234                 pc = preempt_count();
235                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
236                                                   sizeof(*t) + pdu_len,
237                                                   0, pc);
238                 if (!event)
239                         return;
240                 t = ring_buffer_event_data(event);
241                 goto record_it;
242         }
243 
244         if (unlikely(tsk->btrace_seq != blktrace_seq))
245                 trace_note_tsk(tsk);
246 
247         /*
248          * A word about the locking here - we disable interrupts to reserve
249          * some space in the relay per-cpu buffer, to prevent an irq
250          * from coming in and stepping on our toes.
251          */
252         local_irq_save(flags);
253         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
254         if (t) {
255                 sequence = per_cpu_ptr(bt->sequence, cpu);
256 
257                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
258                 t->sequence = ++(*sequence);
259                 t->time = ktime_to_ns(ktime_get());
260 record_it:
261                 /*
262                  * These two are not needed in ftrace as they are in the
263                  * generic trace_entry, filled by tracing_generic_entry_update,
264                  * but for the trace_event->bin() synthesizer benefit we do it
265                  * here too.
266                  */
267                 t->cpu = cpu;
268                 t->pid = pid;
269 
270                 t->sector = sector;
271                 t->bytes = bytes;
272                 t->action = what;
273                 t->device = bt->dev;
274                 t->error = error;
275                 t->pdu_len = pdu_len;
276 
277                 if (pdu_len)
278                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
279 
280                 if (blk_tracer) {
281                         trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
282                         return;
283                 }
284         }
285 
286         local_irq_restore(flags);
287 }
288 
289 static struct dentry *blk_tree_root;
290 static DEFINE_MUTEX(blk_tree_mutex);
291 
292 static void blk_trace_free(struct blk_trace *bt)
293 {
294         debugfs_remove(bt->msg_file);
295         debugfs_remove(bt->dropped_file);
296         relay_close(bt->rchan);
297         debugfs_remove(bt->dir);
298         free_percpu(bt->sequence);
299         free_percpu(bt->msg_data);
300         kfree(bt);
301 }
302 
303 static void blk_trace_cleanup(struct blk_trace *bt)
304 {
305         blk_trace_free(bt);
306         if (atomic_dec_and_test(&blk_probes_ref))
307                 blk_unregister_tracepoints();
308 }
309 
310 int blk_trace_remove(struct request_queue *q)
311 {
312         struct blk_trace *bt;
313 
314         bt = xchg(&q->blk_trace, NULL);
315         if (!bt)
316                 return -EINVAL;
317 
318         if (bt->trace_state != Blktrace_running)
319                 blk_trace_cleanup(bt);
320 
321         return 0;
322 }
323 EXPORT_SYMBOL_GPL(blk_trace_remove);
324 
325 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
326                                 size_t count, loff_t *ppos)
327 {
328         struct blk_trace *bt = filp->private_data;
329         char buf[16];
330 
331         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
332 
333         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
334 }
335 
336 static const struct file_operations blk_dropped_fops = {
337         .owner =        THIS_MODULE,
338         .open =         simple_open,
339         .read =         blk_dropped_read,
340         .llseek =       default_llseek,
341 };
342 
343 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
344                                 size_t count, loff_t *ppos)
345 {
346         char *msg;
347         struct blk_trace *bt;
348 
349         if (count >= BLK_TN_MAX_MSG)
350                 return -EINVAL;
351 
352         msg = memdup_user_nul(buffer, count);
353         if (IS_ERR(msg))
354                 return PTR_ERR(msg);
355 
356         bt = filp->private_data;
357         __trace_note_message(bt, "%s", msg);
358         kfree(msg);
359 
360         return count;
361 }
362 
363 static const struct file_operations blk_msg_fops = {
364         .owner =        THIS_MODULE,
365         .open =         simple_open,
366         .write =        blk_msg_write,
367         .llseek =       noop_llseek,
368 };
369 
370 /*
371  * Keep track of how many times we encountered a full subbuffer, to aid
372  * the user space app in telling how many lost events there were.
373  */
374 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
375                                      void *prev_subbuf, size_t prev_padding)
376 {
377         struct blk_trace *bt;
378 
379         if (!relay_buf_full(buf))
380                 return 1;
381 
382         bt = buf->chan->private_data;
383         atomic_inc(&bt->dropped);
384         return 0;
385 }
386 
387 static int blk_remove_buf_file_callback(struct dentry *dentry)
388 {
389         debugfs_remove(dentry);
390 
391         return 0;
392 }
393 
394 static struct dentry *blk_create_buf_file_callback(const char *filename,
395                                                    struct dentry *parent,
396                                                    umode_t mode,
397                                                    struct rchan_buf *buf,
398                                                    int *is_global)
399 {
400         return debugfs_create_file(filename, mode, parent, buf,
401                                         &relay_file_operations);
402 }
403 
404 static struct rchan_callbacks blk_relay_callbacks = {
405         .subbuf_start           = blk_subbuf_start_callback,
406         .create_buf_file        = blk_create_buf_file_callback,
407         .remove_buf_file        = blk_remove_buf_file_callback,
408 };
409 
410 static void blk_trace_setup_lba(struct blk_trace *bt,
411                                 struct block_device *bdev)
412 {
413         struct hd_struct *part = NULL;
414 
415         if (bdev)
416                 part = bdev->bd_part;
417 
418         if (part) {
419                 bt->start_lba = part->start_sect;
420                 bt->end_lba = part->start_sect + part->nr_sects;
421         } else {
422                 bt->start_lba = 0;
423                 bt->end_lba = -1ULL;
424         }
425 }
426 
427 /*
428  * Setup everything required to start tracing
429  */
430 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
431                        struct block_device *bdev,
432                        struct blk_user_trace_setup *buts)
433 {
434         struct blk_trace *bt = NULL;
435         struct dentry *dir = NULL;
436         int ret;
437 
438         if (!buts->buf_size || !buts->buf_nr)
439                 return -EINVAL;
440 
441         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
442         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
443 
444         /*
445          * some device names have larger paths - convert the slashes
446          * to underscores for this to work as expected
447          */
448         strreplace(buts->name, '/', '_');
449 
450         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
451         if (!bt)
452                 return -ENOMEM;
453 
454         ret = -ENOMEM;
455         bt->sequence = alloc_percpu(unsigned long);
456         if (!bt->sequence)
457                 goto err;
458 
459         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
460         if (!bt->msg_data)
461                 goto err;
462 
463         ret = -ENOENT;
464 
465         mutex_lock(&blk_tree_mutex);
466         if (!blk_tree_root) {
467                 blk_tree_root = debugfs_create_dir("block", NULL);
468                 if (!blk_tree_root) {
469                         mutex_unlock(&blk_tree_mutex);
470                         goto err;
471                 }
472         }
473         mutex_unlock(&blk_tree_mutex);
474 
475         dir = debugfs_create_dir(buts->name, blk_tree_root);
476 
477         if (!dir)
478                 goto err;
479 
480         bt->dir = dir;
481         bt->dev = dev;
482         atomic_set(&bt->dropped, 0);
483         INIT_LIST_HEAD(&bt->running_list);
484 
485         ret = -EIO;
486         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
487                                                &blk_dropped_fops);
488         if (!bt->dropped_file)
489                 goto err;
490 
491         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
492         if (!bt->msg_file)
493                 goto err;
494 
495         bt->rchan = relay_open("trace", dir, buts->buf_size,
496                                 buts->buf_nr, &blk_relay_callbacks, bt);
497         if (!bt->rchan)
498                 goto err;
499 
500         bt->act_mask = buts->act_mask;
501         if (!bt->act_mask)
502                 bt->act_mask = (u16) -1;
503 
504         blk_trace_setup_lba(bt, bdev);
505 
506         /* overwrite with user settings */
507         if (buts->start_lba)
508                 bt->start_lba = buts->start_lba;
509         if (buts->end_lba)
510                 bt->end_lba = buts->end_lba;
511 
512         bt->pid = buts->pid;
513         bt->trace_state = Blktrace_setup;
514 
515         ret = -EBUSY;
516         if (cmpxchg(&q->blk_trace, NULL, bt))
517                 goto err;
518 
519         if (atomic_inc_return(&blk_probes_ref) == 1)
520                 blk_register_tracepoints();
521 
522         return 0;
523 err:
524         blk_trace_free(bt);
525         return ret;
526 }
527 
528 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
529                     struct block_device *bdev,
530                     char __user *arg)
531 {
532         struct blk_user_trace_setup buts;
533         int ret;
534 
535         ret = copy_from_user(&buts, arg, sizeof(buts));
536         if (ret)
537                 return -EFAULT;
538 
539         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
540         if (ret)
541                 return ret;
542 
543         if (copy_to_user(arg, &buts, sizeof(buts))) {
544                 blk_trace_remove(q);
545                 return -EFAULT;
546         }
547         return 0;
548 }
549 EXPORT_SYMBOL_GPL(blk_trace_setup);
550 
551 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
552 static int compat_blk_trace_setup(struct request_queue *q, char *name,
553                                   dev_t dev, struct block_device *bdev,
554                                   char __user *arg)
555 {
556         struct blk_user_trace_setup buts;
557         struct compat_blk_user_trace_setup cbuts;
558         int ret;
559 
560         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
561                 return -EFAULT;
562 
563         buts = (struct blk_user_trace_setup) {
564                 .act_mask = cbuts.act_mask,
565                 .buf_size = cbuts.buf_size,
566                 .buf_nr = cbuts.buf_nr,
567                 .start_lba = cbuts.start_lba,
568                 .end_lba = cbuts.end_lba,
569                 .pid = cbuts.pid,
570         };
571 
572         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
573         if (ret)
574                 return ret;
575 
576         if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
577                 blk_trace_remove(q);
578                 return -EFAULT;
579         }
580 
581         return 0;
582 }
583 #endif
584 
585 int blk_trace_startstop(struct request_queue *q, int start)
586 {
587         int ret;
588         struct blk_trace *bt = q->blk_trace;
589 
590         if (bt == NULL)
591                 return -EINVAL;
592 
593         /*
594          * For starting a trace, we can transition from a setup or stopped
595          * trace. For stopping a trace, the state must be running
596          */
597         ret = -EINVAL;
598         if (start) {
599                 if (bt->trace_state == Blktrace_setup ||
600                     bt->trace_state == Blktrace_stopped) {
601                         blktrace_seq++;
602                         smp_mb();
603                         bt->trace_state = Blktrace_running;
604                         spin_lock_irq(&running_trace_lock);
605                         list_add(&bt->running_list, &running_trace_list);
606                         spin_unlock_irq(&running_trace_lock);
607 
608                         trace_note_time(bt);
609                         ret = 0;
610                 }
611         } else {
612                 if (bt->trace_state == Blktrace_running) {
613                         bt->trace_state = Blktrace_stopped;
614                         spin_lock_irq(&running_trace_lock);
615                         list_del_init(&bt->running_list);
616                         spin_unlock_irq(&running_trace_lock);
617                         relay_flush(bt->rchan);
618                         ret = 0;
619                 }
620         }
621 
622         return ret;
623 }
624 EXPORT_SYMBOL_GPL(blk_trace_startstop);
625 
626 /**
627  * blk_trace_ioctl: - handle the ioctls associated with tracing
628  * @bdev:       the block device
629  * @cmd:        the ioctl cmd
630  * @arg:        the argument data, if any
631  *
632  **/
633 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
634 {
635         struct request_queue *q;
636         int ret, start = 0;
637         char b[BDEVNAME_SIZE];
638 
639         q = bdev_get_queue(bdev);
640         if (!q)
641                 return -ENXIO;
642 
643         mutex_lock(&bdev->bd_mutex);
644 
645         switch (cmd) {
646         case BLKTRACESETUP:
647                 bdevname(bdev, b);
648                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
649                 break;
650 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
651         case BLKTRACESETUP32:
652                 bdevname(bdev, b);
653                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
654                 break;
655 #endif
656         case BLKTRACESTART:
657                 start = 1;
658         case BLKTRACESTOP:
659                 ret = blk_trace_startstop(q, start);
660                 break;
661         case BLKTRACETEARDOWN:
662                 ret = blk_trace_remove(q);
663                 break;
664         default:
665                 ret = -ENOTTY;
666                 break;
667         }
668 
669         mutex_unlock(&bdev->bd_mutex);
670         return ret;
671 }
672 
673 /**
674  * blk_trace_shutdown: - stop and cleanup trace structures
675  * @q:    the request queue associated with the device
676  *
677  **/
678 void blk_trace_shutdown(struct request_queue *q)
679 {
680         if (q->blk_trace) {
681                 blk_trace_startstop(q, 0);
682                 blk_trace_remove(q);
683         }
684 }
685 
686 /*
687  * blktrace probes
688  */
689 
690 /**
691  * blk_add_trace_rq - Add a trace for a request oriented action
692  * @q:          queue the io is for
693  * @rq:         the source request
694  * @nr_bytes:   number of completed bytes
695  * @what:       the action
696  *
697  * Description:
698  *     Records an action against a request. Will log the bio offset + size.
699  *
700  **/
701 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
702                              unsigned int nr_bytes, u32 what)
703 {
704         struct blk_trace *bt = q->blk_trace;
705 
706         if (likely(!bt))
707                 return;
708 
709         if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
710                 what |= BLK_TC_ACT(BLK_TC_PC);
711                 __blk_add_trace(bt, 0, nr_bytes, rq->cmd_flags,
712                                 what, rq->errors, rq->cmd_len, rq->cmd);
713         } else  {
714                 what |= BLK_TC_ACT(BLK_TC_FS);
715                 __blk_add_trace(bt, blk_rq_pos(rq), nr_bytes,
716                                 rq->cmd_flags, what, rq->errors, 0, NULL);
717         }
718 }
719 
720 static void blk_add_trace_rq_abort(void *ignore,
721                                    struct request_queue *q, struct request *rq)
722 {
723         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_ABORT);
724 }
725 
726 static void blk_add_trace_rq_insert(void *ignore,
727                                     struct request_queue *q, struct request *rq)
728 {
729         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_INSERT);
730 }
731 
732 static void blk_add_trace_rq_issue(void *ignore,
733                                    struct request_queue *q, struct request *rq)
734 {
735         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_ISSUE);
736 }
737 
738 static void blk_add_trace_rq_requeue(void *ignore,
739                                      struct request_queue *q,
740                                      struct request *rq)
741 {
742         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_REQUEUE);
743 }
744 
745 static void blk_add_trace_rq_complete(void *ignore,
746                                       struct request_queue *q,
747                                       struct request *rq,
748                                       unsigned int nr_bytes)
749 {
750         blk_add_trace_rq(q, rq, nr_bytes, BLK_TA_COMPLETE);
751 }
752 
753 /**
754  * blk_add_trace_bio - Add a trace for a bio oriented action
755  * @q:          queue the io is for
756  * @bio:        the source bio
757  * @what:       the action
758  * @error:      error, if any
759  *
760  * Description:
761  *     Records an action against a bio. Will log the bio offset + size.
762  *
763  **/
764 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
765                               u32 what, int error)
766 {
767         struct blk_trace *bt = q->blk_trace;
768 
769         if (likely(!bt))
770                 return;
771 
772         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
773                         bio->bi_rw, what, error, 0, NULL);
774 }
775 
776 static void blk_add_trace_bio_bounce(void *ignore,
777                                      struct request_queue *q, struct bio *bio)
778 {
779         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
780 }
781 
782 static void blk_add_trace_bio_complete(void *ignore,
783                                        struct request_queue *q, struct bio *bio,
784                                        int error)
785 {
786         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
787 }
788 
789 static void blk_add_trace_bio_backmerge(void *ignore,
790                                         struct request_queue *q,
791                                         struct request *rq,
792                                         struct bio *bio)
793 {
794         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
795 }
796 
797 static void blk_add_trace_bio_frontmerge(void *ignore,
798                                          struct request_queue *q,
799                                          struct request *rq,
800                                          struct bio *bio)
801 {
802         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
803 }
804 
805 static void blk_add_trace_bio_queue(void *ignore,
806                                     struct request_queue *q, struct bio *bio)
807 {
808         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
809 }
810 
811 static void blk_add_trace_getrq(void *ignore,
812                                 struct request_queue *q,
813                                 struct bio *bio, int rw)
814 {
815         if (bio)
816                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
817         else {
818                 struct blk_trace *bt = q->blk_trace;
819 
820                 if (bt)
821                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
822         }
823 }
824 
825 
826 static void blk_add_trace_sleeprq(void *ignore,
827                                   struct request_queue *q,
828                                   struct bio *bio, int rw)
829 {
830         if (bio)
831                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
832         else {
833                 struct blk_trace *bt = q->blk_trace;
834 
835                 if (bt)
836                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
837                                         0, 0, NULL);
838         }
839 }
840 
841 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
842 {
843         struct blk_trace *bt = q->blk_trace;
844 
845         if (bt)
846                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
847 }
848 
849 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
850                                     unsigned int depth, bool explicit)
851 {
852         struct blk_trace *bt = q->blk_trace;
853 
854         if (bt) {
855                 __be64 rpdu = cpu_to_be64(depth);
856                 u32 what;
857 
858                 if (explicit)
859                         what = BLK_TA_UNPLUG_IO;
860                 else
861                         what = BLK_TA_UNPLUG_TIMER;
862 
863                 __blk_add_trace(bt, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu);
864         }
865 }
866 
867 static void blk_add_trace_split(void *ignore,
868                                 struct request_queue *q, struct bio *bio,
869                                 unsigned int pdu)
870 {
871         struct blk_trace *bt = q->blk_trace;
872 
873         if (bt) {
874                 __be64 rpdu = cpu_to_be64(pdu);
875 
876                 __blk_add_trace(bt, bio->bi_iter.bi_sector,
877                                 bio->bi_iter.bi_size, bio->bi_rw, BLK_TA_SPLIT,
878                                 bio->bi_error, sizeof(rpdu), &rpdu);
879         }
880 }
881 
882 /**
883  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
884  * @ignore:     trace callback data parameter (not used)
885  * @q:          queue the io is for
886  * @bio:        the source bio
887  * @dev:        target device
888  * @from:       source sector
889  *
890  * Description:
891  *     Device mapper or raid target sometimes need to split a bio because
892  *     it spans a stripe (or similar). Add a trace for that action.
893  *
894  **/
895 static void blk_add_trace_bio_remap(void *ignore,
896                                     struct request_queue *q, struct bio *bio,
897                                     dev_t dev, sector_t from)
898 {
899         struct blk_trace *bt = q->blk_trace;
900         struct blk_io_trace_remap r;
901 
902         if (likely(!bt))
903                 return;
904 
905         r.device_from = cpu_to_be32(dev);
906         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
907         r.sector_from = cpu_to_be64(from);
908 
909         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
910                         bio->bi_rw, BLK_TA_REMAP, bio->bi_error,
911                         sizeof(r), &r);
912 }
913 
914 /**
915  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
916  * @ignore:     trace callback data parameter (not used)
917  * @q:          queue the io is for
918  * @rq:         the source request
919  * @dev:        target device
920  * @from:       source sector
921  *
922  * Description:
923  *     Device mapper remaps request to other devices.
924  *     Add a trace for that action.
925  *
926  **/
927 static void blk_add_trace_rq_remap(void *ignore,
928                                    struct request_queue *q,
929                                    struct request *rq, dev_t dev,
930                                    sector_t from)
931 {
932         struct blk_trace *bt = q->blk_trace;
933         struct blk_io_trace_remap r;
934 
935         if (likely(!bt))
936                 return;
937 
938         r.device_from = cpu_to_be32(dev);
939         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
940         r.sector_from = cpu_to_be64(from);
941 
942         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
943                         rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
944                         sizeof(r), &r);
945 }
946 
947 /**
948  * blk_add_driver_data - Add binary message with driver-specific data
949  * @q:          queue the io is for
950  * @rq:         io request
951  * @data:       driver-specific data
952  * @len:        length of driver-specific data
953  *
954  * Description:
955  *     Some drivers might want to write driver-specific data per request.
956  *
957  **/
958 void blk_add_driver_data(struct request_queue *q,
959                          struct request *rq,
960                          void *data, size_t len)
961 {
962         struct blk_trace *bt = q->blk_trace;
963 
964         if (likely(!bt))
965                 return;
966 
967         if (rq->cmd_type == REQ_TYPE_BLOCK_PC)
968                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
969                                 BLK_TA_DRV_DATA, rq->errors, len, data);
970         else
971                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
972                                 BLK_TA_DRV_DATA, rq->errors, len, data);
973 }
974 EXPORT_SYMBOL_GPL(blk_add_driver_data);
975 
976 static void blk_register_tracepoints(void)
977 {
978         int ret;
979 
980         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
981         WARN_ON(ret);
982         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
983         WARN_ON(ret);
984         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
985         WARN_ON(ret);
986         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
987         WARN_ON(ret);
988         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
989         WARN_ON(ret);
990         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
991         WARN_ON(ret);
992         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
993         WARN_ON(ret);
994         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
995         WARN_ON(ret);
996         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
997         WARN_ON(ret);
998         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
999         WARN_ON(ret);
1000         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1001         WARN_ON(ret);
1002         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1003         WARN_ON(ret);
1004         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1005         WARN_ON(ret);
1006         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1007         WARN_ON(ret);
1008         ret = register_trace_block_split(blk_add_trace_split, NULL);
1009         WARN_ON(ret);
1010         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1011         WARN_ON(ret);
1012         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1013         WARN_ON(ret);
1014 }
1015 
1016 static void blk_unregister_tracepoints(void)
1017 {
1018         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1019         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1020         unregister_trace_block_split(blk_add_trace_split, NULL);
1021         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1022         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1023         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1024         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1025         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1026         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1027         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1028         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1029         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1030         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1031         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1032         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1033         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1034         unregister_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
1035 
1036         tracepoint_synchronize_unregister();
1037 }
1038 
1039 /*
1040  * struct blk_io_tracer formatting routines
1041  */
1042 
1043 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1044 {
1045         int i = 0;
1046         int tc = t->action >> BLK_TC_SHIFT;
1047 
1048         if (t->action == BLK_TN_MESSAGE) {
1049                 rwbs[i++] = 'N';
1050                 goto out;
1051         }
1052 
1053         if (tc & BLK_TC_FLUSH)
1054                 rwbs[i++] = 'F';
1055 
1056         if (tc & BLK_TC_DISCARD)
1057                 rwbs[i++] = 'D';
1058         else if (tc & BLK_TC_WRITE)
1059                 rwbs[i++] = 'W';
1060         else if (t->bytes)
1061                 rwbs[i++] = 'R';
1062         else
1063                 rwbs[i++] = 'N';
1064 
1065         if (tc & BLK_TC_FUA)
1066                 rwbs[i++] = 'F';
1067         if (tc & BLK_TC_AHEAD)
1068                 rwbs[i++] = 'A';
1069         if (tc & BLK_TC_SYNC)
1070                 rwbs[i++] = 'S';
1071         if (tc & BLK_TC_META)
1072                 rwbs[i++] = 'M';
1073 out:
1074         rwbs[i] = '\0';
1075 }
1076 
1077 static inline
1078 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1079 {
1080         return (const struct blk_io_trace *)ent;
1081 }
1082 
1083 static inline const void *pdu_start(const struct trace_entry *ent)
1084 {
1085         return te_blk_io_trace(ent) + 1;
1086 }
1087 
1088 static inline u32 t_action(const struct trace_entry *ent)
1089 {
1090         return te_blk_io_trace(ent)->action;
1091 }
1092 
1093 static inline u32 t_bytes(const struct trace_entry *ent)
1094 {
1095         return te_blk_io_trace(ent)->bytes;
1096 }
1097 
1098 static inline u32 t_sec(const struct trace_entry *ent)
1099 {
1100         return te_blk_io_trace(ent)->bytes >> 9;
1101 }
1102 
1103 static inline unsigned long long t_sector(const struct trace_entry *ent)
1104 {
1105         return te_blk_io_trace(ent)->sector;
1106 }
1107 
1108 static inline __u16 t_error(const struct trace_entry *ent)
1109 {
1110         return te_blk_io_trace(ent)->error;
1111 }
1112 
1113 static __u64 get_pdu_int(const struct trace_entry *ent)
1114 {
1115         const __u64 *val = pdu_start(ent);
1116         return be64_to_cpu(*val);
1117 }
1118 
1119 static void get_pdu_remap(const struct trace_entry *ent,
1120                           struct blk_io_trace_remap *r)
1121 {
1122         const struct blk_io_trace_remap *__r = pdu_start(ent);
1123         __u64 sector_from = __r->sector_from;
1124 
1125         r->device_from = be32_to_cpu(__r->device_from);
1126         r->device_to   = be32_to_cpu(__r->device_to);
1127         r->sector_from = be64_to_cpu(sector_from);
1128 }
1129 
1130 typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1131 
1132 static void blk_log_action_classic(struct trace_iterator *iter, const char *act)
1133 {
1134         char rwbs[RWBS_LEN];
1135         unsigned long long ts  = iter->ts;
1136         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1137         unsigned secs          = (unsigned long)ts;
1138         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1139 
1140         fill_rwbs(rwbs, t);
1141 
1142         trace_seq_printf(&iter->seq,
1143                          "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1144                          MAJOR(t->device), MINOR(t->device), iter->cpu,
1145                          secs, nsec_rem, iter->ent->pid, act, rwbs);
1146 }
1147 
1148 static void blk_log_action(struct trace_iterator *iter, const char *act)
1149 {
1150         char rwbs[RWBS_LEN];
1151         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1152 
1153         fill_rwbs(rwbs, t);
1154         trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1155                          MAJOR(t->device), MINOR(t->device), act, rwbs);
1156 }
1157 
1158 static void blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1159 {
1160         const unsigned char *pdu_buf;
1161         int pdu_len;
1162         int i, end;
1163 
1164         pdu_buf = pdu_start(ent);
1165         pdu_len = te_blk_io_trace(ent)->pdu_len;
1166 
1167         if (!pdu_len)
1168                 return;
1169 
1170         /* find the last zero that needs to be printed */
1171         for (end = pdu_len - 1; end >= 0; end--)
1172                 if (pdu_buf[end])
1173                         break;
1174         end++;
1175 
1176         trace_seq_putc(s, '(');
1177 
1178         for (i = 0; i < pdu_len; i++) {
1179 
1180                 trace_seq_printf(s, "%s%02x",
1181                                  i == 0 ? "" : " ", pdu_buf[i]);
1182 
1183                 /*
1184                  * stop when the rest is just zeroes and indicate so
1185                  * with a ".." appended
1186                  */
1187                 if (i == end && end != pdu_len - 1) {
1188                         trace_seq_puts(s, " ..) ");
1189                         return;
1190                 }
1191         }
1192 
1193         trace_seq_puts(s, ") ");
1194 }
1195 
1196 static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1197 {
1198         char cmd[TASK_COMM_LEN];
1199 
1200         trace_find_cmdline(ent->pid, cmd);
1201 
1202         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1203                 trace_seq_printf(s, "%u ", t_bytes(ent));
1204                 blk_log_dump_pdu(s, ent);
1205                 trace_seq_printf(s, "[%s]\n", cmd);
1206         } else {
1207                 if (t_sec(ent))
1208                         trace_seq_printf(s, "%llu + %u [%s]\n",
1209                                                 t_sector(ent), t_sec(ent), cmd);
1210                 else
1211                         trace_seq_printf(s, "[%s]\n", cmd);
1212         }
1213 }
1214 
1215 static void blk_log_with_error(struct trace_seq *s,
1216                               const struct trace_entry *ent)
1217 {
1218         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1219                 blk_log_dump_pdu(s, ent);
1220                 trace_seq_printf(s, "[%d]\n", t_error(ent));
1221         } else {
1222                 if (t_sec(ent))
1223                         trace_seq_printf(s, "%llu + %u [%d]\n",
1224                                          t_sector(ent),
1225                                          t_sec(ent), t_error(ent));
1226                 else
1227                         trace_seq_printf(s, "%llu [%d]\n",
1228                                          t_sector(ent), t_error(ent));
1229         }
1230 }
1231 
1232 static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1233 {
1234         struct blk_io_trace_remap r = { .device_from = 0, };
1235 
1236         get_pdu_remap(ent, &r);
1237         trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1238                          t_sector(ent), t_sec(ent),
1239                          MAJOR(r.device_from), MINOR(r.device_from),
1240                          (unsigned long long)r.sector_from);
1241 }
1242 
1243 static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1244 {
1245         char cmd[TASK_COMM_LEN];
1246 
1247         trace_find_cmdline(ent->pid, cmd);
1248 
1249         trace_seq_printf(s, "[%s]\n", cmd);
1250 }
1251 
1252 static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1253 {
1254         char cmd[TASK_COMM_LEN];
1255 
1256         trace_find_cmdline(ent->pid, cmd);
1257 
1258         trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1259 }
1260 
1261 static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1262 {
1263         char cmd[TASK_COMM_LEN];
1264 
1265         trace_find_cmdline(ent->pid, cmd);
1266 
1267         trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1268                          get_pdu_int(ent), cmd);
1269 }
1270 
1271 static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1272 {
1273         const struct blk_io_trace *t = te_blk_io_trace(ent);
1274 
1275         trace_seq_putmem(s, t + 1, t->pdu_len);
1276         trace_seq_putc(s, '\n');
1277 }
1278 
1279 /*
1280  * struct tracer operations
1281  */
1282 
1283 static void blk_tracer_print_header(struct seq_file *m)
1284 {
1285         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1286                 return;
1287         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1288                     "#  |     |     |           |   |   |\n");
1289 }
1290 
1291 static void blk_tracer_start(struct trace_array *tr)
1292 {
1293         blk_tracer_enabled = true;
1294 }
1295 
1296 static int blk_tracer_init(struct trace_array *tr)
1297 {
1298         blk_tr = tr;
1299         blk_tracer_start(tr);
1300         return 0;
1301 }
1302 
1303 static void blk_tracer_stop(struct trace_array *tr)
1304 {
1305         blk_tracer_enabled = false;
1306 }
1307 
1308 static void blk_tracer_reset(struct trace_array *tr)
1309 {
1310         blk_tracer_stop(tr);
1311 }
1312 
1313 static const struct {
1314         const char *act[2];
1315         void       (*print)(struct trace_seq *s, const struct trace_entry *ent);
1316 } what2act[] = {
1317         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1318         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1319         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1320         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1321         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1322         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1323         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1324         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1325         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1326         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1327         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1328         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1329         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1330         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1331         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1332 };
1333 
1334 static enum print_line_t print_one_line(struct trace_iterator *iter,
1335                                         bool classic)
1336 {
1337         struct trace_array *tr = iter->tr;
1338         struct trace_seq *s = &iter->seq;
1339         const struct blk_io_trace *t;
1340         u16 what;
1341         bool long_act;
1342         blk_log_action_t *log_action;
1343 
1344         t          = te_blk_io_trace(iter->ent);
1345         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1346         long_act   = !!(tr->trace_flags & TRACE_ITER_VERBOSE);
1347         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1348 
1349         if (t->action == BLK_TN_MESSAGE) {
1350                 log_action(iter, long_act ? "message" : "m");
1351                 blk_log_msg(s, iter->ent);
1352         }
1353 
1354         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1355                 trace_seq_printf(s, "Unknown action %x\n", what);
1356         else {
1357                 log_action(iter, what2act[what].act[long_act]);
1358                 what2act[what].print(s, iter->ent);
1359         }
1360 
1361         return trace_handle_return(s);
1362 }
1363 
1364 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1365                                                int flags, struct trace_event *event)
1366 {
1367         return print_one_line(iter, false);
1368 }
1369 
1370 static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1371 {
1372         struct trace_seq *s = &iter->seq;
1373         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1374         const int offset = offsetof(struct blk_io_trace, sector);
1375         struct blk_io_trace old = {
1376                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1377                 .time     = iter->ts,
1378         };
1379 
1380         trace_seq_putmem(s, &old, offset);
1381         trace_seq_putmem(s, &t->sector,
1382                          sizeof(old) - offset + t->pdu_len);
1383 }
1384 
1385 static enum print_line_t
1386 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1387                              struct trace_event *event)
1388 {
1389         blk_trace_synthesize_old_trace(iter);
1390 
1391         return trace_handle_return(&iter->seq);
1392 }
1393 
1394 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1395 {
1396         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1397                 return TRACE_TYPE_UNHANDLED;
1398 
1399         return print_one_line(iter, true);
1400 }
1401 
1402 static int
1403 blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1404 {
1405         /* don't output context-info for blk_classic output */
1406         if (bit == TRACE_BLK_OPT_CLASSIC) {
1407                 if (set)
1408                         tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1409                 else
1410                         tr->trace_flags |= TRACE_ITER_CONTEXT_INFO;
1411         }
1412         return 0;
1413 }
1414 
1415 static struct tracer blk_tracer __read_mostly = {
1416         .name           = "blk",
1417         .init           = blk_tracer_init,
1418         .reset          = blk_tracer_reset,
1419         .start          = blk_tracer_start,
1420         .stop           = blk_tracer_stop,
1421         .print_header   = blk_tracer_print_header,
1422         .print_line     = blk_tracer_print_line,
1423         .flags          = &blk_tracer_flags,
1424         .set_flag       = blk_tracer_set_flag,
1425 };
1426 
1427 static struct trace_event_functions trace_blk_event_funcs = {
1428         .trace          = blk_trace_event_print,
1429         .binary         = blk_trace_event_print_binary,
1430 };
1431 
1432 static struct trace_event trace_blk_event = {
1433         .type           = TRACE_BLK,
1434         .funcs          = &trace_blk_event_funcs,
1435 };
1436 
1437 static int __init init_blk_tracer(void)
1438 {
1439         if (!register_trace_event(&trace_blk_event)) {
1440                 pr_warn("Warning: could not register block events\n");
1441                 return 1;
1442         }
1443 
1444         if (register_tracer(&blk_tracer) != 0) {
1445                 pr_warn("Warning: could not register the block tracer\n");
1446                 unregister_trace_event(&trace_blk_event);
1447                 return 1;
1448         }
1449 
1450         return 0;
1451 }
1452 
1453 device_initcall(init_blk_tracer);
1454 
1455 static int blk_trace_remove_queue(struct request_queue *q)
1456 {
1457         struct blk_trace *bt;
1458 
1459         bt = xchg(&q->blk_trace, NULL);
1460         if (bt == NULL)
1461                 return -EINVAL;
1462 
1463         if (atomic_dec_and_test(&blk_probes_ref))
1464                 blk_unregister_tracepoints();
1465 
1466         blk_trace_free(bt);
1467         return 0;
1468 }
1469 
1470 /*
1471  * Setup everything required to start tracing
1472  */
1473 static int blk_trace_setup_queue(struct request_queue *q,
1474                                  struct block_device *bdev)
1475 {
1476         struct blk_trace *bt = NULL;
1477         int ret = -ENOMEM;
1478 
1479         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1480         if (!bt)
1481                 return -ENOMEM;
1482 
1483         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1484         if (!bt->msg_data)
1485                 goto free_bt;
1486 
1487         bt->dev = bdev->bd_dev;
1488         bt->act_mask = (u16)-1;
1489 
1490         blk_trace_setup_lba(bt, bdev);
1491 
1492         ret = -EBUSY;
1493         if (cmpxchg(&q->blk_trace, NULL, bt))
1494                 goto free_bt;
1495 
1496         if (atomic_inc_return(&blk_probes_ref) == 1)
1497                 blk_register_tracepoints();
1498         return 0;
1499 
1500 free_bt:
1501         blk_trace_free(bt);
1502         return ret;
1503 }
1504 
1505 /*
1506  * sysfs interface to enable and configure tracing
1507  */
1508 
1509 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1510                                          struct device_attribute *attr,
1511                                          char *buf);
1512 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1513                                           struct device_attribute *attr,
1514                                           const char *buf, size_t count);
1515 #define BLK_TRACE_DEVICE_ATTR(_name) \
1516         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1517                     sysfs_blk_trace_attr_show, \
1518                     sysfs_blk_trace_attr_store)
1519 
1520 static BLK_TRACE_DEVICE_ATTR(enable);
1521 static BLK_TRACE_DEVICE_ATTR(act_mask);
1522 static BLK_TRACE_DEVICE_ATTR(pid);
1523 static BLK_TRACE_DEVICE_ATTR(start_lba);
1524 static BLK_TRACE_DEVICE_ATTR(end_lba);
1525 
1526 static struct attribute *blk_trace_attrs[] = {
1527         &dev_attr_enable.attr,
1528         &dev_attr_act_mask.attr,
1529         &dev_attr_pid.attr,
1530         &dev_attr_start_lba.attr,
1531         &dev_attr_end_lba.attr,
1532         NULL
1533 };
1534 
1535 struct attribute_group blk_trace_attr_group = {
1536         .name  = "trace",
1537         .attrs = blk_trace_attrs,
1538 };
1539 
1540 static const struct {
1541         int mask;
1542         const char *str;
1543 } mask_maps[] = {
1544         { BLK_TC_READ,          "read"          },
1545         { BLK_TC_WRITE,         "write"         },
1546         { BLK_TC_FLUSH,         "flush"         },
1547         { BLK_TC_SYNC,          "sync"          },
1548         { BLK_TC_QUEUE,         "queue"         },
1549         { BLK_TC_REQUEUE,       "requeue"       },
1550         { BLK_TC_ISSUE,         "issue"         },
1551         { BLK_TC_COMPLETE,      "complete"      },
1552         { BLK_TC_FS,            "fs"            },
1553         { BLK_TC_PC,            "pc"            },
1554         { BLK_TC_AHEAD,         "ahead"         },
1555         { BLK_TC_META,          "meta"          },
1556         { BLK_TC_DISCARD,       "discard"       },
1557         { BLK_TC_DRV_DATA,      "drv_data"      },
1558         { BLK_TC_FUA,           "fua"           },
1559 };
1560 
1561 static int blk_trace_str2mask(const char *str)
1562 {
1563         int i;
1564         int mask = 0;
1565         char *buf, *s, *token;
1566 
1567         buf = kstrdup(str, GFP_KERNEL);
1568         if (buf == NULL)
1569                 return -ENOMEM;
1570         s = strstrip(buf);
1571 
1572         while (1) {
1573                 token = strsep(&s, ",");
1574                 if (token == NULL)
1575                         break;
1576 
1577                 if (*token == '\0')
1578                         continue;
1579 
1580                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1581                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1582                                 mask |= mask_maps[i].mask;
1583                                 break;
1584                         }
1585                 }
1586                 if (i == ARRAY_SIZE(mask_maps)) {
1587                         mask = -EINVAL;
1588                         break;
1589                 }
1590         }
1591         kfree(buf);
1592 
1593         return mask;
1594 }
1595 
1596 static ssize_t blk_trace_mask2str(char *buf, int mask)
1597 {
1598         int i;
1599         char *p = buf;
1600 
1601         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1602                 if (mask & mask_maps[i].mask) {
1603                         p += sprintf(p, "%s%s",
1604                                     (p == buf) ? "" : ",", mask_maps[i].str);
1605                 }
1606         }
1607         *p++ = '\n';
1608 
1609         return p - buf;
1610 }
1611 
1612 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1613 {
1614         if (bdev->bd_disk == NULL)
1615                 return NULL;
1616 
1617         return bdev_get_queue(bdev);
1618 }
1619 
1620 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1621                                          struct device_attribute *attr,
1622                                          char *buf)
1623 {
1624         struct hd_struct *p = dev_to_part(dev);
1625         struct request_queue *q;
1626         struct block_device *bdev;
1627         ssize_t ret = -ENXIO;
1628 
1629         bdev = bdget(part_devt(p));
1630         if (bdev == NULL)
1631                 goto out;
1632 
1633         q = blk_trace_get_queue(bdev);
1634         if (q == NULL)
1635                 goto out_bdput;
1636 
1637         mutex_lock(&bdev->bd_mutex);
1638 
1639         if (attr == &dev_attr_enable) {
1640                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1641                 goto out_unlock_bdev;
1642         }
1643 
1644         if (q->blk_trace == NULL)
1645                 ret = sprintf(buf, "disabled\n");
1646         else if (attr == &dev_attr_act_mask)
1647                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1648         else if (attr == &dev_attr_pid)
1649                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1650         else if (attr == &dev_attr_start_lba)
1651                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1652         else if (attr == &dev_attr_end_lba)
1653                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1654 
1655 out_unlock_bdev:
1656         mutex_unlock(&bdev->bd_mutex);
1657 out_bdput:
1658         bdput(bdev);
1659 out:
1660         return ret;
1661 }
1662 
1663 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1664                                           struct device_attribute *attr,
1665                                           const char *buf, size_t count)
1666 {
1667         struct block_device *bdev;
1668         struct request_queue *q;
1669         struct hd_struct *p;
1670         u64 value;
1671         ssize_t ret = -EINVAL;
1672 
1673         if (count == 0)
1674                 goto out;
1675 
1676         if (attr == &dev_attr_act_mask) {
1677                 if (sscanf(buf, "%llx", &value) != 1) {
1678                         /* Assume it is a list of trace category names */
1679                         ret = blk_trace_str2mask(buf);
1680                         if (ret < 0)
1681                                 goto out;
1682                         value = ret;
1683                 }
1684         } else if (sscanf(buf, "%llu", &value) != 1)
1685                 goto out;
1686 
1687         ret = -ENXIO;
1688 
1689         p = dev_to_part(dev);
1690         bdev = bdget(part_devt(p));
1691         if (bdev == NULL)
1692                 goto out;
1693 
1694         q = blk_trace_get_queue(bdev);
1695         if (q == NULL)
1696                 goto out_bdput;
1697 
1698         mutex_lock(&bdev->bd_mutex);
1699 
1700         if (attr == &dev_attr_enable) {
1701                 if (value)
1702                         ret = blk_trace_setup_queue(q, bdev);
1703                 else
1704                         ret = blk_trace_remove_queue(q);
1705                 goto out_unlock_bdev;
1706         }
1707 
1708         ret = 0;
1709         if (q->blk_trace == NULL)
1710                 ret = blk_trace_setup_queue(q, bdev);
1711 
1712         if (ret == 0) {
1713                 if (attr == &dev_attr_act_mask)
1714                         q->blk_trace->act_mask = value;
1715                 else if (attr == &dev_attr_pid)
1716                         q->blk_trace->pid = value;
1717                 else if (attr == &dev_attr_start_lba)
1718                         q->blk_trace->start_lba = value;
1719                 else if (attr == &dev_attr_end_lba)
1720                         q->blk_trace->end_lba = value;
1721         }
1722 
1723 out_unlock_bdev:
1724         mutex_unlock(&bdev->bd_mutex);
1725 out_bdput:
1726         bdput(bdev);
1727 out:
1728         return ret ? ret : count;
1729 }
1730 
1731 int blk_trace_init_sysfs(struct device *dev)
1732 {
1733         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1734 }
1735 
1736 void blk_trace_remove_sysfs(struct device *dev)
1737 {
1738         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1739 }
1740 
1741 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1742 
1743 #ifdef CONFIG_EVENT_TRACING
1744 
1745 void blk_dump_cmd(char *buf, struct request *rq)
1746 {
1747         int i, end;
1748         int len = rq->cmd_len;
1749         unsigned char *cmd = rq->cmd;
1750 
1751         if (rq->cmd_type != REQ_TYPE_BLOCK_PC) {
1752                 buf[0] = '\0';
1753                 return;
1754         }
1755 
1756         for (end = len - 1; end >= 0; end--)
1757                 if (cmd[end])
1758                         break;
1759         end++;
1760 
1761         for (i = 0; i < len; i++) {
1762                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1763                 if (i == end && end != len - 1) {
1764                         sprintf(buf, " ..");
1765                         break;
1766                 }
1767         }
1768 }
1769 
1770 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1771 {
1772         int i = 0;
1773 
1774         if (rw & REQ_FLUSH)
1775                 rwbs[i++] = 'F';
1776 
1777         if (rw & WRITE)
1778                 rwbs[i++] = 'W';
1779         else if (rw & REQ_DISCARD)
1780                 rwbs[i++] = 'D';
1781         else if (bytes)
1782                 rwbs[i++] = 'R';
1783         else
1784                 rwbs[i++] = 'N';
1785 
1786         if (rw & REQ_FUA)
1787                 rwbs[i++] = 'F';
1788         if (rw & REQ_RAHEAD)
1789                 rwbs[i++] = 'A';
1790         if (rw & REQ_SYNC)
1791                 rwbs[i++] = 'S';
1792         if (rw & REQ_META)
1793                 rwbs[i++] = 'M';
1794         if (rw & REQ_SECURE)
1795                 rwbs[i++] = 'E';
1796 
1797         rwbs[i] = '\0';
1798 }
1799 EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1800 
1801 #endif /* CONFIG_EVENT_TRACING */
1802 
1803 

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