simple_open: automatically convert to simple_open()
[linux-3.10.git] / kernel / trace / blktrace.c
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
30 #include <trace/events/block.h>
31
32 #include "trace_output.h"
33
34 #ifdef CONFIG_BLK_DEV_IO_TRACE
35
36 static unsigned int blktrace_seq __read_mostly = 1;
37
38 static struct trace_array *blk_tr;
39 static bool blk_tracer_enabled __read_mostly;
40
41 /* Select an alternative, minimalistic output than the original one */
42 #define TRACE_BLK_OPT_CLASSIC   0x1
43
44 static struct tracer_opt blk_tracer_opts[] = {
45         /* Default disable the minimalistic output */
46         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
47         { }
48 };
49
50 static struct tracer_flags blk_tracer_flags = {
51         .val  = 0,
52         .opts = blk_tracer_opts,
53 };
54
55 /* Global reference count of probes */
56 static atomic_t blk_probes_ref = ATOMIC_INIT(0);
57
58 static void blk_register_tracepoints(void);
59 static void blk_unregister_tracepoints(void);
60
61 /*
62  * Send out a notify message.
63  */
64 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
65                        const void *data, size_t len)
66 {
67         struct blk_io_trace *t;
68         struct ring_buffer_event *event = NULL;
69         struct ring_buffer *buffer = NULL;
70         int pc = 0;
71         int cpu = smp_processor_id();
72         bool blk_tracer = blk_tracer_enabled;
73
74         if (blk_tracer) {
75                 buffer = blk_tr->buffer;
76                 pc = preempt_count();
77                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
78                                                   sizeof(*t) + len,
79                                                   0, pc);
80                 if (!event)
81                         return;
82                 t = ring_buffer_event_data(event);
83                 goto record_it;
84         }
85
86         if (!bt->rchan)
87                 return;
88
89         t = relay_reserve(bt->rchan, sizeof(*t) + len);
90         if (t) {
91                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
92                 t->time = ktime_to_ns(ktime_get());
93 record_it:
94                 t->device = bt->dev;
95                 t->action = action;
96                 t->pid = pid;
97                 t->cpu = cpu;
98                 t->pdu_len = len;
99                 memcpy((void *) t + sizeof(*t), data, len);
100
101                 if (blk_tracer)
102                         trace_buffer_unlock_commit(buffer, event, 0, pc);
103         }
104 }
105
106 /*
107  * Send out a notify for this process, if we haven't done so since a trace
108  * started
109  */
110 static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
111 {
112         tsk->btrace_seq = blktrace_seq;
113         trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));
114 }
115
116 static void trace_note_time(struct blk_trace *bt)
117 {
118         struct timespec now;
119         unsigned long flags;
120         u32 words[2];
121
122         getnstimeofday(&now);
123         words[0] = now.tv_sec;
124         words[1] = now.tv_nsec;
125
126         local_irq_save(flags);
127         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
128         local_irq_restore(flags);
129 }
130
131 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
132 {
133         int n;
134         va_list args;
135         unsigned long flags;
136         char *buf;
137
138         if (unlikely(bt->trace_state != Blktrace_running &&
139                      !blk_tracer_enabled))
140                 return;
141
142         /*
143          * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
144          * message to the trace.
145          */
146         if (!(bt->act_mask & BLK_TC_NOTIFY))
147                 return;
148
149         local_irq_save(flags);
150         buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
151         va_start(args, fmt);
152         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
153         va_end(args);
154
155         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
156         local_irq_restore(flags);
157 }
158 EXPORT_SYMBOL_GPL(__trace_note_message);
159
160 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
161                          pid_t pid)
162 {
163         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
164                 return 1;
165         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
166                 return 1;
167         if (bt->pid && pid != bt->pid)
168                 return 1;
169
170         return 0;
171 }
172
173 /*
174  * Data direction bit lookup
175  */
176 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
177                                  BLK_TC_ACT(BLK_TC_WRITE) };
178
179 #define BLK_TC_RAHEAD           BLK_TC_AHEAD
180
181 /* The ilog2() calls fall out because they're constant */
182 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
183           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
184
185 /*
186  * The worker for the various blk_add_trace*() types. Fills out a
187  * blk_io_trace structure and places it in a per-cpu subbuffer.
188  */
189 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
190                      int rw, u32 what, int error, int pdu_len, void *pdu_data)
191 {
192         struct task_struct *tsk = current;
193         struct ring_buffer_event *event = NULL;
194         struct ring_buffer *buffer = NULL;
195         struct blk_io_trace *t;
196         unsigned long flags = 0;
197         unsigned long *sequence;
198         pid_t pid;
199         int cpu, pc = 0;
200         bool blk_tracer = blk_tracer_enabled;
201
202         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
203                 return;
204
205         what |= ddir_act[rw & WRITE];
206         what |= MASK_TC_BIT(rw, SYNC);
207         what |= MASK_TC_BIT(rw, RAHEAD);
208         what |= MASK_TC_BIT(rw, META);
209         what |= MASK_TC_BIT(rw, DISCARD);
210         what |= MASK_TC_BIT(rw, FLUSH);
211         what |= MASK_TC_BIT(rw, FUA);
212
213         pid = tsk->pid;
214         if (act_log_check(bt, what, sector, pid))
215                 return;
216         cpu = raw_smp_processor_id();
217
218         if (blk_tracer) {
219                 tracing_record_cmdline(current);
220
221                 buffer = blk_tr->buffer;
222                 pc = preempt_count();
223                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
224                                                   sizeof(*t) + pdu_len,
225                                                   0, pc);
226                 if (!event)
227                         return;
228                 t = ring_buffer_event_data(event);
229                 goto record_it;
230         }
231
232         /*
233          * A word about the locking here - we disable interrupts to reserve
234          * some space in the relay per-cpu buffer, to prevent an irq
235          * from coming in and stepping on our toes.
236          */
237         local_irq_save(flags);
238
239         if (unlikely(tsk->btrace_seq != blktrace_seq))
240                 trace_note_tsk(bt, tsk);
241
242         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
243         if (t) {
244                 sequence = per_cpu_ptr(bt->sequence, cpu);
245
246                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
247                 t->sequence = ++(*sequence);
248                 t->time = ktime_to_ns(ktime_get());
249 record_it:
250                 /*
251                  * These two are not needed in ftrace as they are in the
252                  * generic trace_entry, filled by tracing_generic_entry_update,
253                  * but for the trace_event->bin() synthesizer benefit we do it
254                  * here too.
255                  */
256                 t->cpu = cpu;
257                 t->pid = pid;
258
259                 t->sector = sector;
260                 t->bytes = bytes;
261                 t->action = what;
262                 t->device = bt->dev;
263                 t->error = error;
264                 t->pdu_len = pdu_len;
265
266                 if (pdu_len)
267                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
268
269                 if (blk_tracer) {
270                         trace_buffer_unlock_commit(buffer, event, 0, pc);
271                         return;
272                 }
273         }
274
275         local_irq_restore(flags);
276 }
277
278 static struct dentry *blk_tree_root;
279 static DEFINE_MUTEX(blk_tree_mutex);
280
281 static void blk_trace_free(struct blk_trace *bt)
282 {
283         debugfs_remove(bt->msg_file);
284         debugfs_remove(bt->dropped_file);
285         relay_close(bt->rchan);
286         debugfs_remove(bt->dir);
287         free_percpu(bt->sequence);
288         free_percpu(bt->msg_data);
289         kfree(bt);
290 }
291
292 static void blk_trace_cleanup(struct blk_trace *bt)
293 {
294         blk_trace_free(bt);
295         if (atomic_dec_and_test(&blk_probes_ref))
296                 blk_unregister_tracepoints();
297 }
298
299 int blk_trace_remove(struct request_queue *q)
300 {
301         struct blk_trace *bt;
302
303         bt = xchg(&q->blk_trace, NULL);
304         if (!bt)
305                 return -EINVAL;
306
307         if (bt->trace_state != Blktrace_running)
308                 blk_trace_cleanup(bt);
309
310         return 0;
311 }
312 EXPORT_SYMBOL_GPL(blk_trace_remove);
313
314 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
315                                 size_t count, loff_t *ppos)
316 {
317         struct blk_trace *bt = filp->private_data;
318         char buf[16];
319
320         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
321
322         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
323 }
324
325 static const struct file_operations blk_dropped_fops = {
326         .owner =        THIS_MODULE,
327         .open =         simple_open,
328         .read =         blk_dropped_read,
329         .llseek =       default_llseek,
330 };
331
332 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
333                                 size_t count, loff_t *ppos)
334 {
335         char *msg;
336         struct blk_trace *bt;
337
338         if (count >= BLK_TN_MAX_MSG)
339                 return -EINVAL;
340
341         msg = kmalloc(count + 1, GFP_KERNEL);
342         if (msg == NULL)
343                 return -ENOMEM;
344
345         if (copy_from_user(msg, buffer, count)) {
346                 kfree(msg);
347                 return -EFAULT;
348         }
349
350         msg[count] = '\0';
351         bt = filp->private_data;
352         __trace_note_message(bt, "%s", msg);
353         kfree(msg);
354
355         return count;
356 }
357
358 static const struct file_operations blk_msg_fops = {
359         .owner =        THIS_MODULE,
360         .open =         simple_open,
361         .write =        blk_msg_write,
362         .llseek =       noop_llseek,
363 };
364
365 /*
366  * Keep track of how many times we encountered a full subbuffer, to aid
367  * the user space app in telling how many lost events there were.
368  */
369 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
370                                      void *prev_subbuf, size_t prev_padding)
371 {
372         struct blk_trace *bt;
373
374         if (!relay_buf_full(buf))
375                 return 1;
376
377         bt = buf->chan->private_data;
378         atomic_inc(&bt->dropped);
379         return 0;
380 }
381
382 static int blk_remove_buf_file_callback(struct dentry *dentry)
383 {
384         debugfs_remove(dentry);
385
386         return 0;
387 }
388
389 static struct dentry *blk_create_buf_file_callback(const char *filename,
390                                                    struct dentry *parent,
391                                                    umode_t mode,
392                                                    struct rchan_buf *buf,
393                                                    int *is_global)
394 {
395         return debugfs_create_file(filename, mode, parent, buf,
396                                         &relay_file_operations);
397 }
398
399 static struct rchan_callbacks blk_relay_callbacks = {
400         .subbuf_start           = blk_subbuf_start_callback,
401         .create_buf_file        = blk_create_buf_file_callback,
402         .remove_buf_file        = blk_remove_buf_file_callback,
403 };
404
405 static void blk_trace_setup_lba(struct blk_trace *bt,
406                                 struct block_device *bdev)
407 {
408         struct hd_struct *part = NULL;
409
410         if (bdev)
411                 part = bdev->bd_part;
412
413         if (part) {
414                 bt->start_lba = part->start_sect;
415                 bt->end_lba = part->start_sect + part->nr_sects;
416         } else {
417                 bt->start_lba = 0;
418                 bt->end_lba = -1ULL;
419         }
420 }
421
422 /*
423  * Setup everything required to start tracing
424  */
425 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
426                        struct block_device *bdev,
427                        struct blk_user_trace_setup *buts)
428 {
429         struct blk_trace *old_bt, *bt = NULL;
430         struct dentry *dir = NULL;
431         int ret, i;
432
433         if (!buts->buf_size || !buts->buf_nr)
434                 return -EINVAL;
435
436         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
437         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
438
439         /*
440          * some device names have larger paths - convert the slashes
441          * to underscores for this to work as expected
442          */
443         for (i = 0; i < strlen(buts->name); i++)
444                 if (buts->name[i] == '/')
445                         buts->name[i] = '_';
446
447         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
448         if (!bt)
449                 return -ENOMEM;
450
451         ret = -ENOMEM;
452         bt->sequence = alloc_percpu(unsigned long);
453         if (!bt->sequence)
454                 goto err;
455
456         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
457         if (!bt->msg_data)
458                 goto err;
459
460         ret = -ENOENT;
461
462         mutex_lock(&blk_tree_mutex);
463         if (!blk_tree_root) {
464                 blk_tree_root = debugfs_create_dir("block", NULL);
465                 if (!blk_tree_root) {
466                         mutex_unlock(&blk_tree_mutex);
467                         goto err;
468                 }
469         }
470         mutex_unlock(&blk_tree_mutex);
471
472         dir = debugfs_create_dir(buts->name, blk_tree_root);
473
474         if (!dir)
475                 goto err;
476
477         bt->dir = dir;
478         bt->dev = dev;
479         atomic_set(&bt->dropped, 0);
480
481         ret = -EIO;
482         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
483                                                &blk_dropped_fops);
484         if (!bt->dropped_file)
485                 goto err;
486
487         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
488         if (!bt->msg_file)
489                 goto err;
490
491         bt->rchan = relay_open("trace", dir, buts->buf_size,
492                                 buts->buf_nr, &blk_relay_callbacks, bt);
493         if (!bt->rchan)
494                 goto err;
495
496         bt->act_mask = buts->act_mask;
497         if (!bt->act_mask)
498                 bt->act_mask = (u16) -1;
499
500         blk_trace_setup_lba(bt, bdev);
501
502         /* overwrite with user settings */
503         if (buts->start_lba)
504                 bt->start_lba = buts->start_lba;
505         if (buts->end_lba)
506                 bt->end_lba = buts->end_lba;
507
508         bt->pid = buts->pid;
509         bt->trace_state = Blktrace_setup;
510
511         ret = -EBUSY;
512         old_bt = xchg(&q->blk_trace, bt);
513         if (old_bt) {
514                 (void) xchg(&q->blk_trace, old_bt);
515                 goto err;
516         }
517
518         if (atomic_inc_return(&blk_probes_ref) == 1)
519                 blk_register_tracepoints();
520
521         return 0;
522 err:
523         blk_trace_free(bt);
524         return ret;
525 }
526
527 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
528                     struct block_device *bdev,
529                     char __user *arg)
530 {
531         struct blk_user_trace_setup buts;
532         int ret;
533
534         ret = copy_from_user(&buts, arg, sizeof(buts));
535         if (ret)
536                 return -EFAULT;
537
538         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
539         if (ret)
540                 return ret;
541
542         if (copy_to_user(arg, &buts, sizeof(buts))) {
543                 blk_trace_remove(q);
544                 return -EFAULT;
545         }
546         return 0;
547 }
548 EXPORT_SYMBOL_GPL(blk_trace_setup);
549
550 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
551 static int compat_blk_trace_setup(struct request_queue *q, char *name,
552                                   dev_t dev, struct block_device *bdev,
553                                   char __user *arg)
554 {
555         struct blk_user_trace_setup buts;
556         struct compat_blk_user_trace_setup cbuts;
557         int ret;
558
559         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
560                 return -EFAULT;
561
562         buts = (struct blk_user_trace_setup) {
563                 .act_mask = cbuts.act_mask,
564                 .buf_size = cbuts.buf_size,
565                 .buf_nr = cbuts.buf_nr,
566                 .start_lba = cbuts.start_lba,
567                 .end_lba = cbuts.end_lba,
568                 .pid = cbuts.pid,
569         };
570         memcpy(&buts.name, &cbuts.name, 32);
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, 32)) {
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
605                         trace_note_time(bt);
606                         ret = 0;
607                 }
608         } else {
609                 if (bt->trace_state == Blktrace_running) {
610                         bt->trace_state = Blktrace_stopped;
611                         relay_flush(bt->rchan);
612                         ret = 0;
613                 }
614         }
615
616         return ret;
617 }
618 EXPORT_SYMBOL_GPL(blk_trace_startstop);
619
620 /**
621  * blk_trace_ioctl: - handle the ioctls associated with tracing
622  * @bdev:       the block device
623  * @cmd:        the ioctl cmd
624  * @arg:        the argument data, if any
625  *
626  **/
627 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
628 {
629         struct request_queue *q;
630         int ret, start = 0;
631         char b[BDEVNAME_SIZE];
632
633         q = bdev_get_queue(bdev);
634         if (!q)
635                 return -ENXIO;
636
637         mutex_lock(&bdev->bd_mutex);
638
639         switch (cmd) {
640         case BLKTRACESETUP:
641                 bdevname(bdev, b);
642                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
643                 break;
644 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
645         case BLKTRACESETUP32:
646                 bdevname(bdev, b);
647                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
648                 break;
649 #endif
650         case BLKTRACESTART:
651                 start = 1;
652         case BLKTRACESTOP:
653                 ret = blk_trace_startstop(q, start);
654                 break;
655         case BLKTRACETEARDOWN:
656                 ret = blk_trace_remove(q);
657                 break;
658         default:
659                 ret = -ENOTTY;
660                 break;
661         }
662
663         mutex_unlock(&bdev->bd_mutex);
664         return ret;
665 }
666
667 /**
668  * blk_trace_shutdown: - stop and cleanup trace structures
669  * @q:    the request queue associated with the device
670  *
671  **/
672 void blk_trace_shutdown(struct request_queue *q)
673 {
674         if (q->blk_trace) {
675                 blk_trace_startstop(q, 0);
676                 blk_trace_remove(q);
677         }
678 }
679
680 /*
681  * blktrace probes
682  */
683
684 /**
685  * blk_add_trace_rq - Add a trace for a request oriented action
686  * @q:          queue the io is for
687  * @rq:         the source request
688  * @what:       the action
689  *
690  * Description:
691  *     Records an action against a request. Will log the bio offset + size.
692  *
693  **/
694 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
695                              u32 what)
696 {
697         struct blk_trace *bt = q->blk_trace;
698
699         if (likely(!bt))
700                 return;
701
702         if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
703                 what |= BLK_TC_ACT(BLK_TC_PC);
704                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), rq->cmd_flags,
705                                 what, rq->errors, rq->cmd_len, rq->cmd);
706         } else  {
707                 what |= BLK_TC_ACT(BLK_TC_FS);
708                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
709                                 rq->cmd_flags, what, rq->errors, 0, NULL);
710         }
711 }
712
713 static void blk_add_trace_rq_abort(void *ignore,
714                                    struct request_queue *q, struct request *rq)
715 {
716         blk_add_trace_rq(q, rq, BLK_TA_ABORT);
717 }
718
719 static void blk_add_trace_rq_insert(void *ignore,
720                                     struct request_queue *q, struct request *rq)
721 {
722         blk_add_trace_rq(q, rq, BLK_TA_INSERT);
723 }
724
725 static void blk_add_trace_rq_issue(void *ignore,
726                                    struct request_queue *q, struct request *rq)
727 {
728         blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
729 }
730
731 static void blk_add_trace_rq_requeue(void *ignore,
732                                      struct request_queue *q,
733                                      struct request *rq)
734 {
735         blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
736 }
737
738 static void blk_add_trace_rq_complete(void *ignore,
739                                       struct request_queue *q,
740                                       struct request *rq)
741 {
742         blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
743 }
744
745 /**
746  * blk_add_trace_bio - Add a trace for a bio oriented action
747  * @q:          queue the io is for
748  * @bio:        the source bio
749  * @what:       the action
750  * @error:      error, if any
751  *
752  * Description:
753  *     Records an action against a bio. Will log the bio offset + size.
754  *
755  **/
756 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
757                               u32 what, int error)
758 {
759         struct blk_trace *bt = q->blk_trace;
760
761         if (likely(!bt))
762                 return;
763
764         if (!error && !bio_flagged(bio, BIO_UPTODATE))
765                 error = EIO;
766
767         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
768                         error, 0, NULL);
769 }
770
771 static void blk_add_trace_bio_bounce(void *ignore,
772                                      struct request_queue *q, struct bio *bio)
773 {
774         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
775 }
776
777 static void blk_add_trace_bio_complete(void *ignore,
778                                        struct request_queue *q, struct bio *bio,
779                                        int error)
780 {
781         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
782 }
783
784 static void blk_add_trace_bio_backmerge(void *ignore,
785                                         struct request_queue *q,
786                                         struct bio *bio)
787 {
788         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
789 }
790
791 static void blk_add_trace_bio_frontmerge(void *ignore,
792                                          struct request_queue *q,
793                                          struct bio *bio)
794 {
795         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
796 }
797
798 static void blk_add_trace_bio_queue(void *ignore,
799                                     struct request_queue *q, struct bio *bio)
800 {
801         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
802 }
803
804 static void blk_add_trace_getrq(void *ignore,
805                                 struct request_queue *q,
806                                 struct bio *bio, int rw)
807 {
808         if (bio)
809                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
810         else {
811                 struct blk_trace *bt = q->blk_trace;
812
813                 if (bt)
814                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
815         }
816 }
817
818
819 static void blk_add_trace_sleeprq(void *ignore,
820                                   struct request_queue *q,
821                                   struct bio *bio, int rw)
822 {
823         if (bio)
824                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
825         else {
826                 struct blk_trace *bt = q->blk_trace;
827
828                 if (bt)
829                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
830                                         0, 0, NULL);
831         }
832 }
833
834 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
835 {
836         struct blk_trace *bt = q->blk_trace;
837
838         if (bt)
839                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
840 }
841
842 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
843                                     unsigned int depth, bool explicit)
844 {
845         struct blk_trace *bt = q->blk_trace;
846
847         if (bt) {
848                 __be64 rpdu = cpu_to_be64(depth);
849                 u32 what;
850
851                 if (explicit)
852                         what = BLK_TA_UNPLUG_IO;
853                 else
854                         what = BLK_TA_UNPLUG_TIMER;
855
856                 __blk_add_trace(bt, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu);
857         }
858 }
859
860 static void blk_add_trace_split(void *ignore,
861                                 struct request_queue *q, struct bio *bio,
862                                 unsigned int pdu)
863 {
864         struct blk_trace *bt = q->blk_trace;
865
866         if (bt) {
867                 __be64 rpdu = cpu_to_be64(pdu);
868
869                 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
870                                 BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
871                                 sizeof(rpdu), &rpdu);
872         }
873 }
874
875 /**
876  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
877  * @ignore:     trace callback data parameter (not used)
878  * @q:          queue the io is for
879  * @bio:        the source bio
880  * @dev:        target device
881  * @from:       source sector
882  *
883  * Description:
884  *     Device mapper or raid target sometimes need to split a bio because
885  *     it spans a stripe (or similar). Add a trace for that action.
886  *
887  **/
888 static void blk_add_trace_bio_remap(void *ignore,
889                                     struct request_queue *q, struct bio *bio,
890                                     dev_t dev, sector_t from)
891 {
892         struct blk_trace *bt = q->blk_trace;
893         struct blk_io_trace_remap r;
894
895         if (likely(!bt))
896                 return;
897
898         r.device_from = cpu_to_be32(dev);
899         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
900         r.sector_from = cpu_to_be64(from);
901
902         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
903                         BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE),
904                         sizeof(r), &r);
905 }
906
907 /**
908  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
909  * @ignore:     trace callback data parameter (not used)
910  * @q:          queue the io is for
911  * @rq:         the source request
912  * @dev:        target device
913  * @from:       source sector
914  *
915  * Description:
916  *     Device mapper remaps request to other devices.
917  *     Add a trace for that action.
918  *
919  **/
920 static void blk_add_trace_rq_remap(void *ignore,
921                                    struct request_queue *q,
922                                    struct request *rq, dev_t dev,
923                                    sector_t from)
924 {
925         struct blk_trace *bt = q->blk_trace;
926         struct blk_io_trace_remap r;
927
928         if (likely(!bt))
929                 return;
930
931         r.device_from = cpu_to_be32(dev);
932         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
933         r.sector_from = cpu_to_be64(from);
934
935         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
936                         rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
937                         sizeof(r), &r);
938 }
939
940 /**
941  * blk_add_driver_data - Add binary message with driver-specific data
942  * @q:          queue the io is for
943  * @rq:         io request
944  * @data:       driver-specific data
945  * @len:        length of driver-specific data
946  *
947  * Description:
948  *     Some drivers might want to write driver-specific data per request.
949  *
950  **/
951 void blk_add_driver_data(struct request_queue *q,
952                          struct request *rq,
953                          void *data, size_t len)
954 {
955         struct blk_trace *bt = q->blk_trace;
956
957         if (likely(!bt))
958                 return;
959
960         if (rq->cmd_type == REQ_TYPE_BLOCK_PC)
961                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
962                                 BLK_TA_DRV_DATA, rq->errors, len, data);
963         else
964                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
965                                 BLK_TA_DRV_DATA, rq->errors, len, data);
966 }
967 EXPORT_SYMBOL_GPL(blk_add_driver_data);
968
969 static void blk_register_tracepoints(void)
970 {
971         int ret;
972
973         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
974         WARN_ON(ret);
975         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
976         WARN_ON(ret);
977         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
978         WARN_ON(ret);
979         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
980         WARN_ON(ret);
981         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
982         WARN_ON(ret);
983         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
984         WARN_ON(ret);
985         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
986         WARN_ON(ret);
987         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
988         WARN_ON(ret);
989         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
990         WARN_ON(ret);
991         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
992         WARN_ON(ret);
993         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
994         WARN_ON(ret);
995         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
996         WARN_ON(ret);
997         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
998         WARN_ON(ret);
999         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1000         WARN_ON(ret);
1001         ret = register_trace_block_split(blk_add_trace_split, NULL);
1002         WARN_ON(ret);
1003         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1004         WARN_ON(ret);
1005         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1006         WARN_ON(ret);
1007 }
1008
1009 static void blk_unregister_tracepoints(void)
1010 {
1011         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1012         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1013         unregister_trace_block_split(blk_add_trace_split, NULL);
1014         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1015         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1016         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1017         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1018         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1019         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1020         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1021         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1022         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1023         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1024         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1025         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1026         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1027         unregister_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
1028
1029         tracepoint_synchronize_unregister();
1030 }
1031
1032 /*
1033  * struct blk_io_tracer formatting routines
1034  */
1035
1036 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1037 {
1038         int i = 0;
1039         int tc = t->action >> BLK_TC_SHIFT;
1040
1041         if (t->action == BLK_TN_MESSAGE) {
1042                 rwbs[i++] = 'N';
1043                 goto out;
1044         }
1045
1046         if (tc & BLK_TC_FLUSH)
1047                 rwbs[i++] = 'F';
1048
1049         if (tc & BLK_TC_DISCARD)
1050                 rwbs[i++] = 'D';
1051         else if (tc & BLK_TC_WRITE)
1052                 rwbs[i++] = 'W';
1053         else if (t->bytes)
1054                 rwbs[i++] = 'R';
1055         else
1056                 rwbs[i++] = 'N';
1057
1058         if (tc & BLK_TC_FUA)
1059                 rwbs[i++] = 'F';
1060         if (tc & BLK_TC_AHEAD)
1061                 rwbs[i++] = 'A';
1062         if (tc & BLK_TC_SYNC)
1063                 rwbs[i++] = 'S';
1064         if (tc & BLK_TC_META)
1065                 rwbs[i++] = 'M';
1066 out:
1067         rwbs[i] = '\0';
1068 }
1069
1070 static inline
1071 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1072 {
1073         return (const struct blk_io_trace *)ent;
1074 }
1075
1076 static inline const void *pdu_start(const struct trace_entry *ent)
1077 {
1078         return te_blk_io_trace(ent) + 1;
1079 }
1080
1081 static inline u32 t_action(const struct trace_entry *ent)
1082 {
1083         return te_blk_io_trace(ent)->action;
1084 }
1085
1086 static inline u32 t_bytes(const struct trace_entry *ent)
1087 {
1088         return te_blk_io_trace(ent)->bytes;
1089 }
1090
1091 static inline u32 t_sec(const struct trace_entry *ent)
1092 {
1093         return te_blk_io_trace(ent)->bytes >> 9;
1094 }
1095
1096 static inline unsigned long long t_sector(const struct trace_entry *ent)
1097 {
1098         return te_blk_io_trace(ent)->sector;
1099 }
1100
1101 static inline __u16 t_error(const struct trace_entry *ent)
1102 {
1103         return te_blk_io_trace(ent)->error;
1104 }
1105
1106 static __u64 get_pdu_int(const struct trace_entry *ent)
1107 {
1108         const __u64 *val = pdu_start(ent);
1109         return be64_to_cpu(*val);
1110 }
1111
1112 static void get_pdu_remap(const struct trace_entry *ent,
1113                           struct blk_io_trace_remap *r)
1114 {
1115         const struct blk_io_trace_remap *__r = pdu_start(ent);
1116         __u64 sector_from = __r->sector_from;
1117
1118         r->device_from = be32_to_cpu(__r->device_from);
1119         r->device_to   = be32_to_cpu(__r->device_to);
1120         r->sector_from = be64_to_cpu(sector_from);
1121 }
1122
1123 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1124
1125 static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1126 {
1127         char rwbs[RWBS_LEN];
1128         unsigned long long ts  = iter->ts;
1129         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1130         unsigned secs          = (unsigned long)ts;
1131         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1132
1133         fill_rwbs(rwbs, t);
1134
1135         return trace_seq_printf(&iter->seq,
1136                                 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1137                                 MAJOR(t->device), MINOR(t->device), iter->cpu,
1138                                 secs, nsec_rem, iter->ent->pid, act, rwbs);
1139 }
1140
1141 static int blk_log_action(struct trace_iterator *iter, const char *act)
1142 {
1143         char rwbs[RWBS_LEN];
1144         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1145
1146         fill_rwbs(rwbs, t);
1147         return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1148                                 MAJOR(t->device), MINOR(t->device), act, rwbs);
1149 }
1150
1151 static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1152 {
1153         const unsigned char *pdu_buf;
1154         int pdu_len;
1155         int i, end, ret;
1156
1157         pdu_buf = pdu_start(ent);
1158         pdu_len = te_blk_io_trace(ent)->pdu_len;
1159
1160         if (!pdu_len)
1161                 return 1;
1162
1163         /* find the last zero that needs to be printed */
1164         for (end = pdu_len - 1; end >= 0; end--)
1165                 if (pdu_buf[end])
1166                         break;
1167         end++;
1168
1169         if (!trace_seq_putc(s, '('))
1170                 return 0;
1171
1172         for (i = 0; i < pdu_len; i++) {
1173
1174                 ret = trace_seq_printf(s, "%s%02x",
1175                                        i == 0 ? "" : " ", pdu_buf[i]);
1176                 if (!ret)
1177                         return ret;
1178
1179                 /*
1180                  * stop when the rest is just zeroes and indicate so
1181                  * with a ".." appended
1182                  */
1183                 if (i == end && end != pdu_len - 1)
1184                         return trace_seq_puts(s, " ..) ");
1185         }
1186
1187         return trace_seq_puts(s, ") ");
1188 }
1189
1190 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1191 {
1192         char cmd[TASK_COMM_LEN];
1193
1194         trace_find_cmdline(ent->pid, cmd);
1195
1196         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1197                 int ret;
1198
1199                 ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1200                 if (!ret)
1201                         return 0;
1202                 ret = blk_log_dump_pdu(s, ent);
1203                 if (!ret)
1204                         return 0;
1205                 return trace_seq_printf(s, "[%s]\n", cmd);
1206         } else {
1207                 if (t_sec(ent))
1208                         return trace_seq_printf(s, "%llu + %u [%s]\n",
1209                                                 t_sector(ent), t_sec(ent), cmd);
1210                 return trace_seq_printf(s, "[%s]\n", cmd);
1211         }
1212 }
1213
1214 static int blk_log_with_error(struct trace_seq *s,
1215                               const struct trace_entry *ent)
1216 {
1217         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1218                 int ret;
1219
1220                 ret = blk_log_dump_pdu(s, ent);
1221                 if (ret)
1222                         return trace_seq_printf(s, "[%d]\n", t_error(ent));
1223                 return 0;
1224         } else {
1225                 if (t_sec(ent))
1226                         return trace_seq_printf(s, "%llu + %u [%d]\n",
1227                                                 t_sector(ent),
1228                                                 t_sec(ent), t_error(ent));
1229                 return trace_seq_printf(s, "%llu [%d]\n",
1230                                         t_sector(ent), t_error(ent));
1231         }
1232 }
1233
1234 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1235 {
1236         struct blk_io_trace_remap r = { .device_from = 0, };
1237
1238         get_pdu_remap(ent, &r);
1239         return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1240                                 t_sector(ent), t_sec(ent),
1241                                 MAJOR(r.device_from), MINOR(r.device_from),
1242                                 (unsigned long long)r.sector_from);
1243 }
1244
1245 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1246 {
1247         char cmd[TASK_COMM_LEN];
1248
1249         trace_find_cmdline(ent->pid, cmd);
1250
1251         return trace_seq_printf(s, "[%s]\n", cmd);
1252 }
1253
1254 static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1255 {
1256         char cmd[TASK_COMM_LEN];
1257
1258         trace_find_cmdline(ent->pid, cmd);
1259
1260         return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1261 }
1262
1263 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1264 {
1265         char cmd[TASK_COMM_LEN];
1266
1267         trace_find_cmdline(ent->pid, cmd);
1268
1269         return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1270                                 get_pdu_int(ent), cmd);
1271 }
1272
1273 static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1274 {
1275         int ret;
1276         const struct blk_io_trace *t = te_blk_io_trace(ent);
1277
1278         ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1279         if (ret)
1280                 return trace_seq_putc(s, '\n');
1281         return ret;
1282 }
1283
1284 /*
1285  * struct tracer operations
1286  */
1287
1288 static void blk_tracer_print_header(struct seq_file *m)
1289 {
1290         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1291                 return;
1292         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1293                     "#  |     |     |           |   |   |\n");
1294 }
1295
1296 static void blk_tracer_start(struct trace_array *tr)
1297 {
1298         blk_tracer_enabled = true;
1299 }
1300
1301 static int blk_tracer_init(struct trace_array *tr)
1302 {
1303         blk_tr = tr;
1304         blk_tracer_start(tr);
1305         return 0;
1306 }
1307
1308 static void blk_tracer_stop(struct trace_array *tr)
1309 {
1310         blk_tracer_enabled = false;
1311 }
1312
1313 static void blk_tracer_reset(struct trace_array *tr)
1314 {
1315         blk_tracer_stop(tr);
1316 }
1317
1318 static const struct {
1319         const char *act[2];
1320         int        (*print)(struct trace_seq *s, const struct trace_entry *ent);
1321 } what2act[] = {
1322         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1323         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1324         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1325         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1326         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1327         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1328         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1329         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1330         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1331         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1332         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1333         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1334         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1335         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1336         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1337 };
1338
1339 static enum print_line_t print_one_line(struct trace_iterator *iter,
1340                                         bool classic)
1341 {
1342         struct trace_seq *s = &iter->seq;
1343         const struct blk_io_trace *t;
1344         u16 what;
1345         int ret;
1346         bool long_act;
1347         blk_log_action_t *log_action;
1348
1349         t          = te_blk_io_trace(iter->ent);
1350         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1351         long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1352         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1353
1354         if (t->action == BLK_TN_MESSAGE) {
1355                 ret = log_action(iter, long_act ? "message" : "m");
1356                 if (ret)
1357                         ret = blk_log_msg(s, iter->ent);
1358                 goto out;
1359         }
1360
1361         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1362                 ret = trace_seq_printf(s, "Unknown action %x\n", what);
1363         else {
1364                 ret = log_action(iter, what2act[what].act[long_act]);
1365                 if (ret)
1366                         ret = what2act[what].print(s, iter->ent);
1367         }
1368 out:
1369         return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1370 }
1371
1372 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1373                                                int flags, struct trace_event *event)
1374 {
1375         return print_one_line(iter, false);
1376 }
1377
1378 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1379 {
1380         struct trace_seq *s = &iter->seq;
1381         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1382         const int offset = offsetof(struct blk_io_trace, sector);
1383         struct blk_io_trace old = {
1384                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1385                 .time     = iter->ts,
1386         };
1387
1388         if (!trace_seq_putmem(s, &old, offset))
1389                 return 0;
1390         return trace_seq_putmem(s, &t->sector,
1391                                 sizeof(old) - offset + t->pdu_len);
1392 }
1393
1394 static enum print_line_t
1395 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1396                              struct trace_event *event)
1397 {
1398         return blk_trace_synthesize_old_trace(iter) ?
1399                         TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1400 }
1401
1402 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1403 {
1404         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1405                 return TRACE_TYPE_UNHANDLED;
1406
1407         return print_one_line(iter, true);
1408 }
1409
1410 static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
1411 {
1412         /* don't output context-info for blk_classic output */
1413         if (bit == TRACE_BLK_OPT_CLASSIC) {
1414                 if (set)
1415                         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1416                 else
1417                         trace_flags |= TRACE_ITER_CONTEXT_INFO;
1418         }
1419         return 0;
1420 }
1421
1422 static struct tracer blk_tracer __read_mostly = {
1423         .name           = "blk",
1424         .init           = blk_tracer_init,
1425         .reset          = blk_tracer_reset,
1426         .start          = blk_tracer_start,
1427         .stop           = blk_tracer_stop,
1428         .print_header   = blk_tracer_print_header,
1429         .print_line     = blk_tracer_print_line,
1430         .flags          = &blk_tracer_flags,
1431         .set_flag       = blk_tracer_set_flag,
1432 };
1433
1434 static struct trace_event_functions trace_blk_event_funcs = {
1435         .trace          = blk_trace_event_print,
1436         .binary         = blk_trace_event_print_binary,
1437 };
1438
1439 static struct trace_event trace_blk_event = {
1440         .type           = TRACE_BLK,
1441         .funcs          = &trace_blk_event_funcs,
1442 };
1443
1444 static int __init init_blk_tracer(void)
1445 {
1446         if (!register_ftrace_event(&trace_blk_event)) {
1447                 pr_warning("Warning: could not register block events\n");
1448                 return 1;
1449         }
1450
1451         if (register_tracer(&blk_tracer) != 0) {
1452                 pr_warning("Warning: could not register the block tracer\n");
1453                 unregister_ftrace_event(&trace_blk_event);
1454                 return 1;
1455         }
1456
1457         return 0;
1458 }
1459
1460 device_initcall(init_blk_tracer);
1461
1462 static int blk_trace_remove_queue(struct request_queue *q)
1463 {
1464         struct blk_trace *bt;
1465
1466         bt = xchg(&q->blk_trace, NULL);
1467         if (bt == NULL)
1468                 return -EINVAL;
1469
1470         if (atomic_dec_and_test(&blk_probes_ref))
1471                 blk_unregister_tracepoints();
1472
1473         blk_trace_free(bt);
1474         return 0;
1475 }
1476
1477 /*
1478  * Setup everything required to start tracing
1479  */
1480 static int blk_trace_setup_queue(struct request_queue *q,
1481                                  struct block_device *bdev)
1482 {
1483         struct blk_trace *old_bt, *bt = NULL;
1484         int ret = -ENOMEM;
1485
1486         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1487         if (!bt)
1488                 return -ENOMEM;
1489
1490         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1491         if (!bt->msg_data)
1492                 goto free_bt;
1493
1494         bt->dev = bdev->bd_dev;
1495         bt->act_mask = (u16)-1;
1496
1497         blk_trace_setup_lba(bt, bdev);
1498
1499         old_bt = xchg(&q->blk_trace, bt);
1500         if (old_bt != NULL) {
1501                 (void)xchg(&q->blk_trace, old_bt);
1502                 ret = -EBUSY;
1503                 goto free_bt;
1504         }
1505
1506         if (atomic_inc_return(&blk_probes_ref) == 1)
1507                 blk_register_tracepoints();
1508         return 0;
1509
1510 free_bt:
1511         blk_trace_free(bt);
1512         return ret;
1513 }
1514
1515 /*
1516  * sysfs interface to enable and configure tracing
1517  */
1518
1519 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1520                                          struct device_attribute *attr,
1521                                          char *buf);
1522 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1523                                           struct device_attribute *attr,
1524                                           const char *buf, size_t count);
1525 #define BLK_TRACE_DEVICE_ATTR(_name) \
1526         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1527                     sysfs_blk_trace_attr_show, \
1528                     sysfs_blk_trace_attr_store)
1529
1530 static BLK_TRACE_DEVICE_ATTR(enable);
1531 static BLK_TRACE_DEVICE_ATTR(act_mask);
1532 static BLK_TRACE_DEVICE_ATTR(pid);
1533 static BLK_TRACE_DEVICE_ATTR(start_lba);
1534 static BLK_TRACE_DEVICE_ATTR(end_lba);
1535
1536 static struct attribute *blk_trace_attrs[] = {
1537         &dev_attr_enable.attr,
1538         &dev_attr_act_mask.attr,
1539         &dev_attr_pid.attr,
1540         &dev_attr_start_lba.attr,
1541         &dev_attr_end_lba.attr,
1542         NULL
1543 };
1544
1545 struct attribute_group blk_trace_attr_group = {
1546         .name  = "trace",
1547         .attrs = blk_trace_attrs,
1548 };
1549
1550 static const struct {
1551         int mask;
1552         const char *str;
1553 } mask_maps[] = {
1554         { BLK_TC_READ,          "read"          },
1555         { BLK_TC_WRITE,         "write"         },
1556         { BLK_TC_FLUSH,         "flush"         },
1557         { BLK_TC_SYNC,          "sync"          },
1558         { BLK_TC_QUEUE,         "queue"         },
1559         { BLK_TC_REQUEUE,       "requeue"       },
1560         { BLK_TC_ISSUE,         "issue"         },
1561         { BLK_TC_COMPLETE,      "complete"      },
1562         { BLK_TC_FS,            "fs"            },
1563         { BLK_TC_PC,            "pc"            },
1564         { BLK_TC_AHEAD,         "ahead"         },
1565         { BLK_TC_META,          "meta"          },
1566         { BLK_TC_DISCARD,       "discard"       },
1567         { BLK_TC_DRV_DATA,      "drv_data"      },
1568         { BLK_TC_FUA,           "fua"           },
1569 };
1570
1571 static int blk_trace_str2mask(const char *str)
1572 {
1573         int i;
1574         int mask = 0;
1575         char *buf, *s, *token;
1576
1577         buf = kstrdup(str, GFP_KERNEL);
1578         if (buf == NULL)
1579                 return -ENOMEM;
1580         s = strstrip(buf);
1581
1582         while (1) {
1583                 token = strsep(&s, ",");
1584                 if (token == NULL)
1585                         break;
1586
1587                 if (*token == '\0')
1588                         continue;
1589
1590                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1591                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1592                                 mask |= mask_maps[i].mask;
1593                                 break;
1594                         }
1595                 }
1596                 if (i == ARRAY_SIZE(mask_maps)) {
1597                         mask = -EINVAL;
1598                         break;
1599                 }
1600         }
1601         kfree(buf);
1602
1603         return mask;
1604 }
1605
1606 static ssize_t blk_trace_mask2str(char *buf, int mask)
1607 {
1608         int i;
1609         char *p = buf;
1610
1611         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1612                 if (mask & mask_maps[i].mask) {
1613                         p += sprintf(p, "%s%s",
1614                                     (p == buf) ? "" : ",", mask_maps[i].str);
1615                 }
1616         }
1617         *p++ = '\n';
1618
1619         return p - buf;
1620 }
1621
1622 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1623 {
1624         if (bdev->bd_disk == NULL)
1625                 return NULL;
1626
1627         return bdev_get_queue(bdev);
1628 }
1629
1630 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1631                                          struct device_attribute *attr,
1632                                          char *buf)
1633 {
1634         struct hd_struct *p = dev_to_part(dev);
1635         struct request_queue *q;
1636         struct block_device *bdev;
1637         ssize_t ret = -ENXIO;
1638
1639         bdev = bdget(part_devt(p));
1640         if (bdev == NULL)
1641                 goto out;
1642
1643         q = blk_trace_get_queue(bdev);
1644         if (q == NULL)
1645                 goto out_bdput;
1646
1647         mutex_lock(&bdev->bd_mutex);
1648
1649         if (attr == &dev_attr_enable) {
1650                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1651                 goto out_unlock_bdev;
1652         }
1653
1654         if (q->blk_trace == NULL)
1655                 ret = sprintf(buf, "disabled\n");
1656         else if (attr == &dev_attr_act_mask)
1657                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1658         else if (attr == &dev_attr_pid)
1659                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1660         else if (attr == &dev_attr_start_lba)
1661                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1662         else if (attr == &dev_attr_end_lba)
1663                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1664
1665 out_unlock_bdev:
1666         mutex_unlock(&bdev->bd_mutex);
1667 out_bdput:
1668         bdput(bdev);
1669 out:
1670         return ret;
1671 }
1672
1673 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1674                                           struct device_attribute *attr,
1675                                           const char *buf, size_t count)
1676 {
1677         struct block_device *bdev;
1678         struct request_queue *q;
1679         struct hd_struct *p;
1680         u64 value;
1681         ssize_t ret = -EINVAL;
1682
1683         if (count == 0)
1684                 goto out;
1685
1686         if (attr == &dev_attr_act_mask) {
1687                 if (sscanf(buf, "%llx", &value) != 1) {
1688                         /* Assume it is a list of trace category names */
1689                         ret = blk_trace_str2mask(buf);
1690                         if (ret < 0)
1691                                 goto out;
1692                         value = ret;
1693                 }
1694         } else if (sscanf(buf, "%llu", &value) != 1)
1695                 goto out;
1696
1697         ret = -ENXIO;
1698
1699         p = dev_to_part(dev);
1700         bdev = bdget(part_devt(p));
1701         if (bdev == NULL)
1702                 goto out;
1703
1704         q = blk_trace_get_queue(bdev);
1705         if (q == NULL)
1706                 goto out_bdput;
1707
1708         mutex_lock(&bdev->bd_mutex);
1709
1710         if (attr == &dev_attr_enable) {
1711                 if (value)
1712                         ret = blk_trace_setup_queue(q, bdev);
1713                 else
1714                         ret = blk_trace_remove_queue(q);
1715                 goto out_unlock_bdev;
1716         }
1717
1718         ret = 0;
1719         if (q->blk_trace == NULL)
1720                 ret = blk_trace_setup_queue(q, bdev);
1721
1722         if (ret == 0) {
1723                 if (attr == &dev_attr_act_mask)
1724                         q->blk_trace->act_mask = value;
1725                 else if (attr == &dev_attr_pid)
1726                         q->blk_trace->pid = value;
1727                 else if (attr == &dev_attr_start_lba)
1728                         q->blk_trace->start_lba = value;
1729                 else if (attr == &dev_attr_end_lba)
1730                         q->blk_trace->end_lba = value;
1731         }
1732
1733 out_unlock_bdev:
1734         mutex_unlock(&bdev->bd_mutex);
1735 out_bdput:
1736         bdput(bdev);
1737 out:
1738         return ret ? ret : count;
1739 }
1740
1741 int blk_trace_init_sysfs(struct device *dev)
1742 {
1743         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1744 }
1745
1746 void blk_trace_remove_sysfs(struct device *dev)
1747 {
1748         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1749 }
1750
1751 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1752
1753 #ifdef CONFIG_EVENT_TRACING
1754
1755 void blk_dump_cmd(char *buf, struct request *rq)
1756 {
1757         int i, end;
1758         int len = rq->cmd_len;
1759         unsigned char *cmd = rq->cmd;
1760
1761         if (rq->cmd_type != REQ_TYPE_BLOCK_PC) {
1762                 buf[0] = '\0';
1763                 return;
1764         }
1765
1766         for (end = len - 1; end >= 0; end--)
1767                 if (cmd[end])
1768                         break;
1769         end++;
1770
1771         for (i = 0; i < len; i++) {
1772                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1773                 if (i == end && end != len - 1) {
1774                         sprintf(buf, " ..");
1775                         break;
1776                 }
1777         }
1778 }
1779
1780 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1781 {
1782         int i = 0;
1783
1784         if (rw & REQ_FLUSH)
1785                 rwbs[i++] = 'F';
1786
1787         if (rw & WRITE)
1788                 rwbs[i++] = 'W';
1789         else if (rw & REQ_DISCARD)
1790                 rwbs[i++] = 'D';
1791         else if (bytes)
1792                 rwbs[i++] = 'R';
1793         else
1794                 rwbs[i++] = 'N';
1795
1796         if (rw & REQ_FUA)
1797                 rwbs[i++] = 'F';
1798         if (rw & REQ_RAHEAD)
1799                 rwbs[i++] = 'A';
1800         if (rw & REQ_SYNC)
1801                 rwbs[i++] = 'S';
1802         if (rw & REQ_META)
1803                 rwbs[i++] = 'M';
1804         if (rw & REQ_SECURE)
1805                 rwbs[i++] = 'E';
1806
1807         rwbs[i] = '\0';
1808 }
1809
1810 #endif /* CONFIG_EVENT_TRACING */
1811