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On Tue, Nov 06, 2007 at 02:33:53AM -0800, akpm@linux-foundation.org wrote:
[mmotm.git] / kernel / trace / blktrace.c
blobd9d6206e0b148f5c67e5ecda22a7c7992eec76d7
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/debugfs.h>
25 #include <linux/smp_lock.h>
26 #include <linux/time.h>
27 #include <linux/uaccess.h>
28
29 #include <trace/events/block.h>
30
31 #include "trace_output.h"
32
33 #ifdef CONFIG_BLK_DEV_IO_TRACE
34
35 static unsigned int blktrace_seq __read_mostly = 1;
36
37 static struct trace_array *blk_tr;
38 static bool blk_tracer_enabled __read_mostly;
39
40 /* Select an alternative, minimalistic output than the original one */
41 #define TRACE_BLK_OPT_CLASSIC 0x1
42
43 static struct tracer_opt blk_tracer_opts[] = {
44 /* Default disable the minimalistic output */
45 { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
46 { }
47 };
48
49 static struct tracer_flags blk_tracer_flags = {
50 .val = 0,
51 .opts = blk_tracer_opts,
52 };
53
54 /* Global reference count of probes */
55 static atomic_t blk_probes_ref = ATOMIC_INIT(0);
56
57 static void blk_register_tracepoints(void);
58 static void blk_unregister_tracepoints(void);
59
60 /*
61 * Send out a notify message.
62 */
63 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
64 const void *data, size_t len)
65 {
66 struct blk_io_trace *t;
67 struct ring_buffer_event *event = NULL;
68 struct ring_buffer *buffer = NULL;
69 int pc = 0;
70 int cpu = smp_processor_id();
71 bool blk_tracer = blk_tracer_enabled;
72
73 if (blk_tracer) {
74 buffer = blk_tr->buffer;
75 pc = preempt_count();
76 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
77 sizeof(*t) + len,
78 0, pc);
79 if (!event)
80 return;
81 t = ring_buffer_event_data(event);
82 goto record_it;
83 }
84
85 if (!bt->rchan)
86 return;
87
88 t = relay_reserve(bt->rchan, sizeof(*t) + len);
89 if (t) {
90 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
91 t->time = ktime_to_ns(ktime_get());
92 record_it:
93 t->device = bt->dev;
94 t->action = action;
95 t->pid = pid;
96 t->cpu = cpu;
97 t->pdu_len = len;
98 memcpy((void *) t + sizeof(*t), data, len);
99
100 if (blk_tracer)
101 trace_buffer_unlock_commit(buffer, event, 0, pc);
102 }
103 }
104
105 /*
106 * Send out a notify for this process, if we haven't done so since a trace
107 * started
108 */
109 static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
110 {
111 tsk->btrace_seq = blktrace_seq;
112 trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));
113 }
114
115 static void trace_note_time(struct blk_trace *bt)
116 {
117 struct timespec now;
118 unsigned long flags;
119 u32 words[2];
120
121 getnstimeofday(&now);
122 words[0] = now.tv_sec;
123 words[1] = now.tv_nsec;
124
125 local_irq_save(flags);
126 trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
127 local_irq_restore(flags);
128 }
129
130 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
131 {
132 int n;
133 va_list args;
134 unsigned long flags;
135 char *buf;
136
137 if (unlikely(bt->trace_state != Blktrace_running &&
138 !blk_tracer_enabled))
139 return;
140
141 local_irq_save(flags);
142 buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
143 va_start(args, fmt);
144 n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
145 va_end(args);
146
147 trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
148 local_irq_restore(flags);
149 }
150 EXPORT_SYMBOL_GPL(__trace_note_message);
151
152 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
153 pid_t pid)
154 {
155 if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
156 return 1;
157 if (sector && (sector < bt->start_lba || sector > bt->end_lba))
158 return 1;
159 if (bt->pid && pid != bt->pid)
160 return 1;
161
162 return 0;
163 }
164
165 /*
166 * Data direction bit lookup
167 */
168 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
169 BLK_TC_ACT(BLK_TC_WRITE) };
170
171 /* The ilog2() calls fall out because they're constant */
172 #define MASK_TC_BIT(rw, __name) ((rw & (1 << BIO_RW_ ## __name)) << \
173 (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - BIO_RW_ ## __name))
174
175 /*
176 * The worker for the various blk_add_trace*() types. Fills out a
177 * blk_io_trace structure and places it in a per-cpu subbuffer.
178 */
179 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
180 int rw, u32 what, int error, int pdu_len, void *pdu_data)
181 {
182 struct task_struct *tsk = current;
183 struct ring_buffer_event *event = NULL;
184 struct ring_buffer *buffer = NULL;
185 struct blk_io_trace *t;
186 unsigned long flags = 0;
187 unsigned long *sequence;
188 pid_t pid;
189 int cpu, pc = 0;
190 bool blk_tracer = blk_tracer_enabled;
191
192 if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
193 return;
194
195 what |= ddir_act[rw & WRITE];
196 what |= MASK_TC_BIT(rw, BARRIER);
197 what |= MASK_TC_BIT(rw, SYNCIO);
198 what |= MASK_TC_BIT(rw, AHEAD);
199 what |= MASK_TC_BIT(rw, META);
200 what |= MASK_TC_BIT(rw, DISCARD);
201
202 pid = tsk->pid;
203 if (act_log_check(bt, what, sector, pid))
204 return;
205 cpu = raw_smp_processor_id();
206
207 if (blk_tracer) {
208 tracing_record_cmdline(current);
209
210 buffer = blk_tr->buffer;
211 pc = preempt_count();
212 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
213 sizeof(*t) + pdu_len,
214 0, pc);
215 if (!event)
216 return;
217 t = ring_buffer_event_data(event);
218 goto record_it;
219 }
220
221 /*
222 * A word about the locking here - we disable interrupts to reserve
223 * some space in the relay per-cpu buffer, to prevent an irq
224 * from coming in and stepping on our toes.
225 */
226 local_irq_save(flags);
227
228 if (unlikely(tsk->btrace_seq != blktrace_seq))
229 trace_note_tsk(bt, tsk);
230
231 t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
232 if (t) {
233 sequence = per_cpu_ptr(bt->sequence, cpu);
234
235 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
236 t->sequence = ++(*sequence);
237 t->time = ktime_to_ns(ktime_get());
238 record_it:
239 /*
240 * These two are not needed in ftrace as they are in the
241 * generic trace_entry, filled by tracing_generic_entry_update,
242 * but for the trace_event->bin() synthesizer benefit we do it
243 * here too.
244 */
245 t->cpu = cpu;
246 t->pid = pid;
247
248 t->sector = sector;
249 t->bytes = bytes;
250 t->action = what;
251 t->device = bt->dev;
252 t->error = error;
253 t->pdu_len = pdu_len;
254
255 if (pdu_len)
256 memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
257
258 if (blk_tracer) {
259 trace_buffer_unlock_commit(buffer, event, 0, pc);
260 return;
261 }
262 }
263
264 local_irq_restore(flags);
265 }
266
267 static struct dentry *blk_tree_root;
268 static DEFINE_MUTEX(blk_tree_mutex);
269
270 static void blk_trace_free(struct blk_trace *bt)
271 {
272 debugfs_remove(bt->msg_file);
273 debugfs_remove(bt->dropped_file);
274 relay_close(bt->rchan);
275 debugfs_remove(bt->dir);
276 free_percpu(bt->sequence);
277 free_percpu(bt->msg_data);
278 kfree(bt);
279 }
280
281 static void blk_trace_cleanup(struct blk_trace *bt)
282 {
283 blk_trace_free(bt);
284 if (atomic_dec_and_test(&blk_probes_ref))
285 blk_unregister_tracepoints();
286 }
287
288 int blk_trace_remove(struct request_queue *q)
289 {
290 struct blk_trace *bt;
291
292 bt = xchg(&q->blk_trace, NULL);
293 if (!bt)
294 return -EINVAL;
295
296 if (bt->trace_state != Blktrace_running)
297 blk_trace_cleanup(bt);
298
299 return 0;
300 }
301 EXPORT_SYMBOL_GPL(blk_trace_remove);
302
303 static int blk_dropped_open(struct inode *inode, struct file *filp)
304 {
305 filp->private_data = inode->i_private;
306
307 return 0;
308 }
309
310 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
311 size_t count, loff_t *ppos)
312 {
313 struct blk_trace *bt = filp->private_data;
314 char buf[16];
315
316 snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
317
318 return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
319 }
320
321 static const struct file_operations blk_dropped_fops = {
322 .owner = THIS_MODULE,
323 .open = blk_dropped_open,
324 .read = blk_dropped_read,
325 };
326
327 static int blk_msg_open(struct inode *inode, struct file *filp)
328 {
329 filp->private_data = inode->i_private;
330
331 return 0;
332 }
333
334 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
335 size_t count, loff_t *ppos)
336 {
337 char *msg;
338 struct blk_trace *bt;
339
340 if (count >= BLK_TN_MAX_MSG)
341 return -EINVAL;
342
343 msg = kmalloc(count + 1, GFP_KERNEL);
344 if (msg == NULL)
345 return -ENOMEM;
346
347 if (copy_from_user(msg, buffer, count)) {
348 kfree(msg);
349 return -EFAULT;
350 }
351
352 msg[count] = '\0';
353 bt = filp->private_data;
354 __trace_note_message(bt, "%s", msg);
355 kfree(msg);
356
357 return count;
358 }
359
360 static const struct file_operations blk_msg_fops = {
361 .owner = THIS_MODULE,
362 .open = blk_msg_open,
363 .write = blk_msg_write,
364 };
365
366 /*
367 * Keep track of how many times we encountered a full subbuffer, to aid
368 * the user space app in telling how many lost events there were.
369 */
370 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
371 void *prev_subbuf, size_t prev_padding)
372 {
373 struct blk_trace *bt;
374
375 if (!relay_buf_full(buf))
376 return 1;
377
378 bt = buf->chan->private_data;
379 atomic_inc(&bt->dropped);
380 return 0;
381 }
382
383 static int blk_remove_buf_file_callback(struct dentry *dentry)
384 {
385 debugfs_remove(dentry);
386
387 return 0;
388 }
389
390 static struct dentry *blk_create_buf_file_callback(const char *filename,
391 struct dentry *parent,
392 int mode,
393 struct rchan_buf *buf,
394 int *is_global)
395 {
396 return debugfs_create_file(filename, mode, parent, buf,
397 &relay_file_operations);
398 }
399
400 static struct rchan_callbacks blk_relay_callbacks = {
401 .subbuf_start = blk_subbuf_start_callback,
402 .create_buf_file = blk_create_buf_file_callback,
403 .remove_buf_file = blk_remove_buf_file_callback,
404 };
405
406 static void blk_trace_setup_lba(struct blk_trace *bt,
407 struct block_device *bdev)
408 {
409 struct hd_struct *part = NULL;
410
411 if (bdev)
412 part = bdev->bd_part;
413
414 if (part) {
415 bt->start_lba = part->start_sect;
416 bt->end_lba = part->start_sect + part->nr_sects;
417 } else {
418 bt->start_lba = 0;
419 bt->end_lba = -1ULL;
420 }
421 }
422
423 /*
424 * Setup everything required to start tracing
425 */
426 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
427 struct block_device *bdev,
428 struct blk_user_trace_setup *buts)
429 {
430 struct blk_trace *old_bt, *bt = NULL;
431 struct dentry *dir = NULL;
432 int ret, i;
433
434 if (!buts->buf_size || !buts->buf_nr)
435 return -EINVAL;
436
437 strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
438 buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
439
440 /*
441 * some device names have larger paths - convert the slashes
442 * to underscores for this to work as expected
443 */
444 for (i = 0; i < strlen(buts->name); i++)
445 if (buts->name[i] == '/')
446 buts->name[i] = '_';
447
448 bt = kzalloc(sizeof(*bt), GFP_KERNEL);
449 if (!bt)
450 return -ENOMEM;
451
452 ret = -ENOMEM;
453 bt->sequence = alloc_percpu(unsigned long);
454 if (!bt->sequence)
455 goto err;
456
457 bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
458 if (!bt->msg_data)
459 goto err;
460
461 ret = -ENOENT;
462
463 mutex_lock(&blk_tree_mutex);
464 if (!blk_tree_root) {
465 blk_tree_root = debugfs_create_dir("block", NULL);
466 if (!blk_tree_root) {
467 mutex_unlock(&blk_tree_mutex);
468 goto err;
469 }
470 }
471 mutex_unlock(&blk_tree_mutex);
472
473 dir = debugfs_create_dir(buts->name, blk_tree_root);
474
475 if (!dir)
476 goto err;
477
478 bt->dir = dir;
479 bt->dev = dev;
480 atomic_set(&bt->dropped, 0);
481
482 ret = -EIO;
483 bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
484 &blk_dropped_fops);
485 if (!bt->dropped_file)
486 goto err;
487
488 bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
489 if (!bt->msg_file)
490 goto err;
491
492 bt->rchan = relay_open("trace", dir, buts->buf_size,
493 buts->buf_nr, &blk_relay_callbacks, bt);
494 if (!bt->rchan)
495 goto err;
496
497 bt->act_mask = buts->act_mask;
498 if (!bt->act_mask)
499 bt->act_mask = (u16) -1;
500
501 blk_trace_setup_lba(bt, bdev);
502
503 /* overwrite with user settings */
504 if (buts->start_lba)
505 bt->start_lba = buts->start_lba;
506 if (buts->end_lba)
507 bt->end_lba = buts->end_lba;
508
509 bt->pid = buts->pid;
510 bt->trace_state = Blktrace_setup;
511
512 ret = -EBUSY;
513 old_bt = xchg(&q->blk_trace, bt);
514 if (old_bt) {
515 (void) xchg(&q->blk_trace, old_bt);
516 goto err;
517 }
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 return -EFAULT;
545
546 return 0;
547 }
548 EXPORT_SYMBOL_GPL(blk_trace_setup);
549
550 int blk_trace_startstop(struct request_queue *q, int start)
551 {
552 int ret;
553 struct blk_trace *bt = q->blk_trace;
554
555 if (bt == NULL)
556 return -EINVAL;
557
558 /*
559 * For starting a trace, we can transition from a setup or stopped
560 * trace. For stopping a trace, the state must be running
561 */
562 ret = -EINVAL;
563 if (start) {
564 if (bt->trace_state == Blktrace_setup ||
565 bt->trace_state == Blktrace_stopped) {
566 blktrace_seq++;
567 smp_mb();
568 bt->trace_state = Blktrace_running;
569
570 trace_note_time(bt);
571 ret = 0;
572 }
573 } else {
574 if (bt->trace_state == Blktrace_running) {
575 bt->trace_state = Blktrace_stopped;
576 relay_flush(bt->rchan);
577 ret = 0;
578 }
579 }
580
581 return ret;
582 }
583 EXPORT_SYMBOL_GPL(blk_trace_startstop);
584
585 /**
586 * blk_trace_ioctl: - handle the ioctls associated with tracing
587 * @bdev: the block device
588 * @cmd: the ioctl cmd
589 * @arg: the argument data, if any
590 *
591 **/
592 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
593 {
594 struct request_queue *q;
595 int ret, start = 0;
596 char b[BDEVNAME_SIZE];
597
598 q = bdev_get_queue(bdev);
599 if (!q)
600 return -ENXIO;
601
602 mutex_lock(&bdev->bd_mutex);
603
604 switch (cmd) {
605 case BLKTRACESETUP:
606 bdevname(bdev, b);
607 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
608 break;
609 case BLKTRACESTART:
610 start = 1;
611 case BLKTRACESTOP:
612 ret = blk_trace_startstop(q, start);
613 break;
614 case BLKTRACETEARDOWN:
615 ret = blk_trace_remove(q);
616 break;
617 default:
618 ret = -ENOTTY;
619 break;
620 }
621
622 mutex_unlock(&bdev->bd_mutex);
623 return ret;
624 }
625
626 /**
627 * blk_trace_shutdown: - stop and cleanup trace structures
628 * @q: the request queue associated with the device
629 *
630 **/
631 void blk_trace_shutdown(struct request_queue *q)
632 {
633 if (q->blk_trace) {
634 blk_trace_startstop(q, 0);
635 blk_trace_remove(q);
636 }
637 }
638
639 /*
640 * blktrace probes
641 */
642
643 /**
644 * blk_add_trace_rq - Add a trace for a request oriented action
645 * @q: queue the io is for
646 * @rq: the source request
647 * @what: the action
648 *
649 * Description:
650 * Records an action against a request. Will log the bio offset + size.
651 *
652 **/
653 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
654 u32 what)
655 {
656 struct blk_trace *bt = q->blk_trace;
657 int rw = rq->cmd_flags & 0x03;
658
659 if (likely(!bt))
660 return;
661
662 if (blk_discard_rq(rq))
663 rw |= (1 << BIO_RW_DISCARD);
664
665 if (blk_pc_request(rq)) {
666 what |= BLK_TC_ACT(BLK_TC_PC);
667 __blk_add_trace(bt, 0, blk_rq_bytes(rq), rw,
668 what, rq->errors, rq->cmd_len, rq->cmd);
669 } else {
670 what |= BLK_TC_ACT(BLK_TC_FS);
671 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), rw,
672 what, rq->errors, 0, NULL);
673 }
674 }
675
676 static void blk_add_trace_rq_abort(struct request_queue *q, struct request *rq)
677 {
678 blk_add_trace_rq(q, rq, BLK_TA_ABORT);
679 }
680
681 static void blk_add_trace_rq_insert(struct request_queue *q, struct request *rq)
682 {
683 blk_add_trace_rq(q, rq, BLK_TA_INSERT);
684 }
685
686 static void blk_add_trace_rq_issue(struct request_queue *q, struct request *rq)
687 {
688 blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
689 }
690
691 static void blk_add_trace_rq_requeue(struct request_queue *q,
692 struct request *rq)
693 {
694 blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
695 }
696
697 static void blk_add_trace_rq_complete(struct request_queue *q,
698 struct request *rq)
699 {
700 blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
701 }
702
703 /**
704 * blk_add_trace_bio - Add a trace for a bio oriented action
705 * @q: queue the io is for
706 * @bio: the source bio
707 * @what: the action
708 *
709 * Description:
710 * Records an action against a bio. Will log the bio offset + size.
711 *
712 **/
713 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
714 u32 what)
715 {
716 struct blk_trace *bt = q->blk_trace;
717
718 if (likely(!bt))
719 return;
720
721 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
722 !bio_flagged(bio, BIO_UPTODATE), 0, NULL);
723 }
724
725 static void blk_add_trace_bio_bounce(struct request_queue *q, struct bio *bio)
726 {
727 blk_add_trace_bio(q, bio, BLK_TA_BOUNCE);
728 }
729
730 static void blk_add_trace_bio_complete(struct request_queue *q, struct bio *bio)
731 {
732 blk_add_trace_bio(q, bio, BLK_TA_COMPLETE);
733 }
734
735 static void blk_add_trace_bio_backmerge(struct request_queue *q,
736 struct bio *bio)
737 {
738 blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
739 }
740
741 static void blk_add_trace_bio_frontmerge(struct request_queue *q,
742 struct bio *bio)
743 {
744 blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
745 }
746
747 static void blk_add_trace_bio_queue(struct request_queue *q, struct bio *bio)
748 {
749 blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
750 }
751
752 static void blk_add_trace_getrq(struct request_queue *q,
753 struct bio *bio, int rw)
754 {
755 if (bio)
756 blk_add_trace_bio(q, bio, BLK_TA_GETRQ);
757 else {
758 struct blk_trace *bt = q->blk_trace;
759
760 if (bt)
761 __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
762 }
763 }
764
765
766 static void blk_add_trace_sleeprq(struct request_queue *q,
767 struct bio *bio, int rw)
768 {
769 if (bio)
770 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ);
771 else {
772 struct blk_trace *bt = q->blk_trace;
773
774 if (bt)
775 __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
776 0, 0, NULL);
777 }
778 }
779
780 static void blk_add_trace_plug(struct request_queue *q)
781 {
782 struct blk_trace *bt = q->blk_trace;
783
784 if (bt)
785 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
786 }
787
788 static void blk_add_trace_unplug_io(struct request_queue *q)
789 {
790 struct blk_trace *bt = q->blk_trace;
791
792 if (bt) {
793 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
794 __be64 rpdu = cpu_to_be64(pdu);
795
796 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_IO, 0,
797 sizeof(rpdu), &rpdu);
798 }
799 }
800
801 static void blk_add_trace_unplug_timer(struct request_queue *q)
802 {
803 struct blk_trace *bt = q->blk_trace;
804
805 if (bt) {
806 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
807 __be64 rpdu = cpu_to_be64(pdu);
808
809 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_TIMER, 0,
810 sizeof(rpdu), &rpdu);
811 }
812 }
813
814 static void blk_add_trace_split(struct request_queue *q, struct bio *bio,
815 unsigned int pdu)
816 {
817 struct blk_trace *bt = q->blk_trace;
818
819 if (bt) {
820 __be64 rpdu = cpu_to_be64(pdu);
821
822 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
823 BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
824 sizeof(rpdu), &rpdu);
825 }
826 }
827
828 /**
829 * blk_add_trace_remap - Add a trace for a remap operation
830 * @q: queue the io is for
831 * @bio: the source bio
832 * @dev: target device
833 * @from: source sector
834 *
835 * Description:
836 * Device mapper or raid target sometimes need to split a bio because
837 * it spans a stripe (or similar). Add a trace for that action.
838 *
839 **/
840 static void blk_add_trace_remap(struct request_queue *q, struct bio *bio,
841 dev_t dev, sector_t from)
842 {
843 struct blk_trace *bt = q->blk_trace;
844 struct blk_io_trace_remap r;
845
846 if (likely(!bt))
847 return;
848
849 r.device_from = cpu_to_be32(dev);
850 r.device_to = cpu_to_be32(bio->bi_bdev->bd_dev);
851 r.sector_from = cpu_to_be64(from);
852
853 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
854 BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE),
855 sizeof(r), &r);
856 }
857
858 /**
859 * blk_add_trace_rq_remap - Add a trace for a request-remap operation
860 * @q: queue the io is for
861 * @rq: the source request
862 * @dev: target device
863 * @from: source sector
864 *
865 * Description:
866 * Device mapper remaps request to other devices.
867 * Add a trace for that action.
868 *
869 **/
870 static void blk_add_trace_rq_remap(struct request_queue *q,
871 struct request *rq, dev_t dev,
872 sector_t from)
873 {
874 struct blk_trace *bt = q->blk_trace;
875 struct blk_io_trace_remap r;
876
877 if (likely(!bt))
878 return;
879
880 r.device_from = cpu_to_be32(dev);
881 r.device_to = cpu_to_be32(disk_devt(rq->rq_disk));
882 r.sector_from = cpu_to_be64(from);
883
884 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
885 rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
886 sizeof(r), &r);
887 }
888
889 /**
890 * blk_add_driver_data - Add binary message with driver-specific data
891 * @q: queue the io is for
892 * @rq: io request
893 * @data: driver-specific data
894 * @len: length of driver-specific data
895 *
896 * Description:
897 * Some drivers might want to write driver-specific data per request.
898 *
899 **/
900 void blk_add_driver_data(struct request_queue *q,
901 struct request *rq,
902 void *data, size_t len)
903 {
904 struct blk_trace *bt = q->blk_trace;
905
906 if (likely(!bt))
907 return;
908
909 if (blk_pc_request(rq))
910 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
911 BLK_TA_DRV_DATA, rq->errors, len, data);
912 else
913 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
914 BLK_TA_DRV_DATA, rq->errors, len, data);
915 }
916 EXPORT_SYMBOL_GPL(blk_add_driver_data);
917
918 static void blk_register_tracepoints(void)
919 {
920 int ret;
921
922 ret = register_trace_block_rq_abort(blk_add_trace_rq_abort);
923 WARN_ON(ret);
924 ret = register_trace_block_rq_insert(blk_add_trace_rq_insert);
925 WARN_ON(ret);
926 ret = register_trace_block_rq_issue(blk_add_trace_rq_issue);
927 WARN_ON(ret);
928 ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue);
929 WARN_ON(ret);
930 ret = register_trace_block_rq_complete(blk_add_trace_rq_complete);
931 WARN_ON(ret);
932 ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce);
933 WARN_ON(ret);
934 ret = register_trace_block_bio_complete(blk_add_trace_bio_complete);
935 WARN_ON(ret);
936 ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
937 WARN_ON(ret);
938 ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
939 WARN_ON(ret);
940 ret = register_trace_block_bio_queue(blk_add_trace_bio_queue);
941 WARN_ON(ret);
942 ret = register_trace_block_getrq(blk_add_trace_getrq);
943 WARN_ON(ret);
944 ret = register_trace_block_sleeprq(blk_add_trace_sleeprq);
945 WARN_ON(ret);
946 ret = register_trace_block_plug(blk_add_trace_plug);
947 WARN_ON(ret);
948 ret = register_trace_block_unplug_timer(blk_add_trace_unplug_timer);
949 WARN_ON(ret);
950 ret = register_trace_block_unplug_io(blk_add_trace_unplug_io);
951 WARN_ON(ret);
952 ret = register_trace_block_split(blk_add_trace_split);
953 WARN_ON(ret);
954 ret = register_trace_block_remap(blk_add_trace_remap);
955 WARN_ON(ret);
956 ret = register_trace_block_rq_remap(blk_add_trace_rq_remap);
957 WARN_ON(ret);
958 }
959
960 static void blk_unregister_tracepoints(void)
961 {
962 unregister_trace_block_rq_remap(blk_add_trace_rq_remap);
963 unregister_trace_block_remap(blk_add_trace_remap);
964 unregister_trace_block_split(blk_add_trace_split);
965 unregister_trace_block_unplug_io(blk_add_trace_unplug_io);
966 unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer);
967 unregister_trace_block_plug(blk_add_trace_plug);
968 unregister_trace_block_sleeprq(blk_add_trace_sleeprq);
969 unregister_trace_block_getrq(blk_add_trace_getrq);
970 unregister_trace_block_bio_queue(blk_add_trace_bio_queue);
971 unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
972 unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
973 unregister_trace_block_bio_complete(blk_add_trace_bio_complete);
974 unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce);
975 unregister_trace_block_rq_complete(blk_add_trace_rq_complete);
976 unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue);
977 unregister_trace_block_rq_issue(blk_add_trace_rq_issue);
978 unregister_trace_block_rq_insert(blk_add_trace_rq_insert);
979 unregister_trace_block_rq_abort(blk_add_trace_rq_abort);
980
981 tracepoint_synchronize_unregister();
982 }
983
984 /*
985 * struct blk_io_tracer formatting routines
986 */
987
988 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
989 {
990 int i = 0;
991 int tc = t->action >> BLK_TC_SHIFT;
992
993 if (t->action == BLK_TN_MESSAGE) {
994 rwbs[i++] = 'N';
995 goto out;
996 }
997
998 if (tc & BLK_TC_DISCARD)
999 rwbs[i++] = 'D';
1000 else if (tc & BLK_TC_WRITE)
1001 rwbs[i++] = 'W';
1002 else if (t->bytes)
1003 rwbs[i++] = 'R';
1004 else
1005 rwbs[i++] = 'N';
1006
1007 if (tc & BLK_TC_AHEAD)
1008 rwbs[i++] = 'A';
1009 if (tc & BLK_TC_BARRIER)
1010 rwbs[i++] = 'B';
1011 if (tc & BLK_TC_SYNC)
1012 rwbs[i++] = 'S';
1013 if (tc & BLK_TC_META)
1014 rwbs[i++] = 'M';
1015 out:
1016 rwbs[i] = '\0';
1017 }
1018
1019 static inline
1020 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1021 {
1022 return (const struct blk_io_trace *)ent;
1023 }
1024
1025 static inline const void *pdu_start(const struct trace_entry *ent)
1026 {
1027 return te_blk_io_trace(ent) + 1;
1028 }
1029
1030 static inline u32 t_action(const struct trace_entry *ent)
1031 {
1032 return te_blk_io_trace(ent)->action;
1033 }
1034
1035 static inline u32 t_bytes(const struct trace_entry *ent)
1036 {
1037 return te_blk_io_trace(ent)->bytes;
1038 }
1039
1040 static inline u32 t_sec(const struct trace_entry *ent)
1041 {
1042 return te_blk_io_trace(ent)->bytes >> 9;
1043 }
1044
1045 static inline unsigned long long t_sector(const struct trace_entry *ent)
1046 {
1047 return te_blk_io_trace(ent)->sector;
1048 }
1049
1050 static inline __u16 t_error(const struct trace_entry *ent)
1051 {
1052 return te_blk_io_trace(ent)->error;
1053 }
1054
1055 static __u64 get_pdu_int(const struct trace_entry *ent)
1056 {
1057 const __u64 *val = pdu_start(ent);
1058 return be64_to_cpu(*val);
1059 }
1060
1061 static void get_pdu_remap(const struct trace_entry *ent,
1062 struct blk_io_trace_remap *r)
1063 {
1064 const struct blk_io_trace_remap *__r = pdu_start(ent);
1065 __u64 sector_from = __r->sector_from;
1066
1067 r->device_from = be32_to_cpu(__r->device_from);
1068 r->device_to = be32_to_cpu(__r->device_to);
1069 r->sector_from = be64_to_cpu(sector_from);
1070 }
1071
1072 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1073
1074 static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1075 {
1076 char rwbs[6];
1077 unsigned long long ts = iter->ts;
1078 unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1079 unsigned secs = (unsigned long)ts;
1080 const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1081
1082 fill_rwbs(rwbs, t);
1083
1084 return trace_seq_printf(&iter->seq,
1085 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1086 MAJOR(t->device), MINOR(t->device), iter->cpu,
1087 secs, nsec_rem, iter->ent->pid, act, rwbs);
1088 }
1089
1090 static int blk_log_action(struct trace_iterator *iter, const char *act)
1091 {
1092 char rwbs[6];
1093 const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1094
1095 fill_rwbs(rwbs, t);
1096 return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1097 MAJOR(t->device), MINOR(t->device), act, rwbs);
1098 }
1099
1100 static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1101 {
1102 const unsigned char *pdu_buf;
1103 int pdu_len;
1104 int i, end, ret;
1105
1106 pdu_buf = pdu_start(ent);
1107 pdu_len = te_blk_io_trace(ent)->pdu_len;
1108
1109 if (!pdu_len)
1110 return 1;
1111
1112 /* find the last zero that needs to be printed */
1113 for (end = pdu_len - 1; end >= 0; end--)
1114 if (pdu_buf[end])
1115 break;
1116 end++;
1117
1118 if (!trace_seq_putc(s, '('))
1119 return 0;
1120
1121 for (i = 0; i < pdu_len; i++) {
1122
1123 ret = trace_seq_printf(s, "%s%02x",
1124 i == 0 ? "" : " ", pdu_buf[i]);
1125 if (!ret)
1126 return ret;
1127
1128 /*
1129 * stop when the rest is just zeroes and indicate so
1130 * with a ".." appended
1131 */
1132 if (i == end && end != pdu_len - 1)
1133 return trace_seq_puts(s, " ..) ");
1134 }
1135
1136 return trace_seq_puts(s, ") ");
1137 }
1138
1139 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1140 {
1141 char cmd[TASK_COMM_LEN];
1142
1143 trace_find_cmdline(ent->pid, cmd);
1144
1145 if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1146 int ret;
1147
1148 ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1149 if (!ret)
1150 return 0;
1151 ret = blk_log_dump_pdu(s, ent);
1152 if (!ret)
1153 return 0;
1154 return trace_seq_printf(s, "[%s]\n", cmd);
1155 } else {
1156 if (t_sec(ent))
1157 return trace_seq_printf(s, "%llu + %u [%s]\n",
1158 t_sector(ent), t_sec(ent), cmd);
1159 return trace_seq_printf(s, "[%s]\n", cmd);
1160 }
1161 }
1162
1163 static int blk_log_with_error(struct trace_seq *s,
1164 const struct trace_entry *ent)
1165 {
1166 if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1167 int ret;
1168
1169 ret = blk_log_dump_pdu(s, ent);
1170 if (ret)
1171 return trace_seq_printf(s, "[%d]\n", t_error(ent));
1172 return 0;
1173 } else {
1174 if (t_sec(ent))
1175 return trace_seq_printf(s, "%llu + %u [%d]\n",
1176 t_sector(ent),
1177 t_sec(ent), t_error(ent));
1178 return trace_seq_printf(s, "%llu [%d]\n",
1179 t_sector(ent), t_error(ent));
1180 }
1181 }
1182
1183 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1184 {
1185 struct blk_io_trace_remap r = { .device_from = 0, };
1186
1187 get_pdu_remap(ent, &r);
1188 return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1189 t_sector(ent), t_sec(ent),
1190 MAJOR(r.device_from), MINOR(r.device_from),
1191 (unsigned long long)r.sector_from);
1192 }
1193
1194 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1195 {
1196 char cmd[TASK_COMM_LEN];
1197
1198 trace_find_cmdline(ent->pid, cmd);
1199
1200 return trace_seq_printf(s, "[%s]\n", cmd);
1201 }
1202
1203 static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1204 {
1205 char cmd[TASK_COMM_LEN];
1206
1207 trace_find_cmdline(ent->pid, cmd);
1208
1209 return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1210 }
1211
1212 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1213 {
1214 char cmd[TASK_COMM_LEN];
1215
1216 trace_find_cmdline(ent->pid, cmd);
1217
1218 return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1219 get_pdu_int(ent), cmd);
1220 }
1221
1222 static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1223 {
1224 int ret;
1225 const struct blk_io_trace *t = te_blk_io_trace(ent);
1226
1227 ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1228 if (ret)
1229 return trace_seq_putc(s, '\n');
1230 return ret;
1231 }
1232
1233 /*
1234 * struct tracer operations
1235 */
1236
1237 static void blk_tracer_print_header(struct seq_file *m)
1238 {
1239 if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1240 return;
1241 seq_puts(m, "# DEV CPU TIMESTAMP PID ACT FLG\n"
1242 "# | | | | | |\n");
1243 }
1244
1245 static void blk_tracer_start(struct trace_array *tr)
1246 {
1247 blk_tracer_enabled = true;
1248 }
1249
1250 static int blk_tracer_init(struct trace_array *tr)
1251 {
1252 blk_tr = tr;
1253 blk_tracer_start(tr);
1254 return 0;
1255 }
1256
1257 static void blk_tracer_stop(struct trace_array *tr)
1258 {
1259 blk_tracer_enabled = false;
1260 }
1261
1262 static void blk_tracer_reset(struct trace_array *tr)
1263 {
1264 blk_tracer_stop(tr);
1265 }
1266
1267 static const struct {
1268 const char *act[2];
1269 int (*print)(struct trace_seq *s, const struct trace_entry *ent);
1270 } what2act[] = {
1271 [__BLK_TA_QUEUE] = {{ "Q", "queue" }, blk_log_generic },
1272 [__BLK_TA_BACKMERGE] = {{ "M", "backmerge" }, blk_log_generic },
1273 [__BLK_TA_FRONTMERGE] = {{ "F", "frontmerge" }, blk_log_generic },
1274 [__BLK_TA_GETRQ] = {{ "G", "getrq" }, blk_log_generic },
1275 [__BLK_TA_SLEEPRQ] = {{ "S", "sleeprq" }, blk_log_generic },
1276 [__BLK_TA_REQUEUE] = {{ "R", "requeue" }, blk_log_with_error },
1277 [__BLK_TA_ISSUE] = {{ "D", "issue" }, blk_log_generic },
1278 [__BLK_TA_COMPLETE] = {{ "C", "complete" }, blk_log_with_error },
1279 [__BLK_TA_PLUG] = {{ "P", "plug" }, blk_log_plug },
1280 [__BLK_TA_UNPLUG_IO] = {{ "U", "unplug_io" }, blk_log_unplug },
1281 [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1282 [__BLK_TA_INSERT] = {{ "I", "insert" }, blk_log_generic },
1283 [__BLK_TA_SPLIT] = {{ "X", "split" }, blk_log_split },
1284 [__BLK_TA_BOUNCE] = {{ "B", "bounce" }, blk_log_generic },
1285 [__BLK_TA_REMAP] = {{ "A", "remap" }, blk_log_remap },
1286 };
1287
1288 static enum print_line_t print_one_line(struct trace_iterator *iter,
1289 bool classic)
1290 {
1291 struct trace_seq *s = &iter->seq;
1292 const struct blk_io_trace *t;
1293 u16 what;
1294 int ret;
1295 bool long_act;
1296 blk_log_action_t *log_action;
1297
1298 t = te_blk_io_trace(iter->ent);
1299 what = t->action & ((1 << BLK_TC_SHIFT) - 1);
1300 long_act = !!(trace_flags & TRACE_ITER_VERBOSE);
1301 log_action = classic ? &blk_log_action_classic : &blk_log_action;
1302
1303 if (t->action == BLK_TN_MESSAGE) {
1304 ret = log_action(iter, long_act ? "message" : "m");
1305 if (ret)
1306 ret = blk_log_msg(s, iter->ent);
1307 goto out;
1308 }
1309
1310 if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1311 ret = trace_seq_printf(s, "Unknown action %x\n", what);
1312 else {
1313 ret = log_action(iter, what2act[what].act[long_act]);
1314 if (ret)
1315 ret = what2act[what].print(s, iter->ent);
1316 }
1317 out:
1318 return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1319 }
1320
1321 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1322 int flags)
1323 {
1324 return print_one_line(iter, false);
1325 }
1326
1327 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1328 {
1329 struct trace_seq *s = &iter->seq;
1330 struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1331 const int offset = offsetof(struct blk_io_trace, sector);
1332 struct blk_io_trace old = {
1333 .magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1334 .time = iter->ts,
1335 };
1336
1337 if (!trace_seq_putmem(s, &old, offset))
1338 return 0;
1339 return trace_seq_putmem(s, &t->sector,
1340 sizeof(old) - offset + t->pdu_len);
1341 }
1342
1343 static enum print_line_t
1344 blk_trace_event_print_binary(struct trace_iterator *iter, int flags)
1345 {
1346 return blk_trace_synthesize_old_trace(iter) ?
1347 TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1348 }
1349
1350 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1351 {
1352 if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1353 return TRACE_TYPE_UNHANDLED;
1354
1355 return print_one_line(iter, true);
1356 }
1357
1358 static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
1359 {
1360 /* don't output context-info for blk_classic output */
1361 if (bit == TRACE_BLK_OPT_CLASSIC) {
1362 if (set)
1363 trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1364 else
1365 trace_flags |= TRACE_ITER_CONTEXT_INFO;
1366 }
1367 return 0;
1368 }
1369
1370 static struct tracer blk_tracer __read_mostly = {
1371 .name = "blk",
1372 .init = blk_tracer_init,
1373 .reset = blk_tracer_reset,
1374 .start = blk_tracer_start,
1375 .stop = blk_tracer_stop,
1376 .print_header = blk_tracer_print_header,
1377 .print_line = blk_tracer_print_line,
1378 .flags = &blk_tracer_flags,
1379 .set_flag = blk_tracer_set_flag,
1380 };
1381
1382 static struct trace_event trace_blk_event = {
1383 .type = TRACE_BLK,
1384 .trace = blk_trace_event_print,
1385 .binary = blk_trace_event_print_binary,
1386 };
1387
1388 static int __init init_blk_tracer(void)
1389 {
1390 if (!register_ftrace_event(&trace_blk_event)) {
1391 pr_warning("Warning: could not register block events\n");
1392 return 1;
1393 }
1394
1395 if (register_tracer(&blk_tracer) != 0) {
1396 pr_warning("Warning: could not register the block tracer\n");
1397 unregister_ftrace_event(&trace_blk_event);
1398 return 1;
1399 }
1400
1401 return 0;
1402 }
1403
1404 device_initcall(init_blk_tracer);
1405
1406 static int blk_trace_remove_queue(struct request_queue *q)
1407 {
1408 struct blk_trace *bt;
1409
1410 bt = xchg(&q->blk_trace, NULL);
1411 if (bt == NULL)
1412 return -EINVAL;
1413
1414 if (atomic_dec_and_test(&blk_probes_ref))
1415 blk_unregister_tracepoints();
1416
1417 blk_trace_free(bt);
1418 return 0;
1419 }
1420
1421 /*
1422 * Setup everything required to start tracing
1423 */
1424 static int blk_trace_setup_queue(struct request_queue *q,
1425 struct block_device *bdev)
1426 {
1427 struct blk_trace *old_bt, *bt = NULL;
1428 int ret = -ENOMEM;
1429
1430 bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1431 if (!bt)
1432 return -ENOMEM;
1433
1434 bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1435 if (!bt->msg_data)
1436 goto free_bt;
1437
1438 bt->dev = bdev->bd_dev;
1439 bt->act_mask = (u16)-1;
1440
1441 blk_trace_setup_lba(bt, bdev);
1442
1443 old_bt = xchg(&q->blk_trace, bt);
1444 if (old_bt != NULL) {
1445 (void)xchg(&q->blk_trace, old_bt);
1446 ret = -EBUSY;
1447 goto free_bt;
1448 }
1449
1450 if (atomic_inc_return(&blk_probes_ref) == 1)
1451 blk_register_tracepoints();
1452 return 0;
1453
1454 free_bt:
1455 blk_trace_free(bt);
1456 return ret;
1457 }
1458
1459 /*
1460 * sysfs interface to enable and configure tracing
1461 */
1462
1463 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1464 struct device_attribute *attr,
1465 char *buf);
1466 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1467 struct device_attribute *attr,
1468 const char *buf, size_t count);
1469 #define BLK_TRACE_DEVICE_ATTR(_name) \
1470 DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1471 sysfs_blk_trace_attr_show, \
1472 sysfs_blk_trace_attr_store)
1473
1474 static BLK_TRACE_DEVICE_ATTR(enable);
1475 static BLK_TRACE_DEVICE_ATTR(act_mask);
1476 static BLK_TRACE_DEVICE_ATTR(pid);
1477 static BLK_TRACE_DEVICE_ATTR(start_lba);
1478 static BLK_TRACE_DEVICE_ATTR(end_lba);
1479
1480 static struct attribute *blk_trace_attrs[] = {
1481 &dev_attr_enable.attr,
1482 &dev_attr_act_mask.attr,
1483 &dev_attr_pid.attr,
1484 &dev_attr_start_lba.attr,
1485 &dev_attr_end_lba.attr,
1486 NULL
1487 };
1488
1489 struct attribute_group blk_trace_attr_group = {
1490 .name = "trace",
1491 .attrs = blk_trace_attrs,
1492 };
1493
1494 static const struct {
1495 int mask;
1496 const char *str;
1497 } mask_maps[] = {
1498 { BLK_TC_READ, "read" },
1499 { BLK_TC_WRITE, "write" },
1500 { BLK_TC_BARRIER, "barrier" },
1501 { BLK_TC_SYNC, "sync" },
1502 { BLK_TC_QUEUE, "queue" },
1503 { BLK_TC_REQUEUE, "requeue" },
1504 { BLK_TC_ISSUE, "issue" },
1505 { BLK_TC_COMPLETE, "complete" },
1506 { BLK_TC_FS, "fs" },
1507 { BLK_TC_PC, "pc" },
1508 { BLK_TC_AHEAD, "ahead" },
1509 { BLK_TC_META, "meta" },
1510 { BLK_TC_DISCARD, "discard" },
1511 { BLK_TC_DRV_DATA, "drv_data" },
1512 };
1513
1514 static int blk_trace_str2mask(const char *str)
1515 {
1516 int i;
1517 int mask = 0;
1518 char *buf, *s, *token;
1519
1520 buf = kstrdup(str, GFP_KERNEL);
1521 if (buf == NULL)
1522 return -ENOMEM;
1523 s = strstrip(buf);
1524
1525 while (1) {
1526 token = strsep(&s, ",");
1527 if (token == NULL)
1528 break;
1529
1530 if (*token == '\0')
1531 continue;
1532
1533 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1534 if (strcasecmp(token, mask_maps[i].str) == 0) {
1535 mask |= mask_maps[i].mask;
1536 break;
1537 }
1538 }
1539 if (i == ARRAY_SIZE(mask_maps)) {
1540 mask = -EINVAL;
1541 break;
1542 }
1543 }
1544 kfree(buf);
1545
1546 return mask;
1547 }
1548
1549 static ssize_t blk_trace_mask2str(char *buf, int mask)
1550 {
1551 int i;
1552 char *p = buf;
1553
1554 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1555 if (mask & mask_maps[i].mask) {
1556 p += sprintf(p, "%s%s",
1557 (p == buf) ? "" : ",", mask_maps[i].str);
1558 }
1559 }
1560 *p++ = '\n';
1561
1562 return p - buf;
1563 }
1564
1565 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1566 {
1567 if (bdev->bd_disk == NULL)
1568 return NULL;
1569
1570 return bdev_get_queue(bdev);
1571 }
1572
1573 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1574 struct device_attribute *attr,
1575 char *buf)
1576 {
1577 struct hd_struct *p = dev_to_part(dev);
1578 struct request_queue *q;
1579 struct block_device *bdev;
1580 ssize_t ret = -ENXIO;
1581
1582 lock_kernel();
1583 bdev = bdget(part_devt(p));
1584 if (bdev == NULL)
1585 goto out_unlock_kernel;
1586
1587 q = blk_trace_get_queue(bdev);
1588 if (q == NULL)
1589 goto out_bdput;
1590
1591 mutex_lock(&bdev->bd_mutex);
1592
1593 if (attr == &dev_attr_enable) {
1594 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1595 goto out_unlock_bdev;
1596 }
1597
1598 if (q->blk_trace == NULL)
1599 ret = sprintf(buf, "disabled\n");
1600 else if (attr == &dev_attr_act_mask)
1601 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1602 else if (attr == &dev_attr_pid)
1603 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1604 else if (attr == &dev_attr_start_lba)
1605 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1606 else if (attr == &dev_attr_end_lba)
1607 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1608
1609 out_unlock_bdev:
1610 mutex_unlock(&bdev->bd_mutex);
1611 out_bdput:
1612 bdput(bdev);
1613 out_unlock_kernel:
1614 unlock_kernel();
1615 return ret;
1616 }
1617
1618 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1619 struct device_attribute *attr,
1620 const char *buf, size_t count)
1621 {
1622 struct block_device *bdev;
1623 struct request_queue *q;
1624 struct hd_struct *p;
1625 u64 value;
1626 ssize_t ret = -EINVAL;
1627
1628 if (count == 0)
1629 goto out;
1630
1631 if (attr == &dev_attr_act_mask) {
1632 if (sscanf(buf, "%llx", &value) != 1) {
1633 /* Assume it is a list of trace category names */
1634 ret = blk_trace_str2mask(buf);
1635 if (ret < 0)
1636 goto out;
1637 value = ret;
1638 }
1639 } else if (sscanf(buf, "%llu", &value) != 1)
1640 goto out;
1641
1642 ret = -ENXIO;
1643
1644 lock_kernel();
1645 p = dev_to_part(dev);
1646 bdev = bdget(part_devt(p));
1647 if (bdev == NULL)
1648 goto out_unlock_kernel;
1649
1650 q = blk_trace_get_queue(bdev);
1651 if (q == NULL)
1652 goto out_bdput;
1653
1654 mutex_lock(&bdev->bd_mutex);
1655
1656 if (attr == &dev_attr_enable) {
1657 if (value)
1658 ret = blk_trace_setup_queue(q, bdev);
1659 else
1660 ret = blk_trace_remove_queue(q);
1661 goto out_unlock_bdev;
1662 }
1663
1664 ret = 0;
1665 if (q->blk_trace == NULL)
1666 ret = blk_trace_setup_queue(q, bdev);
1667
1668 if (ret == 0) {
1669 if (attr == &dev_attr_act_mask)
1670 q->blk_trace->act_mask = value;
1671 else if (attr == &dev_attr_pid)
1672 q->blk_trace->pid = value;
1673 else if (attr == &dev_attr_start_lba)
1674 q->blk_trace->start_lba = value;
1675 else if (attr == &dev_attr_end_lba)
1676 q->blk_trace->end_lba = value;
1677 }
1678
1679 out_unlock_bdev:
1680 mutex_unlock(&bdev->bd_mutex);
1681 out_bdput:
1682 bdput(bdev);
1683 out_unlock_kernel:
1684 unlock_kernel();
1685 out:
1686 return ret ? ret : count;
1687 }
1688
1689 int blk_trace_init_sysfs(struct device *dev)
1690 {
1691 return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1692 }
1693
1694 void blk_trace_remove_sysfs(struct device *dev)
1695 {
1696 sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1697 }
1698
1699 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1700
1701 #ifdef CONFIG_EVENT_TRACING
1702
1703 void blk_dump_cmd(char *buf, struct request *rq)
1704 {
1705 int i, end;
1706 int len = rq->cmd_len;
1707 unsigned char *cmd = rq->cmd;
1708
1709 if (!blk_pc_request(rq)) {
1710 buf[0] = '\0';
1711 return;
1712 }
1713
1714 for (end = len - 1; end >= 0; end--)
1715 if (cmd[end])
1716 break;
1717 end++;
1718
1719 for (i = 0; i < len; i++) {
1720 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1721 if (i == end && end != len - 1) {
1722 sprintf(buf, " ..");
1723 break;
1724 }
1725 }
1726 }
1727
1728 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1729 {
1730 int i = 0;
1731
1732 if (rw & WRITE)
1733 rwbs[i++] = 'W';
1734 else if (rw & 1 << BIO_RW_DISCARD)
1735 rwbs[i++] = 'D';
1736 else if (bytes)
1737 rwbs[i++] = 'R';
1738 else
1739 rwbs[i++] = 'N';
1740
1741 if (rw & 1 << BIO_RW_AHEAD)
1742 rwbs[i++] = 'A';
1743 if (rw & 1 << BIO_RW_BARRIER)
1744 rwbs[i++] = 'B';
1745 if (rw & 1 << BIO_RW_SYNCIO)
1746 rwbs[i++] = 'S';
1747 if (rw & 1 << BIO_RW_META)
1748 rwbs[i++] = 'M';
1749
1750 rwbs[i] = '\0';
1751 }
1752
1753 void blk_fill_rwbs_rq(char *rwbs, struct request *rq)
1754 {
1755 int rw = rq->cmd_flags & 0x03;
1756 int bytes;
1757
1758 if (blk_discard_rq(rq))
1759 rw |= (1 << BIO_RW_DISCARD);
1760
1761 bytes = blk_rq_bytes(rq);
1762
1763 blk_fill_rwbs(rwbs, rw, bytes);
1764 }
1765
1766 #endif /* CONFIG_EVENT_TRACING */
1767
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