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powerpc/pmac: Add missing unlocks in error path
[linux-2.6/next.git] / kernel / trace / blktrace.c
blobb3bc91a3f510d089d7ce69ad4b294655dce53ac7
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/smp_lock.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 local_irq_save(flags);
143 buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
144 va_start(args, fmt);
145 n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
146 va_end(args);
147
148 trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
149 local_irq_restore(flags);
150 }
151 EXPORT_SYMBOL_GPL(__trace_note_message);
152
153 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
154 pid_t pid)
155 {
156 if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
157 return 1;
158 if (sector && (sector < bt->start_lba || sector > bt->end_lba))
159 return 1;
160 if (bt->pid && pid != bt->pid)
161 return 1;
162
163 return 0;
164 }
165
166 /*
167 * Data direction bit lookup
168 */
169 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
170 BLK_TC_ACT(BLK_TC_WRITE) };
171
172 /* The ilog2() calls fall out because they're constant */
173 #define MASK_TC_BIT(rw, __name) ((rw & (1 << BIO_RW_ ## __name)) << \
174 (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - BIO_RW_ ## __name))
175
176 /*
177 * The worker for the various blk_add_trace*() types. Fills out a
178 * blk_io_trace structure and places it in a per-cpu subbuffer.
179 */
180 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
181 int rw, u32 what, int error, int pdu_len, void *pdu_data)
182 {
183 struct task_struct *tsk = current;
184 struct ring_buffer_event *event = NULL;
185 struct ring_buffer *buffer = NULL;
186 struct blk_io_trace *t;
187 unsigned long flags = 0;
188 unsigned long *sequence;
189 pid_t pid;
190 int cpu, pc = 0;
191 bool blk_tracer = blk_tracer_enabled;
192
193 if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
194 return;
195
196 what |= ddir_act[rw & WRITE];
197 what |= MASK_TC_BIT(rw, BARRIER);
198 what |= MASK_TC_BIT(rw, SYNCIO);
199 what |= MASK_TC_BIT(rw, AHEAD);
200 what |= MASK_TC_BIT(rw, META);
201 what |= MASK_TC_BIT(rw, DISCARD);
202
203 pid = tsk->pid;
204 if (act_log_check(bt, what, sector, pid))
205 return;
206 cpu = raw_smp_processor_id();
207
208 if (blk_tracer) {
209 tracing_record_cmdline(current);
210
211 buffer = blk_tr->buffer;
212 pc = preempt_count();
213 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
214 sizeof(*t) + pdu_len,
215 0, pc);
216 if (!event)
217 return;
218 t = ring_buffer_event_data(event);
219 goto record_it;
220 }
221
222 /*
223 * A word about the locking here - we disable interrupts to reserve
224 * some space in the relay per-cpu buffer, to prevent an irq
225 * from coming in and stepping on our toes.
226 */
227 local_irq_save(flags);
228
229 if (unlikely(tsk->btrace_seq != blktrace_seq))
230 trace_note_tsk(bt, tsk);
231
232 t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
233 if (t) {
234 sequence = per_cpu_ptr(bt->sequence, cpu);
235
236 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
237 t->sequence = ++(*sequence);
238 t->time = ktime_to_ns(ktime_get());
239 record_it:
240 /*
241 * These two are not needed in ftrace as they are in the
242 * generic trace_entry, filled by tracing_generic_entry_update,
243 * but for the trace_event->bin() synthesizer benefit we do it
244 * here too.
245 */
246 t->cpu = cpu;
247 t->pid = pid;
248
249 t->sector = sector;
250 t->bytes = bytes;
251 t->action = what;
252 t->device = bt->dev;
253 t->error = error;
254 t->pdu_len = pdu_len;
255
256 if (pdu_len)
257 memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
258
259 if (blk_tracer) {
260 trace_buffer_unlock_commit(buffer, event, 0, pc);
261 return;
262 }
263 }
264
265 local_irq_restore(flags);
266 }
267
268 static struct dentry *blk_tree_root;
269 static DEFINE_MUTEX(blk_tree_mutex);
270
271 static void blk_trace_free(struct blk_trace *bt)
272 {
273 debugfs_remove(bt->msg_file);
274 debugfs_remove(bt->dropped_file);
275 relay_close(bt->rchan);
276 debugfs_remove(bt->dir);
277 free_percpu(bt->sequence);
278 free_percpu(bt->msg_data);
279 kfree(bt);
280 }
281
282 static void blk_trace_cleanup(struct blk_trace *bt)
283 {
284 blk_trace_free(bt);
285 if (atomic_dec_and_test(&blk_probes_ref))
286 blk_unregister_tracepoints();
287 }
288
289 int blk_trace_remove(struct request_queue *q)
290 {
291 struct blk_trace *bt;
292
293 bt = xchg(&q->blk_trace, NULL);
294 if (!bt)
295 return -EINVAL;
296
297 if (bt->trace_state != Blktrace_running)
298 blk_trace_cleanup(bt);
299
300 return 0;
301 }
302 EXPORT_SYMBOL_GPL(blk_trace_remove);
303
304 static int blk_dropped_open(struct inode *inode, struct file *filp)
305 {
306 filp->private_data = inode->i_private;
307
308 return 0;
309 }
310
311 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
312 size_t count, loff_t *ppos)
313 {
314 struct blk_trace *bt = filp->private_data;
315 char buf[16];
316
317 snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
318
319 return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
320 }
321
322 static const struct file_operations blk_dropped_fops = {
323 .owner = THIS_MODULE,
324 .open = blk_dropped_open,
325 .read = blk_dropped_read,
326 };
327
328 static int blk_msg_open(struct inode *inode, struct file *filp)
329 {
330 filp->private_data = inode->i_private;
331
332 return 0;
333 }
334
335 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
336 size_t count, loff_t *ppos)
337 {
338 char *msg;
339 struct blk_trace *bt;
340
341 if (count >= BLK_TN_MAX_MSG)
342 return -EINVAL;
343
344 msg = kmalloc(count + 1, GFP_KERNEL);
345 if (msg == NULL)
346 return -ENOMEM;
347
348 if (copy_from_user(msg, buffer, count)) {
349 kfree(msg);
350 return -EFAULT;
351 }
352
353 msg[count] = '\0';
354 bt = filp->private_data;
355 __trace_note_message(bt, "%s", msg);
356 kfree(msg);
357
358 return count;
359 }
360
361 static const struct file_operations blk_msg_fops = {
362 .owner = THIS_MODULE,
363 .open = blk_msg_open,
364 .write = blk_msg_write,
365 };
366
367 /*
368 * Keep track of how many times we encountered a full subbuffer, to aid
369 * the user space app in telling how many lost events there were.
370 */
371 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
372 void *prev_subbuf, size_t prev_padding)
373 {
374 struct blk_trace *bt;
375
376 if (!relay_buf_full(buf))
377 return 1;
378
379 bt = buf->chan->private_data;
380 atomic_inc(&bt->dropped);
381 return 0;
382 }
383
384 static int blk_remove_buf_file_callback(struct dentry *dentry)
385 {
386 debugfs_remove(dentry);
387
388 return 0;
389 }
390
391 static struct dentry *blk_create_buf_file_callback(const char *filename,
392 struct dentry *parent,
393 int mode,
394 struct rchan_buf *buf,
395 int *is_global)
396 {
397 return debugfs_create_file(filename, mode, parent, buf,
398 &relay_file_operations);
399 }
400
401 static struct rchan_callbacks blk_relay_callbacks = {
402 .subbuf_start = blk_subbuf_start_callback,
403 .create_buf_file = blk_create_buf_file_callback,
404 .remove_buf_file = blk_remove_buf_file_callback,
405 };
406
407 static void blk_trace_setup_lba(struct blk_trace *bt,
408 struct block_device *bdev)
409 {
410 struct hd_struct *part = NULL;
411
412 if (bdev)
413 part = bdev->bd_part;
414
415 if (part) {
416 bt->start_lba = part->start_sect;
417 bt->end_lba = part->start_sect + part->nr_sects;
418 } else {
419 bt->start_lba = 0;
420 bt->end_lba = -1ULL;
421 }
422 }
423
424 /*
425 * Setup everything required to start tracing
426 */
427 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
428 struct block_device *bdev,
429 struct blk_user_trace_setup *buts)
430 {
431 struct blk_trace *old_bt, *bt = NULL;
432 struct dentry *dir = NULL;
433 int ret, i;
434
435 if (!buts->buf_size || !buts->buf_nr)
436 return -EINVAL;
437
438 strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
439 buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
440
441 /*
442 * some device names have larger paths - convert the slashes
443 * to underscores for this to work as expected
444 */
445 for (i = 0; i < strlen(buts->name); i++)
446 if (buts->name[i] == '/')
447 buts->name[i] = '_';
448
449 bt = kzalloc(sizeof(*bt), GFP_KERNEL);
450 if (!bt)
451 return -ENOMEM;
452
453 ret = -ENOMEM;
454 bt->sequence = alloc_percpu(unsigned long);
455 if (!bt->sequence)
456 goto err;
457
458 bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
459 if (!bt->msg_data)
460 goto err;
461
462 ret = -ENOENT;
463
464 mutex_lock(&blk_tree_mutex);
465 if (!blk_tree_root) {
466 blk_tree_root = debugfs_create_dir("block", NULL);
467 if (!blk_tree_root) {
468 mutex_unlock(&blk_tree_mutex);
469 goto err;
470 }
471 }
472 mutex_unlock(&blk_tree_mutex);
473
474 dir = debugfs_create_dir(buts->name, blk_tree_root);
475
476 if (!dir)
477 goto err;
478
479 bt->dir = dir;
480 bt->dev = dev;
481 atomic_set(&bt->dropped, 0);
482
483 ret = -EIO;
484 bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
485 &blk_dropped_fops);
486 if (!bt->dropped_file)
487 goto err;
488
489 bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
490 if (!bt->msg_file)
491 goto err;
492
493 bt->rchan = relay_open("trace", dir, buts->buf_size,
494 buts->buf_nr, &blk_relay_callbacks, bt);
495 if (!bt->rchan)
496 goto err;
497
498 bt->act_mask = buts->act_mask;
499 if (!bt->act_mask)
500 bt->act_mask = (u16) -1;
501
502 blk_trace_setup_lba(bt, bdev);
503
504 /* overwrite with user settings */
505 if (buts->start_lba)
506 bt->start_lba = buts->start_lba;
507 if (buts->end_lba)
508 bt->end_lba = buts->end_lba;
509
510 bt->pid = buts->pid;
511 bt->trace_state = Blktrace_setup;
512
513 ret = -EBUSY;
514 old_bt = xchg(&q->blk_trace, bt);
515 if (old_bt) {
516 (void) xchg(&q->blk_trace, old_bt);
517 goto err;
518 }
519
520 if (atomic_inc_return(&blk_probes_ref) == 1)
521 blk_register_tracepoints();
522
523 return 0;
524 err:
525 blk_trace_free(bt);
526 return ret;
527 }
528
529 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
530 struct block_device *bdev,
531 char __user *arg)
532 {
533 struct blk_user_trace_setup buts;
534 int ret;
535
536 ret = copy_from_user(&buts, arg, sizeof(buts));
537 if (ret)
538 return -EFAULT;
539
540 ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
541 if (ret)
542 return ret;
543
544 if (copy_to_user(arg, &buts, sizeof(buts))) {
545 blk_trace_remove(q);
546 return -EFAULT;
547 }
548 return 0;
549 }
550 EXPORT_SYMBOL_GPL(blk_trace_setup);
551
552 int blk_trace_startstop(struct request_queue *q, int start)
553 {
554 int ret;
555 struct blk_trace *bt = q->blk_trace;
556
557 if (bt == NULL)
558 return -EINVAL;
559
560 /*
561 * For starting a trace, we can transition from a setup or stopped
562 * trace. For stopping a trace, the state must be running
563 */
564 ret = -EINVAL;
565 if (start) {
566 if (bt->trace_state == Blktrace_setup ||
567 bt->trace_state == Blktrace_stopped) {
568 blktrace_seq++;
569 smp_mb();
570 bt->trace_state = Blktrace_running;
571
572 trace_note_time(bt);
573 ret = 0;
574 }
575 } else {
576 if (bt->trace_state == Blktrace_running) {
577 bt->trace_state = Blktrace_stopped;
578 relay_flush(bt->rchan);
579 ret = 0;
580 }
581 }
582
583 return ret;
584 }
585 EXPORT_SYMBOL_GPL(blk_trace_startstop);
586
587 /**
588 * blk_trace_ioctl: - handle the ioctls associated with tracing
589 * @bdev: the block device
590 * @cmd: the ioctl cmd
591 * @arg: the argument data, if any
592 *
593 **/
594 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
595 {
596 struct request_queue *q;
597 int ret, start = 0;
598 char b[BDEVNAME_SIZE];
599
600 q = bdev_get_queue(bdev);
601 if (!q)
602 return -ENXIO;
603
604 mutex_lock(&bdev->bd_mutex);
605
606 switch (cmd) {
607 case BLKTRACESETUP:
608 bdevname(bdev, b);
609 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
610 break;
611 case BLKTRACESTART:
612 start = 1;
613 case BLKTRACESTOP:
614 ret = blk_trace_startstop(q, start);
615 break;
616 case BLKTRACETEARDOWN:
617 ret = blk_trace_remove(q);
618 break;
619 default:
620 ret = -ENOTTY;
621 break;
622 }
623
624 mutex_unlock(&bdev->bd_mutex);
625 return ret;
626 }
627
628 /**
629 * blk_trace_shutdown: - stop and cleanup trace structures
630 * @q: the request queue associated with the device
631 *
632 **/
633 void blk_trace_shutdown(struct request_queue *q)
634 {
635 if (q->blk_trace) {
636 blk_trace_startstop(q, 0);
637 blk_trace_remove(q);
638 }
639 }
640
641 /*
642 * blktrace probes
643 */
644
645 /**
646 * blk_add_trace_rq - Add a trace for a request oriented action
647 * @q: queue the io is for
648 * @rq: the source request
649 * @what: the action
650 *
651 * Description:
652 * Records an action against a request. Will log the bio offset + size.
653 *
654 **/
655 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
656 u32 what)
657 {
658 struct blk_trace *bt = q->blk_trace;
659 int rw = rq->cmd_flags & 0x03;
660
661 if (likely(!bt))
662 return;
663
664 if (blk_discard_rq(rq))
665 rw |= (1 << BIO_RW_DISCARD);
666
667 if (blk_pc_request(rq)) {
668 what |= BLK_TC_ACT(BLK_TC_PC);
669 __blk_add_trace(bt, 0, blk_rq_bytes(rq), rw,
670 what, rq->errors, rq->cmd_len, rq->cmd);
671 } else {
672 what |= BLK_TC_ACT(BLK_TC_FS);
673 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), rw,
674 what, rq->errors, 0, NULL);
675 }
676 }
677
678 static void blk_add_trace_rq_abort(struct request_queue *q, struct request *rq)
679 {
680 blk_add_trace_rq(q, rq, BLK_TA_ABORT);
681 }
682
683 static void blk_add_trace_rq_insert(struct request_queue *q, struct request *rq)
684 {
685 blk_add_trace_rq(q, rq, BLK_TA_INSERT);
686 }
687
688 static void blk_add_trace_rq_issue(struct request_queue *q, struct request *rq)
689 {
690 blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
691 }
692
693 static void blk_add_trace_rq_requeue(struct request_queue *q,
694 struct request *rq)
695 {
696 blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
697 }
698
699 static void blk_add_trace_rq_complete(struct request_queue *q,
700 struct request *rq)
701 {
702 blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
703 }
704
705 /**
706 * blk_add_trace_bio - Add a trace for a bio oriented action
707 * @q: queue the io is for
708 * @bio: the source bio
709 * @what: the action
710 *
711 * Description:
712 * Records an action against a bio. Will log the bio offset + size.
713 *
714 **/
715 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
716 u32 what)
717 {
718 struct blk_trace *bt = q->blk_trace;
719
720 if (likely(!bt))
721 return;
722
723 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
724 !bio_flagged(bio, BIO_UPTODATE), 0, NULL);
725 }
726
727 static void blk_add_trace_bio_bounce(struct request_queue *q, struct bio *bio)
728 {
729 blk_add_trace_bio(q, bio, BLK_TA_BOUNCE);
730 }
731
732 static void blk_add_trace_bio_complete(struct request_queue *q, struct bio *bio)
733 {
734 blk_add_trace_bio(q, bio, BLK_TA_COMPLETE);
735 }
736
737 static void blk_add_trace_bio_backmerge(struct request_queue *q,
738 struct bio *bio)
739 {
740 blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
741 }
742
743 static void blk_add_trace_bio_frontmerge(struct request_queue *q,
744 struct bio *bio)
745 {
746 blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
747 }
748
749 static void blk_add_trace_bio_queue(struct request_queue *q, struct bio *bio)
750 {
751 blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
752 }
753
754 static void blk_add_trace_getrq(struct request_queue *q,
755 struct bio *bio, int rw)
756 {
757 if (bio)
758 blk_add_trace_bio(q, bio, BLK_TA_GETRQ);
759 else {
760 struct blk_trace *bt = q->blk_trace;
761
762 if (bt)
763 __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
764 }
765 }
766
767
768 static void blk_add_trace_sleeprq(struct request_queue *q,
769 struct bio *bio, int rw)
770 {
771 if (bio)
772 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ);
773 else {
774 struct blk_trace *bt = q->blk_trace;
775
776 if (bt)
777 __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
778 0, 0, NULL);
779 }
780 }
781
782 static void blk_add_trace_plug(struct request_queue *q)
783 {
784 struct blk_trace *bt = q->blk_trace;
785
786 if (bt)
787 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
788 }
789
790 static void blk_add_trace_unplug_io(struct request_queue *q)
791 {
792 struct blk_trace *bt = q->blk_trace;
793
794 if (bt) {
795 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
796 __be64 rpdu = cpu_to_be64(pdu);
797
798 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_IO, 0,
799 sizeof(rpdu), &rpdu);
800 }
801 }
802
803 static void blk_add_trace_unplug_timer(struct request_queue *q)
804 {
805 struct blk_trace *bt = q->blk_trace;
806
807 if (bt) {
808 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
809 __be64 rpdu = cpu_to_be64(pdu);
810
811 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_TIMER, 0,
812 sizeof(rpdu), &rpdu);
813 }
814 }
815
816 static void blk_add_trace_split(struct request_queue *q, struct bio *bio,
817 unsigned int pdu)
818 {
819 struct blk_trace *bt = q->blk_trace;
820
821 if (bt) {
822 __be64 rpdu = cpu_to_be64(pdu);
823
824 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
825 BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
826 sizeof(rpdu), &rpdu);
827 }
828 }
829
830 /**
831 * blk_add_trace_remap - Add a trace for a remap operation
832 * @q: queue the io is for
833 * @bio: the source bio
834 * @dev: target device
835 * @from: source sector
836 *
837 * Description:
838 * Device mapper or raid target sometimes need to split a bio because
839 * it spans a stripe (or similar). Add a trace for that action.
840 *
841 **/
842 static void blk_add_trace_remap(struct request_queue *q, struct bio *bio,
843 dev_t dev, sector_t from)
844 {
845 struct blk_trace *bt = q->blk_trace;
846 struct blk_io_trace_remap r;
847
848 if (likely(!bt))
849 return;
850
851 r.device_from = cpu_to_be32(dev);
852 r.device_to = cpu_to_be32(bio->bi_bdev->bd_dev);
853 r.sector_from = cpu_to_be64(from);
854
855 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
856 BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE),
857 sizeof(r), &r);
858 }
859
860 /**
861 * blk_add_trace_rq_remap - Add a trace for a request-remap operation
862 * @q: queue the io is for
863 * @rq: the source request
864 * @dev: target device
865 * @from: source sector
866 *
867 * Description:
868 * Device mapper remaps request to other devices.
869 * Add a trace for that action.
870 *
871 **/
872 static void blk_add_trace_rq_remap(struct request_queue *q,
873 struct request *rq, dev_t dev,
874 sector_t from)
875 {
876 struct blk_trace *bt = q->blk_trace;
877 struct blk_io_trace_remap r;
878
879 if (likely(!bt))
880 return;
881
882 r.device_from = cpu_to_be32(dev);
883 r.device_to = cpu_to_be32(disk_devt(rq->rq_disk));
884 r.sector_from = cpu_to_be64(from);
885
886 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
887 rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
888 sizeof(r), &r);
889 }
890
891 /**
892 * blk_add_driver_data - Add binary message with driver-specific data
893 * @q: queue the io is for
894 * @rq: io request
895 * @data: driver-specific data
896 * @len: length of driver-specific data
897 *
898 * Description:
899 * Some drivers might want to write driver-specific data per request.
900 *
901 **/
902 void blk_add_driver_data(struct request_queue *q,
903 struct request *rq,
904 void *data, size_t len)
905 {
906 struct blk_trace *bt = q->blk_trace;
907
908 if (likely(!bt))
909 return;
910
911 if (blk_pc_request(rq))
912 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
913 BLK_TA_DRV_DATA, rq->errors, len, data);
914 else
915 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
916 BLK_TA_DRV_DATA, rq->errors, len, data);
917 }
918 EXPORT_SYMBOL_GPL(blk_add_driver_data);
919
920 static void blk_register_tracepoints(void)
921 {
922 int ret;
923
924 ret = register_trace_block_rq_abort(blk_add_trace_rq_abort);
925 WARN_ON(ret);
926 ret = register_trace_block_rq_insert(blk_add_trace_rq_insert);
927 WARN_ON(ret);
928 ret = register_trace_block_rq_issue(blk_add_trace_rq_issue);
929 WARN_ON(ret);
930 ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue);
931 WARN_ON(ret);
932 ret = register_trace_block_rq_complete(blk_add_trace_rq_complete);
933 WARN_ON(ret);
934 ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce);
935 WARN_ON(ret);
936 ret = register_trace_block_bio_complete(blk_add_trace_bio_complete);
937 WARN_ON(ret);
938 ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
939 WARN_ON(ret);
940 ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
941 WARN_ON(ret);
942 ret = register_trace_block_bio_queue(blk_add_trace_bio_queue);
943 WARN_ON(ret);
944 ret = register_trace_block_getrq(blk_add_trace_getrq);
945 WARN_ON(ret);
946 ret = register_trace_block_sleeprq(blk_add_trace_sleeprq);
947 WARN_ON(ret);
948 ret = register_trace_block_plug(blk_add_trace_plug);
949 WARN_ON(ret);
950 ret = register_trace_block_unplug_timer(blk_add_trace_unplug_timer);
951 WARN_ON(ret);
952 ret = register_trace_block_unplug_io(blk_add_trace_unplug_io);
953 WARN_ON(ret);
954 ret = register_trace_block_split(blk_add_trace_split);
955 WARN_ON(ret);
956 ret = register_trace_block_remap(blk_add_trace_remap);
957 WARN_ON(ret);
958 ret = register_trace_block_rq_remap(blk_add_trace_rq_remap);
959 WARN_ON(ret);
960 }
961
962 static void blk_unregister_tracepoints(void)
963 {
964 unregister_trace_block_rq_remap(blk_add_trace_rq_remap);
965 unregister_trace_block_remap(blk_add_trace_remap);
966 unregister_trace_block_split(blk_add_trace_split);
967 unregister_trace_block_unplug_io(blk_add_trace_unplug_io);
968 unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer);
969 unregister_trace_block_plug(blk_add_trace_plug);
970 unregister_trace_block_sleeprq(blk_add_trace_sleeprq);
971 unregister_trace_block_getrq(blk_add_trace_getrq);
972 unregister_trace_block_bio_queue(blk_add_trace_bio_queue);
973 unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
974 unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
975 unregister_trace_block_bio_complete(blk_add_trace_bio_complete);
976 unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce);
977 unregister_trace_block_rq_complete(blk_add_trace_rq_complete);
978 unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue);
979 unregister_trace_block_rq_issue(blk_add_trace_rq_issue);
980 unregister_trace_block_rq_insert(blk_add_trace_rq_insert);
981 unregister_trace_block_rq_abort(blk_add_trace_rq_abort);
982
983 tracepoint_synchronize_unregister();
984 }
985
986 /*
987 * struct blk_io_tracer formatting routines
988 */
989
990 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
991 {
992 int i = 0;
993 int tc = t->action >> BLK_TC_SHIFT;
994
995 if (t->action == BLK_TN_MESSAGE) {
996 rwbs[i++] = 'N';
997 goto out;
998 }
999
1000 if (tc & BLK_TC_DISCARD)
1001 rwbs[i++] = 'D';
1002 else if (tc & BLK_TC_WRITE)
1003 rwbs[i++] = 'W';
1004 else if (t->bytes)
1005 rwbs[i++] = 'R';
1006 else
1007 rwbs[i++] = 'N';
1008
1009 if (tc & BLK_TC_AHEAD)
1010 rwbs[i++] = 'A';
1011 if (tc & BLK_TC_BARRIER)
1012 rwbs[i++] = 'B';
1013 if (tc & BLK_TC_SYNC)
1014 rwbs[i++] = 'S';
1015 if (tc & BLK_TC_META)
1016 rwbs[i++] = 'M';
1017 out:
1018 rwbs[i] = '\0';
1019 }
1020
1021 static inline
1022 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1023 {
1024 return (const struct blk_io_trace *)ent;
1025 }
1026
1027 static inline const void *pdu_start(const struct trace_entry *ent)
1028 {
1029 return te_blk_io_trace(ent) + 1;
1030 }
1031
1032 static inline u32 t_action(const struct trace_entry *ent)
1033 {
1034 return te_blk_io_trace(ent)->action;
1035 }
1036
1037 static inline u32 t_bytes(const struct trace_entry *ent)
1038 {
1039 return te_blk_io_trace(ent)->bytes;
1040 }
1041
1042 static inline u32 t_sec(const struct trace_entry *ent)
1043 {
1044 return te_blk_io_trace(ent)->bytes >> 9;
1045 }
1046
1047 static inline unsigned long long t_sector(const struct trace_entry *ent)
1048 {
1049 return te_blk_io_trace(ent)->sector;
1050 }
1051
1052 static inline __u16 t_error(const struct trace_entry *ent)
1053 {
1054 return te_blk_io_trace(ent)->error;
1055 }
1056
1057 static __u64 get_pdu_int(const struct trace_entry *ent)
1058 {
1059 const __u64 *val = pdu_start(ent);
1060 return be64_to_cpu(*val);
1061 }
1062
1063 static void get_pdu_remap(const struct trace_entry *ent,
1064 struct blk_io_trace_remap *r)
1065 {
1066 const struct blk_io_trace_remap *__r = pdu_start(ent);
1067 __u64 sector_from = __r->sector_from;
1068
1069 r->device_from = be32_to_cpu(__r->device_from);
1070 r->device_to = be32_to_cpu(__r->device_to);
1071 r->sector_from = be64_to_cpu(sector_from);
1072 }
1073
1074 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1075
1076 static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1077 {
1078 char rwbs[6];
1079 unsigned long long ts = iter->ts;
1080 unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1081 unsigned secs = (unsigned long)ts;
1082 const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1083
1084 fill_rwbs(rwbs, t);
1085
1086 return trace_seq_printf(&iter->seq,
1087 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1088 MAJOR(t->device), MINOR(t->device), iter->cpu,
1089 secs, nsec_rem, iter->ent->pid, act, rwbs);
1090 }
1091
1092 static int blk_log_action(struct trace_iterator *iter, const char *act)
1093 {
1094 char rwbs[6];
1095 const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1096
1097 fill_rwbs(rwbs, t);
1098 return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1099 MAJOR(t->device), MINOR(t->device), act, rwbs);
1100 }
1101
1102 static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1103 {
1104 const unsigned char *pdu_buf;
1105 int pdu_len;
1106 int i, end, ret;
1107
1108 pdu_buf = pdu_start(ent);
1109 pdu_len = te_blk_io_trace(ent)->pdu_len;
1110
1111 if (!pdu_len)
1112 return 1;
1113
1114 /* find the last zero that needs to be printed */
1115 for (end = pdu_len - 1; end >= 0; end--)
1116 if (pdu_buf[end])
1117 break;
1118 end++;
1119
1120 if (!trace_seq_putc(s, '('))
1121 return 0;
1122
1123 for (i = 0; i < pdu_len; i++) {
1124
1125 ret = trace_seq_printf(s, "%s%02x",
1126 i == 0 ? "" : " ", pdu_buf[i]);
1127 if (!ret)
1128 return ret;
1129
1130 /*
1131 * stop when the rest is just zeroes and indicate so
1132 * with a ".." appended
1133 */
1134 if (i == end && end != pdu_len - 1)
1135 return trace_seq_puts(s, " ..) ");
1136 }
1137
1138 return trace_seq_puts(s, ") ");
1139 }
1140
1141 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1142 {
1143 char cmd[TASK_COMM_LEN];
1144
1145 trace_find_cmdline(ent->pid, cmd);
1146
1147 if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1148 int ret;
1149
1150 ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1151 if (!ret)
1152 return 0;
1153 ret = blk_log_dump_pdu(s, ent);
1154 if (!ret)
1155 return 0;
1156 return trace_seq_printf(s, "[%s]\n", cmd);
1157 } else {
1158 if (t_sec(ent))
1159 return trace_seq_printf(s, "%llu + %u [%s]\n",
1160 t_sector(ent), t_sec(ent), cmd);
1161 return trace_seq_printf(s, "[%s]\n", cmd);
1162 }
1163 }
1164
1165 static int blk_log_with_error(struct trace_seq *s,
1166 const struct trace_entry *ent)
1167 {
1168 if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1169 int ret;
1170
1171 ret = blk_log_dump_pdu(s, ent);
1172 if (ret)
1173 return trace_seq_printf(s, "[%d]\n", t_error(ent));
1174 return 0;
1175 } else {
1176 if (t_sec(ent))
1177 return trace_seq_printf(s, "%llu + %u [%d]\n",
1178 t_sector(ent),
1179 t_sec(ent), t_error(ent));
1180 return trace_seq_printf(s, "%llu [%d]\n",
1181 t_sector(ent), t_error(ent));
1182 }
1183 }
1184
1185 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1186 {
1187 struct blk_io_trace_remap r = { .device_from = 0, };
1188
1189 get_pdu_remap(ent, &r);
1190 return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1191 t_sector(ent), t_sec(ent),
1192 MAJOR(r.device_from), MINOR(r.device_from),
1193 (unsigned long long)r.sector_from);
1194 }
1195
1196 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1197 {
1198 char cmd[TASK_COMM_LEN];
1199
1200 trace_find_cmdline(ent->pid, cmd);
1201
1202 return trace_seq_printf(s, "[%s]\n", cmd);
1203 }
1204
1205 static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1206 {
1207 char cmd[TASK_COMM_LEN];
1208
1209 trace_find_cmdline(ent->pid, cmd);
1210
1211 return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1212 }
1213
1214 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1215 {
1216 char cmd[TASK_COMM_LEN];
1217
1218 trace_find_cmdline(ent->pid, cmd);
1219
1220 return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1221 get_pdu_int(ent), cmd);
1222 }
1223
1224 static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1225 {
1226 int ret;
1227 const struct blk_io_trace *t = te_blk_io_trace(ent);
1228
1229 ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1230 if (ret)
1231 return trace_seq_putc(s, '\n');
1232 return ret;
1233 }
1234
1235 /*
1236 * struct tracer operations
1237 */
1238
1239 static void blk_tracer_print_header(struct seq_file *m)
1240 {
1241 if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1242 return;
1243 seq_puts(m, "# DEV CPU TIMESTAMP PID ACT FLG\n"
1244 "# | | | | | |\n");
1245 }
1246
1247 static void blk_tracer_start(struct trace_array *tr)
1248 {
1249 blk_tracer_enabled = true;
1250 }
1251
1252 static int blk_tracer_init(struct trace_array *tr)
1253 {
1254 blk_tr = tr;
1255 blk_tracer_start(tr);
1256 return 0;
1257 }
1258
1259 static void blk_tracer_stop(struct trace_array *tr)
1260 {
1261 blk_tracer_enabled = false;
1262 }
1263
1264 static void blk_tracer_reset(struct trace_array *tr)
1265 {
1266 blk_tracer_stop(tr);
1267 }
1268
1269 static const struct {
1270 const char *act[2];
1271 int (*print)(struct trace_seq *s, const struct trace_entry *ent);
1272 } what2act[] = {
1273 [__BLK_TA_QUEUE] = {{ "Q", "queue" }, blk_log_generic },
1274 [__BLK_TA_BACKMERGE] = {{ "M", "backmerge" }, blk_log_generic },
1275 [__BLK_TA_FRONTMERGE] = {{ "F", "frontmerge" }, blk_log_generic },
1276 [__BLK_TA_GETRQ] = {{ "G", "getrq" }, blk_log_generic },
1277 [__BLK_TA_SLEEPRQ] = {{ "S", "sleeprq" }, blk_log_generic },
1278 [__BLK_TA_REQUEUE] = {{ "R", "requeue" }, blk_log_with_error },
1279 [__BLK_TA_ISSUE] = {{ "D", "issue" }, blk_log_generic },
1280 [__BLK_TA_COMPLETE] = {{ "C", "complete" }, blk_log_with_error },
1281 [__BLK_TA_PLUG] = {{ "P", "plug" }, blk_log_plug },
1282 [__BLK_TA_UNPLUG_IO] = {{ "U", "unplug_io" }, blk_log_unplug },
1283 [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1284 [__BLK_TA_INSERT] = {{ "I", "insert" }, blk_log_generic },
1285 [__BLK_TA_SPLIT] = {{ "X", "split" }, blk_log_split },
1286 [__BLK_TA_BOUNCE] = {{ "B", "bounce" }, blk_log_generic },
1287 [__BLK_TA_REMAP] = {{ "A", "remap" }, blk_log_remap },
1288 };
1289
1290 static enum print_line_t print_one_line(struct trace_iterator *iter,
1291 bool classic)
1292 {
1293 struct trace_seq *s = &iter->seq;
1294 const struct blk_io_trace *t;
1295 u16 what;
1296 int ret;
1297 bool long_act;
1298 blk_log_action_t *log_action;
1299
1300 t = te_blk_io_trace(iter->ent);
1301 what = t->action & ((1 << BLK_TC_SHIFT) - 1);
1302 long_act = !!(trace_flags & TRACE_ITER_VERBOSE);
1303 log_action = classic ? &blk_log_action_classic : &blk_log_action;
1304
1305 if (t->action == BLK_TN_MESSAGE) {
1306 ret = log_action(iter, long_act ? "message" : "m");
1307 if (ret)
1308 ret = blk_log_msg(s, iter->ent);
1309 goto out;
1310 }
1311
1312 if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1313 ret = trace_seq_printf(s, "Unknown action %x\n", what);
1314 else {
1315 ret = log_action(iter, what2act[what].act[long_act]);
1316 if (ret)
1317 ret = what2act[what].print(s, iter->ent);
1318 }
1319 out:
1320 return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1321 }
1322
1323 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1324 int flags)
1325 {
1326 return print_one_line(iter, false);
1327 }
1328
1329 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1330 {
1331 struct trace_seq *s = &iter->seq;
1332 struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1333 const int offset = offsetof(struct blk_io_trace, sector);
1334 struct blk_io_trace old = {
1335 .magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1336 .time = iter->ts,
1337 };
1338
1339 if (!trace_seq_putmem(s, &old, offset))
1340 return 0;
1341 return trace_seq_putmem(s, &t->sector,
1342 sizeof(old) - offset + t->pdu_len);
1343 }
1344
1345 static enum print_line_t
1346 blk_trace_event_print_binary(struct trace_iterator *iter, int flags)
1347 {
1348 return blk_trace_synthesize_old_trace(iter) ?
1349 TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1350 }
1351
1352 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1353 {
1354 if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1355 return TRACE_TYPE_UNHANDLED;
1356
1357 return print_one_line(iter, true);
1358 }
1359
1360 static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
1361 {
1362 /* don't output context-info for blk_classic output */
1363 if (bit == TRACE_BLK_OPT_CLASSIC) {
1364 if (set)
1365 trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1366 else
1367 trace_flags |= TRACE_ITER_CONTEXT_INFO;
1368 }
1369 return 0;
1370 }
1371
1372 static struct tracer blk_tracer __read_mostly = {
1373 .name = "blk",
1374 .init = blk_tracer_init,
1375 .reset = blk_tracer_reset,
1376 .start = blk_tracer_start,
1377 .stop = blk_tracer_stop,
1378 .print_header = blk_tracer_print_header,
1379 .print_line = blk_tracer_print_line,
1380 .flags = &blk_tracer_flags,
1381 .set_flag = blk_tracer_set_flag,
1382 };
1383
1384 static struct trace_event trace_blk_event = {
1385 .type = TRACE_BLK,
1386 .trace = blk_trace_event_print,
1387 .binary = blk_trace_event_print_binary,
1388 };
1389
1390 static int __init init_blk_tracer(void)
1391 {
1392 if (!register_ftrace_event(&trace_blk_event)) {
1393 pr_warning("Warning: could not register block events\n");
1394 return 1;
1395 }
1396
1397 if (register_tracer(&blk_tracer) != 0) {
1398 pr_warning("Warning: could not register the block tracer\n");
1399 unregister_ftrace_event(&trace_blk_event);
1400 return 1;
1401 }
1402
1403 return 0;
1404 }
1405
1406 device_initcall(init_blk_tracer);
1407
1408 static int blk_trace_remove_queue(struct request_queue *q)
1409 {
1410 struct blk_trace *bt;
1411
1412 bt = xchg(&q->blk_trace, NULL);
1413 if (bt == NULL)
1414 return -EINVAL;
1415
1416 if (atomic_dec_and_test(&blk_probes_ref))
1417 blk_unregister_tracepoints();
1418
1419 blk_trace_free(bt);
1420 return 0;
1421 }
1422
1423 /*
1424 * Setup everything required to start tracing
1425 */
1426 static int blk_trace_setup_queue(struct request_queue *q,
1427 struct block_device *bdev)
1428 {
1429 struct blk_trace *old_bt, *bt = NULL;
1430 int ret = -ENOMEM;
1431
1432 bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1433 if (!bt)
1434 return -ENOMEM;
1435
1436 bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1437 if (!bt->msg_data)
1438 goto free_bt;
1439
1440 bt->dev = bdev->bd_dev;
1441 bt->act_mask = (u16)-1;
1442
1443 blk_trace_setup_lba(bt, bdev);
1444
1445 old_bt = xchg(&q->blk_trace, bt);
1446 if (old_bt != NULL) {
1447 (void)xchg(&q->blk_trace, old_bt);
1448 ret = -EBUSY;
1449 goto free_bt;
1450 }
1451
1452 if (atomic_inc_return(&blk_probes_ref) == 1)
1453 blk_register_tracepoints();
1454 return 0;
1455
1456 free_bt:
1457 blk_trace_free(bt);
1458 return ret;
1459 }
1460
1461 /*
1462 * sysfs interface to enable and configure tracing
1463 */
1464
1465 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1466 struct device_attribute *attr,
1467 char *buf);
1468 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1469 struct device_attribute *attr,
1470 const char *buf, size_t count);
1471 #define BLK_TRACE_DEVICE_ATTR(_name) \
1472 DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1473 sysfs_blk_trace_attr_show, \
1474 sysfs_blk_trace_attr_store)
1475
1476 static BLK_TRACE_DEVICE_ATTR(enable);
1477 static BLK_TRACE_DEVICE_ATTR(act_mask);
1478 static BLK_TRACE_DEVICE_ATTR(pid);
1479 static BLK_TRACE_DEVICE_ATTR(start_lba);
1480 static BLK_TRACE_DEVICE_ATTR(end_lba);
1481
1482 static struct attribute *blk_trace_attrs[] = {
1483 &dev_attr_enable.attr,
1484 &dev_attr_act_mask.attr,
1485 &dev_attr_pid.attr,
1486 &dev_attr_start_lba.attr,
1487 &dev_attr_end_lba.attr,
1488 NULL
1489 };
1490
1491 struct attribute_group blk_trace_attr_group = {
1492 .name = "trace",
1493 .attrs = blk_trace_attrs,
1494 };
1495
1496 static const struct {
1497 int mask;
1498 const char *str;
1499 } mask_maps[] = {
1500 { BLK_TC_READ, "read" },
1501 { BLK_TC_WRITE, "write" },
1502 { BLK_TC_BARRIER, "barrier" },
1503 { BLK_TC_SYNC, "sync" },
1504 { BLK_TC_QUEUE, "queue" },
1505 { BLK_TC_REQUEUE, "requeue" },
1506 { BLK_TC_ISSUE, "issue" },
1507 { BLK_TC_COMPLETE, "complete" },
1508 { BLK_TC_FS, "fs" },
1509 { BLK_TC_PC, "pc" },
1510 { BLK_TC_AHEAD, "ahead" },
1511 { BLK_TC_META, "meta" },
1512 { BLK_TC_DISCARD, "discard" },
1513 { BLK_TC_DRV_DATA, "drv_data" },
1514 };
1515
1516 static int blk_trace_str2mask(const char *str)
1517 {
1518 int i;
1519 int mask = 0;
1520 char *buf, *s, *token;
1521
1522 buf = kstrdup(str, GFP_KERNEL);
1523 if (buf == NULL)
1524 return -ENOMEM;
1525 s = strstrip(buf);
1526
1527 while (1) {
1528 token = strsep(&s, ",");
1529 if (token == NULL)
1530 break;
1531
1532 if (*token == '\0')
1533 continue;
1534
1535 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1536 if (strcasecmp(token, mask_maps[i].str) == 0) {
1537 mask |= mask_maps[i].mask;
1538 break;
1539 }
1540 }
1541 if (i == ARRAY_SIZE(mask_maps)) {
1542 mask = -EINVAL;
1543 break;
1544 }
1545 }
1546 kfree(buf);
1547
1548 return mask;
1549 }
1550
1551 static ssize_t blk_trace_mask2str(char *buf, int mask)
1552 {
1553 int i;
1554 char *p = buf;
1555
1556 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1557 if (mask & mask_maps[i].mask) {
1558 p += sprintf(p, "%s%s",
1559 (p == buf) ? "" : ",", mask_maps[i].str);
1560 }
1561 }
1562 *p++ = '\n';
1563
1564 return p - buf;
1565 }
1566
1567 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1568 {
1569 if (bdev->bd_disk == NULL)
1570 return NULL;
1571
1572 return bdev_get_queue(bdev);
1573 }
1574
1575 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1576 struct device_attribute *attr,
1577 char *buf)
1578 {
1579 struct hd_struct *p = dev_to_part(dev);
1580 struct request_queue *q;
1581 struct block_device *bdev;
1582 ssize_t ret = -ENXIO;
1583
1584 lock_kernel();
1585 bdev = bdget(part_devt(p));
1586 if (bdev == NULL)
1587 goto out_unlock_kernel;
1588
1589 q = blk_trace_get_queue(bdev);
1590 if (q == NULL)
1591 goto out_bdput;
1592
1593 mutex_lock(&bdev->bd_mutex);
1594
1595 if (attr == &dev_attr_enable) {
1596 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1597 goto out_unlock_bdev;
1598 }
1599
1600 if (q->blk_trace == NULL)
1601 ret = sprintf(buf, "disabled\n");
1602 else if (attr == &dev_attr_act_mask)
1603 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1604 else if (attr == &dev_attr_pid)
1605 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1606 else if (attr == &dev_attr_start_lba)
1607 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1608 else if (attr == &dev_attr_end_lba)
1609 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1610
1611 out_unlock_bdev:
1612 mutex_unlock(&bdev->bd_mutex);
1613 out_bdput:
1614 bdput(bdev);
1615 out_unlock_kernel:
1616 unlock_kernel();
1617 return ret;
1618 }
1619
1620 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1621 struct device_attribute *attr,
1622 const char *buf, size_t count)
1623 {
1624 struct block_device *bdev;
1625 struct request_queue *q;
1626 struct hd_struct *p;
1627 u64 value;
1628 ssize_t ret = -EINVAL;
1629
1630 if (count == 0)
1631 goto out;
1632
1633 if (attr == &dev_attr_act_mask) {
1634 if (sscanf(buf, "%llx", &value) != 1) {
1635 /* Assume it is a list of trace category names */
1636 ret = blk_trace_str2mask(buf);
1637 if (ret < 0)
1638 goto out;
1639 value = ret;
1640 }
1641 } else if (sscanf(buf, "%llu", &value) != 1)
1642 goto out;
1643
1644 ret = -ENXIO;
1645
1646 lock_kernel();
1647 p = dev_to_part(dev);
1648 bdev = bdget(part_devt(p));
1649 if (bdev == NULL)
1650 goto out_unlock_kernel;
1651
1652 q = blk_trace_get_queue(bdev);
1653 if (q == NULL)
1654 goto out_bdput;
1655
1656 mutex_lock(&bdev->bd_mutex);
1657
1658 if (attr == &dev_attr_enable) {
1659 if (value)
1660 ret = blk_trace_setup_queue(q, bdev);
1661 else
1662 ret = blk_trace_remove_queue(q);
1663 goto out_unlock_bdev;
1664 }
1665
1666 ret = 0;
1667 if (q->blk_trace == NULL)
1668 ret = blk_trace_setup_queue(q, bdev);
1669
1670 if (ret == 0) {
1671 if (attr == &dev_attr_act_mask)
1672 q->blk_trace->act_mask = value;
1673 else if (attr == &dev_attr_pid)
1674 q->blk_trace->pid = value;
1675 else if (attr == &dev_attr_start_lba)
1676 q->blk_trace->start_lba = value;
1677 else if (attr == &dev_attr_end_lba)
1678 q->blk_trace->end_lba = value;
1679 }
1680
1681 out_unlock_bdev:
1682 mutex_unlock(&bdev->bd_mutex);
1683 out_bdput:
1684 bdput(bdev);
1685 out_unlock_kernel:
1686 unlock_kernel();
1687 out:
1688 return ret ? ret : count;
1689 }
1690
1691 int blk_trace_init_sysfs(struct device *dev)
1692 {
1693 return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1694 }
1695
1696 void blk_trace_remove_sysfs(struct device *dev)
1697 {
1698 sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1699 }
1700
1701 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1702
1703 #ifdef CONFIG_EVENT_TRACING
1704
1705 void blk_dump_cmd(char *buf, struct request *rq)
1706 {
1707 int i, end;
1708 int len = rq->cmd_len;
1709 unsigned char *cmd = rq->cmd;
1710
1711 if (!blk_pc_request(rq)) {
1712 buf[0] = '\0';
1713 return;
1714 }
1715
1716 for (end = len - 1; end >= 0; end--)
1717 if (cmd[end])
1718 break;
1719 end++;
1720
1721 for (i = 0; i < len; i++) {
1722 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1723 if (i == end && end != len - 1) {
1724 sprintf(buf, " ..");
1725 break;
1726 }
1727 }
1728 }
1729
1730 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1731 {
1732 int i = 0;
1733
1734 if (rw & WRITE)
1735 rwbs[i++] = 'W';
1736 else if (rw & 1 << BIO_RW_DISCARD)
1737 rwbs[i++] = 'D';
1738 else if (bytes)
1739 rwbs[i++] = 'R';
1740 else
1741 rwbs[i++] = 'N';
1742
1743 if (rw & 1 << BIO_RW_AHEAD)
1744 rwbs[i++] = 'A';
1745 if (rw & 1 << BIO_RW_BARRIER)
1746 rwbs[i++] = 'B';
1747 if (rw & 1 << BIO_RW_SYNCIO)
1748 rwbs[i++] = 'S';
1749 if (rw & 1 << BIO_RW_META)
1750 rwbs[i++] = 'M';
1751
1752 rwbs[i] = '\0';
1753 }
1754
1755 void blk_fill_rwbs_rq(char *rwbs, struct request *rq)
1756 {
1757 int rw = rq->cmd_flags & 0x03;
1758 int bytes;
1759
1760 if (blk_discard_rq(rq))
1761 rw |= (1 << BIO_RW_DISCARD);
1762
1763 bytes = blk_rq_bytes(rq);
1764
1765 blk_fill_rwbs(rwbs, rw, bytes);
1766 }
1767
1768 #endif /* CONFIG_EVENT_TRACING */
1769
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