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

Version: ~ [ linux-5.2-rc1 ] ~ [ linux-5.1.2 ] ~ [ linux-5.0.16 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.43 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.119 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.176 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.179 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.139 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.67 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 /*
  2  * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU General Public License version 2 as
  6  * published by the Free Software Foundation.
  7  *
  8  * This program is distributed in the hope that it will be useful,
  9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 11  * GNU General Public License for more details.
 12  *
 13  * You should have received a copy of the GNU General Public License
 14  * along with this program; if not, write to the Free Software
 15  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 16  *
 17  */
 18 #include <linux/kernel.h>
 19 #include <linux/blkdev.h>
 20 #include <linux/blktrace_api.h>
 21 #include <linux/percpu.h>
 22 #include <linux/init.h>
 23 #include <linux/mutex.h>
 24 #include <linux/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 
1768 

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