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

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  1 /*
  2  * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU General Public License version 2 as
  6  * published by the Free Software Foundation.
  7  *
  8  * This program is distributed in the hope that it will be useful,
  9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 11  * GNU General Public License for more details.
 12  *
 13  * You should have received a copy of the GNU General Public License
 14  * along with this program; if not, write to the Free Software
 15  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 16  *
 17  */
 18 #include <linux/kernel.h>
 19 #include <linux/blkdev.h>
 20 #include <linux/blktrace_api.h>
 21 #include <linux/percpu.h>
 22 #include <linux/init.h>
 23 #include <linux/mutex.h>
 24 #include <linux/slab.h>
 25 #include <linux/debugfs.h>
 26 #include <linux/export.h>
 27 #include <linux/time.h>
 28 #include <linux/uaccess.h>
 29 #include <linux/list.h>
 30 
 31 #include <trace/events/block.h>
 32 
 33 #include "trace_output.h"
 34 
 35 #ifdef CONFIG_BLK_DEV_IO_TRACE
 36 
 37 static unsigned int blktrace_seq __read_mostly = 1;
 38 
 39 static struct trace_array *blk_tr;
 40 static bool blk_tracer_enabled __read_mostly;
 41 
 42 static LIST_HEAD(running_trace_list);
 43 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock);
 44 
 45 /* Select an alternative, minimalistic output than the original one */
 46 #define TRACE_BLK_OPT_CLASSIC   0x1
 47 
 48 static struct tracer_opt blk_tracer_opts[] = {
 49         /* Default disable the minimalistic output */
 50         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
 51         { }
 52 };
 53 
 54 static struct tracer_flags blk_tracer_flags = {
 55         .val  = 0,
 56         .opts = blk_tracer_opts,
 57 };
 58 
 59 /* Global reference count of probes */
 60 static atomic_t blk_probes_ref = ATOMIC_INIT(0);
 61 
 62 static void blk_register_tracepoints(void);
 63 static void blk_unregister_tracepoints(void);
 64 
 65 /*
 66  * Send out a notify message.
 67  */
 68 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 69                        const void *data, size_t len)
 70 {
 71         struct blk_io_trace *t;
 72         struct ring_buffer_event *event = NULL;
 73         struct ring_buffer *buffer = NULL;
 74         int pc = 0;
 75         int cpu = smp_processor_id();
 76         bool blk_tracer = blk_tracer_enabled;
 77 
 78         if (blk_tracer) {
 79                 buffer = blk_tr->trace_buffer.buffer;
 80                 pc = preempt_count();
 81                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 82                                                   sizeof(*t) + len,
 83                                                   0, pc);
 84                 if (!event)
 85                         return;
 86                 t = ring_buffer_event_data(event);
 87                 goto record_it;
 88         }
 89 
 90         if (!bt->rchan)
 91                 return;
 92 
 93         t = relay_reserve(bt->rchan, sizeof(*t) + len);
 94         if (t) {
 95                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 96                 t->time = ktime_to_ns(ktime_get());
 97 record_it:
 98                 t->device = bt->dev;
 99                 t->action = action;
100                 t->pid = pid;
101                 t->cpu = cpu;
102                 t->pdu_len = len;
103                 memcpy((void *) t + sizeof(*t), data, len);
104 
105                 if (blk_tracer)
106                         trace_buffer_unlock_commit(buffer, event, 0, pc);
107         }
108 }
109 
110 /*
111  * Send out a notify for this process, if we haven't done so since a trace
112  * started
113  */
114 static void trace_note_tsk(struct task_struct *tsk)
115 {
116         unsigned long flags;
117         struct blk_trace *bt;
118 
119         tsk->btrace_seq = blktrace_seq;
120         spin_lock_irqsave(&running_trace_lock, flags);
121         list_for_each_entry(bt, &running_trace_list, running_list) {
122                 trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm,
123                            sizeof(tsk->comm));
124         }
125         spin_unlock_irqrestore(&running_trace_lock, flags);
126 }
127 
128 static void trace_note_time(struct blk_trace *bt)
129 {
130         struct timespec now;
131         unsigned long flags;
132         u32 words[2];
133 
134         getnstimeofday(&now);
135         words[0] = now.tv_sec;
136         words[1] = now.tv_nsec;
137 
138         local_irq_save(flags);
139         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
140         local_irq_restore(flags);
141 }
142 
143 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
144 {
145         int n;
146         va_list args;
147         unsigned long flags;
148         char *buf;
149 
150         if (unlikely(bt->trace_state != Blktrace_running &&
151                      !blk_tracer_enabled))
152                 return;
153 
154         /*
155          * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
156          * message to the trace.
157          */
158         if (!(bt->act_mask & BLK_TC_NOTIFY))
159                 return;
160 
161         local_irq_save(flags);
162         buf = this_cpu_ptr(bt->msg_data);
163         va_start(args, fmt);
164         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
165         va_end(args);
166 
167         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
168         local_irq_restore(flags);
169 }
170 EXPORT_SYMBOL_GPL(__trace_note_message);
171 
172 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
173                          pid_t pid)
174 {
175         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
176                 return 1;
177         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
178                 return 1;
179         if (bt->pid && pid != bt->pid)
180                 return 1;
181 
182         return 0;
183 }
184 
185 /*
186  * Data direction bit lookup
187  */
188 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
189                                  BLK_TC_ACT(BLK_TC_WRITE) };
190 
191 #define BLK_TC_RAHEAD           BLK_TC_AHEAD
192 
193 /* The ilog2() calls fall out because they're constant */
194 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
195           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
196 
197 /*
198  * The worker for the various blk_add_trace*() types. Fills out a
199  * blk_io_trace structure and places it in a per-cpu subbuffer.
200  */
201 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
202                      int rw, u32 what, int error, int pdu_len, void *pdu_data)
203 {
204         struct task_struct *tsk = current;
205         struct ring_buffer_event *event = NULL;
206         struct ring_buffer *buffer = NULL;
207         struct blk_io_trace *t;
208         unsigned long flags = 0;
209         unsigned long *sequence;
210         pid_t pid;
211         int cpu, pc = 0;
212         bool blk_tracer = blk_tracer_enabled;
213 
214         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
215                 return;
216 
217         what |= ddir_act[rw & WRITE];
218         what |= MASK_TC_BIT(rw, SYNC);
219         what |= MASK_TC_BIT(rw, RAHEAD);
220         what |= MASK_TC_BIT(rw, META);
221         what |= MASK_TC_BIT(rw, DISCARD);
222         what |= MASK_TC_BIT(rw, FLUSH);
223         what |= MASK_TC_BIT(rw, FUA);
224 
225         pid = tsk->pid;
226         if (act_log_check(bt, what, sector, pid))
227                 return;
228         cpu = raw_smp_processor_id();
229 
230         if (blk_tracer) {
231                 tracing_record_cmdline(current);
232 
233                 buffer = blk_tr->trace_buffer.buffer;
234                 pc = preempt_count();
235                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
236                                                   sizeof(*t) + pdu_len,
237                                                   0, pc);
238                 if (!event)
239                         return;
240                 t = ring_buffer_event_data(event);
241                 goto record_it;
242         }
243 
244         if (unlikely(tsk->btrace_seq != blktrace_seq))
245                 trace_note_tsk(tsk);
246 
247         /*
248          * A word about the locking here - we disable interrupts to reserve
249          * some space in the relay per-cpu buffer, to prevent an irq
250          * from coming in and stepping on our toes.
251          */
252         local_irq_save(flags);
253         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
254         if (t) {
255                 sequence = per_cpu_ptr(bt->sequence, cpu);
256 
257                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
258                 t->sequence = ++(*sequence);
259                 t->time = ktime_to_ns(ktime_get());
260 record_it:
261                 /*
262                  * These two are not needed in ftrace as they are in the
263                  * generic trace_entry, filled by tracing_generic_entry_update,
264                  * but for the trace_event->bin() synthesizer benefit we do it
265                  * here too.
266                  */
267                 t->cpu = cpu;
268                 t->pid = pid;
269 
270                 t->sector = sector;
271                 t->bytes = bytes;
272                 t->action = what;
273                 t->device = bt->dev;
274                 t->error = error;
275                 t->pdu_len = pdu_len;
276 
277                 if (pdu_len)
278                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
279 
280                 if (blk_tracer) {
281                         trace_buffer_unlock_commit(buffer, event, 0, pc);
282                         return;
283                 }
284         }
285 
286         local_irq_restore(flags);
287 }
288 
289 static struct dentry *blk_tree_root;
290 static DEFINE_MUTEX(blk_tree_mutex);
291 
292 static void blk_trace_free(struct blk_trace *bt)
293 {
294         debugfs_remove(bt->msg_file);
295         debugfs_remove(bt->dropped_file);
296         relay_close(bt->rchan);
297         debugfs_remove(bt->dir);
298         free_percpu(bt->sequence);
299         free_percpu(bt->msg_data);
300         kfree(bt);
301 }
302 
303 static void blk_trace_cleanup(struct blk_trace *bt)
304 {
305         blk_trace_free(bt);
306         if (atomic_dec_and_test(&blk_probes_ref))
307                 blk_unregister_tracepoints();
308 }
309 
310 int blk_trace_remove(struct request_queue *q)
311 {
312         struct blk_trace *bt;
313 
314         bt = xchg(&q->blk_trace, NULL);
315         if (!bt)
316                 return -EINVAL;
317 
318         if (bt->trace_state != Blktrace_running)
319                 blk_trace_cleanup(bt);
320 
321         return 0;
322 }
323 EXPORT_SYMBOL_GPL(blk_trace_remove);
324 
325 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
326                                 size_t count, loff_t *ppos)
327 {
328         struct blk_trace *bt = filp->private_data;
329         char buf[16];
330 
331         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
332 
333         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
334 }
335 
336 static const struct file_operations blk_dropped_fops = {
337         .owner =        THIS_MODULE,
338         .open =         simple_open,
339         .read =         blk_dropped_read,
340         .llseek =       default_llseek,
341 };
342 
343 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
344                                 size_t count, loff_t *ppos)
345 {
346         char *msg;
347         struct blk_trace *bt;
348 
349         if (count >= BLK_TN_MAX_MSG)
350                 return -EINVAL;
351 
352         msg = kmalloc(count + 1, GFP_KERNEL);
353         if (msg == NULL)
354                 return -ENOMEM;
355 
356         if (copy_from_user(msg, buffer, count)) {
357                 kfree(msg);
358                 return -EFAULT;
359         }
360 
361         msg[count] = '\0';
362         bt = filp->private_data;
363         __trace_note_message(bt, "%s", msg);
364         kfree(msg);
365 
366         return count;
367 }
368 
369 static const struct file_operations blk_msg_fops = {
370         .owner =        THIS_MODULE,
371         .open =         simple_open,
372         .write =        blk_msg_write,
373         .llseek =       noop_llseek,
374 };
375 
376 /*
377  * Keep track of how many times we encountered a full subbuffer, to aid
378  * the user space app in telling how many lost events there were.
379  */
380 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
381                                      void *prev_subbuf, size_t prev_padding)
382 {
383         struct blk_trace *bt;
384 
385         if (!relay_buf_full(buf))
386                 return 1;
387 
388         bt = buf->chan->private_data;
389         atomic_inc(&bt->dropped);
390         return 0;
391 }
392 
393 static int blk_remove_buf_file_callback(struct dentry *dentry)
394 {
395         debugfs_remove(dentry);
396 
397         return 0;
398 }
399 
400 static struct dentry *blk_create_buf_file_callback(const char *filename,
401                                                    struct dentry *parent,
402                                                    umode_t mode,
403                                                    struct rchan_buf *buf,
404                                                    int *is_global)
405 {
406         return debugfs_create_file(filename, mode, parent, buf,
407                                         &relay_file_operations);
408 }
409 
410 static struct rchan_callbacks blk_relay_callbacks = {
411         .subbuf_start           = blk_subbuf_start_callback,
412         .create_buf_file        = blk_create_buf_file_callback,
413         .remove_buf_file        = blk_remove_buf_file_callback,
414 };
415 
416 static void blk_trace_setup_lba(struct blk_trace *bt,
417                                 struct block_device *bdev)
418 {
419         struct hd_struct *part = NULL;
420 
421         if (bdev)
422                 part = bdev->bd_part;
423 
424         if (part) {
425                 bt->start_lba = part->start_sect;
426                 bt->end_lba = part->start_sect + part->nr_sects;
427         } else {
428                 bt->start_lba = 0;
429                 bt->end_lba = -1ULL;
430         }
431 }
432 
433 /*
434  * Setup everything required to start tracing
435  */
436 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
437                        struct block_device *bdev,
438                        struct blk_user_trace_setup *buts)
439 {
440         struct blk_trace *old_bt, *bt = NULL;
441         struct dentry *dir = NULL;
442         int ret, i;
443 
444         if (!buts->buf_size || !buts->buf_nr)
445                 return -EINVAL;
446 
447         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
448         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
449 
450         /*
451          * some device names have larger paths - convert the slashes
452          * to underscores for this to work as expected
453          */
454         for (i = 0; i < strlen(buts->name); i++)
455                 if (buts->name[i] == '/')
456                         buts->name[i] = '_';
457 
458         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
459         if (!bt)
460                 return -ENOMEM;
461 
462         ret = -ENOMEM;
463         bt->sequence = alloc_percpu(unsigned long);
464         if (!bt->sequence)
465                 goto err;
466 
467         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
468         if (!bt->msg_data)
469                 goto err;
470 
471         ret = -ENOENT;
472 
473         mutex_lock(&blk_tree_mutex);
474         if (!blk_tree_root) {
475                 blk_tree_root = debugfs_create_dir("block", NULL);
476                 if (!blk_tree_root) {
477                         mutex_unlock(&blk_tree_mutex);
478                         goto err;
479                 }
480         }
481         mutex_unlock(&blk_tree_mutex);
482 
483         dir = debugfs_create_dir(buts->name, blk_tree_root);
484 
485         if (!dir)
486                 goto err;
487 
488         bt->dir = dir;
489         bt->dev = dev;
490         atomic_set(&bt->dropped, 0);
491         INIT_LIST_HEAD(&bt->running_list);
492 
493         ret = -EIO;
494         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
495                                                &blk_dropped_fops);
496         if (!bt->dropped_file)
497                 goto err;
498 
499         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
500         if (!bt->msg_file)
501                 goto err;
502 
503         bt->rchan = relay_open("trace", dir, buts->buf_size,
504                                 buts->buf_nr, &blk_relay_callbacks, bt);
505         if (!bt->rchan)
506                 goto err;
507 
508         bt->act_mask = buts->act_mask;
509         if (!bt->act_mask)
510                 bt->act_mask = (u16) -1;
511 
512         blk_trace_setup_lba(bt, bdev);
513 
514         /* overwrite with user settings */
515         if (buts->start_lba)
516                 bt->start_lba = buts->start_lba;
517         if (buts->end_lba)
518                 bt->end_lba = buts->end_lba;
519 
520         bt->pid = buts->pid;
521         bt->trace_state = Blktrace_setup;
522 
523         ret = -EBUSY;
524         old_bt = xchg(&q->blk_trace, bt);
525         if (old_bt) {
526                 (void) xchg(&q->blk_trace, old_bt);
527                 goto err;
528         }
529 
530         if (atomic_inc_return(&blk_probes_ref) == 1)
531                 blk_register_tracepoints();
532 
533         return 0;
534 err:
535         blk_trace_free(bt);
536         return ret;
537 }
538 
539 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
540                     struct block_device *bdev,
541                     char __user *arg)
542 {
543         struct blk_user_trace_setup buts;
544         int ret;
545 
546         ret = copy_from_user(&buts, arg, sizeof(buts));
547         if (ret)
548                 return -EFAULT;
549 
550         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
551         if (ret)
552                 return ret;
553 
554         if (copy_to_user(arg, &buts, sizeof(buts))) {
555                 blk_trace_remove(q);
556                 return -EFAULT;
557         }
558         return 0;
559 }
560 EXPORT_SYMBOL_GPL(blk_trace_setup);
561 
562 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
563 static int compat_blk_trace_setup(struct request_queue *q, char *name,
564                                   dev_t dev, struct block_device *bdev,
565                                   char __user *arg)
566 {
567         struct blk_user_trace_setup buts;
568         struct compat_blk_user_trace_setup cbuts;
569         int ret;
570 
571         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
572                 return -EFAULT;
573 
574         buts = (struct blk_user_trace_setup) {
575                 .act_mask = cbuts.act_mask,
576                 .buf_size = cbuts.buf_size,
577                 .buf_nr = cbuts.buf_nr,
578                 .start_lba = cbuts.start_lba,
579                 .end_lba = cbuts.end_lba,
580                 .pid = cbuts.pid,
581         };
582 
583         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
584         if (ret)
585                 return ret;
586 
587         if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
588                 blk_trace_remove(q);
589                 return -EFAULT;
590         }
591 
592         return 0;
593 }
594 #endif
595 
596 int blk_trace_startstop(struct request_queue *q, int start)
597 {
598         int ret;
599         struct blk_trace *bt = q->blk_trace;
600 
601         if (bt == NULL)
602                 return -EINVAL;
603 
604         /*
605          * For starting a trace, we can transition from a setup or stopped
606          * trace. For stopping a trace, the state must be running
607          */
608         ret = -EINVAL;
609         if (start) {
610                 if (bt->trace_state == Blktrace_setup ||
611                     bt->trace_state == Blktrace_stopped) {
612                         blktrace_seq++;
613                         smp_mb();
614                         bt->trace_state = Blktrace_running;
615                         spin_lock_irq(&running_trace_lock);
616                         list_add(&bt->running_list, &running_trace_list);
617                         spin_unlock_irq(&running_trace_lock);
618 
619                         trace_note_time(bt);
620                         ret = 0;
621                 }
622         } else {
623                 if (bt->trace_state == Blktrace_running) {
624                         bt->trace_state = Blktrace_stopped;
625                         spin_lock_irq(&running_trace_lock);
626                         list_del_init(&bt->running_list);
627                         spin_unlock_irq(&running_trace_lock);
628                         relay_flush(bt->rchan);
629                         ret = 0;
630                 }
631         }
632 
633         return ret;
634 }
635 EXPORT_SYMBOL_GPL(blk_trace_startstop);
636 
637 /**
638  * blk_trace_ioctl: - handle the ioctls associated with tracing
639  * @bdev:       the block device
640  * @cmd:        the ioctl cmd
641  * @arg:        the argument data, if any
642  *
643  **/
644 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
645 {
646         struct request_queue *q;
647         int ret, start = 0;
648         char b[BDEVNAME_SIZE];
649 
650         q = bdev_get_queue(bdev);
651         if (!q)
652                 return -ENXIO;
653 
654         mutex_lock(&bdev->bd_mutex);
655 
656         switch (cmd) {
657         case BLKTRACESETUP:
658                 bdevname(bdev, b);
659                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
660                 break;
661 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
662         case BLKTRACESETUP32:
663                 bdevname(bdev, b);
664                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
665                 break;
666 #endif
667         case BLKTRACESTART:
668                 start = 1;
669         case BLKTRACESTOP:
670                 ret = blk_trace_startstop(q, start);
671                 break;
672         case BLKTRACETEARDOWN:
673                 ret = blk_trace_remove(q);
674                 break;
675         default:
676                 ret = -ENOTTY;
677                 break;
678         }
679 
680         mutex_unlock(&bdev->bd_mutex);
681         return ret;
682 }
683 
684 /**
685  * blk_trace_shutdown: - stop and cleanup trace structures
686  * @q:    the request queue associated with the device
687  *
688  **/
689 void blk_trace_shutdown(struct request_queue *q)
690 {
691         if (q->blk_trace) {
692                 blk_trace_startstop(q, 0);
693                 blk_trace_remove(q);
694         }
695 }
696 
697 /*
698  * blktrace probes
699  */
700 
701 /**
702  * blk_add_trace_rq - Add a trace for a request oriented action
703  * @q:          queue the io is for
704  * @rq:         the source request
705  * @nr_bytes:   number of completed bytes
706  * @what:       the action
707  *
708  * Description:
709  *     Records an action against a request. Will log the bio offset + size.
710  *
711  **/
712 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
713                              unsigned int nr_bytes, u32 what)
714 {
715         struct blk_trace *bt = q->blk_trace;
716 
717         if (likely(!bt))
718                 return;
719 
720         if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
721                 what |= BLK_TC_ACT(BLK_TC_PC);
722                 __blk_add_trace(bt, 0, nr_bytes, rq->cmd_flags,
723                                 what, rq->errors, rq->cmd_len, rq->cmd);
724         } else  {
725                 what |= BLK_TC_ACT(BLK_TC_FS);
726                 __blk_add_trace(bt, blk_rq_pos(rq), nr_bytes,
727                                 rq->cmd_flags, what, rq->errors, 0, NULL);
728         }
729 }
730 
731 static void blk_add_trace_rq_abort(void *ignore,
732                                    struct request_queue *q, struct request *rq)
733 {
734         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_ABORT);
735 }
736 
737 static void blk_add_trace_rq_insert(void *ignore,
738                                     struct request_queue *q, struct request *rq)
739 {
740         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_INSERT);
741 }
742 
743 static void blk_add_trace_rq_issue(void *ignore,
744                                    struct request_queue *q, struct request *rq)
745 {
746         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_ISSUE);
747 }
748 
749 static void blk_add_trace_rq_requeue(void *ignore,
750                                      struct request_queue *q,
751                                      struct request *rq)
752 {
753         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_REQUEUE);
754 }
755 
756 static void blk_add_trace_rq_complete(void *ignore,
757                                       struct request_queue *q,
758                                       struct request *rq,
759                                       unsigned int nr_bytes)
760 {
761         blk_add_trace_rq(q, rq, nr_bytes, BLK_TA_COMPLETE);
762 }
763 
764 /**
765  * blk_add_trace_bio - Add a trace for a bio oriented action
766  * @q:          queue the io is for
767  * @bio:        the source bio
768  * @what:       the action
769  * @error:      error, if any
770  *
771  * Description:
772  *     Records an action against a bio. Will log the bio offset + size.
773  *
774  **/
775 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
776                               u32 what, int error)
777 {
778         struct blk_trace *bt = q->blk_trace;
779 
780         if (likely(!bt))
781                 return;
782 
783         if (!error && !bio_flagged(bio, BIO_UPTODATE))
784                 error = EIO;
785 
786         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
787                         bio->bi_rw, what, error, 0, NULL);
788 }
789 
790 static void blk_add_trace_bio_bounce(void *ignore,
791                                      struct request_queue *q, struct bio *bio)
792 {
793         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
794 }
795 
796 static void blk_add_trace_bio_complete(void *ignore,
797                                        struct request_queue *q, struct bio *bio,
798                                        int error)
799 {
800         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
801 }
802 
803 static void blk_add_trace_bio_backmerge(void *ignore,
804                                         struct request_queue *q,
805                                         struct request *rq,
806                                         struct bio *bio)
807 {
808         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
809 }
810 
811 static void blk_add_trace_bio_frontmerge(void *ignore,
812                                          struct request_queue *q,
813                                          struct request *rq,
814                                          struct bio *bio)
815 {
816         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
817 }
818 
819 static void blk_add_trace_bio_queue(void *ignore,
820                                     struct request_queue *q, struct bio *bio)
821 {
822         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
823 }
824 
825 static void blk_add_trace_getrq(void *ignore,
826                                 struct request_queue *q,
827                                 struct bio *bio, int rw)
828 {
829         if (bio)
830                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
831         else {
832                 struct blk_trace *bt = q->blk_trace;
833 
834                 if (bt)
835                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
836         }
837 }
838 
839 
840 static void blk_add_trace_sleeprq(void *ignore,
841                                   struct request_queue *q,
842                                   struct bio *bio, int rw)
843 {
844         if (bio)
845                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
846         else {
847                 struct blk_trace *bt = q->blk_trace;
848 
849                 if (bt)
850                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
851                                         0, 0, NULL);
852         }
853 }
854 
855 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
856 {
857         struct blk_trace *bt = q->blk_trace;
858 
859         if (bt)
860                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
861 }
862 
863 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
864                                     unsigned int depth, bool explicit)
865 {
866         struct blk_trace *bt = q->blk_trace;
867 
868         if (bt) {
869                 __be64 rpdu = cpu_to_be64(depth);
870                 u32 what;
871 
872                 if (explicit)
873                         what = BLK_TA_UNPLUG_IO;
874                 else
875                         what = BLK_TA_UNPLUG_TIMER;
876 
877                 __blk_add_trace(bt, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu);
878         }
879 }
880 
881 static void blk_add_trace_split(void *ignore,
882                                 struct request_queue *q, struct bio *bio,
883                                 unsigned int pdu)
884 {
885         struct blk_trace *bt = q->blk_trace;
886 
887         if (bt) {
888                 __be64 rpdu = cpu_to_be64(pdu);
889 
890                 __blk_add_trace(bt, bio->bi_iter.bi_sector,
891                                 bio->bi_iter.bi_size, bio->bi_rw, BLK_TA_SPLIT,
892                                 !bio_flagged(bio, BIO_UPTODATE),
893                                 sizeof(rpdu), &rpdu);
894         }
895 }
896 
897 /**
898  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
899  * @ignore:     trace callback data parameter (not used)
900  * @q:          queue the io is for
901  * @bio:        the source bio
902  * @dev:        target device
903  * @from:       source sector
904  *
905  * Description:
906  *     Device mapper or raid target sometimes need to split a bio because
907  *     it spans a stripe (or similar). Add a trace for that action.
908  *
909  **/
910 static void blk_add_trace_bio_remap(void *ignore,
911                                     struct request_queue *q, struct bio *bio,
912                                     dev_t dev, sector_t from)
913 {
914         struct blk_trace *bt = q->blk_trace;
915         struct blk_io_trace_remap r;
916 
917         if (likely(!bt))
918                 return;
919 
920         r.device_from = cpu_to_be32(dev);
921         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
922         r.sector_from = cpu_to_be64(from);
923 
924         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
925                         bio->bi_rw, BLK_TA_REMAP,
926                         !bio_flagged(bio, BIO_UPTODATE), sizeof(r), &r);
927 }
928 
929 /**
930  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
931  * @ignore:     trace callback data parameter (not used)
932  * @q:          queue the io is for
933  * @rq:         the source request
934  * @dev:        target device
935  * @from:       source sector
936  *
937  * Description:
938  *     Device mapper remaps request to other devices.
939  *     Add a trace for that action.
940  *
941  **/
942 static void blk_add_trace_rq_remap(void *ignore,
943                                    struct request_queue *q,
944                                    struct request *rq, dev_t dev,
945                                    sector_t from)
946 {
947         struct blk_trace *bt = q->blk_trace;
948         struct blk_io_trace_remap r;
949 
950         if (likely(!bt))
951                 return;
952 
953         r.device_from = cpu_to_be32(dev);
954         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
955         r.sector_from = cpu_to_be64(from);
956 
957         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
958                         rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
959                         sizeof(r), &r);
960 }
961 
962 /**
963  * blk_add_driver_data - Add binary message with driver-specific data
964  * @q:          queue the io is for
965  * @rq:         io request
966  * @data:       driver-specific data
967  * @len:        length of driver-specific data
968  *
969  * Description:
970  *     Some drivers might want to write driver-specific data per request.
971  *
972  **/
973 void blk_add_driver_data(struct request_queue *q,
974                          struct request *rq,
975                          void *data, size_t len)
976 {
977         struct blk_trace *bt = q->blk_trace;
978 
979         if (likely(!bt))
980                 return;
981 
982         if (rq->cmd_type == REQ_TYPE_BLOCK_PC)
983                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
984                                 BLK_TA_DRV_DATA, rq->errors, len, data);
985         else
986                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
987                                 BLK_TA_DRV_DATA, rq->errors, len, data);
988 }
989 EXPORT_SYMBOL_GPL(blk_add_driver_data);
990 
991 static void blk_register_tracepoints(void)
992 {
993         int ret;
994 
995         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
996         WARN_ON(ret);
997         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
998         WARN_ON(ret);
999         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1000         WARN_ON(ret);
1001         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1002         WARN_ON(ret);
1003         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1004         WARN_ON(ret);
1005         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1006         WARN_ON(ret);
1007         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1008         WARN_ON(ret);
1009         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1010         WARN_ON(ret);
1011         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1012         WARN_ON(ret);
1013         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1014         WARN_ON(ret);
1015         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1016         WARN_ON(ret);
1017         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1018         WARN_ON(ret);
1019         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1020         WARN_ON(ret);
1021         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1022         WARN_ON(ret);
1023         ret = register_trace_block_split(blk_add_trace_split, NULL);
1024         WARN_ON(ret);
1025         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1026         WARN_ON(ret);
1027         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1028         WARN_ON(ret);
1029 }
1030 
1031 static void blk_unregister_tracepoints(void)
1032 {
1033         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1034         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1035         unregister_trace_block_split(blk_add_trace_split, NULL);
1036         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1037         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1038         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1039         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1040         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1041         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1042         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1043         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1044         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1045         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1046         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1047         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1048         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1049         unregister_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
1050 
1051         tracepoint_synchronize_unregister();
1052 }
1053 
1054 /*
1055  * struct blk_io_tracer formatting routines
1056  */
1057 
1058 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1059 {
1060         int i = 0;
1061         int tc = t->action >> BLK_TC_SHIFT;
1062 
1063         if (t->action == BLK_TN_MESSAGE) {
1064                 rwbs[i++] = 'N';
1065                 goto out;
1066         }
1067 
1068         if (tc & BLK_TC_FLUSH)
1069                 rwbs[i++] = 'F';
1070 
1071         if (tc & BLK_TC_DISCARD)
1072                 rwbs[i++] = 'D';
1073         else if (tc & BLK_TC_WRITE)
1074                 rwbs[i++] = 'W';
1075         else if (t->bytes)
1076                 rwbs[i++] = 'R';
1077         else
1078                 rwbs[i++] = 'N';
1079 
1080         if (tc & BLK_TC_FUA)
1081                 rwbs[i++] = 'F';
1082         if (tc & BLK_TC_AHEAD)
1083                 rwbs[i++] = 'A';
1084         if (tc & BLK_TC_SYNC)
1085                 rwbs[i++] = 'S';
1086         if (tc & BLK_TC_META)
1087                 rwbs[i++] = 'M';
1088 out:
1089         rwbs[i] = '\0';
1090 }
1091 
1092 static inline
1093 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1094 {
1095         return (const struct blk_io_trace *)ent;
1096 }
1097 
1098 static inline const void *pdu_start(const struct trace_entry *ent)
1099 {
1100         return te_blk_io_trace(ent) + 1;
1101 }
1102 
1103 static inline u32 t_action(const struct trace_entry *ent)
1104 {
1105         return te_blk_io_trace(ent)->action;
1106 }
1107 
1108 static inline u32 t_bytes(const struct trace_entry *ent)
1109 {
1110         return te_blk_io_trace(ent)->bytes;
1111 }
1112 
1113 static inline u32 t_sec(const struct trace_entry *ent)
1114 {
1115         return te_blk_io_trace(ent)->bytes >> 9;
1116 }
1117 
1118 static inline unsigned long long t_sector(const struct trace_entry *ent)
1119 {
1120         return te_blk_io_trace(ent)->sector;
1121 }
1122 
1123 static inline __u16 t_error(const struct trace_entry *ent)
1124 {
1125         return te_blk_io_trace(ent)->error;
1126 }
1127 
1128 static __u64 get_pdu_int(const struct trace_entry *ent)
1129 {
1130         const __u64 *val = pdu_start(ent);
1131         return be64_to_cpu(*val);
1132 }
1133 
1134 static void get_pdu_remap(const struct trace_entry *ent,
1135                           struct blk_io_trace_remap *r)
1136 {
1137         const struct blk_io_trace_remap *__r = pdu_start(ent);
1138         __u64 sector_from = __r->sector_from;
1139 
1140         r->device_from = be32_to_cpu(__r->device_from);
1141         r->device_to   = be32_to_cpu(__r->device_to);
1142         r->sector_from = be64_to_cpu(sector_from);
1143 }
1144 
1145 typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1146 
1147 static void blk_log_action_classic(struct trace_iterator *iter, const char *act)
1148 {
1149         char rwbs[RWBS_LEN];
1150         unsigned long long ts  = iter->ts;
1151         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1152         unsigned secs          = (unsigned long)ts;
1153         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1154 
1155         fill_rwbs(rwbs, t);
1156 
1157         trace_seq_printf(&iter->seq,
1158                          "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1159                          MAJOR(t->device), MINOR(t->device), iter->cpu,
1160                          secs, nsec_rem, iter->ent->pid, act, rwbs);
1161 }
1162 
1163 static void blk_log_action(struct trace_iterator *iter, const char *act)
1164 {
1165         char rwbs[RWBS_LEN];
1166         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1167 
1168         fill_rwbs(rwbs, t);
1169         trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1170                          MAJOR(t->device), MINOR(t->device), act, rwbs);
1171 }
1172 
1173 static void blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1174 {
1175         const unsigned char *pdu_buf;
1176         int pdu_len;
1177         int i, end;
1178 
1179         pdu_buf = pdu_start(ent);
1180         pdu_len = te_blk_io_trace(ent)->pdu_len;
1181 
1182         if (!pdu_len)
1183                 return;
1184 
1185         /* find the last zero that needs to be printed */
1186         for (end = pdu_len - 1; end >= 0; end--)
1187                 if (pdu_buf[end])
1188                         break;
1189         end++;
1190 
1191         trace_seq_putc(s, '(');
1192 
1193         for (i = 0; i < pdu_len; i++) {
1194 
1195                 trace_seq_printf(s, "%s%02x",
1196                                  i == 0 ? "" : " ", pdu_buf[i]);
1197 
1198                 /*
1199                  * stop when the rest is just zeroes and indicate so
1200                  * with a ".." appended
1201                  */
1202                 if (i == end && end != pdu_len - 1) {
1203                         trace_seq_puts(s, " ..) ");
1204                         return;
1205                 }
1206         }
1207 
1208         trace_seq_puts(s, ") ");
1209 }
1210 
1211 static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1212 {
1213         char cmd[TASK_COMM_LEN];
1214 
1215         trace_find_cmdline(ent->pid, cmd);
1216 
1217         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1218                 trace_seq_printf(s, "%u ", t_bytes(ent));
1219                 blk_log_dump_pdu(s, ent);
1220                 trace_seq_printf(s, "[%s]\n", cmd);
1221         } else {
1222                 if (t_sec(ent))
1223                         trace_seq_printf(s, "%llu + %u [%s]\n",
1224                                                 t_sector(ent), t_sec(ent), cmd);
1225                 else
1226                         trace_seq_printf(s, "[%s]\n", cmd);
1227         }
1228 }
1229 
1230 static void blk_log_with_error(struct trace_seq *s,
1231                               const struct trace_entry *ent)
1232 {
1233         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1234                 blk_log_dump_pdu(s, ent);
1235                 trace_seq_printf(s, "[%d]\n", t_error(ent));
1236         } else {
1237                 if (t_sec(ent))
1238                         trace_seq_printf(s, "%llu + %u [%d]\n",
1239                                          t_sector(ent),
1240                                          t_sec(ent), t_error(ent));
1241                 else
1242                         trace_seq_printf(s, "%llu [%d]\n",
1243                                          t_sector(ent), t_error(ent));
1244         }
1245 }
1246 
1247 static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1248 {
1249         struct blk_io_trace_remap r = { .device_from = 0, };
1250 
1251         get_pdu_remap(ent, &r);
1252         trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1253                          t_sector(ent), t_sec(ent),
1254                          MAJOR(r.device_from), MINOR(r.device_from),
1255                          (unsigned long long)r.sector_from);
1256 }
1257 
1258 static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1259 {
1260         char cmd[TASK_COMM_LEN];
1261 
1262         trace_find_cmdline(ent->pid, cmd);
1263 
1264         trace_seq_printf(s, "[%s]\n", cmd);
1265 }
1266 
1267 static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1268 {
1269         char cmd[TASK_COMM_LEN];
1270 
1271         trace_find_cmdline(ent->pid, cmd);
1272 
1273         trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1274 }
1275 
1276 static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1277 {
1278         char cmd[TASK_COMM_LEN];
1279 
1280         trace_find_cmdline(ent->pid, cmd);
1281 
1282         trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1283                          get_pdu_int(ent), cmd);
1284 }
1285 
1286 static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1287 {
1288         const struct blk_io_trace *t = te_blk_io_trace(ent);
1289 
1290         trace_seq_putmem(s, t + 1, t->pdu_len);
1291         trace_seq_putc(s, '\n');
1292 }
1293 
1294 /*
1295  * struct tracer operations
1296  */
1297 
1298 static void blk_tracer_print_header(struct seq_file *m)
1299 {
1300         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1301                 return;
1302         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1303                     "#  |     |     |           |   |   |\n");
1304 }
1305 
1306 static void blk_tracer_start(struct trace_array *tr)
1307 {
1308         blk_tracer_enabled = true;
1309 }
1310 
1311 static int blk_tracer_init(struct trace_array *tr)
1312 {
1313         blk_tr = tr;
1314         blk_tracer_start(tr);
1315         return 0;
1316 }
1317 
1318 static void blk_tracer_stop(struct trace_array *tr)
1319 {
1320         blk_tracer_enabled = false;
1321 }
1322 
1323 static void blk_tracer_reset(struct trace_array *tr)
1324 {
1325         blk_tracer_stop(tr);
1326 }
1327 
1328 static const struct {
1329         const char *act[2];
1330         void       (*print)(struct trace_seq *s, const struct trace_entry *ent);
1331 } what2act[] = {
1332         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1333         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1334         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1335         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1336         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1337         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1338         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1339         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1340         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1341         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1342         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1343         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1344         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1345         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1346         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1347 };
1348 
1349 static enum print_line_t print_one_line(struct trace_iterator *iter,
1350                                         bool classic)
1351 {
1352         struct trace_seq *s = &iter->seq;
1353         const struct blk_io_trace *t;
1354         u16 what;
1355         bool long_act;
1356         blk_log_action_t *log_action;
1357 
1358         t          = te_blk_io_trace(iter->ent);
1359         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1360         long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1361         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1362 
1363         if (t->action == BLK_TN_MESSAGE) {
1364                 log_action(iter, long_act ? "message" : "m");
1365                 blk_log_msg(s, iter->ent);
1366         }
1367 
1368         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1369                 trace_seq_printf(s, "Unknown action %x\n", what);
1370         else {
1371                 log_action(iter, what2act[what].act[long_act]);
1372                 what2act[what].print(s, iter->ent);
1373         }
1374 
1375         return trace_handle_return(s);
1376 }
1377 
1378 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1379                                                int flags, struct trace_event *event)
1380 {
1381         return print_one_line(iter, false);
1382 }
1383 
1384 static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1385 {
1386         struct trace_seq *s = &iter->seq;
1387         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1388         const int offset = offsetof(struct blk_io_trace, sector);
1389         struct blk_io_trace old = {
1390                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1391                 .time     = iter->ts,
1392         };
1393 
1394         trace_seq_putmem(s, &old, offset);
1395         trace_seq_putmem(s, &t->sector,
1396                          sizeof(old) - offset + t->pdu_len);
1397 }
1398 
1399 static enum print_line_t
1400 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1401                              struct trace_event *event)
1402 {
1403         blk_trace_synthesize_old_trace(iter);
1404 
1405         return trace_handle_return(&iter->seq);
1406 }
1407 
1408 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1409 {
1410         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1411                 return TRACE_TYPE_UNHANDLED;
1412 
1413         return print_one_line(iter, true);
1414 }
1415 
1416 static int
1417 blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1418 {
1419         /* don't output context-info for blk_classic output */
1420         if (bit == TRACE_BLK_OPT_CLASSIC) {
1421                 if (set)
1422                         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1423                 else
1424                         trace_flags |= TRACE_ITER_CONTEXT_INFO;
1425         }
1426         return 0;
1427 }
1428 
1429 static struct tracer blk_tracer __read_mostly = {
1430         .name           = "blk",
1431         .init           = blk_tracer_init,
1432         .reset          = blk_tracer_reset,
1433         .start          = blk_tracer_start,
1434         .stop           = blk_tracer_stop,
1435         .print_header   = blk_tracer_print_header,
1436         .print_line     = blk_tracer_print_line,
1437         .flags          = &blk_tracer_flags,
1438         .set_flag       = blk_tracer_set_flag,
1439 };
1440 
1441 static struct trace_event_functions trace_blk_event_funcs = {
1442         .trace          = blk_trace_event_print,
1443         .binary         = blk_trace_event_print_binary,
1444 };
1445 
1446 static struct trace_event trace_blk_event = {
1447         .type           = TRACE_BLK,
1448         .funcs          = &trace_blk_event_funcs,
1449 };
1450 
1451 static int __init init_blk_tracer(void)
1452 {
1453         if (!register_ftrace_event(&trace_blk_event)) {
1454                 pr_warning("Warning: could not register block events\n");
1455                 return 1;
1456         }
1457 
1458         if (register_tracer(&blk_tracer) != 0) {
1459                 pr_warning("Warning: could not register the block tracer\n");
1460                 unregister_ftrace_event(&trace_blk_event);
1461                 return 1;
1462         }
1463 
1464         return 0;
1465 }
1466 
1467 device_initcall(init_blk_tracer);
1468 
1469 static int blk_trace_remove_queue(struct request_queue *q)
1470 {
1471         struct blk_trace *bt;
1472 
1473         bt = xchg(&q->blk_trace, NULL);
1474         if (bt == NULL)
1475                 return -EINVAL;
1476 
1477         if (atomic_dec_and_test(&blk_probes_ref))
1478                 blk_unregister_tracepoints();
1479 
1480         blk_trace_free(bt);
1481         return 0;
1482 }
1483 
1484 /*
1485  * Setup everything required to start tracing
1486  */
1487 static int blk_trace_setup_queue(struct request_queue *q,
1488                                  struct block_device *bdev)
1489 {
1490         struct blk_trace *old_bt, *bt = NULL;
1491         int ret = -ENOMEM;
1492 
1493         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1494         if (!bt)
1495                 return -ENOMEM;
1496 
1497         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1498         if (!bt->msg_data)
1499                 goto free_bt;
1500 
1501         bt->dev = bdev->bd_dev;
1502         bt->act_mask = (u16)-1;
1503 
1504         blk_trace_setup_lba(bt, bdev);
1505 
1506         old_bt = xchg(&q->blk_trace, bt);
1507         if (old_bt != NULL) {
1508                 (void)xchg(&q->blk_trace, old_bt);
1509                 ret = -EBUSY;
1510                 goto free_bt;
1511         }
1512 
1513         if (atomic_inc_return(&blk_probes_ref) == 1)
1514                 blk_register_tracepoints();
1515         return 0;
1516 
1517 free_bt:
1518         blk_trace_free(bt);
1519         return ret;
1520 }
1521 
1522 /*
1523  * sysfs interface to enable and configure tracing
1524  */
1525 
1526 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1527                                          struct device_attribute *attr,
1528                                          char *buf);
1529 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1530                                           struct device_attribute *attr,
1531                                           const char *buf, size_t count);
1532 #define BLK_TRACE_DEVICE_ATTR(_name) \
1533         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1534                     sysfs_blk_trace_attr_show, \
1535                     sysfs_blk_trace_attr_store)
1536 
1537 static BLK_TRACE_DEVICE_ATTR(enable);
1538 static BLK_TRACE_DEVICE_ATTR(act_mask);
1539 static BLK_TRACE_DEVICE_ATTR(pid);
1540 static BLK_TRACE_DEVICE_ATTR(start_lba);
1541 static BLK_TRACE_DEVICE_ATTR(end_lba);
1542 
1543 static struct attribute *blk_trace_attrs[] = {
1544         &dev_attr_enable.attr,
1545         &dev_attr_act_mask.attr,
1546         &dev_attr_pid.attr,
1547         &dev_attr_start_lba.attr,
1548         &dev_attr_end_lba.attr,
1549         NULL
1550 };
1551 
1552 struct attribute_group blk_trace_attr_group = {
1553         .name  = "trace",
1554         .attrs = blk_trace_attrs,
1555 };
1556 
1557 static const struct {
1558         int mask;
1559         const char *str;
1560 } mask_maps[] = {
1561         { BLK_TC_READ,          "read"          },
1562         { BLK_TC_WRITE,         "write"         },
1563         { BLK_TC_FLUSH,         "flush"         },
1564         { BLK_TC_SYNC,          "sync"          },
1565         { BLK_TC_QUEUE,         "queue"         },
1566         { BLK_TC_REQUEUE,       "requeue"       },
1567         { BLK_TC_ISSUE,         "issue"         },
1568         { BLK_TC_COMPLETE,      "complete"      },
1569         { BLK_TC_FS,            "fs"            },
1570         { BLK_TC_PC,            "pc"            },
1571         { BLK_TC_AHEAD,         "ahead"         },
1572         { BLK_TC_META,          "meta"          },
1573         { BLK_TC_DISCARD,       "discard"       },
1574         { BLK_TC_DRV_DATA,      "drv_data"      },
1575         { BLK_TC_FUA,           "fua"           },
1576 };
1577 
1578 static int blk_trace_str2mask(const char *str)
1579 {
1580         int i;
1581         int mask = 0;
1582         char *buf, *s, *token;
1583 
1584         buf = kstrdup(str, GFP_KERNEL);
1585         if (buf == NULL)
1586                 return -ENOMEM;
1587         s = strstrip(buf);
1588 
1589         while (1) {
1590                 token = strsep(&s, ",");
1591                 if (token == NULL)
1592                         break;
1593 
1594                 if (*token == '\0')
1595                         continue;
1596 
1597                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1598                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1599                                 mask |= mask_maps[i].mask;
1600                                 break;
1601                         }
1602                 }
1603                 if (i == ARRAY_SIZE(mask_maps)) {
1604                         mask = -EINVAL;
1605                         break;
1606                 }
1607         }
1608         kfree(buf);
1609 
1610         return mask;
1611 }
1612 
1613 static ssize_t blk_trace_mask2str(char *buf, int mask)
1614 {
1615         int i;
1616         char *p = buf;
1617 
1618         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1619                 if (mask & mask_maps[i].mask) {
1620                         p += sprintf(p, "%s%s",
1621                                     (p == buf) ? "" : ",", mask_maps[i].str);
1622                 }
1623         }
1624         *p++ = '\n';
1625 
1626         return p - buf;
1627 }
1628 
1629 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1630 {
1631         if (bdev->bd_disk == NULL)
1632                 return NULL;
1633 
1634         return bdev_get_queue(bdev);
1635 }
1636 
1637 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1638                                          struct device_attribute *attr,
1639                                          char *buf)
1640 {
1641         struct hd_struct *p = dev_to_part(dev);
1642         struct request_queue *q;
1643         struct block_device *bdev;
1644         ssize_t ret = -ENXIO;
1645 
1646         bdev = bdget(part_devt(p));
1647         if (bdev == NULL)
1648                 goto out;
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                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1658                 goto out_unlock_bdev;
1659         }
1660 
1661         if (q->blk_trace == NULL)
1662                 ret = sprintf(buf, "disabled\n");
1663         else if (attr == &dev_attr_act_mask)
1664                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1665         else if (attr == &dev_attr_pid)
1666                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1667         else if (attr == &dev_attr_start_lba)
1668                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1669         else if (attr == &dev_attr_end_lba)
1670                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1671 
1672 out_unlock_bdev:
1673         mutex_unlock(&bdev->bd_mutex);
1674 out_bdput:
1675         bdput(bdev);
1676 out:
1677         return ret;
1678 }
1679 
1680 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1681                                           struct device_attribute *attr,
1682                                           const char *buf, size_t count)
1683 {
1684         struct block_device *bdev;
1685         struct request_queue *q;
1686         struct hd_struct *p;
1687         u64 value;
1688         ssize_t ret = -EINVAL;
1689 
1690         if (count == 0)
1691                 goto out;
1692 
1693         if (attr == &dev_attr_act_mask) {
1694                 if (sscanf(buf, "%llx", &value) != 1) {
1695                         /* Assume it is a list of trace category names */
1696                         ret = blk_trace_str2mask(buf);
1697                         if (ret < 0)
1698                                 goto out;
1699                         value = ret;
1700                 }
1701         } else if (sscanf(buf, "%llu", &value) != 1)
1702                 goto out;
1703 
1704         ret = -ENXIO;
1705 
1706         p = dev_to_part(dev);
1707         bdev = bdget(part_devt(p));
1708         if (bdev == NULL)
1709                 goto out;
1710 
1711         q = blk_trace_get_queue(bdev);
1712         if (q == NULL)
1713                 goto out_bdput;
1714 
1715         mutex_lock(&bdev->bd_mutex);
1716 
1717         if (attr == &dev_attr_enable) {
1718                 if (value)
1719                         ret = blk_trace_setup_queue(q, bdev);
1720                 else
1721                         ret = blk_trace_remove_queue(q);
1722                 goto out_unlock_bdev;
1723         }
1724 
1725         ret = 0;
1726         if (q->blk_trace == NULL)
1727                 ret = blk_trace_setup_queue(q, bdev);
1728 
1729         if (ret == 0) {
1730                 if (attr == &dev_attr_act_mask)
1731                         q->blk_trace->act_mask = value;
1732                 else if (attr == &dev_attr_pid)
1733                         q->blk_trace->pid = value;
1734                 else if (attr == &dev_attr_start_lba)
1735                         q->blk_trace->start_lba = value;
1736                 else if (attr == &dev_attr_end_lba)
1737                         q->blk_trace->end_lba = value;
1738         }
1739 
1740 out_unlock_bdev:
1741         mutex_unlock(&bdev->bd_mutex);
1742 out_bdput:
1743         bdput(bdev);
1744 out:
1745         return ret ? ret : count;
1746 }
1747 
1748 int blk_trace_init_sysfs(struct device *dev)
1749 {
1750         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1751 }
1752 
1753 void blk_trace_remove_sysfs(struct device *dev)
1754 {
1755         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1756 }
1757 
1758 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1759 
1760 #ifdef CONFIG_EVENT_TRACING
1761 
1762 void blk_dump_cmd(char *buf, struct request *rq)
1763 {
1764         int i, end;
1765         int len = rq->cmd_len;
1766         unsigned char *cmd = rq->cmd;
1767 
1768         if (rq->cmd_type != REQ_TYPE_BLOCK_PC) {
1769                 buf[0] = '\0';
1770                 return;
1771         }
1772 
1773         for (end = len - 1; end >= 0; end--)
1774                 if (cmd[end])
1775                         break;
1776         end++;
1777 
1778         for (i = 0; i < len; i++) {
1779                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1780                 if (i == end && end != len - 1) {
1781                         sprintf(buf, " ..");
1782                         break;
1783                 }
1784         }
1785 }
1786 
1787 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1788 {
1789         int i = 0;
1790 
1791         if (rw & REQ_FLUSH)
1792                 rwbs[i++] = 'F';
1793 
1794         if (rw & WRITE)
1795                 rwbs[i++] = 'W';
1796         else if (rw & REQ_DISCARD)
1797                 rwbs[i++] = 'D';
1798         else if (bytes)
1799                 rwbs[i++] = 'R';
1800         else
1801                 rwbs[i++] = 'N';
1802 
1803         if (rw & REQ_FUA)
1804                 rwbs[i++] = 'F';
1805         if (rw & REQ_RAHEAD)
1806                 rwbs[i++] = 'A';
1807         if (rw & REQ_SYNC)
1808                 rwbs[i++] = 'S';
1809         if (rw & REQ_META)
1810                 rwbs[i++] = 'M';
1811         if (rw & REQ_SECURE)
1812                 rwbs[i++] = 'E';
1813 
1814         rwbs[i] = '\0';
1815 }
1816 EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1817 
1818 #endif /* CONFIG_EVENT_TRACING */
1819 
1820 

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