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

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
  4  *
  5  */
  6 
  7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  8 
  9 #include <linux/kernel.h>
 10 #include <linux/blkdev.h>
 11 #include <linux/blktrace_api.h>
 12 #include <linux/percpu.h>
 13 #include <linux/init.h>
 14 #include <linux/mutex.h>
 15 #include <linux/slab.h>
 16 #include <linux/debugfs.h>
 17 #include <linux/export.h>
 18 #include <linux/time.h>
 19 #include <linux/uaccess.h>
 20 #include <linux/list.h>
 21 #include <linux/blk-cgroup.h>
 22 
 23 #include "../../block/blk.h"
 24 
 25 #include <trace/events/block.h>
 26 
 27 #include "trace_output.h"
 28 
 29 #ifdef CONFIG_BLK_DEV_IO_TRACE
 30 
 31 static unsigned int blktrace_seq __read_mostly = 1;
 32 
 33 static struct trace_array *blk_tr;
 34 static bool blk_tracer_enabled __read_mostly;
 35 
 36 static LIST_HEAD(running_trace_list);
 37 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock);
 38 
 39 /* Select an alternative, minimalistic output than the original one */
 40 #define TRACE_BLK_OPT_CLASSIC   0x1
 41 #define TRACE_BLK_OPT_CGROUP    0x2
 42 #define TRACE_BLK_OPT_CGNAME    0x4
 43 
 44 static struct tracer_opt blk_tracer_opts[] = {
 45         /* Default disable the minimalistic output */
 46         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
 47 #ifdef CONFIG_BLK_CGROUP
 48         { TRACER_OPT(blk_cgroup, TRACE_BLK_OPT_CGROUP) },
 49         { TRACER_OPT(blk_cgname, TRACE_BLK_OPT_CGNAME) },
 50 #endif
 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 DEFINE_MUTEX(blk_probe_mutex);
 61 static int blk_probes_ref;
 62 
 63 static void blk_register_tracepoints(void);
 64 static void blk_unregister_tracepoints(void);
 65 
 66 /*
 67  * Send out a notify message.
 68  */
 69 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 70                        const void *data, size_t len, u64 cgid)
 71 {
 72         struct blk_io_trace *t;
 73         struct ring_buffer_event *event = NULL;
 74         struct trace_buffer *buffer = NULL;
 75         unsigned int trace_ctx = 0;
 76         int cpu = smp_processor_id();
 77         bool blk_tracer = blk_tracer_enabled;
 78         ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
 79 
 80         if (blk_tracer) {
 81                 buffer = blk_tr->array_buffer.buffer;
 82                 trace_ctx = tracing_gen_ctx_flags(0);
 83                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 84                                                   sizeof(*t) + len + cgid_len,
 85                                                   trace_ctx);
 86                 if (!event)
 87                         return;
 88                 t = ring_buffer_event_data(event);
 89                 goto record_it;
 90         }
 91 
 92         if (!bt->rchan)
 93                 return;
 94 
 95         t = relay_reserve(bt->rchan, sizeof(*t) + len + cgid_len);
 96         if (t) {
 97                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 98                 t->time = ktime_to_ns(ktime_get());
 99 record_it:
100                 t->device = bt->dev;
101                 t->action = action | (cgid ? __BLK_TN_CGROUP : 0);
102                 t->pid = pid;
103                 t->cpu = cpu;
104                 t->pdu_len = len + cgid_len;
105                 if (cgid_len)
106                         memcpy((void *)t + sizeof(*t), &cgid, cgid_len);
107                 memcpy((void *) t + sizeof(*t) + cgid_len, data, len);
108 
109                 if (blk_tracer)
110                         trace_buffer_unlock_commit(blk_tr, buffer, event, trace_ctx);
111         }
112 }
113 
114 /*
115  * Send out a notify for this process, if we haven't done so since a trace
116  * started
117  */
118 static void trace_note_tsk(struct task_struct *tsk)
119 {
120         unsigned long flags;
121         struct blk_trace *bt;
122 
123         tsk->btrace_seq = blktrace_seq;
124         spin_lock_irqsave(&running_trace_lock, flags);
125         list_for_each_entry(bt, &running_trace_list, running_list) {
126                 trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm,
127                            sizeof(tsk->comm), 0);
128         }
129         spin_unlock_irqrestore(&running_trace_lock, flags);
130 }
131 
132 static void trace_note_time(struct blk_trace *bt)
133 {
134         struct timespec64 now;
135         unsigned long flags;
136         u32 words[2];
137 
138         /* need to check user space to see if this breaks in y2038 or y2106 */
139         ktime_get_real_ts64(&now);
140         words[0] = (u32)now.tv_sec;
141         words[1] = now.tv_nsec;
142 
143         local_irq_save(flags);
144         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words), 0);
145         local_irq_restore(flags);
146 }
147 
148 void __trace_note_message(struct blk_trace *bt, struct blkcg *blkcg,
149         const char *fmt, ...)
150 {
151         int n;
152         va_list args;
153         unsigned long flags;
154         char *buf;
155 
156         if (unlikely(bt->trace_state != Blktrace_running &&
157                      !blk_tracer_enabled))
158                 return;
159 
160         /*
161          * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
162          * message to the trace.
163          */
164         if (!(bt->act_mask & BLK_TC_NOTIFY))
165                 return;
166 
167         local_irq_save(flags);
168         buf = this_cpu_ptr(bt->msg_data);
169         va_start(args, fmt);
170         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
171         va_end(args);
172 
173         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
174                 blkcg = NULL;
175 #ifdef CONFIG_BLK_CGROUP
176         trace_note(bt, current->pid, BLK_TN_MESSAGE, buf, n,
177                    blkcg ? cgroup_id(blkcg->css.cgroup) : 1);
178 #else
179         trace_note(bt, current->pid, BLK_TN_MESSAGE, buf, n, 0);
180 #endif
181         local_irq_restore(flags);
182 }
183 EXPORT_SYMBOL_GPL(__trace_note_message);
184 
185 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
186                          pid_t pid)
187 {
188         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
189                 return 1;
190         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
191                 return 1;
192         if (bt->pid && pid != bt->pid)
193                 return 1;
194 
195         return 0;
196 }
197 
198 /*
199  * Data direction bit lookup
200  */
201 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
202                                  BLK_TC_ACT(BLK_TC_WRITE) };
203 
204 #define BLK_TC_RAHEAD           BLK_TC_AHEAD
205 #define BLK_TC_PREFLUSH         BLK_TC_FLUSH
206 
207 /* The ilog2() calls fall out because they're constant */
208 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
209           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
210 
211 /*
212  * The worker for the various blk_add_trace*() types. Fills out a
213  * blk_io_trace structure and places it in a per-cpu subbuffer.
214  */
215 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
216                      int op, int op_flags, u32 what, int error, int pdu_len,
217                      void *pdu_data, u64 cgid)
218 {
219         struct task_struct *tsk = current;
220         struct ring_buffer_event *event = NULL;
221         struct trace_buffer *buffer = NULL;
222         struct blk_io_trace *t;
223         unsigned long flags = 0;
224         unsigned long *sequence;
225         unsigned int trace_ctx = 0;
226         pid_t pid;
227         int cpu;
228         bool blk_tracer = blk_tracer_enabled;
229         ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
230 
231         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
232                 return;
233 
234         what |= ddir_act[op_is_write(op) ? WRITE : READ];
235         what |= MASK_TC_BIT(op_flags, SYNC);
236         what |= MASK_TC_BIT(op_flags, RAHEAD);
237         what |= MASK_TC_BIT(op_flags, META);
238         what |= MASK_TC_BIT(op_flags, PREFLUSH);
239         what |= MASK_TC_BIT(op_flags, FUA);
240         if (op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE)
241                 what |= BLK_TC_ACT(BLK_TC_DISCARD);
242         if (op == REQ_OP_FLUSH)
243                 what |= BLK_TC_ACT(BLK_TC_FLUSH);
244         if (cgid)
245                 what |= __BLK_TA_CGROUP;
246 
247         pid = tsk->pid;
248         if (act_log_check(bt, what, sector, pid))
249                 return;
250         cpu = raw_smp_processor_id();
251 
252         if (blk_tracer) {
253                 tracing_record_cmdline(current);
254 
255                 buffer = blk_tr->array_buffer.buffer;
256                 trace_ctx = tracing_gen_ctx_flags(0);
257                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
258                                                   sizeof(*t) + pdu_len + cgid_len,
259                                                   trace_ctx);
260                 if (!event)
261                         return;
262                 t = ring_buffer_event_data(event);
263                 goto record_it;
264         }
265 
266         if (unlikely(tsk->btrace_seq != blktrace_seq))
267                 trace_note_tsk(tsk);
268 
269         /*
270          * A word about the locking here - we disable interrupts to reserve
271          * some space in the relay per-cpu buffer, to prevent an irq
272          * from coming in and stepping on our toes.
273          */
274         local_irq_save(flags);
275         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len + cgid_len);
276         if (t) {
277                 sequence = per_cpu_ptr(bt->sequence, cpu);
278 
279                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
280                 t->sequence = ++(*sequence);
281                 t->time = ktime_to_ns(ktime_get());
282 record_it:
283                 /*
284                  * These two are not needed in ftrace as they are in the
285                  * generic trace_entry, filled by tracing_generic_entry_update,
286                  * but for the trace_event->bin() synthesizer benefit we do it
287                  * here too.
288                  */
289                 t->cpu = cpu;
290                 t->pid = pid;
291 
292                 t->sector = sector;
293                 t->bytes = bytes;
294                 t->action = what;
295                 t->device = bt->dev;
296                 t->error = error;
297                 t->pdu_len = pdu_len + cgid_len;
298 
299                 if (cgid_len)
300                         memcpy((void *)t + sizeof(*t), &cgid, cgid_len);
301                 if (pdu_len)
302                         memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len);
303 
304                 if (blk_tracer) {
305                         trace_buffer_unlock_commit(blk_tr, buffer, event, trace_ctx);
306                         return;
307                 }
308         }
309 
310         local_irq_restore(flags);
311 }
312 
313 static void blk_trace_free(struct blk_trace *bt)
314 {
315         relay_close(bt->rchan);
316         debugfs_remove(bt->dir);
317         free_percpu(bt->sequence);
318         free_percpu(bt->msg_data);
319         kfree(bt);
320 }
321 
322 static void get_probe_ref(void)
323 {
324         mutex_lock(&blk_probe_mutex);
325         if (++blk_probes_ref == 1)
326                 blk_register_tracepoints();
327         mutex_unlock(&blk_probe_mutex);
328 }
329 
330 static void put_probe_ref(void)
331 {
332         mutex_lock(&blk_probe_mutex);
333         if (!--blk_probes_ref)
334                 blk_unregister_tracepoints();
335         mutex_unlock(&blk_probe_mutex);
336 }
337 
338 static void blk_trace_cleanup(struct blk_trace *bt)
339 {
340         synchronize_rcu();
341         blk_trace_free(bt);
342         put_probe_ref();
343 }
344 
345 static int __blk_trace_remove(struct request_queue *q)
346 {
347         struct blk_trace *bt;
348 
349         bt = rcu_replace_pointer(q->blk_trace, NULL,
350                                  lockdep_is_held(&q->debugfs_mutex));
351         if (!bt)
352                 return -EINVAL;
353 
354         if (bt->trace_state != Blktrace_running)
355                 blk_trace_cleanup(bt);
356 
357         return 0;
358 }
359 
360 int blk_trace_remove(struct request_queue *q)
361 {
362         int ret;
363 
364         mutex_lock(&q->debugfs_mutex);
365         ret = __blk_trace_remove(q);
366         mutex_unlock(&q->debugfs_mutex);
367 
368         return ret;
369 }
370 EXPORT_SYMBOL_GPL(blk_trace_remove);
371 
372 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
373                                 size_t count, loff_t *ppos)
374 {
375         struct blk_trace *bt = filp->private_data;
376         char buf[16];
377 
378         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
379 
380         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
381 }
382 
383 static const struct file_operations blk_dropped_fops = {
384         .owner =        THIS_MODULE,
385         .open =         simple_open,
386         .read =         blk_dropped_read,
387         .llseek =       default_llseek,
388 };
389 
390 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
391                                 size_t count, loff_t *ppos)
392 {
393         char *msg;
394         struct blk_trace *bt;
395 
396         if (count >= BLK_TN_MAX_MSG)
397                 return -EINVAL;
398 
399         msg = memdup_user_nul(buffer, count);
400         if (IS_ERR(msg))
401                 return PTR_ERR(msg);
402 
403         bt = filp->private_data;
404         __trace_note_message(bt, NULL, "%s", msg);
405         kfree(msg);
406 
407         return count;
408 }
409 
410 static const struct file_operations blk_msg_fops = {
411         .owner =        THIS_MODULE,
412         .open =         simple_open,
413         .write =        blk_msg_write,
414         .llseek =       noop_llseek,
415 };
416 
417 /*
418  * Keep track of how many times we encountered a full subbuffer, to aid
419  * the user space app in telling how many lost events there were.
420  */
421 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
422                                      void *prev_subbuf, size_t prev_padding)
423 {
424         struct blk_trace *bt;
425 
426         if (!relay_buf_full(buf))
427                 return 1;
428 
429         bt = buf->chan->private_data;
430         atomic_inc(&bt->dropped);
431         return 0;
432 }
433 
434 static int blk_remove_buf_file_callback(struct dentry *dentry)
435 {
436         debugfs_remove(dentry);
437 
438         return 0;
439 }
440 
441 static struct dentry *blk_create_buf_file_callback(const char *filename,
442                                                    struct dentry *parent,
443                                                    umode_t mode,
444                                                    struct rchan_buf *buf,
445                                                    int *is_global)
446 {
447         return debugfs_create_file(filename, mode, parent, buf,
448                                         &relay_file_operations);
449 }
450 
451 static const struct rchan_callbacks blk_relay_callbacks = {
452         .subbuf_start           = blk_subbuf_start_callback,
453         .create_buf_file        = blk_create_buf_file_callback,
454         .remove_buf_file        = blk_remove_buf_file_callback,
455 };
456 
457 static void blk_trace_setup_lba(struct blk_trace *bt,
458                                 struct block_device *bdev)
459 {
460         if (bdev) {
461                 bt->start_lba = bdev->bd_start_sect;
462                 bt->end_lba = bdev->bd_start_sect + bdev_nr_sectors(bdev);
463         } else {
464                 bt->start_lba = 0;
465                 bt->end_lba = -1ULL;
466         }
467 }
468 
469 /*
470  * Setup everything required to start tracing
471  */
472 static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
473                               struct block_device *bdev,
474                               struct blk_user_trace_setup *buts)
475 {
476         struct blk_trace *bt = NULL;
477         struct dentry *dir = NULL;
478         int ret;
479 
480         lockdep_assert_held(&q->debugfs_mutex);
481 
482         if (!buts->buf_size || !buts->buf_nr)
483                 return -EINVAL;
484 
485         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
486         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
487 
488         /*
489          * some device names have larger paths - convert the slashes
490          * to underscores for this to work as expected
491          */
492         strreplace(buts->name, '/', '_');
493 
494         /*
495          * bdev can be NULL, as with scsi-generic, this is a helpful as
496          * we can be.
497          */
498         if (rcu_dereference_protected(q->blk_trace,
499                                       lockdep_is_held(&q->debugfs_mutex))) {
500                 pr_warn("Concurrent blktraces are not allowed on %s\n",
501                         buts->name);
502                 return -EBUSY;
503         }
504 
505         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
506         if (!bt)
507                 return -ENOMEM;
508 
509         ret = -ENOMEM;
510         bt->sequence = alloc_percpu(unsigned long);
511         if (!bt->sequence)
512                 goto err;
513 
514         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
515         if (!bt->msg_data)
516                 goto err;
517 
518         /*
519          * When tracing the whole disk reuse the existing debugfs directory
520          * created by the block layer on init. For partitions block devices,
521          * and scsi-generic block devices we create a temporary new debugfs
522          * directory that will be removed once the trace ends.
523          */
524         if (bdev && !bdev_is_partition(bdev))
525                 dir = q->debugfs_dir;
526         else
527                 bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);
528 
529         /*
530          * As blktrace relies on debugfs for its interface the debugfs directory
531          * is required, contrary to the usual mantra of not checking for debugfs
532          * files or directories.
533          */
534         if (IS_ERR_OR_NULL(dir)) {
535                 pr_warn("debugfs_dir not present for %s so skipping\n",
536                         buts->name);
537                 ret = -ENOENT;
538                 goto err;
539         }
540 
541         bt->dev = dev;
542         atomic_set(&bt->dropped, 0);
543         INIT_LIST_HEAD(&bt->running_list);
544 
545         ret = -EIO;
546         debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops);
547         debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
548 
549         bt->rchan = relay_open("trace", dir, buts->buf_size,
550                                 buts->buf_nr, &blk_relay_callbacks, bt);
551         if (!bt->rchan)
552                 goto err;
553 
554         bt->act_mask = buts->act_mask;
555         if (!bt->act_mask)
556                 bt->act_mask = (u16) -1;
557 
558         blk_trace_setup_lba(bt, bdev);
559 
560         /* overwrite with user settings */
561         if (buts->start_lba)
562                 bt->start_lba = buts->start_lba;
563         if (buts->end_lba)
564                 bt->end_lba = buts->end_lba;
565 
566         bt->pid = buts->pid;
567         bt->trace_state = Blktrace_setup;
568 
569         rcu_assign_pointer(q->blk_trace, bt);
570         get_probe_ref();
571 
572         ret = 0;
573 err:
574         if (ret)
575                 blk_trace_free(bt);
576         return ret;
577 }
578 
579 static int __blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
580                              struct block_device *bdev, char __user *arg)
581 {
582         struct blk_user_trace_setup buts;
583         int ret;
584 
585         ret = copy_from_user(&buts, arg, sizeof(buts));
586         if (ret)
587                 return -EFAULT;
588 
589         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
590         if (ret)
591                 return ret;
592 
593         if (copy_to_user(arg, &buts, sizeof(buts))) {
594                 __blk_trace_remove(q);
595                 return -EFAULT;
596         }
597         return 0;
598 }
599 
600 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
601                     struct block_device *bdev,
602                     char __user *arg)
603 {
604         int ret;
605 
606         mutex_lock(&q->debugfs_mutex);
607         ret = __blk_trace_setup(q, name, dev, bdev, arg);
608         mutex_unlock(&q->debugfs_mutex);
609 
610         return ret;
611 }
612 EXPORT_SYMBOL_GPL(blk_trace_setup);
613 
614 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
615 static int compat_blk_trace_setup(struct request_queue *q, char *name,
616                                   dev_t dev, struct block_device *bdev,
617                                   char __user *arg)
618 {
619         struct blk_user_trace_setup buts;
620         struct compat_blk_user_trace_setup cbuts;
621         int ret;
622 
623         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
624                 return -EFAULT;
625 
626         buts = (struct blk_user_trace_setup) {
627                 .act_mask = cbuts.act_mask,
628                 .buf_size = cbuts.buf_size,
629                 .buf_nr = cbuts.buf_nr,
630                 .start_lba = cbuts.start_lba,
631                 .end_lba = cbuts.end_lba,
632                 .pid = cbuts.pid,
633         };
634 
635         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
636         if (ret)
637                 return ret;
638 
639         if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
640                 __blk_trace_remove(q);
641                 return -EFAULT;
642         }
643 
644         return 0;
645 }
646 #endif
647 
648 static int __blk_trace_startstop(struct request_queue *q, int start)
649 {
650         int ret;
651         struct blk_trace *bt;
652 
653         bt = rcu_dereference_protected(q->blk_trace,
654                                        lockdep_is_held(&q->debugfs_mutex));
655         if (bt == NULL)
656                 return -EINVAL;
657 
658         /*
659          * For starting a trace, we can transition from a setup or stopped
660          * trace. For stopping a trace, the state must be running
661          */
662         ret = -EINVAL;
663         if (start) {
664                 if (bt->trace_state == Blktrace_setup ||
665                     bt->trace_state == Blktrace_stopped) {
666                         blktrace_seq++;
667                         smp_mb();
668                         bt->trace_state = Blktrace_running;
669                         spin_lock_irq(&running_trace_lock);
670                         list_add(&bt->running_list, &running_trace_list);
671                         spin_unlock_irq(&running_trace_lock);
672 
673                         trace_note_time(bt);
674                         ret = 0;
675                 }
676         } else {
677                 if (bt->trace_state == Blktrace_running) {
678                         bt->trace_state = Blktrace_stopped;
679                         spin_lock_irq(&running_trace_lock);
680                         list_del_init(&bt->running_list);
681                         spin_unlock_irq(&running_trace_lock);
682                         relay_flush(bt->rchan);
683                         ret = 0;
684                 }
685         }
686 
687         return ret;
688 }
689 
690 int blk_trace_startstop(struct request_queue *q, int start)
691 {
692         int ret;
693 
694         mutex_lock(&q->debugfs_mutex);
695         ret = __blk_trace_startstop(q, start);
696         mutex_unlock(&q->debugfs_mutex);
697 
698         return ret;
699 }
700 EXPORT_SYMBOL_GPL(blk_trace_startstop);
701 
702 /*
703  * When reading or writing the blktrace sysfs files, the references to the
704  * opened sysfs or device files should prevent the underlying block device
705  * from being removed. So no further delete protection is really needed.
706  */
707 
708 /**
709  * blk_trace_ioctl: - handle the ioctls associated with tracing
710  * @bdev:       the block device
711  * @cmd:        the ioctl cmd
712  * @arg:        the argument data, if any
713  *
714  **/
715 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
716 {
717         struct request_queue *q;
718         int ret, start = 0;
719         char b[BDEVNAME_SIZE];
720 
721         q = bdev_get_queue(bdev);
722         if (!q)
723                 return -ENXIO;
724 
725         mutex_lock(&q->debugfs_mutex);
726 
727         switch (cmd) {
728         case BLKTRACESETUP:
729                 bdevname(bdev, b);
730                 ret = __blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
731                 break;
732 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
733         case BLKTRACESETUP32:
734                 bdevname(bdev, b);
735                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
736                 break;
737 #endif
738         case BLKTRACESTART:
739                 start = 1;
740                 fallthrough;
741         case BLKTRACESTOP:
742                 ret = __blk_trace_startstop(q, start);
743                 break;
744         case BLKTRACETEARDOWN:
745                 ret = __blk_trace_remove(q);
746                 break;
747         default:
748                 ret = -ENOTTY;
749                 break;
750         }
751 
752         mutex_unlock(&q->debugfs_mutex);
753         return ret;
754 }
755 
756 /**
757  * blk_trace_shutdown: - stop and cleanup trace structures
758  * @q:    the request queue associated with the device
759  *
760  **/
761 void blk_trace_shutdown(struct request_queue *q)
762 {
763         mutex_lock(&q->debugfs_mutex);
764         if (rcu_dereference_protected(q->blk_trace,
765                                       lockdep_is_held(&q->debugfs_mutex))) {
766                 __blk_trace_startstop(q, 0);
767                 __blk_trace_remove(q);
768         }
769 
770         mutex_unlock(&q->debugfs_mutex);
771 }
772 
773 #ifdef CONFIG_BLK_CGROUP
774 static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
775 {
776         struct blk_trace *bt;
777 
778         /* We don't use the 'bt' value here except as an optimization... */
779         bt = rcu_dereference_protected(q->blk_trace, 1);
780         if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
781                 return 0;
782 
783         if (!bio->bi_blkg)
784                 return 0;
785         return cgroup_id(bio_blkcg(bio)->css.cgroup);
786 }
787 #else
788 static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
789 {
790         return 0;
791 }
792 #endif
793 
794 static u64
795 blk_trace_request_get_cgid(struct request *rq)
796 {
797         if (!rq->bio)
798                 return 0;
799         /* Use the first bio */
800         return blk_trace_bio_get_cgid(rq->q, rq->bio);
801 }
802 
803 /*
804  * blktrace probes
805  */
806 
807 /**
808  * blk_add_trace_rq - Add a trace for a request oriented action
809  * @rq:         the source request
810  * @error:      return status to log
811  * @nr_bytes:   number of completed bytes
812  * @what:       the action
813  * @cgid:       the cgroup info
814  *
815  * Description:
816  *     Records an action against a request. Will log the bio offset + size.
817  *
818  **/
819 static void blk_add_trace_rq(struct request *rq, int error,
820                              unsigned int nr_bytes, u32 what, u64 cgid)
821 {
822         struct blk_trace *bt;
823 
824         rcu_read_lock();
825         bt = rcu_dereference(rq->q->blk_trace);
826         if (likely(!bt)) {
827                 rcu_read_unlock();
828                 return;
829         }
830 
831         if (blk_rq_is_passthrough(rq))
832                 what |= BLK_TC_ACT(BLK_TC_PC);
833         else
834                 what |= BLK_TC_ACT(BLK_TC_FS);
835 
836         __blk_add_trace(bt, blk_rq_trace_sector(rq), nr_bytes, req_op(rq),
837                         rq->cmd_flags, what, error, 0, NULL, cgid);
838         rcu_read_unlock();
839 }
840 
841 static void blk_add_trace_rq_insert(void *ignore, struct request *rq)
842 {
843         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_INSERT,
844                          blk_trace_request_get_cgid(rq));
845 }
846 
847 static void blk_add_trace_rq_issue(void *ignore, struct request *rq)
848 {
849         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_ISSUE,
850                          blk_trace_request_get_cgid(rq));
851 }
852 
853 static void blk_add_trace_rq_merge(void *ignore, struct request *rq)
854 {
855         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_BACKMERGE,
856                          blk_trace_request_get_cgid(rq));
857 }
858 
859 static void blk_add_trace_rq_requeue(void *ignore, struct request *rq)
860 {
861         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_REQUEUE,
862                          blk_trace_request_get_cgid(rq));
863 }
864 
865 static void blk_add_trace_rq_complete(void *ignore, struct request *rq,
866                         int error, unsigned int nr_bytes)
867 {
868         blk_add_trace_rq(rq, error, nr_bytes, BLK_TA_COMPLETE,
869                          blk_trace_request_get_cgid(rq));
870 }
871 
872 /**
873  * blk_add_trace_bio - Add a trace for a bio oriented action
874  * @q:          queue the io is for
875  * @bio:        the source bio
876  * @what:       the action
877  * @error:      error, if any
878  *
879  * Description:
880  *     Records an action against a bio. Will log the bio offset + size.
881  *
882  **/
883 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
884                               u32 what, int error)
885 {
886         struct blk_trace *bt;
887 
888         rcu_read_lock();
889         bt = rcu_dereference(q->blk_trace);
890         if (likely(!bt)) {
891                 rcu_read_unlock();
892                 return;
893         }
894 
895         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
896                         bio_op(bio), bio->bi_opf, what, error, 0, NULL,
897                         blk_trace_bio_get_cgid(q, bio));
898         rcu_read_unlock();
899 }
900 
901 static void blk_add_trace_bio_bounce(void *ignore, struct bio *bio)
902 {
903         blk_add_trace_bio(bio->bi_bdev->bd_disk->queue, bio, BLK_TA_BOUNCE, 0);
904 }
905 
906 static void blk_add_trace_bio_complete(void *ignore,
907                                        struct request_queue *q, struct bio *bio)
908 {
909         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE,
910                           blk_status_to_errno(bio->bi_status));
911 }
912 
913 static void blk_add_trace_bio_backmerge(void *ignore, struct bio *bio)
914 {
915         blk_add_trace_bio(bio->bi_bdev->bd_disk->queue, bio, BLK_TA_BACKMERGE,
916                         0);
917 }
918 
919 static void blk_add_trace_bio_frontmerge(void *ignore, struct bio *bio)
920 {
921         blk_add_trace_bio(bio->bi_bdev->bd_disk->queue, bio, BLK_TA_FRONTMERGE,
922                         0);
923 }
924 
925 static void blk_add_trace_bio_queue(void *ignore, struct bio *bio)
926 {
927         blk_add_trace_bio(bio->bi_bdev->bd_disk->queue, bio, BLK_TA_QUEUE, 0);
928 }
929 
930 static void blk_add_trace_getrq(void *ignore, struct bio *bio)
931 {
932         blk_add_trace_bio(bio->bi_bdev->bd_disk->queue, bio, BLK_TA_GETRQ, 0);
933 }
934 
935 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
936 {
937         struct blk_trace *bt;
938 
939         rcu_read_lock();
940         bt = rcu_dereference(q->blk_trace);
941         if (bt)
942                 __blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL, 0);
943         rcu_read_unlock();
944 }
945 
946 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
947                                     unsigned int depth, bool explicit)
948 {
949         struct blk_trace *bt;
950 
951         rcu_read_lock();
952         bt = rcu_dereference(q->blk_trace);
953         if (bt) {
954                 __be64 rpdu = cpu_to_be64(depth);
955                 u32 what;
956 
957                 if (explicit)
958                         what = BLK_TA_UNPLUG_IO;
959                 else
960                         what = BLK_TA_UNPLUG_TIMER;
961 
962                 __blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu, 0);
963         }
964         rcu_read_unlock();
965 }
966 
967 static void blk_add_trace_split(void *ignore, struct bio *bio, unsigned int pdu)
968 {
969         struct request_queue *q = bio->bi_bdev->bd_disk->queue;
970         struct blk_trace *bt;
971 
972         rcu_read_lock();
973         bt = rcu_dereference(q->blk_trace);
974         if (bt) {
975                 __be64 rpdu = cpu_to_be64(pdu);
976 
977                 __blk_add_trace(bt, bio->bi_iter.bi_sector,
978                                 bio->bi_iter.bi_size, bio_op(bio), bio->bi_opf,
979                                 BLK_TA_SPLIT,
980                                 blk_status_to_errno(bio->bi_status),
981                                 sizeof(rpdu), &rpdu,
982                                 blk_trace_bio_get_cgid(q, bio));
983         }
984         rcu_read_unlock();
985 }
986 
987 /**
988  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
989  * @ignore:     trace callback data parameter (not used)
990  * @bio:        the source bio
991  * @dev:        source device
992  * @from:       source sector
993  *
994  * Called after a bio is remapped to a different device and/or sector.
995  **/
996 static void blk_add_trace_bio_remap(void *ignore, struct bio *bio, dev_t dev,
997                                     sector_t from)
998 {
999         struct request_queue *q = bio->bi_bdev->bd_disk->queue;
1000         struct blk_trace *bt;
1001         struct blk_io_trace_remap r;
1002 
1003         rcu_read_lock();
1004         bt = rcu_dereference(q->blk_trace);
1005         if (likely(!bt)) {
1006                 rcu_read_unlock();
1007                 return;
1008         }
1009 
1010         r.device_from = cpu_to_be32(dev);
1011         r.device_to   = cpu_to_be32(bio_dev(bio));
1012         r.sector_from = cpu_to_be64(from);
1013 
1014         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
1015                         bio_op(bio), bio->bi_opf, BLK_TA_REMAP,
1016                         blk_status_to_errno(bio->bi_status),
1017                         sizeof(r), &r, blk_trace_bio_get_cgid(q, bio));
1018         rcu_read_unlock();
1019 }
1020 
1021 /**
1022  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
1023  * @ignore:     trace callback data parameter (not used)
1024  * @rq:         the source request
1025  * @dev:        target device
1026  * @from:       source sector
1027  *
1028  * Description:
1029  *     Device mapper remaps request to other devices.
1030  *     Add a trace for that action.
1031  *
1032  **/
1033 static void blk_add_trace_rq_remap(void *ignore, struct request *rq, dev_t dev,
1034                                    sector_t from)
1035 {
1036         struct blk_trace *bt;
1037         struct blk_io_trace_remap r;
1038 
1039         rcu_read_lock();
1040         bt = rcu_dereference(rq->q->blk_trace);
1041         if (likely(!bt)) {
1042                 rcu_read_unlock();
1043                 return;
1044         }
1045 
1046         r.device_from = cpu_to_be32(dev);
1047         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
1048         r.sector_from = cpu_to_be64(from);
1049 
1050         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
1051                         rq_data_dir(rq), 0, BLK_TA_REMAP, 0,
1052                         sizeof(r), &r, blk_trace_request_get_cgid(rq));
1053         rcu_read_unlock();
1054 }
1055 
1056 /**
1057  * blk_add_driver_data - Add binary message with driver-specific data
1058  * @rq:         io request
1059  * @data:       driver-specific data
1060  * @len:        length of driver-specific data
1061  *
1062  * Description:
1063  *     Some drivers might want to write driver-specific data per request.
1064  *
1065  **/
1066 void blk_add_driver_data(struct request *rq, void *data, size_t len)
1067 {
1068         struct blk_trace *bt;
1069 
1070         rcu_read_lock();
1071         bt = rcu_dereference(rq->q->blk_trace);
1072         if (likely(!bt)) {
1073                 rcu_read_unlock();
1074                 return;
1075         }
1076 
1077         __blk_add_trace(bt, blk_rq_trace_sector(rq), blk_rq_bytes(rq), 0, 0,
1078                                 BLK_TA_DRV_DATA, 0, len, data,
1079                                 blk_trace_request_get_cgid(rq));
1080         rcu_read_unlock();
1081 }
1082 EXPORT_SYMBOL_GPL(blk_add_driver_data);
1083 
1084 static void blk_register_tracepoints(void)
1085 {
1086         int ret;
1087 
1088         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1089         WARN_ON(ret);
1090         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1091         WARN_ON(ret);
1092         ret = register_trace_block_rq_merge(blk_add_trace_rq_merge, NULL);
1093         WARN_ON(ret);
1094         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1095         WARN_ON(ret);
1096         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1097         WARN_ON(ret);
1098         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1099         WARN_ON(ret);
1100         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1101         WARN_ON(ret);
1102         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1103         WARN_ON(ret);
1104         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1105         WARN_ON(ret);
1106         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1107         WARN_ON(ret);
1108         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1109         WARN_ON(ret);
1110         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1111         WARN_ON(ret);
1112         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1113         WARN_ON(ret);
1114         ret = register_trace_block_split(blk_add_trace_split, NULL);
1115         WARN_ON(ret);
1116         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1117         WARN_ON(ret);
1118         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1119         WARN_ON(ret);
1120 }
1121 
1122 static void blk_unregister_tracepoints(void)
1123 {
1124         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1125         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1126         unregister_trace_block_split(blk_add_trace_split, NULL);
1127         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1128         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1129         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1130         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1131         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1132         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1133         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1134         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1135         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1136         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1137         unregister_trace_block_rq_merge(blk_add_trace_rq_merge, NULL);
1138         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1139         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1140 
1141         tracepoint_synchronize_unregister();
1142 }
1143 
1144 /*
1145  * struct blk_io_tracer formatting routines
1146  */
1147 
1148 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1149 {
1150         int i = 0;
1151         int tc = t->action >> BLK_TC_SHIFT;
1152 
1153         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1154                 rwbs[i++] = 'N';
1155                 goto out;
1156         }
1157 
1158         if (tc & BLK_TC_FLUSH)
1159                 rwbs[i++] = 'F';
1160 
1161         if (tc & BLK_TC_DISCARD)
1162                 rwbs[i++] = 'D';
1163         else if (tc & BLK_TC_WRITE)
1164                 rwbs[i++] = 'W';
1165         else if (t->bytes)
1166                 rwbs[i++] = 'R';
1167         else
1168                 rwbs[i++] = 'N';
1169 
1170         if (tc & BLK_TC_FUA)
1171                 rwbs[i++] = 'F';
1172         if (tc & BLK_TC_AHEAD)
1173                 rwbs[i++] = 'A';
1174         if (tc & BLK_TC_SYNC)
1175                 rwbs[i++] = 'S';
1176         if (tc & BLK_TC_META)
1177                 rwbs[i++] = 'M';
1178 out:
1179         rwbs[i] = '\0';
1180 }
1181 
1182 static inline
1183 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1184 {
1185         return (const struct blk_io_trace *)ent;
1186 }
1187 
1188 static inline const void *pdu_start(const struct trace_entry *ent, bool has_cg)
1189 {
1190         return (void *)(te_blk_io_trace(ent) + 1) + (has_cg ? sizeof(u64) : 0);
1191 }
1192 
1193 static inline u64 t_cgid(const struct trace_entry *ent)
1194 {
1195         return *(u64 *)(te_blk_io_trace(ent) + 1);
1196 }
1197 
1198 static inline int pdu_real_len(const struct trace_entry *ent, bool has_cg)
1199 {
1200         return te_blk_io_trace(ent)->pdu_len - (has_cg ? sizeof(u64) : 0);
1201 }
1202 
1203 static inline u32 t_action(const struct trace_entry *ent)
1204 {
1205         return te_blk_io_trace(ent)->action;
1206 }
1207 
1208 static inline u32 t_bytes(const struct trace_entry *ent)
1209 {
1210         return te_blk_io_trace(ent)->bytes;
1211 }
1212 
1213 static inline u32 t_sec(const struct trace_entry *ent)
1214 {
1215         return te_blk_io_trace(ent)->bytes >> 9;
1216 }
1217 
1218 static inline unsigned long long t_sector(const struct trace_entry *ent)
1219 {
1220         return te_blk_io_trace(ent)->sector;
1221 }
1222 
1223 static inline __u16 t_error(const struct trace_entry *ent)
1224 {
1225         return te_blk_io_trace(ent)->error;
1226 }
1227 
1228 static __u64 get_pdu_int(const struct trace_entry *ent, bool has_cg)
1229 {
1230         const __be64 *val = pdu_start(ent, has_cg);
1231         return be64_to_cpu(*val);
1232 }
1233 
1234 typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act,
1235         bool has_cg);
1236 
1237 static void blk_log_action_classic(struct trace_iterator *iter, const char *act,
1238         bool has_cg)
1239 {
1240         char rwbs[RWBS_LEN];
1241         unsigned long long ts  = iter->ts;
1242         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1243         unsigned secs          = (unsigned long)ts;
1244         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1245 
1246         fill_rwbs(rwbs, t);
1247 
1248         trace_seq_printf(&iter->seq,
1249                          "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1250                          MAJOR(t->device), MINOR(t->device), iter->cpu,
1251                          secs, nsec_rem, iter->ent->pid, act, rwbs);
1252 }
1253 
1254 static void blk_log_action(struct trace_iterator *iter, const char *act,
1255         bool has_cg)
1256 {
1257         char rwbs[RWBS_LEN];
1258         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1259 
1260         fill_rwbs(rwbs, t);
1261         if (has_cg) {
1262                 u64 id = t_cgid(iter->ent);
1263 
1264                 if (blk_tracer_flags.val & TRACE_BLK_OPT_CGNAME) {
1265                         char blkcg_name_buf[NAME_MAX + 1] = "<...>";
1266 
1267                         cgroup_path_from_kernfs_id(id, blkcg_name_buf,
1268                                 sizeof(blkcg_name_buf));
1269                         trace_seq_printf(&iter->seq, "%3d,%-3d %s %2s %3s ",
1270                                  MAJOR(t->device), MINOR(t->device),
1271                                  blkcg_name_buf, act, rwbs);
1272                 } else {
1273                         /*
1274                          * The cgid portion used to be "INO,GEN".  Userland
1275                          * builds a FILEID_INO32_GEN fid out of them and
1276                          * opens the cgroup using open_by_handle_at(2).
1277                          * While 32bit ino setups are still the same, 64bit
1278                          * ones now use the 64bit ino as the whole ID and
1279                          * no longer use generation.
1280                          *
1281                          * Regardless of the content, always output
1282                          * "LOW32,HIGH32" so that FILEID_INO32_GEN fid can
1283                          * be mapped back to @id on both 64 and 32bit ino
1284                          * setups.  See __kernfs_fh_to_dentry().
1285                          */
1286                         trace_seq_printf(&iter->seq,
1287                                  "%3d,%-3d %llx,%-llx %2s %3s ",
1288                                  MAJOR(t->device), MINOR(t->device),
1289                                  id & U32_MAX, id >> 32, act, rwbs);
1290                 }
1291         } else
1292                 trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1293                                  MAJOR(t->device), MINOR(t->device), act, rwbs);
1294 }
1295 
1296 static void blk_log_dump_pdu(struct trace_seq *s,
1297         const struct trace_entry *ent, bool has_cg)
1298 {
1299         const unsigned char *pdu_buf;
1300         int pdu_len;
1301         int i, end;
1302 
1303         pdu_buf = pdu_start(ent, has_cg);
1304         pdu_len = pdu_real_len(ent, has_cg);
1305 
1306         if (!pdu_len)
1307                 return;
1308 
1309         /* find the last zero that needs to be printed */
1310         for (end = pdu_len - 1; end >= 0; end--)
1311                 if (pdu_buf[end])
1312                         break;
1313         end++;
1314 
1315         trace_seq_putc(s, '(');
1316 
1317         for (i = 0; i < pdu_len; i++) {
1318 
1319                 trace_seq_printf(s, "%s%02x",
1320                                  i == 0 ? "" : " ", pdu_buf[i]);
1321 
1322                 /*
1323                  * stop when the rest is just zeros and indicate so
1324                  * with a ".." appended
1325                  */
1326                 if (i == end && end != pdu_len - 1) {
1327                         trace_seq_puts(s, " ..) ");
1328                         return;
1329                 }
1330         }
1331 
1332         trace_seq_puts(s, ") ");
1333 }
1334 
1335 static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1336 {
1337         char cmd[TASK_COMM_LEN];
1338 
1339         trace_find_cmdline(ent->pid, cmd);
1340 
1341         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1342                 trace_seq_printf(s, "%u ", t_bytes(ent));
1343                 blk_log_dump_pdu(s, ent, has_cg);
1344                 trace_seq_printf(s, "[%s]\n", cmd);
1345         } else {
1346                 if (t_sec(ent))
1347                         trace_seq_printf(s, "%llu + %u [%s]\n",
1348                                                 t_sector(ent), t_sec(ent), cmd);
1349                 else
1350                         trace_seq_printf(s, "[%s]\n", cmd);
1351         }
1352 }
1353 
1354 static void blk_log_with_error(struct trace_seq *s,
1355                               const struct trace_entry *ent, bool has_cg)
1356 {
1357         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1358                 blk_log_dump_pdu(s, ent, has_cg);
1359                 trace_seq_printf(s, "[%d]\n", t_error(ent));
1360         } else {
1361                 if (t_sec(ent))
1362                         trace_seq_printf(s, "%llu + %u [%d]\n",
1363                                          t_sector(ent),
1364                                          t_sec(ent), t_error(ent));
1365                 else
1366                         trace_seq_printf(s, "%llu [%d]\n",
1367                                          t_sector(ent), t_error(ent));
1368         }
1369 }
1370 
1371 static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1372 {
1373         const struct blk_io_trace_remap *__r = pdu_start(ent, has_cg);
1374 
1375         trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1376                          t_sector(ent), t_sec(ent),
1377                          MAJOR(be32_to_cpu(__r->device_from)),
1378                          MINOR(be32_to_cpu(__r->device_from)),
1379                          be64_to_cpu(__r->sector_from));
1380 }
1381 
1382 static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1383 {
1384         char cmd[TASK_COMM_LEN];
1385 
1386         trace_find_cmdline(ent->pid, cmd);
1387 
1388         trace_seq_printf(s, "[%s]\n", cmd);
1389 }
1390 
1391 static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1392 {
1393         char cmd[TASK_COMM_LEN];
1394 
1395         trace_find_cmdline(ent->pid, cmd);
1396 
1397         trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent, has_cg));
1398 }
1399 
1400 static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1401 {
1402         char cmd[TASK_COMM_LEN];
1403 
1404         trace_find_cmdline(ent->pid, cmd);
1405 
1406         trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1407                          get_pdu_int(ent, has_cg), cmd);
1408 }
1409 
1410 static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent,
1411                         bool has_cg)
1412 {
1413 
1414         trace_seq_putmem(s, pdu_start(ent, has_cg),
1415                 pdu_real_len(ent, has_cg));
1416         trace_seq_putc(s, '\n');
1417 }
1418 
1419 /*
1420  * struct tracer operations
1421  */
1422 
1423 static void blk_tracer_print_header(struct seq_file *m)
1424 {
1425         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1426                 return;
1427         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1428                     "#  |     |     |           |   |   |\n");
1429 }
1430 
1431 static void blk_tracer_start(struct trace_array *tr)
1432 {
1433         blk_tracer_enabled = true;
1434 }
1435 
1436 static int blk_tracer_init(struct trace_array *tr)
1437 {
1438         blk_tr = tr;
1439         blk_tracer_start(tr);
1440         return 0;
1441 }
1442 
1443 static void blk_tracer_stop(struct trace_array *tr)
1444 {
1445         blk_tracer_enabled = false;
1446 }
1447 
1448 static void blk_tracer_reset(struct trace_array *tr)
1449 {
1450         blk_tracer_stop(tr);
1451 }
1452 
1453 static const struct {
1454         const char *act[2];
1455         void       (*print)(struct trace_seq *s, const struct trace_entry *ent,
1456                             bool has_cg);
1457 } what2act[] = {
1458         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1459         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1460         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1461         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1462         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1463         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1464         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1465         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1466         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1467         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1468         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1469         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1470         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1471         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1472         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1473 };
1474 
1475 static enum print_line_t print_one_line(struct trace_iterator *iter,
1476                                         bool classic)
1477 {
1478         struct trace_array *tr = iter->tr;
1479         struct trace_seq *s = &iter->seq;
1480         const struct blk_io_trace *t;
1481         u16 what;
1482         bool long_act;
1483         blk_log_action_t *log_action;
1484         bool has_cg;
1485 
1486         t          = te_blk_io_trace(iter->ent);
1487         what       = (t->action & ((1 << BLK_TC_SHIFT) - 1)) & ~__BLK_TA_CGROUP;
1488         long_act   = !!(tr->trace_flags & TRACE_ITER_VERBOSE);
1489         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1490         has_cg     = t->action & __BLK_TA_CGROUP;
1491 
1492         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1493                 log_action(iter, long_act ? "message" : "m", has_cg);
1494                 blk_log_msg(s, iter->ent, has_cg);
1495                 return trace_handle_return(s);
1496         }
1497 
1498         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1499                 trace_seq_printf(s, "Unknown action %x\n", what);
1500         else {
1501                 log_action(iter, what2act[what].act[long_act], has_cg);
1502                 what2act[what].print(s, iter->ent, has_cg);
1503         }
1504 
1505         return trace_handle_return(s);
1506 }
1507 
1508 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1509                                                int flags, struct trace_event *event)
1510 {
1511         return print_one_line(iter, false);
1512 }
1513 
1514 static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1515 {
1516         struct trace_seq *s = &iter->seq;
1517         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1518         const int offset = offsetof(struct blk_io_trace, sector);
1519         struct blk_io_trace old = {
1520                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1521                 .time     = iter->ts,
1522         };
1523 
1524         trace_seq_putmem(s, &old, offset);
1525         trace_seq_putmem(s, &t->sector,
1526                          sizeof(old) - offset + t->pdu_len);
1527 }
1528 
1529 static enum print_line_t
1530 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1531                              struct trace_event *event)
1532 {
1533         blk_trace_synthesize_old_trace(iter);
1534 
1535         return trace_handle_return(&iter->seq);
1536 }
1537 
1538 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1539 {
1540         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1541                 return TRACE_TYPE_UNHANDLED;
1542 
1543         return print_one_line(iter, true);
1544 }
1545 
1546 static int
1547 blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1548 {
1549         /* don't output context-info for blk_classic output */
1550         if (bit == TRACE_BLK_OPT_CLASSIC) {
1551                 if (set)
1552                         tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1553                 else
1554                         tr->trace_flags |= TRACE_ITER_CONTEXT_INFO;
1555         }
1556         return 0;
1557 }
1558 
1559 static struct tracer blk_tracer __read_mostly = {
1560         .name           = "blk",
1561         .init           = blk_tracer_init,
1562         .reset          = blk_tracer_reset,
1563         .start          = blk_tracer_start,
1564         .stop           = blk_tracer_stop,
1565         .print_header   = blk_tracer_print_header,
1566         .print_line     = blk_tracer_print_line,
1567         .flags          = &blk_tracer_flags,
1568         .set_flag       = blk_tracer_set_flag,
1569 };
1570 
1571 static struct trace_event_functions trace_blk_event_funcs = {
1572         .trace          = blk_trace_event_print,
1573         .binary         = blk_trace_event_print_binary,
1574 };
1575 
1576 static struct trace_event trace_blk_event = {
1577         .type           = TRACE_BLK,
1578         .funcs          = &trace_blk_event_funcs,
1579 };
1580 
1581 static int __init init_blk_tracer(void)
1582 {
1583         if (!register_trace_event(&trace_blk_event)) {
1584                 pr_warn("Warning: could not register block events\n");
1585                 return 1;
1586         }
1587 
1588         if (register_tracer(&blk_tracer) != 0) {
1589                 pr_warn("Warning: could not register the block tracer\n");
1590                 unregister_trace_event(&trace_blk_event);
1591                 return 1;
1592         }
1593 
1594         return 0;
1595 }
1596 
1597 device_initcall(init_blk_tracer);
1598 
1599 static int blk_trace_remove_queue(struct request_queue *q)
1600 {
1601         struct blk_trace *bt;
1602 
1603         bt = rcu_replace_pointer(q->blk_trace, NULL,
1604                                  lockdep_is_held(&q->debugfs_mutex));
1605         if (bt == NULL)
1606                 return -EINVAL;
1607 
1608         if (bt->trace_state == Blktrace_running) {
1609                 bt->trace_state = Blktrace_stopped;
1610                 spin_lock_irq(&running_trace_lock);
1611                 list_del_init(&bt->running_list);
1612                 spin_unlock_irq(&running_trace_lock);
1613                 relay_flush(bt->rchan);
1614         }
1615 
1616         put_probe_ref();
1617         synchronize_rcu();
1618         blk_trace_free(bt);
1619         return 0;
1620 }
1621 
1622 /*
1623  * Setup everything required to start tracing
1624  */
1625 static int blk_trace_setup_queue(struct request_queue *q,
1626                                  struct block_device *bdev)
1627 {
1628         struct blk_trace *bt = NULL;
1629         int ret = -ENOMEM;
1630 
1631         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1632         if (!bt)
1633                 return -ENOMEM;
1634 
1635         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1636         if (!bt->msg_data)
1637                 goto free_bt;
1638 
1639         bt->dev = bdev->bd_dev;
1640         bt->act_mask = (u16)-1;
1641 
1642         blk_trace_setup_lba(bt, bdev);
1643 
1644         rcu_assign_pointer(q->blk_trace, bt);
1645         get_probe_ref();
1646         return 0;
1647 
1648 free_bt:
1649         blk_trace_free(bt);
1650         return ret;
1651 }
1652 
1653 /*
1654  * sysfs interface to enable and configure tracing
1655  */
1656 
1657 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1658                                          struct device_attribute *attr,
1659                                          char *buf);
1660 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1661                                           struct device_attribute *attr,
1662                                           const char *buf, size_t count);
1663 #define BLK_TRACE_DEVICE_ATTR(_name) \
1664         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1665                     sysfs_blk_trace_attr_show, \
1666                     sysfs_blk_trace_attr_store)
1667 
1668 static BLK_TRACE_DEVICE_ATTR(enable);
1669 static BLK_TRACE_DEVICE_ATTR(act_mask);
1670 static BLK_TRACE_DEVICE_ATTR(pid);
1671 static BLK_TRACE_DEVICE_ATTR(start_lba);
1672 static BLK_TRACE_DEVICE_ATTR(end_lba);
1673 
1674 static struct attribute *blk_trace_attrs[] = {
1675         &dev_attr_enable.attr,
1676         &dev_attr_act_mask.attr,
1677         &dev_attr_pid.attr,
1678         &dev_attr_start_lba.attr,
1679         &dev_attr_end_lba.attr,
1680         NULL
1681 };
1682 
1683 struct attribute_group blk_trace_attr_group = {
1684         .name  = "trace",
1685         .attrs = blk_trace_attrs,
1686 };
1687 
1688 static const struct {
1689         int mask;
1690         const char *str;
1691 } mask_maps[] = {
1692         { BLK_TC_READ,          "read"          },
1693         { BLK_TC_WRITE,         "write"         },
1694         { BLK_TC_FLUSH,         "flush"         },
1695         { BLK_TC_SYNC,          "sync"          },
1696         { BLK_TC_QUEUE,         "queue"         },
1697         { BLK_TC_REQUEUE,       "requeue"       },
1698         { BLK_TC_ISSUE,         "issue"         },
1699         { BLK_TC_COMPLETE,      "complete"      },
1700         { BLK_TC_FS,            "fs"            },
1701         { BLK_TC_PC,            "pc"            },
1702         { BLK_TC_NOTIFY,        "notify"        },
1703         { BLK_TC_AHEAD,         "ahead"         },
1704         { BLK_TC_META,          "meta"          },
1705         { BLK_TC_DISCARD,       "discard"       },
1706         { BLK_TC_DRV_DATA,      "drv_data"      },
1707         { BLK_TC_FUA,           "fua"           },
1708 };
1709 
1710 static int blk_trace_str2mask(const char *str)
1711 {
1712         int i;
1713         int mask = 0;
1714         char *buf, *s, *token;
1715 
1716         buf = kstrdup(str, GFP_KERNEL);
1717         if (buf == NULL)
1718                 return -ENOMEM;
1719         s = strstrip(buf);
1720 
1721         while (1) {
1722                 token = strsep(&s, ",");
1723                 if (token == NULL)
1724                         break;
1725 
1726                 if (*token == '\0')
1727                         continue;
1728 
1729                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1730                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1731                                 mask |= mask_maps[i].mask;
1732                                 break;
1733                         }
1734                 }
1735                 if (i == ARRAY_SIZE(mask_maps)) {
1736                         mask = -EINVAL;
1737                         break;
1738                 }
1739         }
1740         kfree(buf);
1741 
1742         return mask;
1743 }
1744 
1745 static ssize_t blk_trace_mask2str(char *buf, int mask)
1746 {
1747         int i;
1748         char *p = buf;
1749 
1750         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1751                 if (mask & mask_maps[i].mask) {
1752                         p += sprintf(p, "%s%s",
1753                                     (p == buf) ? "" : ",", mask_maps[i].str);
1754                 }
1755         }
1756         *p++ = '\n';
1757 
1758         return p - buf;
1759 }
1760 
1761 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1762                                          struct device_attribute *attr,
1763                                          char *buf)
1764 {
1765         struct block_device *bdev = dev_to_bdev(dev);
1766         struct request_queue *q = bdev_get_queue(bdev);
1767         struct blk_trace *bt;
1768         ssize_t ret = -ENXIO;
1769 
1770         mutex_lock(&q->debugfs_mutex);
1771 
1772         bt = rcu_dereference_protected(q->blk_trace,
1773                                        lockdep_is_held(&q->debugfs_mutex));
1774         if (attr == &dev_attr_enable) {
1775                 ret = sprintf(buf, "%u\n", !!bt);
1776                 goto out_unlock_bdev;
1777         }
1778 
1779         if (bt == NULL)
1780                 ret = sprintf(buf, "disabled\n");
1781         else if (attr == &dev_attr_act_mask)
1782                 ret = blk_trace_mask2str(buf, bt->act_mask);
1783         else if (attr == &dev_attr_pid)
1784                 ret = sprintf(buf, "%u\n", bt->pid);
1785         else if (attr == &dev_attr_start_lba)
1786                 ret = sprintf(buf, "%llu\n", bt->start_lba);
1787         else if (attr == &dev_attr_end_lba)
1788                 ret = sprintf(buf, "%llu\n", bt->end_lba);
1789 
1790 out_unlock_bdev:
1791         mutex_unlock(&q->debugfs_mutex);
1792         return ret;
1793 }
1794 
1795 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1796                                           struct device_attribute *attr,
1797                                           const char *buf, size_t count)
1798 {
1799         struct block_device *bdev = dev_to_bdev(dev);
1800         struct request_queue *q = bdev_get_queue(bdev);
1801         struct blk_trace *bt;
1802         u64 value;
1803         ssize_t ret = -EINVAL;
1804 
1805         if (count == 0)
1806                 goto out;
1807 
1808         if (attr == &dev_attr_act_mask) {
1809                 if (kstrtoull(buf, 0, &value)) {
1810                         /* Assume it is a list of trace category names */
1811                         ret = blk_trace_str2mask(buf);
1812                         if (ret < 0)
1813                                 goto out;
1814                         value = ret;
1815                 }
1816         } else {
1817                 if (kstrtoull(buf, 0, &value))
1818                         goto out;
1819         }
1820 
1821         mutex_lock(&q->debugfs_mutex);
1822 
1823         bt = rcu_dereference_protected(q->blk_trace,
1824                                        lockdep_is_held(&q->debugfs_mutex));
1825         if (attr == &dev_attr_enable) {
1826                 if (!!value == !!bt) {
1827                         ret = 0;
1828                         goto out_unlock_bdev;
1829                 }
1830                 if (value)
1831                         ret = blk_trace_setup_queue(q, bdev);
1832                 else
1833                         ret = blk_trace_remove_queue(q);
1834                 goto out_unlock_bdev;
1835         }
1836 
1837         ret = 0;
1838         if (bt == NULL) {
1839                 ret = blk_trace_setup_queue(q, bdev);
1840                 bt = rcu_dereference_protected(q->blk_trace,
1841                                 lockdep_is_held(&q->debugfs_mutex));
1842         }
1843 
1844         if (ret == 0) {
1845                 if (attr == &dev_attr_act_mask)
1846                         bt->act_mask = value;
1847                 else if (attr == &dev_attr_pid)
1848                         bt->pid = value;
1849                 else if (attr == &dev_attr_start_lba)
1850                         bt->start_lba = value;
1851                 else if (attr == &dev_attr_end_lba)
1852                         bt->end_lba = value;
1853         }
1854 
1855 out_unlock_bdev:
1856         mutex_unlock(&q->debugfs_mutex);
1857 out:
1858         return ret ? ret : count;
1859 }
1860 
1861 int blk_trace_init_sysfs(struct device *dev)
1862 {
1863         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1864 }
1865 
1866 void blk_trace_remove_sysfs(struct device *dev)
1867 {
1868         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1869 }
1870 
1871 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1872 
1873 #ifdef CONFIG_EVENT_TRACING
1874 
1875 /**
1876  * blk_fill_rwbs - Fill the buffer rwbs by mapping op to character string.
1877  * @rwbs:       buffer to be filled
1878  * @op:         REQ_OP_XXX for the tracepoint
1879  *
1880  * Description:
1881  *     Maps the REQ_OP_XXX to character and fills the buffer provided by the
1882  *     caller with resulting string.
1883  *
1884  **/
1885 void blk_fill_rwbs(char *rwbs, unsigned int op)
1886 {
1887         int i = 0;
1888 
1889         if (op & REQ_PREFLUSH)
1890                 rwbs[i++] = 'F';
1891 
1892         switch (op & REQ_OP_MASK) {
1893         case REQ_OP_WRITE:
1894         case REQ_OP_WRITE_SAME:
1895                 rwbs[i++] = 'W';
1896                 break;
1897         case REQ_OP_DISCARD:
1898                 rwbs[i++] = 'D';
1899                 break;
1900         case REQ_OP_SECURE_ERASE:
1901                 rwbs[i++] = 'D';
1902                 rwbs[i++] = 'E';
1903                 break;
1904         case REQ_OP_FLUSH:
1905                 rwbs[i++] = 'F';
1906                 break;
1907         case REQ_OP_READ:
1908                 rwbs[i++] = 'R';
1909                 break;
1910         default:
1911                 rwbs[i++] = 'N';
1912         }
1913 
1914         if (op & REQ_FUA)
1915                 rwbs[i++] = 'F';
1916         if (op & REQ_RAHEAD)
1917                 rwbs[i++] = 'A';
1918         if (op & REQ_SYNC)
1919                 rwbs[i++] = 'S';
1920         if (op & REQ_META)
1921                 rwbs[i++] = 'M';
1922 
1923         rwbs[i] = '\0';
1924 }
1925 EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1926 
1927 #endif /* CONFIG_EVENT_TRACING */
1928 
1929 

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