kernel/trace/blktrace.c

   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(blk_tr, 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 timespec64 now;
 131         unsigned long flags;
 132         u32 words[2];
 133
 134         /* need to check user space to see if this breaks in y2038 or y2106 */
 135         ktime_get_real_ts64(&now);
 136         words[0] = (u32)now.tv_sec;
 137         words[1] = now.tv_nsec;
 138
 139         local_irq_save(flags);
 140         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
 141         local_irq_restore(flags);
 142 }
 143
 144 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 145 {
 146         int n;
 147         va_list args;
 148         unsigned long flags;
 149         char *buf;
 150
 151         if (unlikely(bt->trace_state != Blktrace_running &&
 152                      !blk_tracer_enabled))
 153                 return;
 154
 155         /*
 156          * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
 157          * message to the trace.
 158          */
 159         if (!(bt->act_mask & BLK_TC_NOTIFY))
 160                 return;
 161
 162         local_irq_save(flags);
 163         buf = this_cpu_ptr(bt->msg_data);
 164         va_start(args, fmt);
 165         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 166         va_end(args);
 167
 168         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
 169         local_irq_restore(flags);
 170 }
 171 EXPORT_SYMBOL_GPL(__trace_note_message);
 172
 173 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
 174                          pid_t pid)
 175 {
 176         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
 177                 return 1;
 178         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
 179                 return 1;
 180         if (bt->pid && pid != bt->pid)
 181                 return 1;
 182
 183         return 0;
 184 }
 185
 186 /*
 187  * Data direction bit lookup
 188  */
 189 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
 190                                  BLK_TC_ACT(BLK_TC_WRITE) };
 191
 192 #define BLK_TC_RAHEAD           BLK_TC_AHEAD
 193 #define BLK_TC_PREFLUSH         BLK_TC_FLUSH
 194
 195 /* The ilog2() calls fall out because they're constant */
 196 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
 197           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
 198
 199 /*
 200  * The worker for the various blk_add_trace*() types. Fills out a
 201  * blk_io_trace structure and places it in a per-cpu subbuffer.
 202  */
 203 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 204                      int op, int op_flags, u32 what, int error, int pdu_len,
 205                      void *pdu_data)
 206 {
 207         struct task_struct *tsk = current;
 208         struct ring_buffer_event *event = NULL;
 209         struct ring_buffer *buffer = NULL;
 210         struct blk_io_trace *t;
 211         unsigned long flags = 0;
 212         unsigned long *sequence;
 213         pid_t pid;
 214         int cpu, pc = 0;
 215         bool blk_tracer = blk_tracer_enabled;
 216
 217         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
 218                 return;
 219
 220         what |= ddir_act[op_is_write(op) ? WRITE : READ];
 221         what |= MASK_TC_BIT(op_flags, SYNC);
 222         what |= MASK_TC_BIT(op_flags, RAHEAD);
 223         what |= MASK_TC_BIT(op_flags, META);
 224         what |= MASK_TC_BIT(op_flags, PREFLUSH);
 225         what |= MASK_TC_BIT(op_flags, FUA);
 226         if (op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE)
 227                 what |= BLK_TC_ACT(BLK_TC_DISCARD);
 228         if (op == REQ_OP_FLUSH)
 229                 what |= BLK_TC_ACT(BLK_TC_FLUSH);
 230
 231         pid = tsk->pid;
 232         if (act_log_check(bt, what, sector, pid))
 233                 return;
 234         cpu = raw_smp_processor_id();
 235
 236         if (blk_tracer) {
 237                 tracing_record_cmdline(current);
 238
 239                 buffer = blk_tr->trace_buffer.buffer;
 240                 pc = preempt_count();
 241                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 242                                                   sizeof(*t) + pdu_len,
 243                                                   0, pc);
 244                 if (!event)
 245                         return;
 246                 t = ring_buffer_event_data(event);
 247                 goto record_it;
 248         }
 249
 250         if (unlikely(tsk->btrace_seq != blktrace_seq))
 251                 trace_note_tsk(tsk);
 252
 253         /*
 254          * A word about the locking here - we disable interrupts to reserve
 255          * some space in the relay per-cpu buffer, to prevent an irq
 256          * from coming in and stepping on our toes.
 257          */
 258         local_irq_save(flags);
 259         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
 260         if (t) {
 261                 sequence = per_cpu_ptr(bt->sequence, cpu);
 262
 263                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 264                 t->sequence = ++(*sequence);
 265                 t->time = ktime_to_ns(ktime_get());
 266 record_it:
 267                 /*
 268                  * These two are not needed in ftrace as they are in the
 269                  * generic trace_entry, filled by tracing_generic_entry_update,
 270                  * but for the trace_event->bin() synthesizer benefit we do it
 271                  * here too.
 272                  */
 273                 t->cpu = cpu;
 274                 t->pid = pid;
 275
 276                 t->sector = sector;
 277                 t->bytes = bytes;
 278                 t->action = what;
 279                 t->device = bt->dev;
 280                 t->error = error;
 281                 t->pdu_len = pdu_len;
 282
 283                 if (pdu_len)
 284                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
 285
 286                 if (blk_tracer) {
 287                         trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
 288                         return;
 289                 }
 290         }
 291
 292         local_irq_restore(flags);
 293 }
 294
 295 static struct dentry *blk_tree_root;
 296 static DEFINE_MUTEX(blk_tree_mutex);
 297
 298 static void blk_trace_free(struct blk_trace *bt)
 299 {
 300         debugfs_remove(bt->msg_file);
 301         debugfs_remove(bt->dropped_file);
 302         relay_close(bt->rchan);
 303         debugfs_remove(bt->dir);
 304         free_percpu(bt->sequence);
 305         free_percpu(bt->msg_data);
 306         kfree(bt);
 307 }
 308
 309 static void blk_trace_cleanup(struct blk_trace *bt)
 310 {
 311         blk_trace_free(bt);
 312         if (atomic_dec_and_test(&blk_probes_ref))
 313                 blk_unregister_tracepoints();
 314 }
 315
 316 int blk_trace_remove(struct request_queue *q)
 317 {
 318         struct blk_trace *bt;
 319
 320         bt = xchg(&q->blk_trace, NULL);
 321         if (!bt)
 322                 return -EINVAL;
 323
 324         if (bt->trace_state != Blktrace_running)
 325                 blk_trace_cleanup(bt);
 326
 327         return 0;
 328 }
 329 EXPORT_SYMBOL_GPL(blk_trace_remove);
 330
 331 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
 332                                 size_t count, loff_t *ppos)
 333 {
 334         struct blk_trace *bt = filp->private_data;
 335         char buf[16];
 336
 337         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
 338
 339         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 340 }
 341
 342 static const struct file_operations blk_dropped_fops = {
 343         .owner =        THIS_MODULE,
 344         .open =         simple_open,
 345         .read =         blk_dropped_read,
 346         .llseek =       default_llseek,
 347 };
 348
 349 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 350                                 size_t count, loff_t *ppos)
 351 {
 352         char *msg;
 353         struct blk_trace *bt;
 354
 355         if (count >= BLK_TN_MAX_MSG)
 356                 return -EINVAL;
 357
 358         msg = memdup_user_nul(buffer, count);
 359         if (IS_ERR(msg))
 360                 return PTR_ERR(msg);
 361
 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 *bt = NULL;
 441         struct dentry *dir = NULL;
 442         int ret;
 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         strreplace(buts->name, '/', '_');
 455
 456         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 457         if (!bt)
 458                 return -ENOMEM;
 459
 460         ret = -ENOMEM;
 461         bt->sequence = alloc_percpu(unsigned long);
 462         if (!bt->sequence)
 463                 goto err;
 464
 465         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 466         if (!bt->msg_data)
 467                 goto err;
 468
 469         ret = -ENOENT;
 470
 471         mutex_lock(&blk_tree_mutex);
 472         if (!blk_tree_root) {
 473                 blk_tree_root = debugfs_create_dir("block", NULL);
 474                 if (!blk_tree_root) {
 475                         mutex_unlock(&blk_tree_mutex);
 476                         goto err;
 477                 }
 478         }
 479         mutex_unlock(&blk_tree_mutex);
 480
 481         dir = debugfs_create_dir(buts->name, blk_tree_root);
 482
 483         if (!dir)
 484                 goto err;
 485
 486         bt->dir = dir;
 487         bt->dev = dev;
 488         atomic_set(&bt->dropped, 0);
 489         INIT_LIST_HEAD(&bt->running_list);
 490
 491         ret = -EIO;
 492         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 493                                                &blk_dropped_fops);
 494         if (!bt->dropped_file)
 495                 goto err;
 496
 497         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 498         if (!bt->msg_file)
 499                 goto err;
 500
 501         bt->rchan = relay_open("trace", dir, buts->buf_size,
 502                                 buts->buf_nr, &blk_relay_callbacks, bt);
 503         if (!bt->rchan)
 504                 goto err;
 505
 506         bt->act_mask = buts->act_mask;
 507         if (!bt->act_mask)
 508                 bt->act_mask = (u16) -1;
 509
 510         blk_trace_setup_lba(bt, bdev);
 511
 512         /* overwrite with user settings */
 513         if (buts->start_lba)
 514                 bt->start_lba = buts->start_lba;
 515         if (buts->end_lba)
 516                 bt->end_lba = buts->end_lba;
 517
 518         bt->pid = buts->pid;
 519         bt->trace_state = Blktrace_setup;
 520
 521         ret = -EBUSY;
 522         if (cmpxchg(&q->blk_trace, NULL, bt))
 523                 goto err;
 524
 525         if (atomic_inc_return(&blk_probes_ref) == 1)
 526                 blk_register_tracepoints();
 527
 528         return 0;
 529 err:
 530         blk_trace_free(bt);
 531         return ret;
 532 }
 533
 534 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 535                     struct block_device *bdev,
 536                     char __user *arg)
 537 {
 538         struct blk_user_trace_setup buts;
 539         int ret;
 540
 541         ret = copy_from_user(&buts, arg, sizeof(buts));
 542         if (ret)
 543                 return -EFAULT;
 544
 545         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 546         if (ret)
 547                 return ret;
 548
 549         if (copy_to_user(arg, &buts, sizeof(buts))) {
 550                 blk_trace_remove(q);
 551                 return -EFAULT;
 552         }
 553         return 0;
 554 }
 555 EXPORT_SYMBOL_GPL(blk_trace_setup);
 556
 557 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 558 static int compat_blk_trace_setup(struct request_queue *q, char *name,
 559                                   dev_t dev, struct block_device *bdev,
 560                                   char __user *arg)
 561 {
 562         struct blk_user_trace_setup buts;
 563         struct compat_blk_user_trace_setup cbuts;
 564         int ret;
 565
 566         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
 567                 return -EFAULT;
 568
 569         buts = (struct blk_user_trace_setup) {
 570                 .act_mask = cbuts.act_mask,
 571                 .buf_size = cbuts.buf_size,
 572                 .buf_nr = cbuts.buf_nr,
 573                 .start_lba = cbuts.start_lba,
 574                 .end_lba = cbuts.end_lba,
 575                 .pid = cbuts.pid,
 576         };
 577
 578         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 579         if (ret)
 580                 return ret;
 581
 582         if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
 583                 blk_trace_remove(q);
 584                 return -EFAULT;
 585         }
 586
 587         return 0;
 588 }
 589 #endif
 590
 591 int blk_trace_startstop(struct request_queue *q, int start)
 592 {
 593         int ret;
 594         struct blk_trace *bt = q->blk_trace;
 595
 596         if (bt == NULL)
 597                 return -EINVAL;
 598
 599         /*
 600          * For starting a trace, we can transition from a setup or stopped
 601          * trace. For stopping a trace, the state must be running
 602          */
 603         ret = -EINVAL;
 604         if (start) {
 605                 if (bt->trace_state == Blktrace_setup ||
 606                     bt->trace_state == Blktrace_stopped) {
 607                         blktrace_seq++;
 608                         smp_mb();
 609                         bt->trace_state = Blktrace_running;
 610                         spin_lock_irq(&running_trace_lock);
 611                         list_add(&bt->running_list, &running_trace_list);
 612                         spin_unlock_irq(&running_trace_lock);
 613
 614                         trace_note_time(bt);
 615                         ret = 0;
 616                 }
 617         } else {
 618                 if (bt->trace_state == Blktrace_running) {
 619                         bt->trace_state = Blktrace_stopped;
 620                         spin_lock_irq(&running_trace_lock);
 621                         list_del_init(&bt->running_list);
 622                         spin_unlock_irq(&running_trace_lock);
 623                         relay_flush(bt->rchan);
 624                         ret = 0;
 625                 }
 626         }
 627
 628         return ret;
 629 }
 630 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 631
 632 /**
 633  * blk_trace_ioctl: - handle the ioctls associated with tracing
 634  * @bdev:       the block device
 635  * @cmd:        the ioctl cmd
 636  * @arg:        the argument data, if any
 637  *
 638  **/
 639 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 640 {
 641         struct request_queue *q;
 642         int ret, start = 0;
 643         char b[BDEVNAME_SIZE];
 644
 645         q = bdev_get_queue(bdev);
 646         if (!q)
 647                 return -ENXIO;
 648
 649         mutex_lock(&bdev->bd_mutex);
 650
 651         switch (cmd) {
 652         case BLKTRACESETUP:
 653                 bdevname(bdev, b);
 654                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 655                 break;
 656 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 657         case BLKTRACESETUP32:
 658                 bdevname(bdev, b);
 659                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 660                 break;
 661 #endif
 662         case BLKTRACESTART:
 663                 start = 1;
 664         case BLKTRACESTOP:
 665                 ret = blk_trace_startstop(q, start);
 666                 break;
 667         case BLKTRACETEARDOWN:
 668                 ret = blk_trace_remove(q);
 669                 break;
 670         default:
 671                 ret = -ENOTTY;
 672                 break;
 673         }
 674
 675         mutex_unlock(&bdev->bd_mutex);
 676         return ret;
 677 }
 678
 679 /**
 680  * blk_trace_shutdown: - stop and cleanup trace structures
 681  * @q:    the request queue associated with the device
 682  *
 683  **/
 684 void blk_trace_shutdown(struct request_queue *q)
 685 {
 686         if (q->blk_trace) {
 687                 blk_trace_startstop(q, 0);
 688                 blk_trace_remove(q);
 689         }
 690 }
 691
 692 /*
 693  * blktrace probes
 694  */
 695
 696 /**
 697  * blk_add_trace_rq - Add a trace for a request oriented action
 698  * @q:          queue the io is for
 699  * @rq:         the source request
 700  * @nr_bytes:   number of completed bytes
 701  * @what:       the action
 702  *
 703  * Description:
 704  *     Records an action against a request. Will log the bio offset + size.
 705  *
 706  **/
 707 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 708                              unsigned int nr_bytes, u32 what)
 709 {
 710         struct blk_trace *bt = q->blk_trace;
 711
 712         if (likely(!bt))
 713                 return;
 714
 715         if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
 716                 what |= BLK_TC_ACT(BLK_TC_PC);
 717                 __blk_add_trace(bt, 0, nr_bytes, req_op(rq), rq->cmd_flags,
 718                                 what, rq->errors, rq->cmd_len, rq->cmd);
 719         } else  {
 720                 what |= BLK_TC_ACT(BLK_TC_FS);
 721                 __blk_add_trace(bt, blk_rq_pos(rq), nr_bytes, req_op(rq),
 722                                 rq->cmd_flags, what, rq->errors, 0, NULL);
 723         }
 724 }
 725
 726 static void blk_add_trace_rq_abort(void *ignore,
 727                                    struct request_queue *q, struct request *rq)
 728 {
 729         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_ABORT);
 730 }
 731
 732 static void blk_add_trace_rq_insert(void *ignore,
 733                                     struct request_queue *q, struct request *rq)
 734 {
 735         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_INSERT);
 736 }
 737
 738 static void blk_add_trace_rq_issue(void *ignore,
 739                                    struct request_queue *q, struct request *rq)
 740 {
 741         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_ISSUE);
 742 }
 743
 744 static void blk_add_trace_rq_requeue(void *ignore,
 745                                      struct request_queue *q,
 746                                      struct request *rq)
 747 {
 748         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_REQUEUE);
 749 }
 750
 751 static void blk_add_trace_rq_complete(void *ignore,
 752                                       struct request_queue *q,
 753                                       struct request *rq,
 754                                       unsigned int nr_bytes)
 755 {
 756         blk_add_trace_rq(q, rq, nr_bytes, BLK_TA_COMPLETE);
 757 }
 758
 759 /**
 760  * blk_add_trace_bio - Add a trace for a bio oriented action
 761  * @q:          queue the io is for
 762  * @bio:        the source bio
 763  * @what:       the action
 764  * @error:      error, if any
 765  *
 766  * Description:
 767  *     Records an action against a bio. Will log the bio offset + size.
 768  *
 769  **/
 770 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 771                               u32 what, int error)
 772 {
 773         struct blk_trace *bt = q->blk_trace;
 774
 775         if (likely(!bt))
 776                 return;
 777
 778         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
 779                         bio_op(bio), bio->bi_opf, what, error, 0, NULL);
 780 }
 781
 782 static void blk_add_trace_bio_bounce(void *ignore,
 783                                      struct request_queue *q, struct bio *bio)
 784 {
 785         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
 786 }
 787
 788 static void blk_add_trace_bio_complete(void *ignore,
 789                                        struct request_queue *q, struct bio *bio,
 790                                        int error)
 791 {
 792         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
 793 }
 794
 795 static void blk_add_trace_bio_backmerge(void *ignore,
 796                                         struct request_queue *q,
 797                                         struct request *rq,
 798                                         struct bio *bio)
 799 {
 800         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
 801 }
 802
 803 static void blk_add_trace_bio_frontmerge(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_FRONTMERGE, 0);
 809 }
 810
 811 static void blk_add_trace_bio_queue(void *ignore,
 812                                     struct request_queue *q, struct bio *bio)
 813 {
 814         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
 815 }
 816
 817 static void blk_add_trace_getrq(void *ignore,
 818                                 struct request_queue *q,
 819                                 struct bio *bio, int rw)
 820 {
 821         if (bio)
 822                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
 823         else {
 824                 struct blk_trace *bt = q->blk_trace;
 825
 826                 if (bt)
 827                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_GETRQ, 0, 0,
 828                                         NULL);
 829         }
 830 }
 831
 832
 833 static void blk_add_trace_sleeprq(void *ignore,
 834                                   struct request_queue *q,
 835                                   struct bio *bio, int rw)
 836 {
 837         if (bio)
 838                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
 839         else {
 840                 struct blk_trace *bt = q->blk_trace;
 841
 842                 if (bt)
 843                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_SLEEPRQ,
 844                                         0, 0, NULL);
 845         }
 846 }
 847
 848 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 849 {
 850         struct blk_trace *bt = q->blk_trace;
 851
 852         if (bt)
 853                 __blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
 854 }
 855
 856 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 857                                     unsigned int depth, bool explicit)
 858 {
 859         struct blk_trace *bt = q->blk_trace;
 860
 861         if (bt) {
 862                 __be64 rpdu = cpu_to_be64(depth);
 863                 u32 what;
 864
 865                 if (explicit)
 866                         what = BLK_TA_UNPLUG_IO;
 867                 else
 868                         what = BLK_TA_UNPLUG_TIMER;
 869
 870                 __blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu);
 871         }
 872 }
 873
 874 static void blk_add_trace_split(void *ignore,
 875                                 struct request_queue *q, struct bio *bio,
 876                                 unsigned int pdu)
 877 {
 878         struct blk_trace *bt = q->blk_trace;
 879
 880         if (bt) {
 881                 __be64 rpdu = cpu_to_be64(pdu);
 882
 883                 __blk_add_trace(bt, bio->bi_iter.bi_sector,
 884                                 bio->bi_iter.bi_size, bio_op(bio), bio->bi_opf,
 885                                 BLK_TA_SPLIT, bio->bi_error, sizeof(rpdu),
 886                                 &rpdu);
 887         }
 888 }
 889
 890 /**
 891  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
 892  * @ignore:     trace callback data parameter (not used)
 893  * @q:          queue the io is for
 894  * @bio:        the source bio
 895  * @dev:        target device
 896  * @from:       source sector
 897  *
 898  * Description:
 899  *     Device mapper or raid target sometimes need to split a bio because
 900  *     it spans a stripe (or similar). Add a trace for that action.
 901  *
 902  **/
 903 static void blk_add_trace_bio_remap(void *ignore,
 904                                     struct request_queue *q, struct bio *bio,
 905                                     dev_t dev, sector_t from)
 906 {
 907         struct blk_trace *bt = q->blk_trace;
 908         struct blk_io_trace_remap r;
 909
 910         if (likely(!bt))
 911                 return;
 912
 913         r.device_from = cpu_to_be32(dev);
 914         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
 915         r.sector_from = cpu_to_be64(from);
 916
 917         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
 918                         bio_op(bio), bio->bi_opf, BLK_TA_REMAP, bio->bi_error,
 919                         sizeof(r), &r);
 920 }
 921
 922 /**
 923  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
 924  * @ignore:     trace callback data parameter (not used)
 925  * @q:          queue the io is for
 926  * @rq:         the source request
 927  * @dev:        target device
 928  * @from:       source sector
 929  *
 930  * Description:
 931  *     Device mapper remaps request to other devices.
 932  *     Add a trace for that action.
 933  *
 934  **/
 935 static void blk_add_trace_rq_remap(void *ignore,
 936                                    struct request_queue *q,
 937                                    struct request *rq, dev_t dev,
 938                                    sector_t from)
 939 {
 940         struct blk_trace *bt = q->blk_trace;
 941         struct blk_io_trace_remap r;
 942
 943         if (likely(!bt))
 944                 return;
 945
 946         r.device_from = cpu_to_be32(dev);
 947         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
 948         r.sector_from = cpu_to_be64(from);
 949
 950         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 951                         rq_data_dir(rq), 0, BLK_TA_REMAP, !!rq->errors,
 952                         sizeof(r), &r);
 953 }
 954
 955 /**
 956  * blk_add_driver_data - Add binary message with driver-specific data
 957  * @q:          queue the io is for
 958  * @rq:         io request
 959  * @data:       driver-specific data
 960  * @len:        length of driver-specific data
 961  *
 962  * Description:
 963  *     Some drivers might want to write driver-specific data per request.
 964  *
 965  **/
 966 void blk_add_driver_data(struct request_queue *q,
 967                          struct request *rq,
 968                          void *data, size_t len)
 969 {
 970         struct blk_trace *bt = q->blk_trace;
 971
 972         if (likely(!bt))
 973                 return;
 974
 975         if (rq->cmd_type == REQ_TYPE_BLOCK_PC)
 976                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0, 0,
 977                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 978         else
 979                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0, 0,
 980                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 981 }
 982 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 983
 984 static void blk_register_tracepoints(void)
 985 {
 986         int ret;
 987
 988         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
 989         WARN_ON(ret);
 990         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
 991         WARN_ON(ret);
 992         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
 993         WARN_ON(ret);
 994         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
 995         WARN_ON(ret);
 996         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
 997         WARN_ON(ret);
 998         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
 999         WARN_ON(ret);
1000         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1001         WARN_ON(ret);
1002         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1003         WARN_ON(ret);
1004         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1005         WARN_ON(ret);
1006         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1007         WARN_ON(ret);
1008         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1009         WARN_ON(ret);
1010         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1011         WARN_ON(ret);
1012         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1013         WARN_ON(ret);
1014         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1015         WARN_ON(ret);
1016         ret = register_trace_block_split(blk_add_trace_split, NULL);
1017         WARN_ON(ret);
1018         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1019         WARN_ON(ret);
1020         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1021         WARN_ON(ret);
1022 }
1023
1024 static void blk_unregister_tracepoints(void)
1025 {
1026         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1027         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1028         unregister_trace_block_split(blk_add_trace_split, NULL);
1029         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1030         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1031         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1032         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1033         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1034         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1035         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1036         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1037         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1038         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1039         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1040         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1041         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1042         unregister_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
1043
1044         tracepoint_synchronize_unregister();
1045 }
1046
1047 /*
1048  * struct blk_io_tracer formatting routines
1049  */
1050
1051 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1052 {
1053         int i = 0;
1054         int tc = t->action >> BLK_TC_SHIFT;
1055
1056         if (t->action == BLK_TN_MESSAGE) {
1057                 rwbs[i++] = 'N';
1058                 goto out;
1059         }
1060
1061         if (tc & BLK_TC_FLUSH)
1062                 rwbs[i++] = 'F';
1063
1064         if (tc & BLK_TC_DISCARD)
1065                 rwbs[i++] = 'D';
1066         else if (tc & BLK_TC_WRITE)
1067                 rwbs[i++] = 'W';
1068         else if (t->bytes)
1069                 rwbs[i++] = 'R';
1070         else
1071                 rwbs[i++] = 'N';
1072
1073         if (tc & BLK_TC_FUA)
1074                 rwbs[i++] = 'F';
1075         if (tc & BLK_TC_AHEAD)
1076                 rwbs[i++] = 'A';
1077         if (tc & BLK_TC_SYNC)
1078                 rwbs[i++] = 'S';
1079         if (tc & BLK_TC_META)
1080                 rwbs[i++] = 'M';
1081 out:
1082         rwbs[i] = '\0';
1083 }
1084
1085 static inline
1086 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1087 {
1088         return (const struct blk_io_trace *)ent;
1089 }
1090
1091 static inline const void *pdu_start(const struct trace_entry *ent)
1092 {
1093         return te_blk_io_trace(ent) + 1;
1094 }
1095
1096 static inline u32 t_action(const struct trace_entry *ent)
1097 {
1098         return te_blk_io_trace(ent)->action;
1099 }
1100
1101 static inline u32 t_bytes(const struct trace_entry *ent)
1102 {
1103         return te_blk_io_trace(ent)->bytes;
1104 }
1105
1106 static inline u32 t_sec(const struct trace_entry *ent)
1107 {
1108         return te_blk_io_trace(ent)->bytes >> 9;
1109 }
1110
1111 static inline unsigned long long t_sector(const struct trace_entry *ent)
1112 {
1113         return te_blk_io_trace(ent)->sector;
1114 }
1115
1116 static inline __u16 t_error(const struct trace_entry *ent)
1117 {
1118         return te_blk_io_trace(ent)->error;
1119 }
1120
1121 static __u64 get_pdu_int(const struct trace_entry *ent)
1122 {
1123         const __u64 *val = pdu_start(ent);
1124         return be64_to_cpu(*val);
1125 }
1126
1127 static void get_pdu_remap(const struct trace_entry *ent,
1128                           struct blk_io_trace_remap *r)
1129 {
1130         const struct blk_io_trace_remap *__r = pdu_start(ent);
1131         __u64 sector_from = __r->sector_from;
1132
1133         r->device_from = be32_to_cpu(__r->device_from);
1134         r->device_to   = be32_to_cpu(__r->device_to);
1135         r->sector_from = be64_to_cpu(sector_from);
1136 }
1137
1138 typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1139
1140 static void blk_log_action_classic(struct trace_iterator *iter, const char *act)
1141 {
1142         char rwbs[RWBS_LEN];
1143         unsigned long long ts  = iter->ts;
1144         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1145         unsigned secs          = (unsigned long)ts;
1146         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1147
1148         fill_rwbs(rwbs, t);
1149
1150         trace_seq_printf(&iter->seq,
1151                          "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1152                          MAJOR(t->device), MINOR(t->device), iter->cpu,
1153                          secs, nsec_rem, iter->ent->pid, act, rwbs);
1154 }
1155
1156 static void blk_log_action(struct trace_iterator *iter, const char *act)
1157 {
1158         char rwbs[RWBS_LEN];
1159         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1160
1161         fill_rwbs(rwbs, t);
1162         trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1163                          MAJOR(t->device), MINOR(t->device), act, rwbs);
1164 }
1165
1166 static void blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1167 {
1168         const unsigned char *pdu_buf;
1169         int pdu_len;
1170         int i, end;
1171
1172         pdu_buf = pdu_start(ent);
1173         pdu_len = te_blk_io_trace(ent)->pdu_len;
1174
1175         if (!pdu_len)
1176                 return;
1177
1178         /* find the last zero that needs to be printed */
1179         for (end = pdu_len - 1; end >= 0; end--)
1180                 if (pdu_buf[end])
1181                         break;
1182         end++;
1183
1184         trace_seq_putc(s, '(');
1185
1186         for (i = 0; i < pdu_len; i++) {
1187
1188                 trace_seq_printf(s, "%s%02x",
1189                                  i == 0 ? "" : " ", pdu_buf[i]);
1190
1191                 /*
1192                  * stop when the rest is just zeroes and indicate so
1193                  * with a ".." appended
1194                  */
1195                 if (i == end && end != pdu_len - 1) {
1196                         trace_seq_puts(s, " ..) ");
1197                         return;
1198                 }
1199         }
1200
1201         trace_seq_puts(s, ") ");
1202 }
1203
1204 static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1205 {
1206         char cmd[TASK_COMM_LEN];
1207
1208         trace_find_cmdline(ent->pid, cmd);
1209
1210         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1211                 trace_seq_printf(s, "%u ", t_bytes(ent));
1212                 blk_log_dump_pdu(s, ent);
1213                 trace_seq_printf(s, "[%s]\n", cmd);
1214         } else {
1215                 if (t_sec(ent))
1216                         trace_seq_printf(s, "%llu + %u [%s]\n",
1217                                                 t_sector(ent), t_sec(ent), cmd);
1218                 else
1219                         trace_seq_printf(s, "[%s]\n", cmd);
1220         }
1221 }
1222
1223 static void blk_log_with_error(struct trace_seq *s,
1224                               const struct trace_entry *ent)
1225 {
1226         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1227                 blk_log_dump_pdu(s, ent);
1228                 trace_seq_printf(s, "[%d]\n", t_error(ent));
1229         } else {
1230                 if (t_sec(ent))
1231                         trace_seq_printf(s, "%llu + %u [%d]\n",
1232                                          t_sector(ent),
1233                                          t_sec(ent), t_error(ent));
1234                 else
1235                         trace_seq_printf(s, "%llu [%d]\n",
1236                                          t_sector(ent), t_error(ent));
1237         }
1238 }
1239
1240 static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1241 {
1242         struct blk_io_trace_remap r = { .device_from = 0, };
1243
1244         get_pdu_remap(ent, &r);
1245         trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1246                          t_sector(ent), t_sec(ent),
1247                          MAJOR(r.device_from), MINOR(r.device_from),
1248                          (unsigned long long)r.sector_from);
1249 }
1250
1251 static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1252 {
1253         char cmd[TASK_COMM_LEN];
1254
1255         trace_find_cmdline(ent->pid, cmd);
1256
1257         trace_seq_printf(s, "[%s]\n", cmd);
1258 }
1259
1260 static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1261 {
1262         char cmd[TASK_COMM_LEN];
1263
1264         trace_find_cmdline(ent->pid, cmd);
1265
1266         trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1267 }
1268
1269 static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1270 {
1271         char cmd[TASK_COMM_LEN];
1272
1273         trace_find_cmdline(ent->pid, cmd);
1274
1275         trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1276                          get_pdu_int(ent), cmd);
1277 }
1278
1279 static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1280 {
1281         const struct blk_io_trace *t = te_blk_io_trace(ent);
1282
1283         trace_seq_putmem(s, t + 1, t->pdu_len);
1284         trace_seq_putc(s, '\n');
1285 }
1286
1287 /*
1288  * struct tracer operations
1289  */
1290
1291 static void blk_tracer_print_header(struct seq_file *m)
1292 {
1293         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1294                 return;
1295         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1296                     "#  |     |     |           |   |   |\n");
1297 }
1298
1299 static void blk_tracer_start(struct trace_array *tr)
1300 {
1301         blk_tracer_enabled = true;
1302 }
1303
1304 static int blk_tracer_init(struct trace_array *tr)
1305 {
1306         blk_tr = tr;
1307         blk_tracer_start(tr);
1308         return 0;
1309 }
1310
1311 static void blk_tracer_stop(struct trace_array *tr)
1312 {
1313         blk_tracer_enabled = false;
1314 }
1315
1316 static void blk_tracer_reset(struct trace_array *tr)
1317 {
1318         blk_tracer_stop(tr);
1319 }
1320
1321 static const struct {
1322         const char *act[2];
1323         void       (*print)(struct trace_seq *s, const struct trace_entry *ent);
1324 } what2act[] = {
1325         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1326         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1327         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1328         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1329         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1330         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1331         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1332         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1333         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1334         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1335         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1336         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1337         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1338         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1339         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1340 };
1341
1342 static enum print_line_t print_one_line(struct trace_iterator *iter,
1343                                         bool classic)
1344 {
1345         struct trace_array *tr = iter->tr;
1346         struct trace_seq *s = &iter->seq;
1347         const struct blk_io_trace *t;
1348         u16 what;
1349         bool long_act;
1350         blk_log_action_t *log_action;
1351
1352         t          = te_blk_io_trace(iter->ent);
1353         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1354         long_act   = !!(tr->trace_flags & TRACE_ITER_VERBOSE);
1355         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1356
1357         if (t->action == BLK_TN_MESSAGE) {
1358                 log_action(iter, long_act ? "message" : "m");
1359                 blk_log_msg(s, iter->ent);
1360                 return trace_handle_return(s);
1361         }
1362
1363         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1364                 trace_seq_printf(s, "Unknown action %x\n", what);
1365         else {
1366                 log_action(iter, what2act[what].act[long_act]);
1367                 what2act[what].print(s, iter->ent);
1368         }
1369
1370         return trace_handle_return(s);
1371 }
1372
1373 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1374                                                int flags, struct trace_event *event)
1375 {
1376         return print_one_line(iter, false);
1377 }
1378
1379 static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1380 {
1381         struct trace_seq *s = &iter->seq;
1382         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1383         const int offset = offsetof(struct blk_io_trace, sector);
1384         struct blk_io_trace old = {
1385                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1386                 .time     = iter->ts,
1387         };
1388
1389         trace_seq_putmem(s, &old, offset);
1390         trace_seq_putmem(s, &t->sector,
1391                          sizeof(old) - offset + t->pdu_len);
1392 }
1393
1394 static enum print_line_t
1395 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1396                              struct trace_event *event)
1397 {
1398         blk_trace_synthesize_old_trace(iter);
1399
1400         return trace_handle_return(&iter->seq);
1401 }
1402
1403 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1404 {
1405         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1406                 return TRACE_TYPE_UNHANDLED;
1407
1408         return print_one_line(iter, true);
1409 }
1410
1411 static int
1412 blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1413 {
1414         /* don't output context-info for blk_classic output */
1415         if (bit == TRACE_BLK_OPT_CLASSIC) {
1416                 if (set)
1417                         tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1418                 else
1419                         tr->trace_flags |= TRACE_ITER_CONTEXT_INFO;
1420         }
1421         return 0;
1422 }
1423
1424 static struct tracer blk_tracer __read_mostly = {
1425         .name           = "blk",
1426         .init           = blk_tracer_init,
1427         .reset          = blk_tracer_reset,
1428         .start          = blk_tracer_start,
1429         .stop           = blk_tracer_stop,
1430         .print_header   = blk_tracer_print_header,
1431         .print_line     = blk_tracer_print_line,
1432         .flags          = &blk_tracer_flags,
1433         .set_flag       = blk_tracer_set_flag,
1434 };
1435
1436 static struct trace_event_functions trace_blk_event_funcs = {
1437         .trace          = blk_trace_event_print,
1438         .binary         = blk_trace_event_print_binary,
1439 };
1440
1441 static struct trace_event trace_blk_event = {
1442         .type           = TRACE_BLK,
1443         .funcs          = &trace_blk_event_funcs,
1444 };
1445
1446 static int __init init_blk_tracer(void)
1447 {
1448         if (!register_trace_event(&trace_blk_event)) {
1449                 pr_warn("Warning: could not register block events\n");
1450                 return 1;
1451         }
1452
1453         if (register_tracer(&blk_tracer) != 0) {
1454                 pr_warn("Warning: could not register the block tracer\n");
1455                 unregister_trace_event(&trace_blk_event);
1456                 return 1;
1457         }
1458
1459         return 0;
1460 }
1461
1462 device_initcall(init_blk_tracer);
1463
1464 static int blk_trace_remove_queue(struct request_queue *q)
1465 {
1466         struct blk_trace *bt;
1467
1468         bt = xchg(&q->blk_trace, NULL);
1469         if (bt == NULL)
1470                 return -EINVAL;
1471
1472         if (atomic_dec_and_test(&blk_probes_ref))
1473                 blk_unregister_tracepoints();
1474
1475         blk_trace_free(bt);
1476         return 0;
1477 }
1478
1479 /*
1480  * Setup everything required to start tracing
1481  */
1482 static int blk_trace_setup_queue(struct request_queue *q,
1483                                  struct block_device *bdev)
1484 {
1485         struct blk_trace *bt = NULL;
1486         int ret = -ENOMEM;
1487
1488         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1489         if (!bt)
1490                 return -ENOMEM;
1491
1492         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1493         if (!bt->msg_data)
1494                 goto free_bt;
1495
1496         bt->dev = bdev->bd_dev;
1497         bt->act_mask = (u16)-1;
1498
1499         blk_trace_setup_lba(bt, bdev);
1500
1501         ret = -EBUSY;
1502         if (cmpxchg(&q->blk_trace, NULL, bt))
1503                 goto free_bt;
1504
1505         if (atomic_inc_return(&blk_probes_ref) == 1)
1506                 blk_register_tracepoints();
1507         return 0;
1508
1509 free_bt:
1510         blk_trace_free(bt);
1511         return ret;
1512 }
1513
1514 /*
1515  * sysfs interface to enable and configure tracing
1516  */
1517
1518 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1519                                          struct device_attribute *attr,
1520                                          char *buf);
1521 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1522                                           struct device_attribute *attr,
1523                                           const char *buf, size_t count);
1524 #define BLK_TRACE_DEVICE_ATTR(_name) \
1525         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1526                     sysfs_blk_trace_attr_show, \
1527                     sysfs_blk_trace_attr_store)
1528
1529 static BLK_TRACE_DEVICE_ATTR(enable);
1530 static BLK_TRACE_DEVICE_ATTR(act_mask);
1531 static BLK_TRACE_DEVICE_ATTR(pid);
1532 static BLK_TRACE_DEVICE_ATTR(start_lba);
1533 static BLK_TRACE_DEVICE_ATTR(end_lba);
1534
1535 static struct attribute *blk_trace_attrs[] = {
1536         &dev_attr_enable.attr,
1537         &dev_attr_act_mask.attr,
1538         &dev_attr_pid.attr,
1539         &dev_attr_start_lba.attr,
1540         &dev_attr_end_lba.attr,
1541         NULL
1542 };
1543
1544 struct attribute_group blk_trace_attr_group = {
1545         .name  = "trace",
1546         .attrs = blk_trace_attrs,
1547 };
1548
1549 static const struct {
1550         int mask;
1551         const char *str;
1552 } mask_maps[] = {
1553         { BLK_TC_READ,          "read"          },
1554         { BLK_TC_WRITE,         "write"         },
1555         { BLK_TC_FLUSH,         "flush"         },
1556         { BLK_TC_SYNC,          "sync"          },
1557         { BLK_TC_QUEUE,         "queue"         },
1558         { BLK_TC_REQUEUE,       "requeue"       },
1559         { BLK_TC_ISSUE,         "issue"         },
1560         { BLK_TC_COMPLETE,      "complete"      },
1561         { BLK_TC_FS,            "fs"            },
1562         { BLK_TC_PC,            "pc"            },
1563         { BLK_TC_NOTIFY,        "notify"        },
1564         { BLK_TC_AHEAD,         "ahead"         },
1565         { BLK_TC_META,          "meta"          },
1566         { BLK_TC_DISCARD,       "discard"       },
1567         { BLK_TC_DRV_DATA,      "drv_data"      },
1568         { BLK_TC_FUA,           "fua"           },
1569 };
1570
1571 static int blk_trace_str2mask(const char *str)
1572 {
1573         int i;
1574         int mask = 0;
1575         char *buf, *s, *token;
1576
1577         buf = kstrdup(str, GFP_KERNEL);
1578         if (buf == NULL)
1579                 return -ENOMEM;
1580         s = strstrip(buf);
1581
1582         while (1) {
1583                 token = strsep(&s, ",");
1584                 if (token == NULL)
1585                         break;
1586
1587                 if (*token == '\0')
1588                         continue;
1589
1590                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1591                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1592                                 mask |= mask_maps[i].mask;
1593                                 break;
1594                         }
1595                 }
1596                 if (i == ARRAY_SIZE(mask_maps)) {
1597                         mask = -EINVAL;
1598                         break;
1599                 }
1600         }
1601         kfree(buf);
1602
1603         return mask;
1604 }
1605
1606 static ssize_t blk_trace_mask2str(char *buf, int mask)
1607 {
1608         int i;
1609         char *p = buf;
1610
1611         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1612                 if (mask & mask_maps[i].mask) {
1613                         p += sprintf(p, "%s%s",
1614                                     (p == buf) ? "" : ",", mask_maps[i].str);
1615                 }
1616         }
1617         *p++ = '\n';
1618
1619         return p - buf;
1620 }
1621
1622 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1623 {
1624         if (bdev->bd_disk == NULL)
1625                 return NULL;
1626
1627         return bdev_get_queue(bdev);
1628 }
1629
1630 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1631                                          struct device_attribute *attr,
1632                                          char *buf)
1633 {
1634         struct hd_struct *p = dev_to_part(dev);
1635         struct request_queue *q;
1636         struct block_device *bdev;
1637         ssize_t ret = -ENXIO;
1638
1639         bdev = bdget(part_devt(p));
1640         if (bdev == NULL)
1641                 goto out;
1642
1643         q = blk_trace_get_queue(bdev);
1644         if (q == NULL)
1645                 goto out_bdput;
1646
1647         mutex_lock(&bdev->bd_mutex);
1648
1649         if (attr == &dev_attr_enable) {
1650                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1651                 goto out_unlock_bdev;
1652         }
1653
1654         if (q->blk_trace == NULL)
1655                 ret = sprintf(buf, "disabled\n");
1656         else if (attr == &dev_attr_act_mask)
1657                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1658         else if (attr == &dev_attr_pid)
1659                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1660         else if (attr == &dev_attr_start_lba)
1661                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1662         else if (attr == &dev_attr_end_lba)
1663                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1664
1665 out_unlock_bdev:
1666         mutex_unlock(&bdev->bd_mutex);
1667 out_bdput:
1668         bdput(bdev);
1669 out:
1670         return ret;
1671 }
1672
1673 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1674                                           struct device_attribute *attr,
1675                                           const char *buf, size_t count)
1676 {
1677         struct block_device *bdev;
1678         struct request_queue *q;
1679         struct hd_struct *p;
1680         u64 value;
1681         ssize_t ret = -EINVAL;
1682
1683         if (count == 0)
1684                 goto out;
1685
1686         if (attr == &dev_attr_act_mask) {
1687                 if (sscanf(buf, "%llx", &value) != 1) {
1688                         /* Assume it is a list of trace category names */
1689                         ret = blk_trace_str2mask(buf);
1690                         if (ret < 0)
1691                                 goto out;
1692                         value = ret;
1693                 }
1694         } else if (sscanf(buf, "%llu", &value) != 1)
1695                 goto out;
1696
1697         ret = -ENXIO;
1698
1699         p = dev_to_part(dev);
1700         bdev = bdget(part_devt(p));
1701         if (bdev == NULL)
1702                 goto out;
1703
1704         q = blk_trace_get_queue(bdev);
1705         if (q == NULL)
1706                 goto out_bdput;
1707
1708         mutex_lock(&bdev->bd_mutex);
1709
1710         if (attr == &dev_attr_enable) {
1711                 if (value)
1712                         ret = blk_trace_setup_queue(q, bdev);
1713                 else
1714                         ret = blk_trace_remove_queue(q);
1715                 goto out_unlock_bdev;
1716         }
1717
1718         ret = 0;
1719         if (q->blk_trace == NULL)
1720                 ret = blk_trace_setup_queue(q, bdev);
1721
1722         if (ret == 0) {
1723                 if (attr == &dev_attr_act_mask)
1724                         q->blk_trace->act_mask = value;
1725                 else if (attr == &dev_attr_pid)
1726                         q->blk_trace->pid = value;
1727                 else if (attr == &dev_attr_start_lba)
1728                         q->blk_trace->start_lba = value;
1729                 else if (attr == &dev_attr_end_lba)
1730                         q->blk_trace->end_lba = value;
1731         }
1732
1733 out_unlock_bdev:
1734         mutex_unlock(&bdev->bd_mutex);
1735 out_bdput:
1736         bdput(bdev);
1737 out:
1738         return ret ? ret : count;
1739 }
1740
1741 int blk_trace_init_sysfs(struct device *dev)
1742 {
1743         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1744 }
1745
1746 void blk_trace_remove_sysfs(struct device *dev)
1747 {
1748         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1749 }
1750
1751 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1752
1753 #ifdef CONFIG_EVENT_TRACING
1754
1755 void blk_dump_cmd(char *buf, struct request *rq)
1756 {
1757         int i, end;
1758         int len = rq->cmd_len;
1759         unsigned char *cmd = rq->cmd;
1760
1761         if (rq->cmd_type != REQ_TYPE_BLOCK_PC) {
1762                 buf[0] = '\0';
1763                 return;
1764         }
1765
1766         for (end = len - 1; end >= 0; end--)
1767                 if (cmd[end])
1768                         break;
1769         end++;
1770
1771         for (i = 0; i < len; i++) {
1772                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1773                 if (i == end && end != len - 1) {
1774                         sprintf(buf, " ..");
1775                         break;
1776                 }
1777         }
1778 }
1779
1780 void blk_fill_rwbs(char *rwbs, int op, u32 rw, int bytes)
1781 {
1782         int i = 0;
1783
1784         if (rw & REQ_PREFLUSH)
1785                 rwbs[i++] = 'F';
1786
1787         switch (op) {
1788         case REQ_OP_WRITE:
1789         case REQ_OP_WRITE_SAME:
1790                 rwbs[i++] = 'W';
1791                 break;
1792         case REQ_OP_DISCARD:
1793                 rwbs[i++] = 'D';
1794                 break;
1795         case REQ_OP_SECURE_ERASE:
1796                 rwbs[i++] = 'D';
1797                 rwbs[i++] = 'E';
1798                 break;
1799         case REQ_OP_FLUSH:
1800                 rwbs[i++] = 'F';
1801                 break;
1802         case REQ_OP_READ:
1803                 rwbs[i++] = 'R';
1804                 break;
1805         default:
1806                 rwbs[i++] = 'N';
1807         }
1808
1809         if (rw & REQ_FUA)
1810                 rwbs[i++] = 'F';
1811         if (rw & REQ_RAHEAD)
1812                 rwbs[i++] = 'A';
1813         if (rw & REQ_SYNC)
1814                 rwbs[i++] = 'S';
1815         if (rw & REQ_META)
1816                 rwbs[i++] = 'M';
1817
1818         rwbs[i] = '\0';
1819 }
1820 EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1821
1822 #endif /* CONFIG_EVENT_TRACING */
1823