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
  30 #include <trace/events/block.h>
  31
  32 #include "trace_output.h"
  33
  34 #ifdef CONFIG_BLK_DEV_IO_TRACE
  35
  36 static unsigned int blktrace_seq __read_mostly = 1;
  37
  38 static struct trace_array *blk_tr;
  39 static bool blk_tracer_enabled __read_mostly;
  40
  41 /* Select an alternative, minimalistic output than the original one */
  42 #define TRACE_BLK_OPT_CLASSIC   0x1
  43
  44 static struct tracer_opt blk_tracer_opts[] = {
  45         /* Default disable the minimalistic output */
  46         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
  47         { }
  48 };
  49
  50 static struct tracer_flags blk_tracer_flags = {
  51         .val  = 0,
  52         .opts = blk_tracer_opts,
  53 };
  54
  55 /* Global reference count of probes */
  56 static atomic_t blk_probes_ref = ATOMIC_INIT(0);
  57
  58 static void blk_register_tracepoints(void);
  59 static void blk_unregister_tracepoints(void);
  60
  61 /*
  62  * Send out a notify message.
  63  */
  64 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
  65                        const void *data, size_t len)
  66 {
  67         struct blk_io_trace *t;
  68         struct ring_buffer_event *event = NULL;
  69         struct ring_buffer *buffer = NULL;
  70         int pc = 0;
  71         int cpu = smp_processor_id();
  72         bool blk_tracer = blk_tracer_enabled;
  73
  74         if (blk_tracer) {
  75                 buffer = blk_tr->trace_buffer.buffer;
  76                 pc = preempt_count();
  77                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
  78                                                   sizeof(*t) + len,
  79                                                   0, pc);
  80                 if (!event)
  81                         return;
  82                 t = ring_buffer_event_data(event);
  83                 goto record_it;
  84         }
  85
  86         if (!bt->rchan)
  87                 return;
  88
  89         t = relay_reserve(bt->rchan, sizeof(*t) + len);
  90         if (t) {
  91                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
  92                 t->time = ktime_to_ns(ktime_get());
  93 record_it:
  94                 t->device = bt->dev;
  95                 t->action = action;
  96                 t->pid = pid;
  97                 t->cpu = cpu;
  98                 t->pdu_len = len;
  99                 memcpy((void *) t + sizeof(*t), data, len);
 100
 101                 if (blk_tracer)
 102                         trace_buffer_unlock_commit(buffer, event, 0, pc);
 103         }
 104 }
 105
 106 /*
 107  * Send out a notify for this process, if we haven't done so since a trace
 108  * started
 109  */
 110 static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
 111 {
 112         tsk->btrace_seq = blktrace_seq;
 113         trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));
 114 }
 115
 116 static void trace_note_time(struct blk_trace *bt)
 117 {
 118         struct timespec now;
 119         unsigned long flags;
 120         u32 words[2];
 121
 122         getnstimeofday(&now);
 123         words[0] = now.tv_sec;
 124         words[1] = now.tv_nsec;
 125
 126         local_irq_save(flags);
 127         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
 128         local_irq_restore(flags);
 129 }
 130
 131 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 132 {
 133         int n;
 134         va_list args;
 135         unsigned long flags;
 136         char *buf;
 137
 138         if (unlikely(bt->trace_state != Blktrace_running &&
 139                      !blk_tracer_enabled))
 140                 return;
 141
 142         /*
 143          * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
 144          * message to the trace.
 145          */
 146         if (!(bt->act_mask & BLK_TC_NOTIFY))
 147                 return;
 148
 149         local_irq_save(flags);
 150         buf = this_cpu_ptr(bt->msg_data);
 151         va_start(args, fmt);
 152         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 153         va_end(args);
 154
 155         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
 156         local_irq_restore(flags);
 157 }
 158 EXPORT_SYMBOL_GPL(__trace_note_message);
 159
 160 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
 161                          pid_t pid)
 162 {
 163         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
 164                 return 1;
 165         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
 166                 return 1;
 167         if (bt->pid && pid != bt->pid)
 168                 return 1;
 169
 170         return 0;
 171 }
 172
 173 /*
 174  * Data direction bit lookup
 175  */
 176 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
 177                                  BLK_TC_ACT(BLK_TC_WRITE) };
 178
 179 #define BLK_TC_RAHEAD           BLK_TC_AHEAD
 180
 181 /* The ilog2() calls fall out because they're constant */
 182 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
 183           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
 184
 185 /*
 186  * The worker for the various blk_add_trace*() types. Fills out a
 187  * blk_io_trace structure and places it in a per-cpu subbuffer.
 188  */
 189 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 190                      int rw, u32 what, int error, int pdu_len, void *pdu_data)
 191 {
 192         struct task_struct *tsk = current;
 193         struct ring_buffer_event *event = NULL;
 194         struct ring_buffer *buffer = NULL;
 195         struct blk_io_trace *t;
 196         unsigned long flags = 0;
 197         unsigned long *sequence;
 198         pid_t pid;
 199         int cpu, pc = 0;
 200         bool blk_tracer = blk_tracer_enabled;
 201
 202         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
 203                 return;
 204
 205         what |= ddir_act[rw & WRITE];
 206         what |= MASK_TC_BIT(rw, SYNC);
 207         what |= MASK_TC_BIT(rw, RAHEAD);
 208         what |= MASK_TC_BIT(rw, META);
 209         what |= MASK_TC_BIT(rw, DISCARD);
 210         what |= MASK_TC_BIT(rw, FLUSH);
 211         what |= MASK_TC_BIT(rw, FUA);
 212
 213         pid = tsk->pid;
 214         if (act_log_check(bt, what, sector, pid))
 215                 return;
 216         cpu = raw_smp_processor_id();
 217
 218         if (blk_tracer) {
 219                 tracing_record_cmdline(current);
 220
 221                 buffer = blk_tr->trace_buffer.buffer;
 222                 pc = preempt_count();
 223                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 224                                                   sizeof(*t) + pdu_len,
 225                                                   0, pc);
 226                 if (!event)
 227                         return;
 228                 t = ring_buffer_event_data(event);
 229                 goto record_it;
 230         }
 231
 232         /*
 233          * A word about the locking here - we disable interrupts to reserve
 234          * some space in the relay per-cpu buffer, to prevent an irq
 235          * from coming in and stepping on our toes.
 236          */
 237         local_irq_save(flags);
 238
 239         if (unlikely(tsk->btrace_seq != blktrace_seq))
 240                 trace_note_tsk(bt, tsk);
 241
 242         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
 243         if (t) {
 244                 sequence = per_cpu_ptr(bt->sequence, cpu);
 245
 246                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 247                 t->sequence = ++(*sequence);
 248                 t->time = ktime_to_ns(ktime_get());
 249 record_it:
 250                 /*
 251                  * These two are not needed in ftrace as they are in the
 252                  * generic trace_entry, filled by tracing_generic_entry_update,
 253                  * but for the trace_event->bin() synthesizer benefit we do it
 254                  * here too.
 255                  */
 256                 t->cpu = cpu;
 257                 t->pid = pid;
 258
 259                 t->sector = sector;
 260                 t->bytes = bytes;
 261                 t->action = what;
 262                 t->device = bt->dev;
 263                 t->error = error;
 264                 t->pdu_len = pdu_len;
 265
 266                 if (pdu_len)
 267                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
 268
 269                 if (blk_tracer) {
 270                         trace_buffer_unlock_commit(buffer, event, 0, pc);
 271                         return;
 272                 }
 273         }
 274
 275         local_irq_restore(flags);
 276 }
 277
 278 static struct dentry *blk_tree_root;
 279 static DEFINE_MUTEX(blk_tree_mutex);
 280
 281 static void blk_trace_free(struct blk_trace *bt)
 282 {
 283         debugfs_remove(bt->msg_file);
 284         debugfs_remove(bt->dropped_file);
 285         relay_close(bt->rchan);
 286         debugfs_remove(bt->dir);
 287         free_percpu(bt->sequence);
 288         free_percpu(bt->msg_data);
 289         kfree(bt);
 290 }
 291
 292 static void blk_trace_cleanup(struct blk_trace *bt)
 293 {
 294         blk_trace_free(bt);
 295         if (atomic_dec_and_test(&blk_probes_ref))
 296                 blk_unregister_tracepoints();
 297 }
 298
 299 int blk_trace_remove(struct request_queue *q)
 300 {
 301         struct blk_trace *bt;
 302
 303         bt = xchg(&q->blk_trace, NULL);
 304         if (!bt)
 305                 return -EINVAL;
 306
 307         if (bt->trace_state != Blktrace_running)
 308                 blk_trace_cleanup(bt);
 309
 310         return 0;
 311 }
 312 EXPORT_SYMBOL_GPL(blk_trace_remove);
 313
 314 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
 315                                 size_t count, loff_t *ppos)
 316 {
 317         struct blk_trace *bt = filp->private_data;
 318         char buf[16];
 319
 320         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
 321
 322         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 323 }
 324
 325 static const struct file_operations blk_dropped_fops = {
 326         .owner =        THIS_MODULE,
 327         .open =         simple_open,
 328         .read =         blk_dropped_read,
 329         .llseek =       default_llseek,
 330 };
 331
 332 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 333                                 size_t count, loff_t *ppos)
 334 {
 335         char *msg;
 336         struct blk_trace *bt;
 337
 338         if (count >= BLK_TN_MAX_MSG)
 339                 return -EINVAL;
 340
 341         msg = kmalloc(count + 1, GFP_KERNEL);
 342         if (msg == NULL)
 343                 return -ENOMEM;
 344
 345         if (copy_from_user(msg, buffer, count)) {
 346                 kfree(msg);
 347                 return -EFAULT;
 348         }
 349
 350         msg[count] = '\0';
 351         bt = filp->private_data;
 352         __trace_note_message(bt, "%s", msg);
 353         kfree(msg);
 354
 355         return count;
 356 }
 357
 358 static const struct file_operations blk_msg_fops = {
 359         .owner =        THIS_MODULE,
 360         .open =         simple_open,
 361         .write =        blk_msg_write,
 362         .llseek =       noop_llseek,
 363 };
 364
 365 /*
 366  * Keep track of how many times we encountered a full subbuffer, to aid
 367  * the user space app in telling how many lost events there were.
 368  */
 369 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
 370                                      void *prev_subbuf, size_t prev_padding)
 371 {
 372         struct blk_trace *bt;
 373
 374         if (!relay_buf_full(buf))
 375                 return 1;
 376
 377         bt = buf->chan->private_data;
 378         atomic_inc(&bt->dropped);
 379         return 0;
 380 }
 381
 382 static int blk_remove_buf_file_callback(struct dentry *dentry)
 383 {
 384         debugfs_remove(dentry);
 385
 386         return 0;
 387 }
 388
 389 static struct dentry *blk_create_buf_file_callback(const char *filename,
 390                                                    struct dentry *parent,
 391                                                    umode_t mode,
 392                                                    struct rchan_buf *buf,
 393                                                    int *is_global)
 394 {
 395         return debugfs_create_file(filename, mode, parent, buf,
 396                                         &relay_file_operations);
 397 }
 398
 399 static struct rchan_callbacks blk_relay_callbacks = {
 400         .subbuf_start           = blk_subbuf_start_callback,
 401         .create_buf_file        = blk_create_buf_file_callback,
 402         .remove_buf_file        = blk_remove_buf_file_callback,
 403 };
 404
 405 static void blk_trace_setup_lba(struct blk_trace *bt,
 406                                 struct block_device *bdev)
 407 {
 408         struct hd_struct *part = NULL;
 409
 410         if (bdev)
 411                 part = bdev->bd_part;
 412
 413         if (part) {
 414                 bt->start_lba = part->start_sect;
 415                 bt->end_lba = part->start_sect + part->nr_sects;
 416         } else {
 417                 bt->start_lba = 0;
 418                 bt->end_lba = -1ULL;
 419         }
 420 }
 421
 422 /*
 423  * Setup everything required to start tracing
 424  */
 425 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 426                        struct block_device *bdev,
 427                        struct blk_user_trace_setup *buts)
 428 {
 429         struct blk_trace *old_bt, *bt = NULL;
 430         struct dentry *dir = NULL;
 431         int ret, i;
 432
 433         if (!buts->buf_size || !buts->buf_nr)
 434                 return -EINVAL;
 435
 436         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 437         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 438
 439         /*
 440          * some device names have larger paths - convert the slashes
 441          * to underscores for this to work as expected
 442          */
 443         for (i = 0; i < strlen(buts->name); i++)
 444                 if (buts->name[i] == '/')
 445                         buts->name[i] = '_';
 446
 447         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 448         if (!bt)
 449                 return -ENOMEM;
 450
 451         ret = -ENOMEM;
 452         bt->sequence = alloc_percpu(unsigned long);
 453         if (!bt->sequence)
 454                 goto err;
 455
 456         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 457         if (!bt->msg_data)
 458                 goto err;
 459
 460         ret = -ENOENT;
 461
 462         mutex_lock(&blk_tree_mutex);
 463         if (!blk_tree_root) {
 464                 blk_tree_root = debugfs_create_dir("block", NULL);
 465                 if (!blk_tree_root) {
 466                         mutex_unlock(&blk_tree_mutex);
 467                         goto err;
 468                 }
 469         }
 470         mutex_unlock(&blk_tree_mutex);
 471
 472         dir = debugfs_create_dir(buts->name, blk_tree_root);
 473
 474         if (!dir)
 475                 goto err;
 476
 477         bt->dir = dir;
 478         bt->dev = dev;
 479         atomic_set(&bt->dropped, 0);
 480
 481         ret = -EIO;
 482         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 483                                                &blk_dropped_fops);
 484         if (!bt->dropped_file)
 485                 goto err;
 486
 487         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 488         if (!bt->msg_file)
 489                 goto err;
 490
 491         bt->rchan = relay_open("trace", dir, buts->buf_size,
 492                                 buts->buf_nr, &blk_relay_callbacks, bt);
 493         if (!bt->rchan)
 494                 goto err;
 495
 496         bt->act_mask = buts->act_mask;
 497         if (!bt->act_mask)
 498                 bt->act_mask = (u16) -1;
 499
 500         blk_trace_setup_lba(bt, bdev);
 501
 502         /* overwrite with user settings */
 503         if (buts->start_lba)
 504                 bt->start_lba = buts->start_lba;
 505         if (buts->end_lba)
 506                 bt->end_lba = buts->end_lba;
 507
 508         bt->pid = buts->pid;
 509         bt->trace_state = Blktrace_setup;
 510
 511         ret = -EBUSY;
 512         old_bt = xchg(&q->blk_trace, bt);
 513         if (old_bt) {
 514                 (void) xchg(&q->blk_trace, old_bt);
 515                 goto err;
 516         }
 517
 518         if (atomic_inc_return(&blk_probes_ref) == 1)
 519                 blk_register_tracepoints();
 520
 521         return 0;
 522 err:
 523         blk_trace_free(bt);
 524         return ret;
 525 }
 526
 527 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 528                     struct block_device *bdev,
 529                     char __user *arg)
 530 {
 531         struct blk_user_trace_setup buts;
 532         int ret;
 533
 534         ret = copy_from_user(&buts, arg, sizeof(buts));
 535         if (ret)
 536                 return -EFAULT;
 537
 538         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 539         if (ret)
 540                 return ret;
 541
 542         if (copy_to_user(arg, &buts, sizeof(buts))) {
 543                 blk_trace_remove(q);
 544                 return -EFAULT;
 545         }
 546         return 0;
 547 }
 548 EXPORT_SYMBOL_GPL(blk_trace_setup);
 549
 550 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 551 static int compat_blk_trace_setup(struct request_queue *q, char *name,
 552                                   dev_t dev, struct block_device *bdev,
 553                                   char __user *arg)
 554 {
 555         struct blk_user_trace_setup buts;
 556         struct compat_blk_user_trace_setup cbuts;
 557         int ret;
 558
 559         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
 560                 return -EFAULT;
 561
 562         buts = (struct blk_user_trace_setup) {
 563                 .act_mask = cbuts.act_mask,
 564                 .buf_size = cbuts.buf_size,
 565                 .buf_nr = cbuts.buf_nr,
 566                 .start_lba = cbuts.start_lba,
 567                 .end_lba = cbuts.end_lba,
 568                 .pid = cbuts.pid,
 569         };
 570         memcpy(&buts.name, &cbuts.name, 32);
 571
 572         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 573         if (ret)
 574                 return ret;
 575
 576         if (copy_to_user(arg, &buts.name, 32)) {
 577                 blk_trace_remove(q);
 578                 return -EFAULT;
 579         }
 580
 581         return 0;
 582 }
 583 #endif
 584
 585 int blk_trace_startstop(struct request_queue *q, int start)
 586 {
 587         int ret;
 588         struct blk_trace *bt = q->blk_trace;
 589
 590         if (bt == NULL)
 591                 return -EINVAL;
 592
 593         /*
 594          * For starting a trace, we can transition from a setup or stopped
 595          * trace. For stopping a trace, the state must be running
 596          */
 597         ret = -EINVAL;
 598         if (start) {
 599                 if (bt->trace_state == Blktrace_setup ||
 600                     bt->trace_state == Blktrace_stopped) {
 601                         blktrace_seq++;
 602                         smp_mb();
 603                         bt->trace_state = Blktrace_running;
 604
 605                         trace_note_time(bt);
 606                         ret = 0;
 607                 }
 608         } else {
 609                 if (bt->trace_state == Blktrace_running) {
 610                         bt->trace_state = Blktrace_stopped;
 611                         relay_flush(bt->rchan);
 612                         ret = 0;
 613                 }
 614         }
 615
 616         return ret;
 617 }
 618 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 619
 620 /**
 621  * blk_trace_ioctl: - handle the ioctls associated with tracing
 622  * @bdev:       the block device
 623  * @cmd:        the ioctl cmd
 624  * @arg:        the argument data, if any
 625  *
 626  **/
 627 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 628 {
 629         struct request_queue *q;
 630         int ret, start = 0;
 631         char b[BDEVNAME_SIZE];
 632
 633         q = bdev_get_queue(bdev);
 634         if (!q)
 635                 return -ENXIO;
 636
 637         mutex_lock(&bdev->bd_mutex);
 638
 639         switch (cmd) {
 640         case BLKTRACESETUP:
 641                 bdevname(bdev, b);
 642                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 643                 break;
 644 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 645         case BLKTRACESETUP32:
 646                 bdevname(bdev, b);
 647                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 648                 break;
 649 #endif
 650         case BLKTRACESTART:
 651                 start = 1;
 652         case BLKTRACESTOP:
 653                 ret = blk_trace_startstop(q, start);
 654                 break;
 655         case BLKTRACETEARDOWN:
 656                 ret = blk_trace_remove(q);
 657                 break;
 658         default:
 659                 ret = -ENOTTY;
 660                 break;
 661         }
 662
 663         mutex_unlock(&bdev->bd_mutex);
 664         return ret;
 665 }
 666
 667 /**
 668  * blk_trace_shutdown: - stop and cleanup trace structures
 669  * @q:    the request queue associated with the device
 670  *
 671  **/
 672 void blk_trace_shutdown(struct request_queue *q)
 673 {
 674         if (q->blk_trace) {
 675                 blk_trace_startstop(q, 0);
 676                 blk_trace_remove(q);
 677         }
 678 }
 679
 680 /*
 681  * blktrace probes
 682  */
 683
 684 /**
 685  * blk_add_trace_rq - Add a trace for a request oriented action
 686  * @q:          queue the io is for
 687  * @rq:         the source request
 688  * @what:       the action
 689  *
 690  * Description:
 691  *     Records an action against a request. Will log the bio offset + size.
 692  *
 693  **/
 694 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 695                              u32 what)
 696 {
 697         struct blk_trace *bt = q->blk_trace;
 698
 699         if (likely(!bt))
 700                 return;
 701
 702         if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
 703                 what |= BLK_TC_ACT(BLK_TC_PC);
 704                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), rq->cmd_flags,
 705                                 what, rq->errors, rq->cmd_len, rq->cmd);
 706         } else  {
 707                 what |= BLK_TC_ACT(BLK_TC_FS);
 708                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 709                                 rq->cmd_flags, what, rq->errors, 0, NULL);
 710         }
 711 }
 712
 713 static void blk_add_trace_rq_abort(void *ignore,
 714                                    struct request_queue *q, struct request *rq)
 715 {
 716         blk_add_trace_rq(q, rq, BLK_TA_ABORT);
 717 }
 718
 719 static void blk_add_trace_rq_insert(void *ignore,
 720                                     struct request_queue *q, struct request *rq)
 721 {
 722         blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 723 }
 724
 725 static void blk_add_trace_rq_issue(void *ignore,
 726                                    struct request_queue *q, struct request *rq)
 727 {
 728         blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
 729 }
 730
 731 static void blk_add_trace_rq_requeue(void *ignore,
 732                                      struct request_queue *q,
 733                                      struct request *rq)
 734 {
 735         blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
 736 }
 737
 738 static void blk_add_trace_rq_complete(void *ignore,
 739                                       struct request_queue *q,
 740                                       struct request *rq)
 741 {
 742         blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
 743 }
 744
 745 /**
 746  * blk_add_trace_bio - Add a trace for a bio oriented action
 747  * @q:          queue the io is for
 748  * @bio:        the source bio
 749  * @what:       the action
 750  * @error:      error, if any
 751  *
 752  * Description:
 753  *     Records an action against a bio. Will log the bio offset + size.
 754  *
 755  **/
 756 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 757                               u32 what, int error)
 758 {
 759         struct blk_trace *bt = q->blk_trace;
 760
 761         if (likely(!bt))
 762                 return;
 763
 764         if (!error && !bio_flagged(bio, BIO_UPTODATE))
 765                 error = EIO;
 766
 767         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
 768                         error, 0, NULL);
 769 }
 770
 771 static void blk_add_trace_bio_bounce(void *ignore,
 772                                      struct request_queue *q, struct bio *bio)
 773 {
 774         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
 775 }
 776
 777 static void blk_add_trace_bio_complete(void *ignore,
 778                                        struct request_queue *q, struct bio *bio,
 779                                        int error)
 780 {
 781         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
 782 }
 783
 784 static void blk_add_trace_bio_backmerge(void *ignore,
 785                                         struct request_queue *q,
 786                                         struct request *rq,
 787                                         struct bio *bio)
 788 {
 789         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
 790 }
 791
 792 static void blk_add_trace_bio_frontmerge(void *ignore,
 793                                          struct request_queue *q,
 794                                          struct request *rq,
 795                                          struct bio *bio)
 796 {
 797         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
 798 }
 799
 800 static void blk_add_trace_bio_queue(void *ignore,
 801                                     struct request_queue *q, struct bio *bio)
 802 {
 803         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
 804 }
 805
 806 static void blk_add_trace_getrq(void *ignore,
 807                                 struct request_queue *q,
 808                                 struct bio *bio, int rw)
 809 {
 810         if (bio)
 811                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
 812         else {
 813                 struct blk_trace *bt = q->blk_trace;
 814
 815                 if (bt)
 816                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
 817         }
 818 }
 819
 820
 821 static void blk_add_trace_sleeprq(void *ignore,
 822                                   struct request_queue *q,
 823                                   struct bio *bio, int rw)
 824 {
 825         if (bio)
 826                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
 827         else {
 828                 struct blk_trace *bt = q->blk_trace;
 829
 830                 if (bt)
 831                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
 832                                         0, 0, NULL);
 833         }
 834 }
 835
 836 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 837 {
 838         struct blk_trace *bt = q->blk_trace;
 839
 840         if (bt)
 841                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
 842 }
 843
 844 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 845                                     unsigned int depth, bool explicit)
 846 {
 847         struct blk_trace *bt = q->blk_trace;
 848
 849         if (bt) {
 850                 __be64 rpdu = cpu_to_be64(depth);
 851                 u32 what;
 852
 853                 if (explicit)
 854                         what = BLK_TA_UNPLUG_IO;
 855                 else
 856                         what = BLK_TA_UNPLUG_TIMER;
 857
 858                 __blk_add_trace(bt, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu);
 859         }
 860 }
 861
 862 static void blk_add_trace_split(void *ignore,
 863                                 struct request_queue *q, struct bio *bio,
 864                                 unsigned int pdu)
 865 {
 866         struct blk_trace *bt = q->blk_trace;
 867
 868         if (bt) {
 869                 __be64 rpdu = cpu_to_be64(pdu);
 870
 871                 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 872                                 BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
 873                                 sizeof(rpdu), &rpdu);
 874         }
 875 }
 876
 877 /**
 878  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
 879  * @ignore:     trace callback data parameter (not used)
 880  * @q:          queue the io is for
 881  * @bio:        the source bio
 882  * @dev:        target device
 883  * @from:       source sector
 884  *
 885  * Description:
 886  *     Device mapper or raid target sometimes need to split a bio because
 887  *     it spans a stripe (or similar). Add a trace for that action.
 888  *
 889  **/
 890 static void blk_add_trace_bio_remap(void *ignore,
 891                                     struct request_queue *q, struct bio *bio,
 892                                     dev_t dev, sector_t from)
 893 {
 894         struct blk_trace *bt = q->blk_trace;
 895         struct blk_io_trace_remap r;
 896
 897         if (likely(!bt))
 898                 return;
 899
 900         r.device_from = cpu_to_be32(dev);
 901         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
 902         r.sector_from = cpu_to_be64(from);
 903
 904         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 905                         BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE),
 906                         sizeof(r), &r);
 907 }
 908
 909 /**
 910  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
 911  * @ignore:     trace callback data parameter (not used)
 912  * @q:          queue the io is for
 913  * @rq:         the source request
 914  * @dev:        target device
 915  * @from:       source sector
 916  *
 917  * Description:
 918  *     Device mapper remaps request to other devices.
 919  *     Add a trace for that action.
 920  *
 921  **/
 922 static void blk_add_trace_rq_remap(void *ignore,
 923                                    struct request_queue *q,
 924                                    struct request *rq, dev_t dev,
 925                                    sector_t from)
 926 {
 927         struct blk_trace *bt = q->blk_trace;
 928         struct blk_io_trace_remap r;
 929
 930         if (likely(!bt))
 931                 return;
 932
 933         r.device_from = cpu_to_be32(dev);
 934         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
 935         r.sector_from = cpu_to_be64(from);
 936
 937         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 938                         rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
 939                         sizeof(r), &r);
 940 }
 941
 942 /**
 943  * blk_add_driver_data - Add binary message with driver-specific data
 944  * @q:          queue the io is for
 945  * @rq:         io request
 946  * @data:       driver-specific data
 947  * @len:        length of driver-specific data
 948  *
 949  * Description:
 950  *     Some drivers might want to write driver-specific data per request.
 951  *
 952  **/
 953 void blk_add_driver_data(struct request_queue *q,
 954                          struct request *rq,
 955                          void *data, size_t len)
 956 {
 957         struct blk_trace *bt = q->blk_trace;
 958
 959         if (likely(!bt))
 960                 return;
 961
 962         if (rq->cmd_type == REQ_TYPE_BLOCK_PC)
 963                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
 964                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 965         else
 966                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
 967                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 968 }
 969 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 970
 971 static void blk_register_tracepoints(void)
 972 {
 973         int ret;
 974
 975         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
 976         WARN_ON(ret);
 977         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
 978         WARN_ON(ret);
 979         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
 980         WARN_ON(ret);
 981         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
 982         WARN_ON(ret);
 983         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
 984         WARN_ON(ret);
 985         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
 986         WARN_ON(ret);
 987         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
 988         WARN_ON(ret);
 989         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
 990         WARN_ON(ret);
 991         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
 992         WARN_ON(ret);
 993         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
 994         WARN_ON(ret);
 995         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
 996         WARN_ON(ret);
 997         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
 998         WARN_ON(ret);
 999         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1000         WARN_ON(ret);
1001         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1002         WARN_ON(ret);
1003         ret = register_trace_block_split(blk_add_trace_split, NULL);
1004         WARN_ON(ret);
1005         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1006         WARN_ON(ret);
1007         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1008         WARN_ON(ret);
1009 }
1010
1011 static void blk_unregister_tracepoints(void)
1012 {
1013         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1014         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1015         unregister_trace_block_split(blk_add_trace_split, NULL);
1016         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1017         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1018         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1019         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1020         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1021         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1022         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1023         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1024         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1025         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1026         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1027         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1028         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1029         unregister_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
1030
1031         tracepoint_synchronize_unregister();
1032 }
1033
1034 /*
1035  * struct blk_io_tracer formatting routines
1036  */
1037
1038 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1039 {
1040         int i = 0;
1041         int tc = t->action >> BLK_TC_SHIFT;
1042
1043         if (t->action == BLK_TN_MESSAGE) {
1044                 rwbs[i++] = 'N';
1045                 goto out;
1046         }
1047
1048         if (tc & BLK_TC_FLUSH)
1049                 rwbs[i++] = 'F';
1050
1051         if (tc & BLK_TC_DISCARD)
1052                 rwbs[i++] = 'D';
1053         else if (tc & BLK_TC_WRITE)
1054                 rwbs[i++] = 'W';
1055         else if (t->bytes)
1056                 rwbs[i++] = 'R';
1057         else
1058                 rwbs[i++] = 'N';
1059
1060         if (tc & BLK_TC_FUA)
1061                 rwbs[i++] = 'F';
1062         if (tc & BLK_TC_AHEAD)
1063                 rwbs[i++] = 'A';
1064         if (tc & BLK_TC_SYNC)
1065                 rwbs[i++] = 'S';
1066         if (tc & BLK_TC_META)
1067                 rwbs[i++] = 'M';
1068 out:
1069         rwbs[i] = '\0';
1070 }
1071
1072 static inline
1073 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1074 {
1075         return (const struct blk_io_trace *)ent;
1076 }
1077
1078 static inline const void *pdu_start(const struct trace_entry *ent)
1079 {
1080         return te_blk_io_trace(ent) + 1;
1081 }
1082
1083 static inline u32 t_action(const struct trace_entry *ent)
1084 {
1085         return te_blk_io_trace(ent)->action;
1086 }
1087
1088 static inline u32 t_bytes(const struct trace_entry *ent)
1089 {
1090         return te_blk_io_trace(ent)->bytes;
1091 }
1092
1093 static inline u32 t_sec(const struct trace_entry *ent)
1094 {
1095         return te_blk_io_trace(ent)->bytes >> 9;
1096 }
1097
1098 static inline unsigned long long t_sector(const struct trace_entry *ent)
1099 {
1100         return te_blk_io_trace(ent)->sector;
1101 }
1102
1103 static inline __u16 t_error(const struct trace_entry *ent)
1104 {
1105         return te_blk_io_trace(ent)->error;
1106 }
1107
1108 static __u64 get_pdu_int(const struct trace_entry *ent)
1109 {
1110         const __u64 *val = pdu_start(ent);
1111         return be64_to_cpu(*val);
1112 }
1113
1114 static void get_pdu_remap(const struct trace_entry *ent,
1115                           struct blk_io_trace_remap *r)
1116 {
1117         const struct blk_io_trace_remap *__r = pdu_start(ent);
1118         __u64 sector_from = __r->sector_from;
1119
1120         r->device_from = be32_to_cpu(__r->device_from);
1121         r->device_to   = be32_to_cpu(__r->device_to);
1122         r->sector_from = be64_to_cpu(sector_from);
1123 }
1124
1125 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1126
1127 static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1128 {
1129         char rwbs[RWBS_LEN];
1130         unsigned long long ts  = iter->ts;
1131         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1132         unsigned secs          = (unsigned long)ts;
1133         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1134
1135         fill_rwbs(rwbs, t);
1136
1137         return trace_seq_printf(&iter->seq,
1138                                 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1139                                 MAJOR(t->device), MINOR(t->device), iter->cpu,
1140                                 secs, nsec_rem, iter->ent->pid, act, rwbs);
1141 }
1142
1143 static int blk_log_action(struct trace_iterator *iter, const char *act)
1144 {
1145         char rwbs[RWBS_LEN];
1146         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1147
1148         fill_rwbs(rwbs, t);
1149         return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1150                                 MAJOR(t->device), MINOR(t->device), act, rwbs);
1151 }
1152
1153 static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1154 {
1155         const unsigned char *pdu_buf;
1156         int pdu_len;
1157         int i, end, ret;
1158
1159         pdu_buf = pdu_start(ent);
1160         pdu_len = te_blk_io_trace(ent)->pdu_len;
1161
1162         if (!pdu_len)
1163                 return 1;
1164
1165         /* find the last zero that needs to be printed */
1166         for (end = pdu_len - 1; end >= 0; end--)
1167                 if (pdu_buf[end])
1168                         break;
1169         end++;
1170
1171         if (!trace_seq_putc(s, '('))
1172                 return 0;
1173
1174         for (i = 0; i < pdu_len; i++) {
1175
1176                 ret = trace_seq_printf(s, "%s%02x",
1177                                        i == 0 ? "" : " ", pdu_buf[i]);
1178                 if (!ret)
1179                         return ret;
1180
1181                 /*
1182                  * stop when the rest is just zeroes and indicate so
1183                  * with a ".." appended
1184                  */
1185                 if (i == end && end != pdu_len - 1)
1186                         return trace_seq_puts(s, " ..) ");
1187         }
1188
1189         return trace_seq_puts(s, ") ");
1190 }
1191
1192 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1193 {
1194         char cmd[TASK_COMM_LEN];
1195
1196         trace_find_cmdline(ent->pid, cmd);
1197
1198         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1199                 int ret;
1200
1201                 ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1202                 if (!ret)
1203                         return 0;
1204                 ret = blk_log_dump_pdu(s, ent);
1205                 if (!ret)
1206                         return 0;
1207                 return trace_seq_printf(s, "[%s]\n", cmd);
1208         } else {
1209                 if (t_sec(ent))
1210                         return trace_seq_printf(s, "%llu + %u [%s]\n",
1211                                                 t_sector(ent), t_sec(ent), cmd);
1212                 return trace_seq_printf(s, "[%s]\n", cmd);
1213         }
1214 }
1215
1216 static int blk_log_with_error(struct trace_seq *s,
1217                               const struct trace_entry *ent)
1218 {
1219         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1220                 int ret;
1221
1222                 ret = blk_log_dump_pdu(s, ent);
1223                 if (ret)
1224                         return trace_seq_printf(s, "[%d]\n", t_error(ent));
1225                 return 0;
1226         } else {
1227                 if (t_sec(ent))
1228                         return trace_seq_printf(s, "%llu + %u [%d]\n",
1229                                                 t_sector(ent),
1230                                                 t_sec(ent), t_error(ent));
1231                 return trace_seq_printf(s, "%llu [%d]\n",
1232                                         t_sector(ent), t_error(ent));
1233         }
1234 }
1235
1236 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1237 {
1238         struct blk_io_trace_remap r = { .device_from = 0, };
1239
1240         get_pdu_remap(ent, &r);
1241         return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1242                                 t_sector(ent), t_sec(ent),
1243                                 MAJOR(r.device_from), MINOR(r.device_from),
1244                                 (unsigned long long)r.sector_from);
1245 }
1246
1247 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1248 {
1249         char cmd[TASK_COMM_LEN];
1250
1251         trace_find_cmdline(ent->pid, cmd);
1252
1253         return trace_seq_printf(s, "[%s]\n", cmd);
1254 }
1255
1256 static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1257 {
1258         char cmd[TASK_COMM_LEN];
1259
1260         trace_find_cmdline(ent->pid, cmd);
1261
1262         return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1263 }
1264
1265 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1266 {
1267         char cmd[TASK_COMM_LEN];
1268
1269         trace_find_cmdline(ent->pid, cmd);
1270
1271         return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1272                                 get_pdu_int(ent), cmd);
1273 }
1274
1275 static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1276 {
1277         int ret;
1278         const struct blk_io_trace *t = te_blk_io_trace(ent);
1279
1280         ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1281         if (ret)
1282                 return trace_seq_putc(s, '\n');
1283         return ret;
1284 }
1285
1286 /*
1287  * struct tracer operations
1288  */
1289
1290 static void blk_tracer_print_header(struct seq_file *m)
1291 {
1292         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1293                 return;
1294         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1295                     "#  |     |     |           |   |   |\n");
1296 }
1297
1298 static void blk_tracer_start(struct trace_array *tr)
1299 {
1300         blk_tracer_enabled = true;
1301 }
1302
1303 static int blk_tracer_init(struct trace_array *tr)
1304 {
1305         blk_tr = tr;
1306         blk_tracer_start(tr);
1307         return 0;
1308 }
1309
1310 static void blk_tracer_stop(struct trace_array *tr)
1311 {
1312         blk_tracer_enabled = false;
1313 }
1314
1315 static void blk_tracer_reset(struct trace_array *tr)
1316 {
1317         blk_tracer_stop(tr);
1318 }
1319
1320 static const struct {
1321         const char *act[2];
1322         int        (*print)(struct trace_seq *s, const struct trace_entry *ent);
1323 } what2act[] = {
1324         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1325         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1326         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1327         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1328         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1329         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1330         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1331         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1332         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1333         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1334         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1335         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1336         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1337         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1338         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1339 };
1340
1341 static enum print_line_t print_one_line(struct trace_iterator *iter,
1342                                         bool classic)
1343 {
1344         struct trace_seq *s = &iter->seq;
1345         const struct blk_io_trace *t;
1346         u16 what;
1347         int ret;
1348         bool long_act;
1349         blk_log_action_t *log_action;
1350
1351         t          = te_blk_io_trace(iter->ent);
1352         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1353         long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1354         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1355
1356         if (t->action == BLK_TN_MESSAGE) {
1357                 ret = log_action(iter, long_act ? "message" : "m");
1358                 if (ret)
1359                         ret = blk_log_msg(s, iter->ent);
1360                 goto out;
1361         }
1362
1363         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1364                 ret = trace_seq_printf(s, "Unknown action %x\n", what);
1365         else {
1366                 ret = log_action(iter, what2act[what].act[long_act]);
1367                 if (ret)
1368                         ret = what2act[what].print(s, iter->ent);
1369         }
1370 out:
1371         return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1372 }
1373
1374 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1375                                                int flags, struct trace_event *event)
1376 {
1377         return print_one_line(iter, false);
1378 }
1379
1380 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1381 {
1382         struct trace_seq *s = &iter->seq;
1383         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1384         const int offset = offsetof(struct blk_io_trace, sector);
1385         struct blk_io_trace old = {
1386                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1387                 .time     = iter->ts,
1388         };
1389
1390         if (!trace_seq_putmem(s, &old, offset))
1391                 return 0;
1392         return trace_seq_putmem(s, &t->sector,
1393                                 sizeof(old) - offset + t->pdu_len);
1394 }
1395
1396 static enum print_line_t
1397 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1398                              struct trace_event *event)
1399 {
1400         return blk_trace_synthesize_old_trace(iter) ?
1401                         TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1402 }
1403
1404 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1405 {
1406         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1407                 return TRACE_TYPE_UNHANDLED;
1408
1409         return print_one_line(iter, true);
1410 }
1411
1412 static int blk_tracer_set_flag(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                         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1418                 else
1419                         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_ftrace_event(&trace_blk_event)) {
1449                 pr_warning("Warning: could not register block events\n");
1450                 return 1;
1451         }
1452
1453         if (register_tracer(&blk_tracer) != 0) {
1454                 pr_warning("Warning: could not register the block tracer\n");
1455                 unregister_ftrace_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 *old_bt, *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         old_bt = xchg(&q->blk_trace, bt);
1502         if (old_bt != NULL) {
1503                 (void)xchg(&q->blk_trace, old_bt);
1504                 ret = -EBUSY;
1505                 goto free_bt;
1506         }
1507
1508         if (atomic_inc_return(&blk_probes_ref) == 1)
1509                 blk_register_tracepoints();
1510         return 0;
1511
1512 free_bt:
1513         blk_trace_free(bt);
1514         return ret;
1515 }
1516
1517 /*
1518  * sysfs interface to enable and configure tracing
1519  */
1520
1521 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1522                                          struct device_attribute *attr,
1523                                          char *buf);
1524 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1525                                           struct device_attribute *attr,
1526                                           const char *buf, size_t count);
1527 #define BLK_TRACE_DEVICE_ATTR(_name) \
1528         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1529                     sysfs_blk_trace_attr_show, \
1530                     sysfs_blk_trace_attr_store)
1531
1532 static BLK_TRACE_DEVICE_ATTR(enable);
1533 static BLK_TRACE_DEVICE_ATTR(act_mask);
1534 static BLK_TRACE_DEVICE_ATTR(pid);
1535 static BLK_TRACE_DEVICE_ATTR(start_lba);
1536 static BLK_TRACE_DEVICE_ATTR(end_lba);
1537
1538 static struct attribute *blk_trace_attrs[] = {
1539         &dev_attr_enable.attr,
1540         &dev_attr_act_mask.attr,
1541         &dev_attr_pid.attr,
1542         &dev_attr_start_lba.attr,
1543         &dev_attr_end_lba.attr,
1544         NULL
1545 };
1546
1547 struct attribute_group blk_trace_attr_group = {
1548         .name  = "trace",
1549         .attrs = blk_trace_attrs,
1550 };
1551
1552 static const struct {
1553         int mask;
1554         const char *str;
1555 } mask_maps[] = {
1556         { BLK_TC_READ,          "read"          },
1557         { BLK_TC_WRITE,         "write"         },
1558         { BLK_TC_FLUSH,         "flush"         },
1559         { BLK_TC_SYNC,          "sync"          },
1560         { BLK_TC_QUEUE,         "queue"         },
1561         { BLK_TC_REQUEUE,       "requeue"       },
1562         { BLK_TC_ISSUE,         "issue"         },
1563         { BLK_TC_COMPLETE,      "complete"      },
1564         { BLK_TC_FS,            "fs"            },
1565         { BLK_TC_PC,            "pc"            },
1566         { BLK_TC_AHEAD,         "ahead"         },
1567         { BLK_TC_META,          "meta"          },
1568         { BLK_TC_DISCARD,       "discard"       },
1569         { BLK_TC_DRV_DATA,      "drv_data"      },
1570         { BLK_TC_FUA,           "fua"           },
1571 };
1572
1573 static int blk_trace_str2mask(const char *str)
1574 {
1575         int i;
1576         int mask = 0;
1577         char *buf, *s, *token;
1578
1579         buf = kstrdup(str, GFP_KERNEL);
1580         if (buf == NULL)
1581                 return -ENOMEM;
1582         s = strstrip(buf);
1583
1584         while (1) {
1585                 token = strsep(&s, ",");
1586                 if (token == NULL)
1587                         break;
1588
1589                 if (*token == '\0')
1590                         continue;
1591
1592                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1593                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1594                                 mask |= mask_maps[i].mask;
1595                                 break;
1596                         }
1597                 }
1598                 if (i == ARRAY_SIZE(mask_maps)) {
1599                         mask = -EINVAL;
1600                         break;
1601                 }
1602         }
1603         kfree(buf);
1604
1605         return mask;
1606 }
1607
1608 static ssize_t blk_trace_mask2str(char *buf, int mask)
1609 {
1610         int i;
1611         char *p = buf;
1612
1613         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1614                 if (mask & mask_maps[i].mask) {
1615                         p += sprintf(p, "%s%s",
1616                                     (p == buf) ? "" : ",", mask_maps[i].str);
1617                 }
1618         }
1619         *p++ = '\n';
1620
1621         return p - buf;
1622 }
1623
1624 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1625 {
1626         if (bdev->bd_disk == NULL)
1627                 return NULL;
1628
1629         return bdev_get_queue(bdev);
1630 }
1631
1632 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1633                                          struct device_attribute *attr,
1634                                          char *buf)
1635 {
1636         struct hd_struct *p = dev_to_part(dev);
1637         struct request_queue *q;
1638         struct block_device *bdev;
1639         ssize_t ret = -ENXIO;
1640
1641         bdev = bdget(part_devt(p));
1642         if (bdev == NULL)
1643                 goto out;
1644
1645         q = blk_trace_get_queue(bdev);
1646         if (q == NULL)
1647                 goto out_bdput;
1648
1649         mutex_lock(&bdev->bd_mutex);
1650
1651         if (attr == &dev_attr_enable) {
1652                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1653                 goto out_unlock_bdev;
1654         }
1655
1656         if (q->blk_trace == NULL)
1657                 ret = sprintf(buf, "disabled\n");
1658         else if (attr == &dev_attr_act_mask)
1659                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1660         else if (attr == &dev_attr_pid)
1661                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1662         else if (attr == &dev_attr_start_lba)
1663                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1664         else if (attr == &dev_attr_end_lba)
1665                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1666
1667 out_unlock_bdev:
1668         mutex_unlock(&bdev->bd_mutex);
1669 out_bdput:
1670         bdput(bdev);
1671 out:
1672         return ret;
1673 }
1674
1675 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1676                                           struct device_attribute *attr,
1677                                           const char *buf, size_t count)
1678 {
1679         struct block_device *bdev;
1680         struct request_queue *q;
1681         struct hd_struct *p;
1682         u64 value;
1683         ssize_t ret = -EINVAL;
1684
1685         if (count == 0)
1686                 goto out;
1687
1688         if (attr == &dev_attr_act_mask) {
1689                 if (sscanf(buf, "%llx", &value) != 1) {
1690                         /* Assume it is a list of trace category names */
1691                         ret = blk_trace_str2mask(buf);
1692                         if (ret < 0)
1693                                 goto out;
1694                         value = ret;
1695                 }
1696         } else if (sscanf(buf, "%llu", &value) != 1)
1697                 goto out;
1698
1699         ret = -ENXIO;
1700
1701         p = dev_to_part(dev);
1702         bdev = bdget(part_devt(p));
1703         if (bdev == NULL)
1704                 goto out;
1705
1706         q = blk_trace_get_queue(bdev);
1707         if (q == NULL)
1708                 goto out_bdput;
1709
1710         mutex_lock(&bdev->bd_mutex);
1711
1712         if (attr == &dev_attr_enable) {
1713                 if (value)
1714                         ret = blk_trace_setup_queue(q, bdev);
1715                 else
1716                         ret = blk_trace_remove_queue(q);
1717                 goto out_unlock_bdev;
1718         }
1719
1720         ret = 0;
1721         if (q->blk_trace == NULL)
1722                 ret = blk_trace_setup_queue(q, bdev);
1723
1724         if (ret == 0) {
1725                 if (attr == &dev_attr_act_mask)
1726                         q->blk_trace->act_mask = value;
1727                 else if (attr == &dev_attr_pid)
1728                         q->blk_trace->pid = value;
1729                 else if (attr == &dev_attr_start_lba)
1730                         q->blk_trace->start_lba = value;
1731                 else if (attr == &dev_attr_end_lba)
1732                         q->blk_trace->end_lba = value;
1733         }
1734
1735 out_unlock_bdev:
1736         mutex_unlock(&bdev->bd_mutex);
1737 out_bdput:
1738         bdput(bdev);
1739 out:
1740         return ret ? ret : count;
1741 }
1742
1743 int blk_trace_init_sysfs(struct device *dev)
1744 {
1745         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1746 }
1747
1748 void blk_trace_remove_sysfs(struct device *dev)
1749 {
1750         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1751 }
1752
1753 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1754
1755 #ifdef CONFIG_EVENT_TRACING
1756
1757 void blk_dump_cmd(char *buf, struct request *rq)
1758 {
1759         int i, end;
1760         int len = rq->cmd_len;
1761         unsigned char *cmd = rq->cmd;
1762
1763         if (rq->cmd_type != REQ_TYPE_BLOCK_PC) {
1764                 buf[0] = '\0';
1765                 return;
1766         }
1767
1768         for (end = len - 1; end >= 0; end--)
1769                 if (cmd[end])
1770                         break;
1771         end++;
1772
1773         for (i = 0; i < len; i++) {
1774                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1775                 if (i == end && end != len - 1) {
1776                         sprintf(buf, " ..");
1777                         break;
1778                 }
1779         }
1780 }
1781
1782 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1783 {
1784         int i = 0;
1785
1786         if (rw & REQ_FLUSH)
1787                 rwbs[i++] = 'F';
1788
1789         if (rw & WRITE)
1790                 rwbs[i++] = 'W';
1791         else if (rw & REQ_DISCARD)
1792                 rwbs[i++] = 'D';
1793         else if (bytes)
1794                 rwbs[i++] = 'R';
1795         else
1796                 rwbs[i++] = 'N';
1797
1798         if (rw & REQ_FUA)
1799                 rwbs[i++] = 'F';
1800         if (rw & REQ_RAHEAD)
1801                 rwbs[i++] = 'A';
1802         if (rw & REQ_SYNC)
1803                 rwbs[i++] = 'S';
1804         if (rw & REQ_META)
1805                 rwbs[i++] = 'M';
1806         if (rw & REQ_SECURE)
1807                 rwbs[i++] = 'E';
1808
1809         rwbs[i] = '\0';
1810 }
1811
1812 #endif /* CONFIG_EVENT_TRACING */
1813