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   1 /*
   2  * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  16  *
  17  */
  18 #include <linux/kernel.h>
  19 #include <linux/blkdev.h>
  20 #include <linux/blktrace_api.h>
  21 #include <linux/percpu.h>
  22 #include <linux/init.h>
  23 #include <linux/mutex.h>
  24 #include <linux/debugfs.h>
  25 #include <linux/smp_lock.h>
  26 #include <linux/time.h>
  27 #include <linux/uaccess.h>
  28
  29 #include <trace/events/block.h>
  30
  31 #include "trace_output.h"
  32
  33 #ifdef CONFIG_BLK_DEV_IO_TRACE
  34
  35 static unsigned int blktrace_seq __read_mostly = 1;
  36
  37 static struct trace_array *blk_tr;
  38 static bool blk_tracer_enabled __read_mostly;
  39
  40 /* Select an alternative, minimalistic output than the original one */
  41 #define TRACE_BLK_OPT_CLASSIC   0x1
  42
  43 static struct tracer_opt blk_tracer_opts[] = {
  44         /* Default disable the minimalistic output */
  45         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
  46         { }
  47 };
  48
  49 static struct tracer_flags blk_tracer_flags = {
  50         .val  = 0,
  51         .opts = blk_tracer_opts,
  52 };
  53
  54 /* Global reference count of probes */
  55 static atomic_t blk_probes_ref = ATOMIC_INIT(0);
  56
  57 static void blk_register_tracepoints(void);
  58 static void blk_unregister_tracepoints(void);
  59
  60 /*
  61  * Send out a notify message.
  62  */
  63 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
  64                        const void *data, size_t len)
  65 {
  66         struct blk_io_trace *t;
  67         struct ring_buffer_event *event = NULL;
  68         struct ring_buffer *buffer = NULL;
  69         int pc = 0;
  70         int cpu = smp_processor_id();
  71         bool blk_tracer = blk_tracer_enabled;
  72
  73         if (blk_tracer) {
  74                 buffer = blk_tr->buffer;
  75                 pc = preempt_count();
  76                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
  77                                                   sizeof(*t) + len,
  78                                                   0, pc);
  79                 if (!event)
  80                         return;
  81                 t = ring_buffer_event_data(event);
  82                 goto record_it;
  83         }
  84
  85         if (!bt->rchan)
  86                 return;
  87
  88         t = relay_reserve(bt->rchan, sizeof(*t) + len);
  89         if (t) {
  90                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
  91                 t->time = ktime_to_ns(ktime_get());
  92 record_it:
  93                 t->device = bt->dev;
  94                 t->action = action;
  95                 t->pid = pid;
  96                 t->cpu = cpu;
  97                 t->pdu_len = len;
  98                 memcpy((void *) t + sizeof(*t), data, len);
  99
 100                 if (blk_tracer)
 101                         trace_buffer_unlock_commit(buffer, event, 0, pc);
 102         }
 103 }
 104
 105 /*
 106  * Send out a notify for this process, if we haven't done so since a trace
 107  * started
 108  */
 109 static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
 110 {
 111         tsk->btrace_seq = blktrace_seq;
 112         trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));
 113 }
 114
 115 static void trace_note_time(struct blk_trace *bt)
 116 {
 117         struct timespec now;
 118         unsigned long flags;
 119         u32 words[2];
 120
 121         getnstimeofday(&now);
 122         words[0] = now.tv_sec;
 123         words[1] = now.tv_nsec;
 124
 125         local_irq_save(flags);
 126         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
 127         local_irq_restore(flags);
 128 }
 129
 130 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 131 {
 132         int n;
 133         va_list args;
 134         unsigned long flags;
 135         char *buf;
 136
 137         if (unlikely(bt->trace_state != Blktrace_running &&
 138                      !blk_tracer_enabled))
 139                 return;
 140
 141         local_irq_save(flags);
 142         buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
 143         va_start(args, fmt);
 144         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 145         va_end(args);
 146
 147         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
 148         local_irq_restore(flags);
 149 }
 150 EXPORT_SYMBOL_GPL(__trace_note_message);
 151
 152 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
 153                          pid_t pid)
 154 {
 155         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
 156                 return 1;
 157         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
 158                 return 1;
 159         if (bt->pid && pid != bt->pid)
 160                 return 1;
 161
 162         return 0;
 163 }
 164
 165 /*
 166  * Data direction bit lookup
 167  */
 168 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
 169                                  BLK_TC_ACT(BLK_TC_WRITE) };
 170
 171 /* The ilog2() calls fall out because they're constant */
 172 #define MASK_TC_BIT(rw, __name) ((rw & (1 << BIO_RW_ ## __name)) << \
 173           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - BIO_RW_ ## __name))
 174
 175 /*
 176  * The worker for the various blk_add_trace*() types. Fills out a
 177  * blk_io_trace structure and places it in a per-cpu subbuffer.
 178  */
 179 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 180                      int rw, u32 what, int error, int pdu_len, void *pdu_data)
 181 {
 182         struct task_struct *tsk = current;
 183         struct ring_buffer_event *event = NULL;
 184         struct ring_buffer *buffer = NULL;
 185         struct blk_io_trace *t;
 186         unsigned long flags = 0;
 187         unsigned long *sequence;
 188         pid_t pid;
 189         int cpu, pc = 0;
 190         bool blk_tracer = blk_tracer_enabled;
 191
 192         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
 193                 return;
 194
 195         what |= ddir_act[rw & WRITE];
 196         what |= MASK_TC_BIT(rw, BARRIER);
 197         what |= MASK_TC_BIT(rw, SYNCIO);
 198         what |= MASK_TC_BIT(rw, AHEAD);
 199         what |= MASK_TC_BIT(rw, META);
 200         what |= MASK_TC_BIT(rw, DISCARD);
 201
 202         pid = tsk->pid;
 203         if (act_log_check(bt, what, sector, pid))
 204                 return;
 205         cpu = raw_smp_processor_id();
 206
 207         if (blk_tracer) {
 208                 tracing_record_cmdline(current);
 209
 210                 buffer = blk_tr->buffer;
 211                 pc = preempt_count();
 212                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 213                                                   sizeof(*t) + pdu_len,
 214                                                   0, pc);
 215                 if (!event)
 216                         return;
 217                 t = ring_buffer_event_data(event);
 218                 goto record_it;
 219         }
 220
 221         /*
 222          * A word about the locking here - we disable interrupts to reserve
 223          * some space in the relay per-cpu buffer, to prevent an irq
 224          * from coming in and stepping on our toes.
 225          */
 226         local_irq_save(flags);
 227
 228         if (unlikely(tsk->btrace_seq != blktrace_seq))
 229                 trace_note_tsk(bt, tsk);
 230
 231         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
 232         if (t) {
 233                 sequence = per_cpu_ptr(bt->sequence, cpu);
 234
 235                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 236                 t->sequence = ++(*sequence);
 237                 t->time = ktime_to_ns(ktime_get());
 238 record_it:
 239                 /*
 240                  * These two are not needed in ftrace as they are in the
 241                  * generic trace_entry, filled by tracing_generic_entry_update,
 242                  * but for the trace_event->bin() synthesizer benefit we do it
 243                  * here too.
 244                  */
 245                 t->cpu = cpu;
 246                 t->pid = pid;
 247
 248                 t->sector = sector;
 249                 t->bytes = bytes;
 250                 t->action = what;
 251                 t->device = bt->dev;
 252                 t->error = error;
 253                 t->pdu_len = pdu_len;
 254
 255                 if (pdu_len)
 256                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
 257
 258                 if (blk_tracer) {
 259                         trace_buffer_unlock_commit(buffer, event, 0, pc);
 260                         return;
 261                 }
 262         }
 263
 264         local_irq_restore(flags);
 265 }
 266
 267 static struct dentry *blk_tree_root;
 268 static DEFINE_MUTEX(blk_tree_mutex);
 269
 270 static void blk_trace_free(struct blk_trace *bt)
 271 {
 272         debugfs_remove(bt->msg_file);
 273         debugfs_remove(bt->dropped_file);
 274         relay_close(bt->rchan);
 275         debugfs_remove(bt->dir);
 276         free_percpu(bt->sequence);
 277         free_percpu(bt->msg_data);
 278         kfree(bt);
 279 }
 280
 281 static void blk_trace_cleanup(struct blk_trace *bt)
 282 {
 283         blk_trace_free(bt);
 284         if (atomic_dec_and_test(&blk_probes_ref))
 285                 blk_unregister_tracepoints();
 286 }
 287
 288 int blk_trace_remove(struct request_queue *q)
 289 {
 290         struct blk_trace *bt;
 291
 292         bt = xchg(&q->blk_trace, NULL);
 293         if (!bt)
 294                 return -EINVAL;
 295
 296         if (bt->trace_state != Blktrace_running)
 297                 blk_trace_cleanup(bt);
 298
 299         return 0;
 300 }
 301 EXPORT_SYMBOL_GPL(blk_trace_remove);
 302
 303 static int blk_dropped_open(struct inode *inode, struct file *filp)
 304 {
 305         filp->private_data = inode->i_private;
 306
 307         return 0;
 308 }
 309
 310 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
 311                                 size_t count, loff_t *ppos)
 312 {
 313         struct blk_trace *bt = filp->private_data;
 314         char buf[16];
 315
 316         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
 317
 318         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 319 }
 320
 321 static const struct file_operations blk_dropped_fops = {
 322         .owner =        THIS_MODULE,
 323         .open =         blk_dropped_open,
 324         .read =         blk_dropped_read,
 325 };
 326
 327 static int blk_msg_open(struct inode *inode, struct file *filp)
 328 {
 329         filp->private_data = inode->i_private;
 330
 331         return 0;
 332 }
 333
 334 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 335                                 size_t count, loff_t *ppos)
 336 {
 337         char *msg;
 338         struct blk_trace *bt;
 339
 340         if (count >= BLK_TN_MAX_MSG)
 341                 return -EINVAL;
 342
 343         msg = kmalloc(count + 1, GFP_KERNEL);
 344         if (msg == NULL)
 345                 return -ENOMEM;
 346
 347         if (copy_from_user(msg, buffer, count)) {
 348                 kfree(msg);
 349                 return -EFAULT;
 350         }
 351
 352         msg[count] = '\0';
 353         bt = filp->private_data;
 354         __trace_note_message(bt, "%s", msg);
 355         kfree(msg);
 356
 357         return count;
 358 }
 359
 360 static const struct file_operations blk_msg_fops = {
 361         .owner =        THIS_MODULE,
 362         .open =         blk_msg_open,
 363         .write =        blk_msg_write,
 364 };
 365
 366 /*
 367  * Keep track of how many times we encountered a full subbuffer, to aid
 368  * the user space app in telling how many lost events there were.
 369  */
 370 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
 371                                      void *prev_subbuf, size_t prev_padding)
 372 {
 373         struct blk_trace *bt;
 374
 375         if (!relay_buf_full(buf))
 376                 return 1;
 377
 378         bt = buf->chan->private_data;
 379         atomic_inc(&bt->dropped);
 380         return 0;
 381 }
 382
 383 static int blk_remove_buf_file_callback(struct dentry *dentry)
 384 {
 385         debugfs_remove(dentry);
 386
 387         return 0;
 388 }
 389
 390 static struct dentry *blk_create_buf_file_callback(const char *filename,
 391                                                    struct dentry *parent,
 392                                                    int mode,
 393                                                    struct rchan_buf *buf,
 394                                                    int *is_global)
 395 {
 396         return debugfs_create_file(filename, mode, parent, buf,
 397                                         &relay_file_operations);
 398 }
 399
 400 static struct rchan_callbacks blk_relay_callbacks = {
 401         .subbuf_start           = blk_subbuf_start_callback,
 402         .create_buf_file        = blk_create_buf_file_callback,
 403         .remove_buf_file        = blk_remove_buf_file_callback,
 404 };
 405
 406 static void blk_trace_setup_lba(struct blk_trace *bt,
 407                                 struct block_device *bdev)
 408 {
 409         struct hd_struct *part = NULL;
 410
 411         if (bdev)
 412                 part = bdev->bd_part;
 413
 414         if (part) {
 415                 bt->start_lba = part->start_sect;
 416                 bt->end_lba = part->start_sect + part->nr_sects;
 417         } else {
 418                 bt->start_lba = 0;
 419                 bt->end_lba = -1ULL;
 420         }
 421 }
 422
 423 /*
 424  * Setup everything required to start tracing
 425  */
 426 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 427                        struct block_device *bdev,
 428                        struct blk_user_trace_setup *buts)
 429 {
 430         struct blk_trace *old_bt, *bt = NULL;
 431         struct dentry *dir = NULL;
 432         int ret, i;
 433
 434         if (!buts->buf_size || !buts->buf_nr)
 435                 return -EINVAL;
 436
 437         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 438         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 439
 440         /*
 441          * some device names have larger paths - convert the slashes
 442          * to underscores for this to work as expected
 443          */
 444         for (i = 0; i < strlen(buts->name); i++)
 445                 if (buts->name[i] == '/')
 446                         buts->name[i] = '_';
 447
 448         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 449         if (!bt)
 450                 return -ENOMEM;
 451
 452         ret = -ENOMEM;
 453         bt->sequence = alloc_percpu(unsigned long);
 454         if (!bt->sequence)
 455                 goto err;
 456
 457         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 458         if (!bt->msg_data)
 459                 goto err;
 460
 461         ret = -ENOENT;
 462
 463         mutex_lock(&blk_tree_mutex);
 464         if (!blk_tree_root) {
 465                 blk_tree_root = debugfs_create_dir("block", NULL);
 466                 if (!blk_tree_root) {
 467                         mutex_unlock(&blk_tree_mutex);
 468                         goto err;
 469                 }
 470         }
 471         mutex_unlock(&blk_tree_mutex);
 472
 473         dir = debugfs_create_dir(buts->name, blk_tree_root);
 474
 475         if (!dir)
 476                 goto err;
 477
 478         bt->dir = dir;
 479         bt->dev = dev;
 480         atomic_set(&bt->dropped, 0);
 481
 482         ret = -EIO;
 483         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 484                                                &blk_dropped_fops);
 485         if (!bt->dropped_file)
 486                 goto err;
 487
 488         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 489         if (!bt->msg_file)
 490                 goto err;
 491
 492         bt->rchan = relay_open("trace", dir, buts->buf_size,
 493                                 buts->buf_nr, &blk_relay_callbacks, bt);
 494         if (!bt->rchan)
 495                 goto err;
 496
 497         bt->act_mask = buts->act_mask;
 498         if (!bt->act_mask)
 499                 bt->act_mask = (u16) -1;
 500
 501         blk_trace_setup_lba(bt, bdev);
 502
 503         /* overwrite with user settings */
 504         if (buts->start_lba)
 505                 bt->start_lba = buts->start_lba;
 506         if (buts->end_lba)
 507                 bt->end_lba = buts->end_lba;
 508
 509         bt->pid = buts->pid;
 510         bt->trace_state = Blktrace_setup;
 511
 512         ret = -EBUSY;
 513         old_bt = xchg(&q->blk_trace, bt);
 514         if (old_bt) {
 515                 (void) xchg(&q->blk_trace, old_bt);
 516                 goto err;
 517         }
 518
 519         if (atomic_inc_return(&blk_probes_ref) == 1)
 520                 blk_register_tracepoints();
 521
 522         return 0;
 523 err:
 524         blk_trace_free(bt);
 525         return ret;
 526 }
 527
 528 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 529                     struct block_device *bdev,
 530                     char __user *arg)
 531 {
 532         struct blk_user_trace_setup buts;
 533         int ret;
 534
 535         ret = copy_from_user(&buts, arg, sizeof(buts));
 536         if (ret)
 537                 return -EFAULT;
 538
 539         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 540         if (ret)
 541                 return ret;
 542
 543         if (copy_to_user(arg, &buts, sizeof(buts))) {
 544                 blk_trace_remove(q);
 545                 return -EFAULT;
 546         }
 547         return 0;
 548 }
 549 EXPORT_SYMBOL_GPL(blk_trace_setup);
 550
 551 int blk_trace_startstop(struct request_queue *q, int start)
 552 {
 553         int ret;
 554         struct blk_trace *bt = q->blk_trace;
 555
 556         if (bt == NULL)
 557                 return -EINVAL;
 558
 559         /*
 560          * For starting a trace, we can transition from a setup or stopped
 561          * trace. For stopping a trace, the state must be running
 562          */
 563         ret = -EINVAL;
 564         if (start) {
 565                 if (bt->trace_state == Blktrace_setup ||
 566                     bt->trace_state == Blktrace_stopped) {
 567                         blktrace_seq++;
 568                         smp_mb();
 569                         bt->trace_state = Blktrace_running;
 570
 571                         trace_note_time(bt);
 572                         ret = 0;
 573                 }
 574         } else {
 575                 if (bt->trace_state == Blktrace_running) {
 576                         bt->trace_state = Blktrace_stopped;
 577                         relay_flush(bt->rchan);
 578                         ret = 0;
 579                 }
 580         }
 581
 582         return ret;
 583 }
 584 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 585
 586 /**
 587  * blk_trace_ioctl: - handle the ioctls associated with tracing
 588  * @bdev:       the block device
 589  * @cmd:        the ioctl cmd
 590  * @arg:        the argument data, if any
 591  *
 592  **/
 593 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 594 {
 595         struct request_queue *q;
 596         int ret, start = 0;
 597         char b[BDEVNAME_SIZE];
 598
 599         q = bdev_get_queue(bdev);
 600         if (!q)
 601                 return -ENXIO;
 602
 603         mutex_lock(&bdev->bd_mutex);
 604
 605         switch (cmd) {
 606         case BLKTRACESETUP:
 607                 bdevname(bdev, b);
 608                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 609                 break;
 610         case BLKTRACESTART:
 611                 start = 1;
 612         case BLKTRACESTOP:
 613                 ret = blk_trace_startstop(q, start);
 614                 break;
 615         case BLKTRACETEARDOWN:
 616                 ret = blk_trace_remove(q);
 617                 break;
 618         default:
 619                 ret = -ENOTTY;
 620                 break;
 621         }
 622
 623         mutex_unlock(&bdev->bd_mutex);
 624         return ret;
 625 }
 626
 627 /**
 628  * blk_trace_shutdown: - stop and cleanup trace structures
 629  * @q:    the request queue associated with the device
 630  *
 631  **/
 632 void blk_trace_shutdown(struct request_queue *q)
 633 {
 634         if (q->blk_trace) {
 635                 blk_trace_startstop(q, 0);
 636                 blk_trace_remove(q);
 637         }
 638 }
 639
 640 /*
 641  * blktrace probes
 642  */
 643
 644 /**
 645  * blk_add_trace_rq - Add a trace for a request oriented action
 646  * @q:          queue the io is for
 647  * @rq:         the source request
 648  * @what:       the action
 649  *
 650  * Description:
 651  *     Records an action against a request. Will log the bio offset + size.
 652  *
 653  **/
 654 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 655                                     u32 what)
 656 {
 657         struct blk_trace *bt = q->blk_trace;
 658         int rw = rq->cmd_flags & 0x03;
 659
 660         if (likely(!bt))
 661                 return;
 662
 663         if (blk_discard_rq(rq))
 664                 rw |= (1 << BIO_RW_DISCARD);
 665
 666         if (blk_pc_request(rq)) {
 667                 what |= BLK_TC_ACT(BLK_TC_PC);
 668                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), rw,
 669                                 what, rq->errors, rq->cmd_len, rq->cmd);
 670         } else  {
 671                 what |= BLK_TC_ACT(BLK_TC_FS);
 672                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), rw,
 673                                 what, rq->errors, 0, NULL);
 674         }
 675 }
 676
 677 static void blk_add_trace_rq_abort(struct request_queue *q, struct request *rq)
 678 {
 679         blk_add_trace_rq(q, rq, BLK_TA_ABORT);
 680 }
 681
 682 static void blk_add_trace_rq_insert(struct request_queue *q, struct request *rq)
 683 {
 684         blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 685 }
 686
 687 static void blk_add_trace_rq_issue(struct request_queue *q, struct request *rq)
 688 {
 689         blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
 690 }
 691
 692 static void blk_add_trace_rq_requeue(struct request_queue *q,
 693                                      struct request *rq)
 694 {
 695         blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
 696 }
 697
 698 static void blk_add_trace_rq_complete(struct request_queue *q,
 699                                       struct request *rq)
 700 {
 701         blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
 702 }
 703
 704 /**
 705  * blk_add_trace_bio - Add a trace for a bio oriented action
 706  * @q:          queue the io is for
 707  * @bio:        the source bio
 708  * @what:       the action
 709  *
 710  * Description:
 711  *     Records an action against a bio. Will log the bio offset + size.
 712  *
 713  **/
 714 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 715                                      u32 what)
 716 {
 717         struct blk_trace *bt = q->blk_trace;
 718
 719         if (likely(!bt))
 720                 return;
 721
 722         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
 723                         !bio_flagged(bio, BIO_UPTODATE), 0, NULL);
 724 }
 725
 726 static void blk_add_trace_bio_bounce(struct request_queue *q, struct bio *bio)
 727 {
 728         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE);
 729 }
 730
 731 static void blk_add_trace_bio_complete(struct request_queue *q, struct bio *bio)
 732 {
 733         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE);
 734 }
 735
 736 static void blk_add_trace_bio_backmerge(struct request_queue *q,
 737                                         struct bio *bio)
 738 {
 739         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
 740 }
 741
 742 static void blk_add_trace_bio_frontmerge(struct request_queue *q,
 743                                          struct bio *bio)
 744 {
 745         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
 746 }
 747
 748 static void blk_add_trace_bio_queue(struct request_queue *q, struct bio *bio)
 749 {
 750         blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
 751 }
 752
 753 static void blk_add_trace_getrq(struct request_queue *q,
 754                                 struct bio *bio, int rw)
 755 {
 756         if (bio)
 757                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ);
 758         else {
 759                 struct blk_trace *bt = q->blk_trace;
 760
 761                 if (bt)
 762                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
 763         }
 764 }
 765
 766
 767 static void blk_add_trace_sleeprq(struct request_queue *q,
 768                                   struct bio *bio, int rw)
 769 {
 770         if (bio)
 771                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ);
 772         else {
 773                 struct blk_trace *bt = q->blk_trace;
 774
 775                 if (bt)
 776                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
 777                                         0, 0, NULL);
 778         }
 779 }
 780
 781 static void blk_add_trace_plug(struct request_queue *q)
 782 {
 783         struct blk_trace *bt = q->blk_trace;
 784
 785         if (bt)
 786                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
 787 }
 788
 789 static void blk_add_trace_unplug_io(struct request_queue *q)
 790 {
 791         struct blk_trace *bt = q->blk_trace;
 792
 793         if (bt) {
 794                 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
 795                 __be64 rpdu = cpu_to_be64(pdu);
 796
 797                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_IO, 0,
 798                                 sizeof(rpdu), &rpdu);
 799         }
 800 }
 801
 802 static void blk_add_trace_unplug_timer(struct request_queue *q)
 803 {
 804         struct blk_trace *bt = q->blk_trace;
 805
 806         if (bt) {
 807                 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
 808                 __be64 rpdu = cpu_to_be64(pdu);
 809
 810                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_TIMER, 0,
 811                                 sizeof(rpdu), &rpdu);
 812         }
 813 }
 814
 815 static void blk_add_trace_split(struct request_queue *q, struct bio *bio,
 816                                 unsigned int pdu)
 817 {
 818         struct blk_trace *bt = q->blk_trace;
 819
 820         if (bt) {
 821                 __be64 rpdu = cpu_to_be64(pdu);
 822
 823                 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 824                                 BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
 825                                 sizeof(rpdu), &rpdu);
 826         }
 827 }
 828
 829 /**
 830  * blk_add_trace_remap - Add a trace for a remap operation
 831  * @q:          queue the io is for
 832  * @bio:        the source bio
 833  * @dev:        target device
 834  * @from:       source sector
 835  *
 836  * Description:
 837  *     Device mapper or raid target sometimes need to split a bio because
 838  *     it spans a stripe (or similar). Add a trace for that action.
 839  *
 840  **/
 841 static void blk_add_trace_remap(struct request_queue *q, struct bio *bio,
 842                                        dev_t dev, sector_t from)
 843 {
 844         struct blk_trace *bt = q->blk_trace;
 845         struct blk_io_trace_remap r;
 846
 847         if (likely(!bt))
 848                 return;
 849
 850         r.device_from = cpu_to_be32(dev);
 851         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
 852         r.sector_from = cpu_to_be64(from);
 853
 854         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 855                         BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE),
 856                         sizeof(r), &r);
 857 }
 858
 859 /**
 860  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
 861  * @q:          queue the io is for
 862  * @rq:         the source request
 863  * @dev:        target device
 864  * @from:       source sector
 865  *
 866  * Description:
 867  *     Device mapper remaps request to other devices.
 868  *     Add a trace for that action.
 869  *
 870  **/
 871 static void blk_add_trace_rq_remap(struct request_queue *q,
 872                                    struct request *rq, dev_t dev,
 873                                    sector_t from)
 874 {
 875         struct blk_trace *bt = q->blk_trace;
 876         struct blk_io_trace_remap r;
 877
 878         if (likely(!bt))
 879                 return;
 880
 881         r.device_from = cpu_to_be32(dev);
 882         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
 883         r.sector_from = cpu_to_be64(from);
 884
 885         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 886                         rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
 887                         sizeof(r), &r);
 888 }
 889
 890 /**
 891  * blk_add_driver_data - Add binary message with driver-specific data
 892  * @q:          queue the io is for
 893  * @rq:         io request
 894  * @data:       driver-specific data
 895  * @len:        length of driver-specific data
 896  *
 897  * Description:
 898  *     Some drivers might want to write driver-specific data per request.
 899  *
 900  **/
 901 void blk_add_driver_data(struct request_queue *q,
 902                          struct request *rq,
 903                          void *data, size_t len)
 904 {
 905         struct blk_trace *bt = q->blk_trace;
 906
 907         if (likely(!bt))
 908                 return;
 909
 910         if (blk_pc_request(rq))
 911                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
 912                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 913         else
 914                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
 915                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 916 }
 917 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 918
 919 static void blk_register_tracepoints(void)
 920 {
 921         int ret;
 922
 923         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort);
 924         WARN_ON(ret);
 925         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert);
 926         WARN_ON(ret);
 927         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue);
 928         WARN_ON(ret);
 929         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue);
 930         WARN_ON(ret);
 931         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete);
 932         WARN_ON(ret);
 933         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce);
 934         WARN_ON(ret);
 935         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete);
 936         WARN_ON(ret);
 937         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
 938         WARN_ON(ret);
 939         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
 940         WARN_ON(ret);
 941         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue);
 942         WARN_ON(ret);
 943         ret = register_trace_block_getrq(blk_add_trace_getrq);
 944         WARN_ON(ret);
 945         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq);
 946         WARN_ON(ret);
 947         ret = register_trace_block_plug(blk_add_trace_plug);
 948         WARN_ON(ret);
 949         ret = register_trace_block_unplug_timer(blk_add_trace_unplug_timer);
 950         WARN_ON(ret);
 951         ret = register_trace_block_unplug_io(blk_add_trace_unplug_io);
 952         WARN_ON(ret);
 953         ret = register_trace_block_split(blk_add_trace_split);
 954         WARN_ON(ret);
 955         ret = register_trace_block_remap(blk_add_trace_remap);
 956         WARN_ON(ret);
 957         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap);
 958         WARN_ON(ret);
 959 }
 960
 961 static void blk_unregister_tracepoints(void)
 962 {
 963         unregister_trace_block_rq_remap(blk_add_trace_rq_remap);
 964         unregister_trace_block_remap(blk_add_trace_remap);
 965         unregister_trace_block_split(blk_add_trace_split);
 966         unregister_trace_block_unplug_io(blk_add_trace_unplug_io);
 967         unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer);
 968         unregister_trace_block_plug(blk_add_trace_plug);
 969         unregister_trace_block_sleeprq(blk_add_trace_sleeprq);
 970         unregister_trace_block_getrq(blk_add_trace_getrq);
 971         unregister_trace_block_bio_queue(blk_add_trace_bio_queue);
 972         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
 973         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
 974         unregister_trace_block_bio_complete(blk_add_trace_bio_complete);
 975         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce);
 976         unregister_trace_block_rq_complete(blk_add_trace_rq_complete);
 977         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue);
 978         unregister_trace_block_rq_issue(blk_add_trace_rq_issue);
 979         unregister_trace_block_rq_insert(blk_add_trace_rq_insert);
 980         unregister_trace_block_rq_abort(blk_add_trace_rq_abort);
 981
 982         tracepoint_synchronize_unregister();
 983 }
 984
 985 /*
 986  * struct blk_io_tracer formatting routines
 987  */
 988
 989 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
 990 {
 991         int i = 0;
 992         int tc = t->action >> BLK_TC_SHIFT;
 993
 994         if (t->action == BLK_TN_MESSAGE) {
 995                 rwbs[i++] = 'N';
 996                 goto out;
 997         }
 998
 999         if (tc & BLK_TC_DISCARD)
1000                 rwbs[i++] = 'D';
1001         else if (tc & BLK_TC_WRITE)
1002                 rwbs[i++] = 'W';
1003         else if (t->bytes)
1004                 rwbs[i++] = 'R';
1005         else
1006                 rwbs[i++] = 'N';
1007
1008         if (tc & BLK_TC_AHEAD)
1009                 rwbs[i++] = 'A';
1010         if (tc & BLK_TC_BARRIER)
1011                 rwbs[i++] = 'B';
1012         if (tc & BLK_TC_SYNC)
1013                 rwbs[i++] = 'S';
1014         if (tc & BLK_TC_META)
1015                 rwbs[i++] = 'M';
1016 out:
1017         rwbs[i] = '\0';
1018 }
1019
1020 static inline
1021 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1022 {
1023         return (const struct blk_io_trace *)ent;
1024 }
1025
1026 static inline const void *pdu_start(const struct trace_entry *ent)
1027 {
1028         return te_blk_io_trace(ent) + 1;
1029 }
1030
1031 static inline u32 t_action(const struct trace_entry *ent)
1032 {
1033         return te_blk_io_trace(ent)->action;
1034 }
1035
1036 static inline u32 t_bytes(const struct trace_entry *ent)
1037 {
1038         return te_blk_io_trace(ent)->bytes;
1039 }
1040
1041 static inline u32 t_sec(const struct trace_entry *ent)
1042 {
1043         return te_blk_io_trace(ent)->bytes >> 9;
1044 }
1045
1046 static inline unsigned long long t_sector(const struct trace_entry *ent)
1047 {
1048         return te_blk_io_trace(ent)->sector;
1049 }
1050
1051 static inline __u16 t_error(const struct trace_entry *ent)
1052 {
1053         return te_blk_io_trace(ent)->error;
1054 }
1055
1056 static __u64 get_pdu_int(const struct trace_entry *ent)
1057 {
1058         const __u64 *val = pdu_start(ent);
1059         return be64_to_cpu(*val);
1060 }
1061
1062 static void get_pdu_remap(const struct trace_entry *ent,
1063                           struct blk_io_trace_remap *r)
1064 {
1065         const struct blk_io_trace_remap *__r = pdu_start(ent);
1066         __u64 sector_from = __r->sector_from;
1067
1068         r->device_from = be32_to_cpu(__r->device_from);
1069         r->device_to   = be32_to_cpu(__r->device_to);
1070         r->sector_from = be64_to_cpu(sector_from);
1071 }
1072
1073 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1074
1075 static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1076 {
1077         char rwbs[6];
1078         unsigned long long ts  = iter->ts;
1079         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1080         unsigned secs          = (unsigned long)ts;
1081         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1082
1083         fill_rwbs(rwbs, t);
1084
1085         return trace_seq_printf(&iter->seq,
1086                                 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1087                                 MAJOR(t->device), MINOR(t->device), iter->cpu,
1088                                 secs, nsec_rem, iter->ent->pid, act, rwbs);
1089 }
1090
1091 static int blk_log_action(struct trace_iterator *iter, const char *act)
1092 {
1093         char rwbs[6];
1094         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1095
1096         fill_rwbs(rwbs, t);
1097         return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1098                                 MAJOR(t->device), MINOR(t->device), act, rwbs);
1099 }
1100
1101 static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1102 {
1103         const unsigned char *pdu_buf;
1104         int pdu_len;
1105         int i, end, ret;
1106
1107         pdu_buf = pdu_start(ent);
1108         pdu_len = te_blk_io_trace(ent)->pdu_len;
1109
1110         if (!pdu_len)
1111                 return 1;
1112
1113         /* find the last zero that needs to be printed */
1114         for (end = pdu_len - 1; end >= 0; end--)
1115                 if (pdu_buf[end])
1116                         break;
1117         end++;
1118
1119         if (!trace_seq_putc(s, '('))
1120                 return 0;
1121
1122         for (i = 0; i < pdu_len; i++) {
1123
1124                 ret = trace_seq_printf(s, "%s%02x",
1125                                        i == 0 ? "" : " ", pdu_buf[i]);
1126                 if (!ret)
1127                         return ret;
1128
1129                 /*
1130                  * stop when the rest is just zeroes and indicate so
1131                  * with a ".." appended
1132                  */
1133                 if (i == end && end != pdu_len - 1)
1134                         return trace_seq_puts(s, " ..) ");
1135         }
1136
1137         return trace_seq_puts(s, ") ");
1138 }
1139
1140 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1141 {
1142         char cmd[TASK_COMM_LEN];
1143
1144         trace_find_cmdline(ent->pid, cmd);
1145
1146         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1147                 int ret;
1148
1149                 ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1150                 if (!ret)
1151                         return 0;
1152                 ret = blk_log_dump_pdu(s, ent);
1153                 if (!ret)
1154                         return 0;
1155                 return trace_seq_printf(s, "[%s]\n", cmd);
1156         } else {
1157                 if (t_sec(ent))
1158                         return trace_seq_printf(s, "%llu + %u [%s]\n",
1159                                                 t_sector(ent), t_sec(ent), cmd);
1160                 return trace_seq_printf(s, "[%s]\n", cmd);
1161         }
1162 }
1163
1164 static int blk_log_with_error(struct trace_seq *s,
1165                               const struct trace_entry *ent)
1166 {
1167         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1168                 int ret;
1169
1170                 ret = blk_log_dump_pdu(s, ent);
1171                 if (ret)
1172                         return trace_seq_printf(s, "[%d]\n", t_error(ent));
1173                 return 0;
1174         } else {
1175                 if (t_sec(ent))
1176                         return trace_seq_printf(s, "%llu + %u [%d]\n",
1177                                                 t_sector(ent),
1178                                                 t_sec(ent), t_error(ent));
1179                 return trace_seq_printf(s, "%llu [%d]\n",
1180                                         t_sector(ent), t_error(ent));
1181         }
1182 }
1183
1184 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1185 {
1186         struct blk_io_trace_remap r = { .device_from = 0, };
1187
1188         get_pdu_remap(ent, &r);
1189         return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1190                                 t_sector(ent), t_sec(ent),
1191                                 MAJOR(r.device_from), MINOR(r.device_from),
1192                                 (unsigned long long)r.sector_from);
1193 }
1194
1195 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1196 {
1197         char cmd[TASK_COMM_LEN];
1198
1199         trace_find_cmdline(ent->pid, cmd);
1200
1201         return trace_seq_printf(s, "[%s]\n", cmd);
1202 }
1203
1204 static int blk_log_unplug(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         return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1211 }
1212
1213 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1214 {
1215         char cmd[TASK_COMM_LEN];
1216
1217         trace_find_cmdline(ent->pid, cmd);
1218
1219         return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1220                                 get_pdu_int(ent), cmd);
1221 }
1222
1223 static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1224 {
1225         int ret;
1226         const struct blk_io_trace *t = te_blk_io_trace(ent);
1227
1228         ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1229         if (ret)
1230                 return trace_seq_putc(s, '\n');
1231         return ret;
1232 }
1233
1234 /*
1235  * struct tracer operations
1236  */
1237
1238 static void blk_tracer_print_header(struct seq_file *m)
1239 {
1240         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1241                 return;
1242         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1243                     "#  |     |     |           |   |   |\n");
1244 }
1245
1246 static void blk_tracer_start(struct trace_array *tr)
1247 {
1248         blk_tracer_enabled = true;
1249 }
1250
1251 static int blk_tracer_init(struct trace_array *tr)
1252 {
1253         blk_tr = tr;
1254         blk_tracer_start(tr);
1255         return 0;
1256 }
1257
1258 static void blk_tracer_stop(struct trace_array *tr)
1259 {
1260         blk_tracer_enabled = false;
1261 }
1262
1263 static void blk_tracer_reset(struct trace_array *tr)
1264 {
1265         blk_tracer_stop(tr);
1266 }
1267
1268 static const struct {
1269         const char *act[2];
1270         int        (*print)(struct trace_seq *s, const struct trace_entry *ent);
1271 } what2act[] = {
1272         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1273         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1274         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1275         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1276         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1277         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1278         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1279         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1280         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1281         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1282         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1283         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1284         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1285         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1286         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1287 };
1288
1289 static enum print_line_t print_one_line(struct trace_iterator *iter,
1290                                         bool classic)
1291 {
1292         struct trace_seq *s = &iter->seq;
1293         const struct blk_io_trace *t;
1294         u16 what;
1295         int ret;
1296         bool long_act;
1297         blk_log_action_t *log_action;
1298
1299         t          = te_blk_io_trace(iter->ent);
1300         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1301         long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1302         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1303
1304         if (t->action == BLK_TN_MESSAGE) {
1305                 ret = log_action(iter, long_act ? "message" : "m");
1306                 if (ret)
1307                         ret = blk_log_msg(s, iter->ent);
1308                 goto out;
1309         }
1310
1311         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1312                 ret = trace_seq_printf(s, "Unknown action %x\n", what);
1313         else {
1314                 ret = log_action(iter, what2act[what].act[long_act]);
1315                 if (ret)
1316                         ret = what2act[what].print(s, iter->ent);
1317         }
1318 out:
1319         return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1320 }
1321
1322 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1323                                                int flags)
1324 {
1325         return print_one_line(iter, false);
1326 }
1327
1328 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1329 {
1330         struct trace_seq *s = &iter->seq;
1331         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1332         const int offset = offsetof(struct blk_io_trace, sector);
1333         struct blk_io_trace old = {
1334                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1335                 .time     = iter->ts,
1336         };
1337
1338         if (!trace_seq_putmem(s, &old, offset))
1339                 return 0;
1340         return trace_seq_putmem(s, &t->sector,
1341                                 sizeof(old) - offset + t->pdu_len);
1342 }
1343
1344 static enum print_line_t
1345 blk_trace_event_print_binary(struct trace_iterator *iter, int flags)
1346 {
1347         return blk_trace_synthesize_old_trace(iter) ?
1348                         TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1349 }
1350
1351 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1352 {
1353         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1354                 return TRACE_TYPE_UNHANDLED;
1355
1356         return print_one_line(iter, true);
1357 }
1358
1359 static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
1360 {
1361         /* don't output context-info for blk_classic output */
1362         if (bit == TRACE_BLK_OPT_CLASSIC) {
1363                 if (set)
1364                         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1365                 else
1366                         trace_flags |= TRACE_ITER_CONTEXT_INFO;
1367         }
1368         return 0;
1369 }
1370
1371 static struct tracer blk_tracer __read_mostly = {
1372         .name           = "blk",
1373         .init           = blk_tracer_init,
1374         .reset          = blk_tracer_reset,
1375         .start          = blk_tracer_start,
1376         .stop           = blk_tracer_stop,
1377         .print_header   = blk_tracer_print_header,
1378         .print_line     = blk_tracer_print_line,
1379         .flags          = &blk_tracer_flags,
1380         .set_flag       = blk_tracer_set_flag,
1381 };
1382
1383 static struct trace_event trace_blk_event = {
1384         .type           = TRACE_BLK,
1385         .trace          = blk_trace_event_print,
1386         .binary         = blk_trace_event_print_binary,
1387 };
1388
1389 static int __init init_blk_tracer(void)
1390 {
1391         if (!register_ftrace_event(&trace_blk_event)) {
1392                 pr_warning("Warning: could not register block events\n");
1393                 return 1;
1394         }
1395
1396         if (register_tracer(&blk_tracer) != 0) {
1397                 pr_warning("Warning: could not register the block tracer\n");
1398                 unregister_ftrace_event(&trace_blk_event);
1399                 return 1;
1400         }
1401
1402         return 0;
1403 }
1404
1405 device_initcall(init_blk_tracer);
1406
1407 static int blk_trace_remove_queue(struct request_queue *q)
1408 {
1409         struct blk_trace *bt;
1410
1411         bt = xchg(&q->blk_trace, NULL);
1412         if (bt == NULL)
1413                 return -EINVAL;
1414
1415         if (atomic_dec_and_test(&blk_probes_ref))
1416                 blk_unregister_tracepoints();
1417
1418         blk_trace_free(bt);
1419         return 0;
1420 }
1421
1422 /*
1423  * Setup everything required to start tracing
1424  */
1425 static int blk_trace_setup_queue(struct request_queue *q,
1426                                  struct block_device *bdev)
1427 {
1428         struct blk_trace *old_bt, *bt = NULL;
1429         int ret = -ENOMEM;
1430
1431         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1432         if (!bt)
1433                 return -ENOMEM;
1434
1435         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1436         if (!bt->msg_data)
1437                 goto free_bt;
1438
1439         bt->dev = bdev->bd_dev;
1440         bt->act_mask = (u16)-1;
1441
1442         blk_trace_setup_lba(bt, bdev);
1443
1444         old_bt = xchg(&q->blk_trace, bt);
1445         if (old_bt != NULL) {
1446                 (void)xchg(&q->blk_trace, old_bt);
1447                 ret = -EBUSY;
1448                 goto free_bt;
1449         }
1450
1451         if (atomic_inc_return(&blk_probes_ref) == 1)
1452                 blk_register_tracepoints();
1453         return 0;
1454
1455 free_bt:
1456         blk_trace_free(bt);
1457         return ret;
1458 }
1459
1460 /*
1461  * sysfs interface to enable and configure tracing
1462  */
1463
1464 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1465                                          struct device_attribute *attr,
1466                                          char *buf);
1467 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1468                                           struct device_attribute *attr,
1469                                           const char *buf, size_t count);
1470 #define BLK_TRACE_DEVICE_ATTR(_name) \
1471         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1472                     sysfs_blk_trace_attr_show, \
1473                     sysfs_blk_trace_attr_store)
1474
1475 static BLK_TRACE_DEVICE_ATTR(enable);
1476 static BLK_TRACE_DEVICE_ATTR(act_mask);
1477 static BLK_TRACE_DEVICE_ATTR(pid);
1478 static BLK_TRACE_DEVICE_ATTR(start_lba);
1479 static BLK_TRACE_DEVICE_ATTR(end_lba);
1480
1481 static struct attribute *blk_trace_attrs[] = {
1482         &dev_attr_enable.attr,
1483         &dev_attr_act_mask.attr,
1484         &dev_attr_pid.attr,
1485         &dev_attr_start_lba.attr,
1486         &dev_attr_end_lba.attr,
1487         NULL
1488 };
1489
1490 struct attribute_group blk_trace_attr_group = {
1491         .name  = "trace",
1492         .attrs = blk_trace_attrs,
1493 };
1494
1495 static const struct {
1496         int mask;
1497         const char *str;
1498 } mask_maps[] = {
1499         { BLK_TC_READ,          "read"          },
1500         { BLK_TC_WRITE,         "write"         },
1501         { BLK_TC_BARRIER,       "barrier"       },
1502         { BLK_TC_SYNC,          "sync"          },
1503         { BLK_TC_QUEUE,         "queue"         },
1504         { BLK_TC_REQUEUE,       "requeue"       },
1505         { BLK_TC_ISSUE,         "issue"         },
1506         { BLK_TC_COMPLETE,      "complete"      },
1507         { BLK_TC_FS,            "fs"            },
1508         { BLK_TC_PC,            "pc"            },
1509         { BLK_TC_AHEAD,         "ahead"         },
1510         { BLK_TC_META,          "meta"          },
1511         { BLK_TC_DISCARD,       "discard"       },
1512         { BLK_TC_DRV_DATA,      "drv_data"      },
1513 };
1514
1515 static int blk_trace_str2mask(const char *str)
1516 {
1517         int i;
1518         int mask = 0;
1519         char *buf, *s, *token;
1520
1521         buf = kstrdup(str, GFP_KERNEL);
1522         if (buf == NULL)
1523                 return -ENOMEM;
1524         s = strstrip(buf);
1525
1526         while (1) {
1527                 token = strsep(&s, ",");
1528                 if (token == NULL)
1529                         break;
1530
1531                 if (*token == '\0')
1532                         continue;
1533
1534                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1535                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1536                                 mask |= mask_maps[i].mask;
1537                                 break;
1538                         }
1539                 }
1540                 if (i == ARRAY_SIZE(mask_maps)) {
1541                         mask = -EINVAL;
1542                         break;
1543                 }
1544         }
1545         kfree(buf);
1546
1547         return mask;
1548 }
1549
1550 static ssize_t blk_trace_mask2str(char *buf, int mask)
1551 {
1552         int i;
1553         char *p = buf;
1554
1555         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1556                 if (mask & mask_maps[i].mask) {
1557                         p += sprintf(p, "%s%s",
1558                                     (p == buf) ? "" : ",", mask_maps[i].str);
1559                 }
1560         }
1561         *p++ = '\n';
1562
1563         return p - buf;
1564 }
1565
1566 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1567 {
1568         if (bdev->bd_disk == NULL)
1569                 return NULL;
1570
1571         return bdev_get_queue(bdev);
1572 }
1573
1574 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1575                                          struct device_attribute *attr,
1576                                          char *buf)
1577 {
1578         struct hd_struct *p = dev_to_part(dev);
1579         struct request_queue *q;
1580         struct block_device *bdev;
1581         ssize_t ret = -ENXIO;
1582
1583         lock_kernel();
1584         bdev = bdget(part_devt(p));
1585         if (bdev == NULL)
1586                 goto out_unlock_kernel;
1587
1588         q = blk_trace_get_queue(bdev);
1589         if (q == NULL)
1590                 goto out_bdput;
1591
1592         mutex_lock(&bdev->bd_mutex);
1593
1594         if (attr == &dev_attr_enable) {
1595                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1596                 goto out_unlock_bdev;
1597         }
1598
1599         if (q->blk_trace == NULL)
1600                 ret = sprintf(buf, "disabled\n");
1601         else if (attr == &dev_attr_act_mask)
1602                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1603         else if (attr == &dev_attr_pid)
1604                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1605         else if (attr == &dev_attr_start_lba)
1606                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1607         else if (attr == &dev_attr_end_lba)
1608                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1609
1610 out_unlock_bdev:
1611         mutex_unlock(&bdev->bd_mutex);
1612 out_bdput:
1613         bdput(bdev);
1614 out_unlock_kernel:
1615         unlock_kernel();
1616         return ret;
1617 }
1618
1619 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1620                                           struct device_attribute *attr,
1621                                           const char *buf, size_t count)
1622 {
1623         struct block_device *bdev;
1624         struct request_queue *q;
1625         struct hd_struct *p;
1626         u64 value;
1627         ssize_t ret = -EINVAL;
1628
1629         if (count == 0)
1630                 goto out;
1631
1632         if (attr == &dev_attr_act_mask) {
1633                 if (sscanf(buf, "%llx", &value) != 1) {
1634                         /* Assume it is a list of trace category names */
1635                         ret = blk_trace_str2mask(buf);
1636                         if (ret < 0)
1637                                 goto out;
1638                         value = ret;
1639                 }
1640         } else if (sscanf(buf, "%llu", &value) != 1)
1641                 goto out;
1642
1643         ret = -ENXIO;
1644
1645         lock_kernel();
1646         p = dev_to_part(dev);
1647         bdev = bdget(part_devt(p));
1648         if (bdev == NULL)
1649                 goto out_unlock_kernel;
1650
1651         q = blk_trace_get_queue(bdev);
1652         if (q == NULL)
1653                 goto out_bdput;
1654
1655         mutex_lock(&bdev->bd_mutex);
1656
1657         if (attr == &dev_attr_enable) {
1658                 if (value)
1659                         ret = blk_trace_setup_queue(q, bdev);
1660                 else
1661                         ret = blk_trace_remove_queue(q);
1662                 goto out_unlock_bdev;
1663         }
1664
1665         ret = 0;
1666         if (q->blk_trace == NULL)
1667                 ret = blk_trace_setup_queue(q, bdev);
1668
1669         if (ret == 0) {
1670                 if (attr == &dev_attr_act_mask)
1671                         q->blk_trace->act_mask = value;
1672                 else if (attr == &dev_attr_pid)
1673                         q->blk_trace->pid = value;
1674                 else if (attr == &dev_attr_start_lba)
1675                         q->blk_trace->start_lba = value;
1676                 else if (attr == &dev_attr_end_lba)
1677                         q->blk_trace->end_lba = value;
1678         }
1679
1680 out_unlock_bdev:
1681         mutex_unlock(&bdev->bd_mutex);
1682 out_bdput:
1683         bdput(bdev);
1684 out_unlock_kernel:
1685         unlock_kernel();
1686 out:
1687         return ret ? ret : count;
1688 }
1689
1690 int blk_trace_init_sysfs(struct device *dev)
1691 {
1692         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1693 }
1694
1695 void blk_trace_remove_sysfs(struct device *dev)
1696 {
1697         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1698 }
1699
1700 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1701
1702 #ifdef CONFIG_EVENT_TRACING
1703
1704 void blk_dump_cmd(char *buf, struct request *rq)
1705 {
1706         int i, end;
1707         int len = rq->cmd_len;
1708         unsigned char *cmd = rq->cmd;
1709
1710         if (!blk_pc_request(rq)) {
1711                 buf[0] = '\0';
1712                 return;
1713         }
1714
1715         for (end = len - 1; end >= 0; end--)
1716                 if (cmd[end])
1717                         break;
1718         end++;
1719
1720         for (i = 0; i < len; i++) {
1721                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1722                 if (i == end && end != len - 1) {
1723                         sprintf(buf, " ..");
1724                         break;
1725                 }
1726         }
1727 }
1728
1729 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1730 {
1731         int i = 0;
1732
1733         if (rw & WRITE)
1734                 rwbs[i++] = 'W';
1735         else if (rw & 1 << BIO_RW_DISCARD)
1736                 rwbs[i++] = 'D';
1737         else if (bytes)
1738                 rwbs[i++] = 'R';
1739         else
1740                 rwbs[i++] = 'N';
1741
1742         if (rw & 1 << BIO_RW_AHEAD)
1743                 rwbs[i++] = 'A';
1744         if (rw & 1 << BIO_RW_BARRIER)
1745                 rwbs[i++] = 'B';
1746         if (rw & 1 << BIO_RW_SYNCIO)
1747                 rwbs[i++] = 'S';
1748         if (rw & 1 << BIO_RW_META)
1749                 rwbs[i++] = 'M';
1750
1751         rwbs[i] = '\0';
1752 }
1753
1754 void blk_fill_rwbs_rq(char *rwbs, struct request *rq)
1755 {
1756         int rw = rq->cmd_flags & 0x03;
1757         int bytes;
1758
1759         if (blk_discard_rq(rq))
1760                 rw |= (1 << BIO_RW_DISCARD);
1761
1762         bytes = blk_rq_bytes(rq);
1763
1764         blk_fill_rwbs(rwbs, rw, bytes);
1765 }
1766
1767 #endif /* CONFIG_EVENT_TRACING */
1768