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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                 return -EFAULT;
 545
 546         return 0;
 547 }
 548 EXPORT_SYMBOL_GPL(blk_trace_setup);
 549
 550 int blk_trace_startstop(struct request_queue *q, int start)
 551 {
 552         int ret;
 553         struct blk_trace *bt = q->blk_trace;
 554
 555         if (bt == NULL)
 556                 return -EINVAL;
 557
 558         /*
 559          * For starting a trace, we can transition from a setup or stopped
 560          * trace. For stopping a trace, the state must be running
 561          */
 562         ret = -EINVAL;
 563         if (start) {
 564                 if (bt->trace_state == Blktrace_setup ||
 565                     bt->trace_state == Blktrace_stopped) {
 566                         blktrace_seq++;
 567                         smp_mb();
 568                         bt->trace_state = Blktrace_running;
 569
 570                         trace_note_time(bt);
 571                         ret = 0;
 572                 }
 573         } else {
 574                 if (bt->trace_state == Blktrace_running) {
 575                         bt->trace_state = Blktrace_stopped;
 576                         relay_flush(bt->rchan);
 577                         ret = 0;
 578                 }
 579         }
 580
 581         return ret;
 582 }
 583 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 584
 585 /**
 586  * blk_trace_ioctl: - handle the ioctls associated with tracing
 587  * @bdev:       the block device
 588  * @cmd:        the ioctl cmd
 589  * @arg:        the argument data, if any
 590  *
 591  **/
 592 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 593 {
 594         struct request_queue *q;
 595         int ret, start = 0;
 596         char b[BDEVNAME_SIZE];
 597
 598         q = bdev_get_queue(bdev);
 599         if (!q)
 600                 return -ENXIO;
 601
 602         mutex_lock(&bdev->bd_mutex);
 603
 604         switch (cmd) {
 605         case BLKTRACESETUP:
 606                 bdevname(bdev, b);
 607                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 608                 break;
 609         case BLKTRACESTART:
 610                 start = 1;
 611         case BLKTRACESTOP:
 612                 ret = blk_trace_startstop(q, start);
 613                 break;
 614         case BLKTRACETEARDOWN:
 615                 ret = blk_trace_remove(q);
 616                 break;
 617         default:
 618                 ret = -ENOTTY;
 619                 break;
 620         }
 621
 622         mutex_unlock(&bdev->bd_mutex);
 623         return ret;
 624 }
 625
 626 /**
 627  * blk_trace_shutdown: - stop and cleanup trace structures
 628  * @q:    the request queue associated with the device
 629  *
 630  **/
 631 void blk_trace_shutdown(struct request_queue *q)
 632 {
 633         if (q->blk_trace) {
 634                 blk_trace_startstop(q, 0);
 635                 blk_trace_remove(q);
 636         }
 637 }
 638
 639 /*
 640  * blktrace probes
 641  */
 642
 643 /**
 644  * blk_add_trace_rq - Add a trace for a request oriented action
 645  * @q:          queue the io is for
 646  * @rq:         the source request
 647  * @what:       the action
 648  *
 649  * Description:
 650  *     Records an action against a request. Will log the bio offset + size.
 651  *
 652  **/
 653 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 654                                     u32 what)
 655 {
 656         struct blk_trace *bt = q->blk_trace;
 657         int rw = rq->cmd_flags & 0x03;
 658
 659         if (likely(!bt))
 660                 return;
 661
 662         if (blk_discard_rq(rq))
 663                 rw |= (1 << BIO_RW_DISCARD);
 664
 665         if (blk_pc_request(rq)) {
 666                 what |= BLK_TC_ACT(BLK_TC_PC);
 667                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), rw,
 668                                 what, rq->errors, rq->cmd_len, rq->cmd);
 669         } else  {
 670                 what |= BLK_TC_ACT(BLK_TC_FS);
 671                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), rw,
 672                                 what, rq->errors, 0, NULL);
 673         }
 674 }
 675
 676 static void blk_add_trace_rq_abort(struct request_queue *q, struct request *rq)
 677 {
 678         blk_add_trace_rq(q, rq, BLK_TA_ABORT);
 679 }
 680
 681 static void blk_add_trace_rq_insert(struct request_queue *q, struct request *rq)
 682 {
 683         blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 684 }
 685
 686 static void blk_add_trace_rq_issue(struct request_queue *q, struct request *rq)
 687 {
 688         blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
 689 }
 690
 691 static void blk_add_trace_rq_requeue(struct request_queue *q,
 692                                      struct request *rq)
 693 {
 694         blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
 695 }
 696
 697 static void blk_add_trace_rq_complete(struct request_queue *q,
 698                                       struct request *rq)
 699 {
 700         blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
 701 }
 702
 703 /**
 704  * blk_add_trace_bio - Add a trace for a bio oriented action
 705  * @q:          queue the io is for
 706  * @bio:        the source bio
 707  * @what:       the action
 708  *
 709  * Description:
 710  *     Records an action against a bio. Will log the bio offset + size.
 711  *
 712  **/
 713 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 714                                      u32 what)
 715 {
 716         struct blk_trace *bt = q->blk_trace;
 717
 718         if (likely(!bt))
 719                 return;
 720
 721         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
 722                         !bio_flagged(bio, BIO_UPTODATE), 0, NULL);
 723 }
 724
 725 static void blk_add_trace_bio_bounce(struct request_queue *q, struct bio *bio)
 726 {
 727         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE);
 728 }
 729
 730 static void blk_add_trace_bio_complete(struct request_queue *q, struct bio *bio)
 731 {
 732         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE);
 733 }
 734
 735 static void blk_add_trace_bio_backmerge(struct request_queue *q,
 736                                         struct bio *bio)
 737 {
 738         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
 739 }
 740
 741 static void blk_add_trace_bio_frontmerge(struct request_queue *q,
 742                                          struct bio *bio)
 743 {
 744         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
 745 }
 746
 747 static void blk_add_trace_bio_queue(struct request_queue *q, struct bio *bio)
 748 {
 749         blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
 750 }
 751
 752 static void blk_add_trace_getrq(struct request_queue *q,
 753                                 struct bio *bio, int rw)
 754 {
 755         if (bio)
 756                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ);
 757         else {
 758                 struct blk_trace *bt = q->blk_trace;
 759
 760                 if (bt)
 761                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
 762         }
 763 }
 764
 765
 766 static void blk_add_trace_sleeprq(struct request_queue *q,
 767                                   struct bio *bio, int rw)
 768 {
 769         if (bio)
 770                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ);
 771         else {
 772                 struct blk_trace *bt = q->blk_trace;
 773
 774                 if (bt)
 775                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
 776                                         0, 0, NULL);
 777         }
 778 }
 779
 780 static void blk_add_trace_plug(struct request_queue *q)
 781 {
 782         struct blk_trace *bt = q->blk_trace;
 783
 784         if (bt)
 785                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
 786 }
 787
 788 static void blk_add_trace_unplug_io(struct request_queue *q)
 789 {
 790         struct blk_trace *bt = q->blk_trace;
 791
 792         if (bt) {
 793                 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
 794                 __be64 rpdu = cpu_to_be64(pdu);
 795
 796                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_IO, 0,
 797                                 sizeof(rpdu), &rpdu);
 798         }
 799 }
 800
 801 static void blk_add_trace_unplug_timer(struct request_queue *q)
 802 {
 803         struct blk_trace *bt = q->blk_trace;
 804
 805         if (bt) {
 806                 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
 807                 __be64 rpdu = cpu_to_be64(pdu);
 808
 809                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_TIMER, 0,
 810                                 sizeof(rpdu), &rpdu);
 811         }
 812 }
 813
 814 static void blk_add_trace_split(struct request_queue *q, struct bio *bio,
 815                                 unsigned int pdu)
 816 {
 817         struct blk_trace *bt = q->blk_trace;
 818
 819         if (bt) {
 820                 __be64 rpdu = cpu_to_be64(pdu);
 821
 822                 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 823                                 BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
 824                                 sizeof(rpdu), &rpdu);
 825         }
 826 }
 827
 828 /**
 829  * blk_add_trace_remap - Add a trace for a remap operation
 830  * @q:          queue the io is for
 831  * @bio:        the source bio
 832  * @dev:        target device
 833  * @from:       source sector
 834  *
 835  * Description:
 836  *     Device mapper or raid target sometimes need to split a bio because
 837  *     it spans a stripe (or similar). Add a trace for that action.
 838  *
 839  **/
 840 static void blk_add_trace_remap(struct request_queue *q, struct bio *bio,
 841                                        dev_t dev, sector_t from)
 842 {
 843         struct blk_trace *bt = q->blk_trace;
 844         struct blk_io_trace_remap r;
 845
 846         if (likely(!bt))
 847                 return;
 848
 849         r.device_from = cpu_to_be32(dev);
 850         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
 851         r.sector_from = cpu_to_be64(from);
 852
 853         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 854                         BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE),
 855                         sizeof(r), &r);
 856 }
 857
 858 /**
 859  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
 860  * @q:          queue the io is for
 861  * @rq:         the source request
 862  * @dev:        target device
 863  * @from:       source sector
 864  *
 865  * Description:
 866  *     Device mapper remaps request to other devices.
 867  *     Add a trace for that action.
 868  *
 869  **/
 870 static void blk_add_trace_rq_remap(struct request_queue *q,
 871                                    struct request *rq, dev_t dev,
 872                                    sector_t from)
 873 {
 874         struct blk_trace *bt = q->blk_trace;
 875         struct blk_io_trace_remap r;
 876
 877         if (likely(!bt))
 878                 return;
 879
 880         r.device_from = cpu_to_be32(dev);
 881         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
 882         r.sector_from = cpu_to_be64(from);
 883
 884         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 885                         rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
 886                         sizeof(r), &r);
 887 }
 888
 889 /**
 890  * blk_add_driver_data - Add binary message with driver-specific data
 891  * @q:          queue the io is for
 892  * @rq:         io request
 893  * @data:       driver-specific data
 894  * @len:        length of driver-specific data
 895  *
 896  * Description:
 897  *     Some drivers might want to write driver-specific data per request.
 898  *
 899  **/
 900 void blk_add_driver_data(struct request_queue *q,
 901                          struct request *rq,
 902                          void *data, size_t len)
 903 {
 904         struct blk_trace *bt = q->blk_trace;
 905
 906         if (likely(!bt))
 907                 return;
 908
 909         if (blk_pc_request(rq))
 910                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
 911                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 912         else
 913                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
 914                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 915 }
 916 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 917
 918 static void blk_register_tracepoints(void)
 919 {
 920         int ret;
 921
 922         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort);
 923         WARN_ON(ret);
 924         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert);
 925         WARN_ON(ret);
 926         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue);
 927         WARN_ON(ret);
 928         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue);
 929         WARN_ON(ret);
 930         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete);
 931         WARN_ON(ret);
 932         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce);
 933         WARN_ON(ret);
 934         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete);
 935         WARN_ON(ret);
 936         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
 937         WARN_ON(ret);
 938         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
 939         WARN_ON(ret);
 940         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue);
 941         WARN_ON(ret);
 942         ret = register_trace_block_getrq(blk_add_trace_getrq);
 943         WARN_ON(ret);
 944         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq);
 945         WARN_ON(ret);
 946         ret = register_trace_block_plug(blk_add_trace_plug);
 947         WARN_ON(ret);
 948         ret = register_trace_block_unplug_timer(blk_add_trace_unplug_timer);
 949         WARN_ON(ret);
 950         ret = register_trace_block_unplug_io(blk_add_trace_unplug_io);
 951         WARN_ON(ret);
 952         ret = register_trace_block_split(blk_add_trace_split);
 953         WARN_ON(ret);
 954         ret = register_trace_block_remap(blk_add_trace_remap);
 955         WARN_ON(ret);
 956         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap);
 957         WARN_ON(ret);
 958 }
 959
 960 static void blk_unregister_tracepoints(void)
 961 {
 962         unregister_trace_block_rq_remap(blk_add_trace_rq_remap);
 963         unregister_trace_block_remap(blk_add_trace_remap);
 964         unregister_trace_block_split(blk_add_trace_split);
 965         unregister_trace_block_unplug_io(blk_add_trace_unplug_io);
 966         unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer);
 967         unregister_trace_block_plug(blk_add_trace_plug);
 968         unregister_trace_block_sleeprq(blk_add_trace_sleeprq);
 969         unregister_trace_block_getrq(blk_add_trace_getrq);
 970         unregister_trace_block_bio_queue(blk_add_trace_bio_queue);
 971         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
 972         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
 973         unregister_trace_block_bio_complete(blk_add_trace_bio_complete);
 974         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce);
 975         unregister_trace_block_rq_complete(blk_add_trace_rq_complete);
 976         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue);
 977         unregister_trace_block_rq_issue(blk_add_trace_rq_issue);
 978         unregister_trace_block_rq_insert(blk_add_trace_rq_insert);
 979         unregister_trace_block_rq_abort(blk_add_trace_rq_abort);
 980
 981         tracepoint_synchronize_unregister();
 982 }
 983
 984 /*
 985  * struct blk_io_tracer formatting routines
 986  */
 987
 988 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
 989 {
 990         int i = 0;
 991         int tc = t->action >> BLK_TC_SHIFT;
 992
 993         if (t->action == BLK_TN_MESSAGE) {
 994                 rwbs[i++] = 'N';
 995                 goto out;
 996         }
 997
 998         if (tc & BLK_TC_DISCARD)
 999                 rwbs[i++] = 'D';
1000         else if (tc & BLK_TC_WRITE)
1001                 rwbs[i++] = 'W';
1002         else if (t->bytes)
1003                 rwbs[i++] = 'R';
1004         else
1005                 rwbs[i++] = 'N';
1006
1007         if (tc & BLK_TC_AHEAD)
1008                 rwbs[i++] = 'A';
1009         if (tc & BLK_TC_BARRIER)
1010                 rwbs[i++] = 'B';
1011         if (tc & BLK_TC_SYNC)
1012                 rwbs[i++] = 'S';
1013         if (tc & BLK_TC_META)
1014                 rwbs[i++] = 'M';
1015 out:
1016         rwbs[i] = '\0';
1017 }
1018
1019 static inline
1020 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1021 {
1022         return (const struct blk_io_trace *)ent;
1023 }
1024
1025 static inline const void *pdu_start(const struct trace_entry *ent)
1026 {
1027         return te_blk_io_trace(ent) + 1;
1028 }
1029
1030 static inline u32 t_action(const struct trace_entry *ent)
1031 {
1032         return te_blk_io_trace(ent)->action;
1033 }
1034
1035 static inline u32 t_bytes(const struct trace_entry *ent)
1036 {
1037         return te_blk_io_trace(ent)->bytes;
1038 }
1039
1040 static inline u32 t_sec(const struct trace_entry *ent)
1041 {
1042         return te_blk_io_trace(ent)->bytes >> 9;
1043 }
1044
1045 static inline unsigned long long t_sector(const struct trace_entry *ent)
1046 {
1047         return te_blk_io_trace(ent)->sector;
1048 }
1049
1050 static inline __u16 t_error(const struct trace_entry *ent)
1051 {
1052         return te_blk_io_trace(ent)->error;
1053 }
1054
1055 static __u64 get_pdu_int(const struct trace_entry *ent)
1056 {
1057         const __u64 *val = pdu_start(ent);
1058         return be64_to_cpu(*val);
1059 }
1060
1061 static void get_pdu_remap(const struct trace_entry *ent,
1062                           struct blk_io_trace_remap *r)
1063 {
1064         const struct blk_io_trace_remap *__r = pdu_start(ent);
1065         __u64 sector_from = __r->sector_from;
1066
1067         r->device_from = be32_to_cpu(__r->device_from);
1068         r->device_to   = be32_to_cpu(__r->device_to);
1069         r->sector_from = be64_to_cpu(sector_from);
1070 }
1071
1072 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1073
1074 static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1075 {
1076         char rwbs[6];
1077         unsigned long long ts  = iter->ts;
1078         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1079         unsigned secs          = (unsigned long)ts;
1080         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1081
1082         fill_rwbs(rwbs, t);
1083
1084         return trace_seq_printf(&iter->seq,
1085                                 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1086                                 MAJOR(t->device), MINOR(t->device), iter->cpu,
1087                                 secs, nsec_rem, iter->ent->pid, act, rwbs);
1088 }
1089
1090 static int blk_log_action(struct trace_iterator *iter, const char *act)
1091 {
1092         char rwbs[6];
1093         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1094
1095         fill_rwbs(rwbs, t);
1096         return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1097                                 MAJOR(t->device), MINOR(t->device), act, rwbs);
1098 }
1099
1100 static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1101 {
1102         const unsigned char *pdu_buf;
1103         int pdu_len;
1104         int i, end, ret;
1105
1106         pdu_buf = pdu_start(ent);
1107         pdu_len = te_blk_io_trace(ent)->pdu_len;
1108
1109         if (!pdu_len)
1110                 return 1;
1111
1112         /* find the last zero that needs to be printed */
1113         for (end = pdu_len - 1; end >= 0; end--)
1114                 if (pdu_buf[end])
1115                         break;
1116         end++;
1117
1118         if (!trace_seq_putc(s, '('))
1119                 return 0;
1120
1121         for (i = 0; i < pdu_len; i++) {
1122
1123                 ret = trace_seq_printf(s, "%s%02x",
1124                                        i == 0 ? "" : " ", pdu_buf[i]);
1125                 if (!ret)
1126                         return ret;
1127
1128                 /*
1129                  * stop when the rest is just zeroes and indicate so
1130                  * with a ".." appended
1131                  */
1132                 if (i == end && end != pdu_len - 1)
1133                         return trace_seq_puts(s, " ..) ");
1134         }
1135
1136         return trace_seq_puts(s, ") ");
1137 }
1138
1139 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1140 {
1141         char cmd[TASK_COMM_LEN];
1142
1143         trace_find_cmdline(ent->pid, cmd);
1144
1145         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1146                 int ret;
1147
1148                 ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1149                 if (!ret)
1150                         return 0;
1151                 ret = blk_log_dump_pdu(s, ent);
1152                 if (!ret)
1153                         return 0;
1154                 return trace_seq_printf(s, "[%s]\n", cmd);
1155         } else {
1156                 if (t_sec(ent))
1157                         return trace_seq_printf(s, "%llu + %u [%s]\n",
1158                                                 t_sector(ent), t_sec(ent), cmd);
1159                 return trace_seq_printf(s, "[%s]\n", cmd);
1160         }
1161 }
1162
1163 static int blk_log_with_error(struct trace_seq *s,
1164                               const struct trace_entry *ent)
1165 {
1166         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1167                 int ret;
1168
1169                 ret = blk_log_dump_pdu(s, ent);
1170                 if (ret)
1171                         return trace_seq_printf(s, "[%d]\n", t_error(ent));
1172                 return 0;
1173         } else {
1174                 if (t_sec(ent))
1175                         return trace_seq_printf(s, "%llu + %u [%d]\n",
1176                                                 t_sector(ent),
1177                                                 t_sec(ent), t_error(ent));
1178                 return trace_seq_printf(s, "%llu [%d]\n",
1179                                         t_sector(ent), t_error(ent));
1180         }
1181 }
1182
1183 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1184 {
1185         struct blk_io_trace_remap r = { .device_from = 0, };
1186
1187         get_pdu_remap(ent, &r);
1188         return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1189                                 t_sector(ent), t_sec(ent),
1190                                 MAJOR(r.device_from), MINOR(r.device_from),
1191                                 (unsigned long long)r.sector_from);
1192 }
1193
1194 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1195 {
1196         char cmd[TASK_COMM_LEN];
1197
1198         trace_find_cmdline(ent->pid, cmd);
1199
1200         return trace_seq_printf(s, "[%s]\n", cmd);
1201 }
1202
1203 static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1204 {
1205         char cmd[TASK_COMM_LEN];
1206
1207         trace_find_cmdline(ent->pid, cmd);
1208
1209         return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1210 }
1211
1212 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1213 {
1214         char cmd[TASK_COMM_LEN];
1215
1216         trace_find_cmdline(ent->pid, cmd);
1217
1218         return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1219                                 get_pdu_int(ent), cmd);
1220 }
1221
1222 static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1223 {
1224         int ret;
1225         const struct blk_io_trace *t = te_blk_io_trace(ent);
1226
1227         ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1228         if (ret)
1229                 return trace_seq_putc(s, '\n');
1230         return ret;
1231 }
1232
1233 /*
1234  * struct tracer operations
1235  */
1236
1237 static void blk_tracer_print_header(struct seq_file *m)
1238 {
1239         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1240                 return;
1241         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1242                     "#  |     |     |           |   |   |\n");
1243 }
1244
1245 static void blk_tracer_start(struct trace_array *tr)
1246 {
1247         blk_tracer_enabled = true;
1248 }
1249
1250 static int blk_tracer_init(struct trace_array *tr)
1251 {
1252         blk_tr = tr;
1253         blk_tracer_start(tr);
1254         return 0;
1255 }
1256
1257 static void blk_tracer_stop(struct trace_array *tr)
1258 {
1259         blk_tracer_enabled = false;
1260 }
1261
1262 static void blk_tracer_reset(struct trace_array *tr)
1263 {
1264         blk_tracer_stop(tr);
1265 }
1266
1267 static const struct {
1268         const char *act[2];
1269         int        (*print)(struct trace_seq *s, const struct trace_entry *ent);
1270 } what2act[] = {
1271         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1272         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1273         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1274         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1275         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1276         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1277         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1278         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1279         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1280         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1281         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1282         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1283         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1284         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1285         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1286 };
1287
1288 static enum print_line_t print_one_line(struct trace_iterator *iter,
1289                                         bool classic)
1290 {
1291         struct trace_seq *s = &iter->seq;
1292         const struct blk_io_trace *t;
1293         u16 what;
1294         int ret;
1295         bool long_act;
1296         blk_log_action_t *log_action;
1297
1298         t          = te_blk_io_trace(iter->ent);
1299         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1300         long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1301         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1302
1303         if (t->action == BLK_TN_MESSAGE) {
1304                 ret = log_action(iter, long_act ? "message" : "m");
1305                 if (ret)
1306                         ret = blk_log_msg(s, iter->ent);
1307                 goto out;
1308         }
1309
1310         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1311                 ret = trace_seq_printf(s, "Unknown action %x\n", what);
1312         else {
1313                 ret = log_action(iter, what2act[what].act[long_act]);
1314                 if (ret)
1315                         ret = what2act[what].print(s, iter->ent);
1316         }
1317 out:
1318         return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1319 }
1320
1321 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1322                                                int flags)
1323 {
1324         return print_one_line(iter, false);
1325 }
1326
1327 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1328 {
1329         struct trace_seq *s = &iter->seq;
1330         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1331         const int offset = offsetof(struct blk_io_trace, sector);
1332         struct blk_io_trace old = {
1333                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1334                 .time     = iter->ts,
1335         };
1336
1337         if (!trace_seq_putmem(s, &old, offset))
1338                 return 0;
1339         return trace_seq_putmem(s, &t->sector,
1340                                 sizeof(old) - offset + t->pdu_len);
1341 }
1342
1343 static enum print_line_t
1344 blk_trace_event_print_binary(struct trace_iterator *iter, int flags)
1345 {
1346         return blk_trace_synthesize_old_trace(iter) ?
1347                         TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1348 }
1349
1350 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1351 {
1352         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1353                 return TRACE_TYPE_UNHANDLED;
1354
1355         return print_one_line(iter, true);
1356 }
1357
1358 static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
1359 {
1360         /* don't output context-info for blk_classic output */
1361         if (bit == TRACE_BLK_OPT_CLASSIC) {
1362                 if (set)
1363                         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1364                 else
1365                         trace_flags |= TRACE_ITER_CONTEXT_INFO;
1366         }
1367         return 0;
1368 }
1369
1370 static struct tracer blk_tracer __read_mostly = {
1371         .name           = "blk",
1372         .init           = blk_tracer_init,
1373         .reset          = blk_tracer_reset,
1374         .start          = blk_tracer_start,
1375         .stop           = blk_tracer_stop,
1376         .print_header   = blk_tracer_print_header,
1377         .print_line     = blk_tracer_print_line,
1378         .flags          = &blk_tracer_flags,
1379         .set_flag       = blk_tracer_set_flag,
1380 };
1381
1382 static struct trace_event trace_blk_event = {
1383         .type           = TRACE_BLK,
1384         .trace          = blk_trace_event_print,
1385         .binary         = blk_trace_event_print_binary,
1386 };
1387
1388 static int __init init_blk_tracer(void)
1389 {
1390         if (!register_ftrace_event(&trace_blk_event)) {
1391                 pr_warning("Warning: could not register block events\n");
1392                 return 1;
1393         }
1394
1395         if (register_tracer(&blk_tracer) != 0) {
1396                 pr_warning("Warning: could not register the block tracer\n");
1397                 unregister_ftrace_event(&trace_blk_event);
1398                 return 1;
1399         }
1400
1401         return 0;
1402 }
1403
1404 device_initcall(init_blk_tracer);
1405
1406 static int blk_trace_remove_queue(struct request_queue *q)
1407 {
1408         struct blk_trace *bt;
1409
1410         bt = xchg(&q->blk_trace, NULL);
1411         if (bt == NULL)
1412                 return -EINVAL;
1413
1414         if (atomic_dec_and_test(&blk_probes_ref))
1415                 blk_unregister_tracepoints();
1416
1417         blk_trace_free(bt);
1418         return 0;
1419 }
1420
1421 /*
1422  * Setup everything required to start tracing
1423  */
1424 static int blk_trace_setup_queue(struct request_queue *q,
1425                                  struct block_device *bdev)
1426 {
1427         struct blk_trace *old_bt, *bt = NULL;
1428         int ret = -ENOMEM;
1429
1430         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1431         if (!bt)
1432                 return -ENOMEM;
1433
1434         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1435         if (!bt->msg_data)
1436                 goto free_bt;
1437
1438         bt->dev = bdev->bd_dev;
1439         bt->act_mask = (u16)-1;
1440
1441         blk_trace_setup_lba(bt, bdev);
1442
1443         old_bt = xchg(&q->blk_trace, bt);
1444         if (old_bt != NULL) {
1445                 (void)xchg(&q->blk_trace, old_bt);
1446                 ret = -EBUSY;
1447                 goto free_bt;
1448         }
1449
1450         if (atomic_inc_return(&blk_probes_ref) == 1)
1451                 blk_register_tracepoints();
1452         return 0;
1453
1454 free_bt:
1455         blk_trace_free(bt);
1456         return ret;
1457 }
1458
1459 /*
1460  * sysfs interface to enable and configure tracing
1461  */
1462
1463 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1464                                          struct device_attribute *attr,
1465                                          char *buf);
1466 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1467                                           struct device_attribute *attr,
1468                                           const char *buf, size_t count);
1469 #define BLK_TRACE_DEVICE_ATTR(_name) \
1470         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1471                     sysfs_blk_trace_attr_show, \
1472                     sysfs_blk_trace_attr_store)
1473
1474 static BLK_TRACE_DEVICE_ATTR(enable);
1475 static BLK_TRACE_DEVICE_ATTR(act_mask);
1476 static BLK_TRACE_DEVICE_ATTR(pid);
1477 static BLK_TRACE_DEVICE_ATTR(start_lba);
1478 static BLK_TRACE_DEVICE_ATTR(end_lba);
1479
1480 static struct attribute *blk_trace_attrs[] = {
1481         &dev_attr_enable.attr,
1482         &dev_attr_act_mask.attr,
1483         &dev_attr_pid.attr,
1484         &dev_attr_start_lba.attr,
1485         &dev_attr_end_lba.attr,
1486         NULL
1487 };
1488
1489 struct attribute_group blk_trace_attr_group = {
1490         .name  = "trace",
1491         .attrs = blk_trace_attrs,
1492 };
1493
1494 static const struct {
1495         int mask;
1496         const char *str;
1497 } mask_maps[] = {
1498         { BLK_TC_READ,          "read"          },
1499         { BLK_TC_WRITE,         "write"         },
1500         { BLK_TC_BARRIER,       "barrier"       },
1501         { BLK_TC_SYNC,          "sync"          },
1502         { BLK_TC_QUEUE,         "queue"         },
1503         { BLK_TC_REQUEUE,       "requeue"       },
1504         { BLK_TC_ISSUE,         "issue"         },
1505         { BLK_TC_COMPLETE,      "complete"      },
1506         { BLK_TC_FS,            "fs"            },
1507         { BLK_TC_PC,            "pc"            },
1508         { BLK_TC_AHEAD,         "ahead"         },
1509         { BLK_TC_META,          "meta"          },
1510         { BLK_TC_DISCARD,       "discard"       },
1511         { BLK_TC_DRV_DATA,      "drv_data"      },
1512 };
1513
1514 static int blk_trace_str2mask(const char *str)
1515 {
1516         int i;
1517         int mask = 0;
1518         char *buf, *s, *token;
1519
1520         buf = kstrdup(str, GFP_KERNEL);
1521         if (buf == NULL)
1522                 return -ENOMEM;
1523         s = strstrip(buf);
1524
1525         while (1) {
1526                 token = strsep(&s, ",");
1527                 if (token == NULL)
1528                         break;
1529
1530                 if (*token == '\0')
1531                         continue;
1532
1533                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1534                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1535                                 mask |= mask_maps[i].mask;
1536                                 break;
1537                         }
1538                 }
1539                 if (i == ARRAY_SIZE(mask_maps)) {
1540                         mask = -EINVAL;
1541                         break;
1542                 }
1543         }
1544         kfree(buf);
1545
1546         return mask;
1547 }
1548
1549 static ssize_t blk_trace_mask2str(char *buf, int mask)
1550 {
1551         int i;
1552         char *p = buf;
1553
1554         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1555                 if (mask & mask_maps[i].mask) {
1556                         p += sprintf(p, "%s%s",
1557                                     (p == buf) ? "" : ",", mask_maps[i].str);
1558                 }
1559         }
1560         *p++ = '\n';
1561
1562         return p - buf;
1563 }
1564
1565 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1566 {
1567         if (bdev->bd_disk == NULL)
1568                 return NULL;
1569
1570         return bdev_get_queue(bdev);
1571 }
1572
1573 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1574                                          struct device_attribute *attr,
1575                                          char *buf)
1576 {
1577         struct hd_struct *p = dev_to_part(dev);
1578         struct request_queue *q;
1579         struct block_device *bdev;
1580         ssize_t ret = -ENXIO;
1581
1582         lock_kernel();
1583         bdev = bdget(part_devt(p));
1584         if (bdev == NULL)
1585                 goto out_unlock_kernel;
1586
1587         q = blk_trace_get_queue(bdev);
1588         if (q == NULL)
1589                 goto out_bdput;
1590
1591         mutex_lock(&bdev->bd_mutex);
1592
1593         if (attr == &dev_attr_enable) {
1594                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1595                 goto out_unlock_bdev;
1596         }
1597
1598         if (q->blk_trace == NULL)
1599                 ret = sprintf(buf, "disabled\n");
1600         else if (attr == &dev_attr_act_mask)
1601                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1602         else if (attr == &dev_attr_pid)
1603                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1604         else if (attr == &dev_attr_start_lba)
1605                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1606         else if (attr == &dev_attr_end_lba)
1607                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1608
1609 out_unlock_bdev:
1610         mutex_unlock(&bdev->bd_mutex);
1611 out_bdput:
1612         bdput(bdev);
1613 out_unlock_kernel:
1614         unlock_kernel();
1615         return ret;
1616 }
1617
1618 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1619                                           struct device_attribute *attr,
1620                                           const char *buf, size_t count)
1621 {
1622         struct block_device *bdev;
1623         struct request_queue *q;
1624         struct hd_struct *p;
1625         u64 value;
1626         ssize_t ret = -EINVAL;
1627
1628         if (count == 0)
1629                 goto out;
1630
1631         if (attr == &dev_attr_act_mask) {
1632                 if (sscanf(buf, "%llx", &value) != 1) {
1633                         /* Assume it is a list of trace category names */
1634                         ret = blk_trace_str2mask(buf);
1635                         if (ret < 0)
1636                                 goto out;
1637                         value = ret;
1638                 }
1639         } else if (sscanf(buf, "%llu", &value) != 1)
1640                 goto out;
1641
1642         ret = -ENXIO;
1643
1644         lock_kernel();
1645         p = dev_to_part(dev);
1646         bdev = bdget(part_devt(p));
1647         if (bdev == NULL)
1648                 goto out_unlock_kernel;
1649
1650         q = blk_trace_get_queue(bdev);
1651         if (q == NULL)
1652                 goto out_bdput;
1653
1654         mutex_lock(&bdev->bd_mutex);
1655
1656         if (attr == &dev_attr_enable) {
1657                 if (value)
1658                         ret = blk_trace_setup_queue(q, bdev);
1659                 else
1660                         ret = blk_trace_remove_queue(q);
1661                 goto out_unlock_bdev;
1662         }
1663
1664         ret = 0;
1665         if (q->blk_trace == NULL)
1666                 ret = blk_trace_setup_queue(q, bdev);
1667
1668         if (ret == 0) {
1669                 if (attr == &dev_attr_act_mask)
1670                         q->blk_trace->act_mask = value;
1671                 else if (attr == &dev_attr_pid)
1672                         q->blk_trace->pid = value;
1673                 else if (attr == &dev_attr_start_lba)
1674                         q->blk_trace->start_lba = value;
1675                 else if (attr == &dev_attr_end_lba)
1676                         q->blk_trace->end_lba = value;
1677         }
1678
1679 out_unlock_bdev:
1680         mutex_unlock(&bdev->bd_mutex);
1681 out_bdput:
1682         bdput(bdev);
1683 out_unlock_kernel:
1684         unlock_kernel();
1685 out:
1686         return ret ? ret : count;
1687 }
1688
1689 int blk_trace_init_sysfs(struct device *dev)
1690 {
1691         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1692 }
1693
1694 void blk_trace_remove_sysfs(struct device *dev)
1695 {
1696         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1697 }
1698
1699 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1700
1701 #ifdef CONFIG_EVENT_TRACING
1702
1703 void blk_dump_cmd(char *buf, struct request *rq)
1704 {
1705         int i, end;
1706         int len = rq->cmd_len;
1707         unsigned char *cmd = rq->cmd;
1708
1709         if (!blk_pc_request(rq)) {
1710                 buf[0] = '\0';
1711                 return;
1712         }
1713
1714         for (end = len - 1; end >= 0; end--)
1715                 if (cmd[end])
1716                         break;
1717         end++;
1718
1719         for (i = 0; i < len; i++) {
1720                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1721                 if (i == end && end != len - 1) {
1722                         sprintf(buf, " ..");
1723                         break;
1724                 }
1725         }
1726 }
1727
1728 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1729 {
1730         int i = 0;
1731
1732         if (rw & WRITE)
1733                 rwbs[i++] = 'W';
1734         else if (rw & 1 << BIO_RW_DISCARD)
1735                 rwbs[i++] = 'D';
1736         else if (bytes)
1737                 rwbs[i++] = 'R';
1738         else
1739                 rwbs[i++] = 'N';
1740
1741         if (rw & 1 << BIO_RW_AHEAD)
1742                 rwbs[i++] = 'A';
1743         if (rw & 1 << BIO_RW_BARRIER)
1744                 rwbs[i++] = 'B';
1745         if (rw & 1 << BIO_RW_SYNCIO)
1746                 rwbs[i++] = 'S';
1747         if (rw & 1 << BIO_RW_META)
1748                 rwbs[i++] = 'M';
1749
1750         rwbs[i] = '\0';
1751 }
1752
1753 void blk_fill_rwbs_rq(char *rwbs, struct request *rq)
1754 {
1755         int rw = rq->cmd_flags & 0x03;
1756         int bytes;
1757
1758         if (blk_discard_rq(rq))
1759                 rw |= (1 << BIO_RW_DISCARD);
1760
1761         bytes = blk_rq_bytes(rq);
1762
1763         blk_fill_rwbs(rwbs, rw, bytes);
1764 }
1765
1766 #endif /* CONFIG_EVENT_TRACING */
1767