kernel/trace/blktrace.c

   1 /*
   2  * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  16  *
  17  */
  18 #include <linux/kernel.h>
  19 #include <linux/blkdev.h>
  20 #include <linux/blktrace_api.h>
  21 #include <linux/percpu.h>
  22 #include <linux/init.h>
  23 #include <linux/mutex.h>
  24 #include <linux/slab.h>
  25 #include <linux/debugfs.h>
  26 #include <linux/smp_lock.h>
  27 #include <linux/time.h>
  28 #include <linux/uaccess.h>
  29
  30 #include <trace/events/block.h>
  31
  32 #include "trace_output.h"
  33
  34 #ifdef CONFIG_BLK_DEV_IO_TRACE
  35
  36 static unsigned int blktrace_seq __read_mostly = 1;
  37
  38 static struct trace_array *blk_tr;
  39 static bool blk_tracer_enabled __read_mostly;
  40
  41 /* Select an alternative, minimalistic output than the original one */
  42 #define TRACE_BLK_OPT_CLASSIC   0x1
  43
  44 static struct tracer_opt blk_tracer_opts[] = {
  45         /* Default disable the minimalistic output */
  46         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
  47         { }
  48 };
  49
  50 static struct tracer_flags blk_tracer_flags = {
  51         .val  = 0,
  52         .opts = blk_tracer_opts,
  53 };
  54
  55 /* Global reference count of probes */
  56 static atomic_t blk_probes_ref = ATOMIC_INIT(0);
  57
  58 static void blk_register_tracepoints(void);
  59 static void blk_unregister_tracepoints(void);
  60
  61 /*
  62  * Send out a notify message.
  63  */
  64 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
  65                        const void *data, size_t len)
  66 {
  67         struct blk_io_trace *t;
  68         struct ring_buffer_event *event = NULL;
  69         struct ring_buffer *buffer = NULL;
  70         int pc = 0;
  71         int cpu = smp_processor_id();
  72         bool blk_tracer = blk_tracer_enabled;
  73
  74         if (blk_tracer) {
  75                 buffer = blk_tr->buffer;
  76                 pc = preempt_count();
  77                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
  78                                                   sizeof(*t) + len,
  79                                                   0, pc);
  80                 if (!event)
  81                         return;
  82                 t = ring_buffer_event_data(event);
  83                 goto record_it;
  84         }
  85
  86         if (!bt->rchan)
  87                 return;
  88
  89         t = relay_reserve(bt->rchan, sizeof(*t) + len);
  90         if (t) {
  91                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
  92                 t->time = ktime_to_ns(ktime_get());
  93 record_it:
  94                 t->device = bt->dev;
  95                 t->action = action;
  96                 t->pid = pid;
  97                 t->cpu = cpu;
  98                 t->pdu_len = len;
  99                 memcpy((void *) t + sizeof(*t), data, len);
 100
 101                 if (blk_tracer)
 102                         trace_buffer_unlock_commit(buffer, event, 0, pc);
 103         }
 104 }
 105
 106 /*
 107  * Send out a notify for this process, if we haven't done so since a trace
 108  * started
 109  */
 110 static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
 111 {
 112         tsk->btrace_seq = blktrace_seq;
 113         trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));
 114 }
 115
 116 static void trace_note_time(struct blk_trace *bt)
 117 {
 118         struct timespec now;
 119         unsigned long flags;
 120         u32 words[2];
 121
 122         getnstimeofday(&now);
 123         words[0] = now.tv_sec;
 124         words[1] = now.tv_nsec;
 125
 126         local_irq_save(flags);
 127         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
 128         local_irq_restore(flags);
 129 }
 130
 131 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 132 {
 133         int n;
 134         va_list args;
 135         unsigned long flags;
 136         char *buf;
 137
 138         if (unlikely(bt->trace_state != Blktrace_running &&
 139                      !blk_tracer_enabled))
 140                 return;
 141
 142         local_irq_save(flags);
 143         buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
 144         va_start(args, fmt);
 145         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 146         va_end(args);
 147
 148         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
 149         local_irq_restore(flags);
 150 }
 151 EXPORT_SYMBOL_GPL(__trace_note_message);
 152
 153 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
 154                          pid_t pid)
 155 {
 156         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
 157                 return 1;
 158         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
 159                 return 1;
 160         if (bt->pid && pid != bt->pid)
 161                 return 1;
 162
 163         return 0;
 164 }
 165
 166 /*
 167  * Data direction bit lookup
 168  */
 169 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
 170                                  BLK_TC_ACT(BLK_TC_WRITE) };
 171
 172 /* The ilog2() calls fall out because they're constant */
 173 #define MASK_TC_BIT(rw, __name) ((rw & (1 << BIO_RW_ ## __name)) << \
 174           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - BIO_RW_ ## __name))
 175
 176 /*
 177  * The worker for the various blk_add_trace*() types. Fills out a
 178  * blk_io_trace structure and places it in a per-cpu subbuffer.
 179  */
 180 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 181                      int rw, u32 what, int error, int pdu_len, void *pdu_data)
 182 {
 183         struct task_struct *tsk = current;
 184         struct ring_buffer_event *event = NULL;
 185         struct ring_buffer *buffer = NULL;
 186         struct blk_io_trace *t;
 187         unsigned long flags = 0;
 188         unsigned long *sequence;
 189         pid_t pid;
 190         int cpu, pc = 0;
 191         bool blk_tracer = blk_tracer_enabled;
 192
 193         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
 194                 return;
 195
 196         what |= ddir_act[rw & WRITE];
 197         what |= MASK_TC_BIT(rw, BARRIER);
 198         what |= MASK_TC_BIT(rw, SYNCIO);
 199         what |= MASK_TC_BIT(rw, AHEAD);
 200         what |= MASK_TC_BIT(rw, META);
 201         what |= MASK_TC_BIT(rw, DISCARD);
 202
 203         pid = tsk->pid;
 204         if (act_log_check(bt, what, sector, pid))
 205                 return;
 206         cpu = raw_smp_processor_id();
 207
 208         if (blk_tracer) {
 209                 tracing_record_cmdline(current);
 210
 211                 buffer = blk_tr->buffer;
 212                 pc = preempt_count();
 213                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 214                                                   sizeof(*t) + pdu_len,
 215                                                   0, pc);
 216                 if (!event)
 217                         return;
 218                 t = ring_buffer_event_data(event);
 219                 goto record_it;
 220         }
 221
 222         /*
 223          * A word about the locking here - we disable interrupts to reserve
 224          * some space in the relay per-cpu buffer, to prevent an irq
 225          * from coming in and stepping on our toes.
 226          */
 227         local_irq_save(flags);
 228
 229         if (unlikely(tsk->btrace_seq != blktrace_seq))
 230                 trace_note_tsk(bt, tsk);
 231
 232         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
 233         if (t) {
 234                 sequence = per_cpu_ptr(bt->sequence, cpu);
 235
 236                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 237                 t->sequence = ++(*sequence);
 238                 t->time = ktime_to_ns(ktime_get());
 239 record_it:
 240                 /*
 241                  * These two are not needed in ftrace as they are in the
 242                  * generic trace_entry, filled by tracing_generic_entry_update,
 243                  * but for the trace_event->bin() synthesizer benefit we do it
 244                  * here too.
 245                  */
 246                 t->cpu = cpu;
 247                 t->pid = pid;
 248
 249                 t->sector = sector;
 250                 t->bytes = bytes;
 251                 t->action = what;
 252                 t->device = bt->dev;
 253                 t->error = error;
 254                 t->pdu_len = pdu_len;
 255
 256                 if (pdu_len)
 257                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
 258
 259                 if (blk_tracer) {
 260                         trace_buffer_unlock_commit(buffer, event, 0, pc);
 261                         return;
 262                 }
 263         }
 264
 265         local_irq_restore(flags);
 266 }
 267
 268 static struct dentry *blk_tree_root;
 269 static DEFINE_MUTEX(blk_tree_mutex);
 270
 271 static void blk_trace_free(struct blk_trace *bt)
 272 {
 273         debugfs_remove(bt->msg_file);
 274         debugfs_remove(bt->dropped_file);
 275         relay_close(bt->rchan);
 276         debugfs_remove(bt->dir);
 277         free_percpu(bt->sequence);
 278         free_percpu(bt->msg_data);
 279         kfree(bt);
 280 }
 281
 282 static void blk_trace_cleanup(struct blk_trace *bt)
 283 {
 284         blk_trace_free(bt);
 285         if (atomic_dec_and_test(&blk_probes_ref))
 286                 blk_unregister_tracepoints();
 287 }
 288
 289 int blk_trace_remove(struct request_queue *q)
 290 {
 291         struct blk_trace *bt;
 292
 293         bt = xchg(&q->blk_trace, NULL);
 294         if (!bt)
 295                 return -EINVAL;
 296
 297         if (bt->trace_state != Blktrace_running)
 298                 blk_trace_cleanup(bt);
 299
 300         return 0;
 301 }
 302 EXPORT_SYMBOL_GPL(blk_trace_remove);
 303
 304 static int blk_dropped_open(struct inode *inode, struct file *filp)
 305 {
 306         filp->private_data = inode->i_private;
 307
 308         return 0;
 309 }
 310
 311 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
 312                                 size_t count, loff_t *ppos)
 313 {
 314         struct blk_trace *bt = filp->private_data;
 315         char buf[16];
 316
 317         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
 318
 319         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 320 }
 321
 322 static const struct file_operations blk_dropped_fops = {
 323         .owner =        THIS_MODULE,
 324         .open =         blk_dropped_open,
 325         .read =         blk_dropped_read,
 326 };
 327
 328 static int blk_msg_open(struct inode *inode, struct file *filp)
 329 {
 330         filp->private_data = inode->i_private;
 331
 332         return 0;
 333 }
 334
 335 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 336                                 size_t count, loff_t *ppos)
 337 {
 338         char *msg;
 339         struct blk_trace *bt;
 340
 341         if (count >= BLK_TN_MAX_MSG)
 342                 return -EINVAL;
 343
 344         msg = kmalloc(count + 1, GFP_KERNEL);
 345         if (msg == NULL)
 346                 return -ENOMEM;
 347
 348         if (copy_from_user(msg, buffer, count)) {
 349                 kfree(msg);
 350                 return -EFAULT;
 351         }
 352
 353         msg[count] = '\0';
 354         bt = filp->private_data;
 355         __trace_note_message(bt, "%s", msg);
 356         kfree(msg);
 357
 358         return count;
 359 }
 360
 361 static const struct file_operations blk_msg_fops = {
 362         .owner =        THIS_MODULE,
 363         .open =         blk_msg_open,
 364         .write =        blk_msg_write,
 365 };
 366
 367 /*
 368  * Keep track of how many times we encountered a full subbuffer, to aid
 369  * the user space app in telling how many lost events there were.
 370  */
 371 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
 372                                      void *prev_subbuf, size_t prev_padding)
 373 {
 374         struct blk_trace *bt;
 375
 376         if (!relay_buf_full(buf))
 377                 return 1;
 378
 379         bt = buf->chan->private_data;
 380         atomic_inc(&bt->dropped);
 381         return 0;
 382 }
 383
 384 static int blk_remove_buf_file_callback(struct dentry *dentry)
 385 {
 386         debugfs_remove(dentry);
 387
 388         return 0;
 389 }
 390
 391 static struct dentry *blk_create_buf_file_callback(const char *filename,
 392                                                    struct dentry *parent,
 393                                                    int mode,
 394                                                    struct rchan_buf *buf,
 395                                                    int *is_global)
 396 {
 397         return debugfs_create_file(filename, mode, parent, buf,
 398                                         &relay_file_operations);
 399 }
 400
 401 static struct rchan_callbacks blk_relay_callbacks = {
 402         .subbuf_start           = blk_subbuf_start_callback,
 403         .create_buf_file        = blk_create_buf_file_callback,
 404         .remove_buf_file        = blk_remove_buf_file_callback,
 405 };
 406
 407 static void blk_trace_setup_lba(struct blk_trace *bt,
 408                                 struct block_device *bdev)
 409 {
 410         struct hd_struct *part = NULL;
 411
 412         if (bdev)
 413                 part = bdev->bd_part;
 414
 415         if (part) {
 416                 bt->start_lba = part->start_sect;
 417                 bt->end_lba = part->start_sect + part->nr_sects;
 418         } else {
 419                 bt->start_lba = 0;
 420                 bt->end_lba = -1ULL;
 421         }
 422 }
 423
 424 /*
 425  * Setup everything required to start tracing
 426  */
 427 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 428                        struct block_device *bdev,
 429                        struct blk_user_trace_setup *buts)
 430 {
 431         struct blk_trace *old_bt, *bt = NULL;
 432         struct dentry *dir = NULL;
 433         int ret, i;
 434
 435         if (!buts->buf_size || !buts->buf_nr)
 436                 return -EINVAL;
 437
 438         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 439         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 440
 441         /*
 442          * some device names have larger paths - convert the slashes
 443          * to underscores for this to work as expected
 444          */
 445         for (i = 0; i < strlen(buts->name); i++)
 446                 if (buts->name[i] == '/')
 447                         buts->name[i] = '_';
 448
 449         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 450         if (!bt)
 451                 return -ENOMEM;
 452
 453         ret = -ENOMEM;
 454         bt->sequence = alloc_percpu(unsigned long);
 455         if (!bt->sequence)
 456                 goto err;
 457
 458         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 459         if (!bt->msg_data)
 460                 goto err;
 461
 462         ret = -ENOENT;
 463
 464         mutex_lock(&blk_tree_mutex);
 465         if (!blk_tree_root) {
 466                 blk_tree_root = debugfs_create_dir("block", NULL);
 467                 if (!blk_tree_root) {
 468                         mutex_unlock(&blk_tree_mutex);
 469                         goto err;
 470                 }
 471         }
 472         mutex_unlock(&blk_tree_mutex);
 473
 474         dir = debugfs_create_dir(buts->name, blk_tree_root);
 475
 476         if (!dir)
 477                 goto err;
 478
 479         bt->dir = dir;
 480         bt->dev = dev;
 481         atomic_set(&bt->dropped, 0);
 482
 483         ret = -EIO;
 484         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 485                                                &blk_dropped_fops);
 486         if (!bt->dropped_file)
 487                 goto err;
 488
 489         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 490         if (!bt->msg_file)
 491                 goto err;
 492
 493         bt->rchan = relay_open("trace", dir, buts->buf_size,
 494                                 buts->buf_nr, &blk_relay_callbacks, bt);
 495         if (!bt->rchan)
 496                 goto err;
 497
 498         bt->act_mask = buts->act_mask;
 499         if (!bt->act_mask)
 500                 bt->act_mask = (u16) -1;
 501
 502         blk_trace_setup_lba(bt, bdev);
 503
 504         /* overwrite with user settings */
 505         if (buts->start_lba)
 506                 bt->start_lba = buts->start_lba;
 507         if (buts->end_lba)
 508                 bt->end_lba = buts->end_lba;
 509
 510         bt->pid = buts->pid;
 511         bt->trace_state = Blktrace_setup;
 512
 513         ret = -EBUSY;
 514         old_bt = xchg(&q->blk_trace, bt);
 515         if (old_bt) {
 516                 (void) xchg(&q->blk_trace, old_bt);
 517                 goto err;
 518         }
 519
 520         if (atomic_inc_return(&blk_probes_ref) == 1)
 521                 blk_register_tracepoints();
 522
 523         return 0;
 524 err:
 525         blk_trace_free(bt);
 526         return ret;
 527 }
 528
 529 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 530                     struct block_device *bdev,
 531                     char __user *arg)
 532 {
 533         struct blk_user_trace_setup buts;
 534         int ret;
 535
 536         ret = copy_from_user(&buts, arg, sizeof(buts));
 537         if (ret)
 538                 return -EFAULT;
 539
 540         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 541         if (ret)
 542                 return ret;
 543
 544         if (copy_to_user(arg, &buts, sizeof(buts))) {
 545                 blk_trace_remove(q);
 546                 return -EFAULT;
 547         }
 548         return 0;
 549 }
 550 EXPORT_SYMBOL_GPL(blk_trace_setup);
 551
 552 int blk_trace_startstop(struct request_queue *q, int start)
 553 {
 554         int ret;
 555         struct blk_trace *bt = q->blk_trace;
 556
 557         if (bt == NULL)
 558                 return -EINVAL;
 559
 560         /*
 561          * For starting a trace, we can transition from a setup or stopped
 562          * trace. For stopping a trace, the state must be running
 563          */
 564         ret = -EINVAL;
 565         if (start) {
 566                 if (bt->trace_state == Blktrace_setup ||
 567                     bt->trace_state == Blktrace_stopped) {
 568                         blktrace_seq++;
 569                         smp_mb();
 570                         bt->trace_state = Blktrace_running;
 571
 572                         trace_note_time(bt);
 573                         ret = 0;
 574                 }
 575         } else {
 576                 if (bt->trace_state == Blktrace_running) {
 577                         bt->trace_state = Blktrace_stopped;
 578                         relay_flush(bt->rchan);
 579                         ret = 0;
 580                 }
 581         }
 582
 583         return ret;
 584 }
 585 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 586
 587 /**
 588  * blk_trace_ioctl: - handle the ioctls associated with tracing
 589  * @bdev:       the block device
 590  * @cmd:        the ioctl cmd
 591  * @arg:        the argument data, if any
 592  *
 593  **/
 594 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 595 {
 596         struct request_queue *q;
 597         int ret, start = 0;
 598         char b[BDEVNAME_SIZE];
 599
 600         q = bdev_get_queue(bdev);
 601         if (!q)
 602                 return -ENXIO;
 603
 604         mutex_lock(&bdev->bd_mutex);
 605
 606         switch (cmd) {
 607         case BLKTRACESETUP:
 608                 bdevname(bdev, b);
 609                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 610                 break;
 611         case BLKTRACESTART:
 612                 start = 1;
 613         case BLKTRACESTOP:
 614                 ret = blk_trace_startstop(q, start);
 615                 break;
 616         case BLKTRACETEARDOWN:
 617                 ret = blk_trace_remove(q);
 618                 break;
 619         default:
 620                 ret = -ENOTTY;
 621                 break;
 622         }
 623
 624         mutex_unlock(&bdev->bd_mutex);
 625         return ret;
 626 }
 627
 628 /**
 629  * blk_trace_shutdown: - stop and cleanup trace structures
 630  * @q:    the request queue associated with the device
 631  *
 632  **/
 633 void blk_trace_shutdown(struct request_queue *q)
 634 {
 635         if (q->blk_trace) {
 636                 blk_trace_startstop(q, 0);
 637                 blk_trace_remove(q);
 638         }
 639 }
 640
 641 /*
 642  * blktrace probes
 643  */
 644
 645 /**
 646  * blk_add_trace_rq - Add a trace for a request oriented action
 647  * @q:          queue the io is for
 648  * @rq:         the source request
 649  * @what:       the action
 650  *
 651  * Description:
 652  *     Records an action against a request. Will log the bio offset + size.
 653  *
 654  **/
 655 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 656                                     u32 what)
 657 {
 658         struct blk_trace *bt = q->blk_trace;
 659         int rw = rq->cmd_flags & 0x03;
 660
 661         if (likely(!bt))
 662                 return;
 663
 664         if (blk_discard_rq(rq))
 665                 rw |= (1 << BIO_RW_DISCARD);
 666
 667         if (blk_pc_request(rq)) {
 668                 what |= BLK_TC_ACT(BLK_TC_PC);
 669                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), rw,
 670                                 what, rq->errors, rq->cmd_len, rq->cmd);
 671         } else  {
 672                 what |= BLK_TC_ACT(BLK_TC_FS);
 673                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), rw,
 674                                 what, rq->errors, 0, NULL);
 675         }
 676 }
 677
 678 static void blk_add_trace_rq_abort(void *ignore,
 679                                    struct request_queue *q, struct request *rq)
 680 {
 681         blk_add_trace_rq(q, rq, BLK_TA_ABORT);
 682 }
 683
 684 static void blk_add_trace_rq_insert(void *ignore,
 685                                     struct request_queue *q, struct request *rq)
 686 {
 687         blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 688 }
 689
 690 static void blk_add_trace_rq_issue(void *ignore,
 691                                    struct request_queue *q, struct request *rq)
 692 {
 693         blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
 694 }
 695
 696 static void blk_add_trace_rq_requeue(void *ignore,
 697                                      struct request_queue *q,
 698                                      struct request *rq)
 699 {
 700         blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
 701 }
 702
 703 static void blk_add_trace_rq_complete(void *ignore,
 704                                       struct request_queue *q,
 705                                       struct request *rq)
 706 {
 707         blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
 708 }
 709
 710 /**
 711  * blk_add_trace_bio - Add a trace for a bio oriented action
 712  * @q:          queue the io is for
 713  * @bio:        the source bio
 714  * @what:       the action
 715  *
 716  * Description:
 717  *     Records an action against a bio. Will log the bio offset + size.
 718  *
 719  **/
 720 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 721                                      u32 what)
 722 {
 723         struct blk_trace *bt = q->blk_trace;
 724
 725         if (likely(!bt))
 726                 return;
 727
 728         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
 729                         !bio_flagged(bio, BIO_UPTODATE), 0, NULL);
 730 }
 731
 732 static void blk_add_trace_bio_bounce(void *ignore,
 733                                      struct request_queue *q, struct bio *bio)
 734 {
 735         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE);
 736 }
 737
 738 static void blk_add_trace_bio_complete(void *ignore,
 739                                        struct request_queue *q, struct bio *bio)
 740 {
 741         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE);
 742 }
 743
 744 static void blk_add_trace_bio_backmerge(void *ignore,
 745                                         struct request_queue *q,
 746                                         struct bio *bio)
 747 {
 748         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
 749 }
 750
 751 static void blk_add_trace_bio_frontmerge(void *ignore,
 752                                          struct request_queue *q,
 753                                          struct bio *bio)
 754 {
 755         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
 756 }
 757
 758 static void blk_add_trace_bio_queue(void *ignore,
 759                                     struct request_queue *q, struct bio *bio)
 760 {
 761         blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
 762 }
 763
 764 static void blk_add_trace_getrq(void *ignore,
 765                                 struct request_queue *q,
 766                                 struct bio *bio, int rw)
 767 {
 768         if (bio)
 769                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ);
 770         else {
 771                 struct blk_trace *bt = q->blk_trace;
 772
 773                 if (bt)
 774                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
 775         }
 776 }
 777
 778
 779 static void blk_add_trace_sleeprq(void *ignore,
 780                                   struct request_queue *q,
 781                                   struct bio *bio, int rw)
 782 {
 783         if (bio)
 784                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ);
 785         else {
 786                 struct blk_trace *bt = q->blk_trace;
 787
 788                 if (bt)
 789                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
 790                                         0, 0, NULL);
 791         }
 792 }
 793
 794 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 795 {
 796         struct blk_trace *bt = q->blk_trace;
 797
 798         if (bt)
 799                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
 800 }
 801
 802 static void blk_add_trace_unplug_io(void *ignore, 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_IO, 0,
 811                                 sizeof(rpdu), &rpdu);
 812         }
 813 }
 814
 815 static void blk_add_trace_unplug_timer(void *ignore, struct request_queue *q)
 816 {
 817         struct blk_trace *bt = q->blk_trace;
 818
 819         if (bt) {
 820                 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
 821                 __be64 rpdu = cpu_to_be64(pdu);
 822
 823                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_TIMER, 0,
 824                                 sizeof(rpdu), &rpdu);
 825         }
 826 }
 827
 828 static void blk_add_trace_split(void *ignore,
 829                                 struct request_queue *q, struct bio *bio,
 830                                 unsigned int pdu)
 831 {
 832         struct blk_trace *bt = q->blk_trace;
 833
 834         if (bt) {
 835                 __be64 rpdu = cpu_to_be64(pdu);
 836
 837                 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 838                                 BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
 839                                 sizeof(rpdu), &rpdu);
 840         }
 841 }
 842
 843 /**
 844  * blk_add_trace_remap - Add a trace for a remap operation
 845  * @q:          queue the io is for
 846  * @bio:        the source bio
 847  * @dev:        target device
 848  * @from:       source sector
 849  *
 850  * Description:
 851  *     Device mapper or raid target sometimes need to split a bio because
 852  *     it spans a stripe (or similar). Add a trace for that action.
 853  *
 854  **/
 855 static void blk_add_trace_remap(void *ignore,
 856                                 struct request_queue *q, struct bio *bio,
 857                                 dev_t dev, sector_t from)
 858 {
 859         struct blk_trace *bt = q->blk_trace;
 860         struct blk_io_trace_remap r;
 861
 862         if (likely(!bt))
 863                 return;
 864
 865         r.device_from = cpu_to_be32(dev);
 866         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
 867         r.sector_from = cpu_to_be64(from);
 868
 869         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 870                         BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE),
 871                         sizeof(r), &r);
 872 }
 873
 874 /**
 875  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
 876  * @q:          queue the io is for
 877  * @rq:         the source request
 878  * @dev:        target device
 879  * @from:       source sector
 880  *
 881  * Description:
 882  *     Device mapper remaps request to other devices.
 883  *     Add a trace for that action.
 884  *
 885  **/
 886 static void blk_add_trace_rq_remap(void *ignore,
 887                                    struct request_queue *q,
 888                                    struct request *rq, dev_t dev,
 889                                    sector_t from)
 890 {
 891         struct blk_trace *bt = q->blk_trace;
 892         struct blk_io_trace_remap r;
 893
 894         if (likely(!bt))
 895                 return;
 896
 897         r.device_from = cpu_to_be32(dev);
 898         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
 899         r.sector_from = cpu_to_be64(from);
 900
 901         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 902                         rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
 903                         sizeof(r), &r);
 904 }
 905
 906 /**
 907  * blk_add_driver_data - Add binary message with driver-specific data
 908  * @q:          queue the io is for
 909  * @rq:         io request
 910  * @data:       driver-specific data
 911  * @len:        length of driver-specific data
 912  *
 913  * Description:
 914  *     Some drivers might want to write driver-specific data per request.
 915  *
 916  **/
 917 void blk_add_driver_data(struct request_queue *q,
 918                          struct request *rq,
 919                          void *data, size_t len)
 920 {
 921         struct blk_trace *bt = q->blk_trace;
 922
 923         if (likely(!bt))
 924                 return;
 925
 926         if (blk_pc_request(rq))
 927                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
 928                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 929         else
 930                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
 931                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 932 }
 933 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 934
 935 static void blk_register_tracepoints(void)
 936 {
 937         int ret;
 938
 939         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
 940         WARN_ON(ret);
 941         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
 942         WARN_ON(ret);
 943         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
 944         WARN_ON(ret);
 945         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
 946         WARN_ON(ret);
 947         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
 948         WARN_ON(ret);
 949         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
 950         WARN_ON(ret);
 951         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
 952         WARN_ON(ret);
 953         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
 954         WARN_ON(ret);
 955         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
 956         WARN_ON(ret);
 957         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
 958         WARN_ON(ret);
 959         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
 960         WARN_ON(ret);
 961         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
 962         WARN_ON(ret);
 963         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
 964         WARN_ON(ret);
 965         ret = register_trace_block_unplug_timer(blk_add_trace_unplug_timer, NULL);
 966         WARN_ON(ret);
 967         ret = register_trace_block_unplug_io(blk_add_trace_unplug_io, NULL);
 968         WARN_ON(ret);
 969         ret = register_trace_block_split(blk_add_trace_split, NULL);
 970         WARN_ON(ret);
 971         ret = register_trace_block_remap(blk_add_trace_remap, NULL);
 972         WARN_ON(ret);
 973         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
 974         WARN_ON(ret);
 975 }
 976
 977 static void blk_unregister_tracepoints(void)
 978 {
 979         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
 980         unregister_trace_block_remap(blk_add_trace_remap, NULL);
 981         unregister_trace_block_split(blk_add_trace_split, NULL);
 982         unregister_trace_block_unplug_io(blk_add_trace_unplug_io, NULL);
 983         unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer, NULL);
 984         unregister_trace_block_plug(blk_add_trace_plug, NULL);
 985         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
 986         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
 987         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
 988         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
 989         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
 990         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
 991         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
 992         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
 993         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
 994         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
 995         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
 996         unregister_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
 997
 998         tracepoint_synchronize_unregister();
 999 }
1000
1001 /*
1002  * struct blk_io_tracer formatting routines
1003  */
1004
1005 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1006 {
1007         int i = 0;
1008         int tc = t->action >> BLK_TC_SHIFT;
1009
1010         if (t->action == BLK_TN_MESSAGE) {
1011                 rwbs[i++] = 'N';
1012                 goto out;
1013         }
1014
1015         if (tc & BLK_TC_DISCARD)
1016                 rwbs[i++] = 'D';
1017         else if (tc & BLK_TC_WRITE)
1018                 rwbs[i++] = 'W';
1019         else if (t->bytes)
1020                 rwbs[i++] = 'R';
1021         else
1022                 rwbs[i++] = 'N';
1023
1024         if (tc & BLK_TC_AHEAD)
1025                 rwbs[i++] = 'A';
1026         if (tc & BLK_TC_BARRIER)
1027                 rwbs[i++] = 'B';
1028         if (tc & BLK_TC_SYNC)
1029                 rwbs[i++] = 'S';
1030         if (tc & BLK_TC_META)
1031                 rwbs[i++] = 'M';
1032 out:
1033         rwbs[i] = '\0';
1034 }
1035
1036 static inline
1037 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1038 {
1039         return (const struct blk_io_trace *)ent;
1040 }
1041
1042 static inline const void *pdu_start(const struct trace_entry *ent)
1043 {
1044         return te_blk_io_trace(ent) + 1;
1045 }
1046
1047 static inline u32 t_action(const struct trace_entry *ent)
1048 {
1049         return te_blk_io_trace(ent)->action;
1050 }
1051
1052 static inline u32 t_bytes(const struct trace_entry *ent)
1053 {
1054         return te_blk_io_trace(ent)->bytes;
1055 }
1056
1057 static inline u32 t_sec(const struct trace_entry *ent)
1058 {
1059         return te_blk_io_trace(ent)->bytes >> 9;
1060 }
1061
1062 static inline unsigned long long t_sector(const struct trace_entry *ent)
1063 {
1064         return te_blk_io_trace(ent)->sector;
1065 }
1066
1067 static inline __u16 t_error(const struct trace_entry *ent)
1068 {
1069         return te_blk_io_trace(ent)->error;
1070 }
1071
1072 static __u64 get_pdu_int(const struct trace_entry *ent)
1073 {
1074         const __u64 *val = pdu_start(ent);
1075         return be64_to_cpu(*val);
1076 }
1077
1078 static void get_pdu_remap(const struct trace_entry *ent,
1079                           struct blk_io_trace_remap *r)
1080 {
1081         const struct blk_io_trace_remap *__r = pdu_start(ent);
1082         __u64 sector_from = __r->sector_from;
1083
1084         r->device_from = be32_to_cpu(__r->device_from);
1085         r->device_to   = be32_to_cpu(__r->device_to);
1086         r->sector_from = be64_to_cpu(sector_from);
1087 }
1088
1089 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1090
1091 static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1092 {
1093         char rwbs[6];
1094         unsigned long long ts  = iter->ts;
1095         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1096         unsigned secs          = (unsigned long)ts;
1097         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1098
1099         fill_rwbs(rwbs, t);
1100
1101         return trace_seq_printf(&iter->seq,
1102                                 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1103                                 MAJOR(t->device), MINOR(t->device), iter->cpu,
1104                                 secs, nsec_rem, iter->ent->pid, act, rwbs);
1105 }
1106
1107 static int blk_log_action(struct trace_iterator *iter, const char *act)
1108 {
1109         char rwbs[6];
1110         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1111
1112         fill_rwbs(rwbs, t);
1113         return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1114                                 MAJOR(t->device), MINOR(t->device), act, rwbs);
1115 }
1116
1117 static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1118 {
1119         const unsigned char *pdu_buf;
1120         int pdu_len;
1121         int i, end, ret;
1122
1123         pdu_buf = pdu_start(ent);
1124         pdu_len = te_blk_io_trace(ent)->pdu_len;
1125
1126         if (!pdu_len)
1127                 return 1;
1128
1129         /* find the last zero that needs to be printed */
1130         for (end = pdu_len - 1; end >= 0; end--)
1131                 if (pdu_buf[end])
1132                         break;
1133         end++;
1134
1135         if (!trace_seq_putc(s, '('))
1136                 return 0;
1137
1138         for (i = 0; i < pdu_len; i++) {
1139
1140                 ret = trace_seq_printf(s, "%s%02x",
1141                                        i == 0 ? "" : " ", pdu_buf[i]);
1142                 if (!ret)
1143                         return ret;
1144
1145                 /*
1146                  * stop when the rest is just zeroes and indicate so
1147                  * with a ".." appended
1148                  */
1149                 if (i == end && end != pdu_len - 1)
1150                         return trace_seq_puts(s, " ..) ");
1151         }
1152
1153         return trace_seq_puts(s, ") ");
1154 }
1155
1156 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1157 {
1158         char cmd[TASK_COMM_LEN];
1159
1160         trace_find_cmdline(ent->pid, cmd);
1161
1162         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1163                 int ret;
1164
1165                 ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1166                 if (!ret)
1167                         return 0;
1168                 ret = blk_log_dump_pdu(s, ent);
1169                 if (!ret)
1170                         return 0;
1171                 return trace_seq_printf(s, "[%s]\n", cmd);
1172         } else {
1173                 if (t_sec(ent))
1174                         return trace_seq_printf(s, "%llu + %u [%s]\n",
1175                                                 t_sector(ent), t_sec(ent), cmd);
1176                 return trace_seq_printf(s, "[%s]\n", cmd);
1177         }
1178 }
1179
1180 static int blk_log_with_error(struct trace_seq *s,
1181                               const struct trace_entry *ent)
1182 {
1183         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1184                 int ret;
1185
1186                 ret = blk_log_dump_pdu(s, ent);
1187                 if (ret)
1188                         return trace_seq_printf(s, "[%d]\n", t_error(ent));
1189                 return 0;
1190         } else {
1191                 if (t_sec(ent))
1192                         return trace_seq_printf(s, "%llu + %u [%d]\n",
1193                                                 t_sector(ent),
1194                                                 t_sec(ent), t_error(ent));
1195                 return trace_seq_printf(s, "%llu [%d]\n",
1196                                         t_sector(ent), t_error(ent));
1197         }
1198 }
1199
1200 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1201 {
1202         struct blk_io_trace_remap r = { .device_from = 0, };
1203
1204         get_pdu_remap(ent, &r);
1205         return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1206                                 t_sector(ent), t_sec(ent),
1207                                 MAJOR(r.device_from), MINOR(r.device_from),
1208                                 (unsigned long long)r.sector_from);
1209 }
1210
1211 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1212 {
1213         char cmd[TASK_COMM_LEN];
1214
1215         trace_find_cmdline(ent->pid, cmd);
1216
1217         return trace_seq_printf(s, "[%s]\n", cmd);
1218 }
1219
1220 static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1221 {
1222         char cmd[TASK_COMM_LEN];
1223
1224         trace_find_cmdline(ent->pid, cmd);
1225
1226         return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1227 }
1228
1229 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1230 {
1231         char cmd[TASK_COMM_LEN];
1232
1233         trace_find_cmdline(ent->pid, cmd);
1234
1235         return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1236                                 get_pdu_int(ent), cmd);
1237 }
1238
1239 static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1240 {
1241         int ret;
1242         const struct blk_io_trace *t = te_blk_io_trace(ent);
1243
1244         ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1245         if (ret)
1246                 return trace_seq_putc(s, '\n');
1247         return ret;
1248 }
1249
1250 /*
1251  * struct tracer operations
1252  */
1253
1254 static void blk_tracer_print_header(struct seq_file *m)
1255 {
1256         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1257                 return;
1258         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1259                     "#  |     |     |           |   |   |\n");
1260 }
1261
1262 static void blk_tracer_start(struct trace_array *tr)
1263 {
1264         blk_tracer_enabled = true;
1265 }
1266
1267 static int blk_tracer_init(struct trace_array *tr)
1268 {
1269         blk_tr = tr;
1270         blk_tracer_start(tr);
1271         return 0;
1272 }
1273
1274 static void blk_tracer_stop(struct trace_array *tr)
1275 {
1276         blk_tracer_enabled = false;
1277 }
1278
1279 static void blk_tracer_reset(struct trace_array *tr)
1280 {
1281         blk_tracer_stop(tr);
1282 }
1283
1284 static const struct {
1285         const char *act[2];
1286         int        (*print)(struct trace_seq *s, const struct trace_entry *ent);
1287 } what2act[] = {
1288         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1289         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1290         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1291         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1292         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1293         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1294         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1295         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1296         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1297         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1298         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1299         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1300         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1301         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1302         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1303 };
1304
1305 static enum print_line_t print_one_line(struct trace_iterator *iter,
1306                                         bool classic)
1307 {
1308         struct trace_seq *s = &iter->seq;
1309         const struct blk_io_trace *t;
1310         u16 what;
1311         int ret;
1312         bool long_act;
1313         blk_log_action_t *log_action;
1314
1315         t          = te_blk_io_trace(iter->ent);
1316         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1317         long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1318         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1319
1320         if (t->action == BLK_TN_MESSAGE) {
1321                 ret = log_action(iter, long_act ? "message" : "m");
1322                 if (ret)
1323                         ret = blk_log_msg(s, iter->ent);
1324                 goto out;
1325         }
1326
1327         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1328                 ret = trace_seq_printf(s, "Unknown action %x\n", what);
1329         else {
1330                 ret = log_action(iter, what2act[what].act[long_act]);
1331                 if (ret)
1332                         ret = what2act[what].print(s, iter->ent);
1333         }
1334 out:
1335         return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1336 }
1337
1338 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1339                                                int flags, struct trace_event *event)
1340 {
1341         return print_one_line(iter, false);
1342 }
1343
1344 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1345 {
1346         struct trace_seq *s = &iter->seq;
1347         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1348         const int offset = offsetof(struct blk_io_trace, sector);
1349         struct blk_io_trace old = {
1350                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1351                 .time     = iter->ts,
1352         };
1353
1354         if (!trace_seq_putmem(s, &old, offset))
1355                 return 0;
1356         return trace_seq_putmem(s, &t->sector,
1357                                 sizeof(old) - offset + t->pdu_len);
1358 }
1359
1360 static enum print_line_t
1361 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1362                              struct trace_event *event)
1363 {
1364         return blk_trace_synthesize_old_trace(iter) ?
1365                         TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1366 }
1367
1368 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1369 {
1370         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1371                 return TRACE_TYPE_UNHANDLED;
1372
1373         return print_one_line(iter, true);
1374 }
1375
1376 static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
1377 {
1378         /* don't output context-info for blk_classic output */
1379         if (bit == TRACE_BLK_OPT_CLASSIC) {
1380                 if (set)
1381                         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1382                 else
1383                         trace_flags |= TRACE_ITER_CONTEXT_INFO;
1384         }
1385         return 0;
1386 }
1387
1388 static struct tracer blk_tracer __read_mostly = {
1389         .name           = "blk",
1390         .init           = blk_tracer_init,
1391         .reset          = blk_tracer_reset,
1392         .start          = blk_tracer_start,
1393         .stop           = blk_tracer_stop,
1394         .print_header   = blk_tracer_print_header,
1395         .print_line     = blk_tracer_print_line,
1396         .flags          = &blk_tracer_flags,
1397         .set_flag       = blk_tracer_set_flag,
1398 };
1399
1400 static struct trace_event_functions trace_blk_event_funcs = {
1401         .trace          = blk_trace_event_print,
1402         .binary         = blk_trace_event_print_binary,
1403 };
1404
1405 static struct trace_event trace_blk_event = {
1406         .type           = TRACE_BLK,
1407         .funcs          = &trace_blk_event_funcs,
1408 };
1409
1410 static int __init init_blk_tracer(void)
1411 {
1412         if (!register_ftrace_event(&trace_blk_event)) {
1413                 pr_warning("Warning: could not register block events\n");
1414                 return 1;
1415         }
1416
1417         if (register_tracer(&blk_tracer) != 0) {
1418                 pr_warning("Warning: could not register the block tracer\n");
1419                 unregister_ftrace_event(&trace_blk_event);
1420                 return 1;
1421         }
1422
1423         return 0;
1424 }
1425
1426 device_initcall(init_blk_tracer);
1427
1428 static int blk_trace_remove_queue(struct request_queue *q)
1429 {
1430         struct blk_trace *bt;
1431
1432         bt = xchg(&q->blk_trace, NULL);
1433         if (bt == NULL)
1434                 return -EINVAL;
1435
1436         if (atomic_dec_and_test(&blk_probes_ref))
1437                 blk_unregister_tracepoints();
1438
1439         blk_trace_free(bt);
1440         return 0;
1441 }
1442
1443 /*
1444  * Setup everything required to start tracing
1445  */
1446 static int blk_trace_setup_queue(struct request_queue *q,
1447                                  struct block_device *bdev)
1448 {
1449         struct blk_trace *old_bt, *bt = NULL;
1450         int ret = -ENOMEM;
1451
1452         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1453         if (!bt)
1454                 return -ENOMEM;
1455
1456         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1457         if (!bt->msg_data)
1458                 goto free_bt;
1459
1460         bt->dev = bdev->bd_dev;
1461         bt->act_mask = (u16)-1;
1462
1463         blk_trace_setup_lba(bt, bdev);
1464
1465         old_bt = xchg(&q->blk_trace, bt);
1466         if (old_bt != NULL) {
1467                 (void)xchg(&q->blk_trace, old_bt);
1468                 ret = -EBUSY;
1469                 goto free_bt;
1470         }
1471
1472         if (atomic_inc_return(&blk_probes_ref) == 1)
1473                 blk_register_tracepoints();
1474         return 0;
1475
1476 free_bt:
1477         blk_trace_free(bt);
1478         return ret;
1479 }
1480
1481 /*
1482  * sysfs interface to enable and configure tracing
1483  */
1484
1485 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1486                                          struct device_attribute *attr,
1487                                          char *buf);
1488 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1489                                           struct device_attribute *attr,
1490                                           const char *buf, size_t count);
1491 #define BLK_TRACE_DEVICE_ATTR(_name) \
1492         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1493                     sysfs_blk_trace_attr_show, \
1494                     sysfs_blk_trace_attr_store)
1495
1496 static BLK_TRACE_DEVICE_ATTR(enable);
1497 static BLK_TRACE_DEVICE_ATTR(act_mask);
1498 static BLK_TRACE_DEVICE_ATTR(pid);
1499 static BLK_TRACE_DEVICE_ATTR(start_lba);
1500 static BLK_TRACE_DEVICE_ATTR(end_lba);
1501
1502 static struct attribute *blk_trace_attrs[] = {
1503         &dev_attr_enable.attr,
1504         &dev_attr_act_mask.attr,
1505         &dev_attr_pid.attr,
1506         &dev_attr_start_lba.attr,
1507         &dev_attr_end_lba.attr,
1508         NULL
1509 };
1510
1511 struct attribute_group blk_trace_attr_group = {
1512         .name  = "trace",
1513         .attrs = blk_trace_attrs,
1514 };
1515
1516 static const struct {
1517         int mask;
1518         const char *str;
1519 } mask_maps[] = {
1520         { BLK_TC_READ,          "read"          },
1521         { BLK_TC_WRITE,         "write"         },
1522         { BLK_TC_BARRIER,       "barrier"       },
1523         { BLK_TC_SYNC,          "sync"          },
1524         { BLK_TC_QUEUE,         "queue"         },
1525         { BLK_TC_REQUEUE,       "requeue"       },
1526         { BLK_TC_ISSUE,         "issue"         },
1527         { BLK_TC_COMPLETE,      "complete"      },
1528         { BLK_TC_FS,            "fs"            },
1529         { BLK_TC_PC,            "pc"            },
1530         { BLK_TC_AHEAD,         "ahead"         },
1531         { BLK_TC_META,          "meta"          },
1532         { BLK_TC_DISCARD,       "discard"       },
1533         { BLK_TC_DRV_DATA,      "drv_data"      },
1534 };
1535
1536 static int blk_trace_str2mask(const char *str)
1537 {
1538         int i;
1539         int mask = 0;
1540         char *buf, *s, *token;
1541
1542         buf = kstrdup(str, GFP_KERNEL);
1543         if (buf == NULL)
1544                 return -ENOMEM;
1545         s = strstrip(buf);
1546
1547         while (1) {
1548                 token = strsep(&s, ",");
1549                 if (token == NULL)
1550                         break;
1551
1552                 if (*token == '\0')
1553                         continue;
1554
1555                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1556                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1557                                 mask |= mask_maps[i].mask;
1558                                 break;
1559                         }
1560                 }
1561                 if (i == ARRAY_SIZE(mask_maps)) {
1562                         mask = -EINVAL;
1563                         break;
1564                 }
1565         }
1566         kfree(buf);
1567
1568         return mask;
1569 }
1570
1571 static ssize_t blk_trace_mask2str(char *buf, int mask)
1572 {
1573         int i;
1574         char *p = buf;
1575
1576         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1577                 if (mask & mask_maps[i].mask) {
1578                         p += sprintf(p, "%s%s",
1579                                     (p == buf) ? "" : ",", mask_maps[i].str);
1580                 }
1581         }
1582         *p++ = '\n';
1583
1584         return p - buf;
1585 }
1586
1587 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1588 {
1589         if (bdev->bd_disk == NULL)
1590                 return NULL;
1591
1592         return bdev_get_queue(bdev);
1593 }
1594
1595 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1596                                          struct device_attribute *attr,
1597                                          char *buf)
1598 {
1599         struct hd_struct *p = dev_to_part(dev);
1600         struct request_queue *q;
1601         struct block_device *bdev;
1602         ssize_t ret = -ENXIO;
1603
1604         lock_kernel();
1605         bdev = bdget(part_devt(p));
1606         if (bdev == NULL)
1607                 goto out_unlock_kernel;
1608
1609         q = blk_trace_get_queue(bdev);
1610         if (q == NULL)
1611                 goto out_bdput;
1612
1613         mutex_lock(&bdev->bd_mutex);
1614
1615         if (attr == &dev_attr_enable) {
1616                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1617                 goto out_unlock_bdev;
1618         }
1619
1620         if (q->blk_trace == NULL)
1621                 ret = sprintf(buf, "disabled\n");
1622         else if (attr == &dev_attr_act_mask)
1623                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1624         else if (attr == &dev_attr_pid)
1625                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1626         else if (attr == &dev_attr_start_lba)
1627                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1628         else if (attr == &dev_attr_end_lba)
1629                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1630
1631 out_unlock_bdev:
1632         mutex_unlock(&bdev->bd_mutex);
1633 out_bdput:
1634         bdput(bdev);
1635 out_unlock_kernel:
1636         unlock_kernel();
1637         return ret;
1638 }
1639
1640 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1641                                           struct device_attribute *attr,
1642                                           const char *buf, size_t count)
1643 {
1644         struct block_device *bdev;
1645         struct request_queue *q;
1646         struct hd_struct *p;
1647         u64 value;
1648         ssize_t ret = -EINVAL;
1649
1650         if (count == 0)
1651                 goto out;
1652
1653         if (attr == &dev_attr_act_mask) {
1654                 if (sscanf(buf, "%llx", &value) != 1) {
1655                         /* Assume it is a list of trace category names */
1656                         ret = blk_trace_str2mask(buf);
1657                         if (ret < 0)
1658                                 goto out;
1659                         value = ret;
1660                 }
1661         } else if (sscanf(buf, "%llu", &value) != 1)
1662                 goto out;
1663
1664         ret = -ENXIO;
1665
1666         lock_kernel();
1667         p = dev_to_part(dev);
1668         bdev = bdget(part_devt(p));
1669         if (bdev == NULL)
1670                 goto out_unlock_kernel;
1671
1672         q = blk_trace_get_queue(bdev);
1673         if (q == NULL)
1674                 goto out_bdput;
1675
1676         mutex_lock(&bdev->bd_mutex);
1677
1678         if (attr == &dev_attr_enable) {
1679                 if (value)
1680                         ret = blk_trace_setup_queue(q, bdev);
1681                 else
1682                         ret = blk_trace_remove_queue(q);
1683                 goto out_unlock_bdev;
1684         }
1685
1686         ret = 0;
1687         if (q->blk_trace == NULL)
1688                 ret = blk_trace_setup_queue(q, bdev);
1689
1690         if (ret == 0) {
1691                 if (attr == &dev_attr_act_mask)
1692                         q->blk_trace->act_mask = value;
1693                 else if (attr == &dev_attr_pid)
1694                         q->blk_trace->pid = value;
1695                 else if (attr == &dev_attr_start_lba)
1696                         q->blk_trace->start_lba = value;
1697                 else if (attr == &dev_attr_end_lba)
1698                         q->blk_trace->end_lba = value;
1699         }
1700
1701 out_unlock_bdev:
1702         mutex_unlock(&bdev->bd_mutex);
1703 out_bdput:
1704         bdput(bdev);
1705 out_unlock_kernel:
1706         unlock_kernel();
1707 out:
1708         return ret ? ret : count;
1709 }
1710
1711 int blk_trace_init_sysfs(struct device *dev)
1712 {
1713         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1714 }
1715
1716 void blk_trace_remove_sysfs(struct device *dev)
1717 {
1718         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1719 }
1720
1721 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1722
1723 #ifdef CONFIG_EVENT_TRACING
1724
1725 void blk_dump_cmd(char *buf, struct request *rq)
1726 {
1727         int i, end;
1728         int len = rq->cmd_len;
1729         unsigned char *cmd = rq->cmd;
1730
1731         if (!blk_pc_request(rq)) {
1732                 buf[0] = '\0';
1733                 return;
1734         }
1735
1736         for (end = len - 1; end >= 0; end--)
1737                 if (cmd[end])
1738                         break;
1739         end++;
1740
1741         for (i = 0; i < len; i++) {
1742                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1743                 if (i == end && end != len - 1) {
1744                         sprintf(buf, " ..");
1745                         break;
1746                 }
1747         }
1748 }
1749
1750 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1751 {
1752         int i = 0;
1753
1754         if (rw & WRITE)
1755                 rwbs[i++] = 'W';
1756         else if (rw & 1 << BIO_RW_DISCARD)
1757                 rwbs[i++] = 'D';
1758         else if (bytes)
1759                 rwbs[i++] = 'R';
1760         else
1761                 rwbs[i++] = 'N';
1762
1763         if (rw & 1 << BIO_RW_AHEAD)
1764                 rwbs[i++] = 'A';
1765         if (rw & 1 << BIO_RW_BARRIER)
1766                 rwbs[i++] = 'B';
1767         if (rw & 1 << BIO_RW_SYNCIO)
1768                 rwbs[i++] = 'S';
1769         if (rw & 1 << BIO_RW_META)
1770                 rwbs[i++] = 'M';
1771
1772         rwbs[i] = '\0';
1773 }
1774
1775 void blk_fill_rwbs_rq(char *rwbs, struct request *rq)
1776 {
1777         int rw = rq->cmd_flags & 0x03;
1778         int bytes;
1779
1780         if (blk_discard_rq(rq))
1781                 rw |= (1 << BIO_RW_DISCARD);
1782
1783         bytes = blk_rq_bytes(rq);
1784
1785         blk_fill_rwbs(rwbs, rw, bytes);
1786 }
1787
1788 #endif /* CONFIG_EVENT_TRACING */
1789