SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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  * @ignore:     trace callback data parameter (not used)
 846  * @q:          queue the io is for
 847  * @bio:        the source bio
 848  * @dev:        target device
 849  * @from:       source sector
 850  *
 851  * Description:
 852  *     Device mapper or raid target sometimes need to split a bio because
 853  *     it spans a stripe (or similar). Add a trace for that action.
 854  *
 855  **/
 856 static void blk_add_trace_remap(void *ignore,
 857                                 struct request_queue *q, struct bio *bio,
 858                                 dev_t dev, sector_t from)
 859 {
 860         struct blk_trace *bt = q->blk_trace;
 861         struct blk_io_trace_remap r;
 862
 863         if (likely(!bt))
 864                 return;
 865
 866         r.device_from = cpu_to_be32(dev);
 867         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
 868         r.sector_from = cpu_to_be64(from);
 869
 870         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 871                         BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE),
 872                         sizeof(r), &r);
 873 }
 874
 875 /**
 876  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
 877  * @ignore:     trace callback data parameter (not used)
 878  * @q:          queue the io is for
 879  * @rq:         the source request
 880  * @dev:        target device
 881  * @from:       source sector
 882  *
 883  * Description:
 884  *     Device mapper remaps request to other devices.
 885  *     Add a trace for that action.
 886  *
 887  **/
 888 static void blk_add_trace_rq_remap(void *ignore,
 889                                    struct request_queue *q,
 890                                    struct request *rq, dev_t dev,
 891                                    sector_t from)
 892 {
 893         struct blk_trace *bt = q->blk_trace;
 894         struct blk_io_trace_remap r;
 895
 896         if (likely(!bt))
 897                 return;
 898
 899         r.device_from = cpu_to_be32(dev);
 900         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
 901         r.sector_from = cpu_to_be64(from);
 902
 903         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 904                         rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
 905                         sizeof(r), &r);
 906 }
 907
 908 /**
 909  * blk_add_driver_data - Add binary message with driver-specific data
 910  * @q:          queue the io is for
 911  * @rq:         io request
 912  * @data:       driver-specific data
 913  * @len:        length of driver-specific data
 914  *
 915  * Description:
 916  *     Some drivers might want to write driver-specific data per request.
 917  *
 918  **/
 919 void blk_add_driver_data(struct request_queue *q,
 920                          struct request *rq,
 921                          void *data, size_t len)
 922 {
 923         struct blk_trace *bt = q->blk_trace;
 924
 925         if (likely(!bt))
 926                 return;
 927
 928         if (blk_pc_request(rq))
 929                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
 930                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 931         else
 932                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
 933                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 934 }
 935 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 936
 937 static void blk_register_tracepoints(void)
 938 {
 939         int ret;
 940
 941         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
 942         WARN_ON(ret);
 943         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
 944         WARN_ON(ret);
 945         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
 946         WARN_ON(ret);
 947         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
 948         WARN_ON(ret);
 949         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
 950         WARN_ON(ret);
 951         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
 952         WARN_ON(ret);
 953         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
 954         WARN_ON(ret);
 955         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
 956         WARN_ON(ret);
 957         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
 958         WARN_ON(ret);
 959         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
 960         WARN_ON(ret);
 961         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
 962         WARN_ON(ret);
 963         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
 964         WARN_ON(ret);
 965         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
 966         WARN_ON(ret);
 967         ret = register_trace_block_unplug_timer(blk_add_trace_unplug_timer, NULL);
 968         WARN_ON(ret);
 969         ret = register_trace_block_unplug_io(blk_add_trace_unplug_io, NULL);
 970         WARN_ON(ret);
 971         ret = register_trace_block_split(blk_add_trace_split, NULL);
 972         WARN_ON(ret);
 973         ret = register_trace_block_remap(blk_add_trace_remap, NULL);
 974         WARN_ON(ret);
 975         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
 976         WARN_ON(ret);
 977 }
 978
 979 static void blk_unregister_tracepoints(void)
 980 {
 981         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
 982         unregister_trace_block_remap(blk_add_trace_remap, NULL);
 983         unregister_trace_block_split(blk_add_trace_split, NULL);
 984         unregister_trace_block_unplug_io(blk_add_trace_unplug_io, NULL);
 985         unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer, NULL);
 986         unregister_trace_block_plug(blk_add_trace_plug, NULL);
 987         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
 988         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
 989         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
 990         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
 991         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
 992         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
 993         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
 994         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
 995         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
 996         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
 997         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
 998         unregister_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
 999
1000         tracepoint_synchronize_unregister();
1001 }
1002
1003 /*
1004  * struct blk_io_tracer formatting routines
1005  */
1006
1007 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1008 {
1009         int i = 0;
1010         int tc = t->action >> BLK_TC_SHIFT;
1011
1012         if (t->action == BLK_TN_MESSAGE) {
1013                 rwbs[i++] = 'N';
1014                 goto out;
1015         }
1016
1017         if (tc & BLK_TC_DISCARD)
1018                 rwbs[i++] = 'D';
1019         else if (tc & BLK_TC_WRITE)
1020                 rwbs[i++] = 'W';
1021         else if (t->bytes)
1022                 rwbs[i++] = 'R';
1023         else
1024                 rwbs[i++] = 'N';
1025
1026         if (tc & BLK_TC_AHEAD)
1027                 rwbs[i++] = 'A';
1028         if (tc & BLK_TC_BARRIER)
1029                 rwbs[i++] = 'B';
1030         if (tc & BLK_TC_SYNC)
1031                 rwbs[i++] = 'S';
1032         if (tc & BLK_TC_META)
1033                 rwbs[i++] = 'M';
1034 out:
1035         rwbs[i] = '\0';
1036 }
1037
1038 static inline
1039 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1040 {
1041         return (const struct blk_io_trace *)ent;
1042 }
1043
1044 static inline const void *pdu_start(const struct trace_entry *ent)
1045 {
1046         return te_blk_io_trace(ent) + 1;
1047 }
1048
1049 static inline u32 t_action(const struct trace_entry *ent)
1050 {
1051         return te_blk_io_trace(ent)->action;
1052 }
1053
1054 static inline u32 t_bytes(const struct trace_entry *ent)
1055 {
1056         return te_blk_io_trace(ent)->bytes;
1057 }
1058
1059 static inline u32 t_sec(const struct trace_entry *ent)
1060 {
1061         return te_blk_io_trace(ent)->bytes >> 9;
1062 }
1063
1064 static inline unsigned long long t_sector(const struct trace_entry *ent)
1065 {
1066         return te_blk_io_trace(ent)->sector;
1067 }
1068
1069 static inline __u16 t_error(const struct trace_entry *ent)
1070 {
1071         return te_blk_io_trace(ent)->error;
1072 }
1073
1074 static __u64 get_pdu_int(const struct trace_entry *ent)
1075 {
1076         const __u64 *val = pdu_start(ent);
1077         return be64_to_cpu(*val);
1078 }
1079
1080 static void get_pdu_remap(const struct trace_entry *ent,
1081                           struct blk_io_trace_remap *r)
1082 {
1083         const struct blk_io_trace_remap *__r = pdu_start(ent);
1084         __u64 sector_from = __r->sector_from;
1085
1086         r->device_from = be32_to_cpu(__r->device_from);
1087         r->device_to   = be32_to_cpu(__r->device_to);
1088         r->sector_from = be64_to_cpu(sector_from);
1089 }
1090
1091 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1092
1093 static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1094 {
1095         char rwbs[6];
1096         unsigned long long ts  = iter->ts;
1097         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1098         unsigned secs          = (unsigned long)ts;
1099         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1100
1101         fill_rwbs(rwbs, t);
1102
1103         return trace_seq_printf(&iter->seq,
1104                                 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1105                                 MAJOR(t->device), MINOR(t->device), iter->cpu,
1106                                 secs, nsec_rem, iter->ent->pid, act, rwbs);
1107 }
1108
1109 static int blk_log_action(struct trace_iterator *iter, const char *act)
1110 {
1111         char rwbs[6];
1112         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1113
1114         fill_rwbs(rwbs, t);
1115         return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1116                                 MAJOR(t->device), MINOR(t->device), act, rwbs);
1117 }
1118
1119 static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1120 {
1121         const unsigned char *pdu_buf;
1122         int pdu_len;
1123         int i, end, ret;
1124
1125         pdu_buf = pdu_start(ent);
1126         pdu_len = te_blk_io_trace(ent)->pdu_len;
1127
1128         if (!pdu_len)
1129                 return 1;
1130
1131         /* find the last zero that needs to be printed */
1132         for (end = pdu_len - 1; end >= 0; end--)
1133                 if (pdu_buf[end])
1134                         break;
1135         end++;
1136
1137         if (!trace_seq_putc(s, '('))
1138                 return 0;
1139
1140         for (i = 0; i < pdu_len; i++) {
1141
1142                 ret = trace_seq_printf(s, "%s%02x",
1143                                        i == 0 ? "" : " ", pdu_buf[i]);
1144                 if (!ret)
1145                         return ret;
1146
1147                 /*
1148                  * stop when the rest is just zeroes and indicate so
1149                  * with a ".." appended
1150                  */
1151                 if (i == end && end != pdu_len - 1)
1152                         return trace_seq_puts(s, " ..) ");
1153         }
1154
1155         return trace_seq_puts(s, ") ");
1156 }
1157
1158 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1159 {
1160         char cmd[TASK_COMM_LEN];
1161
1162         trace_find_cmdline(ent->pid, cmd);
1163
1164         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1165                 int ret;
1166
1167                 ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1168                 if (!ret)
1169                         return 0;
1170                 ret = blk_log_dump_pdu(s, ent);
1171                 if (!ret)
1172                         return 0;
1173                 return trace_seq_printf(s, "[%s]\n", cmd);
1174         } else {
1175                 if (t_sec(ent))
1176                         return trace_seq_printf(s, "%llu + %u [%s]\n",
1177                                                 t_sector(ent), t_sec(ent), cmd);
1178                 return trace_seq_printf(s, "[%s]\n", cmd);
1179         }
1180 }
1181
1182 static int blk_log_with_error(struct trace_seq *s,
1183                               const struct trace_entry *ent)
1184 {
1185         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1186                 int ret;
1187
1188                 ret = blk_log_dump_pdu(s, ent);
1189                 if (ret)
1190                         return trace_seq_printf(s, "[%d]\n", t_error(ent));
1191                 return 0;
1192         } else {
1193                 if (t_sec(ent))
1194                         return trace_seq_printf(s, "%llu + %u [%d]\n",
1195                                                 t_sector(ent),
1196                                                 t_sec(ent), t_error(ent));
1197                 return trace_seq_printf(s, "%llu [%d]\n",
1198                                         t_sector(ent), t_error(ent));
1199         }
1200 }
1201
1202 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1203 {
1204         struct blk_io_trace_remap r = { .device_from = 0, };
1205
1206         get_pdu_remap(ent, &r);
1207         return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1208                                 t_sector(ent), t_sec(ent),
1209                                 MAJOR(r.device_from), MINOR(r.device_from),
1210                                 (unsigned long long)r.sector_from);
1211 }
1212
1213 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1214 {
1215         char cmd[TASK_COMM_LEN];
1216
1217         trace_find_cmdline(ent->pid, cmd);
1218
1219         return trace_seq_printf(s, "[%s]\n", cmd);
1220 }
1221
1222 static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1223 {
1224         char cmd[TASK_COMM_LEN];
1225
1226         trace_find_cmdline(ent->pid, cmd);
1227
1228         return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1229 }
1230
1231 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1232 {
1233         char cmd[TASK_COMM_LEN];
1234
1235         trace_find_cmdline(ent->pid, cmd);
1236
1237         return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1238                                 get_pdu_int(ent), cmd);
1239 }
1240
1241 static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1242 {
1243         int ret;
1244         const struct blk_io_trace *t = te_blk_io_trace(ent);
1245
1246         ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1247         if (ret)
1248                 return trace_seq_putc(s, '\n');
1249         return ret;
1250 }
1251
1252 /*
1253  * struct tracer operations
1254  */
1255
1256 static void blk_tracer_print_header(struct seq_file *m)
1257 {
1258         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1259                 return;
1260         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1261                     "#  |     |     |           |   |   |\n");
1262 }
1263
1264 static void blk_tracer_start(struct trace_array *tr)
1265 {
1266         blk_tracer_enabled = true;
1267 }
1268
1269 static int blk_tracer_init(struct trace_array *tr)
1270 {
1271         blk_tr = tr;
1272         blk_tracer_start(tr);
1273         return 0;
1274 }
1275
1276 static void blk_tracer_stop(struct trace_array *tr)
1277 {
1278         blk_tracer_enabled = false;
1279 }
1280
1281 static void blk_tracer_reset(struct trace_array *tr)
1282 {
1283         blk_tracer_stop(tr);
1284 }
1285
1286 static const struct {
1287         const char *act[2];
1288         int        (*print)(struct trace_seq *s, const struct trace_entry *ent);
1289 } what2act[] = {
1290         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1291         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1292         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1293         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1294         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1295         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1296         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1297         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1298         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1299         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1300         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1301         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1302         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1303         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1304         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1305 };
1306
1307 static enum print_line_t print_one_line(struct trace_iterator *iter,
1308                                         bool classic)
1309 {
1310         struct trace_seq *s = &iter->seq;
1311         const struct blk_io_trace *t;
1312         u16 what;
1313         int ret;
1314         bool long_act;
1315         blk_log_action_t *log_action;
1316
1317         t          = te_blk_io_trace(iter->ent);
1318         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1319         long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1320         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1321
1322         if (t->action == BLK_TN_MESSAGE) {
1323                 ret = log_action(iter, long_act ? "message" : "m");
1324                 if (ret)
1325                         ret = blk_log_msg(s, iter->ent);
1326                 goto out;
1327         }
1328
1329         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1330                 ret = trace_seq_printf(s, "Unknown action %x\n", what);
1331         else {
1332                 ret = log_action(iter, what2act[what].act[long_act]);
1333                 if (ret)
1334                         ret = what2act[what].print(s, iter->ent);
1335         }
1336 out:
1337         return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1338 }
1339
1340 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1341                                                int flags, struct trace_event *event)
1342 {
1343         return print_one_line(iter, false);
1344 }
1345
1346 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1347 {
1348         struct trace_seq *s = &iter->seq;
1349         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1350         const int offset = offsetof(struct blk_io_trace, sector);
1351         struct blk_io_trace old = {
1352                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1353                 .time     = iter->ts,
1354         };
1355
1356         if (!trace_seq_putmem(s, &old, offset))
1357                 return 0;
1358         return trace_seq_putmem(s, &t->sector,
1359                                 sizeof(old) - offset + t->pdu_len);
1360 }
1361
1362 static enum print_line_t
1363 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1364                              struct trace_event *event)
1365 {
1366         return blk_trace_synthesize_old_trace(iter) ?
1367                         TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1368 }
1369
1370 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1371 {
1372         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1373                 return TRACE_TYPE_UNHANDLED;
1374
1375         return print_one_line(iter, true);
1376 }
1377
1378 static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
1379 {
1380         /* don't output context-info for blk_classic output */
1381         if (bit == TRACE_BLK_OPT_CLASSIC) {
1382                 if (set)
1383                         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1384                 else
1385                         trace_flags |= TRACE_ITER_CONTEXT_INFO;
1386         }
1387         return 0;
1388 }
1389
1390 static struct tracer blk_tracer __read_mostly = {
1391         .name           = "blk",
1392         .init           = blk_tracer_init,
1393         .reset          = blk_tracer_reset,
1394         .start          = blk_tracer_start,
1395         .stop           = blk_tracer_stop,
1396         .print_header   = blk_tracer_print_header,
1397         .print_line     = blk_tracer_print_line,
1398         .flags          = &blk_tracer_flags,
1399         .set_flag       = blk_tracer_set_flag,
1400 };
1401
1402 static struct trace_event_functions trace_blk_event_funcs = {
1403         .trace          = blk_trace_event_print,
1404         .binary         = blk_trace_event_print_binary,
1405 };
1406
1407 static struct trace_event trace_blk_event = {
1408         .type           = TRACE_BLK,
1409         .funcs          = &trace_blk_event_funcs,
1410 };
1411
1412 static int __init init_blk_tracer(void)
1413 {
1414         if (!register_ftrace_event(&trace_blk_event)) {
1415                 pr_warning("Warning: could not register block events\n");
1416                 return 1;
1417         }
1418
1419         if (register_tracer(&blk_tracer) != 0) {
1420                 pr_warning("Warning: could not register the block tracer\n");
1421                 unregister_ftrace_event(&trace_blk_event);
1422                 return 1;
1423         }
1424
1425         return 0;
1426 }
1427
1428 device_initcall(init_blk_tracer);
1429
1430 static int blk_trace_remove_queue(struct request_queue *q)
1431 {
1432         struct blk_trace *bt;
1433
1434         bt = xchg(&q->blk_trace, NULL);
1435         if (bt == NULL)
1436                 return -EINVAL;
1437
1438         if (atomic_dec_and_test(&blk_probes_ref))
1439                 blk_unregister_tracepoints();
1440
1441         blk_trace_free(bt);
1442         return 0;
1443 }
1444
1445 /*
1446  * Setup everything required to start tracing
1447  */
1448 static int blk_trace_setup_queue(struct request_queue *q,
1449                                  struct block_device *bdev)
1450 {
1451         struct blk_trace *old_bt, *bt = NULL;
1452         int ret = -ENOMEM;
1453
1454         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1455         if (!bt)
1456                 return -ENOMEM;
1457
1458         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1459         if (!bt->msg_data)
1460                 goto free_bt;
1461
1462         bt->dev = bdev->bd_dev;
1463         bt->act_mask = (u16)-1;
1464
1465         blk_trace_setup_lba(bt, bdev);
1466
1467         old_bt = xchg(&q->blk_trace, bt);
1468         if (old_bt != NULL) {
1469                 (void)xchg(&q->blk_trace, old_bt);
1470                 ret = -EBUSY;
1471                 goto free_bt;
1472         }
1473
1474         if (atomic_inc_return(&blk_probes_ref) == 1)
1475                 blk_register_tracepoints();
1476         return 0;
1477
1478 free_bt:
1479         blk_trace_free(bt);
1480         return ret;
1481 }
1482
1483 /*
1484  * sysfs interface to enable and configure tracing
1485  */
1486
1487 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1488                                          struct device_attribute *attr,
1489                                          char *buf);
1490 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1491                                           struct device_attribute *attr,
1492                                           const char *buf, size_t count);
1493 #define BLK_TRACE_DEVICE_ATTR(_name) \
1494         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1495                     sysfs_blk_trace_attr_show, \
1496                     sysfs_blk_trace_attr_store)
1497
1498 static BLK_TRACE_DEVICE_ATTR(enable);
1499 static BLK_TRACE_DEVICE_ATTR(act_mask);
1500 static BLK_TRACE_DEVICE_ATTR(pid);
1501 static BLK_TRACE_DEVICE_ATTR(start_lba);
1502 static BLK_TRACE_DEVICE_ATTR(end_lba);
1503
1504 static struct attribute *blk_trace_attrs[] = {
1505         &dev_attr_enable.attr,
1506         &dev_attr_act_mask.attr,
1507         &dev_attr_pid.attr,
1508         &dev_attr_start_lba.attr,
1509         &dev_attr_end_lba.attr,
1510         NULL
1511 };
1512
1513 struct attribute_group blk_trace_attr_group = {
1514         .name  = "trace",
1515         .attrs = blk_trace_attrs,
1516 };
1517
1518 static const struct {
1519         int mask;
1520         const char *str;
1521 } mask_maps[] = {
1522         { BLK_TC_READ,          "read"          },
1523         { BLK_TC_WRITE,         "write"         },
1524         { BLK_TC_BARRIER,       "barrier"       },
1525         { BLK_TC_SYNC,          "sync"          },
1526         { BLK_TC_QUEUE,         "queue"         },
1527         { BLK_TC_REQUEUE,       "requeue"       },
1528         { BLK_TC_ISSUE,         "issue"         },
1529         { BLK_TC_COMPLETE,      "complete"      },
1530         { BLK_TC_FS,            "fs"            },
1531         { BLK_TC_PC,            "pc"            },
1532         { BLK_TC_AHEAD,         "ahead"         },
1533         { BLK_TC_META,          "meta"          },
1534         { BLK_TC_DISCARD,       "discard"       },
1535         { BLK_TC_DRV_DATA,      "drv_data"      },
1536 };
1537
1538 static int blk_trace_str2mask(const char *str)
1539 {
1540         int i;
1541         int mask = 0;
1542         char *buf, *s, *token;
1543
1544         buf = kstrdup(str, GFP_KERNEL);
1545         if (buf == NULL)
1546                 return -ENOMEM;
1547         s = strstrip(buf);
1548
1549         while (1) {
1550                 token = strsep(&s, ",");
1551                 if (token == NULL)
1552                         break;
1553
1554                 if (*token == '\0')
1555                         continue;
1556
1557                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1558                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1559                                 mask |= mask_maps[i].mask;
1560                                 break;
1561                         }
1562                 }
1563                 if (i == ARRAY_SIZE(mask_maps)) {
1564                         mask = -EINVAL;
1565                         break;
1566                 }
1567         }
1568         kfree(buf);
1569
1570         return mask;
1571 }
1572
1573 static ssize_t blk_trace_mask2str(char *buf, int mask)
1574 {
1575         int i;
1576         char *p = buf;
1577
1578         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1579                 if (mask & mask_maps[i].mask) {
1580                         p += sprintf(p, "%s%s",
1581                                     (p == buf) ? "" : ",", mask_maps[i].str);
1582                 }
1583         }
1584         *p++ = '\n';
1585
1586         return p - buf;
1587 }
1588
1589 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1590 {
1591         if (bdev->bd_disk == NULL)
1592                 return NULL;
1593
1594         return bdev_get_queue(bdev);
1595 }
1596
1597 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1598                                          struct device_attribute *attr,
1599                                          char *buf)
1600 {
1601         struct hd_struct *p = dev_to_part(dev);
1602         struct request_queue *q;
1603         struct block_device *bdev;
1604         ssize_t ret = -ENXIO;
1605
1606         lock_kernel();
1607         bdev = bdget(part_devt(p));
1608         if (bdev == NULL)
1609                 goto out_unlock_kernel;
1610
1611         q = blk_trace_get_queue(bdev);
1612         if (q == NULL)
1613                 goto out_bdput;
1614
1615         mutex_lock(&bdev->bd_mutex);
1616
1617         if (attr == &dev_attr_enable) {
1618                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1619                 goto out_unlock_bdev;
1620         }
1621
1622         if (q->blk_trace == NULL)
1623                 ret = sprintf(buf, "disabled\n");
1624         else if (attr == &dev_attr_act_mask)
1625                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1626         else if (attr == &dev_attr_pid)
1627                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1628         else if (attr == &dev_attr_start_lba)
1629                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1630         else if (attr == &dev_attr_end_lba)
1631                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1632
1633 out_unlock_bdev:
1634         mutex_unlock(&bdev->bd_mutex);
1635 out_bdput:
1636         bdput(bdev);
1637 out_unlock_kernel:
1638         unlock_kernel();
1639         return ret;
1640 }
1641
1642 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1643                                           struct device_attribute *attr,
1644                                           const char *buf, size_t count)
1645 {
1646         struct block_device *bdev;
1647         struct request_queue *q;
1648         struct hd_struct *p;
1649         u64 value;
1650         ssize_t ret = -EINVAL;
1651
1652         if (count == 0)
1653                 goto out;
1654
1655         if (attr == &dev_attr_act_mask) {
1656                 if (sscanf(buf, "%llx", &value) != 1) {
1657                         /* Assume it is a list of trace category names */
1658                         ret = blk_trace_str2mask(buf);
1659                         if (ret < 0)
1660                                 goto out;
1661                         value = ret;
1662                 }
1663         } else if (sscanf(buf, "%llu", &value) != 1)
1664                 goto out;
1665
1666         ret = -ENXIO;
1667
1668         lock_kernel();
1669         p = dev_to_part(dev);
1670         bdev = bdget(part_devt(p));
1671         if (bdev == NULL)
1672                 goto out_unlock_kernel;
1673
1674         q = blk_trace_get_queue(bdev);
1675         if (q == NULL)
1676                 goto out_bdput;
1677
1678         mutex_lock(&bdev->bd_mutex);
1679
1680         if (attr == &dev_attr_enable) {
1681                 if (value)
1682                         ret = blk_trace_setup_queue(q, bdev);
1683                 else
1684                         ret = blk_trace_remove_queue(q);
1685                 goto out_unlock_bdev;
1686         }
1687
1688         ret = 0;
1689         if (q->blk_trace == NULL)
1690                 ret = blk_trace_setup_queue(q, bdev);
1691
1692         if (ret == 0) {
1693                 if (attr == &dev_attr_act_mask)
1694                         q->blk_trace->act_mask = value;
1695                 else if (attr == &dev_attr_pid)
1696                         q->blk_trace->pid = value;
1697                 else if (attr == &dev_attr_start_lba)
1698                         q->blk_trace->start_lba = value;
1699                 else if (attr == &dev_attr_end_lba)
1700                         q->blk_trace->end_lba = value;
1701         }
1702
1703 out_unlock_bdev:
1704         mutex_unlock(&bdev->bd_mutex);
1705 out_bdput:
1706         bdput(bdev);
1707 out_unlock_kernel:
1708         unlock_kernel();
1709 out:
1710         return ret ? ret : count;
1711 }
1712
1713 int blk_trace_init_sysfs(struct device *dev)
1714 {
1715         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1716 }
1717
1718 void blk_trace_remove_sysfs(struct device *dev)
1719 {
1720         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1721 }
1722
1723 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1724
1725 #ifdef CONFIG_EVENT_TRACING
1726
1727 void blk_dump_cmd(char *buf, struct request *rq)
1728 {
1729         int i, end;
1730         int len = rq->cmd_len;
1731         unsigned char *cmd = rq->cmd;
1732
1733         if (!blk_pc_request(rq)) {
1734                 buf[0] = '\0';
1735                 return;
1736         }
1737
1738         for (end = len - 1; end >= 0; end--)
1739                 if (cmd[end])
1740                         break;
1741         end++;
1742
1743         for (i = 0; i < len; i++) {
1744                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1745                 if (i == end && end != len - 1) {
1746                         sprintf(buf, " ..");
1747                         break;
1748                 }
1749         }
1750 }
1751
1752 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1753 {
1754         int i = 0;
1755
1756         if (rw & WRITE)
1757                 rwbs[i++] = 'W';
1758         else if (rw & 1 << BIO_RW_DISCARD)
1759                 rwbs[i++] = 'D';
1760         else if (bytes)
1761                 rwbs[i++] = 'R';
1762         else
1763                 rwbs[i++] = 'N';
1764
1765         if (rw & 1 << BIO_RW_AHEAD)
1766                 rwbs[i++] = 'A';
1767         if (rw & 1 << BIO_RW_BARRIER)
1768                 rwbs[i++] = 'B';
1769         if (rw & 1 << BIO_RW_SYNCIO)
1770                 rwbs[i++] = 'S';
1771         if (rw & 1 << BIO_RW_META)
1772                 rwbs[i++] = 'M';
1773
1774         rwbs[i] = '\0';
1775 }
1776
1777 void blk_fill_rwbs_rq(char *rwbs, struct request *rq)
1778 {
1779         int rw = rq->cmd_flags & 0x03;
1780         int bytes;
1781
1782         if (blk_discard_rq(rq))
1783                 rw |= (1 << BIO_RW_DISCARD);
1784
1785         bytes = blk_rq_bytes(rq);
1786
1787         blk_fill_rwbs(rwbs, rw, bytes);
1788 }
1789
1790 #endif /* CONFIG_EVENT_TRACING */
1791