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/time.h>
  27 #include <linux/uaccess.h>
  28
  29 #include <trace/events/block.h>
  30
  31 #include "trace_output.h"
  32
  33 #ifdef CONFIG_BLK_DEV_IO_TRACE
  34
  35 static unsigned int blktrace_seq __read_mostly = 1;
  36
  37 static struct trace_array *blk_tr;
  38 static bool blk_tracer_enabled __read_mostly;
  39
  40 /* Select an alternative, minimalistic output than the original one */
  41 #define TRACE_BLK_OPT_CLASSIC   0x1
  42
  43 static struct tracer_opt blk_tracer_opts[] = {
  44         /* Default disable the minimalistic output */
  45         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
  46         { }
  47 };
  48
  49 static struct tracer_flags blk_tracer_flags = {
  50         .val  = 0,
  51         .opts = blk_tracer_opts,
  52 };
  53
  54 /* Global reference count of probes */
  55 static atomic_t blk_probes_ref = ATOMIC_INIT(0);
  56
  57 static void blk_register_tracepoints(void);
  58 static void blk_unregister_tracepoints(void);
  59
  60 /*
  61  * Send out a notify message.
  62  */
  63 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
  64                        const void *data, size_t len)
  65 {
  66         struct blk_io_trace *t;
  67         struct ring_buffer_event *event = NULL;
  68         struct ring_buffer *buffer = NULL;
  69         int pc = 0;
  70         int cpu = smp_processor_id();
  71         bool blk_tracer = blk_tracer_enabled;
  72
  73         if (blk_tracer) {
  74                 buffer = blk_tr->buffer;
  75                 pc = preempt_count();
  76                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
  77                                                   sizeof(*t) + len,
  78                                                   0, pc);
  79                 if (!event)
  80                         return;
  81                 t = ring_buffer_event_data(event);
  82                 goto record_it;
  83         }
  84
  85         if (!bt->rchan)
  86                 return;
  87
  88         t = relay_reserve(bt->rchan, sizeof(*t) + len);
  89         if (t) {
  90                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
  91                 t->time = ktime_to_ns(ktime_get());
  92 record_it:
  93                 t->device = bt->dev;
  94                 t->action = action;
  95                 t->pid = pid;
  96                 t->cpu = cpu;
  97                 t->pdu_len = len;
  98                 memcpy((void *) t + sizeof(*t), data, len);
  99
 100                 if (blk_tracer)
 101                         trace_buffer_unlock_commit(buffer, event, 0, pc);
 102         }
 103 }
 104
 105 /*
 106  * Send out a notify for this process, if we haven't done so since a trace
 107  * started
 108  */
 109 static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
 110 {
 111         tsk->btrace_seq = blktrace_seq;
 112         trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));
 113 }
 114
 115 static void trace_note_time(struct blk_trace *bt)
 116 {
 117         struct timespec now;
 118         unsigned long flags;
 119         u32 words[2];
 120
 121         getnstimeofday(&now);
 122         words[0] = now.tv_sec;
 123         words[1] = now.tv_nsec;
 124
 125         local_irq_save(flags);
 126         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
 127         local_irq_restore(flags);
 128 }
 129
 130 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 131 {
 132         int n;
 133         va_list args;
 134         unsigned long flags;
 135         char *buf;
 136
 137         if (unlikely(bt->trace_state != Blktrace_running &&
 138                      !blk_tracer_enabled))
 139                 return;
 140
 141         /*
 142          * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
 143          * message to the trace.
 144          */
 145         if (!(bt->act_mask & BLK_TC_NOTIFY))
 146                 return;
 147
 148         local_irq_save(flags);
 149         buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
 150         va_start(args, fmt);
 151         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 152         va_end(args);
 153
 154         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
 155         local_irq_restore(flags);
 156 }
 157 EXPORT_SYMBOL_GPL(__trace_note_message);
 158
 159 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
 160                          pid_t pid)
 161 {
 162         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
 163                 return 1;
 164         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
 165                 return 1;
 166         if (bt->pid && pid != bt->pid)
 167                 return 1;
 168
 169         return 0;
 170 }
 171
 172 /*
 173  * Data direction bit lookup
 174  */
 175 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
 176                                  BLK_TC_ACT(BLK_TC_WRITE) };
 177
 178 #define BLK_TC_RAHEAD           BLK_TC_AHEAD
 179
 180 /* The ilog2() calls fall out because they're constant */
 181 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
 182           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
 183
 184 /*
 185  * The worker for the various blk_add_trace*() types. Fills out a
 186  * blk_io_trace structure and places it in a per-cpu subbuffer.
 187  */
 188 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 189                      int rw, u32 what, int error, int pdu_len, void *pdu_data)
 190 {
 191         struct task_struct *tsk = current;
 192         struct ring_buffer_event *event = NULL;
 193         struct ring_buffer *buffer = NULL;
 194         struct blk_io_trace *t;
 195         unsigned long flags = 0;
 196         unsigned long *sequence;
 197         pid_t pid;
 198         int cpu, pc = 0;
 199         bool blk_tracer = blk_tracer_enabled;
 200
 201         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
 202                 return;
 203
 204         what |= ddir_act[rw & WRITE];
 205         what |= MASK_TC_BIT(rw, SYNC);
 206         what |= MASK_TC_BIT(rw, RAHEAD);
 207         what |= MASK_TC_BIT(rw, META);
 208         what |= MASK_TC_BIT(rw, DISCARD);
 209
 210         pid = tsk->pid;
 211         if (act_log_check(bt, what, sector, pid))
 212                 return;
 213         cpu = raw_smp_processor_id();
 214
 215         if (blk_tracer) {
 216                 tracing_record_cmdline(current);
 217
 218                 buffer = blk_tr->buffer;
 219                 pc = preempt_count();
 220                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 221                                                   sizeof(*t) + pdu_len,
 222                                                   0, pc);
 223                 if (!event)
 224                         return;
 225                 t = ring_buffer_event_data(event);
 226                 goto record_it;
 227         }
 228
 229         /*
 230          * A word about the locking here - we disable interrupts to reserve
 231          * some space in the relay per-cpu buffer, to prevent an irq
 232          * from coming in and stepping on our toes.
 233          */
 234         local_irq_save(flags);
 235
 236         if (unlikely(tsk->btrace_seq != blktrace_seq))
 237                 trace_note_tsk(bt, tsk);
 238
 239         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
 240         if (t) {
 241                 sequence = per_cpu_ptr(bt->sequence, cpu);
 242
 243                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 244                 t->sequence = ++(*sequence);
 245                 t->time = ktime_to_ns(ktime_get());
 246 record_it:
 247                 /*
 248                  * These two are not needed in ftrace as they are in the
 249                  * generic trace_entry, filled by tracing_generic_entry_update,
 250                  * but for the trace_event->bin() synthesizer benefit we do it
 251                  * here too.
 252                  */
 253                 t->cpu = cpu;
 254                 t->pid = pid;
 255
 256                 t->sector = sector;
 257                 t->bytes = bytes;
 258                 t->action = what;
 259                 t->device = bt->dev;
 260                 t->error = error;
 261                 t->pdu_len = pdu_len;
 262
 263                 if (pdu_len)
 264                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
 265
 266                 if (blk_tracer) {
 267                         trace_buffer_unlock_commit(buffer, event, 0, pc);
 268                         return;
 269                 }
 270         }
 271
 272         local_irq_restore(flags);
 273 }
 274
 275 static struct dentry *blk_tree_root;
 276 static DEFINE_MUTEX(blk_tree_mutex);
 277
 278 static void blk_trace_free(struct blk_trace *bt)
 279 {
 280         debugfs_remove(bt->msg_file);
 281         debugfs_remove(bt->dropped_file);
 282         relay_close(bt->rchan);
 283         debugfs_remove(bt->dir);
 284         free_percpu(bt->sequence);
 285         free_percpu(bt->msg_data);
 286         kfree(bt);
 287 }
 288
 289 static void blk_trace_cleanup(struct blk_trace *bt)
 290 {
 291         blk_trace_free(bt);
 292         if (atomic_dec_and_test(&blk_probes_ref))
 293                 blk_unregister_tracepoints();
 294 }
 295
 296 int blk_trace_remove(struct request_queue *q)
 297 {
 298         struct blk_trace *bt;
 299
 300         bt = xchg(&q->blk_trace, NULL);
 301         if (!bt)
 302                 return -EINVAL;
 303
 304         if (bt->trace_state != Blktrace_running)
 305                 blk_trace_cleanup(bt);
 306
 307         return 0;
 308 }
 309 EXPORT_SYMBOL_GPL(blk_trace_remove);
 310
 311 static int blk_dropped_open(struct inode *inode, struct file *filp)
 312 {
 313         filp->private_data = inode->i_private;
 314
 315         return 0;
 316 }
 317
 318 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
 319                                 size_t count, loff_t *ppos)
 320 {
 321         struct blk_trace *bt = filp->private_data;
 322         char buf[16];
 323
 324         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
 325
 326         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 327 }
 328
 329 static const struct file_operations blk_dropped_fops = {
 330         .owner =        THIS_MODULE,
 331         .open =         blk_dropped_open,
 332         .read =         blk_dropped_read,
 333         .llseek =       default_llseek,
 334 };
 335
 336 static int blk_msg_open(struct inode *inode, struct file *filp)
 337 {
 338         filp->private_data = inode->i_private;
 339
 340         return 0;
 341 }
 342
 343 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 344                                 size_t count, loff_t *ppos)
 345 {
 346         char *msg;
 347         struct blk_trace *bt;
 348
 349         if (count >= BLK_TN_MAX_MSG)
 350                 return -EINVAL;
 351
 352         msg = kmalloc(count + 1, GFP_KERNEL);
 353         if (msg == NULL)
 354                 return -ENOMEM;
 355
 356         if (copy_from_user(msg, buffer, count)) {
 357                 kfree(msg);
 358                 return -EFAULT;
 359         }
 360
 361         msg[count] = '\0';
 362         bt = filp->private_data;
 363         __trace_note_message(bt, "%s", msg);
 364         kfree(msg);
 365
 366         return count;
 367 }
 368
 369 static const struct file_operations blk_msg_fops = {
 370         .owner =        THIS_MODULE,
 371         .open =         blk_msg_open,
 372         .write =        blk_msg_write,
 373         .llseek =       noop_llseek,
 374 };
 375
 376 /*
 377  * Keep track of how many times we encountered a full subbuffer, to aid
 378  * the user space app in telling how many lost events there were.
 379  */
 380 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
 381                                      void *prev_subbuf, size_t prev_padding)
 382 {
 383         struct blk_trace *bt;
 384
 385         if (!relay_buf_full(buf))
 386                 return 1;
 387
 388         bt = buf->chan->private_data;
 389         atomic_inc(&bt->dropped);
 390         return 0;
 391 }
 392
 393 static int blk_remove_buf_file_callback(struct dentry *dentry)
 394 {
 395         debugfs_remove(dentry);
 396
 397         return 0;
 398 }
 399
 400 static struct dentry *blk_create_buf_file_callback(const char *filename,
 401                                                    struct dentry *parent,
 402                                                    int mode,
 403                                                    struct rchan_buf *buf,
 404                                                    int *is_global)
 405 {
 406         return debugfs_create_file(filename, mode, parent, buf,
 407                                         &relay_file_operations);
 408 }
 409
 410 static struct rchan_callbacks blk_relay_callbacks = {
 411         .subbuf_start           = blk_subbuf_start_callback,
 412         .create_buf_file        = blk_create_buf_file_callback,
 413         .remove_buf_file        = blk_remove_buf_file_callback,
 414 };
 415
 416 static void blk_trace_setup_lba(struct blk_trace *bt,
 417                                 struct block_device *bdev)
 418 {
 419         struct hd_struct *part = NULL;
 420
 421         if (bdev)
 422                 part = bdev->bd_part;
 423
 424         if (part) {
 425                 bt->start_lba = part->start_sect;
 426                 bt->end_lba = part->start_sect + part->nr_sects;
 427         } else {
 428                 bt->start_lba = 0;
 429                 bt->end_lba = -1ULL;
 430         }
 431 }
 432
 433 /*
 434  * Setup everything required to start tracing
 435  */
 436 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 437                        struct block_device *bdev,
 438                        struct blk_user_trace_setup *buts)
 439 {
 440         struct blk_trace *old_bt, *bt = NULL;
 441         struct dentry *dir = NULL;
 442         int ret, i;
 443
 444         if (!buts->buf_size || !buts->buf_nr)
 445                 return -EINVAL;
 446
 447         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 448         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 449
 450         /*
 451          * some device names have larger paths - convert the slashes
 452          * to underscores for this to work as expected
 453          */
 454         for (i = 0; i < strlen(buts->name); i++)
 455                 if (buts->name[i] == '/')
 456                         buts->name[i] = '_';
 457
 458         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 459         if (!bt)
 460                 return -ENOMEM;
 461
 462         ret = -ENOMEM;
 463         bt->sequence = alloc_percpu(unsigned long);
 464         if (!bt->sequence)
 465                 goto err;
 466
 467         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 468         if (!bt->msg_data)
 469                 goto err;
 470
 471         ret = -ENOENT;
 472
 473         mutex_lock(&blk_tree_mutex);
 474         if (!blk_tree_root) {
 475                 blk_tree_root = debugfs_create_dir("block", NULL);
 476                 if (!blk_tree_root) {
 477                         mutex_unlock(&blk_tree_mutex);
 478                         goto err;
 479                 }
 480         }
 481         mutex_unlock(&blk_tree_mutex);
 482
 483         dir = debugfs_create_dir(buts->name, blk_tree_root);
 484
 485         if (!dir)
 486                 goto err;
 487
 488         bt->dir = dir;
 489         bt->dev = dev;
 490         atomic_set(&bt->dropped, 0);
 491
 492         ret = -EIO;
 493         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 494                                                &blk_dropped_fops);
 495         if (!bt->dropped_file)
 496                 goto err;
 497
 498         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 499         if (!bt->msg_file)
 500                 goto err;
 501
 502         bt->rchan = relay_open("trace", dir, buts->buf_size,
 503                                 buts->buf_nr, &blk_relay_callbacks, bt);
 504         if (!bt->rchan)
 505                 goto err;
 506
 507         bt->act_mask = buts->act_mask;
 508         if (!bt->act_mask)
 509                 bt->act_mask = (u16) -1;
 510
 511         blk_trace_setup_lba(bt, bdev);
 512
 513         /* overwrite with user settings */
 514         if (buts->start_lba)
 515                 bt->start_lba = buts->start_lba;
 516         if (buts->end_lba)
 517                 bt->end_lba = buts->end_lba;
 518
 519         bt->pid = buts->pid;
 520         bt->trace_state = Blktrace_setup;
 521
 522         ret = -EBUSY;
 523         old_bt = xchg(&q->blk_trace, bt);
 524         if (old_bt) {
 525                 (void) xchg(&q->blk_trace, old_bt);
 526                 goto err;
 527         }
 528
 529         if (atomic_inc_return(&blk_probes_ref) == 1)
 530                 blk_register_tracepoints();
 531
 532         return 0;
 533 err:
 534         blk_trace_free(bt);
 535         return ret;
 536 }
 537
 538 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 539                     struct block_device *bdev,
 540                     char __user *arg)
 541 {
 542         struct blk_user_trace_setup buts;
 543         int ret;
 544
 545         ret = copy_from_user(&buts, arg, sizeof(buts));
 546         if (ret)
 547                 return -EFAULT;
 548
 549         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 550         if (ret)
 551                 return ret;
 552
 553         if (copy_to_user(arg, &buts, sizeof(buts))) {
 554                 blk_trace_remove(q);
 555                 return -EFAULT;
 556         }
 557         return 0;
 558 }
 559 EXPORT_SYMBOL_GPL(blk_trace_setup);
 560
 561 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 562 static int compat_blk_trace_setup(struct request_queue *q, char *name,
 563                                   dev_t dev, struct block_device *bdev,
 564                                   char __user *arg)
 565 {
 566         struct blk_user_trace_setup buts;
 567         struct compat_blk_user_trace_setup cbuts;
 568         int ret;
 569
 570         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
 571                 return -EFAULT;
 572
 573         buts = (struct blk_user_trace_setup) {
 574                 .act_mask = cbuts.act_mask,
 575                 .buf_size = cbuts.buf_size,
 576                 .buf_nr = cbuts.buf_nr,
 577                 .start_lba = cbuts.start_lba,
 578                 .end_lba = cbuts.end_lba,
 579                 .pid = cbuts.pid,
 580         };
 581         memcpy(&buts.name, &cbuts.name, 32);
 582
 583         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 584         if (ret)
 585                 return ret;
 586
 587         if (copy_to_user(arg, &buts.name, 32)) {
 588                 blk_trace_remove(q);
 589                 return -EFAULT;
 590         }
 591
 592         return 0;
 593 }
 594 #endif
 595
 596 int blk_trace_startstop(struct request_queue *q, int start)
 597 {
 598         int ret;
 599         struct blk_trace *bt = q->blk_trace;
 600
 601         if (bt == NULL)
 602                 return -EINVAL;
 603
 604         /*
 605          * For starting a trace, we can transition from a setup or stopped
 606          * trace. For stopping a trace, the state must be running
 607          */
 608         ret = -EINVAL;
 609         if (start) {
 610                 if (bt->trace_state == Blktrace_setup ||
 611                     bt->trace_state == Blktrace_stopped) {
 612                         blktrace_seq++;
 613                         smp_mb();
 614                         bt->trace_state = Blktrace_running;
 615
 616                         trace_note_time(bt);
 617                         ret = 0;
 618                 }
 619         } else {
 620                 if (bt->trace_state == Blktrace_running) {
 621                         bt->trace_state = Blktrace_stopped;
 622                         relay_flush(bt->rchan);
 623                         ret = 0;
 624                 }
 625         }
 626
 627         return ret;
 628 }
 629 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 630
 631 /**
 632  * blk_trace_ioctl: - handle the ioctls associated with tracing
 633  * @bdev:       the block device
 634  * @cmd:        the ioctl cmd
 635  * @arg:        the argument data, if any
 636  *
 637  **/
 638 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 639 {
 640         struct request_queue *q;
 641         int ret, start = 0;
 642         char b[BDEVNAME_SIZE];
 643
 644         q = bdev_get_queue(bdev);
 645         if (!q)
 646                 return -ENXIO;
 647
 648         mutex_lock(&bdev->bd_mutex);
 649
 650         switch (cmd) {
 651         case BLKTRACESETUP:
 652                 bdevname(bdev, b);
 653                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 654                 break;
 655 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 656         case BLKTRACESETUP32:
 657                 bdevname(bdev, b);
 658                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 659                 break;
 660 #endif
 661         case BLKTRACESTART:
 662                 start = 1;
 663         case BLKTRACESTOP:
 664                 ret = blk_trace_startstop(q, start);
 665                 break;
 666         case BLKTRACETEARDOWN:
 667                 ret = blk_trace_remove(q);
 668                 break;
 669         default:
 670                 ret = -ENOTTY;
 671                 break;
 672         }
 673
 674         mutex_unlock(&bdev->bd_mutex);
 675         return ret;
 676 }
 677
 678 /**
 679  * blk_trace_shutdown: - stop and cleanup trace structures
 680  * @q:    the request queue associated with the device
 681  *
 682  **/
 683 void blk_trace_shutdown(struct request_queue *q)
 684 {
 685         if (q->blk_trace) {
 686                 blk_trace_startstop(q, 0);
 687                 blk_trace_remove(q);
 688         }
 689 }
 690
 691 /*
 692  * blktrace probes
 693  */
 694
 695 /**
 696  * blk_add_trace_rq - Add a trace for a request oriented action
 697  * @q:          queue the io is for
 698  * @rq:         the source request
 699  * @what:       the action
 700  *
 701  * Description:
 702  *     Records an action against a request. Will log the bio offset + size.
 703  *
 704  **/
 705 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 706                                     u32 what)
 707 {
 708         struct blk_trace *bt = q->blk_trace;
 709         int rw = rq->cmd_flags & 0x03;
 710
 711         if (likely(!bt))
 712                 return;
 713
 714         if (rq->cmd_flags & REQ_DISCARD)
 715                 rw |= REQ_DISCARD;
 716
 717         if (rq->cmd_flags & REQ_SECURE)
 718                 rw |= REQ_SECURE;
 719
 720         if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
 721                 what |= BLK_TC_ACT(BLK_TC_PC);
 722                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), rw,
 723                                 what, rq->errors, rq->cmd_len, rq->cmd);
 724         } else  {
 725                 what |= BLK_TC_ACT(BLK_TC_FS);
 726                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), rw,
 727                                 what, rq->errors, 0, NULL);
 728         }
 729 }
 730
 731 static void blk_add_trace_rq_abort(void *ignore,
 732                                    struct request_queue *q, struct request *rq)
 733 {
 734         blk_add_trace_rq(q, rq, BLK_TA_ABORT);
 735 }
 736
 737 static void blk_add_trace_rq_insert(void *ignore,
 738                                     struct request_queue *q, struct request *rq)
 739 {
 740         blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 741 }
 742
 743 static void blk_add_trace_rq_issue(void *ignore,
 744                                    struct request_queue *q, struct request *rq)
 745 {
 746         blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
 747 }
 748
 749 static void blk_add_trace_rq_requeue(void *ignore,
 750                                      struct request_queue *q,
 751                                      struct request *rq)
 752 {
 753         blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
 754 }
 755
 756 static void blk_add_trace_rq_complete(void *ignore,
 757                                       struct request_queue *q,
 758                                       struct request *rq)
 759 {
 760         blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
 761 }
 762
 763 /**
 764  * blk_add_trace_bio - Add a trace for a bio oriented action
 765  * @q:          queue the io is for
 766  * @bio:        the source bio
 767  * @what:       the action
 768  * @error:      error, if any
 769  *
 770  * Description:
 771  *     Records an action against a bio. Will log the bio offset + size.
 772  *
 773  **/
 774 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 775                               u32 what, int error)
 776 {
 777         struct blk_trace *bt = q->blk_trace;
 778
 779         if (likely(!bt))
 780                 return;
 781
 782         if (!error && !bio_flagged(bio, BIO_UPTODATE))
 783                 error = EIO;
 784
 785         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
 786                         error, 0, NULL);
 787 }
 788
 789 static void blk_add_trace_bio_bounce(void *ignore,
 790                                      struct request_queue *q, struct bio *bio)
 791 {
 792         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
 793 }
 794
 795 static void blk_add_trace_bio_complete(void *ignore,
 796                                        struct request_queue *q, struct bio *bio,
 797                                        int error)
 798 {
 799         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
 800 }
 801
 802 static void blk_add_trace_bio_backmerge(void *ignore,
 803                                         struct request_queue *q,
 804                                         struct bio *bio)
 805 {
 806         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
 807 }
 808
 809 static void blk_add_trace_bio_frontmerge(void *ignore,
 810                                          struct request_queue *q,
 811                                          struct bio *bio)
 812 {
 813         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
 814 }
 815
 816 static void blk_add_trace_bio_queue(void *ignore,
 817                                     struct request_queue *q, struct bio *bio)
 818 {
 819         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
 820 }
 821
 822 static void blk_add_trace_getrq(void *ignore,
 823                                 struct request_queue *q,
 824                                 struct bio *bio, int rw)
 825 {
 826         if (bio)
 827                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
 828         else {
 829                 struct blk_trace *bt = q->blk_trace;
 830
 831                 if (bt)
 832                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
 833         }
 834 }
 835
 836
 837 static void blk_add_trace_sleeprq(void *ignore,
 838                                   struct request_queue *q,
 839                                   struct bio *bio, int rw)
 840 {
 841         if (bio)
 842                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
 843         else {
 844                 struct blk_trace *bt = q->blk_trace;
 845
 846                 if (bt)
 847                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
 848                                         0, 0, NULL);
 849         }
 850 }
 851
 852 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 853 {
 854         struct blk_trace *bt = q->blk_trace;
 855
 856         if (bt)
 857                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
 858 }
 859
 860 static void blk_add_trace_unplug_io(void *ignore, struct request_queue *q)
 861 {
 862         struct blk_trace *bt = q->blk_trace;
 863
 864         if (bt) {
 865                 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
 866                 __be64 rpdu = cpu_to_be64(pdu);
 867
 868                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_IO, 0,
 869                                 sizeof(rpdu), &rpdu);
 870         }
 871 }
 872
 873 static void blk_add_trace_unplug_timer(void *ignore, struct request_queue *q)
 874 {
 875         struct blk_trace *bt = q->blk_trace;
 876
 877         if (bt) {
 878                 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
 879                 __be64 rpdu = cpu_to_be64(pdu);
 880
 881                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_TIMER, 0,
 882                                 sizeof(rpdu), &rpdu);
 883         }
 884 }
 885
 886 static void blk_add_trace_split(void *ignore,
 887                                 struct request_queue *q, struct bio *bio,
 888                                 unsigned int pdu)
 889 {
 890         struct blk_trace *bt = q->blk_trace;
 891
 892         if (bt) {
 893                 __be64 rpdu = cpu_to_be64(pdu);
 894
 895                 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 896                                 BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
 897                                 sizeof(rpdu), &rpdu);
 898         }
 899 }
 900
 901 /**
 902  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
 903  * @ignore:     trace callback data parameter (not used)
 904  * @q:          queue the io is for
 905  * @bio:        the source bio
 906  * @dev:        target device
 907  * @from:       source sector
 908  *
 909  * Description:
 910  *     Device mapper or raid target sometimes need to split a bio because
 911  *     it spans a stripe (or similar). Add a trace for that action.
 912  *
 913  **/
 914 static void blk_add_trace_bio_remap(void *ignore,
 915                                     struct request_queue *q, struct bio *bio,
 916                                     dev_t dev, sector_t from)
 917 {
 918         struct blk_trace *bt = q->blk_trace;
 919         struct blk_io_trace_remap r;
 920
 921         if (likely(!bt))
 922                 return;
 923
 924         r.device_from = cpu_to_be32(dev);
 925         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
 926         r.sector_from = cpu_to_be64(from);
 927
 928         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 929                         BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE),
 930                         sizeof(r), &r);
 931 }
 932
 933 /**
 934  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
 935  * @ignore:     trace callback data parameter (not used)
 936  * @q:          queue the io is for
 937  * @rq:         the source request
 938  * @dev:        target device
 939  * @from:       source sector
 940  *
 941  * Description:
 942  *     Device mapper remaps request to other devices.
 943  *     Add a trace for that action.
 944  *
 945  **/
 946 static void blk_add_trace_rq_remap(void *ignore,
 947                                    struct request_queue *q,
 948                                    struct request *rq, dev_t dev,
 949                                    sector_t from)
 950 {
 951         struct blk_trace *bt = q->blk_trace;
 952         struct blk_io_trace_remap r;
 953
 954         if (likely(!bt))
 955                 return;
 956
 957         r.device_from = cpu_to_be32(dev);
 958         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
 959         r.sector_from = cpu_to_be64(from);
 960
 961         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 962                         rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
 963                         sizeof(r), &r);
 964 }
 965
 966 /**
 967  * blk_add_driver_data - Add binary message with driver-specific data
 968  * @q:          queue the io is for
 969  * @rq:         io request
 970  * @data:       driver-specific data
 971  * @len:        length of driver-specific data
 972  *
 973  * Description:
 974  *     Some drivers might want to write driver-specific data per request.
 975  *
 976  **/
 977 void blk_add_driver_data(struct request_queue *q,
 978                          struct request *rq,
 979                          void *data, size_t len)
 980 {
 981         struct blk_trace *bt = q->blk_trace;
 982
 983         if (likely(!bt))
 984                 return;
 985
 986         if (rq->cmd_type == REQ_TYPE_BLOCK_PC)
 987                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
 988                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 989         else
 990                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
 991                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 992 }
 993 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 994
 995 static void blk_register_tracepoints(void)
 996 {
 997         int ret;
 998
 999         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
1000         WARN_ON(ret);
1001         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1002         WARN_ON(ret);
1003         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1004         WARN_ON(ret);
1005         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1006         WARN_ON(ret);
1007         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1008         WARN_ON(ret);
1009         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1010         WARN_ON(ret);
1011         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1012         WARN_ON(ret);
1013         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1014         WARN_ON(ret);
1015         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1016         WARN_ON(ret);
1017         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1018         WARN_ON(ret);
1019         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1020         WARN_ON(ret);
1021         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1022         WARN_ON(ret);
1023         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1024         WARN_ON(ret);
1025         ret = register_trace_block_unplug_timer(blk_add_trace_unplug_timer, NULL);
1026         WARN_ON(ret);
1027         ret = register_trace_block_unplug_io(blk_add_trace_unplug_io, NULL);
1028         WARN_ON(ret);
1029         ret = register_trace_block_split(blk_add_trace_split, NULL);
1030         WARN_ON(ret);
1031         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1032         WARN_ON(ret);
1033         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1034         WARN_ON(ret);
1035 }
1036
1037 static void blk_unregister_tracepoints(void)
1038 {
1039         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1040         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1041         unregister_trace_block_split(blk_add_trace_split, NULL);
1042         unregister_trace_block_unplug_io(blk_add_trace_unplug_io, NULL);
1043         unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer, NULL);
1044         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1045         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1046         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1047         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1048         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1049         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1050         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1051         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1052         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1053         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1054         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1055         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1056         unregister_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
1057
1058         tracepoint_synchronize_unregister();
1059 }
1060
1061 /*
1062  * struct blk_io_tracer formatting routines
1063  */
1064
1065 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1066 {
1067         int i = 0;
1068         int tc = t->action >> BLK_TC_SHIFT;
1069
1070         if (t->action == BLK_TN_MESSAGE) {
1071                 rwbs[i++] = 'N';
1072                 goto out;
1073         }
1074
1075         if (tc & BLK_TC_DISCARD)
1076                 rwbs[i++] = 'D';
1077         else if (tc & BLK_TC_WRITE)
1078                 rwbs[i++] = 'W';
1079         else if (t->bytes)
1080                 rwbs[i++] = 'R';
1081         else
1082                 rwbs[i++] = 'N';
1083
1084         if (tc & BLK_TC_AHEAD)
1085                 rwbs[i++] = 'A';
1086         if (tc & BLK_TC_BARRIER)
1087                 rwbs[i++] = 'B';
1088         if (tc & BLK_TC_SYNC)
1089                 rwbs[i++] = 'S';
1090         if (tc & BLK_TC_META)
1091                 rwbs[i++] = 'M';
1092 out:
1093         rwbs[i] = '\0';
1094 }
1095
1096 static inline
1097 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1098 {
1099         return (const struct blk_io_trace *)ent;
1100 }
1101
1102 static inline const void *pdu_start(const struct trace_entry *ent)
1103 {
1104         return te_blk_io_trace(ent) + 1;
1105 }
1106
1107 static inline u32 t_action(const struct trace_entry *ent)
1108 {
1109         return te_blk_io_trace(ent)->action;
1110 }
1111
1112 static inline u32 t_bytes(const struct trace_entry *ent)
1113 {
1114         return te_blk_io_trace(ent)->bytes;
1115 }
1116
1117 static inline u32 t_sec(const struct trace_entry *ent)
1118 {
1119         return te_blk_io_trace(ent)->bytes >> 9;
1120 }
1121
1122 static inline unsigned long long t_sector(const struct trace_entry *ent)
1123 {
1124         return te_blk_io_trace(ent)->sector;
1125 }
1126
1127 static inline __u16 t_error(const struct trace_entry *ent)
1128 {
1129         return te_blk_io_trace(ent)->error;
1130 }
1131
1132 static __u64 get_pdu_int(const struct trace_entry *ent)
1133 {
1134         const __u64 *val = pdu_start(ent);
1135         return be64_to_cpu(*val);
1136 }
1137
1138 static void get_pdu_remap(const struct trace_entry *ent,
1139                           struct blk_io_trace_remap *r)
1140 {
1141         const struct blk_io_trace_remap *__r = pdu_start(ent);
1142         __u64 sector_from = __r->sector_from;
1143
1144         r->device_from = be32_to_cpu(__r->device_from);
1145         r->device_to   = be32_to_cpu(__r->device_to);
1146         r->sector_from = be64_to_cpu(sector_from);
1147 }
1148
1149 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1150
1151 static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1152 {
1153         char rwbs[6];
1154         unsigned long long ts  = iter->ts;
1155         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1156         unsigned secs          = (unsigned long)ts;
1157         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1158
1159         fill_rwbs(rwbs, t);
1160
1161         return trace_seq_printf(&iter->seq,
1162                                 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1163                                 MAJOR(t->device), MINOR(t->device), iter->cpu,
1164                                 secs, nsec_rem, iter->ent->pid, act, rwbs);
1165 }
1166
1167 static int blk_log_action(struct trace_iterator *iter, const char *act)
1168 {
1169         char rwbs[6];
1170         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1171
1172         fill_rwbs(rwbs, t);
1173         return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1174                                 MAJOR(t->device), MINOR(t->device), act, rwbs);
1175 }
1176
1177 static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1178 {
1179         const unsigned char *pdu_buf;
1180         int pdu_len;
1181         int i, end, ret;
1182
1183         pdu_buf = pdu_start(ent);
1184         pdu_len = te_blk_io_trace(ent)->pdu_len;
1185
1186         if (!pdu_len)
1187                 return 1;
1188
1189         /* find the last zero that needs to be printed */
1190         for (end = pdu_len - 1; end >= 0; end--)
1191                 if (pdu_buf[end])
1192                         break;
1193         end++;
1194
1195         if (!trace_seq_putc(s, '('))
1196                 return 0;
1197
1198         for (i = 0; i < pdu_len; i++) {
1199
1200                 ret = trace_seq_printf(s, "%s%02x",
1201                                        i == 0 ? "" : " ", pdu_buf[i]);
1202                 if (!ret)
1203                         return ret;
1204
1205                 /*
1206                  * stop when the rest is just zeroes and indicate so
1207                  * with a ".." appended
1208                  */
1209                 if (i == end && end != pdu_len - 1)
1210                         return trace_seq_puts(s, " ..) ");
1211         }
1212
1213         return trace_seq_puts(s, ") ");
1214 }
1215
1216 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1217 {
1218         char cmd[TASK_COMM_LEN];
1219
1220         trace_find_cmdline(ent->pid, cmd);
1221
1222         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1223                 int ret;
1224
1225                 ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1226                 if (!ret)
1227                         return 0;
1228                 ret = blk_log_dump_pdu(s, ent);
1229                 if (!ret)
1230                         return 0;
1231                 return trace_seq_printf(s, "[%s]\n", cmd);
1232         } else {
1233                 if (t_sec(ent))
1234                         return trace_seq_printf(s, "%llu + %u [%s]\n",
1235                                                 t_sector(ent), t_sec(ent), cmd);
1236                 return trace_seq_printf(s, "[%s]\n", cmd);
1237         }
1238 }
1239
1240 static int blk_log_with_error(struct trace_seq *s,
1241                               const struct trace_entry *ent)
1242 {
1243         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1244                 int ret;
1245
1246                 ret = blk_log_dump_pdu(s, ent);
1247                 if (ret)
1248                         return trace_seq_printf(s, "[%d]\n", t_error(ent));
1249                 return 0;
1250         } else {
1251                 if (t_sec(ent))
1252                         return trace_seq_printf(s, "%llu + %u [%d]\n",
1253                                                 t_sector(ent),
1254                                                 t_sec(ent), t_error(ent));
1255                 return trace_seq_printf(s, "%llu [%d]\n",
1256                                         t_sector(ent), t_error(ent));
1257         }
1258 }
1259
1260 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1261 {
1262         struct blk_io_trace_remap r = { .device_from = 0, };
1263
1264         get_pdu_remap(ent, &r);
1265         return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1266                                 t_sector(ent), t_sec(ent),
1267                                 MAJOR(r.device_from), MINOR(r.device_from),
1268                                 (unsigned long long)r.sector_from);
1269 }
1270
1271 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1272 {
1273         char cmd[TASK_COMM_LEN];
1274
1275         trace_find_cmdline(ent->pid, cmd);
1276
1277         return trace_seq_printf(s, "[%s]\n", cmd);
1278 }
1279
1280 static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1281 {
1282         char cmd[TASK_COMM_LEN];
1283
1284         trace_find_cmdline(ent->pid, cmd);
1285
1286         return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1287 }
1288
1289 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1290 {
1291         char cmd[TASK_COMM_LEN];
1292
1293         trace_find_cmdline(ent->pid, cmd);
1294
1295         return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1296                                 get_pdu_int(ent), cmd);
1297 }
1298
1299 static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1300 {
1301         int ret;
1302         const struct blk_io_trace *t = te_blk_io_trace(ent);
1303
1304         ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1305         if (ret)
1306                 return trace_seq_putc(s, '\n');
1307         return ret;
1308 }
1309
1310 /*
1311  * struct tracer operations
1312  */
1313
1314 static void blk_tracer_print_header(struct seq_file *m)
1315 {
1316         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1317                 return;
1318         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1319                     "#  |     |     |           |   |   |\n");
1320 }
1321
1322 static void blk_tracer_start(struct trace_array *tr)
1323 {
1324         blk_tracer_enabled = true;
1325 }
1326
1327 static int blk_tracer_init(struct trace_array *tr)
1328 {
1329         blk_tr = tr;
1330         blk_tracer_start(tr);
1331         return 0;
1332 }
1333
1334 static void blk_tracer_stop(struct trace_array *tr)
1335 {
1336         blk_tracer_enabled = false;
1337 }
1338
1339 static void blk_tracer_reset(struct trace_array *tr)
1340 {
1341         blk_tracer_stop(tr);
1342 }
1343
1344 static const struct {
1345         const char *act[2];
1346         int        (*print)(struct trace_seq *s, const struct trace_entry *ent);
1347 } what2act[] = {
1348         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1349         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1350         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1351         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1352         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1353         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1354         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1355         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1356         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1357         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1358         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1359         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1360         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1361         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1362         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1363 };
1364
1365 static enum print_line_t print_one_line(struct trace_iterator *iter,
1366                                         bool classic)
1367 {
1368         struct trace_seq *s = &iter->seq;
1369         const struct blk_io_trace *t;
1370         u16 what;
1371         int ret;
1372         bool long_act;
1373         blk_log_action_t *log_action;
1374
1375         t          = te_blk_io_trace(iter->ent);
1376         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1377         long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1378         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1379
1380         if (t->action == BLK_TN_MESSAGE) {
1381                 ret = log_action(iter, long_act ? "message" : "m");
1382                 if (ret)
1383                         ret = blk_log_msg(s, iter->ent);
1384                 goto out;
1385         }
1386
1387         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1388                 ret = trace_seq_printf(s, "Unknown action %x\n", what);
1389         else {
1390                 ret = log_action(iter, what2act[what].act[long_act]);
1391                 if (ret)
1392                         ret = what2act[what].print(s, iter->ent);
1393         }
1394 out:
1395         return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1396 }
1397
1398 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1399                                                int flags, struct trace_event *event)
1400 {
1401         return print_one_line(iter, false);
1402 }
1403
1404 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1405 {
1406         struct trace_seq *s = &iter->seq;
1407         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1408         const int offset = offsetof(struct blk_io_trace, sector);
1409         struct blk_io_trace old = {
1410                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1411                 .time     = iter->ts,
1412         };
1413
1414         if (!trace_seq_putmem(s, &old, offset))
1415                 return 0;
1416         return trace_seq_putmem(s, &t->sector,
1417                                 sizeof(old) - offset + t->pdu_len);
1418 }
1419
1420 static enum print_line_t
1421 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1422                              struct trace_event *event)
1423 {
1424         return blk_trace_synthesize_old_trace(iter) ?
1425                         TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1426 }
1427
1428 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1429 {
1430         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1431                 return TRACE_TYPE_UNHANDLED;
1432
1433         return print_one_line(iter, true);
1434 }
1435
1436 static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
1437 {
1438         /* don't output context-info for blk_classic output */
1439         if (bit == TRACE_BLK_OPT_CLASSIC) {
1440                 if (set)
1441                         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1442                 else
1443                         trace_flags |= TRACE_ITER_CONTEXT_INFO;
1444         }
1445         return 0;
1446 }
1447
1448 static struct tracer blk_tracer __read_mostly = {
1449         .name           = "blk",
1450         .init           = blk_tracer_init,
1451         .reset          = blk_tracer_reset,
1452         .start          = blk_tracer_start,
1453         .stop           = blk_tracer_stop,
1454         .print_header   = blk_tracer_print_header,
1455         .print_line     = blk_tracer_print_line,
1456         .flags          = &blk_tracer_flags,
1457         .set_flag       = blk_tracer_set_flag,
1458 };
1459
1460 static struct trace_event_functions trace_blk_event_funcs = {
1461         .trace          = blk_trace_event_print,
1462         .binary         = blk_trace_event_print_binary,
1463 };
1464
1465 static struct trace_event trace_blk_event = {
1466         .type           = TRACE_BLK,
1467         .funcs          = &trace_blk_event_funcs,
1468 };
1469
1470 static int __init init_blk_tracer(void)
1471 {
1472         if (!register_ftrace_event(&trace_blk_event)) {
1473                 pr_warning("Warning: could not register block events\n");
1474                 return 1;
1475         }
1476
1477         if (register_tracer(&blk_tracer) != 0) {
1478                 pr_warning("Warning: could not register the block tracer\n");
1479                 unregister_ftrace_event(&trace_blk_event);
1480                 return 1;
1481         }
1482
1483         return 0;
1484 }
1485
1486 device_initcall(init_blk_tracer);
1487
1488 static int blk_trace_remove_queue(struct request_queue *q)
1489 {
1490         struct blk_trace *bt;
1491
1492         bt = xchg(&q->blk_trace, NULL);
1493         if (bt == NULL)
1494                 return -EINVAL;
1495
1496         if (atomic_dec_and_test(&blk_probes_ref))
1497                 blk_unregister_tracepoints();
1498
1499         blk_trace_free(bt);
1500         return 0;
1501 }
1502
1503 /*
1504  * Setup everything required to start tracing
1505  */
1506 static int blk_trace_setup_queue(struct request_queue *q,
1507                                  struct block_device *bdev)
1508 {
1509         struct blk_trace *old_bt, *bt = NULL;
1510         int ret = -ENOMEM;
1511
1512         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1513         if (!bt)
1514                 return -ENOMEM;
1515
1516         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1517         if (!bt->msg_data)
1518                 goto free_bt;
1519
1520         bt->dev = bdev->bd_dev;
1521         bt->act_mask = (u16)-1;
1522
1523         blk_trace_setup_lba(bt, bdev);
1524
1525         old_bt = xchg(&q->blk_trace, bt);
1526         if (old_bt != NULL) {
1527                 (void)xchg(&q->blk_trace, old_bt);
1528                 ret = -EBUSY;
1529                 goto free_bt;
1530         }
1531
1532         if (atomic_inc_return(&blk_probes_ref) == 1)
1533                 blk_register_tracepoints();
1534         return 0;
1535
1536 free_bt:
1537         blk_trace_free(bt);
1538         return ret;
1539 }
1540
1541 /*
1542  * sysfs interface to enable and configure tracing
1543  */
1544
1545 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1546                                          struct device_attribute *attr,
1547                                          char *buf);
1548 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1549                                           struct device_attribute *attr,
1550                                           const char *buf, size_t count);
1551 #define BLK_TRACE_DEVICE_ATTR(_name) \
1552         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1553                     sysfs_blk_trace_attr_show, \
1554                     sysfs_blk_trace_attr_store)
1555
1556 static BLK_TRACE_DEVICE_ATTR(enable);
1557 static BLK_TRACE_DEVICE_ATTR(act_mask);
1558 static BLK_TRACE_DEVICE_ATTR(pid);
1559 static BLK_TRACE_DEVICE_ATTR(start_lba);
1560 static BLK_TRACE_DEVICE_ATTR(end_lba);
1561
1562 static struct attribute *blk_trace_attrs[] = {
1563         &dev_attr_enable.attr,
1564         &dev_attr_act_mask.attr,
1565         &dev_attr_pid.attr,
1566         &dev_attr_start_lba.attr,
1567         &dev_attr_end_lba.attr,
1568         NULL
1569 };
1570
1571 struct attribute_group blk_trace_attr_group = {
1572         .name  = "trace",
1573         .attrs = blk_trace_attrs,
1574 };
1575
1576 static const struct {
1577         int mask;
1578         const char *str;
1579 } mask_maps[] = {
1580         { BLK_TC_READ,          "read"          },
1581         { BLK_TC_WRITE,         "write"         },
1582         { BLK_TC_BARRIER,       "barrier"       },
1583         { BLK_TC_SYNC,          "sync"          },
1584         { BLK_TC_QUEUE,         "queue"         },
1585         { BLK_TC_REQUEUE,       "requeue"       },
1586         { BLK_TC_ISSUE,         "issue"         },
1587         { BLK_TC_COMPLETE,      "complete"      },
1588         { BLK_TC_FS,            "fs"            },
1589         { BLK_TC_PC,            "pc"            },
1590         { BLK_TC_AHEAD,         "ahead"         },
1591         { BLK_TC_META,          "meta"          },
1592         { BLK_TC_DISCARD,       "discard"       },
1593         { BLK_TC_DRV_DATA,      "drv_data"      },
1594 };
1595
1596 static int blk_trace_str2mask(const char *str)
1597 {
1598         int i;
1599         int mask = 0;
1600         char *buf, *s, *token;
1601
1602         buf = kstrdup(str, GFP_KERNEL);
1603         if (buf == NULL)
1604                 return -ENOMEM;
1605         s = strstrip(buf);
1606
1607         while (1) {
1608                 token = strsep(&s, ",");
1609                 if (token == NULL)
1610                         break;
1611
1612                 if (*token == '\0')
1613                         continue;
1614
1615                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1616                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1617                                 mask |= mask_maps[i].mask;
1618                                 break;
1619                         }
1620                 }
1621                 if (i == ARRAY_SIZE(mask_maps)) {
1622                         mask = -EINVAL;
1623                         break;
1624                 }
1625         }
1626         kfree(buf);
1627
1628         return mask;
1629 }
1630
1631 static ssize_t blk_trace_mask2str(char *buf, int mask)
1632 {
1633         int i;
1634         char *p = buf;
1635
1636         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1637                 if (mask & mask_maps[i].mask) {
1638                         p += sprintf(p, "%s%s",
1639                                     (p == buf) ? "" : ",", mask_maps[i].str);
1640                 }
1641         }
1642         *p++ = '\n';
1643
1644         return p - buf;
1645 }
1646
1647 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1648 {
1649         if (bdev->bd_disk == NULL)
1650                 return NULL;
1651
1652         return bdev_get_queue(bdev);
1653 }
1654
1655 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1656                                          struct device_attribute *attr,
1657                                          char *buf)
1658 {
1659         struct hd_struct *p = dev_to_part(dev);
1660         struct request_queue *q;
1661         struct block_device *bdev;
1662         ssize_t ret = -ENXIO;
1663
1664         bdev = bdget(part_devt(p));
1665         if (bdev == NULL)
1666                 goto out;
1667
1668         q = blk_trace_get_queue(bdev);
1669         if (q == NULL)
1670                 goto out_bdput;
1671
1672         mutex_lock(&bdev->bd_mutex);
1673
1674         if (attr == &dev_attr_enable) {
1675                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1676                 goto out_unlock_bdev;
1677         }
1678
1679         if (q->blk_trace == NULL)
1680                 ret = sprintf(buf, "disabled\n");
1681         else if (attr == &dev_attr_act_mask)
1682                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1683         else if (attr == &dev_attr_pid)
1684                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1685         else if (attr == &dev_attr_start_lba)
1686                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1687         else if (attr == &dev_attr_end_lba)
1688                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1689
1690 out_unlock_bdev:
1691         mutex_unlock(&bdev->bd_mutex);
1692 out_bdput:
1693         bdput(bdev);
1694 out:
1695         return ret;
1696 }
1697
1698 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1699                                           struct device_attribute *attr,
1700                                           const char *buf, size_t count)
1701 {
1702         struct block_device *bdev;
1703         struct request_queue *q;
1704         struct hd_struct *p;
1705         u64 value;
1706         ssize_t ret = -EINVAL;
1707
1708         if (count == 0)
1709                 goto out;
1710
1711         if (attr == &dev_attr_act_mask) {
1712                 if (sscanf(buf, "%llx", &value) != 1) {
1713                         /* Assume it is a list of trace category names */
1714                         ret = blk_trace_str2mask(buf);
1715                         if (ret < 0)
1716                                 goto out;
1717                         value = ret;
1718                 }
1719         } else if (sscanf(buf, "%llu", &value) != 1)
1720                 goto out;
1721
1722         ret = -ENXIO;
1723
1724         p = dev_to_part(dev);
1725         bdev = bdget(part_devt(p));
1726         if (bdev == NULL)
1727                 goto out;
1728
1729         q = blk_trace_get_queue(bdev);
1730         if (q == NULL)
1731                 goto out_bdput;
1732
1733         mutex_lock(&bdev->bd_mutex);
1734
1735         if (attr == &dev_attr_enable) {
1736                 if (value)
1737                         ret = blk_trace_setup_queue(q, bdev);
1738                 else
1739                         ret = blk_trace_remove_queue(q);
1740                 goto out_unlock_bdev;
1741         }
1742
1743         ret = 0;
1744         if (q->blk_trace == NULL)
1745                 ret = blk_trace_setup_queue(q, bdev);
1746
1747         if (ret == 0) {
1748                 if (attr == &dev_attr_act_mask)
1749                         q->blk_trace->act_mask = value;
1750                 else if (attr == &dev_attr_pid)
1751                         q->blk_trace->pid = value;
1752                 else if (attr == &dev_attr_start_lba)
1753                         q->blk_trace->start_lba = value;
1754                 else if (attr == &dev_attr_end_lba)
1755                         q->blk_trace->end_lba = value;
1756         }
1757
1758 out_unlock_bdev:
1759         mutex_unlock(&bdev->bd_mutex);
1760 out_bdput:
1761         bdput(bdev);
1762 out:
1763         return ret ? ret : count;
1764 }
1765
1766 int blk_trace_init_sysfs(struct device *dev)
1767 {
1768         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1769 }
1770
1771 void blk_trace_remove_sysfs(struct device *dev)
1772 {
1773         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1774 }
1775
1776 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1777
1778 #ifdef CONFIG_EVENT_TRACING
1779
1780 void blk_dump_cmd(char *buf, struct request *rq)
1781 {
1782         int i, end;
1783         int len = rq->cmd_len;
1784         unsigned char *cmd = rq->cmd;
1785
1786         if (rq->cmd_type != REQ_TYPE_BLOCK_PC) {
1787                 buf[0] = '\0';
1788                 return;
1789         }
1790
1791         for (end = len - 1; end >= 0; end--)
1792                 if (cmd[end])
1793                         break;
1794         end++;
1795
1796         for (i = 0; i < len; i++) {
1797                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1798                 if (i == end && end != len - 1) {
1799                         sprintf(buf, " ..");
1800                         break;
1801                 }
1802         }
1803 }
1804
1805 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1806 {
1807         int i = 0;
1808
1809         if (rw & WRITE)
1810                 rwbs[i++] = 'W';
1811         else if (rw & REQ_DISCARD)
1812                 rwbs[i++] = 'D';
1813         else if (bytes)
1814                 rwbs[i++] = 'R';
1815         else
1816                 rwbs[i++] = 'N';
1817
1818         if (rw & REQ_RAHEAD)
1819                 rwbs[i++] = 'A';
1820         if (rw & REQ_SYNC)
1821                 rwbs[i++] = 'S';
1822         if (rw & REQ_META)
1823                 rwbs[i++] = 'M';
1824         if (rw & REQ_SECURE)
1825                 rwbs[i++] = 'E';
1826
1827         rwbs[i] = '\0';
1828 }
1829
1830 void blk_fill_rwbs_rq(char *rwbs, struct request *rq)
1831 {
1832         int rw = rq->cmd_flags & 0x03;
1833         int bytes;
1834
1835         if (rq->cmd_flags & REQ_DISCARD)
1836                 rw |= REQ_DISCARD;
1837
1838         if (rq->cmd_flags & REQ_SECURE)
1839                 rw |= REQ_SECURE;
1840
1841         bytes = blk_rq_bytes(rq);
1842
1843         blk_fill_rwbs(rwbs, rw, bytes);
1844 }
1845
1846 #endif /* CONFIG_EVENT_TRACING */
1847