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