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(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(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 = 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 =         simple_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                                                    umode_t 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;
 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         strreplace(buts->name, '/', '_');
 455
 456         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 457         if (!bt)
 458                 return -ENOMEM;
 459
 460         ret = -ENOMEM;
 461         bt->sequence = alloc_percpu(unsigned long);
 462         if (!bt->sequence)
 463                 goto err;
 464
 465         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 466         if (!bt->msg_data)
 467                 goto err;
 468
 469         ret = -ENOENT;
 470
 471         mutex_lock(&blk_tree_mutex);
 472         if (!blk_tree_root) {
 473                 blk_tree_root = debugfs_create_dir("block", NULL);
 474                 if (!blk_tree_root) {
 475                         mutex_unlock(&blk_tree_mutex);
 476                         goto err;
 477                 }
 478         }
 479         mutex_unlock(&blk_tree_mutex);
 480
 481         dir = debugfs_create_dir(buts->name, blk_tree_root);
 482
 483         if (!dir)
 484                 goto err;
 485
 486         bt->dir = dir;
 487         bt->dev = dev;
 488         atomic_set(&bt->dropped, 0);
 489         INIT_LIST_HEAD(&bt->running_list);
 490
 491         ret = -EIO;
 492         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 493                                                &blk_dropped_fops);
 494         if (!bt->dropped_file)
 495                 goto err;
 496
 497         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 498         if (!bt->msg_file)
 499                 goto err;
 500
 501         bt->rchan = relay_open("trace", dir, buts->buf_size,
 502                                 buts->buf_nr, &blk_relay_callbacks, bt);
 503         if (!bt->rchan)
 504                 goto err;
 505
 506         bt->act_mask = buts->act_mask;
 507         if (!bt->act_mask)
 508                 bt->act_mask = (u16) -1;
 509
 510         blk_trace_setup_lba(bt, bdev);
 511
 512         /* overwrite with user settings */
 513         if (buts->start_lba)
 514                 bt->start_lba = buts->start_lba;
 515         if (buts->end_lba)
 516                 bt->end_lba = buts->end_lba;
 517
 518         bt->pid = buts->pid;
 519         bt->trace_state = Blktrace_setup;
 520
 521         ret = -EBUSY;
 522         old_bt = xchg(&q->blk_trace, bt);
 523         if (old_bt) {
 524                 (void) xchg(&q->blk_trace, old_bt);
 525                 goto err;
 526         }
 527
 528         if (atomic_inc_return(&blk_probes_ref) == 1)
 529                 blk_register_tracepoints();
 530
 531         return 0;
 532 err:
 533         blk_trace_free(bt);
 534         return ret;
 535 }
 536
 537 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 538                     struct block_device *bdev,
 539                     char __user *arg)
 540 {
 541         struct blk_user_trace_setup buts;
 542         int ret;
 543
 544         ret = copy_from_user(&buts, arg, sizeof(buts));
 545         if (ret)
 546                 return -EFAULT;
 547
 548         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 549         if (ret)
 550                 return ret;
 551
 552         if (copy_to_user(arg, &buts, sizeof(buts))) {
 553                 blk_trace_remove(q);
 554                 return -EFAULT;
 555         }
 556         return 0;
 557 }
 558 EXPORT_SYMBOL_GPL(blk_trace_setup);
 559
 560 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 561 static int compat_blk_trace_setup(struct request_queue *q, char *name,
 562                                   dev_t dev, struct block_device *bdev,
 563                                   char __user *arg)
 564 {
 565         struct blk_user_trace_setup buts;
 566         struct compat_blk_user_trace_setup cbuts;
 567         int ret;
 568
 569         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
 570                 return -EFAULT;
 571
 572         buts = (struct blk_user_trace_setup) {
 573                 .act_mask = cbuts.act_mask,
 574                 .buf_size = cbuts.buf_size,
 575                 .buf_nr = cbuts.buf_nr,
 576                 .start_lba = cbuts.start_lba,
 577                 .end_lba = cbuts.end_lba,
 578                 .pid = cbuts.pid,
 579         };
 580
 581         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 582         if (ret)
 583                 return ret;
 584
 585         if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
 586                 blk_trace_remove(q);
 587                 return -EFAULT;
 588         }
 589
 590         return 0;
 591 }
 592 #endif
 593
 594 int blk_trace_startstop(struct request_queue *q, int start)
 595 {
 596         int ret;
 597         struct blk_trace *bt = q->blk_trace;
 598
 599         if (bt == NULL)
 600                 return -EINVAL;
 601
 602         /*
 603          * For starting a trace, we can transition from a setup or stopped
 604          * trace. For stopping a trace, the state must be running
 605          */
 606         ret = -EINVAL;
 607         if (start) {
 608                 if (bt->trace_state == Blktrace_setup ||
 609                     bt->trace_state == Blktrace_stopped) {
 610                         blktrace_seq++;
 611                         smp_mb();
 612                         bt->trace_state = Blktrace_running;
 613                         spin_lock_irq(&running_trace_lock);
 614                         list_add(&bt->running_list, &running_trace_list);
 615                         spin_unlock_irq(&running_trace_lock);
 616
 617                         trace_note_time(bt);
 618                         ret = 0;
 619                 }
 620         } else {
 621                 if (bt->trace_state == Blktrace_running) {
 622                         bt->trace_state = Blktrace_stopped;
 623                         spin_lock_irq(&running_trace_lock);
 624                         list_del_init(&bt->running_list);
 625                         spin_unlock_irq(&running_trace_lock);
 626                         relay_flush(bt->rchan);
 627                         ret = 0;
 628                 }
 629         }
 630
 631         return ret;
 632 }
 633 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 634
 635 /**
 636  * blk_trace_ioctl: - handle the ioctls associated with tracing
 637  * @bdev:       the block device
 638  * @cmd:        the ioctl cmd
 639  * @arg:        the argument data, if any
 640  *
 641  **/
 642 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 643 {
 644         struct request_queue *q;
 645         int ret, start = 0;
 646         char b[BDEVNAME_SIZE];
 647
 648         q = bdev_get_queue(bdev);
 649         if (!q)
 650                 return -ENXIO;
 651
 652         mutex_lock(&bdev->bd_mutex);
 653
 654         switch (cmd) {
 655         case BLKTRACESETUP:
 656                 bdevname(bdev, b);
 657                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 658                 break;
 659 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 660         case BLKTRACESETUP32:
 661                 bdevname(bdev, b);
 662                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 663                 break;
 664 #endif
 665         case BLKTRACESTART:
 666                 start = 1;
 667         case BLKTRACESTOP:
 668                 ret = blk_trace_startstop(q, start);
 669                 break;
 670         case BLKTRACETEARDOWN:
 671                 ret = blk_trace_remove(q);
 672                 break;
 673         default:
 674                 ret = -ENOTTY;
 675                 break;
 676         }
 677
 678         mutex_unlock(&bdev->bd_mutex);
 679         return ret;
 680 }
 681
 682 /**
 683  * blk_trace_shutdown: - stop and cleanup trace structures
 684  * @q:    the request queue associated with the device
 685  *
 686  **/
 687 void blk_trace_shutdown(struct request_queue *q)
 688 {
 689         if (q->blk_trace) {
 690                 blk_trace_startstop(q, 0);
 691                 blk_trace_remove(q);
 692         }
 693 }
 694
 695 /*
 696  * blktrace probes
 697  */
 698
 699 /**
 700  * blk_add_trace_rq - Add a trace for a request oriented action
 701  * @q:          queue the io is for
 702  * @rq:         the source request
 703  * @nr_bytes:   number of completed bytes
 704  * @what:       the action
 705  *
 706  * Description:
 707  *     Records an action against a request. Will log the bio offset + size.
 708  *
 709  **/
 710 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 711                              unsigned int nr_bytes, u32 what)
 712 {
 713         struct blk_trace *bt = q->blk_trace;
 714
 715         if (likely(!bt))
 716                 return;
 717
 718         if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
 719                 what |= BLK_TC_ACT(BLK_TC_PC);
 720                 __blk_add_trace(bt, 0, nr_bytes, rq->cmd_flags,
 721                                 what, rq->errors, rq->cmd_len, rq->cmd);
 722         } else  {
 723                 what |= BLK_TC_ACT(BLK_TC_FS);
 724                 __blk_add_trace(bt, blk_rq_pos(rq), nr_bytes,
 725                                 rq->cmd_flags, what, rq->errors, 0, NULL);
 726         }
 727 }
 728
 729 static void blk_add_trace_rq_abort(void *ignore,
 730                                    struct request_queue *q, struct request *rq)
 731 {
 732         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_ABORT);
 733 }
 734
 735 static void blk_add_trace_rq_insert(void *ignore,
 736                                     struct request_queue *q, struct request *rq)
 737 {
 738         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_INSERT);
 739 }
 740
 741 static void blk_add_trace_rq_issue(void *ignore,
 742                                    struct request_queue *q, struct request *rq)
 743 {
 744         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_ISSUE);
 745 }
 746
 747 static void blk_add_trace_rq_requeue(void *ignore,
 748                                      struct request_queue *q,
 749                                      struct request *rq)
 750 {
 751         blk_add_trace_rq(q, rq, blk_rq_bytes(rq), BLK_TA_REQUEUE);
 752 }
 753
 754 static void blk_add_trace_rq_complete(void *ignore,
 755                                       struct request_queue *q,
 756                                       struct request *rq,
 757                                       unsigned int nr_bytes)
 758 {
 759         blk_add_trace_rq(q, rq, nr_bytes, BLK_TA_COMPLETE);
 760 }
 761
 762 /**
 763  * blk_add_trace_bio - Add a trace for a bio oriented action
 764  * @q:          queue the io is for
 765  * @bio:        the source bio
 766  * @what:       the action
 767  * @error:      error, if any
 768  *
 769  * Description:
 770  *     Records an action against a bio. Will log the bio offset + size.
 771  *
 772  **/
 773 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 774                               u32 what, int error)
 775 {
 776         struct blk_trace *bt = q->blk_trace;
 777
 778         if (likely(!bt))
 779                 return;
 780
 781         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
 782                         bio->bi_rw, what, error, 0, NULL);
 783 }
 784
 785 static void blk_add_trace_bio_bounce(void *ignore,
 786                                      struct request_queue *q, struct bio *bio)
 787 {
 788         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
 789 }
 790
 791 static void blk_add_trace_bio_complete(void *ignore,
 792                                        struct request_queue *q, struct bio *bio,
 793                                        int error)
 794 {
 795         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
 796 }
 797
 798 static void blk_add_trace_bio_backmerge(void *ignore,
 799                                         struct request_queue *q,
 800                                         struct request *rq,
 801                                         struct bio *bio)
 802 {
 803         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
 804 }
 805
 806 static void blk_add_trace_bio_frontmerge(void *ignore,
 807                                          struct request_queue *q,
 808                                          struct request *rq,
 809                                          struct bio *bio)
 810 {
 811         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
 812 }
 813
 814 static void blk_add_trace_bio_queue(void *ignore,
 815                                     struct request_queue *q, struct bio *bio)
 816 {
 817         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
 818 }
 819
 820 static void blk_add_trace_getrq(void *ignore,
 821                                 struct request_queue *q,
 822                                 struct bio *bio, int rw)
 823 {
 824         if (bio)
 825                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
 826         else {
 827                 struct blk_trace *bt = q->blk_trace;
 828
 829                 if (bt)
 830                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
 831         }
 832 }
 833
 834
 835 static void blk_add_trace_sleeprq(void *ignore,
 836                                   struct request_queue *q,
 837                                   struct bio *bio, int rw)
 838 {
 839         if (bio)
 840                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
 841         else {
 842                 struct blk_trace *bt = q->blk_trace;
 843
 844                 if (bt)
 845                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
 846                                         0, 0, NULL);
 847         }
 848 }
 849
 850 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 851 {
 852         struct blk_trace *bt = q->blk_trace;
 853
 854         if (bt)
 855                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
 856 }
 857
 858 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 859                                     unsigned int depth, bool explicit)
 860 {
 861         struct blk_trace *bt = q->blk_trace;
 862
 863         if (bt) {
 864                 __be64 rpdu = cpu_to_be64(depth);
 865                 u32 what;
 866
 867                 if (explicit)
 868                         what = BLK_TA_UNPLUG_IO;
 869                 else
 870                         what = BLK_TA_UNPLUG_TIMER;
 871
 872                 __blk_add_trace(bt, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu);
 873         }
 874 }
 875
 876 static void blk_add_trace_split(void *ignore,
 877                                 struct request_queue *q, struct bio *bio,
 878                                 unsigned int pdu)
 879 {
 880         struct blk_trace *bt = q->blk_trace;
 881
 882         if (bt) {
 883                 __be64 rpdu = cpu_to_be64(pdu);
 884
 885                 __blk_add_trace(bt, bio->bi_iter.bi_sector,
 886                                 bio->bi_iter.bi_size, bio->bi_rw, BLK_TA_SPLIT,
 887                                 bio->bi_error, sizeof(rpdu), &rpdu);
 888         }
 889 }
 890
 891 /**
 892  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
 893  * @ignore:     trace callback data parameter (not used)
 894  * @q:          queue the io is for
 895  * @bio:        the source bio
 896  * @dev:        target device
 897  * @from:       source sector
 898  *
 899  * Description:
 900  *     Device mapper or raid target sometimes need to split a bio because
 901  *     it spans a stripe (or similar). Add a trace for that action.
 902  *
 903  **/
 904 static void blk_add_trace_bio_remap(void *ignore,
 905                                     struct request_queue *q, struct bio *bio,
 906                                     dev_t dev, sector_t from)
 907 {
 908         struct blk_trace *bt = q->blk_trace;
 909         struct blk_io_trace_remap r;
 910
 911         if (likely(!bt))
 912                 return;
 913
 914         r.device_from = cpu_to_be32(dev);
 915         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
 916         r.sector_from = cpu_to_be64(from);
 917
 918         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
 919                         bio->bi_rw, BLK_TA_REMAP, bio->bi_error,
 920                         sizeof(r), &r);
 921 }
 922
 923 /**
 924  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
 925  * @ignore:     trace callback data parameter (not used)
 926  * @q:          queue the io is for
 927  * @rq:         the source request
 928  * @dev:        target device
 929  * @from:       source sector
 930  *
 931  * Description:
 932  *     Device mapper remaps request to other devices.
 933  *     Add a trace for that action.
 934  *
 935  **/
 936 static void blk_add_trace_rq_remap(void *ignore,
 937                                    struct request_queue *q,
 938                                    struct request *rq, dev_t dev,
 939                                    sector_t from)
 940 {
 941         struct blk_trace *bt = q->blk_trace;
 942         struct blk_io_trace_remap r;
 943
 944         if (likely(!bt))
 945                 return;
 946
 947         r.device_from = cpu_to_be32(dev);
 948         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
 949         r.sector_from = cpu_to_be64(from);
 950
 951         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 952                         rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
 953                         sizeof(r), &r);
 954 }
 955
 956 /**
 957  * blk_add_driver_data - Add binary message with driver-specific data
 958  * @q:          queue the io is for
 959  * @rq:         io request
 960  * @data:       driver-specific data
 961  * @len:        length of driver-specific data
 962  *
 963  * Description:
 964  *     Some drivers might want to write driver-specific data per request.
 965  *
 966  **/
 967 void blk_add_driver_data(struct request_queue *q,
 968                          struct request *rq,
 969                          void *data, size_t len)
 970 {
 971         struct blk_trace *bt = q->blk_trace;
 972
 973         if (likely(!bt))
 974                 return;
 975
 976         if (rq->cmd_type == REQ_TYPE_BLOCK_PC)
 977                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
 978                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 979         else
 980                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
 981                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 982 }
 983 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 984
 985 static void blk_register_tracepoints(void)
 986 {
 987         int ret;
 988
 989         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
 990         WARN_ON(ret);
 991         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
 992         WARN_ON(ret);
 993         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
 994         WARN_ON(ret);
 995         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
 996         WARN_ON(ret);
 997         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
 998         WARN_ON(ret);
 999         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1000         WARN_ON(ret);
1001         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1002         WARN_ON(ret);
1003         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1004         WARN_ON(ret);
1005         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1006         WARN_ON(ret);
1007         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1008         WARN_ON(ret);
1009         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1010         WARN_ON(ret);
1011         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1012         WARN_ON(ret);
1013         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1014         WARN_ON(ret);
1015         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1016         WARN_ON(ret);
1017         ret = register_trace_block_split(blk_add_trace_split, NULL);
1018         WARN_ON(ret);
1019         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1020         WARN_ON(ret);
1021         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1022         WARN_ON(ret);
1023 }
1024
1025 static void blk_unregister_tracepoints(void)
1026 {
1027         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1028         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1029         unregister_trace_block_split(blk_add_trace_split, NULL);
1030         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1031         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1032         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1033         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1034         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1035         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1036         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1037         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1038         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1039         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1040         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1041         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1042         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1043         unregister_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
1044
1045         tracepoint_synchronize_unregister();
1046 }
1047
1048 /*
1049  * struct blk_io_tracer formatting routines
1050  */
1051
1052 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1053 {
1054         int i = 0;
1055         int tc = t->action >> BLK_TC_SHIFT;
1056
1057         if (t->action == BLK_TN_MESSAGE) {
1058                 rwbs[i++] = 'N';
1059                 goto out;
1060         }
1061
1062         if (tc & BLK_TC_FLUSH)
1063                 rwbs[i++] = 'F';
1064
1065         if (tc & BLK_TC_DISCARD)
1066                 rwbs[i++] = 'D';
1067         else if (tc & BLK_TC_WRITE)
1068                 rwbs[i++] = 'W';
1069         else if (t->bytes)
1070                 rwbs[i++] = 'R';
1071         else
1072                 rwbs[i++] = 'N';
1073
1074         if (tc & BLK_TC_FUA)
1075                 rwbs[i++] = 'F';
1076         if (tc & BLK_TC_AHEAD)
1077                 rwbs[i++] = 'A';
1078         if (tc & BLK_TC_SYNC)
1079                 rwbs[i++] = 'S';
1080         if (tc & BLK_TC_META)
1081                 rwbs[i++] = 'M';
1082 out:
1083         rwbs[i] = '\0';
1084 }
1085
1086 static inline
1087 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1088 {
1089         return (const struct blk_io_trace *)ent;
1090 }
1091
1092 static inline const void *pdu_start(const struct trace_entry *ent)
1093 {
1094         return te_blk_io_trace(ent) + 1;
1095 }
1096
1097 static inline u32 t_action(const struct trace_entry *ent)
1098 {
1099         return te_blk_io_trace(ent)->action;
1100 }
1101
1102 static inline u32 t_bytes(const struct trace_entry *ent)
1103 {
1104         return te_blk_io_trace(ent)->bytes;
1105 }
1106
1107 static inline u32 t_sec(const struct trace_entry *ent)
1108 {
1109         return te_blk_io_trace(ent)->bytes >> 9;
1110 }
1111
1112 static inline unsigned long long t_sector(const struct trace_entry *ent)
1113 {
1114         return te_blk_io_trace(ent)->sector;
1115 }
1116
1117 static inline __u16 t_error(const struct trace_entry *ent)
1118 {
1119         return te_blk_io_trace(ent)->error;
1120 }
1121
1122 static __u64 get_pdu_int(const struct trace_entry *ent)
1123 {
1124         const __u64 *val = pdu_start(ent);
1125         return be64_to_cpu(*val);
1126 }
1127
1128 static void get_pdu_remap(const struct trace_entry *ent,
1129                           struct blk_io_trace_remap *r)
1130 {
1131         const struct blk_io_trace_remap *__r = pdu_start(ent);
1132         __u64 sector_from = __r->sector_from;
1133
1134         r->device_from = be32_to_cpu(__r->device_from);
1135         r->device_to   = be32_to_cpu(__r->device_to);
1136         r->sector_from = be64_to_cpu(sector_from);
1137 }
1138
1139 typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1140
1141 static void blk_log_action_classic(struct trace_iterator *iter, const char *act)
1142 {
1143         char rwbs[RWBS_LEN];
1144         unsigned long long ts  = iter->ts;
1145         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1146         unsigned secs          = (unsigned long)ts;
1147         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1148
1149         fill_rwbs(rwbs, t);
1150
1151         trace_seq_printf(&iter->seq,
1152                          "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1153                          MAJOR(t->device), MINOR(t->device), iter->cpu,
1154                          secs, nsec_rem, iter->ent->pid, act, rwbs);
1155 }
1156
1157 static void blk_log_action(struct trace_iterator *iter, const char *act)
1158 {
1159         char rwbs[RWBS_LEN];
1160         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1161
1162         fill_rwbs(rwbs, t);
1163         trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1164                          MAJOR(t->device), MINOR(t->device), act, rwbs);
1165 }
1166
1167 static void blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1168 {
1169         const unsigned char *pdu_buf;
1170         int pdu_len;
1171         int i, end;
1172
1173         pdu_buf = pdu_start(ent);
1174         pdu_len = te_blk_io_trace(ent)->pdu_len;
1175
1176         if (!pdu_len)
1177                 return;
1178
1179         /* find the last zero that needs to be printed */
1180         for (end = pdu_len - 1; end >= 0; end--)
1181                 if (pdu_buf[end])
1182                         break;
1183         end++;
1184
1185         trace_seq_putc(s, '(');
1186
1187         for (i = 0; i < pdu_len; i++) {
1188
1189                 trace_seq_printf(s, "%s%02x",
1190                                  i == 0 ? "" : " ", pdu_buf[i]);
1191
1192                 /*
1193                  * stop when the rest is just zeroes and indicate so
1194                  * with a ".." appended
1195                  */
1196                 if (i == end && end != pdu_len - 1) {
1197                         trace_seq_puts(s, " ..) ");
1198                         return;
1199                 }
1200         }
1201
1202         trace_seq_puts(s, ") ");
1203 }
1204
1205 static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1206 {
1207         char cmd[TASK_COMM_LEN];
1208
1209         trace_find_cmdline(ent->pid, cmd);
1210
1211         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1212                 trace_seq_printf(s, "%u ", t_bytes(ent));
1213                 blk_log_dump_pdu(s, ent);
1214                 trace_seq_printf(s, "[%s]\n", cmd);
1215         } else {
1216                 if (t_sec(ent))
1217                         trace_seq_printf(s, "%llu + %u [%s]\n",
1218                                                 t_sector(ent), t_sec(ent), cmd);
1219                 else
1220                         trace_seq_printf(s, "[%s]\n", cmd);
1221         }
1222 }
1223
1224 static void blk_log_with_error(struct trace_seq *s,
1225                               const struct trace_entry *ent)
1226 {
1227         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1228                 blk_log_dump_pdu(s, ent);
1229                 trace_seq_printf(s, "[%d]\n", t_error(ent));
1230         } else {
1231                 if (t_sec(ent))
1232                         trace_seq_printf(s, "%llu + %u [%d]\n",
1233                                          t_sector(ent),
1234                                          t_sec(ent), t_error(ent));
1235                 else
1236                         trace_seq_printf(s, "%llu [%d]\n",
1237                                          t_sector(ent), t_error(ent));
1238         }
1239 }
1240
1241 static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1242 {
1243         struct blk_io_trace_remap r = { .device_from = 0, };
1244
1245         get_pdu_remap(ent, &r);
1246         trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1247                          t_sector(ent), t_sec(ent),
1248                          MAJOR(r.device_from), MINOR(r.device_from),
1249                          (unsigned long long)r.sector_from);
1250 }
1251
1252 static void blk_log_plug(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]\n", cmd);
1259 }
1260
1261 static void blk_log_unplug(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, "[%s] %llu\n", cmd, get_pdu_int(ent));
1268 }
1269
1270 static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1271 {
1272         char cmd[TASK_COMM_LEN];
1273
1274         trace_find_cmdline(ent->pid, cmd);
1275
1276         trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1277                          get_pdu_int(ent), cmd);
1278 }
1279
1280 static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1281 {
1282         const struct blk_io_trace *t = te_blk_io_trace(ent);
1283
1284         trace_seq_putmem(s, t + 1, t->pdu_len);
1285         trace_seq_putc(s, '\n');
1286 }
1287
1288 /*
1289  * struct tracer operations
1290  */
1291
1292 static void blk_tracer_print_header(struct seq_file *m)
1293 {
1294         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1295                 return;
1296         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1297                     "#  |     |     |           |   |   |\n");
1298 }
1299
1300 static void blk_tracer_start(struct trace_array *tr)
1301 {
1302         blk_tracer_enabled = true;
1303 }
1304
1305 static int blk_tracer_init(struct trace_array *tr)
1306 {
1307         blk_tr = tr;
1308         blk_tracer_start(tr);
1309         return 0;
1310 }
1311
1312 static void blk_tracer_stop(struct trace_array *tr)
1313 {
1314         blk_tracer_enabled = false;
1315 }
1316
1317 static void blk_tracer_reset(struct trace_array *tr)
1318 {
1319         blk_tracer_stop(tr);
1320 }
1321
1322 static const struct {
1323         const char *act[2];
1324         void       (*print)(struct trace_seq *s, const struct trace_entry *ent);
1325 } what2act[] = {
1326         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1327         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1328         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1329         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1330         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1331         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1332         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1333         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1334         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1335         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1336         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1337         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1338         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1339         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1340         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1341 };
1342
1343 static enum print_line_t print_one_line(struct trace_iterator *iter,
1344                                         bool classic)
1345 {
1346         struct trace_seq *s = &iter->seq;
1347         const struct blk_io_trace *t;
1348         u16 what;
1349         bool long_act;
1350         blk_log_action_t *log_action;
1351
1352         t          = te_blk_io_trace(iter->ent);
1353         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1354         long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1355         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1356
1357         if (t->action == BLK_TN_MESSAGE) {
1358                 log_action(iter, long_act ? "message" : "m");
1359                 blk_log_msg(s, iter->ent);
1360         }
1361
1362         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1363                 trace_seq_printf(s, "Unknown action %x\n", what);
1364         else {
1365                 log_action(iter, what2act[what].act[long_act]);
1366                 what2act[what].print(s, iter->ent);
1367         }
1368
1369         return trace_handle_return(s);
1370 }
1371
1372 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1373                                                int flags, struct trace_event *event)
1374 {
1375         return print_one_line(iter, false);
1376 }
1377
1378 static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1379 {
1380         struct trace_seq *s = &iter->seq;
1381         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1382         const int offset = offsetof(struct blk_io_trace, sector);
1383         struct blk_io_trace old = {
1384                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1385                 .time     = iter->ts,
1386         };
1387
1388         trace_seq_putmem(s, &old, offset);
1389         trace_seq_putmem(s, &t->sector,
1390                          sizeof(old) - offset + t->pdu_len);
1391 }
1392
1393 static enum print_line_t
1394 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1395                              struct trace_event *event)
1396 {
1397         blk_trace_synthesize_old_trace(iter);
1398
1399         return trace_handle_return(&iter->seq);
1400 }
1401
1402 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1403 {
1404         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1405                 return TRACE_TYPE_UNHANDLED;
1406
1407         return print_one_line(iter, true);
1408 }
1409
1410 static int
1411 blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1412 {
1413         /* don't output context-info for blk_classic output */
1414         if (bit == TRACE_BLK_OPT_CLASSIC) {
1415                 if (set)
1416                         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1417                 else
1418                         trace_flags |= TRACE_ITER_CONTEXT_INFO;
1419         }
1420         return 0;
1421 }
1422
1423 static struct tracer blk_tracer __read_mostly = {
1424         .name           = "blk",
1425         .init           = blk_tracer_init,
1426         .reset          = blk_tracer_reset,
1427         .start          = blk_tracer_start,
1428         .stop           = blk_tracer_stop,
1429         .print_header   = blk_tracer_print_header,
1430         .print_line     = blk_tracer_print_line,
1431         .flags          = &blk_tracer_flags,
1432         .set_flag       = blk_tracer_set_flag,
1433 };
1434
1435 static struct trace_event_functions trace_blk_event_funcs = {
1436         .trace          = blk_trace_event_print,
1437         .binary         = blk_trace_event_print_binary,
1438 };
1439
1440 static struct trace_event trace_blk_event = {
1441         .type           = TRACE_BLK,
1442         .funcs          = &trace_blk_event_funcs,
1443 };
1444
1445 static int __init init_blk_tracer(void)
1446 {
1447         if (!register_trace_event(&trace_blk_event)) {
1448                 pr_warning("Warning: could not register block events\n");
1449                 return 1;
1450         }
1451
1452         if (register_tracer(&blk_tracer) != 0) {
1453                 pr_warning("Warning: could not register the block tracer\n");
1454                 unregister_trace_event(&trace_blk_event);
1455                 return 1;
1456         }
1457
1458         return 0;
1459 }
1460
1461 device_initcall(init_blk_tracer);
1462
1463 static int blk_trace_remove_queue(struct request_queue *q)
1464 {
1465         struct blk_trace *bt;
1466
1467         bt = xchg(&q->blk_trace, NULL);
1468         if (bt == NULL)
1469                 return -EINVAL;
1470
1471         if (atomic_dec_and_test(&blk_probes_ref))
1472                 blk_unregister_tracepoints();
1473
1474         blk_trace_free(bt);
1475         return 0;
1476 }
1477
1478 /*
1479  * Setup everything required to start tracing
1480  */
1481 static int blk_trace_setup_queue(struct request_queue *q,
1482                                  struct block_device *bdev)
1483 {
1484         struct blk_trace *old_bt, *bt = NULL;
1485         int ret = -ENOMEM;
1486
1487         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1488         if (!bt)
1489                 return -ENOMEM;
1490
1491         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1492         if (!bt->msg_data)
1493                 goto free_bt;
1494
1495         bt->dev = bdev->bd_dev;
1496         bt->act_mask = (u16)-1;
1497
1498         blk_trace_setup_lba(bt, bdev);
1499
1500         old_bt = xchg(&q->blk_trace, bt);
1501         if (old_bt != NULL) {
1502                 (void)xchg(&q->blk_trace, old_bt);
1503                 ret = -EBUSY;
1504                 goto free_bt;
1505         }
1506
1507         if (atomic_inc_return(&blk_probes_ref) == 1)
1508                 blk_register_tracepoints();
1509         return 0;
1510
1511 free_bt:
1512         blk_trace_free(bt);
1513         return ret;
1514 }
1515
1516 /*
1517  * sysfs interface to enable and configure tracing
1518  */
1519
1520 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1521                                          struct device_attribute *attr,
1522                                          char *buf);
1523 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1524                                           struct device_attribute *attr,
1525                                           const char *buf, size_t count);
1526 #define BLK_TRACE_DEVICE_ATTR(_name) \
1527         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1528                     sysfs_blk_trace_attr_show, \
1529                     sysfs_blk_trace_attr_store)
1530
1531 static BLK_TRACE_DEVICE_ATTR(enable);
1532 static BLK_TRACE_DEVICE_ATTR(act_mask);
1533 static BLK_TRACE_DEVICE_ATTR(pid);
1534 static BLK_TRACE_DEVICE_ATTR(start_lba);
1535 static BLK_TRACE_DEVICE_ATTR(end_lba);
1536
1537 static struct attribute *blk_trace_attrs[] = {
1538         &dev_attr_enable.attr,
1539         &dev_attr_act_mask.attr,
1540         &dev_attr_pid.attr,
1541         &dev_attr_start_lba.attr,
1542         &dev_attr_end_lba.attr,
1543         NULL
1544 };
1545
1546 struct attribute_group blk_trace_attr_group = {
1547         .name  = "trace",
1548         .attrs = blk_trace_attrs,
1549 };
1550
1551 static const struct {
1552         int mask;
1553         const char *str;
1554 } mask_maps[] = {
1555         { BLK_TC_READ,          "read"          },
1556         { BLK_TC_WRITE,         "write"         },
1557         { BLK_TC_FLUSH,         "flush"         },
1558         { BLK_TC_SYNC,          "sync"          },
1559         { BLK_TC_QUEUE,         "queue"         },
1560         { BLK_TC_REQUEUE,       "requeue"       },
1561         { BLK_TC_ISSUE,         "issue"         },
1562         { BLK_TC_COMPLETE,      "complete"      },
1563         { BLK_TC_FS,            "fs"            },
1564         { BLK_TC_PC,            "pc"            },
1565         { BLK_TC_AHEAD,         "ahead"         },
1566         { BLK_TC_META,          "meta"          },
1567         { BLK_TC_DISCARD,       "discard"       },
1568         { BLK_TC_DRV_DATA,      "drv_data"      },
1569         { BLK_TC_FUA,           "fua"           },
1570 };
1571
1572 static int blk_trace_str2mask(const char *str)
1573 {
1574         int i;
1575         int mask = 0;
1576         char *buf, *s, *token;
1577
1578         buf = kstrdup(str, GFP_KERNEL);
1579         if (buf == NULL)
1580                 return -ENOMEM;
1581         s = strstrip(buf);
1582
1583         while (1) {
1584                 token = strsep(&s, ",");
1585                 if (token == NULL)
1586                         break;
1587
1588                 if (*token == '\0')
1589                         continue;
1590
1591                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1592                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1593                                 mask |= mask_maps[i].mask;
1594                                 break;
1595                         }
1596                 }
1597                 if (i == ARRAY_SIZE(mask_maps)) {
1598                         mask = -EINVAL;
1599                         break;
1600                 }
1601         }
1602         kfree(buf);
1603
1604         return mask;
1605 }
1606
1607 static ssize_t blk_trace_mask2str(char *buf, int mask)
1608 {
1609         int i;
1610         char *p = buf;
1611
1612         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1613                 if (mask & mask_maps[i].mask) {
1614                         p += sprintf(p, "%s%s",
1615                                     (p == buf) ? "" : ",", mask_maps[i].str);
1616                 }
1617         }
1618         *p++ = '\n';
1619
1620         return p - buf;
1621 }
1622
1623 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1624 {
1625         if (bdev->bd_disk == NULL)
1626                 return NULL;
1627
1628         return bdev_get_queue(bdev);
1629 }
1630
1631 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1632                                          struct device_attribute *attr,
1633                                          char *buf)
1634 {
1635         struct hd_struct *p = dev_to_part(dev);
1636         struct request_queue *q;
1637         struct block_device *bdev;
1638         ssize_t ret = -ENXIO;
1639
1640         bdev = bdget(part_devt(p));
1641         if (bdev == NULL)
1642                 goto out;
1643
1644         q = blk_trace_get_queue(bdev);
1645         if (q == NULL)
1646                 goto out_bdput;
1647
1648         mutex_lock(&bdev->bd_mutex);
1649
1650         if (attr == &dev_attr_enable) {
1651                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1652                 goto out_unlock_bdev;
1653         }
1654
1655         if (q->blk_trace == NULL)
1656                 ret = sprintf(buf, "disabled\n");
1657         else if (attr == &dev_attr_act_mask)
1658                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1659         else if (attr == &dev_attr_pid)
1660                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1661         else if (attr == &dev_attr_start_lba)
1662                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1663         else if (attr == &dev_attr_end_lba)
1664                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1665
1666 out_unlock_bdev:
1667         mutex_unlock(&bdev->bd_mutex);
1668 out_bdput:
1669         bdput(bdev);
1670 out:
1671         return ret;
1672 }
1673
1674 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1675                                           struct device_attribute *attr,
1676                                           const char *buf, size_t count)
1677 {
1678         struct block_device *bdev;
1679         struct request_queue *q;
1680         struct hd_struct *p;
1681         u64 value;
1682         ssize_t ret = -EINVAL;
1683
1684         if (count == 0)
1685                 goto out;
1686
1687         if (attr == &dev_attr_act_mask) {
1688                 if (sscanf(buf, "%llx", &value) != 1) {
1689                         /* Assume it is a list of trace category names */
1690                         ret = blk_trace_str2mask(buf);
1691                         if (ret < 0)
1692                                 goto out;
1693                         value = ret;
1694                 }
1695         } else if (sscanf(buf, "%llu", &value) != 1)
1696                 goto out;
1697
1698         ret = -ENXIO;
1699
1700         p = dev_to_part(dev);
1701         bdev = bdget(part_devt(p));
1702         if (bdev == NULL)
1703                 goto out;
1704
1705         q = blk_trace_get_queue(bdev);
1706         if (q == NULL)
1707                 goto out_bdput;
1708
1709         mutex_lock(&bdev->bd_mutex);
1710
1711         if (attr == &dev_attr_enable) {
1712                 if (value)
1713                         ret = blk_trace_setup_queue(q, bdev);
1714                 else
1715                         ret = blk_trace_remove_queue(q);
1716                 goto out_unlock_bdev;
1717         }
1718
1719         ret = 0;
1720         if (q->blk_trace == NULL)
1721                 ret = blk_trace_setup_queue(q, bdev);
1722
1723         if (ret == 0) {
1724                 if (attr == &dev_attr_act_mask)
1725                         q->blk_trace->act_mask = value;
1726                 else if (attr == &dev_attr_pid)
1727                         q->blk_trace->pid = value;
1728                 else if (attr == &dev_attr_start_lba)
1729                         q->blk_trace->start_lba = value;
1730                 else if (attr == &dev_attr_end_lba)
1731                         q->blk_trace->end_lba = value;
1732         }
1733
1734 out_unlock_bdev:
1735         mutex_unlock(&bdev->bd_mutex);
1736 out_bdput:
1737         bdput(bdev);
1738 out:
1739         return ret ? ret : count;
1740 }
1741
1742 int blk_trace_init_sysfs(struct device *dev)
1743 {
1744         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1745 }
1746
1747 void blk_trace_remove_sysfs(struct device *dev)
1748 {
1749         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1750 }
1751
1752 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1753
1754 #ifdef CONFIG_EVENT_TRACING
1755
1756 void blk_dump_cmd(char *buf, struct request *rq)
1757 {
1758         int i, end;
1759         int len = rq->cmd_len;
1760         unsigned char *cmd = rq->cmd;
1761
1762         if (rq->cmd_type != REQ_TYPE_BLOCK_PC) {
1763                 buf[0] = '\0';
1764                 return;
1765         }
1766
1767         for (end = len - 1; end >= 0; end--)
1768                 if (cmd[end])
1769                         break;
1770         end++;
1771
1772         for (i = 0; i < len; i++) {
1773                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1774                 if (i == end && end != len - 1) {
1775                         sprintf(buf, " ..");
1776                         break;
1777                 }
1778         }
1779 }
1780
1781 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1782 {
1783         int i = 0;
1784
1785         if (rw & REQ_FLUSH)
1786                 rwbs[i++] = 'F';
1787
1788         if (rw & WRITE)
1789                 rwbs[i++] = 'W';
1790         else if (rw & REQ_DISCARD)
1791                 rwbs[i++] = 'D';
1792         else if (bytes)
1793                 rwbs[i++] = 'R';
1794         else
1795                 rwbs[i++] = 'N';
1796
1797         if (rw & REQ_FUA)
1798                 rwbs[i++] = 'F';
1799         if (rw & REQ_RAHEAD)
1800                 rwbs[i++] = 'A';
1801         if (rw & REQ_SYNC)
1802                 rwbs[i++] = 'S';
1803         if (rw & REQ_META)
1804                 rwbs[i++] = 'M';
1805         if (rw & REQ_SECURE)
1806                 rwbs[i++] = 'E';
1807
1808         rwbs[i] = '\0';
1809 }
1810 EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1811
1812 #endif /* CONFIG_EVENT_TRACING */
1813