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, i;
 443
 444         if (!buts->buf_size || !buts->buf_nr)
 445                 return -EINVAL;
 446
 447         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 448         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 449
 450         /*
 451          * some device names have larger paths - convert the slashes
 452          * to underscores for this to work as expected
 453          */
 454         for (i = 0; i < strlen(buts->name); i++)
 455                 if (buts->name[i] == '/')
 456                         buts->name[i] = '_';
 457
 458         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 459         if (!bt)
 460                 return -ENOMEM;
 461
 462         ret = -ENOMEM;
 463         bt->sequence = alloc_percpu(unsigned long);
 464         if (!bt->sequence)
 465                 goto err;
 466
 467         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 468         if (!bt->msg_data)
 469                 goto err;
 470
 471         ret = -ENOENT;
 472
 473         mutex_lock(&blk_tree_mutex);
 474         if (!blk_tree_root) {
 475                 blk_tree_root = debugfs_create_dir("block", NULL);
 476                 if (!blk_tree_root) {
 477                         mutex_unlock(&blk_tree_mutex);
 478                         goto err;
 479                 }
 480         }
 481         mutex_unlock(&blk_tree_mutex);
 482
 483         dir = debugfs_create_dir(buts->name, blk_tree_root);
 484
 485         if (!dir)
 486                 goto err;
 487
 488         bt->dir = dir;
 489         bt->dev = dev;
 490         atomic_set(&bt->dropped, 0);
 491         INIT_LIST_HEAD(&bt->running_list);
 492
 493         ret = -EIO;
 494         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 495                                                &blk_dropped_fops);
 496         if (!bt->dropped_file)
 497                 goto err;
 498
 499         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 500         if (!bt->msg_file)
 501                 goto err;
 502
 503         bt->rchan = relay_open("trace", dir, buts->buf_size,
 504                                 buts->buf_nr, &blk_relay_callbacks, bt);
 505         if (!bt->rchan)
 506                 goto err;
 507
 508         bt->act_mask = buts->act_mask;
 509         if (!bt->act_mask)
 510                 bt->act_mask = (u16) -1;
 511
 512         blk_trace_setup_lba(bt, bdev);
 513
 514         /* overwrite with user settings */
 515         if (buts->start_lba)
 516                 bt->start_lba = buts->start_lba;
 517         if (buts->end_lba)
 518                 bt->end_lba = buts->end_lba;
 519
 520         bt->pid = buts->pid;
 521         bt->trace_state = Blktrace_setup;
 522
 523         ret = -EBUSY;
 524         old_bt = xchg(&q->blk_trace, bt);
 525         if (old_bt) {
 526                 (void) xchg(&q->blk_trace, old_bt);
 527                 goto err;
 528         }
 529
 530         if (atomic_inc_return(&blk_probes_ref) == 1)
 531                 blk_register_tracepoints();
 532
 533         return 0;
 534 err:
 535         blk_trace_free(bt);
 536         return ret;
 537 }
 538
 539 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 540                     struct block_device *bdev,
 541                     char __user *arg)
 542 {
 543         struct blk_user_trace_setup buts;
 544         int ret;
 545
 546         ret = copy_from_user(&buts, arg, sizeof(buts));
 547         if (ret)
 548                 return -EFAULT;
 549
 550         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 551         if (ret)
 552                 return ret;
 553
 554         if (copy_to_user(arg, &buts, sizeof(buts))) {
 555                 blk_trace_remove(q);
 556                 return -EFAULT;
 557         }
 558         return 0;
 559 }
 560 EXPORT_SYMBOL_GPL(blk_trace_setup);
 561
 562 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 563 static int compat_blk_trace_setup(struct request_queue *q, char *name,
 564                                   dev_t dev, struct block_device *bdev,
 565                                   char __user *arg)
 566 {
 567         struct blk_user_trace_setup buts;
 568         struct compat_blk_user_trace_setup cbuts;
 569         int ret;
 570
 571         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
 572                 return -EFAULT;
 573
 574         buts = (struct blk_user_trace_setup) {
 575                 .act_mask = cbuts.act_mask,
 576                 .buf_size = cbuts.buf_size,
 577                 .buf_nr = cbuts.buf_nr,
 578                 .start_lba = cbuts.start_lba,
 579                 .end_lba = cbuts.end_lba,
 580                 .pid = cbuts.pid,
 581         };
 582
 583         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 584         if (ret)
 585                 return ret;
 586
 587         if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
 588                 blk_trace_remove(q);
 589                 return -EFAULT;
 590         }
 591
 592         return 0;
 593 }
 594 #endif
 595
 596 int blk_trace_startstop(struct request_queue *q, int start)
 597 {
 598         int ret;
 599         struct blk_trace *bt = q->blk_trace;
 600
 601         if (bt == NULL)
 602                 return -EINVAL;
 603
 604         /*
 605          * For starting a trace, we can transition from a setup or stopped
 606          * trace. For stopping a trace, the state must be running
 607          */
 608         ret = -EINVAL;
 609         if (start) {
 610                 if (bt->trace_state == Blktrace_setup ||
 611                     bt->trace_state == Blktrace_stopped) {
 612                         blktrace_seq++;
 613                         smp_mb();
 614                         bt->trace_state = Blktrace_running;
 615                         spin_lock_irq(&running_trace_lock);
 616                         list_add(&bt->running_list, &running_trace_list);
 617                         spin_unlock_irq(&running_trace_lock);
 618
 619                         trace_note_time(bt);
 620                         ret = 0;
 621                 }
 622         } else {
 623                 if (bt->trace_state == Blktrace_running) {
 624                         bt->trace_state = Blktrace_stopped;
 625                         spin_lock_irq(&running_trace_lock);
 626                         list_del_init(&bt->running_list);
 627                         spin_unlock_irq(&running_trace_lock);
 628                         relay_flush(bt->rchan);
 629                         ret = 0;
 630                 }
 631         }
 632
 633         return ret;
 634 }
 635 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 636
 637 /**
 638  * blk_trace_ioctl: - handle the ioctls associated with tracing
 639  * @bdev:       the block device
 640  * @cmd:        the ioctl cmd
 641  * @arg:        the argument data, if any
 642  *
 643  **/
 644 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 645 {
 646         struct request_queue *q;
 647         int ret, start = 0;
 648         char b[BDEVNAME_SIZE];
 649
 650         q = bdev_get_queue(bdev);
 651         if (!q)
 652                 return -ENXIO;
 653
 654         mutex_lock(&bdev->bd_mutex);
 655
 656         switch (cmd) {
 657         case BLKTRACESETUP:
 658                 bdevname(bdev, b);
 659                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 660                 break;
 661 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 662         case BLKTRACESETUP32:
 663                 bdevname(bdev, b);
 664                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 665                 break;
 666 #endif
 667         case BLKTRACESTART:
 668                 start = 1;
 669         case BLKTRACESTOP:
 670                 ret = blk_trace_startstop(q, start);
 671                 break;
 672         case BLKTRACETEARDOWN:
 673                 ret = blk_trace_remove(q);
 674                 break;
 675         default:
 676                 ret = -ENOTTY;
 677                 break;
 678         }
 679
 680         mutex_unlock(&bdev->bd_mutex);
 681         return ret;
 682 }
 683
 684 /**
 685  * blk_trace_shutdown: - stop and cleanup trace structures
 686  * @q:    the request queue associated with the device
 687  *
 688  **/
 689 void blk_trace_shutdown(struct request_queue *q)
 690 {
 691         if (q->blk_trace) {
 692                 blk_trace_startstop(q, 0);
 693                 blk_trace_remove(q);
 694         }
 695 }
 696
 697 /*
 698  * blktrace probes
 699  */
 700
 701 /**
 702  * blk_add_trace_rq - Add a trace for a request oriented action
 703  * @q:          queue the io is for
 704  * @rq:         the source request
 705  * @what:       the action
 706  *
 707  * Description:
 708  *     Records an action against a request. Will log the bio offset + size.
 709  *
 710  **/
 711 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 712                              u32 what)
 713 {
 714         struct blk_trace *bt = q->blk_trace;
 715
 716         if (likely(!bt))
 717                 return;
 718
 719         if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
 720                 what |= BLK_TC_ACT(BLK_TC_PC);
 721                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), rq->cmd_flags,
 722                                 what, rq->errors, rq->cmd_len, rq->cmd);
 723         } else  {
 724                 what |= BLK_TC_ACT(BLK_TC_FS);
 725                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 726                                 rq->cmd_flags, what, rq->errors, 0, NULL);
 727         }
 728 }
 729
 730 static void blk_add_trace_rq_abort(void *ignore,
 731                                    struct request_queue *q, struct request *rq)
 732 {
 733         blk_add_trace_rq(q, rq, BLK_TA_ABORT);
 734 }
 735
 736 static void blk_add_trace_rq_insert(void *ignore,
 737                                     struct request_queue *q, struct request *rq)
 738 {
 739         blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 740 }
 741
 742 static void blk_add_trace_rq_issue(void *ignore,
 743                                    struct request_queue *q, struct request *rq)
 744 {
 745         blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
 746 }
 747
 748 static void blk_add_trace_rq_requeue(void *ignore,
 749                                      struct request_queue *q,
 750                                      struct request *rq)
 751 {
 752         blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
 753 }
 754
 755 static void blk_add_trace_rq_complete(void *ignore,
 756                                       struct request_queue *q,
 757                                       struct request *rq)
 758 {
 759         blk_add_trace_rq(q, rq, 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         if (!error && !bio_flagged(bio, BIO_UPTODATE))
 782                 error = EIO;
 783
 784         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
 785                         error, 0, NULL);
 786 }
 787
 788 static void blk_add_trace_bio_bounce(void *ignore,
 789                                      struct request_queue *q, struct bio *bio)
 790 {
 791         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
 792 }
 793
 794 static void blk_add_trace_bio_complete(void *ignore,
 795                                        struct request_queue *q, struct bio *bio,
 796                                        int error)
 797 {
 798         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
 799 }
 800
 801 static void blk_add_trace_bio_backmerge(void *ignore,
 802                                         struct request_queue *q,
 803                                         struct request *rq,
 804                                         struct bio *bio)
 805 {
 806         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
 807 }
 808
 809 static void blk_add_trace_bio_frontmerge(void *ignore,
 810                                          struct request_queue *q,
 811                                          struct request *rq,
 812                                          struct bio *bio)
 813 {
 814         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
 815 }
 816
 817 static void blk_add_trace_bio_queue(void *ignore,
 818                                     struct request_queue *q, struct bio *bio)
 819 {
 820         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
 821 }
 822
 823 static void blk_add_trace_getrq(void *ignore,
 824                                 struct request_queue *q,
 825                                 struct bio *bio, int rw)
 826 {
 827         if (bio)
 828                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
 829         else {
 830                 struct blk_trace *bt = q->blk_trace;
 831
 832                 if (bt)
 833                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
 834         }
 835 }
 836
 837
 838 static void blk_add_trace_sleeprq(void *ignore,
 839                                   struct request_queue *q,
 840                                   struct bio *bio, int rw)
 841 {
 842         if (bio)
 843                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
 844         else {
 845                 struct blk_trace *bt = q->blk_trace;
 846
 847                 if (bt)
 848                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
 849                                         0, 0, NULL);
 850         }
 851 }
 852
 853 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 854 {
 855         struct blk_trace *bt = q->blk_trace;
 856
 857         if (bt)
 858                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
 859 }
 860
 861 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 862                                     unsigned int depth, bool explicit)
 863 {
 864         struct blk_trace *bt = q->blk_trace;
 865
 866         if (bt) {
 867                 __be64 rpdu = cpu_to_be64(depth);
 868                 u32 what;
 869
 870                 if (explicit)
 871                         what = BLK_TA_UNPLUG_IO;
 872                 else
 873                         what = BLK_TA_UNPLUG_TIMER;
 874
 875                 __blk_add_trace(bt, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu);
 876         }
 877 }
 878
 879 static void blk_add_trace_split(void *ignore,
 880                                 struct request_queue *q, struct bio *bio,
 881                                 unsigned int pdu)
 882 {
 883         struct blk_trace *bt = q->blk_trace;
 884
 885         if (bt) {
 886                 __be64 rpdu = cpu_to_be64(pdu);
 887
 888                 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 889                                 BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
 890                                 sizeof(rpdu), &rpdu);
 891         }
 892 }
 893
 894 /**
 895  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
 896  * @ignore:     trace callback data parameter (not used)
 897  * @q:          queue the io is for
 898  * @bio:        the source bio
 899  * @dev:        target device
 900  * @from:       source sector
 901  *
 902  * Description:
 903  *     Device mapper or raid target sometimes need to split a bio because
 904  *     it spans a stripe (or similar). Add a trace for that action.
 905  *
 906  **/
 907 static void blk_add_trace_bio_remap(void *ignore,
 908                                     struct request_queue *q, struct bio *bio,
 909                                     dev_t dev, sector_t from)
 910 {
 911         struct blk_trace *bt = q->blk_trace;
 912         struct blk_io_trace_remap r;
 913
 914         if (likely(!bt))
 915                 return;
 916
 917         r.device_from = cpu_to_be32(dev);
 918         r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
 919         r.sector_from = cpu_to_be64(from);
 920
 921         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 922                         BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE),
 923                         sizeof(r), &r);
 924 }
 925
 926 /**
 927  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
 928  * @ignore:     trace callback data parameter (not used)
 929  * @q:          queue the io is for
 930  * @rq:         the source request
 931  * @dev:        target device
 932  * @from:       source sector
 933  *
 934  * Description:
 935  *     Device mapper remaps request to other devices.
 936  *     Add a trace for that action.
 937  *
 938  **/
 939 static void blk_add_trace_rq_remap(void *ignore,
 940                                    struct request_queue *q,
 941                                    struct request *rq, dev_t dev,
 942                                    sector_t from)
 943 {
 944         struct blk_trace *bt = q->blk_trace;
 945         struct blk_io_trace_remap r;
 946
 947         if (likely(!bt))
 948                 return;
 949
 950         r.device_from = cpu_to_be32(dev);
 951         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
 952         r.sector_from = cpu_to_be64(from);
 953
 954         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 955                         rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
 956                         sizeof(r), &r);
 957 }
 958
 959 /**
 960  * blk_add_driver_data - Add binary message with driver-specific data
 961  * @q:          queue the io is for
 962  * @rq:         io request
 963  * @data:       driver-specific data
 964  * @len:        length of driver-specific data
 965  *
 966  * Description:
 967  *     Some drivers might want to write driver-specific data per request.
 968  *
 969  **/
 970 void blk_add_driver_data(struct request_queue *q,
 971                          struct request *rq,
 972                          void *data, size_t len)
 973 {
 974         struct blk_trace *bt = q->blk_trace;
 975
 976         if (likely(!bt))
 977                 return;
 978
 979         if (rq->cmd_type == REQ_TYPE_BLOCK_PC)
 980                 __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
 981                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 982         else
 983                 __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
 984                                 BLK_TA_DRV_DATA, rq->errors, len, data);
 985 }
 986 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 987
 988 static void blk_register_tracepoints(void)
 989 {
 990         int ret;
 991
 992         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
 993         WARN_ON(ret);
 994         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
 995         WARN_ON(ret);
 996         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
 997         WARN_ON(ret);
 998         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
 999         WARN_ON(ret);
1000         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1001         WARN_ON(ret);
1002         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1003         WARN_ON(ret);
1004         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1005         WARN_ON(ret);
1006         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1007         WARN_ON(ret);
1008         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1009         WARN_ON(ret);
1010         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1011         WARN_ON(ret);
1012         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1013         WARN_ON(ret);
1014         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1015         WARN_ON(ret);
1016         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1017         WARN_ON(ret);
1018         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1019         WARN_ON(ret);
1020         ret = register_trace_block_split(blk_add_trace_split, NULL);
1021         WARN_ON(ret);
1022         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1023         WARN_ON(ret);
1024         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1025         WARN_ON(ret);
1026 }
1027
1028 static void blk_unregister_tracepoints(void)
1029 {
1030         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1031         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1032         unregister_trace_block_split(blk_add_trace_split, NULL);
1033         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1034         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1035         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1036         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1037         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1038         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1039         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1040         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1041         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1042         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1043         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1044         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1045         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1046         unregister_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
1047
1048         tracepoint_synchronize_unregister();
1049 }
1050
1051 /*
1052  * struct blk_io_tracer formatting routines
1053  */
1054
1055 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1056 {
1057         int i = 0;
1058         int tc = t->action >> BLK_TC_SHIFT;
1059
1060         if (t->action == BLK_TN_MESSAGE) {
1061                 rwbs[i++] = 'N';
1062                 goto out;
1063         }
1064
1065         if (tc & BLK_TC_FLUSH)
1066                 rwbs[i++] = 'F';
1067
1068         if (tc & BLK_TC_DISCARD)
1069                 rwbs[i++] = 'D';
1070         else if (tc & BLK_TC_WRITE)
1071                 rwbs[i++] = 'W';
1072         else if (t->bytes)
1073                 rwbs[i++] = 'R';
1074         else
1075                 rwbs[i++] = 'N';
1076
1077         if (tc & BLK_TC_FUA)
1078                 rwbs[i++] = 'F';
1079         if (tc & BLK_TC_AHEAD)
1080                 rwbs[i++] = 'A';
1081         if (tc & BLK_TC_SYNC)
1082                 rwbs[i++] = 'S';
1083         if (tc & BLK_TC_META)
1084                 rwbs[i++] = 'M';
1085 out:
1086         rwbs[i] = '\0';
1087 }
1088
1089 static inline
1090 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1091 {
1092         return (const struct blk_io_trace *)ent;
1093 }
1094
1095 static inline const void *pdu_start(const struct trace_entry *ent)
1096 {
1097         return te_blk_io_trace(ent) + 1;
1098 }
1099
1100 static inline u32 t_action(const struct trace_entry *ent)
1101 {
1102         return te_blk_io_trace(ent)->action;
1103 }
1104
1105 static inline u32 t_bytes(const struct trace_entry *ent)
1106 {
1107         return te_blk_io_trace(ent)->bytes;
1108 }
1109
1110 static inline u32 t_sec(const struct trace_entry *ent)
1111 {
1112         return te_blk_io_trace(ent)->bytes >> 9;
1113 }
1114
1115 static inline unsigned long long t_sector(const struct trace_entry *ent)
1116 {
1117         return te_blk_io_trace(ent)->sector;
1118 }
1119
1120 static inline __u16 t_error(const struct trace_entry *ent)
1121 {
1122         return te_blk_io_trace(ent)->error;
1123 }
1124
1125 static __u64 get_pdu_int(const struct trace_entry *ent)
1126 {
1127         const __u64 *val = pdu_start(ent);
1128         return be64_to_cpu(*val);
1129 }
1130
1131 static void get_pdu_remap(const struct trace_entry *ent,
1132                           struct blk_io_trace_remap *r)
1133 {
1134         const struct blk_io_trace_remap *__r = pdu_start(ent);
1135         __u64 sector_from = __r->sector_from;
1136
1137         r->device_from = be32_to_cpu(__r->device_from);
1138         r->device_to   = be32_to_cpu(__r->device_to);
1139         r->sector_from = be64_to_cpu(sector_from);
1140 }
1141
1142 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1143
1144 static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1145 {
1146         char rwbs[RWBS_LEN];
1147         unsigned long long ts  = iter->ts;
1148         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1149         unsigned secs          = (unsigned long)ts;
1150         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1151
1152         fill_rwbs(rwbs, t);
1153
1154         return trace_seq_printf(&iter->seq,
1155                                 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1156                                 MAJOR(t->device), MINOR(t->device), iter->cpu,
1157                                 secs, nsec_rem, iter->ent->pid, act, rwbs);
1158 }
1159
1160 static int blk_log_action(struct trace_iterator *iter, const char *act)
1161 {
1162         char rwbs[RWBS_LEN];
1163         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1164
1165         fill_rwbs(rwbs, t);
1166         return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1167                                 MAJOR(t->device), MINOR(t->device), act, rwbs);
1168 }
1169
1170 static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1171 {
1172         const unsigned char *pdu_buf;
1173         int pdu_len;
1174         int i, end, ret;
1175
1176         pdu_buf = pdu_start(ent);
1177         pdu_len = te_blk_io_trace(ent)->pdu_len;
1178
1179         if (!pdu_len)
1180                 return 1;
1181
1182         /* find the last zero that needs to be printed */
1183         for (end = pdu_len - 1; end >= 0; end--)
1184                 if (pdu_buf[end])
1185                         break;
1186         end++;
1187
1188         if (!trace_seq_putc(s, '('))
1189                 return 0;
1190
1191         for (i = 0; i < pdu_len; i++) {
1192
1193                 ret = trace_seq_printf(s, "%s%02x",
1194                                        i == 0 ? "" : " ", pdu_buf[i]);
1195                 if (!ret)
1196                         return ret;
1197
1198                 /*
1199                  * stop when the rest is just zeroes and indicate so
1200                  * with a ".." appended
1201                  */
1202                 if (i == end && end != pdu_len - 1)
1203                         return trace_seq_puts(s, " ..) ");
1204         }
1205
1206         return trace_seq_puts(s, ") ");
1207 }
1208
1209 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1210 {
1211         char cmd[TASK_COMM_LEN];
1212
1213         trace_find_cmdline(ent->pid, cmd);
1214
1215         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1216                 int ret;
1217
1218                 ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1219                 if (!ret)
1220                         return 0;
1221                 ret = blk_log_dump_pdu(s, ent);
1222                 if (!ret)
1223                         return 0;
1224                 return trace_seq_printf(s, "[%s]\n", cmd);
1225         } else {
1226                 if (t_sec(ent))
1227                         return trace_seq_printf(s, "%llu + %u [%s]\n",
1228                                                 t_sector(ent), t_sec(ent), cmd);
1229                 return trace_seq_printf(s, "[%s]\n", cmd);
1230         }
1231 }
1232
1233 static int blk_log_with_error(struct trace_seq *s,
1234                               const struct trace_entry *ent)
1235 {
1236         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1237                 int ret;
1238
1239                 ret = blk_log_dump_pdu(s, ent);
1240                 if (ret)
1241                         return trace_seq_printf(s, "[%d]\n", t_error(ent));
1242                 return 0;
1243         } else {
1244                 if (t_sec(ent))
1245                         return trace_seq_printf(s, "%llu + %u [%d]\n",
1246                                                 t_sector(ent),
1247                                                 t_sec(ent), t_error(ent));
1248                 return trace_seq_printf(s, "%llu [%d]\n",
1249                                         t_sector(ent), t_error(ent));
1250         }
1251 }
1252
1253 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1254 {
1255         struct blk_io_trace_remap r = { .device_from = 0, };
1256
1257         get_pdu_remap(ent, &r);
1258         return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1259                                 t_sector(ent), t_sec(ent),
1260                                 MAJOR(r.device_from), MINOR(r.device_from),
1261                                 (unsigned long long)r.sector_from);
1262 }
1263
1264 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1265 {
1266         char cmd[TASK_COMM_LEN];
1267
1268         trace_find_cmdline(ent->pid, cmd);
1269
1270         return trace_seq_printf(s, "[%s]\n", cmd);
1271 }
1272
1273 static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1274 {
1275         char cmd[TASK_COMM_LEN];
1276
1277         trace_find_cmdline(ent->pid, cmd);
1278
1279         return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1280 }
1281
1282 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1283 {
1284         char cmd[TASK_COMM_LEN];
1285
1286         trace_find_cmdline(ent->pid, cmd);
1287
1288         return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1289                                 get_pdu_int(ent), cmd);
1290 }
1291
1292 static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1293 {
1294         int ret;
1295         const struct blk_io_trace *t = te_blk_io_trace(ent);
1296
1297         ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1298         if (ret)
1299                 return trace_seq_putc(s, '\n');
1300         return ret;
1301 }
1302
1303 /*
1304  * struct tracer operations
1305  */
1306
1307 static void blk_tracer_print_header(struct seq_file *m)
1308 {
1309         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1310                 return;
1311         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1312                     "#  |     |     |           |   |   |\n");
1313 }
1314
1315 static void blk_tracer_start(struct trace_array *tr)
1316 {
1317         blk_tracer_enabled = true;
1318 }
1319
1320 static int blk_tracer_init(struct trace_array *tr)
1321 {
1322         blk_tr = tr;
1323         blk_tracer_start(tr);
1324         return 0;
1325 }
1326
1327 static void blk_tracer_stop(struct trace_array *tr)
1328 {
1329         blk_tracer_enabled = false;
1330 }
1331
1332 static void blk_tracer_reset(struct trace_array *tr)
1333 {
1334         blk_tracer_stop(tr);
1335 }
1336
1337 static const struct {
1338         const char *act[2];
1339         int        (*print)(struct trace_seq *s, const struct trace_entry *ent);
1340 } what2act[] = {
1341         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1342         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1343         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1344         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1345         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1346         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1347         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1348         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1349         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1350         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1351         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1352         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1353         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1354         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1355         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1356 };
1357
1358 static enum print_line_t print_one_line(struct trace_iterator *iter,
1359                                         bool classic)
1360 {
1361         struct trace_seq *s = &iter->seq;
1362         const struct blk_io_trace *t;
1363         u16 what;
1364         int ret;
1365         bool long_act;
1366         blk_log_action_t *log_action;
1367
1368         t          = te_blk_io_trace(iter->ent);
1369         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1370         long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1371         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1372
1373         if (t->action == BLK_TN_MESSAGE) {
1374                 ret = log_action(iter, long_act ? "message" : "m");
1375                 if (ret)
1376                         ret = blk_log_msg(s, iter->ent);
1377                 goto out;
1378         }
1379
1380         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1381                 ret = trace_seq_printf(s, "Unknown action %x\n", what);
1382         else {
1383                 ret = log_action(iter, what2act[what].act[long_act]);
1384                 if (ret)
1385                         ret = what2act[what].print(s, iter->ent);
1386         }
1387 out:
1388         return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1389 }
1390
1391 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1392                                                int flags, struct trace_event *event)
1393 {
1394         return print_one_line(iter, false);
1395 }
1396
1397 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1398 {
1399         struct trace_seq *s = &iter->seq;
1400         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1401         const int offset = offsetof(struct blk_io_trace, sector);
1402         struct blk_io_trace old = {
1403                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1404                 .time     = iter->ts,
1405         };
1406
1407         if (!trace_seq_putmem(s, &old, offset))
1408                 return 0;
1409         return trace_seq_putmem(s, &t->sector,
1410                                 sizeof(old) - offset + t->pdu_len);
1411 }
1412
1413 static enum print_line_t
1414 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1415                              struct trace_event *event)
1416 {
1417         return blk_trace_synthesize_old_trace(iter) ?
1418                         TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1419 }
1420
1421 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1422 {
1423         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1424                 return TRACE_TYPE_UNHANDLED;
1425
1426         return print_one_line(iter, true);
1427 }
1428
1429 static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
1430 {
1431         /* don't output context-info for blk_classic output */
1432         if (bit == TRACE_BLK_OPT_CLASSIC) {
1433                 if (set)
1434                         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1435                 else
1436                         trace_flags |= TRACE_ITER_CONTEXT_INFO;
1437         }
1438         return 0;
1439 }
1440
1441 static struct tracer blk_tracer __read_mostly = {
1442         .name           = "blk",
1443         .init           = blk_tracer_init,
1444         .reset          = blk_tracer_reset,
1445         .start          = blk_tracer_start,
1446         .stop           = blk_tracer_stop,
1447         .print_header   = blk_tracer_print_header,
1448         .print_line     = blk_tracer_print_line,
1449         .flags          = &blk_tracer_flags,
1450         .set_flag       = blk_tracer_set_flag,
1451 };
1452
1453 static struct trace_event_functions trace_blk_event_funcs = {
1454         .trace          = blk_trace_event_print,
1455         .binary         = blk_trace_event_print_binary,
1456 };
1457
1458 static struct trace_event trace_blk_event = {
1459         .type           = TRACE_BLK,
1460         .funcs          = &trace_blk_event_funcs,
1461 };
1462
1463 static int __init init_blk_tracer(void)
1464 {
1465         if (!register_ftrace_event(&trace_blk_event)) {
1466                 pr_warning("Warning: could not register block events\n");
1467                 return 1;
1468         }
1469
1470         if (register_tracer(&blk_tracer) != 0) {
1471                 pr_warning("Warning: could not register the block tracer\n");
1472                 unregister_ftrace_event(&trace_blk_event);
1473                 return 1;
1474         }
1475
1476         return 0;
1477 }
1478
1479 device_initcall(init_blk_tracer);
1480
1481 static int blk_trace_remove_queue(struct request_queue *q)
1482 {
1483         struct blk_trace *bt;
1484
1485         bt = xchg(&q->blk_trace, NULL);
1486         if (bt == NULL)
1487                 return -EINVAL;
1488
1489         if (atomic_dec_and_test(&blk_probes_ref))
1490                 blk_unregister_tracepoints();
1491
1492         spin_lock_irq(&running_trace_lock);
1493         list_del(&bt->running_list);
1494         spin_unlock_irq(&running_trace_lock);
1495         blk_trace_free(bt);
1496         return 0;
1497 }
1498
1499 /*
1500  * Setup everything required to start tracing
1501  */
1502 static int blk_trace_setup_queue(struct request_queue *q,
1503                                  struct block_device *bdev)
1504 {
1505         struct blk_trace *old_bt, *bt = NULL;
1506         int ret = -ENOMEM;
1507
1508         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1509         if (!bt)
1510                 return -ENOMEM;
1511
1512         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1513         if (!bt->msg_data)
1514                 goto free_bt;
1515
1516         bt->dev = bdev->bd_dev;
1517         bt->act_mask = (u16)-1;
1518
1519         blk_trace_setup_lba(bt, bdev);
1520
1521         old_bt = xchg(&q->blk_trace, bt);
1522         if (old_bt != NULL) {
1523                 (void)xchg(&q->blk_trace, old_bt);
1524                 ret = -EBUSY;
1525                 goto free_bt;
1526         }
1527
1528         if (atomic_inc_return(&blk_probes_ref) == 1)
1529                 blk_register_tracepoints();
1530         return 0;
1531
1532 free_bt:
1533         blk_trace_free(bt);
1534         return ret;
1535 }
1536
1537 /*
1538  * sysfs interface to enable and configure tracing
1539  */
1540
1541 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1542                                          struct device_attribute *attr,
1543                                          char *buf);
1544 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1545                                           struct device_attribute *attr,
1546                                           const char *buf, size_t count);
1547 #define BLK_TRACE_DEVICE_ATTR(_name) \
1548         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1549                     sysfs_blk_trace_attr_show, \
1550                     sysfs_blk_trace_attr_store)
1551
1552 static BLK_TRACE_DEVICE_ATTR(enable);
1553 static BLK_TRACE_DEVICE_ATTR(act_mask);
1554 static BLK_TRACE_DEVICE_ATTR(pid);
1555 static BLK_TRACE_DEVICE_ATTR(start_lba);
1556 static BLK_TRACE_DEVICE_ATTR(end_lba);
1557
1558 static struct attribute *blk_trace_attrs[] = {
1559         &dev_attr_enable.attr,
1560         &dev_attr_act_mask.attr,
1561         &dev_attr_pid.attr,
1562         &dev_attr_start_lba.attr,
1563         &dev_attr_end_lba.attr,
1564         NULL
1565 };
1566
1567 struct attribute_group blk_trace_attr_group = {
1568         .name  = "trace",
1569         .attrs = blk_trace_attrs,
1570 };
1571
1572 static const struct {
1573         int mask;
1574         const char *str;
1575 } mask_maps[] = {
1576         { BLK_TC_READ,          "read"          },
1577         { BLK_TC_WRITE,         "write"         },
1578         { BLK_TC_FLUSH,         "flush"         },
1579         { BLK_TC_SYNC,          "sync"          },
1580         { BLK_TC_QUEUE,         "queue"         },
1581         { BLK_TC_REQUEUE,       "requeue"       },
1582         { BLK_TC_ISSUE,         "issue"         },
1583         { BLK_TC_COMPLETE,      "complete"      },
1584         { BLK_TC_FS,            "fs"            },
1585         { BLK_TC_PC,            "pc"            },
1586         { BLK_TC_AHEAD,         "ahead"         },
1587         { BLK_TC_META,          "meta"          },
1588         { BLK_TC_DISCARD,       "discard"       },
1589         { BLK_TC_DRV_DATA,      "drv_data"      },
1590         { BLK_TC_FUA,           "fua"           },
1591 };
1592
1593 static int blk_trace_str2mask(const char *str)
1594 {
1595         int i;
1596         int mask = 0;
1597         char *buf, *s, *token;
1598
1599         buf = kstrdup(str, GFP_KERNEL);
1600         if (buf == NULL)
1601                 return -ENOMEM;
1602         s = strstrip(buf);
1603
1604         while (1) {
1605                 token = strsep(&s, ",");
1606                 if (token == NULL)
1607                         break;
1608
1609                 if (*token == '\0')
1610                         continue;
1611
1612                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1613                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1614                                 mask |= mask_maps[i].mask;
1615                                 break;
1616                         }
1617                 }
1618                 if (i == ARRAY_SIZE(mask_maps)) {
1619                         mask = -EINVAL;
1620                         break;
1621                 }
1622         }
1623         kfree(buf);
1624
1625         return mask;
1626 }
1627
1628 static ssize_t blk_trace_mask2str(char *buf, int mask)
1629 {
1630         int i;
1631         char *p = buf;
1632
1633         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1634                 if (mask & mask_maps[i].mask) {
1635                         p += sprintf(p, "%s%s",
1636                                     (p == buf) ? "" : ",", mask_maps[i].str);
1637                 }
1638         }
1639         *p++ = '\n';
1640
1641         return p - buf;
1642 }
1643
1644 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1645 {
1646         if (bdev->bd_disk == NULL)
1647                 return NULL;
1648
1649         return bdev_get_queue(bdev);
1650 }
1651
1652 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1653                                          struct device_attribute *attr,
1654                                          char *buf)
1655 {
1656         struct hd_struct *p = dev_to_part(dev);
1657         struct request_queue *q;
1658         struct block_device *bdev;
1659         ssize_t ret = -ENXIO;
1660
1661         bdev = bdget(part_devt(p));
1662         if (bdev == NULL)
1663                 goto out;
1664
1665         q = blk_trace_get_queue(bdev);
1666         if (q == NULL)
1667                 goto out_bdput;
1668
1669         mutex_lock(&bdev->bd_mutex);
1670
1671         if (attr == &dev_attr_enable) {
1672                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1673                 goto out_unlock_bdev;
1674         }
1675
1676         if (q->blk_trace == NULL)
1677                 ret = sprintf(buf, "disabled\n");
1678         else if (attr == &dev_attr_act_mask)
1679                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1680         else if (attr == &dev_attr_pid)
1681                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1682         else if (attr == &dev_attr_start_lba)
1683                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1684         else if (attr == &dev_attr_end_lba)
1685                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1686
1687 out_unlock_bdev:
1688         mutex_unlock(&bdev->bd_mutex);
1689 out_bdput:
1690         bdput(bdev);
1691 out:
1692         return ret;
1693 }
1694
1695 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1696                                           struct device_attribute *attr,
1697                                           const char *buf, size_t count)
1698 {
1699         struct block_device *bdev;
1700         struct request_queue *q;
1701         struct hd_struct *p;
1702         u64 value;
1703         ssize_t ret = -EINVAL;
1704
1705         if (count == 0)
1706                 goto out;
1707
1708         if (attr == &dev_attr_act_mask) {
1709                 if (sscanf(buf, "%llx", &value) != 1) {
1710                         /* Assume it is a list of trace category names */
1711                         ret = blk_trace_str2mask(buf);
1712                         if (ret < 0)
1713                                 goto out;
1714                         value = ret;
1715                 }
1716         } else if (sscanf(buf, "%llu", &value) != 1)
1717                 goto out;
1718
1719         ret = -ENXIO;
1720
1721         p = dev_to_part(dev);
1722         bdev = bdget(part_devt(p));
1723         if (bdev == NULL)
1724                 goto out;
1725
1726         q = blk_trace_get_queue(bdev);
1727         if (q == NULL)
1728                 goto out_bdput;
1729
1730         mutex_lock(&bdev->bd_mutex);
1731
1732         if (attr == &dev_attr_enable) {
1733                 if (value)
1734                         ret = blk_trace_setup_queue(q, bdev);
1735                 else
1736                         ret = blk_trace_remove_queue(q);
1737                 goto out_unlock_bdev;
1738         }
1739
1740         ret = 0;
1741         if (q->blk_trace == NULL)
1742                 ret = blk_trace_setup_queue(q, bdev);
1743
1744         if (ret == 0) {
1745                 if (attr == &dev_attr_act_mask)
1746                         q->blk_trace->act_mask = value;
1747                 else if (attr == &dev_attr_pid)
1748                         q->blk_trace->pid = value;
1749                 else if (attr == &dev_attr_start_lba)
1750                         q->blk_trace->start_lba = value;
1751                 else if (attr == &dev_attr_end_lba)
1752                         q->blk_trace->end_lba = value;
1753         }
1754
1755 out_unlock_bdev:
1756         mutex_unlock(&bdev->bd_mutex);
1757 out_bdput:
1758         bdput(bdev);
1759 out:
1760         return ret ? ret : count;
1761 }
1762
1763 int blk_trace_init_sysfs(struct device *dev)
1764 {
1765         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1766 }
1767
1768 void blk_trace_remove_sysfs(struct device *dev)
1769 {
1770         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1771 }
1772
1773 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1774
1775 #ifdef CONFIG_EVENT_TRACING
1776
1777 void blk_dump_cmd(char *buf, struct request *rq)
1778 {
1779         int i, end;
1780         int len = rq->cmd_len;
1781         unsigned char *cmd = rq->cmd;
1782
1783         if (rq->cmd_type != REQ_TYPE_BLOCK_PC) {
1784                 buf[0] = '\0';
1785                 return;
1786         }
1787
1788         for (end = len - 1; end >= 0; end--)
1789                 if (cmd[end])
1790                         break;
1791         end++;
1792
1793         for (i = 0; i < len; i++) {
1794                 buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1795                 if (i == end && end != len - 1) {
1796                         sprintf(buf, " ..");
1797                         break;
1798                 }
1799         }
1800 }
1801
1802 void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1803 {
1804         int i = 0;
1805
1806         if (rw & REQ_FLUSH)
1807                 rwbs[i++] = 'F';
1808
1809         if (rw & WRITE)
1810                 rwbs[i++] = 'W';
1811         else if (rw & REQ_DISCARD)
1812                 rwbs[i++] = 'D';
1813         else if (bytes)
1814                 rwbs[i++] = 'R';
1815         else
1816                 rwbs[i++] = 'N';
1817
1818         if (rw & REQ_FUA)
1819                 rwbs[i++] = 'F';
1820         if (rw & REQ_RAHEAD)
1821                 rwbs[i++] = 'A';
1822         if (rw & REQ_SYNC)
1823                 rwbs[i++] = 'S';
1824         if (rw & REQ_META)
1825                 rwbs[i++] = 'M';
1826         if (rw & REQ_SECURE)
1827                 rwbs[i++] = 'E';
1828
1829         rwbs[i] = '\0';
1830 }
1831 EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1832
1833 #endif /* CONFIG_EVENT_TRACING */
1834