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