git.oblomov.eu Git - linux-2.6/blob - 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 <trace/block.h>
  27 #include <linux/uaccess.h>
  28 #include "trace_output.h"
  29
  30 static unsigned int blktrace_seq __read_mostly = 1;
  31
  32 static struct trace_array *blk_tr;
  33 static bool blk_tracer_enabled __read_mostly;
  34
  35 /* Select an alternative, minimalistic output than the original one */
  36 #define TRACE_BLK_OPT_CLASSIC   0x1
  37
  38 static struct tracer_opt blk_tracer_opts[] = {
  39         /* Default disable the minimalistic output */
  40         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
  41         { }
  42 };
  43
  44 static struct tracer_flags blk_tracer_flags = {
  45         .val  = 0,
  46         .opts = blk_tracer_opts,
  47 };
  48
  49 /* Global reference count of probes */
  50 static atomic_t blk_probes_ref = ATOMIC_INIT(0);
  51
  52 static void blk_register_tracepoints(void);
  53 static void blk_unregister_tracepoints(void);
  54
  55 /*
  56  * Send out a notify message.
  57  */
  58 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
  59                        const void *data, size_t len)
  60 {
  61         struct blk_io_trace *t;
  62         struct ring_buffer_event *event = NULL;
  63         int pc = 0;
  64         int cpu = smp_processor_id();
  65         bool blk_tracer = blk_tracer_enabled;
  66
  67         if (blk_tracer) {
  68                 pc = preempt_count();
  69                 event = trace_buffer_lock_reserve(blk_tr, TRACE_BLK,
  70                                                   sizeof(*t) + len,
  71                                                   0, pc);
  72                 if (!event)
  73                         return;
  74                 t = ring_buffer_event_data(event);
  75                 goto record_it;
  76         }
  77
  78         if (!bt->rchan)
  79                 return;
  80
  81         t = relay_reserve(bt->rchan, sizeof(*t) + len);
  82         if (t) {
  83                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
  84                 t->time = ktime_to_ns(ktime_get());
  85 record_it:
  86                 t->device = bt->dev;
  87                 t->action = action;
  88                 t->pid = pid;
  89                 t->cpu = cpu;
  90                 t->pdu_len = len;
  91                 memcpy((void *) t + sizeof(*t), data, len);
  92
  93                 if (blk_tracer)
  94                         trace_buffer_unlock_commit(blk_tr, event, 0, pc);
  95         }
  96 }
  97
  98 /*
  99  * Send out a notify for this process, if we haven't done so since a trace
 100  * started
 101  */
 102 static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
 103 {
 104         tsk->btrace_seq = blktrace_seq;
 105         trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));
 106 }
 107
 108 static void trace_note_time(struct blk_trace *bt)
 109 {
 110         struct timespec now;
 111         unsigned long flags;
 112         u32 words[2];
 113
 114         getnstimeofday(&now);
 115         words[0] = now.tv_sec;
 116         words[1] = now.tv_nsec;
 117
 118         local_irq_save(flags);
 119         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
 120         local_irq_restore(flags);
 121 }
 122
 123 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 124 {
 125         int n;
 126         va_list args;
 127         unsigned long flags;
 128         char *buf;
 129
 130         if (unlikely(bt->trace_state != Blktrace_running &&
 131                      !blk_tracer_enabled))
 132                 return;
 133
 134         local_irq_save(flags);
 135         buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
 136         va_start(args, fmt);
 137         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 138         va_end(args);
 139
 140         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
 141         local_irq_restore(flags);
 142 }
 143 EXPORT_SYMBOL_GPL(__trace_note_message);
 144
 145 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
 146                          pid_t pid)
 147 {
 148         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
 149                 return 1;
 150         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
 151                 return 1;
 152         if (bt->pid && pid != bt->pid)
 153                 return 1;
 154
 155         return 0;
 156 }
 157
 158 /*
 159  * Data direction bit lookup
 160  */
 161 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
 162                                  BLK_TC_ACT(BLK_TC_WRITE) };
 163
 164 /* The ilog2() calls fall out because they're constant */
 165 #define MASK_TC_BIT(rw, __name) ((rw & (1 << BIO_RW_ ## __name)) << \
 166           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - BIO_RW_ ## __name))
 167
 168 /*
 169  * The worker for the various blk_add_trace*() types. Fills out a
 170  * blk_io_trace structure and places it in a per-cpu subbuffer.
 171  */
 172 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 173                      int rw, u32 what, int error, int pdu_len, void *pdu_data)
 174 {
 175         struct task_struct *tsk = current;
 176         struct ring_buffer_event *event = NULL;
 177         struct blk_io_trace *t;
 178         unsigned long flags = 0;
 179         unsigned long *sequence;
 180         pid_t pid;
 181         int cpu, pc = 0;
 182         bool blk_tracer = blk_tracer_enabled;
 183
 184         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
 185                 return;
 186
 187         what |= ddir_act[rw & WRITE];
 188         what |= MASK_TC_BIT(rw, BARRIER);
 189         what |= MASK_TC_BIT(rw, SYNCIO);
 190         what |= MASK_TC_BIT(rw, AHEAD);
 191         what |= MASK_TC_BIT(rw, META);
 192         what |= MASK_TC_BIT(rw, DISCARD);
 193
 194         pid = tsk->pid;
 195         if (act_log_check(bt, what, sector, pid))
 196                 return;
 197         cpu = raw_smp_processor_id();
 198
 199         if (blk_tracer) {
 200                 tracing_record_cmdline(current);
 201
 202                 pc = preempt_count();
 203                 event = trace_buffer_lock_reserve(blk_tr, TRACE_BLK,
 204                                                   sizeof(*t) + pdu_len,
 205                                                   0, pc);
 206                 if (!event)
 207                         return;
 208                 t = ring_buffer_event_data(event);
 209                 goto record_it;
 210         }
 211
 212         /*
 213          * A word about the locking here - we disable interrupts to reserve
 214          * some space in the relay per-cpu buffer, to prevent an irq
 215          * from coming in and stepping on our toes.
 216          */
 217         local_irq_save(flags);
 218
 219         if (unlikely(tsk->btrace_seq != blktrace_seq))
 220                 trace_note_tsk(bt, tsk);
 221
 222         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
 223         if (t) {
 224                 sequence = per_cpu_ptr(bt->sequence, cpu);
 225
 226                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 227                 t->sequence = ++(*sequence);
 228                 t->time = ktime_to_ns(ktime_get());
 229 record_it:
 230                 /*
 231                  * These two are not needed in ftrace as they are in the
 232                  * generic trace_entry, filled by tracing_generic_entry_update,
 233                  * but for the trace_event->bin() synthesizer benefit we do it
 234                  * here too.
 235                  */
 236                 t->cpu = cpu;
 237                 t->pid = pid;
 238
 239                 t->sector = sector;
 240                 t->bytes = bytes;
 241                 t->action = what;
 242                 t->device = bt->dev;
 243                 t->error = error;
 244                 t->pdu_len = pdu_len;
 245
 246                 if (pdu_len)
 247                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
 248
 249                 if (blk_tracer) {
 250                         trace_buffer_unlock_commit(blk_tr, event, 0, pc);
 251                         return;
 252                 }
 253         }
 254
 255         local_irq_restore(flags);
 256 }
 257
 258 static struct dentry *blk_tree_root;
 259 static DEFINE_MUTEX(blk_tree_mutex);
 260
 261 static void blk_trace_free(struct blk_trace *bt)
 262 {
 263         debugfs_remove(bt->msg_file);
 264         debugfs_remove(bt->dropped_file);
 265         relay_close(bt->rchan);
 266         free_percpu(bt->sequence);
 267         free_percpu(bt->msg_data);
 268         kfree(bt);
 269 }
 270
 271 static void blk_trace_cleanup(struct blk_trace *bt)
 272 {
 273         blk_trace_free(bt);
 274         if (atomic_dec_and_test(&blk_probes_ref))
 275                 blk_unregister_tracepoints();
 276 }
 277
 278 int blk_trace_remove(struct request_queue *q)
 279 {
 280         struct blk_trace *bt;
 281
 282         bt = xchg(&q->blk_trace, NULL);
 283         if (!bt)
 284                 return -EINVAL;
 285
 286         if (bt->trace_state != Blktrace_running)
 287                 blk_trace_cleanup(bt);
 288
 289         return 0;
 290 }
 291 EXPORT_SYMBOL_GPL(blk_trace_remove);
 292
 293 static int blk_dropped_open(struct inode *inode, struct file *filp)
 294 {
 295         filp->private_data = inode->i_private;
 296
 297         return 0;
 298 }
 299
 300 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
 301                                 size_t count, loff_t *ppos)
 302 {
 303         struct blk_trace *bt = filp->private_data;
 304         char buf[16];
 305
 306         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
 307
 308         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 309 }
 310
 311 static const struct file_operations blk_dropped_fops = {
 312         .owner =        THIS_MODULE,
 313         .open =         blk_dropped_open,
 314         .read =         blk_dropped_read,
 315 };
 316
 317 static int blk_msg_open(struct inode *inode, struct file *filp)
 318 {
 319         filp->private_data = inode->i_private;
 320
 321         return 0;
 322 }
 323
 324 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 325                                 size_t count, loff_t *ppos)
 326 {
 327         char *msg;
 328         struct blk_trace *bt;
 329
 330         if (count >= BLK_TN_MAX_MSG)
 331                 return -EINVAL;
 332
 333         msg = kmalloc(count + 1, GFP_KERNEL);
 334         if (msg == NULL)
 335                 return -ENOMEM;
 336
 337         if (copy_from_user(msg, buffer, count)) {
 338                 kfree(msg);
 339                 return -EFAULT;
 340         }
 341
 342         msg[count] = '\0';
 343         bt = filp->private_data;
 344         __trace_note_message(bt, "%s", msg);
 345         kfree(msg);
 346
 347         return count;
 348 }
 349
 350 static const struct file_operations blk_msg_fops = {
 351         .owner =        THIS_MODULE,
 352         .open =         blk_msg_open,
 353         .write =        blk_msg_write,
 354 };
 355
 356 /*
 357  * Keep track of how many times we encountered a full subbuffer, to aid
 358  * the user space app in telling how many lost events there were.
 359  */
 360 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
 361                                      void *prev_subbuf, size_t prev_padding)
 362 {
 363         struct blk_trace *bt;
 364
 365         if (!relay_buf_full(buf))
 366                 return 1;
 367
 368         bt = buf->chan->private_data;
 369         atomic_inc(&bt->dropped);
 370         return 0;
 371 }
 372
 373 static int blk_remove_buf_file_callback(struct dentry *dentry)
 374 {
 375         struct dentry *parent = dentry->d_parent;
 376         debugfs_remove(dentry);
 377
 378         /*
 379         * this will fail for all but the last file, but that is ok. what we
 380         * care about is the top level buts->name directory going away, when
 381         * the last trace file is gone. Then we don't have to rmdir() that
 382         * manually on trace stop, so it nicely solves the issue with
 383         * force killing of running traces.
 384         */
 385
 386         debugfs_remove(parent);
 387         return 0;
 388 }
 389
 390 static struct dentry *blk_create_buf_file_callback(const char *filename,
 391                                                    struct dentry *parent,
 392                                                    int mode,
 393                                                    struct rchan_buf *buf,
 394                                                    int *is_global)
 395 {
 396         return debugfs_create_file(filename, mode, parent, buf,
 397                                         &relay_file_operations);
 398 }
 399
 400 static struct rchan_callbacks blk_relay_callbacks = {
 401         .subbuf_start           = blk_subbuf_start_callback,
 402         .create_buf_file        = blk_create_buf_file_callback,
 403         .remove_buf_file        = blk_remove_buf_file_callback,
 404 };
 405
 406 static void blk_trace_setup_lba(struct blk_trace *bt,
 407                                 struct block_device *bdev)
 408 {
 409         struct hd_struct *part = NULL;
 410
 411         if (bdev)
 412                 part = bdev->bd_part;
 413
 414         if (part) {
 415                 bt->start_lba = part->start_sect;
 416                 bt->end_lba = part->start_sect + part->nr_sects;
 417         } else {
 418                 bt->start_lba = 0;
 419                 bt->end_lba = -1ULL;
 420         }
 421 }
 422
 423 /*
 424  * Setup everything required to start tracing
 425  */
 426 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 427                        struct block_device *bdev,
 428                        struct blk_user_trace_setup *buts)
 429 {
 430         struct blk_trace *old_bt, *bt = NULL;
 431         struct dentry *dir = NULL;
 432         int ret, i;
 433
 434         if (!buts->buf_size || !buts->buf_nr)
 435                 return -EINVAL;
 436
 437         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 438         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 439
 440         /*
 441          * some device names have larger paths - convert the slashes
 442          * to underscores for this to work as expected
 443          */
 444         for (i = 0; i < strlen(buts->name); i++)
 445                 if (buts->name[i] == '/')
 446                         buts->name[i] = '_';
 447
 448         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 449         if (!bt)
 450                 return -ENOMEM;
 451
 452         ret = -ENOMEM;
 453         bt->sequence = alloc_percpu(unsigned long);
 454         if (!bt->sequence)
 455                 goto err;
 456
 457         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 458         if (!bt->msg_data)
 459                 goto err;
 460
 461         ret = -ENOENT;
 462
 463         mutex_lock(&blk_tree_mutex);
 464         if (!blk_tree_root) {
 465                 blk_tree_root = debugfs_create_dir("block", NULL);
 466                 if (!blk_tree_root) {
 467                         mutex_unlock(&blk_tree_mutex);
 468                         goto err;
 469                 }
 470         }
 471         mutex_unlock(&blk_tree_mutex);
 472
 473         dir = debugfs_create_dir(buts->name, blk_tree_root);
 474
 475         if (!dir)
 476                 goto err;
 477
 478         bt->dir = dir;
 479         bt->dev = dev;
 480         atomic_set(&bt->dropped, 0);
 481
 482         ret = -EIO;
 483         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 484                                                &blk_dropped_fops);
 485         if (!bt->dropped_file)
 486                 goto err;
 487
 488         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 489         if (!bt->msg_file)
 490                 goto err;
 491
 492         bt->rchan = relay_open("trace", dir, buts->buf_size,
 493                                 buts->buf_nr, &blk_relay_callbacks, bt);
 494         if (!bt->rchan)
 495                 goto err;
 496
 497         bt->act_mask = buts->act_mask;
 498         if (!bt->act_mask)
 499                 bt->act_mask = (u16) -1;
 500
 501         blk_trace_setup_lba(bt, bdev);
 502
 503         /* overwrite with user settings */
 504         if (buts->start_lba)
 505                 bt->start_lba = buts->start_lba;
 506         if (buts->end_lba)
 507                 bt->end_lba = buts->end_lba;
 508
 509         bt->pid = buts->pid;
 510         bt->trace_state = Blktrace_setup;
 511
 512         ret = -EBUSY;
 513         old_bt = xchg(&q->blk_trace, bt);
 514         if (old_bt) {
 515                 (void) xchg(&q->blk_trace, old_bt);
 516                 goto err;
 517         }
 518
 519         if (atomic_inc_return(&blk_probes_ref) == 1)
 520                 blk_register_tracepoints();
 521
 522         return 0;
 523 err:
 524         blk_trace_free(bt);
 525         return ret;
 526 }
 527
 528 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 529                     struct block_device *bdev,
 530                     char __user *arg)
 531 {
 532         struct blk_user_trace_setup buts;
 533         int ret;
 534
 535         ret = copy_from_user(&buts, arg, sizeof(buts));
 536         if (ret)
 537                 return -EFAULT;
 538
 539         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 540         if (ret)
 541                 return ret;
 542
 543         if (copy_to_user(arg, &buts, sizeof(buts)))
 544                 return -EFAULT;
 545
 546         return 0;
 547 }
 548 EXPORT_SYMBOL_GPL(blk_trace_setup);
 549
 550 int blk_trace_startstop(struct request_queue *q, int start)
 551 {
 552         int ret;
 553         struct blk_trace *bt = q->blk_trace;
 554
 555         if (bt == NULL)
 556                 return -EINVAL;
 557
 558         /*
 559          * For starting a trace, we can transition from a setup or stopped
 560          * trace. For stopping a trace, the state must be running
 561          */
 562         ret = -EINVAL;
 563         if (start) {
 564                 if (bt->trace_state == Blktrace_setup ||
 565                     bt->trace_state == Blktrace_stopped) {
 566                         blktrace_seq++;
 567                         smp_mb();
 568                         bt->trace_state = Blktrace_running;
 569
 570                         trace_note_time(bt);
 571                         ret = 0;
 572                 }
 573         } else {
 574                 if (bt->trace_state == Blktrace_running) {
 575                         bt->trace_state = Blktrace_stopped;
 576                         relay_flush(bt->rchan);
 577                         ret = 0;
 578                 }
 579         }
 580
 581         return ret;
 582 }
 583 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 584
 585 /**
 586  * blk_trace_ioctl: - handle the ioctls associated with tracing
 587  * @bdev:       the block device
 588  * @cmd:        the ioctl cmd
 589  * @arg:        the argument data, if any
 590  *
 591  **/
 592 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 593 {
 594         struct request_queue *q;
 595         int ret, start = 0;
 596         char b[BDEVNAME_SIZE];
 597
 598         q = bdev_get_queue(bdev);
 599         if (!q)
 600                 return -ENXIO;
 601
 602         mutex_lock(&bdev->bd_mutex);
 603
 604         switch (cmd) {
 605         case BLKTRACESETUP:
 606                 bdevname(bdev, b);
 607                 ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 608                 break;
 609         case BLKTRACESTART:
 610                 start = 1;
 611         case BLKTRACESTOP:
 612                 ret = blk_trace_startstop(q, start);
 613                 break;
 614         case BLKTRACETEARDOWN:
 615                 ret = blk_trace_remove(q);
 616                 break;
 617         default:
 618                 ret = -ENOTTY;
 619                 break;
 620         }
 621
 622         mutex_unlock(&bdev->bd_mutex);
 623         return ret;
 624 }
 625
 626 /**
 627  * blk_trace_shutdown: - stop and cleanup trace structures
 628  * @q:    the request queue associated with the device
 629  *
 630  **/
 631 void blk_trace_shutdown(struct request_queue *q)
 632 {
 633         if (q->blk_trace) {
 634                 blk_trace_startstop(q, 0);
 635                 blk_trace_remove(q);
 636         }
 637 }
 638
 639 /*
 640  * blktrace probes
 641  */
 642
 643 /**
 644  * blk_add_trace_rq - Add a trace for a request oriented action
 645  * @q:          queue the io is for
 646  * @rq:         the source request
 647  * @what:       the action
 648  *
 649  * Description:
 650  *     Records an action against a request. Will log the bio offset + size.
 651  *
 652  **/
 653 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 654                                     u32 what)
 655 {
 656         struct blk_trace *bt = q->blk_trace;
 657         int rw = rq->cmd_flags & 0x03;
 658
 659         if (likely(!bt))
 660                 return;
 661
 662         if (blk_discard_rq(rq))
 663                 rw |= (1 << BIO_RW_DISCARD);
 664
 665         if (blk_pc_request(rq)) {
 666                 what |= BLK_TC_ACT(BLK_TC_PC);
 667                 __blk_add_trace(bt, 0, rq->data_len, rw, what, rq->errors,
 668                                 rq->cmd_len, rq->cmd);
 669         } else  {
 670                 what |= BLK_TC_ACT(BLK_TC_FS);
 671                 __blk_add_trace(bt, rq->hard_sector, rq->hard_nr_sectors << 9,
 672                                 rw, what, rq->errors, 0, NULL);
 673         }
 674 }
 675
 676 static void blk_add_trace_rq_abort(struct request_queue *q, struct request *rq)
 677 {
 678         blk_add_trace_rq(q, rq, BLK_TA_ABORT);
 679 }
 680
 681 static void blk_add_trace_rq_insert(struct request_queue *q, struct request *rq)
 682 {
 683         blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 684 }
 685
 686 static void blk_add_trace_rq_issue(struct request_queue *q, struct request *rq)
 687 {
 688         blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
 689 }
 690
 691 static void blk_add_trace_rq_requeue(struct request_queue *q,
 692                                      struct request *rq)
 693 {
 694         blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
 695 }
 696
 697 static void blk_add_trace_rq_complete(struct request_queue *q,
 698                                       struct request *rq)
 699 {
 700         blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
 701 }
 702
 703 /**
 704  * blk_add_trace_bio - Add a trace for a bio oriented action
 705  * @q:          queue the io is for
 706  * @bio:        the source bio
 707  * @what:       the action
 708  *
 709  * Description:
 710  *     Records an action against a bio. Will log the bio offset + size.
 711  *
 712  **/
 713 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 714                                      u32 what)
 715 {
 716         struct blk_trace *bt = q->blk_trace;
 717
 718         if (likely(!bt))
 719                 return;
 720
 721         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
 722                         !bio_flagged(bio, BIO_UPTODATE), 0, NULL);
 723 }
 724
 725 static void blk_add_trace_bio_bounce(struct request_queue *q, struct bio *bio)
 726 {
 727         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE);
 728 }
 729
 730 static void blk_add_trace_bio_complete(struct request_queue *q, struct bio *bio)
 731 {
 732         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE);
 733 }
 734
 735 static void blk_add_trace_bio_backmerge(struct request_queue *q,
 736                                         struct bio *bio)
 737 {
 738         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
 739 }
 740
 741 static void blk_add_trace_bio_frontmerge(struct request_queue *q,
 742                                          struct bio *bio)
 743 {
 744         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
 745 }
 746
 747 static void blk_add_trace_bio_queue(struct request_queue *q, struct bio *bio)
 748 {
 749         blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
 750 }
 751
 752 static void blk_add_trace_getrq(struct request_queue *q,
 753                                 struct bio *bio, int rw)
 754 {
 755         if (bio)
 756                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ);
 757         else {
 758                 struct blk_trace *bt = q->blk_trace;
 759
 760                 if (bt)
 761                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
 762         }
 763 }
 764
 765
 766 static void blk_add_trace_sleeprq(struct request_queue *q,
 767                                   struct bio *bio, int rw)
 768 {
 769         if (bio)
 770                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ);
 771         else {
 772                 struct blk_trace *bt = q->blk_trace;
 773
 774                 if (bt)
 775                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
 776                                         0, 0, NULL);
 777         }
 778 }
 779
 780 static void blk_add_trace_plug(struct request_queue *q)
 781 {
 782         struct blk_trace *bt = q->blk_trace;
 783
 784         if (bt)
 785                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
 786 }
 787
 788 static void blk_add_trace_unplug_io(struct request_queue *q)
 789 {
 790         struct blk_trace *bt = q->blk_trace;
 791
 792         if (bt) {
 793                 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
 794                 __be64 rpdu = cpu_to_be64(pdu);
 795
 796                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_IO, 0,
 797                                 sizeof(rpdu), &rpdu);
 798         }
 799 }
 800
 801 static void blk_add_trace_unplug_timer(struct request_queue *q)
 802 {
 803         struct blk_trace *bt = q->blk_trace;
 804
 805         if (bt) {
 806                 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
 807                 __be64 rpdu = cpu_to_be64(pdu);
 808
 809                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_TIMER, 0,
 810                                 sizeof(rpdu), &rpdu);
 811         }
 812 }
 813
 814 static void blk_add_trace_split(struct request_queue *q, struct bio *bio,
 815                                 unsigned int pdu)
 816 {
 817         struct blk_trace *bt = q->blk_trace;
 818
 819         if (bt) {
 820                 __be64 rpdu = cpu_to_be64(pdu);
 821
 822                 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 823                                 BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
 824                                 sizeof(rpdu), &rpdu);
 825         }
 826 }
 827
 828 /**
 829  * blk_add_trace_remap - Add a trace for a remap operation
 830  * @q:          queue the io is for
 831  * @bio:        the source bio
 832  * @dev:        target device
 833  * @from:       source sector
 834  * @to:         target sector
 835  *
 836  * Description:
 837  *     Device mapper or raid target sometimes need to split a bio because
 838  *     it spans a stripe (or similar). Add a trace for that action.
 839  *
 840  **/
 841 static void blk_add_trace_remap(struct request_queue *q, struct bio *bio,
 842                                        dev_t dev, sector_t from, sector_t to)
 843 {
 844         struct blk_trace *bt = q->blk_trace;
 845         struct blk_io_trace_remap r;
 846
 847         if (likely(!bt))
 848                 return;
 849
 850         r.device = cpu_to_be32(dev);
 851         r.device_from = cpu_to_be32(bio->bi_bdev->bd_dev);
 852         r.sector = cpu_to_be64(to);
 853
 854         __blk_add_trace(bt, from, bio->bi_size, bio->bi_rw, BLK_TA_REMAP,
 855                         !bio_flagged(bio, BIO_UPTODATE), sizeof(r), &r);
 856 }
 857
 858 /**
 859  * blk_add_driver_data - Add binary message with driver-specific data
 860  * @q:          queue the io is for
 861  * @rq:         io request
 862  * @data:       driver-specific data
 863  * @len:        length of driver-specific data
 864  *
 865  * Description:
 866  *     Some drivers might want to write driver-specific data per request.
 867  *
 868  **/
 869 void blk_add_driver_data(struct request_queue *q,
 870                          struct request *rq,
 871                          void *data, size_t len)
 872 {
 873         struct blk_trace *bt = q->blk_trace;
 874
 875         if (likely(!bt))
 876                 return;
 877
 878         if (blk_pc_request(rq))
 879                 __blk_add_trace(bt, 0, rq->data_len, 0, BLK_TA_DRV_DATA,
 880                                 rq->errors, len, data);
 881         else
 882                 __blk_add_trace(bt, rq->hard_sector, rq->hard_nr_sectors << 9,
 883                                 0, BLK_TA_DRV_DATA, rq->errors, len, data);
 884 }
 885 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 886
 887 static void blk_register_tracepoints(void)
 888 {
 889         int ret;
 890
 891         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort);
 892         WARN_ON(ret);
 893         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert);
 894         WARN_ON(ret);
 895         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue);
 896         WARN_ON(ret);
 897         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue);
 898         WARN_ON(ret);
 899         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete);
 900         WARN_ON(ret);
 901         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce);
 902         WARN_ON(ret);
 903         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete);
 904         WARN_ON(ret);
 905         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
 906         WARN_ON(ret);
 907         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
 908         WARN_ON(ret);
 909         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue);
 910         WARN_ON(ret);
 911         ret = register_trace_block_getrq(blk_add_trace_getrq);
 912         WARN_ON(ret);
 913         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq);
 914         WARN_ON(ret);
 915         ret = register_trace_block_plug(blk_add_trace_plug);
 916         WARN_ON(ret);
 917         ret = register_trace_block_unplug_timer(blk_add_trace_unplug_timer);
 918         WARN_ON(ret);
 919         ret = register_trace_block_unplug_io(blk_add_trace_unplug_io);
 920         WARN_ON(ret);
 921         ret = register_trace_block_split(blk_add_trace_split);
 922         WARN_ON(ret);
 923         ret = register_trace_block_remap(blk_add_trace_remap);
 924         WARN_ON(ret);
 925 }
 926
 927 static void blk_unregister_tracepoints(void)
 928 {
 929         unregister_trace_block_remap(blk_add_trace_remap);
 930         unregister_trace_block_split(blk_add_trace_split);
 931         unregister_trace_block_unplug_io(blk_add_trace_unplug_io);
 932         unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer);
 933         unregister_trace_block_plug(blk_add_trace_plug);
 934         unregister_trace_block_sleeprq(blk_add_trace_sleeprq);
 935         unregister_trace_block_getrq(blk_add_trace_getrq);
 936         unregister_trace_block_bio_queue(blk_add_trace_bio_queue);
 937         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
 938         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
 939         unregister_trace_block_bio_complete(blk_add_trace_bio_complete);
 940         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce);
 941         unregister_trace_block_rq_complete(blk_add_trace_rq_complete);
 942         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue);
 943         unregister_trace_block_rq_issue(blk_add_trace_rq_issue);
 944         unregister_trace_block_rq_insert(blk_add_trace_rq_insert);
 945         unregister_trace_block_rq_abort(blk_add_trace_rq_abort);
 946
 947         tracepoint_synchronize_unregister();
 948 }
 949
 950 /*
 951  * struct blk_io_tracer formatting routines
 952  */
 953
 954 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
 955 {
 956         int i = 0;
 957         int tc = t->action >> BLK_TC_SHIFT;
 958
 959         if (t->action == BLK_TN_MESSAGE) {
 960                 rwbs[i++] = 'N';
 961                 goto out;
 962         }
 963
 964         if (tc & BLK_TC_DISCARD)
 965                 rwbs[i++] = 'D';
 966         else if (tc & BLK_TC_WRITE)
 967                 rwbs[i++] = 'W';
 968         else if (t->bytes)
 969                 rwbs[i++] = 'R';
 970         else
 971                 rwbs[i++] = 'N';
 972
 973         if (tc & BLK_TC_AHEAD)
 974                 rwbs[i++] = 'A';
 975         if (tc & BLK_TC_BARRIER)
 976                 rwbs[i++] = 'B';
 977         if (tc & BLK_TC_SYNC)
 978                 rwbs[i++] = 'S';
 979         if (tc & BLK_TC_META)
 980                 rwbs[i++] = 'M';
 981 out:
 982         rwbs[i] = '\0';
 983 }
 984
 985 static inline
 986 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
 987 {
 988         return (const struct blk_io_trace *)ent;
 989 }
 990
 991 static inline const void *pdu_start(const struct trace_entry *ent)
 992 {
 993         return te_blk_io_trace(ent) + 1;
 994 }
 995
 996 static inline u32 t_action(const struct trace_entry *ent)
 997 {
 998         return te_blk_io_trace(ent)->action;
 999 }
1000
1001 static inline u32 t_bytes(const struct trace_entry *ent)
1002 {
1003         return te_blk_io_trace(ent)->bytes;
1004 }
1005
1006 static inline u32 t_sec(const struct trace_entry *ent)
1007 {
1008         return te_blk_io_trace(ent)->bytes >> 9;
1009 }
1010
1011 static inline unsigned long long t_sector(const struct trace_entry *ent)
1012 {
1013         return te_blk_io_trace(ent)->sector;
1014 }
1015
1016 static inline __u16 t_error(const struct trace_entry *ent)
1017 {
1018         return te_blk_io_trace(ent)->error;
1019 }
1020
1021 static __u64 get_pdu_int(const struct trace_entry *ent)
1022 {
1023         const __u64 *val = pdu_start(ent);
1024         return be64_to_cpu(*val);
1025 }
1026
1027 static void get_pdu_remap(const struct trace_entry *ent,
1028                           struct blk_io_trace_remap *r)
1029 {
1030         const struct blk_io_trace_remap *__r = pdu_start(ent);
1031         __u64 sector = __r->sector;
1032
1033         r->device = be32_to_cpu(__r->device);
1034         r->device_from = be32_to_cpu(__r->device_from);
1035         r->sector = be64_to_cpu(sector);
1036 }
1037
1038 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1039
1040 static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1041 {
1042         char rwbs[6];
1043         unsigned long long ts  = iter->ts;
1044         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1045         unsigned secs          = (unsigned long)ts;
1046         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1047
1048         fill_rwbs(rwbs, t);
1049
1050         return trace_seq_printf(&iter->seq,
1051                                 "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1052                                 MAJOR(t->device), MINOR(t->device), iter->cpu,
1053                                 secs, nsec_rem, iter->ent->pid, act, rwbs);
1054 }
1055
1056 static int blk_log_action(struct trace_iterator *iter, const char *act)
1057 {
1058         char rwbs[6];
1059         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1060
1061         fill_rwbs(rwbs, t);
1062         return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1063                                 MAJOR(t->device), MINOR(t->device), act, rwbs);
1064 }
1065
1066 static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1067 {
1068         const char *pdu_buf;
1069         int pdu_len;
1070         int i, end, ret;
1071
1072         pdu_buf = pdu_start(ent);
1073         pdu_len = te_blk_io_trace(ent)->pdu_len;
1074
1075         if (!pdu_len)
1076                 return 1;
1077
1078         /* find the last zero that needs to be printed */
1079         for (end = pdu_len - 1; end >= 0; end--)
1080                 if (pdu_buf[end])
1081                         break;
1082         end++;
1083
1084         if (!trace_seq_putc(s, '('))
1085                 return 0;
1086
1087         for (i = 0; i < pdu_len; i++) {
1088
1089                 ret = trace_seq_printf(s, "%s%02x",
1090                                        i == 0 ? "" : " ", pdu_buf[i]);
1091                 if (!ret)
1092                         return ret;
1093
1094                 /*
1095                  * stop when the rest is just zeroes and indicate so
1096                  * with a ".." appended
1097                  */
1098                 if (i == end && end != pdu_len - 1)
1099                         return trace_seq_puts(s, " ..) ");
1100         }
1101
1102         return trace_seq_puts(s, ") ");
1103 }
1104
1105 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1106 {
1107         char cmd[TASK_COMM_LEN];
1108
1109         trace_find_cmdline(ent->pid, cmd);
1110
1111         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1112                 int ret;
1113
1114                 ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1115                 if (!ret)
1116                         return 0;
1117                 ret = blk_log_dump_pdu(s, ent);
1118                 if (!ret)
1119                         return 0;
1120                 return trace_seq_printf(s, "[%s]\n", cmd);
1121         } else {
1122                 if (t_sec(ent))
1123                         return trace_seq_printf(s, "%llu + %u [%s]\n",
1124                                                 t_sector(ent), t_sec(ent), cmd);
1125                 return trace_seq_printf(s, "[%s]\n", cmd);
1126         }
1127 }
1128
1129 static int blk_log_with_error(struct trace_seq *s,
1130                               const struct trace_entry *ent)
1131 {
1132         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1133                 int ret;
1134
1135                 ret = blk_log_dump_pdu(s, ent);
1136                 if (ret)
1137                         return trace_seq_printf(s, "[%d]\n", t_error(ent));
1138                 return 0;
1139         } else {
1140                 if (t_sec(ent))
1141                         return trace_seq_printf(s, "%llu + %u [%d]\n",
1142                                                 t_sector(ent),
1143                                                 t_sec(ent), t_error(ent));
1144                 return trace_seq_printf(s, "%llu [%d]\n",
1145                                         t_sector(ent), t_error(ent));
1146         }
1147 }
1148
1149 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1150 {
1151         struct blk_io_trace_remap r = { .device = 0, };
1152
1153         get_pdu_remap(ent, &r);
1154         return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1155                                t_sector(ent),
1156                                t_sec(ent), MAJOR(r.device), MINOR(r.device),
1157                                (unsigned long long)r.sector);
1158 }
1159
1160 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1161 {
1162         char cmd[TASK_COMM_LEN];
1163
1164         trace_find_cmdline(ent->pid, cmd);
1165
1166         return trace_seq_printf(s, "[%s]\n", cmd);
1167 }
1168
1169 static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1170 {
1171         char cmd[TASK_COMM_LEN];
1172
1173         trace_find_cmdline(ent->pid, cmd);
1174
1175         return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1176 }
1177
1178 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1179 {
1180         char cmd[TASK_COMM_LEN];
1181
1182         trace_find_cmdline(ent->pid, cmd);
1183
1184         return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1185                                 get_pdu_int(ent), cmd);
1186 }
1187
1188 static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1189 {
1190         int ret;
1191         const struct blk_io_trace *t = te_blk_io_trace(ent);
1192
1193         ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1194         if (ret)
1195                 return trace_seq_putc(s, '\n');
1196         return ret;
1197 }
1198
1199 /*
1200  * struct tracer operations
1201  */
1202
1203 static void blk_tracer_print_header(struct seq_file *m)
1204 {
1205         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1206                 return;
1207         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1208                     "#  |     |     |           |   |   |\n");
1209 }
1210
1211 static void blk_tracer_start(struct trace_array *tr)
1212 {
1213         blk_tracer_enabled = true;
1214 }
1215
1216 static int blk_tracer_init(struct trace_array *tr)
1217 {
1218         blk_tr = tr;
1219         blk_tracer_start(tr);
1220         return 0;
1221 }
1222
1223 static void blk_tracer_stop(struct trace_array *tr)
1224 {
1225         blk_tracer_enabled = false;
1226 }
1227
1228 static void blk_tracer_reset(struct trace_array *tr)
1229 {
1230         blk_tracer_stop(tr);
1231 }
1232
1233 static const struct {
1234         const char *act[2];
1235         int        (*print)(struct trace_seq *s, const struct trace_entry *ent);
1236 } what2act[] = {
1237         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1238         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1239         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1240         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1241         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1242         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1243         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1244         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1245         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1246         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1247         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1248         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1249         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1250         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1251         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1252 };
1253
1254 static enum print_line_t print_one_line(struct trace_iterator *iter,
1255                                         bool classic)
1256 {
1257         struct trace_seq *s = &iter->seq;
1258         const struct blk_io_trace *t;
1259         u16 what;
1260         int ret;
1261         bool long_act;
1262         blk_log_action_t *log_action;
1263
1264         t          = te_blk_io_trace(iter->ent);
1265         what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1266         long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1267         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1268
1269         if (t->action == BLK_TN_MESSAGE) {
1270                 ret = log_action(iter, long_act ? "message" : "m");
1271                 if (ret)
1272                         ret = blk_log_msg(s, iter->ent);
1273                 goto out;
1274         }
1275
1276         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1277                 ret = trace_seq_printf(s, "Unknown action %x\n", what);
1278         else {
1279                 ret = log_action(iter, what2act[what].act[long_act]);
1280                 if (ret)
1281                         ret = what2act[what].print(s, iter->ent);
1282         }
1283 out:
1284         return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1285 }
1286
1287 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1288                                                int flags)
1289 {
1290         return print_one_line(iter, false);
1291 }
1292
1293 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1294 {
1295         struct trace_seq *s = &iter->seq;
1296         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1297         const int offset = offsetof(struct blk_io_trace, sector);
1298         struct blk_io_trace old = {
1299                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1300                 .time     = iter->ts,
1301         };
1302
1303         if (!trace_seq_putmem(s, &old, offset))
1304                 return 0;
1305         return trace_seq_putmem(s, &t->sector,
1306                                 sizeof(old) - offset + t->pdu_len);
1307 }
1308
1309 static enum print_line_t
1310 blk_trace_event_print_binary(struct trace_iterator *iter, int flags)
1311 {
1312         return blk_trace_synthesize_old_trace(iter) ?
1313                         TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1314 }
1315
1316 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1317 {
1318         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1319                 return TRACE_TYPE_UNHANDLED;
1320
1321         return print_one_line(iter, true);
1322 }
1323
1324 static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
1325 {
1326         /* don't output context-info for blk_classic output */
1327         if (bit == TRACE_BLK_OPT_CLASSIC) {
1328                 if (set)
1329                         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1330                 else
1331                         trace_flags |= TRACE_ITER_CONTEXT_INFO;
1332         }
1333         return 0;
1334 }
1335
1336 static struct tracer blk_tracer __read_mostly = {
1337         .name           = "blk",
1338         .init           = blk_tracer_init,
1339         .reset          = blk_tracer_reset,
1340         .start          = blk_tracer_start,
1341         .stop           = blk_tracer_stop,
1342         .print_header   = blk_tracer_print_header,
1343         .print_line     = blk_tracer_print_line,
1344         .flags          = &blk_tracer_flags,
1345         .set_flag       = blk_tracer_set_flag,
1346 };
1347
1348 static struct trace_event trace_blk_event = {
1349         .type           = TRACE_BLK,
1350         .trace          = blk_trace_event_print,
1351         .binary         = blk_trace_event_print_binary,
1352 };
1353
1354 static int __init init_blk_tracer(void)
1355 {
1356         if (!register_ftrace_event(&trace_blk_event)) {
1357                 pr_warning("Warning: could not register block events\n");
1358                 return 1;
1359         }
1360
1361         if (register_tracer(&blk_tracer) != 0) {
1362                 pr_warning("Warning: could not register the block tracer\n");
1363                 unregister_ftrace_event(&trace_blk_event);
1364                 return 1;
1365         }
1366
1367         return 0;
1368 }
1369
1370 device_initcall(init_blk_tracer);
1371
1372 static int blk_trace_remove_queue(struct request_queue *q)
1373 {
1374         struct blk_trace *bt;
1375
1376         bt = xchg(&q->blk_trace, NULL);
1377         if (bt == NULL)
1378                 return -EINVAL;
1379
1380         if (atomic_dec_and_test(&blk_probes_ref))
1381                 blk_unregister_tracepoints();
1382
1383         blk_trace_free(bt);
1384         return 0;
1385 }
1386
1387 /*
1388  * Setup everything required to start tracing
1389  */
1390 static int blk_trace_setup_queue(struct request_queue *q,
1391                                  struct block_device *bdev)
1392 {
1393         struct blk_trace *old_bt, *bt = NULL;
1394         int ret = -ENOMEM;
1395
1396         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1397         if (!bt)
1398                 return -ENOMEM;
1399
1400         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1401         if (!bt->msg_data)
1402                 goto free_bt;
1403
1404         bt->dev = bdev->bd_dev;
1405         bt->act_mask = (u16)-1;
1406
1407         blk_trace_setup_lba(bt, bdev);
1408
1409         old_bt = xchg(&q->blk_trace, bt);
1410         if (old_bt != NULL) {
1411                 (void)xchg(&q->blk_trace, old_bt);
1412                 ret = -EBUSY;
1413                 goto free_bt;
1414         }
1415
1416         if (atomic_inc_return(&blk_probes_ref) == 1)
1417                 blk_register_tracepoints();
1418         return 0;
1419
1420 free_bt:
1421         blk_trace_free(bt);
1422         return ret;
1423 }
1424
1425 /*
1426  * sysfs interface to enable and configure tracing
1427  */
1428
1429 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1430                                          struct device_attribute *attr,
1431                                          char *buf);
1432 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1433                                           struct device_attribute *attr,
1434                                           const char *buf, size_t count);
1435 #define BLK_TRACE_DEVICE_ATTR(_name) \
1436         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1437                     sysfs_blk_trace_attr_show, \
1438                     sysfs_blk_trace_attr_store)
1439
1440 static BLK_TRACE_DEVICE_ATTR(enable);
1441 static BLK_TRACE_DEVICE_ATTR(act_mask);
1442 static BLK_TRACE_DEVICE_ATTR(pid);
1443 static BLK_TRACE_DEVICE_ATTR(start_lba);
1444 static BLK_TRACE_DEVICE_ATTR(end_lba);
1445
1446 static struct attribute *blk_trace_attrs[] = {
1447         &dev_attr_enable.attr,
1448         &dev_attr_act_mask.attr,
1449         &dev_attr_pid.attr,
1450         &dev_attr_start_lba.attr,
1451         &dev_attr_end_lba.attr,
1452         NULL
1453 };
1454
1455 struct attribute_group blk_trace_attr_group = {
1456         .name  = "trace",
1457         .attrs = blk_trace_attrs,
1458 };
1459
1460 static const struct {
1461         int mask;
1462         const char *str;
1463 } mask_maps[] = {
1464         { BLK_TC_READ,          "read"          },
1465         { BLK_TC_WRITE,         "write"         },
1466         { BLK_TC_BARRIER,       "barrier"       },
1467         { BLK_TC_SYNC,          "sync"          },
1468         { BLK_TC_QUEUE,         "queue"         },
1469         { BLK_TC_REQUEUE,       "requeue"       },
1470         { BLK_TC_ISSUE,         "issue"         },
1471         { BLK_TC_COMPLETE,      "complete"      },
1472         { BLK_TC_FS,            "fs"            },
1473         { BLK_TC_PC,            "pc"            },
1474         { BLK_TC_AHEAD,         "ahead"         },
1475         { BLK_TC_META,          "meta"          },
1476         { BLK_TC_DISCARD,       "discard"       },
1477         { BLK_TC_DRV_DATA,      "drv_data"      },
1478 };
1479
1480 static int blk_trace_str2mask(const char *str)
1481 {
1482         int i;
1483         int mask = 0;
1484         char *buf, *s, *token;
1485
1486         buf = kstrdup(str, GFP_KERNEL);
1487         if (buf == NULL)
1488                 return -ENOMEM;
1489         s = strstrip(buf);
1490
1491         while (1) {
1492                 token = strsep(&s, ",");
1493                 if (token == NULL)
1494                         break;
1495
1496                 if (*token == '\0')
1497                         continue;
1498
1499                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1500                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1501                                 mask |= mask_maps[i].mask;
1502                                 break;
1503                         }
1504                 }
1505                 if (i == ARRAY_SIZE(mask_maps)) {
1506                         mask = -EINVAL;
1507                         break;
1508                 }
1509         }
1510         kfree(buf);
1511
1512         return mask;
1513 }
1514
1515 static ssize_t blk_trace_mask2str(char *buf, int mask)
1516 {
1517         int i;
1518         char *p = buf;
1519
1520         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1521                 if (mask & mask_maps[i].mask) {
1522                         p += sprintf(p, "%s%s",
1523                                     (p == buf) ? "" : ",", mask_maps[i].str);
1524                 }
1525         }
1526         *p++ = '\n';
1527
1528         return p - buf;
1529 }
1530
1531 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1532 {
1533         if (bdev->bd_disk == NULL)
1534                 return NULL;
1535
1536         return bdev_get_queue(bdev);
1537 }
1538
1539 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1540                                          struct device_attribute *attr,
1541                                          char *buf)
1542 {
1543         struct hd_struct *p = dev_to_part(dev);
1544         struct request_queue *q;
1545         struct block_device *bdev;
1546         ssize_t ret = -ENXIO;
1547
1548         lock_kernel();
1549         bdev = bdget(part_devt(p));
1550         if (bdev == NULL)
1551                 goto out_unlock_kernel;
1552
1553         q = blk_trace_get_queue(bdev);
1554         if (q == NULL)
1555                 goto out_bdput;
1556
1557         mutex_lock(&bdev->bd_mutex);
1558
1559         if (attr == &dev_attr_enable) {
1560                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1561                 goto out_unlock_bdev;
1562         }
1563
1564         if (q->blk_trace == NULL)
1565                 ret = sprintf(buf, "disabled\n");
1566         else if (attr == &dev_attr_act_mask)
1567                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1568         else if (attr == &dev_attr_pid)
1569                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1570         else if (attr == &dev_attr_start_lba)
1571                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1572         else if (attr == &dev_attr_end_lba)
1573                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1574
1575 out_unlock_bdev:
1576         mutex_unlock(&bdev->bd_mutex);
1577 out_bdput:
1578         bdput(bdev);
1579 out_unlock_kernel:
1580         unlock_kernel();
1581         return ret;
1582 }
1583
1584 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1585                                           struct device_attribute *attr,
1586                                           const char *buf, size_t count)
1587 {
1588         struct block_device *bdev;
1589         struct request_queue *q;
1590         struct hd_struct *p;
1591         u64 value;
1592         ssize_t ret = -EINVAL;
1593
1594         if (count == 0)
1595                 goto out;
1596
1597         if (attr == &dev_attr_act_mask) {
1598                 if (sscanf(buf, "%llx", &value) != 1) {
1599                         /* Assume it is a list of trace category names */
1600                         ret = blk_trace_str2mask(buf);
1601                         if (ret < 0)
1602                                 goto out;
1603                         value = ret;
1604                 }
1605         } else if (sscanf(buf, "%llu", &value) != 1)
1606                 goto out;
1607
1608         ret = -ENXIO;
1609
1610         lock_kernel();
1611         p = dev_to_part(dev);
1612         bdev = bdget(part_devt(p));
1613         if (bdev == NULL)
1614                 goto out_unlock_kernel;
1615
1616         q = blk_trace_get_queue(bdev);
1617         if (q == NULL)
1618                 goto out_bdput;
1619
1620         mutex_lock(&bdev->bd_mutex);
1621
1622         if (attr == &dev_attr_enable) {
1623                 if (value)
1624                         ret = blk_trace_setup_queue(q, bdev);
1625                 else
1626                         ret = blk_trace_remove_queue(q);
1627                 goto out_unlock_bdev;
1628         }
1629
1630         ret = 0;
1631         if (q->blk_trace == NULL)
1632                 ret = blk_trace_setup_queue(q, bdev);
1633
1634         if (ret == 0) {
1635                 if (attr == &dev_attr_act_mask)
1636                         q->blk_trace->act_mask = value;
1637                 else if (attr == &dev_attr_pid)
1638                         q->blk_trace->pid = value;
1639                 else if (attr == &dev_attr_start_lba)
1640                         q->blk_trace->start_lba = value;
1641                 else if (attr == &dev_attr_end_lba)
1642                         q->blk_trace->end_lba = value;
1643         }
1644
1645 out_unlock_bdev:
1646         mutex_unlock(&bdev->bd_mutex);
1647 out_bdput:
1648         bdput(bdev);
1649 out_unlock_kernel:
1650         unlock_kernel();
1651 out:
1652         return ret ? ret : count;
1653 }
1654
1655 int blk_trace_init_sysfs(struct device *dev)
1656 {
1657         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1658 }
1659