linux/kernel/trace/blktrace.c
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   1/*
   2 * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 * GNU General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public License
  14 * along with this program; if not, write to the Free Software
  15 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  16 *
  17 */
  18#include <linux/kernel.h>
  19#include <linux/blkdev.h>
  20#include <linux/blktrace_api.h>
  21#include <linux/percpu.h>
  22#include <linux/init.h>
  23#include <linux/mutex.h>
  24#include <linux/slab.h>
  25#include <linux/debugfs.h>
  26#include <linux/export.h>
  27#include <linux/time.h>
  28#include <linux/uaccess.h>
  29
  30#include <trace/events/block.h>
  31
  32#include "trace_output.h"
  33
  34#ifdef CONFIG_BLK_DEV_IO_TRACE
  35
  36static unsigned int blktrace_seq __read_mostly = 1;
  37
  38static struct trace_array *blk_tr;
  39static bool blk_tracer_enabled __read_mostly;
  40
  41/* Select an alternative, minimalistic output than the original one */
  42#define TRACE_BLK_OPT_CLASSIC   0x1
  43
  44static struct tracer_opt blk_tracer_opts[] = {
  45        /* Default disable the minimalistic output */
  46        { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
  47        { }
  48};
  49
  50static struct tracer_flags blk_tracer_flags = {
  51        .val  = 0,
  52        .opts = blk_tracer_opts,
  53};
  54
  55/* Global reference count of probes */
  56static atomic_t blk_probes_ref = ATOMIC_INIT(0);
  57
  58static void blk_register_tracepoints(void);
  59static void blk_unregister_tracepoints(void);
  60
  61/*
  62 * Send out a notify message.
  63 */
  64static void trace_note(struct blk_trace *bt, pid_t pid, int action,
  65                       const void *data, size_t len)
  66{
  67        struct blk_io_trace *t;
  68        struct ring_buffer_event *event = NULL;
  69        struct ring_buffer *buffer = NULL;
  70        int pc = 0;
  71        int cpu = smp_processor_id();
  72        bool blk_tracer = blk_tracer_enabled;
  73
  74        if (blk_tracer) {
  75                buffer = blk_tr->buffer;
  76                pc = preempt_count();
  77                event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
  78                                                  sizeof(*t) + len,
  79                                                  0, pc);
  80                if (!event)
  81                        return;
  82                t = ring_buffer_event_data(event);
  83                goto record_it;
  84        }
  85
  86        if (!bt->rchan)
  87                return;
  88
  89        t = relay_reserve(bt->rchan, sizeof(*t) + len);
  90        if (t) {
  91                t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
  92                t->time = ktime_to_ns(ktime_get());
  93record_it:
  94                t->device = bt->dev;
  95                t->action = action;
  96                t->pid = pid;
  97                t->cpu = cpu;
  98                t->pdu_len = len;
  99                memcpy((void *) t + sizeof(*t), data, len);
 100
 101                if (blk_tracer)
 102                        trace_buffer_unlock_commit(buffer, event, 0, pc);
 103        }
 104}
 105
 106/*
 107 * Send out a notify for this process, if we haven't done so since a trace
 108 * started
 109 */
 110static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
 111{
 112        tsk->btrace_seq = blktrace_seq;
 113        trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));
 114}
 115
 116static void trace_note_time(struct blk_trace *bt)
 117{
 118        struct timespec now;
 119        unsigned long flags;
 120        u32 words[2];
 121
 122        getnstimeofday(&now);
 123        words[0] = now.tv_sec;
 124        words[1] = now.tv_nsec;
 125
 126        local_irq_save(flags);
 127        trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
 128        local_irq_restore(flags);
 129}
 130
 131void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 132{
 133        int n;
 134        va_list args;
 135        unsigned long flags;
 136        char *buf;
 137
 138        if (unlikely(bt->trace_state != Blktrace_running &&
 139                     !blk_tracer_enabled))
 140                return;
 141
 142        /*
 143         * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
 144         * message to the trace.
 145         */
 146        if (!(bt->act_mask & BLK_TC_NOTIFY))
 147                return;
 148
 149        local_irq_save(flags);
 150        buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
 151        va_start(args, fmt);
 152        n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 153        va_end(args);
 154
 155        trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
 156        local_irq_restore(flags);
 157}
 158EXPORT_SYMBOL_GPL(__trace_note_message);
 159
 160static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
 161                         pid_t pid)
 162{
 163        if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
 164                return 1;
 165        if (sector && (sector < bt->start_lba || sector > bt->end_lba))
 166                return 1;
 167        if (bt->pid && pid != bt->pid)
 168                return 1;
 169
 170        return 0;
 171}
 172
 173/*
 174 * Data direction bit lookup
 175 */
 176static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
 177                                 BLK_TC_ACT(BLK_TC_WRITE) };
 178
 179#define BLK_TC_RAHEAD           BLK_TC_AHEAD
 180
 181/* The ilog2() calls fall out because they're constant */
 182#define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
 183          (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
 184
 185/*
 186 * The worker for the various blk_add_trace*() types. Fills out a
 187 * blk_io_trace structure and places it in a per-cpu subbuffer.
 188 */
 189static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 190                     int rw, u32 what, int error, int pdu_len, void *pdu_data)
 191{
 192        struct task_struct *tsk = current;
 193        struct ring_buffer_event *event = NULL;
 194        struct ring_buffer *buffer = NULL;
 195        struct blk_io_trace *t;
 196        unsigned long flags = 0;
 197        unsigned long *sequence;
 198        pid_t pid;
 199        int cpu, pc = 0;
 200        bool blk_tracer = blk_tracer_enabled;
 201
 202        if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
 203                return;
 204
 205        what |= ddir_act[rw & WRITE];
 206        what |= MASK_TC_BIT(rw, SYNC);
 207        what |= MASK_TC_BIT(rw, RAHEAD);
 208        what |= MASK_TC_BIT(rw, META);
 209        what |= MASK_TC_BIT(rw, DISCARD);
 210        what |= MASK_TC_BIT(rw, FLUSH);
 211        what |= MASK_TC_BIT(rw, FUA);
 212
 213        pid = tsk->pid;
 214        if (act_log_check(bt, what, sector, pid))
 215                return;
 216        cpu = raw_smp_processor_id();
 217
 218        if (blk_tracer) {
 219                tracing_record_cmdline(current);
 220
 221                buffer = blk_tr->buffer;
 222                pc = preempt_count();
 223                event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 224                                                  sizeof(*t) + pdu_len,
 225                                                  0, pc);
 226                if (!event)
 227                        return;
 228                t = ring_buffer_event_data(event);
 229                goto record_it;
 230        }
 231
 232        /*
 233         * A word about the locking here - we disable interrupts to reserve
 234         * some space in the relay per-cpu buffer, to prevent an irq
 235         * from coming in and stepping on our toes.
 236         */
 237        local_irq_save(flags);
 238
 239        if (unlikely(tsk->btrace_seq != blktrace_seq))
 240                trace_note_tsk(bt, tsk);
 241
 242        t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
 243        if (t) {
 244                sequence = per_cpu_ptr(bt->sequence, cpu);
 245
 246                t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 247                t->sequence = ++(*sequence);
 248                t->time = ktime_to_ns(ktime_get());
 249record_it:
 250                /*
 251                 * These two are not needed in ftrace as they are in the
 252                 * generic trace_entry, filled by tracing_generic_entry_update,
 253                 * but for the trace_event->bin() synthesizer benefit we do it
 254                 * here too.
 255                 */
 256                t->cpu = cpu;
 257                t->pid = pid;
 258
 259                t->sector = sector;
 260                t->bytes = bytes;
 261                t->action = what;
 262                t->device = bt->dev;
 263                t->error = error;
 264                t->pdu_len = pdu_len;
 265
 266                if (pdu_len)
 267                        memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
 268
 269                if (blk_tracer) {
 270                        trace_buffer_unlock_commit(buffer, event, 0, pc);
 271                        return;
 272                }
 273        }
 274
 275        local_irq_restore(flags);
 276}
 277
 278static struct dentry *blk_tree_root;
 279static DEFINE_MUTEX(blk_tree_mutex);
 280
 281static void blk_trace_free(struct blk_trace *bt)
 282{
 283        debugfs_remove(bt->msg_file);
 284        debugfs_remove(bt->dropped_file);
 285        relay_close(bt->rchan);
 286        debugfs_remove(bt->dir);
 287        free_percpu(bt->sequence);
 288        free_percpu(bt->msg_data);
 289        kfree(bt);
 290}
 291
 292static void blk_trace_cleanup(struct blk_trace *bt)
 293{
 294        blk_trace_free(bt);
 295        if (atomic_dec_and_test(&blk_probes_ref))
 296                blk_unregister_tracepoints();
 297}
 298
 299int blk_trace_remove(struct request_queue *q)
 300{
 301        struct blk_trace *bt;
 302
 303        bt = xchg(&q->blk_trace, NULL);
 304        if (!bt)
 305                return -EINVAL;
 306
 307        if (bt->trace_state != Blktrace_running)
 308                blk_trace_cleanup(bt);
 309
 310        return 0;
 311}
 312EXPORT_SYMBOL_GPL(blk_trace_remove);
 313
 314static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
 315                                size_t count, loff_t *ppos)
 316{
 317        struct blk_trace *bt = filp->private_data;
 318        char buf[16];
 319
 320        snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
 321
 322        return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 323}
 324
 325static const struct file_operations blk_dropped_fops = {
 326        .owner =        THIS_MODULE,
 327        .open =         simple_open,
 328        .read =         blk_dropped_read,
 329        .llseek =       default_llseek,
 330};
 331
 332static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 333                                size_t count, loff_t *ppos)
 334{
 335        char *msg;
 336        struct blk_trace *bt;
 337
 338        if (count >= BLK_TN_MAX_MSG)
 339                return -EINVAL;
 340
 341        msg = kmalloc(count + 1, GFP_KERNEL);
 342        if (msg == NULL)
 343                return -ENOMEM;
 344
 345        if (copy_from_user(msg, buffer, count)) {
 346                kfree(msg);
 347                return -EFAULT;
 348        }
 349
 350        msg[count] = '\0';
 351        bt = filp->private_data;
 352        __trace_note_message(bt, "%s", msg);
 353        kfree(msg);
 354
 355        return count;
 356}
 357
 358static const struct file_operations blk_msg_fops = {
 359        .owner =        THIS_MODULE,
 360        .open =         simple_open,
 361        .write =        blk_msg_write,
 362        .llseek =       noop_llseek,
 363};
 364
 365/*
 366 * Keep track of how many times we encountered a full subbuffer, to aid
 367 * the user space app in telling how many lost events there were.
 368 */
 369static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
 370                                     void *prev_subbuf, size_t prev_padding)
 371{
 372        struct blk_trace *bt;
 373
 374        if (!relay_buf_full(buf))
 375                return 1;
 376
 377        bt = buf->chan->private_data;
 378        atomic_inc(&bt->dropped);
 379        return 0;
 380}
 381
 382static int blk_remove_buf_file_callback(struct dentry *dentry)
 383{
 384        debugfs_remove(dentry);
 385
 386        return 0;
 387}
 388
 389static struct dentry *blk_create_buf_file_callback(const char *filename,
 390                                                   struct dentry *parent,
 391                                                   umode_t mode,
 392                                                   struct rchan_buf *buf,
 393                                                   int *is_global)
 394{
 395        return debugfs_create_file(filename, mode, parent, buf,
 396                                        &relay_file_operations);
 397}
 398
 399static struct rchan_callbacks blk_relay_callbacks = {
 400        .subbuf_start           = blk_subbuf_start_callback,
 401        .create_buf_file        = blk_create_buf_file_callback,
 402        .remove_buf_file        = blk_remove_buf_file_callback,
 403};
 404
 405static void blk_trace_setup_lba(struct blk_trace *bt,
 406                                struct block_device *bdev)
 407{
 408        struct hd_struct *part = NULL;
 409
 410        if (bdev)
 411                part = bdev->bd_part;
 412
 413        if (part) {
 414                bt->start_lba = part->start_sect;
 415                bt->end_lba = part->start_sect + part->nr_sects;
 416        } else {
 417                bt->start_lba = 0;
 418                bt->end_lba = -1ULL;
 419        }
 420}
 421
 422/*
 423 * Setup everything required to start tracing
 424 */
 425int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 426                       struct block_device *bdev,
 427                       struct blk_user_trace_setup *buts)
 428{
 429        struct blk_trace *old_bt, *bt = NULL;
 430        struct dentry *dir = NULL;
 431        int ret, i;
 432
 433        if (!buts->buf_size || !buts->buf_nr)
 434                return -EINVAL;
 435
 436        strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 437        buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 438
 439        /*
 440         * some device names have larger paths - convert the slashes
 441         * to underscores for this to work as expected
 442         */
 443        for (i = 0; i < strlen(buts->name); i++)
 444                if (buts->name[i] == '/')
 445                        buts->name[i] = '_';
 446
 447        bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 448        if (!bt)
 449                return -ENOMEM;
 450
 451        ret = -ENOMEM;
 452        bt->sequence = alloc_percpu(unsigned long);
 453        if (!bt->sequence)
 454                goto err;
 455
 456        bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 457        if (!bt->msg_data)
 458                goto err;
 459
 460        ret = -ENOENT;
 461
 462        mutex_lock(&blk_tree_mutex);
 463        if (!blk_tree_root) {
 464                blk_tree_root = debugfs_create_dir("block", NULL);
 465                if (!blk_tree_root) {
 466                        mutex_unlock(&blk_tree_mutex);
 467                        goto err;
 468                }
 469        }
 470        mutex_unlock(&blk_tree_mutex);
 471
 472        dir = debugfs_create_dir(buts->name, blk_tree_root);
 473
 474        if (!dir)
 475                goto err;
 476
 477        bt->dir = dir;
 478        bt->dev = dev;
 479        atomic_set(&bt->dropped, 0);
 480
 481        ret = -EIO;
 482        bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 483                                               &blk_dropped_fops);
 484        if (!bt->dropped_file)
 485                goto err;
 486
 487        bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 488        if (!bt->msg_file)
 489                goto err;
 490
 491        bt->rchan = relay_open("trace", dir, buts->buf_size,
 492                                buts->buf_nr, &blk_relay_callbacks, bt);
 493        if (!bt->rchan)
 494                goto err;
 495
 496        bt->act_mask = buts->act_mask;
 497        if (!bt->act_mask)
 498                bt->act_mask = (u16) -1;
 499
 500        blk_trace_setup_lba(bt, bdev);
 501
 502        /* overwrite with user settings */
 503        if (buts->start_lba)
 504                bt->start_lba = buts->start_lba;
 505        if (buts->end_lba)
 506                bt->end_lba = buts->end_lba;
 507
 508        bt->pid = buts->pid;
 509        bt->trace_state = Blktrace_setup;
 510
 511        ret = -EBUSY;
 512        old_bt = xchg(&q->blk_trace, bt);
 513        if (old_bt) {
 514                (void) xchg(&q->blk_trace, old_bt);
 515                goto err;
 516        }
 517
 518        if (atomic_inc_return(&blk_probes_ref) == 1)
 519                blk_register_tracepoints();
 520
 521        return 0;
 522err:
 523        blk_trace_free(bt);
 524        return ret;
 525}
 526
 527int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 528                    struct block_device *bdev,
 529                    char __user *arg)
 530{
 531        struct blk_user_trace_setup buts;
 532        int ret;
 533
 534        ret = copy_from_user(&buts, arg, sizeof(buts));
 535        if (ret)
 536                return -EFAULT;
 537
 538        ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 539        if (ret)
 540                return ret;
 541
 542        if (copy_to_user(arg, &buts, sizeof(buts))) {
 543                blk_trace_remove(q);
 544                return -EFAULT;
 545        }
 546        return 0;
 547}
 548EXPORT_SYMBOL_GPL(blk_trace_setup);
 549
 550#if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 551static int compat_blk_trace_setup(struct request_queue *q, char *name,
 552                                  dev_t dev, struct block_device *bdev,
 553                                  char __user *arg)
 554{
 555        struct blk_user_trace_setup buts;
 556        struct compat_blk_user_trace_setup cbuts;
 557        int ret;
 558
 559        if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
 560                return -EFAULT;
 561
 562        buts = (struct blk_user_trace_setup) {
 563                .act_mask = cbuts.act_mask,
 564                .buf_size = cbuts.buf_size,
 565                .buf_nr = cbuts.buf_nr,
 566                .start_lba = cbuts.start_lba,
 567                .end_lba = cbuts.end_lba,
 568                .pid = cbuts.pid,
 569        };
 570        memcpy(&buts.name, &cbuts.name, 32);
 571
 572        ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 573        if (ret)
 574                return ret;
 575
 576        if (copy_to_user(arg, &buts.name, 32)) {
 577                blk_trace_remove(q);
 578                return -EFAULT;
 579        }
 580
 581        return 0;
 582}
 583#endif
 584
 585int blk_trace_startstop(struct request_queue *q, int start)
 586{
 587        int ret;
 588        struct blk_trace *bt = q->blk_trace;
 589
 590        if (bt == NULL)
 591                return -EINVAL;
 592
 593        /*
 594         * For starting a trace, we can transition from a setup or stopped
 595         * trace. For stopping a trace, the state must be running
 596         */
 597        ret = -EINVAL;
 598        if (start) {
 599                if (bt->trace_state == Blktrace_setup ||
 600                    bt->trace_state == Blktrace_stopped) {
 601                        blktrace_seq++;
 602                        smp_mb();
 603                        bt->trace_state = Blktrace_running;
 604
 605                        trace_note_time(bt);
 606                        ret = 0;
 607                }
 608        } else {
 609                if (bt->trace_state == Blktrace_running) {
 610                        bt->trace_state = Blktrace_stopped;
 611                        relay_flush(bt->rchan);
 612                        ret = 0;
 613                }
 614        }
 615
 616        return ret;
 617}
 618EXPORT_SYMBOL_GPL(blk_trace_startstop);
 619
 620/**
 621 * blk_trace_ioctl: - handle the ioctls associated with tracing
 622 * @bdev:       the block device
 623 * @cmd:        the ioctl cmd
 624 * @arg:        the argument data, if any
 625 *
 626 **/
 627int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 628{
 629        struct request_queue *q;
 630        int ret, start = 0;
 631        char b[BDEVNAME_SIZE];
 632
 633        q = bdev_get_queue(bdev);
 634        if (!q)
 635                return -ENXIO;
 636
 637        mutex_lock(&bdev->bd_mutex);
 638
 639        switch (cmd) {
 640        case BLKTRACESETUP:
 641                bdevname(bdev, b);
 642                ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 643                break;
 644#if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 645        case BLKTRACESETUP32:
 646                bdevname(bdev, b);
 647                ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 648                break;
 649#endif
 650        case BLKTRACESTART:
 651                start = 1;
 652        case BLKTRACESTOP:
 653                ret = blk_trace_startstop(q, start);
 654                break;
 655        case BLKTRACETEARDOWN:
 656                ret = blk_trace_remove(q);
 657                break;
 658        default:
 659                ret = -ENOTTY;
 660                break;
 661        }
 662
 663        mutex_unlock(&bdev->bd_mutex);
 664        return ret;
 665}
 666
 667/**
 668 * blk_trace_shutdown: - stop and cleanup trace structures
 669 * @q:    the request queue associated with the device
 670 *
 671 **/
 672void blk_trace_shutdown(struct request_queue *q)
 673{
 674        if (q->blk_trace) {
 675                blk_trace_startstop(q, 0);
 676                blk_trace_remove(q);
 677        }
 678}
 679
 680/*
 681 * blktrace probes
 682 */
 683
 684/**
 685 * blk_add_trace_rq - Add a trace for a request oriented action
 686 * @q:          queue the io is for
 687 * @rq:         the source request
 688 * @what:       the action
 689 *
 690 * Description:
 691 *     Records an action against a request. Will log the bio offset + size.
 692 *
 693 **/
 694static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 695                             u32 what)
 696{
 697        struct blk_trace *bt = q->blk_trace;
 698
 699        if (likely(!bt))
 700                return;
 701
 702        if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
 703                what |= BLK_TC_ACT(BLK_TC_PC);
 704                __blk_add_trace(bt, 0, blk_rq_bytes(rq), rq->cmd_flags,
 705                                what, rq->errors, rq->cmd_len, rq->cmd);
 706        } else  {
 707                what |= BLK_TC_ACT(BLK_TC_FS);
 708                __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 709                                rq->cmd_flags, what, rq->errors, 0, NULL);
 710        }
 711}
 712
 713static void blk_add_trace_rq_abort(void *ignore,
 714                                   struct request_queue *q, struct request *rq)
 715{
 716        blk_add_trace_rq(q, rq, BLK_TA_ABORT);
 717}
 718
 719static void blk_add_trace_rq_insert(void *ignore,
 720                                    struct request_queue *q, struct request *rq)
 721{
 722        blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 723}
 724
 725static void blk_add_trace_rq_issue(void *ignore,
 726                                   struct request_queue *q, struct request *rq)
 727{
 728        blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
 729}
 730
 731static void blk_add_trace_rq_requeue(void *ignore,
 732                                     struct request_queue *q,
 733                                     struct request *rq)
 734{
 735        blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
 736}
 737
 738static void blk_add_trace_rq_complete(void *ignore,
 739                                      struct request_queue *q,
 740                                      struct request *rq)
 741{
 742        blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
 743}
 744
 745/**
 746 * blk_add_trace_bio - Add a trace for a bio oriented action
 747 * @q:          queue the io is for
 748 * @bio:        the source bio
 749 * @what:       the action
 750 * @error:      error, if any
 751 *
 752 * Description:
 753 *     Records an action against a bio. Will log the bio offset + size.
 754 *
 755 **/
 756static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 757                              u32 what, int error)
 758{
 759        struct blk_trace *bt = q->blk_trace;
 760
 761        if (likely(!bt))
 762                return;
 763
 764        if (!error && !bio_flagged(bio, BIO_UPTODATE))
 765                error = EIO;
 766
 767        __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
 768                        error, 0, NULL);
 769}
 770
 771static void blk_add_trace_bio_bounce(void *ignore,
 772                                     struct request_queue *q, struct bio *bio)
 773{
 774        blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
 775}
 776
 777static void blk_add_trace_bio_complete(void *ignore,
 778                                       struct request_queue *q, struct bio *bio,
 779                                       int error)
 780{
 781        blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
 782}
 783
 784static void blk_add_trace_bio_backmerge(void *ignore,
 785                                        struct request_queue *q,
 786                                        struct bio *bio)
 787{
 788        blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
 789}
 790
 791static void blk_add_trace_bio_frontmerge(void *ignore,
 792                                         struct request_queue *q,
 793                                         struct bio *bio)
 794{
 795        blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
 796}
 797
 798static void blk_add_trace_bio_queue(void *ignore,
 799                                    struct request_queue *q, struct bio *bio)
 800{
 801        blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
 802}
 803
 804static void blk_add_trace_getrq(void *ignore,
 805                                struct request_queue *q,
 806                                struct bio *bio, int rw)
 807{
 808        if (bio)
 809                blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
 810        else {
 811                struct blk_trace *bt = q->blk_trace;
 812
 813                if (bt)
 814                        __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
 815        }
 816}
 817
 818
 819static void blk_add_trace_sleeprq(void *ignore,
 820                                  struct request_queue *q,
 821                                  struct bio *bio, int rw)
 822{
 823        if (bio)
 824                blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
 825        else {
 826                struct blk_trace *bt = q->blk_trace;
 827
 828                if (bt)
 829                        __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
 830                                        0, 0, NULL);
 831        }
 832}
 833
 834static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 835{
 836        struct blk_trace *bt = q->blk_trace;
 837
 838        if (bt)
 839                __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
 840}
 841
 842static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 843                                    unsigned int depth, bool explicit)
 844{
 845        struct blk_trace *bt = q->blk_trace;
 846
 847        if (bt) {
 848                __be64 rpdu = cpu_to_be64(depth);
 849                u32 what;
 850
 851                if (explicit)
 852                        what = BLK_TA_UNPLUG_IO;
 853                else
 854                        what = BLK_TA_UNPLUG_TIMER;
 855
 856                __blk_add_trace(bt, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu);
 857        }
 858}
 859
 860static void blk_add_trace_split(void *ignore,
 861                                struct request_queue *q, struct bio *bio,
 862                                unsigned int pdu)
 863{
 864        struct blk_trace *bt = q->blk_trace;
 865
 866        if (bt) {
 867                __be64 rpdu = cpu_to_be64(pdu);
 868
 869                __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 870                                BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
 871                                sizeof(rpdu), &rpdu);
 872        }
 873}
 874
 875/**
 876 * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
 877 * @ignore:     trace callback data parameter (not used)
 878 * @q:          queue the io is for
 879 * @bio:        the source bio
 880 * @dev:        target device
 881 * @from:       source sector
 882 *
 883 * Description:
 884 *     Device mapper or raid target sometimes need to split a bio because
 885 *     it spans a stripe (or similar). Add a trace for that action.
 886 *
 887 **/
 888static void blk_add_trace_bio_remap(void *ignore,
 889                                    struct request_queue *q, struct bio *bio,
 890                                    dev_t dev, sector_t from)
 891{
 892        struct blk_trace *bt = q->blk_trace;
 893        struct blk_io_trace_remap r;
 894
 895        if (likely(!bt))
 896                return;
 897
 898        r.device_from = cpu_to_be32(dev);
 899        r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
 900        r.sector_from = cpu_to_be64(from);
 901
 902        __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 903                        BLK_TA_REMAP, !bio_flagged(bio, BIO_UPTODATE),
 904                        sizeof(r), &r);
 905}
 906
 907/**
 908 * blk_add_trace_rq_remap - Add a trace for a request-remap operation
 909 * @ignore:     trace callback data parameter (not used)
 910 * @q:          queue the io is for
 911 * @rq:         the source request
 912 * @dev:        target device
 913 * @from:       source sector
 914 *
 915 * Description:
 916 *     Device mapper remaps request to other devices.
 917 *     Add a trace for that action.
 918 *
 919 **/
 920static void blk_add_trace_rq_remap(void *ignore,
 921                                   struct request_queue *q,
 922                                   struct request *rq, dev_t dev,
 923                                   sector_t from)
 924{
 925        struct blk_trace *bt = q->blk_trace;
 926        struct blk_io_trace_remap r;
 927
 928        if (likely(!bt))
 929                return;
 930
 931        r.device_from = cpu_to_be32(dev);
 932        r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
 933        r.sector_from = cpu_to_be64(from);
 934
 935        __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
 936                        rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
 937                        sizeof(r), &r);
 938}
 939
 940/**
 941 * blk_add_driver_data - Add binary message with driver-specific data
 942 * @q:          queue the io is for
 943 * @rq:         io request
 944 * @data:       driver-specific data
 945 * @len:        length of driver-specific data
 946 *
 947 * Description:
 948 *     Some drivers might want to write driver-specific data per request.
 949 *
 950 **/
 951void blk_add_driver_data(struct request_queue *q,
 952                         struct request *rq,
 953                         void *data, size_t len)
 954{
 955        struct blk_trace *bt = q->blk_trace;
 956
 957        if (likely(!bt))
 958                return;
 959
 960        if (rq->cmd_type == REQ_TYPE_BLOCK_PC)
 961                __blk_add_trace(bt, 0, blk_rq_bytes(rq), 0,
 962                                BLK_TA_DRV_DATA, rq->errors, len, data);
 963        else
 964                __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0,
 965                                BLK_TA_DRV_DATA, rq->errors, len, data);
 966}
 967EXPORT_SYMBOL_GPL(blk_add_driver_data);
 968
 969static void blk_register_tracepoints(void)
 970{
 971        int ret;
 972
 973        ret = register_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
 974        WARN_ON(ret);
 975        ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
 976        WARN_ON(ret);
 977        ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
 978        WARN_ON(ret);
 979        ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
 980        WARN_ON(ret);
 981        ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
 982        WARN_ON(ret);
 983        ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
 984        WARN_ON(ret);
 985        ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
 986        WARN_ON(ret);
 987        ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
 988        WARN_ON(ret);
 989        ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
 990        WARN_ON(ret);
 991        ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
 992        WARN_ON(ret);
 993        ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
 994        WARN_ON(ret);
 995        ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
 996        WARN_ON(ret);
 997        ret = register_trace_block_plug(blk_add_trace_plug, NULL);
 998        WARN_ON(ret);
 999        ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1000        WARN_ON(ret);
1001        ret = register_trace_block_split(blk_add_trace_split, NULL);
1002        WARN_ON(ret);
1003        ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1004        WARN_ON(ret);
1005        ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1006        WARN_ON(ret);
1007}
1008
1009static void blk_unregister_tracepoints(void)
1010{
1011        unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1012        unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1013        unregister_trace_block_split(blk_add_trace_split, NULL);
1014        unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1015        unregister_trace_block_plug(blk_add_trace_plug, NULL);
1016        unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1017        unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1018        unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1019        unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1020        unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1021        unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1022        unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1023        unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1024        unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1025        unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1026        unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1027        unregister_trace_block_rq_abort(blk_add_trace_rq_abort, NULL);
1028
1029        tracepoint_synchronize_unregister();
1030}
1031
1032/*
1033 * struct blk_io_tracer formatting routines
1034 */
1035
1036static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1037{
1038        int i = 0;
1039        int tc = t->action >> BLK_TC_SHIFT;
1040
1041        if (t->action == BLK_TN_MESSAGE) {
1042                rwbs[i++] = 'N';
1043                goto out;
1044        }
1045
1046        if (tc & BLK_TC_FLUSH)
1047                rwbs[i++] = 'F';
1048
1049        if (tc & BLK_TC_DISCARD)
1050                rwbs[i++] = 'D';
1051        else if (tc & BLK_TC_WRITE)
1052                rwbs[i++] = 'W';
1053        else if (t->bytes)
1054                rwbs[i++] = 'R';
1055        else
1056                rwbs[i++] = 'N';
1057
1058        if (tc & BLK_TC_FUA)
1059                rwbs[i++] = 'F';
1060        if (tc & BLK_TC_AHEAD)
1061                rwbs[i++] = 'A';
1062        if (tc & BLK_TC_SYNC)
1063                rwbs[i++] = 'S';
1064        if (tc & BLK_TC_META)
1065                rwbs[i++] = 'M';
1066out:
1067        rwbs[i] = '\0';
1068}
1069
1070static inline
1071const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1072{
1073        return (const struct blk_io_trace *)ent;
1074}
1075
1076static inline const void *pdu_start(const struct trace_entry *ent)
1077{
1078        return te_blk_io_trace(ent) + 1;
1079}
1080
1081static inline u32 t_action(const struct trace_entry *ent)
1082{
1083        return te_blk_io_trace(ent)->action;
1084}
1085
1086static inline u32 t_bytes(const struct trace_entry *ent)
1087{
1088        return te_blk_io_trace(ent)->bytes;
1089}
1090
1091static inline u32 t_sec(const struct trace_entry *ent)
1092{
1093        return te_blk_io_trace(ent)->bytes >> 9;
1094}
1095
1096static inline unsigned long long t_sector(const struct trace_entry *ent)
1097{
1098        return te_blk_io_trace(ent)->sector;
1099}
1100
1101static inline __u16 t_error(const struct trace_entry *ent)
1102{
1103        return te_blk_io_trace(ent)->error;
1104}
1105
1106static __u64 get_pdu_int(const struct trace_entry *ent)
1107{
1108        const __u64 *val = pdu_start(ent);
1109        return be64_to_cpu(*val);
1110}
1111
1112static void get_pdu_remap(const struct trace_entry *ent,
1113                          struct blk_io_trace_remap *r)
1114{
1115        const struct blk_io_trace_remap *__r = pdu_start(ent);
1116        __u64 sector_from = __r->sector_from;
1117
1118        r->device_from = be32_to_cpu(__r->device_from);
1119        r->device_to   = be32_to_cpu(__r->device_to);
1120        r->sector_from = be64_to_cpu(sector_from);
1121}
1122
1123typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
1124
1125static int blk_log_action_classic(struct trace_iterator *iter, const char *act)
1126{
1127        char rwbs[RWBS_LEN];
1128        unsigned long long ts  = iter->ts;
1129        unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1130        unsigned secs          = (unsigned long)ts;
1131        const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1132
1133        fill_rwbs(rwbs, t);
1134
1135        return trace_seq_printf(&iter->seq,
1136                                "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1137                                MAJOR(t->device), MINOR(t->device), iter->cpu,
1138                                secs, nsec_rem, iter->ent->pid, act, rwbs);
1139}
1140
1141static int blk_log_action(struct trace_iterator *iter, const char *act)
1142{
1143        char rwbs[RWBS_LEN];
1144        const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1145
1146        fill_rwbs(rwbs, t);
1147        return trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1148                                MAJOR(t->device), MINOR(t->device), act, rwbs);
1149}
1150
1151static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
1152{
1153        const unsigned char *pdu_buf;
1154        int pdu_len;
1155        int i, end, ret;
1156
1157        pdu_buf = pdu_start(ent);
1158        pdu_len = te_blk_io_trace(ent)->pdu_len;
1159
1160        if (!pdu_len)
1161                return 1;
1162
1163        /* find the last zero that needs to be printed */
1164        for (end = pdu_len - 1; end >= 0; end--)
1165                if (pdu_buf[end])
1166                        break;
1167        end++;
1168
1169        if (!trace_seq_putc(s, '('))
1170                return 0;
1171
1172        for (i = 0; i < pdu_len; i++) {
1173
1174                ret = trace_seq_printf(s, "%s%02x",
1175                                       i == 0 ? "" : " ", pdu_buf[i]);
1176                if (!ret)
1177                        return ret;
1178
1179                /*
1180                 * stop when the rest is just zeroes and indicate so
1181                 * with a ".." appended
1182                 */
1183                if (i == end && end != pdu_len - 1)
1184                        return trace_seq_puts(s, " ..) ");
1185        }
1186
1187        return trace_seq_puts(s, ") ");
1188}
1189
1190static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1191{
1192        char cmd[TASK_COMM_LEN];
1193
1194        trace_find_cmdline(ent->pid, cmd);
1195
1196        if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1197                int ret;
1198
1199                ret = trace_seq_printf(s, "%u ", t_bytes(ent));
1200                if (!ret)
1201                        return 0;
1202                ret = blk_log_dump_pdu(s, ent);
1203                if (!ret)
1204                        return 0;
1205                return trace_seq_printf(s, "[%s]\n", cmd);
1206        } else {
1207                if (t_sec(ent))
1208                        return trace_seq_printf(s, "%llu + %u [%s]\n",
1209                                                t_sector(ent), t_sec(ent), cmd);
1210                return trace_seq_printf(s, "[%s]\n", cmd);
1211        }
1212}
1213
1214static int blk_log_with_error(struct trace_seq *s,
1215                              const struct trace_entry *ent)
1216{
1217        if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1218                int ret;
1219
1220                ret = blk_log_dump_pdu(s, ent);
1221                if (ret)
1222                        return trace_seq_printf(s, "[%d]\n", t_error(ent));
1223                return 0;
1224        } else {
1225                if (t_sec(ent))
1226                        return trace_seq_printf(s, "%llu + %u [%d]\n",
1227                                                t_sector(ent),
1228                                                t_sec(ent), t_error(ent));
1229                return trace_seq_printf(s, "%llu [%d]\n",
1230                                        t_sector(ent), t_error(ent));
1231        }
1232}
1233
1234static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1235{
1236        struct blk_io_trace_remap r = { .device_from = 0, };
1237
1238        get_pdu_remap(ent, &r);
1239        return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1240                                t_sector(ent), t_sec(ent),
1241                                MAJOR(r.device_from), MINOR(r.device_from),
1242                                (unsigned long long)r.sector_from);
1243}
1244
1245static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1246{
1247        char cmd[TASK_COMM_LEN];
1248
1249        trace_find_cmdline(ent->pid, cmd);
1250
1251        return trace_seq_printf(s, "[%s]\n", cmd);
1252}
1253
1254static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1255{
1256        char cmd[TASK_COMM_LEN];
1257
1258        trace_find_cmdline(ent->pid, cmd);
1259
1260        return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1261}
1262
1263static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1264{
1265        char cmd[TASK_COMM_LEN];
1266
1267        trace_find_cmdline(ent->pid, cmd);
1268
1269        return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1270                                get_pdu_int(ent), cmd);
1271}
1272
1273static int blk_log_msg(struct trace_seq *s, const struct trace_entry *ent)
1274{
1275        int ret;
1276        const struct blk_io_trace *t = te_blk_io_trace(ent);
1277
1278        ret = trace_seq_putmem(s, t + 1, t->pdu_len);
1279        if (ret)
1280                return trace_seq_putc(s, '\n');
1281        return ret;
1282}
1283
1284/*
1285 * struct tracer operations
1286 */
1287
1288static void blk_tracer_print_header(struct seq_file *m)
1289{
1290        if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1291                return;
1292        seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1293                    "#  |     |     |           |   |   |\n");
1294}
1295
1296static void blk_tracer_start(struct trace_array *tr)
1297{
1298        blk_tracer_enabled = true;
1299}
1300
1301static int blk_tracer_init(struct trace_array *tr)
1302{
1303        blk_tr = tr;
1304        blk_tracer_start(tr);
1305        return 0;
1306}
1307
1308static void blk_tracer_stop(struct trace_array *tr)
1309{
1310        blk_tracer_enabled = false;
1311}
1312
1313static void blk_tracer_reset(struct trace_array *tr)
1314{
1315        blk_tracer_stop(tr);
1316}
1317
1318static const struct {
1319        const char *act[2];
1320        int        (*print)(struct trace_seq *s, const struct trace_entry *ent);
1321} what2act[] = {
1322        [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1323        [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1324        [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1325        [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1326        [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1327        [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1328        [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1329        [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1330        [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1331        [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1332        [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1333        [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1334        [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1335        [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1336        [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1337};
1338
1339static enum print_line_t print_one_line(struct trace_iterator *iter,
1340                                        bool classic)
1341{
1342        struct trace_seq *s = &iter->seq;
1343        const struct blk_io_trace *t;
1344        u16 what;
1345        int ret;
1346        bool long_act;
1347        blk_log_action_t *log_action;
1348
1349        t          = te_blk_io_trace(iter->ent);
1350        what       = t->action & ((1 << BLK_TC_SHIFT) - 1);
1351        long_act   = !!(trace_flags & TRACE_ITER_VERBOSE);
1352        log_action = classic ? &blk_log_action_classic : &blk_log_action;
1353
1354        if (t->action == BLK_TN_MESSAGE) {
1355                ret = log_action(iter, long_act ? "message" : "m");
1356                if (ret)
1357                        ret = blk_log_msg(s, iter->ent);
1358                goto out;
1359        }
1360
1361        if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1362                ret = trace_seq_printf(s, "Unknown action %x\n", what);
1363        else {
1364                ret = log_action(iter, what2act[what].act[long_act]);
1365                if (ret)
1366                        ret = what2act[what].print(s, iter->ent);
1367        }
1368out:
1369        return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1370}
1371
1372static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1373                                               int flags, struct trace_event *event)
1374{
1375        return print_one_line(iter, false);
1376}
1377
1378static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1379{
1380        struct trace_seq *s = &iter->seq;
1381        struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1382        const int offset = offsetof(struct blk_io_trace, sector);
1383        struct blk_io_trace old = {
1384                .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1385                .time     = iter->ts,
1386        };
1387
1388        if (!trace_seq_putmem(s, &old, offset))
1389                return 0;
1390        return trace_seq_putmem(s, &t->sector,
1391                                sizeof(old) - offset + t->pdu_len);
1392}
1393
1394static enum print_line_t
1395blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1396                             struct trace_event *event)
1397{
1398        return blk_trace_synthesize_old_trace(iter) ?
1399                        TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1400}
1401
1402static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1403{
1404        if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1405                return TRACE_TYPE_UNHANDLED;
1406
1407        return print_one_line(iter, true);
1408}
1409
1410static int blk_tracer_set_flag(u32 old_flags, u32 bit, int set)
1411{
1412        /* don't output context-info for blk_classic output */
1413        if (bit == TRACE_BLK_OPT_CLASSIC) {
1414                if (set)
1415                        trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1416                else
1417                        trace_flags |= TRACE_ITER_CONTEXT_INFO;
1418        }
1419        return 0;
1420}
1421
1422static struct tracer blk_tracer __read_mostly = {
1423        .name           = "blk",
1424        .init           = blk_tracer_init,
1425        .reset          = blk_tracer_reset,
1426        .start          = blk_tracer_start,
1427        .stop           = blk_tracer_stop,
1428        .print_header   = blk_tracer_print_header,
1429        .print_line     = blk_tracer_print_line,
1430        .flags          = &blk_tracer_flags,
1431        .set_flag       = blk_tracer_set_flag,
1432};
1433
1434static struct trace_event_functions trace_blk_event_funcs = {
1435        .trace          = blk_trace_event_print,
1436        .binary         = blk_trace_event_print_binary,
1437};
1438
1439static struct trace_event trace_blk_event = {
1440        .type           = TRACE_BLK,
1441        .funcs          = &trace_blk_event_funcs,
1442};
1443
1444static int __init init_blk_tracer(void)
1445{
1446        if (!register_ftrace_event(&trace_blk_event)) {
1447                pr_warning("Warning: could not register block events\n");
1448                return 1;
1449        }
1450
1451        if (register_tracer(&blk_tracer) != 0) {
1452                pr_warning("Warning: could not register the block tracer\n");
1453                unregister_ftrace_event(&trace_blk_event);
1454                return 1;
1455        }
1456
1457        return 0;
1458}
1459
1460device_initcall(init_blk_tracer);
1461
1462static int blk_trace_remove_queue(struct request_queue *q)
1463{
1464        struct blk_trace *bt;
1465
1466        bt = xchg(&q->blk_trace, NULL);
1467        if (bt == NULL)
1468                return -EINVAL;
1469
1470        if (atomic_dec_and_test(&blk_probes_ref))
1471                blk_unregister_tracepoints();
1472
1473        blk_trace_free(bt);
1474        return 0;
1475}
1476
1477/*
1478 * Setup everything required to start tracing
1479 */
1480static int blk_trace_setup_queue(struct request_queue *q,
1481                                 struct block_device *bdev)
1482{
1483        struct blk_trace *old_bt, *bt = NULL;
1484        int ret = -ENOMEM;
1485
1486        bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1487        if (!bt)
1488                return -ENOMEM;
1489
1490        bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1491        if (!bt->msg_data)
1492                goto free_bt;
1493
1494        bt->dev = bdev->bd_dev;
1495        bt->act_mask = (u16)-1;
1496
1497        blk_trace_setup_lba(bt, bdev);
1498
1499        old_bt = xchg(&q->blk_trace, bt);
1500        if (old_bt != NULL) {
1501                (void)xchg(&q->blk_trace, old_bt);
1502                ret = -EBUSY;
1503                goto free_bt;
1504        }
1505
1506        if (atomic_inc_return(&blk_probes_ref) == 1)
1507                blk_register_tracepoints();
1508        return 0;
1509
1510free_bt:
1511        blk_trace_free(bt);
1512        return ret;
1513}
1514
1515/*
1516 * sysfs interface to enable and configure tracing
1517 */
1518
1519static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1520                                         struct device_attribute *attr,
1521                                         char *buf);
1522static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1523                                          struct device_attribute *attr,
1524                                          const char *buf, size_t count);
1525#define BLK_TRACE_DEVICE_ATTR(_name) \
1526        DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1527                    sysfs_blk_trace_attr_show, \
1528                    sysfs_blk_trace_attr_store)
1529
1530static BLK_TRACE_DEVICE_ATTR(enable);
1531static BLK_TRACE_DEVICE_ATTR(act_mask);
1532static BLK_TRACE_DEVICE_ATTR(pid);
1533static BLK_TRACE_DEVICE_ATTR(start_lba);
1534static BLK_TRACE_DEVICE_ATTR(end_lba);
1535
1536static struct attribute *blk_trace_attrs[] = {
1537        &dev_attr_enable.attr,
1538        &dev_attr_act_mask.attr,
1539        &dev_attr_pid.attr,
1540        &dev_attr_start_lba.attr,
1541        &dev_attr_end_lba.attr,
1542        NULL
1543};
1544
1545struct attribute_group blk_trace_attr_group = {
1546        .name  = "trace",
1547        .attrs = blk_trace_attrs,
1548};
1549
1550static const struct {
1551        int mask;
1552        const char *str;
1553} mask_maps[] = {
1554        { BLK_TC_READ,          "read"          },
1555        { BLK_TC_WRITE,         "write"         },
1556        { BLK_TC_FLUSH,         "flush"         },
1557        { BLK_TC_SYNC,          "sync"          },
1558        { BLK_TC_QUEUE,         "queue"         },
1559        { BLK_TC_REQUEUE,       "requeue"       },
1560        { BLK_TC_ISSUE,         "issue"         },
1561        { BLK_TC_COMPLETE,      "complete"      },
1562        { BLK_TC_FS,            "fs"            },
1563        { BLK_TC_PC,            "pc"            },
1564        { BLK_TC_AHEAD,         "ahead"         },
1565        { BLK_TC_META,          "meta"          },
1566        { BLK_TC_DISCARD,       "discard"       },
1567        { BLK_TC_DRV_DATA,      "drv_data"      },
1568        { BLK_TC_FUA,           "fua"           },
1569};
1570
1571static int blk_trace_str2mask(const char *str)
1572{
1573        int i;
1574        int mask = 0;
1575        char *buf, *s, *token;
1576
1577        buf = kstrdup(str, GFP_KERNEL);
1578        if (buf == NULL)
1579                return -ENOMEM;
1580        s = strstrip(buf);
1581
1582        while (1) {
1583                token = strsep(&s, ",");
1584                if (token == NULL)
1585                        break;
1586
1587                if (*token == '\0')
1588                        continue;
1589
1590                for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1591                        if (strcasecmp(token, mask_maps[i].str) == 0) {
1592                                mask |= mask_maps[i].mask;
1593                                break;
1594                        }
1595                }
1596                if (i == ARRAY_SIZE(mask_maps)) {
1597                        mask = -EINVAL;
1598                        break;
1599                }
1600        }
1601        kfree(buf);
1602
1603        return mask;
1604}
1605
1606static ssize_t blk_trace_mask2str(char *buf, int mask)
1607{
1608        int i;
1609        char *p = buf;
1610
1611        for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1612                if (mask & mask_maps[i].mask) {
1613                        p += sprintf(p, "%s%s",
1614                                    (p == buf) ? "" : ",", mask_maps[i].str);
1615                }
1616        }
1617        *p++ = '\n';
1618
1619        return p - buf;
1620}
1621
1622static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1623{
1624        if (bdev->bd_disk == NULL)
1625                return NULL;
1626
1627        return bdev_get_queue(bdev);
1628}
1629
1630static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1631                                         struct device_attribute *attr,
1632                                         char *buf)
1633{
1634        struct hd_struct *p = dev_to_part(dev);
1635        struct request_queue *q;
1636        struct block_device *bdev;
1637        ssize_t ret = -ENXIO;
1638
1639        bdev = bdget(part_devt(p));
1640        if (bdev == NULL)
1641                goto out;
1642
1643        q = blk_trace_get_queue(bdev);
1644        if (q == NULL)
1645                goto out_bdput;
1646
1647        mutex_lock(&bdev->bd_mutex);
1648
1649        if (attr == &dev_attr_enable) {
1650                ret = sprintf(buf, "%u\n", !!q->blk_trace);
1651                goto out_unlock_bdev;
1652        }
1653
1654        if (q->blk_trace == NULL)
1655                ret = sprintf(buf, "disabled\n");
1656        else if (attr == &dev_attr_act_mask)
1657                ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1658        else if (attr == &dev_attr_pid)
1659                ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1660        else if (attr == &dev_attr_start_lba)
1661                ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1662        else if (attr == &dev_attr_end_lba)
1663                ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1664
1665out_unlock_bdev:
1666        mutex_unlock(&bdev->bd_mutex);
1667out_bdput:
1668        bdput(bdev);
1669out:
1670        return ret;
1671}
1672
1673static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1674                                          struct device_attribute *attr,
1675                                          const char *buf, size_t count)
1676{
1677        struct block_device *bdev;
1678        struct request_queue *q;
1679        struct hd_struct *p;
1680        u64 value;
1681        ssize_t ret = -EINVAL;
1682
1683        if (count == 0)
1684                goto out;
1685
1686        if (attr == &dev_attr_act_mask) {
1687                if (sscanf(buf, "%llx", &value) != 1) {
1688                        /* Assume it is a list of trace category names */
1689                        ret = blk_trace_str2mask(buf);
1690                        if (ret < 0)
1691                                goto out;
1692                        value = ret;
1693                }
1694        } else if (sscanf(buf, "%llu", &value) != 1)
1695                goto out;
1696
1697        ret = -ENXIO;
1698
1699        p = dev_to_part(dev);
1700        bdev = bdget(part_devt(p));
1701        if (bdev == NULL)
1702                goto out;
1703
1704        q = blk_trace_get_queue(bdev);
1705        if (q == NULL)
1706                goto out_bdput;
1707
1708        mutex_lock(&bdev->bd_mutex);
1709
1710        if (attr == &dev_attr_enable) {
1711                if (value)
1712                        ret = blk_trace_setup_queue(q, bdev);
1713                else
1714                        ret = blk_trace_remove_queue(q);
1715                goto out_unlock_bdev;
1716        }
1717
1718        ret = 0;
1719        if (q->blk_trace == NULL)
1720                ret = blk_trace_setup_queue(q, bdev);
1721
1722        if (ret == 0) {
1723                if (attr == &dev_attr_act_mask)
1724                        q->blk_trace->act_mask = value;
1725                else if (attr == &dev_attr_pid)
1726                        q->blk_trace->pid = value;
1727                else if (attr == &dev_attr_start_lba)
1728                        q->blk_trace->start_lba = value;
1729                else if (attr == &dev_attr_end_lba)
1730                        q->blk_trace->end_lba = value;
1731        }
1732
1733out_unlock_bdev:
1734        mutex_unlock(&bdev->bd_mutex);
1735out_bdput:
1736        bdput(bdev);
1737out:
1738        return ret ? ret : count;
1739}
1740
1741int blk_trace_init_sysfs(struct device *dev)
1742{
1743        return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1744}
1745
1746void blk_trace_remove_sysfs(struct device *dev)
1747{
1748        sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1749}
1750
1751#endif /* CONFIG_BLK_DEV_IO_TRACE */
1752
1753#ifdef CONFIG_EVENT_TRACING
1754
1755void blk_dump_cmd(char *buf, struct request *rq)
1756{
1757        int i, end;
1758        int len = rq->cmd_len;
1759        unsigned char *cmd = rq->cmd;
1760
1761        if (rq->cmd_type != REQ_TYPE_BLOCK_PC) {
1762                buf[0] = '\0';
1763                return;
1764        }
1765
1766        for (end = len - 1; end >= 0; end--)
1767                if (cmd[end])
1768                        break;
1769        end++;
1770
1771        for (i = 0; i < len; i++) {
1772                buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
1773                if (i == end && end != len - 1) {
1774                        sprintf(buf, " ..");
1775                        break;
1776                }
1777        }
1778}
1779
1780void blk_fill_rwbs(char *rwbs, u32 rw, int bytes)
1781{
1782        int i = 0;
1783
1784        if (rw & REQ_FLUSH)
1785                rwbs[i++] = 'F';
1786
1787        if (rw & WRITE)
1788                rwbs[i++] = 'W';
1789        else if (rw & REQ_DISCARD)
1790                rwbs[i++] = 'D';
1791        else if (bytes)
1792                rwbs[i++] = 'R';
1793        else
1794                rwbs[i++] = 'N';
1795
1796        if (rw & REQ_FUA)
1797                rwbs[i++] = 'F';
1798        if (rw & REQ_RAHEAD)
1799                rwbs[i++] = 'A';
1800        if (rw & REQ_SYNC)
1801                rwbs[i++] = 'S';
1802        if (rw & REQ_META)
1803                rwbs[i++] = 'M';
1804        if (rw & REQ_SECURE)
1805                rwbs[i++] = 'E';
1806
1807        rwbs[i] = '\0';
1808}
1809
1810#endif /* CONFIG_EVENT_TRACING */
1811
1812
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