kernel/trace/blktrace.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
   4  *
   5  */
   6
   7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   8
   9 #include <linux/kernel.h>
  10 #include <linux/blkdev.h>
  11 #include <linux/blktrace_api.h>
  12 #include <linux/percpu.h>
  13 #include <linux/init.h>
  14 #include <linux/mutex.h>
  15 #include <linux/slab.h>
  16 #include <linux/debugfs.h>
  17 #include <linux/export.h>
  18 #include <linux/time.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/list.h>
  21 #include <linux/blk-cgroup.h>
  22
  23 #include "../../block/blk.h"
  24
  25 #include <trace/events/block.h>
  26
  27 #include "trace_output.h"
  28
  29 #ifdef CONFIG_BLK_DEV_IO_TRACE
  30
  31 static unsigned int blktrace_seq __read_mostly = 1;
  32
  33 static struct trace_array *blk_tr;
  34 static bool blk_tracer_enabled __read_mostly;
  35
  36 static LIST_HEAD(running_trace_list);
  37 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock);
  38
  39 /* Select an alternative, minimalistic output than the original one */
  40 #define TRACE_BLK_OPT_CLASSIC   0x1
  41 #define TRACE_BLK_OPT_CGROUP    0x2
  42 #define TRACE_BLK_OPT_CGNAME    0x4
  43
  44 static struct tracer_opt blk_tracer_opts[] = {
  45         /* Default disable the minimalistic output */
  46         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
  47 #ifdef CONFIG_BLK_CGROUP
  48         { TRACER_OPT(blk_cgroup, TRACE_BLK_OPT_CGROUP) },
  49         { TRACER_OPT(blk_cgname, TRACE_BLK_OPT_CGNAME) },
  50 #endif
  51         { }
  52 };
  53
  54 static struct tracer_flags blk_tracer_flags = {
  55         .val  = 0,
  56         .opts = blk_tracer_opts,
  57 };
  58
  59 /* Global reference count of probes */
  60 static DEFINE_MUTEX(blk_probe_mutex);
  61 static int blk_probes_ref;
  62
  63 static void blk_register_tracepoints(void);
  64 static void blk_unregister_tracepoints(void);
  65
  66 /*
  67  * Send out a notify message.
  68  */
  69 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
  70                        const void *data, size_t len, u64 cgid)
  71 {
  72         struct blk_io_trace *t;
  73         struct ring_buffer_event *event = NULL;
  74         struct trace_buffer *buffer = NULL;
  75         int pc = 0;
  76         int cpu = smp_processor_id();
  77         bool blk_tracer = blk_tracer_enabled;
  78         ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
  79
  80         if (blk_tracer) {
  81                 buffer = blk_tr->array_buffer.buffer;
  82                 pc = preempt_count();
  83                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
  84                                                   sizeof(*t) + len + cgid_len,
  85                                                   0, pc);
  86                 if (!event)
  87                         return;
  88                 t = ring_buffer_event_data(event);
  89                 goto record_it;
  90         }
  91
  92         if (!bt->rchan)
  93                 return;
  94
  95         t = relay_reserve(bt->rchan, sizeof(*t) + len + cgid_len);
  96         if (t) {
  97                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
  98                 t->time = ktime_to_ns(ktime_get());
  99 record_it:
 100                 t->device = bt->dev;
 101                 t->action = action | (cgid ? __BLK_TN_CGROUP : 0);
 102                 t->pid = pid;
 103                 t->cpu = cpu;
 104                 t->pdu_len = len + cgid_len;
 105                 if (cgid_len)
 106                         memcpy((void *)t + sizeof(*t), &cgid, cgid_len);
 107                 memcpy((void *) t + sizeof(*t) + cgid_len, data, len);
 108
 109                 if (blk_tracer)
 110                         trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
 111         }
 112 }
 113
 114 /*
 115  * Send out a notify for this process, if we haven't done so since a trace
 116  * started
 117  */
 118 static void trace_note_tsk(struct task_struct *tsk)
 119 {
 120         unsigned long flags;
 121         struct blk_trace *bt;
 122
 123         tsk->btrace_seq = blktrace_seq;
 124         spin_lock_irqsave(&running_trace_lock, flags);
 125         list_for_each_entry(bt, &running_trace_list, running_list) {
 126                 trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm,
 127                            sizeof(tsk->comm), 0);
 128         }
 129         spin_unlock_irqrestore(&running_trace_lock, flags);
 130 }
 131
 132 static void trace_note_time(struct blk_trace *bt)
 133 {
 134         struct timespec64 now;
 135         unsigned long flags;
 136         u32 words[2];
 137
 138         /* need to check user space to see if this breaks in y2038 or y2106 */
 139         ktime_get_real_ts64(&now);
 140         words[0] = (u32)now.tv_sec;
 141         words[1] = now.tv_nsec;
 142
 143         local_irq_save(flags);
 144         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words), 0);
 145         local_irq_restore(flags);
 146 }
 147
 148 void __trace_note_message(struct blk_trace *bt, struct blkcg *blkcg,
 149         const char *fmt, ...)
 150 {
 151         int n;
 152         va_list args;
 153         unsigned long flags;
 154         char *buf;
 155
 156         if (unlikely(bt->trace_state != Blktrace_running &&
 157                      !blk_tracer_enabled))
 158                 return;
 159
 160         /*
 161          * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
 162          * message to the trace.
 163          */
 164         if (!(bt->act_mask & BLK_TC_NOTIFY))
 165                 return;
 166
 167         local_irq_save(flags);
 168         buf = this_cpu_ptr(bt->msg_data);
 169         va_start(args, fmt);
 170         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 171         va_end(args);
 172
 173         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
 174                 blkcg = NULL;
 175 #ifdef CONFIG_BLK_CGROUP
 176         trace_note(bt, current->pid, BLK_TN_MESSAGE, buf, n,
 177                    blkcg ? cgroup_id(blkcg->css.cgroup) : 1);
 178 #else
 179         trace_note(bt, current->pid, BLK_TN_MESSAGE, buf, n, 0);
 180 #endif
 181         local_irq_restore(flags);
 182 }
 183 EXPORT_SYMBOL_GPL(__trace_note_message);
 184
 185 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
 186                          pid_t pid)
 187 {
 188         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
 189                 return 1;
 190         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
 191                 return 1;
 192         if (bt->pid && pid != bt->pid)
 193                 return 1;
 194
 195         return 0;
 196 }
 197
 198 /*
 199  * Data direction bit lookup
 200  */
 201 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
 202                                  BLK_TC_ACT(BLK_TC_WRITE) };
 203
 204 #define BLK_TC_RAHEAD           BLK_TC_AHEAD
 205 #define BLK_TC_PREFLUSH         BLK_TC_FLUSH
 206
 207 /* The ilog2() calls fall out because they're constant */
 208 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
 209           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
 210
 211 /*
 212  * The worker for the various blk_add_trace*() types. Fills out a
 213  * blk_io_trace structure and places it in a per-cpu subbuffer.
 214  */
 215 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 216                      int op, int op_flags, u32 what, int error, int pdu_len,
 217                      void *pdu_data, u64 cgid)
 218 {
 219         struct task_struct *tsk = current;
 220         struct ring_buffer_event *event = NULL;
 221         struct trace_buffer *buffer = NULL;
 222         struct blk_io_trace *t;
 223         unsigned long flags = 0;
 224         unsigned long *sequence;
 225         pid_t pid;
 226         int cpu, pc = 0;
 227         bool blk_tracer = blk_tracer_enabled;
 228         ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
 229
 230         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
 231                 return;
 232
 233         what |= ddir_act[op_is_write(op) ? WRITE : READ];
 234         what |= MASK_TC_BIT(op_flags, SYNC);
 235         what |= MASK_TC_BIT(op_flags, RAHEAD);
 236         what |= MASK_TC_BIT(op_flags, META);
 237         what |= MASK_TC_BIT(op_flags, PREFLUSH);
 238         what |= MASK_TC_BIT(op_flags, FUA);
 239         if (op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE)
 240                 what |= BLK_TC_ACT(BLK_TC_DISCARD);
 241         if (op == REQ_OP_FLUSH)
 242                 what |= BLK_TC_ACT(BLK_TC_FLUSH);
 243         if (cgid)
 244                 what |= __BLK_TA_CGROUP;
 245
 246         pid = tsk->pid;
 247         if (act_log_check(bt, what, sector, pid))
 248                 return;
 249         cpu = raw_smp_processor_id();
 250
 251         if (blk_tracer) {
 252                 tracing_record_cmdline(current);
 253
 254                 buffer = blk_tr->array_buffer.buffer;
 255                 pc = preempt_count();
 256                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 257                                                   sizeof(*t) + pdu_len + cgid_len,
 258                                                   0, pc);
 259                 if (!event)
 260                         return;
 261                 t = ring_buffer_event_data(event);
 262                 goto record_it;
 263         }
 264
 265         if (unlikely(tsk->btrace_seq != blktrace_seq))
 266                 trace_note_tsk(tsk);
 267
 268         /*
 269          * A word about the locking here - we disable interrupts to reserve
 270          * some space in the relay per-cpu buffer, to prevent an irq
 271          * from coming in and stepping on our toes.
 272          */
 273         local_irq_save(flags);
 274         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len + cgid_len);
 275         if (t) {
 276                 sequence = per_cpu_ptr(bt->sequence, cpu);
 277
 278                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 279                 t->sequence = ++(*sequence);
 280                 t->time = ktime_to_ns(ktime_get());
 281 record_it:
 282                 /*
 283                  * These two are not needed in ftrace as they are in the
 284                  * generic trace_entry, filled by tracing_generic_entry_update,
 285                  * but for the trace_event->bin() synthesizer benefit we do it
 286                  * here too.
 287                  */
 288                 t->cpu = cpu;
 289                 t->pid = pid;
 290
 291                 t->sector = sector;
 292                 t->bytes = bytes;
 293                 t->action = what;
 294                 t->device = bt->dev;
 295                 t->error = error;
 296                 t->pdu_len = pdu_len + cgid_len;
 297
 298                 if (cgid_len)
 299                         memcpy((void *)t + sizeof(*t), &cgid, cgid_len);
 300                 if (pdu_len)
 301                         memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len);
 302
 303                 if (blk_tracer) {
 304                         trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
 305                         return;
 306                 }
 307         }
 308
 309         local_irq_restore(flags);
 310 }
 311
 312 static void blk_trace_free(struct blk_trace *bt)
 313 {
 314         debugfs_remove(bt->msg_file);
 315         debugfs_remove(bt->dropped_file);
 316         relay_close(bt->rchan);
 317         debugfs_remove(bt->dir);
 318         free_percpu(bt->sequence);
 319         free_percpu(bt->msg_data);
 320         kfree(bt);
 321 }
 322
 323 static void get_probe_ref(void)
 324 {
 325         mutex_lock(&blk_probe_mutex);
 326         if (++blk_probes_ref == 1)
 327                 blk_register_tracepoints();
 328         mutex_unlock(&blk_probe_mutex);
 329 }
 330
 331 static void put_probe_ref(void)
 332 {
 333         mutex_lock(&blk_probe_mutex);
 334         if (!--blk_probes_ref)
 335                 blk_unregister_tracepoints();
 336         mutex_unlock(&blk_probe_mutex);
 337 }
 338
 339 static void blk_trace_cleanup(struct blk_trace *bt)
 340 {
 341         synchronize_rcu();
 342         blk_trace_free(bt);
 343         put_probe_ref();
 344 }
 345
 346 static int __blk_trace_remove(struct request_queue *q)
 347 {
 348         struct blk_trace *bt;
 349
 350         bt = rcu_replace_pointer(q->blk_trace, NULL,
 351                                  lockdep_is_held(&q->blk_trace_mutex));
 352         if (!bt)
 353                 return -EINVAL;
 354
 355         if (bt->trace_state != Blktrace_running)
 356                 blk_trace_cleanup(bt);
 357
 358         return 0;
 359 }
 360
 361 int blk_trace_remove(struct request_queue *q)
 362 {
 363         int ret;
 364
 365         mutex_lock(&q->blk_trace_mutex);
 366         ret = __blk_trace_remove(q);
 367         mutex_unlock(&q->blk_trace_mutex);
 368
 369         return ret;
 370 }
 371 EXPORT_SYMBOL_GPL(blk_trace_remove);
 372
 373 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
 374                                 size_t count, loff_t *ppos)
 375 {
 376         struct blk_trace *bt = filp->private_data;
 377         char buf[16];
 378
 379         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
 380
 381         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 382 }
 383
 384 static const struct file_operations blk_dropped_fops = {
 385         .owner =        THIS_MODULE,
 386         .open =         simple_open,
 387         .read =         blk_dropped_read,
 388         .llseek =       default_llseek,
 389 };
 390
 391 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 392                                 size_t count, loff_t *ppos)
 393 {
 394         char *msg;
 395         struct blk_trace *bt;
 396
 397         if (count >= BLK_TN_MAX_MSG)
 398                 return -EINVAL;
 399
 400         msg = memdup_user_nul(buffer, count);
 401         if (IS_ERR(msg))
 402                 return PTR_ERR(msg);
 403
 404         bt = filp->private_data;
 405         __trace_note_message(bt, NULL, "%s", msg);
 406         kfree(msg);
 407
 408         return count;
 409 }
 410
 411 static const struct file_operations blk_msg_fops = {
 412         .owner =        THIS_MODULE,
 413         .open =         simple_open,
 414         .write =        blk_msg_write,
 415         .llseek =       noop_llseek,
 416 };
 417
 418 /*
 419  * Keep track of how many times we encountered a full subbuffer, to aid
 420  * the user space app in telling how many lost events there were.
 421  */
 422 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
 423                                      void *prev_subbuf, size_t prev_padding)
 424 {
 425         struct blk_trace *bt;
 426
 427         if (!relay_buf_full(buf))
 428                 return 1;
 429
 430         bt = buf->chan->private_data;
 431         atomic_inc(&bt->dropped);
 432         return 0;
 433 }
 434
 435 static int blk_remove_buf_file_callback(struct dentry *dentry)
 436 {
 437         debugfs_remove(dentry);
 438
 439         return 0;
 440 }
 441
 442 static struct dentry *blk_create_buf_file_callback(const char *filename,
 443                                                    struct dentry *parent,
 444                                                    umode_t mode,
 445                                                    struct rchan_buf *buf,
 446                                                    int *is_global)
 447 {
 448         return debugfs_create_file(filename, mode, parent, buf,
 449                                         &relay_file_operations);
 450 }
 451
 452 static struct rchan_callbacks blk_relay_callbacks = {
 453         .subbuf_start           = blk_subbuf_start_callback,
 454         .create_buf_file        = blk_create_buf_file_callback,
 455         .remove_buf_file        = blk_remove_buf_file_callback,
 456 };
 457
 458 static void blk_trace_setup_lba(struct blk_trace *bt,
 459                                 struct block_device *bdev)
 460 {
 461         struct hd_struct *part = NULL;
 462
 463         if (bdev)
 464                 part = bdev->bd_part;
 465
 466         if (part) {
 467                 bt->start_lba = part->start_sect;
 468                 bt->end_lba = part->start_sect + part->nr_sects;
 469         } else {
 470                 bt->start_lba = 0;
 471                 bt->end_lba = -1ULL;
 472         }
 473 }
 474
 475 /*
 476  * Setup everything required to start tracing
 477  */
 478 static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 479                               struct block_device *bdev,
 480                               struct blk_user_trace_setup *buts)
 481 {
 482         struct blk_trace *bt = NULL;
 483         struct dentry *dir = NULL;
 484         int ret;
 485
 486         if (!buts->buf_size || !buts->buf_nr)
 487                 return -EINVAL;
 488
 489         if (!blk_debugfs_root)
 490                 return -ENOENT;
 491
 492         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 493         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 494
 495         /*
 496          * some device names have larger paths - convert the slashes
 497          * to underscores for this to work as expected
 498          */
 499         strreplace(buts->name, '/', '_');
 500
 501         /*
 502          * bdev can be NULL, as with scsi-generic, this is a helpful as
 503          * we can be.
 504          */
 505         if (rcu_dereference_protected(q->blk_trace,
 506                                       lockdep_is_held(&q->blk_trace_mutex))) {
 507                 pr_warn("Concurrent blktraces are not allowed on %s\n",
 508                         buts->name);
 509                 return -EBUSY;
 510         }
 511
 512         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 513         if (!bt)
 514                 return -ENOMEM;
 515
 516         ret = -ENOMEM;
 517         bt->sequence = alloc_percpu(unsigned long);
 518         if (!bt->sequence)
 519                 goto err;
 520
 521         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 522         if (!bt->msg_data)
 523                 goto err;
 524
 525         ret = -ENOENT;
 526
 527         dir = debugfs_lookup(buts->name, blk_debugfs_root);
 528         if (!dir)
 529                 bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);
 530
 531         bt->dev = dev;
 532         atomic_set(&bt->dropped, 0);
 533         INIT_LIST_HEAD(&bt->running_list);
 534
 535         ret = -EIO;
 536         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 537                                                &blk_dropped_fops);
 538
 539         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 540
 541         bt->rchan = relay_open("trace", dir, buts->buf_size,
 542                                 buts->buf_nr, &blk_relay_callbacks, bt);
 543         if (!bt->rchan)
 544                 goto err;
 545
 546         bt->act_mask = buts->act_mask;
 547         if (!bt->act_mask)
 548                 bt->act_mask = (u16) -1;
 549
 550         blk_trace_setup_lba(bt, bdev);
 551
 552         /* overwrite with user settings */
 553         if (buts->start_lba)
 554                 bt->start_lba = buts->start_lba;
 555         if (buts->end_lba)
 556                 bt->end_lba = buts->end_lba;
 557
 558         bt->pid = buts->pid;
 559         bt->trace_state = Blktrace_setup;
 560
 561         rcu_assign_pointer(q->blk_trace, bt);
 562         get_probe_ref();
 563
 564         ret = 0;
 565 err:
 566         if (dir && !bt->dir)
 567                 dput(dir);
 568         if (ret)
 569                 blk_trace_free(bt);
 570         return ret;
 571 }
 572
 573 static int __blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 574                              struct block_device *bdev, char __user *arg)
 575 {
 576         struct blk_user_trace_setup buts;
 577         int ret;
 578
 579         ret = copy_from_user(&buts, arg, sizeof(buts));
 580         if (ret)
 581                 return -EFAULT;
 582
 583         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 584         if (ret)
 585                 return ret;
 586
 587         if (copy_to_user(arg, &buts, sizeof(buts))) {
 588                 __blk_trace_remove(q);
 589                 return -EFAULT;
 590         }
 591         return 0;
 592 }
 593
 594 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 595                     struct block_device *bdev,
 596                     char __user *arg)
 597 {
 598         int ret;
 599
 600         mutex_lock(&q->blk_trace_mutex);
 601         ret = __blk_trace_setup(q, name, dev, bdev, arg);
 602         mutex_unlock(&q->blk_trace_mutex);
 603
 604         return ret;
 605 }
 606 EXPORT_SYMBOL_GPL(blk_trace_setup);
 607
 608 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 609 static int compat_blk_trace_setup(struct request_queue *q, char *name,
 610                                   dev_t dev, struct block_device *bdev,
 611                                   char __user *arg)
 612 {
 613         struct blk_user_trace_setup buts;
 614         struct compat_blk_user_trace_setup cbuts;
 615         int ret;
 616
 617         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
 618                 return -EFAULT;
 619
 620         buts = (struct blk_user_trace_setup) {
 621                 .act_mask = cbuts.act_mask,
 622                 .buf_size = cbuts.buf_size,
 623                 .buf_nr = cbuts.buf_nr,
 624                 .start_lba = cbuts.start_lba,
 625                 .end_lba = cbuts.end_lba,
 626                 .pid = cbuts.pid,
 627         };
 628
 629         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 630         if (ret)
 631                 return ret;
 632
 633         if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
 634                 __blk_trace_remove(q);
 635                 return -EFAULT;
 636         }
 637
 638         return 0;
 639 }
 640 #endif
 641
 642 static int __blk_trace_startstop(struct request_queue *q, int start)
 643 {
 644         int ret;
 645         struct blk_trace *bt;
 646
 647         bt = rcu_dereference_protected(q->blk_trace,
 648                                        lockdep_is_held(&q->blk_trace_mutex));
 649         if (bt == NULL)
 650                 return -EINVAL;
 651
 652         /*
 653          * For starting a trace, we can transition from a setup or stopped
 654          * trace. For stopping a trace, the state must be running
 655          */
 656         ret = -EINVAL;
 657         if (start) {
 658                 if (bt->trace_state == Blktrace_setup ||
 659                     bt->trace_state == Blktrace_stopped) {
 660                         blktrace_seq++;
 661                         smp_mb();
 662                         bt->trace_state = Blktrace_running;
 663                         spin_lock_irq(&running_trace_lock);
 664                         list_add(&bt->running_list, &running_trace_list);
 665                         spin_unlock_irq(&running_trace_lock);
 666
 667                         trace_note_time(bt);
 668                         ret = 0;
 669                 }
 670         } else {
 671                 if (bt->trace_state == Blktrace_running) {
 672                         bt->trace_state = Blktrace_stopped;
 673                         spin_lock_irq(&running_trace_lock);
 674                         list_del_init(&bt->running_list);
 675                         spin_unlock_irq(&running_trace_lock);
 676                         relay_flush(bt->rchan);
 677                         ret = 0;
 678                 }
 679         }
 680
 681         return ret;
 682 }
 683
 684 int blk_trace_startstop(struct request_queue *q, int start)
 685 {
 686         int ret;
 687
 688         mutex_lock(&q->blk_trace_mutex);
 689         ret = __blk_trace_startstop(q, start);
 690         mutex_unlock(&q->blk_trace_mutex);
 691
 692         return ret;
 693 }
 694 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 695
 696 /*
 697  * When reading or writing the blktrace sysfs files, the references to the
 698  * opened sysfs or device files should prevent the underlying block device
 699  * from being removed. So no further delete protection is really needed.
 700  */
 701
 702 /**
 703  * blk_trace_ioctl: - handle the ioctls associated with tracing
 704  * @bdev:       the block device
 705  * @cmd:        the ioctl cmd
 706  * @arg:        the argument data, if any
 707  *
 708  **/
 709 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 710 {
 711         struct request_queue *q;
 712         int ret, start = 0;
 713         char b[BDEVNAME_SIZE];
 714
 715         q = bdev_get_queue(bdev);
 716         if (!q)
 717                 return -ENXIO;
 718
 719         mutex_lock(&q->blk_trace_mutex);
 720
 721         switch (cmd) {
 722         case BLKTRACESETUP:
 723                 bdevname(bdev, b);
 724                 ret = __blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 725                 break;
 726 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 727         case BLKTRACESETUP32:
 728                 bdevname(bdev, b);
 729                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 730                 break;
 731 #endif
 732         case BLKTRACESTART:
 733                 start = 1;
 734                 /* fall through */
 735         case BLKTRACESTOP:
 736                 ret = __blk_trace_startstop(q, start);
 737                 break;
 738         case BLKTRACETEARDOWN:
 739                 ret = __blk_trace_remove(q);
 740                 break;
 741         default:
 742                 ret = -ENOTTY;
 743                 break;
 744         }
 745
 746         mutex_unlock(&q->blk_trace_mutex);
 747         return ret;
 748 }
 749
 750 /**
 751  * blk_trace_shutdown: - stop and cleanup trace structures
 752  * @q:    the request queue associated with the device
 753  *
 754  **/
 755 void blk_trace_shutdown(struct request_queue *q)
 756 {
 757         mutex_lock(&q->blk_trace_mutex);
 758         if (rcu_dereference_protected(q->blk_trace,
 759                                       lockdep_is_held(&q->blk_trace_mutex))) {
 760                 __blk_trace_startstop(q, 0);
 761                 __blk_trace_remove(q);
 762         }
 763
 764         mutex_unlock(&q->blk_trace_mutex);
 765 }
 766
 767 #ifdef CONFIG_BLK_CGROUP
 768 static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 769 {
 770         struct blk_trace *bt;
 771
 772         /* We don't use the 'bt' value here except as an optimization... */
 773         bt = rcu_dereference_protected(q->blk_trace, 1);
 774         if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
 775                 return 0;
 776
 777         if (!bio->bi_blkg)
 778                 return 0;
 779         return cgroup_id(bio_blkcg(bio)->css.cgroup);
 780 }
 781 #else
 782 u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 783 {
 784         return 0;
 785 }
 786 #endif
 787
 788 static u64
 789 blk_trace_request_get_cgid(struct request_queue *q, struct request *rq)
 790 {
 791         if (!rq->bio)
 792                 return 0;
 793         /* Use the first bio */
 794         return blk_trace_bio_get_cgid(q, rq->bio);
 795 }
 796
 797 /*
 798  * blktrace probes
 799  */
 800
 801 /**
 802  * blk_add_trace_rq - Add a trace for a request oriented action
 803  * @rq:         the source request
 804  * @error:      return status to log
 805  * @nr_bytes:   number of completed bytes
 806  * @what:       the action
 807  * @cgid:       the cgroup info
 808  *
 809  * Description:
 810  *     Records an action against a request. Will log the bio offset + size.
 811  *
 812  **/
 813 static void blk_add_trace_rq(struct request *rq, int error,
 814                              unsigned int nr_bytes, u32 what, u64 cgid)
 815 {
 816         struct blk_trace *bt;
 817
 818         rcu_read_lock();
 819         bt = rcu_dereference(rq->q->blk_trace);
 820         if (likely(!bt)) {
 821                 rcu_read_unlock();
 822                 return;
 823         }
 824
 825         if (blk_rq_is_passthrough(rq))
 826                 what |= BLK_TC_ACT(BLK_TC_PC);
 827         else
 828                 what |= BLK_TC_ACT(BLK_TC_FS);
 829
 830         __blk_add_trace(bt, blk_rq_trace_sector(rq), nr_bytes, req_op(rq),
 831                         rq->cmd_flags, what, error, 0, NULL, cgid);
 832         rcu_read_unlock();
 833 }
 834
 835 static void blk_add_trace_rq_insert(void *ignore,
 836                                     struct request_queue *q, struct request *rq)
 837 {
 838         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_INSERT,
 839                          blk_trace_request_get_cgid(q, rq));
 840 }
 841
 842 static void blk_add_trace_rq_issue(void *ignore,
 843                                    struct request_queue *q, struct request *rq)
 844 {
 845         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_ISSUE,
 846                          blk_trace_request_get_cgid(q, rq));
 847 }
 848
 849 static void blk_add_trace_rq_requeue(void *ignore,
 850                                      struct request_queue *q,
 851                                      struct request *rq)
 852 {
 853         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_REQUEUE,
 854                          blk_trace_request_get_cgid(q, rq));
 855 }
 856
 857 static void blk_add_trace_rq_complete(void *ignore, struct request *rq,
 858                         int error, unsigned int nr_bytes)
 859 {
 860         blk_add_trace_rq(rq, error, nr_bytes, BLK_TA_COMPLETE,
 861                          blk_trace_request_get_cgid(rq->q, rq));
 862 }
 863
 864 /**
 865  * blk_add_trace_bio - Add a trace for a bio oriented action
 866  * @q:          queue the io is for
 867  * @bio:        the source bio
 868  * @what:       the action
 869  * @error:      error, if any
 870  *
 871  * Description:
 872  *     Records an action against a bio. Will log the bio offset + size.
 873  *
 874  **/
 875 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 876                               u32 what, int error)
 877 {
 878         struct blk_trace *bt;
 879
 880         rcu_read_lock();
 881         bt = rcu_dereference(q->blk_trace);
 882         if (likely(!bt)) {
 883                 rcu_read_unlock();
 884                 return;
 885         }
 886
 887         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
 888                         bio_op(bio), bio->bi_opf, what, error, 0, NULL,
 889                         blk_trace_bio_get_cgid(q, bio));
 890         rcu_read_unlock();
 891 }
 892
 893 static void blk_add_trace_bio_bounce(void *ignore,
 894                                      struct request_queue *q, struct bio *bio)
 895 {
 896         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
 897 }
 898
 899 static void blk_add_trace_bio_complete(void *ignore,
 900                                        struct request_queue *q, struct bio *bio)
 901 {
 902         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE,
 903                           blk_status_to_errno(bio->bi_status));
 904 }
 905
 906 static void blk_add_trace_bio_backmerge(void *ignore,
 907                                         struct request_queue *q,
 908                                         struct request *rq,
 909                                         struct bio *bio)
 910 {
 911         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
 912 }
 913
 914 static void blk_add_trace_bio_frontmerge(void *ignore,
 915                                          struct request_queue *q,
 916                                          struct request *rq,
 917                                          struct bio *bio)
 918 {
 919         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
 920 }
 921
 922 static void blk_add_trace_bio_queue(void *ignore,
 923                                     struct request_queue *q, struct bio *bio)
 924 {
 925         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
 926 }
 927
 928 static void blk_add_trace_getrq(void *ignore,
 929                                 struct request_queue *q,
 930                                 struct bio *bio, int rw)
 931 {
 932         if (bio)
 933                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
 934         else {
 935                 struct blk_trace *bt;
 936
 937                 rcu_read_lock();
 938                 bt = rcu_dereference(q->blk_trace);
 939                 if (bt)
 940                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_GETRQ, 0, 0,
 941                                         NULL, 0);
 942                 rcu_read_unlock();
 943         }
 944 }
 945
 946
 947 static void blk_add_trace_sleeprq(void *ignore,
 948                                   struct request_queue *q,
 949                                   struct bio *bio, int rw)
 950 {
 951         if (bio)
 952                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
 953         else {
 954                 struct blk_trace *bt;
 955
 956                 rcu_read_lock();
 957                 bt = rcu_dereference(q->blk_trace);
 958                 if (bt)
 959                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_SLEEPRQ,
 960                                         0, 0, NULL, 0);
 961                 rcu_read_unlock();
 962         }
 963 }
 964
 965 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 966 {
 967         struct blk_trace *bt;
 968
 969         rcu_read_lock();
 970         bt = rcu_dereference(q->blk_trace);
 971         if (bt)
 972                 __blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL, 0);
 973         rcu_read_unlock();
 974 }
 975
 976 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 977                                     unsigned int depth, bool explicit)
 978 {
 979         struct blk_trace *bt;
 980
 981         rcu_read_lock();
 982         bt = rcu_dereference(q->blk_trace);
 983         if (bt) {
 984                 __be64 rpdu = cpu_to_be64(depth);
 985                 u32 what;
 986
 987                 if (explicit)
 988                         what = BLK_TA_UNPLUG_IO;
 989                 else
 990                         what = BLK_TA_UNPLUG_TIMER;
 991
 992                 __blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu, 0);
 993         }
 994         rcu_read_unlock();
 995 }
 996
 997 static void blk_add_trace_split(void *ignore,
 998                                 struct request_queue *q, struct bio *bio,
 999                                 unsigned int pdu)
1000 {
1001         struct blk_trace *bt;
1002
1003         rcu_read_lock();
1004         bt = rcu_dereference(q->blk_trace);
1005         if (bt) {
1006                 __be64 rpdu = cpu_to_be64(pdu);
1007
1008                 __blk_add_trace(bt, bio->bi_iter.bi_sector,
1009                                 bio->bi_iter.bi_size, bio_op(bio), bio->bi_opf,
1010                                 BLK_TA_SPLIT,
1011                                 blk_status_to_errno(bio->bi_status),
1012                                 sizeof(rpdu), &rpdu,
1013                                 blk_trace_bio_get_cgid(q, bio));
1014         }
1015         rcu_read_unlock();
1016 }
1017
1018 /**
1019  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
1020  * @ignore:     trace callback data parameter (not used)
1021  * @q:          queue the io is for
1022  * @bio:        the source bio
1023  * @dev:        target device
1024  * @from:       source sector
1025  *
1026  * Description:
1027  *     Device mapper or raid target sometimes need to split a bio because
1028  *     it spans a stripe (or similar). Add a trace for that action.
1029  *
1030  **/
1031 static void blk_add_trace_bio_remap(void *ignore,
1032                                     struct request_queue *q, struct bio *bio,
1033                                     dev_t dev, sector_t from)
1034 {
1035         struct blk_trace *bt;
1036         struct blk_io_trace_remap r;
1037
1038         rcu_read_lock();
1039         bt = rcu_dereference(q->blk_trace);
1040         if (likely(!bt)) {
1041                 rcu_read_unlock();
1042                 return;
1043         }
1044
1045         r.device_from = cpu_to_be32(dev);
1046         r.device_to   = cpu_to_be32(bio_dev(bio));
1047         r.sector_from = cpu_to_be64(from);
1048
1049         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
1050                         bio_op(bio), bio->bi_opf, BLK_TA_REMAP,
1051                         blk_status_to_errno(bio->bi_status),
1052                         sizeof(r), &r, blk_trace_bio_get_cgid(q, bio));
1053         rcu_read_unlock();
1054 }
1055
1056 /**
1057  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
1058  * @ignore:     trace callback data parameter (not used)
1059  * @q:          queue the io is for
1060  * @rq:         the source request
1061  * @dev:        target device
1062  * @from:       source sector
1063  *
1064  * Description:
1065  *     Device mapper remaps request to other devices.
1066  *     Add a trace for that action.
1067  *
1068  **/
1069 static void blk_add_trace_rq_remap(void *ignore,
1070                                    struct request_queue *q,
1071                                    struct request *rq, dev_t dev,
1072                                    sector_t from)
1073 {
1074         struct blk_trace *bt;
1075         struct blk_io_trace_remap r;
1076
1077         rcu_read_lock();
1078         bt = rcu_dereference(q->blk_trace);
1079         if (likely(!bt)) {
1080                 rcu_read_unlock();
1081                 return;
1082         }
1083
1084         r.device_from = cpu_to_be32(dev);
1085         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
1086         r.sector_from = cpu_to_be64(from);
1087
1088         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
1089                         rq_data_dir(rq), 0, BLK_TA_REMAP, 0,
1090                         sizeof(r), &r, blk_trace_request_get_cgid(q, rq));
1091         rcu_read_unlock();
1092 }
1093
1094 /**
1095  * blk_add_driver_data - Add binary message with driver-specific data
1096  * @q:          queue the io is for
1097  * @rq:         io request
1098  * @data:       driver-specific data
1099  * @len:        length of driver-specific data
1100  *
1101  * Description:
1102  *     Some drivers might want to write driver-specific data per request.
1103  *
1104  **/
1105 void blk_add_driver_data(struct request_queue *q,
1106                          struct request *rq,
1107                          void *data, size_t len)
1108 {
1109         struct blk_trace *bt;
1110
1111         rcu_read_lock();
1112         bt = rcu_dereference(q->blk_trace);
1113         if (likely(!bt)) {
1114                 rcu_read_unlock();
1115                 return;
1116         }
1117
1118         __blk_add_trace(bt, blk_rq_trace_sector(rq), blk_rq_bytes(rq), 0, 0,
1119                                 BLK_TA_DRV_DATA, 0, len, data,
1120                                 blk_trace_request_get_cgid(q, rq));
1121         rcu_read_unlock();
1122 }
1123 EXPORT_SYMBOL_GPL(blk_add_driver_data);
1124
1125 static void blk_register_tracepoints(void)
1126 {
1127         int ret;
1128
1129         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1130         WARN_ON(ret);
1131         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1132         WARN_ON(ret);
1133         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1134         WARN_ON(ret);
1135         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1136         WARN_ON(ret);
1137         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1138         WARN_ON(ret);
1139         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1140         WARN_ON(ret);
1141         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1142         WARN_ON(ret);
1143         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1144         WARN_ON(ret);
1145         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1146         WARN_ON(ret);
1147         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1148         WARN_ON(ret);
1149         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1150         WARN_ON(ret);
1151         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1152         WARN_ON(ret);
1153         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1154         WARN_ON(ret);
1155         ret = register_trace_block_split(blk_add_trace_split, NULL);
1156         WARN_ON(ret);
1157         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1158         WARN_ON(ret);
1159         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1160         WARN_ON(ret);
1161 }
1162
1163 static void blk_unregister_tracepoints(void)
1164 {
1165         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1166         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1167         unregister_trace_block_split(blk_add_trace_split, NULL);
1168         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1169         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1170         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1171         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1172         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1173         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1174         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1175         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1176         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1177         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1178         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1179         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1180         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1181
1182         tracepoint_synchronize_unregister();
1183 }
1184
1185 /*
1186  * struct blk_io_tracer formatting routines
1187  */
1188
1189 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1190 {
1191         int i = 0;
1192         int tc = t->action >> BLK_TC_SHIFT;
1193
1194         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1195                 rwbs[i++] = 'N';
1196                 goto out;
1197         }
1198
1199         if (tc & BLK_TC_FLUSH)
1200                 rwbs[i++] = 'F';
1201
1202         if (tc & BLK_TC_DISCARD)
1203                 rwbs[i++] = 'D';
1204         else if (tc & BLK_TC_WRITE)
1205                 rwbs[i++] = 'W';
1206         else if (t->bytes)
1207                 rwbs[i++] = 'R';
1208         else
1209                 rwbs[i++] = 'N';
1210
1211         if (tc & BLK_TC_FUA)
1212                 rwbs[i++] = 'F';
1213         if (tc & BLK_TC_AHEAD)
1214                 rwbs[i++] = 'A';
1215         if (tc & BLK_TC_SYNC)
1216                 rwbs[i++] = 'S';
1217         if (tc & BLK_TC_META)
1218                 rwbs[i++] = 'M';
1219 out:
1220         rwbs[i] = '\0';
1221 }
1222
1223 static inline
1224 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1225 {
1226         return (const struct blk_io_trace *)ent;
1227 }
1228
1229 static inline const void *pdu_start(const struct trace_entry *ent, bool has_cg)
1230 {
1231         return (void *)(te_blk_io_trace(ent) + 1) + (has_cg ? sizeof(u64) : 0);
1232 }
1233
1234 static inline u64 t_cgid(const struct trace_entry *ent)
1235 {
1236         return *(u64 *)(te_blk_io_trace(ent) + 1);
1237 }
1238
1239 static inline int pdu_real_len(const struct trace_entry *ent, bool has_cg)
1240 {
1241         return te_blk_io_trace(ent)->pdu_len - (has_cg ? sizeof(u64) : 0);
1242 }
1243
1244 static inline u32 t_action(const struct trace_entry *ent)
1245 {
1246         return te_blk_io_trace(ent)->action;
1247 }
1248
1249 static inline u32 t_bytes(const struct trace_entry *ent)
1250 {
1251         return te_blk_io_trace(ent)->bytes;
1252 }
1253
1254 static inline u32 t_sec(const struct trace_entry *ent)
1255 {
1256         return te_blk_io_trace(ent)->bytes >> 9;
1257 }
1258
1259 static inline unsigned long long t_sector(const struct trace_entry *ent)
1260 {
1261         return te_blk_io_trace(ent)->sector;
1262 }
1263
1264 static inline __u16 t_error(const struct trace_entry *ent)
1265 {
1266         return te_blk_io_trace(ent)->error;
1267 }
1268
1269 static __u64 get_pdu_int(const struct trace_entry *ent, bool has_cg)
1270 {
1271         const __be64 *val = pdu_start(ent, has_cg);
1272         return be64_to_cpu(*val);
1273 }
1274
1275 typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act,
1276         bool has_cg);
1277
1278 static void blk_log_action_classic(struct trace_iterator *iter, const char *act,
1279         bool has_cg)
1280 {
1281         char rwbs[RWBS_LEN];
1282         unsigned long long ts  = iter->ts;
1283         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1284         unsigned secs          = (unsigned long)ts;
1285         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1286
1287         fill_rwbs(rwbs, t);
1288
1289         trace_seq_printf(&iter->seq,
1290                          "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1291                          MAJOR(t->device), MINOR(t->device), iter->cpu,
1292                          secs, nsec_rem, iter->ent->pid, act, rwbs);
1293 }
1294
1295 static void blk_log_action(struct trace_iterator *iter, const char *act,
1296         bool has_cg)
1297 {
1298         char rwbs[RWBS_LEN];
1299         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1300
1301         fill_rwbs(rwbs, t);
1302         if (has_cg) {
1303                 u64 id = t_cgid(iter->ent);
1304
1305                 if (blk_tracer_flags.val & TRACE_BLK_OPT_CGNAME) {
1306                         char blkcg_name_buf[NAME_MAX + 1] = "<...>";
1307
1308                         cgroup_path_from_kernfs_id(id, blkcg_name_buf,
1309                                 sizeof(blkcg_name_buf));
1310                         trace_seq_printf(&iter->seq, "%3d,%-3d %s %2s %3s ",
1311                                  MAJOR(t->device), MINOR(t->device),
1312                                  blkcg_name_buf, act, rwbs);
1313                 } else {
1314                         /*
1315                          * The cgid portion used to be "INO,GEN".  Userland
1316                          * builds a FILEID_INO32_GEN fid out of them and
1317                          * opens the cgroup using open_by_handle_at(2).
1318                          * While 32bit ino setups are still the same, 64bit
1319                          * ones now use the 64bit ino as the whole ID and
1320                          * no longer use generation.
1321                          *
1322                          * Regarldess of the content, always output
1323                          * "LOW32,HIGH32" so that FILEID_INO32_GEN fid can
1324                          * be mapped back to @id on both 64 and 32bit ino
1325                          * setups.  See __kernfs_fh_to_dentry().
1326                          */
1327                         trace_seq_printf(&iter->seq,
1328                                  "%3d,%-3d %llx,%-llx %2s %3s ",
1329                                  MAJOR(t->device), MINOR(t->device),
1330                                  id & U32_MAX, id >> 32, act, rwbs);
1331                 }
1332         } else
1333                 trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1334                                  MAJOR(t->device), MINOR(t->device), act, rwbs);
1335 }
1336
1337 static void blk_log_dump_pdu(struct trace_seq *s,
1338         const struct trace_entry *ent, bool has_cg)
1339 {
1340         const unsigned char *pdu_buf;
1341         int pdu_len;
1342         int i, end;
1343
1344         pdu_buf = pdu_start(ent, has_cg);
1345         pdu_len = pdu_real_len(ent, has_cg);
1346
1347         if (!pdu_len)
1348                 return;
1349
1350         /* find the last zero that needs to be printed */
1351         for (end = pdu_len - 1; end >= 0; end--)
1352                 if (pdu_buf[end])
1353                         break;
1354         end++;
1355
1356         trace_seq_putc(s, '(');
1357
1358         for (i = 0; i < pdu_len; i++) {
1359
1360                 trace_seq_printf(s, "%s%02x",
1361                                  i == 0 ? "" : " ", pdu_buf[i]);
1362
1363                 /*
1364                  * stop when the rest is just zeroes and indicate so
1365                  * with a ".." appended
1366                  */
1367                 if (i == end && end != pdu_len - 1) {
1368                         trace_seq_puts(s, " ..) ");
1369                         return;
1370                 }
1371         }
1372
1373         trace_seq_puts(s, ") ");
1374 }
1375
1376 static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1377 {
1378         char cmd[TASK_COMM_LEN];
1379
1380         trace_find_cmdline(ent->pid, cmd);
1381
1382         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1383                 trace_seq_printf(s, "%u ", t_bytes(ent));
1384                 blk_log_dump_pdu(s, ent, has_cg);
1385                 trace_seq_printf(s, "[%s]\n", cmd);
1386         } else {
1387                 if (t_sec(ent))
1388                         trace_seq_printf(s, "%llu + %u [%s]\n",
1389                                                 t_sector(ent), t_sec(ent), cmd);
1390                 else
1391                         trace_seq_printf(s, "[%s]\n", cmd);
1392         }
1393 }
1394
1395 static void blk_log_with_error(struct trace_seq *s,
1396                               const struct trace_entry *ent, bool has_cg)
1397 {
1398         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1399                 blk_log_dump_pdu(s, ent, has_cg);
1400                 trace_seq_printf(s, "[%d]\n", t_error(ent));
1401         } else {
1402                 if (t_sec(ent))
1403                         trace_seq_printf(s, "%llu + %u [%d]\n",
1404                                          t_sector(ent),
1405                                          t_sec(ent), t_error(ent));
1406                 else
1407                         trace_seq_printf(s, "%llu [%d]\n",
1408                                          t_sector(ent), t_error(ent));
1409         }
1410 }
1411
1412 static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1413 {
1414         const struct blk_io_trace_remap *__r = pdu_start(ent, has_cg);
1415
1416         trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1417                          t_sector(ent), t_sec(ent),
1418                          MAJOR(be32_to_cpu(__r->device_from)),
1419                          MINOR(be32_to_cpu(__r->device_from)),
1420                          be64_to_cpu(__r->sector_from));
1421 }
1422
1423 static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1424 {
1425         char cmd[TASK_COMM_LEN];
1426
1427         trace_find_cmdline(ent->pid, cmd);
1428
1429         trace_seq_printf(s, "[%s]\n", cmd);
1430 }
1431
1432 static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1433 {
1434         char cmd[TASK_COMM_LEN];
1435
1436         trace_find_cmdline(ent->pid, cmd);
1437
1438         trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent, has_cg));
1439 }
1440
1441 static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1442 {
1443         char cmd[TASK_COMM_LEN];
1444
1445         trace_find_cmdline(ent->pid, cmd);
1446
1447         trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1448                          get_pdu_int(ent, has_cg), cmd);
1449 }
1450
1451 static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent,
1452                         bool has_cg)
1453 {
1454
1455         trace_seq_putmem(s, pdu_start(ent, has_cg),
1456                 pdu_real_len(ent, has_cg));
1457         trace_seq_putc(s, '\n');
1458 }
1459
1460 /*
1461  * struct tracer operations
1462  */
1463
1464 static void blk_tracer_print_header(struct seq_file *m)
1465 {
1466         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1467                 return;
1468         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1469                     "#  |     |     |           |   |   |\n");
1470 }
1471
1472 static void blk_tracer_start(struct trace_array *tr)
1473 {
1474         blk_tracer_enabled = true;
1475 }
1476
1477 static int blk_tracer_init(struct trace_array *tr)
1478 {
1479         blk_tr = tr;
1480         blk_tracer_start(tr);
1481         return 0;
1482 }
1483
1484 static void blk_tracer_stop(struct trace_array *tr)
1485 {
1486         blk_tracer_enabled = false;
1487 }
1488
1489 static void blk_tracer_reset(struct trace_array *tr)
1490 {
1491         blk_tracer_stop(tr);
1492 }
1493
1494 static const struct {
1495         const char *act[2];
1496         void       (*print)(struct trace_seq *s, const struct trace_entry *ent,
1497                             bool has_cg);
1498 } what2act[] = {
1499         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1500         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1501         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1502         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1503         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1504         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1505         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1506         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1507         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1508         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1509         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1510         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1511         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1512         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1513         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1514 };
1515
1516 static enum print_line_t print_one_line(struct trace_iterator *iter,
1517                                         bool classic)
1518 {
1519         struct trace_array *tr = iter->tr;
1520         struct trace_seq *s = &iter->seq;
1521         const struct blk_io_trace *t;
1522         u16 what;
1523         bool long_act;
1524         blk_log_action_t *log_action;
1525         bool has_cg;
1526
1527         t          = te_blk_io_trace(iter->ent);
1528         what       = (t->action & ((1 << BLK_TC_SHIFT) - 1)) & ~__BLK_TA_CGROUP;
1529         long_act   = !!(tr->trace_flags & TRACE_ITER_VERBOSE);
1530         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1531         has_cg     = t->action & __BLK_TA_CGROUP;
1532
1533         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1534                 log_action(iter, long_act ? "message" : "m", has_cg);
1535                 blk_log_msg(s, iter->ent, has_cg);
1536                 return trace_handle_return(s);
1537         }
1538
1539         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1540                 trace_seq_printf(s, "Unknown action %x\n", what);
1541         else {
1542                 log_action(iter, what2act[what].act[long_act], has_cg);
1543                 what2act[what].print(s, iter->ent, has_cg);
1544         }
1545
1546         return trace_handle_return(s);
1547 }
1548
1549 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1550                                                int flags, struct trace_event *event)
1551 {
1552         return print_one_line(iter, false);
1553 }
1554
1555 static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1556 {
1557         struct trace_seq *s = &iter->seq;
1558         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1559         const int offset = offsetof(struct blk_io_trace, sector);
1560         struct blk_io_trace old = {
1561                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1562                 .time     = iter->ts,
1563         };
1564
1565         trace_seq_putmem(s, &old, offset);
1566         trace_seq_putmem(s, &t->sector,
1567                          sizeof(old) - offset + t->pdu_len);
1568 }
1569
1570 static enum print_line_t
1571 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1572                              struct trace_event *event)
1573 {
1574         blk_trace_synthesize_old_trace(iter);
1575
1576         return trace_handle_return(&iter->seq);
1577 }
1578
1579 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1580 {
1581         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1582                 return TRACE_TYPE_UNHANDLED;
1583
1584         return print_one_line(iter, true);
1585 }
1586
1587 static int
1588 blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1589 {
1590         /* don't output context-info for blk_classic output */
1591         if (bit == TRACE_BLK_OPT_CLASSIC) {
1592                 if (set)
1593                         tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1594                 else
1595                         tr->trace_flags |= TRACE_ITER_CONTEXT_INFO;
1596         }
1597         return 0;
1598 }
1599
1600 static struct tracer blk_tracer __read_mostly = {
1601         .name           = "blk",
1602         .init           = blk_tracer_init,
1603         .reset          = blk_tracer_reset,
1604         .start          = blk_tracer_start,
1605         .stop           = blk_tracer_stop,
1606         .print_header   = blk_tracer_print_header,
1607         .print_line     = blk_tracer_print_line,
1608         .flags          = &blk_tracer_flags,
1609         .set_flag       = blk_tracer_set_flag,
1610 };
1611
1612 static struct trace_event_functions trace_blk_event_funcs = {
1613         .trace          = blk_trace_event_print,
1614         .binary         = blk_trace_event_print_binary,
1615 };
1616
1617 static struct trace_event trace_blk_event = {
1618         .type           = TRACE_BLK,
1619         .funcs          = &trace_blk_event_funcs,
1620 };
1621
1622 static int __init init_blk_tracer(void)
1623 {
1624         if (!register_trace_event(&trace_blk_event)) {
1625                 pr_warn("Warning: could not register block events\n");
1626                 return 1;
1627         }
1628
1629         if (register_tracer(&blk_tracer) != 0) {
1630                 pr_warn("Warning: could not register the block tracer\n");
1631                 unregister_trace_event(&trace_blk_event);
1632                 return 1;
1633         }
1634
1635         return 0;
1636 }
1637
1638 device_initcall(init_blk_tracer);
1639
1640 static int blk_trace_remove_queue(struct request_queue *q)
1641 {
1642         struct blk_trace *bt;
1643
1644         bt = rcu_replace_pointer(q->blk_trace, NULL,
1645                                  lockdep_is_held(&q->blk_trace_mutex));
1646         if (bt == NULL)
1647                 return -EINVAL;
1648
1649         put_probe_ref();
1650         synchronize_rcu();
1651         blk_trace_free(bt);
1652         return 0;
1653 }
1654
1655 /*
1656  * Setup everything required to start tracing
1657  */
1658 static int blk_trace_setup_queue(struct request_queue *q,
1659                                  struct block_device *bdev)
1660 {
1661         struct blk_trace *bt = NULL;
1662         int ret = -ENOMEM;
1663
1664         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1665         if (!bt)
1666                 return -ENOMEM;
1667
1668         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1669         if (!bt->msg_data)
1670                 goto free_bt;
1671
1672         bt->dev = bdev->bd_dev;
1673         bt->act_mask = (u16)-1;
1674
1675         blk_trace_setup_lba(bt, bdev);
1676
1677         rcu_assign_pointer(q->blk_trace, bt);
1678         get_probe_ref();
1679         return 0;
1680
1681 free_bt:
1682         blk_trace_free(bt);
1683         return ret;
1684 }
1685
1686 /*
1687  * sysfs interface to enable and configure tracing
1688  */
1689
1690 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1691                                          struct device_attribute *attr,
1692                                          char *buf);
1693 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1694                                           struct device_attribute *attr,
1695                                           const char *buf, size_t count);
1696 #define BLK_TRACE_DEVICE_ATTR(_name) \
1697         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1698                     sysfs_blk_trace_attr_show, \
1699                     sysfs_blk_trace_attr_store)
1700
1701 static BLK_TRACE_DEVICE_ATTR(enable);
1702 static BLK_TRACE_DEVICE_ATTR(act_mask);
1703 static BLK_TRACE_DEVICE_ATTR(pid);
1704 static BLK_TRACE_DEVICE_ATTR(start_lba);
1705 static BLK_TRACE_DEVICE_ATTR(end_lba);
1706
1707 static struct attribute *blk_trace_attrs[] = {
1708         &dev_attr_enable.attr,
1709         &dev_attr_act_mask.attr,
1710         &dev_attr_pid.attr,
1711         &dev_attr_start_lba.attr,
1712         &dev_attr_end_lba.attr,
1713         NULL
1714 };
1715
1716 struct attribute_group blk_trace_attr_group = {
1717         .name  = "trace",
1718         .attrs = blk_trace_attrs,
1719 };
1720
1721 static const struct {
1722         int mask;
1723         const char *str;
1724 } mask_maps[] = {
1725         { BLK_TC_READ,          "read"          },
1726         { BLK_TC_WRITE,         "write"         },
1727         { BLK_TC_FLUSH,         "flush"         },
1728         { BLK_TC_SYNC,          "sync"          },
1729         { BLK_TC_QUEUE,         "queue"         },
1730         { BLK_TC_REQUEUE,       "requeue"       },
1731         { BLK_TC_ISSUE,         "issue"         },
1732         { BLK_TC_COMPLETE,      "complete"      },
1733         { BLK_TC_FS,            "fs"            },
1734         { BLK_TC_PC,            "pc"            },
1735         { BLK_TC_NOTIFY,        "notify"        },
1736         { BLK_TC_AHEAD,         "ahead"         },
1737         { BLK_TC_META,          "meta"          },
1738         { BLK_TC_DISCARD,       "discard"       },
1739         { BLK_TC_DRV_DATA,      "drv_data"      },
1740         { BLK_TC_FUA,           "fua"           },
1741 };
1742
1743 static int blk_trace_str2mask(const char *str)
1744 {
1745         int i;
1746         int mask = 0;
1747         char *buf, *s, *token;
1748
1749         buf = kstrdup(str, GFP_KERNEL);
1750         if (buf == NULL)
1751                 return -ENOMEM;
1752         s = strstrip(buf);
1753
1754         while (1) {
1755                 token = strsep(&s, ",");
1756                 if (token == NULL)
1757                         break;
1758
1759                 if (*token == '\0')
1760                         continue;
1761
1762                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1763                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1764                                 mask |= mask_maps[i].mask;
1765                                 break;
1766                         }
1767                 }
1768                 if (i == ARRAY_SIZE(mask_maps)) {
1769                         mask = -EINVAL;
1770                         break;
1771                 }
1772         }
1773         kfree(buf);
1774
1775         return mask;
1776 }
1777
1778 static ssize_t blk_trace_mask2str(char *buf, int mask)
1779 {
1780         int i;
1781         char *p = buf;
1782
1783         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1784                 if (mask & mask_maps[i].mask) {
1785                         p += sprintf(p, "%s%s",
1786                                     (p == buf) ? "" : ",", mask_maps[i].str);
1787                 }
1788         }
1789         *p++ = '\n';
1790
1791         return p - buf;
1792 }
1793
1794 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1795 {
1796         if (bdev->bd_disk == NULL)
1797                 return NULL;
1798
1799         return bdev_get_queue(bdev);
1800 }
1801
1802 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1803                                          struct device_attribute *attr,
1804                                          char *buf)
1805 {
1806         struct hd_struct *p = dev_to_part(dev);
1807         struct request_queue *q;
1808         struct block_device *bdev;
1809         struct blk_trace *bt;
1810         ssize_t ret = -ENXIO;
1811
1812         bdev = bdget(part_devt(p));
1813         if (bdev == NULL)
1814                 goto out;
1815
1816         q = blk_trace_get_queue(bdev);
1817         if (q == NULL)
1818                 goto out_bdput;
1819
1820         mutex_lock(&q->blk_trace_mutex);
1821
1822         bt = rcu_dereference_protected(q->blk_trace,
1823                                        lockdep_is_held(&q->blk_trace_mutex));
1824         if (attr == &dev_attr_enable) {
1825                 ret = sprintf(buf, "%u\n", !!bt);
1826                 goto out_unlock_bdev;
1827         }
1828
1829         if (bt == NULL)
1830                 ret = sprintf(buf, "disabled\n");
1831         else if (attr == &dev_attr_act_mask)
1832                 ret = blk_trace_mask2str(buf, bt->act_mask);
1833         else if (attr == &dev_attr_pid)
1834                 ret = sprintf(buf, "%u\n", bt->pid);
1835         else if (attr == &dev_attr_start_lba)
1836                 ret = sprintf(buf, "%llu\n", bt->start_lba);
1837         else if (attr == &dev_attr_end_lba)
1838                 ret = sprintf(buf, "%llu\n", bt->end_lba);
1839
1840 out_unlock_bdev:
1841         mutex_unlock(&q->blk_trace_mutex);
1842 out_bdput:
1843         bdput(bdev);
1844 out:
1845         return ret;
1846 }
1847
1848 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1849                                           struct device_attribute *attr,
1850                                           const char *buf, size_t count)
1851 {
1852         struct block_device *bdev;
1853         struct request_queue *q;
1854         struct hd_struct *p;
1855         struct blk_trace *bt;
1856         u64 value;
1857         ssize_t ret = -EINVAL;
1858
1859         if (count == 0)
1860                 goto out;
1861
1862         if (attr == &dev_attr_act_mask) {
1863                 if (kstrtoull(buf, 0, &value)) {
1864                         /* Assume it is a list of trace category names */
1865                         ret = blk_trace_str2mask(buf);
1866                         if (ret < 0)
1867                                 goto out;
1868                         value = ret;
1869                 }
1870         } else if (kstrtoull(buf, 0, &value))
1871                 goto out;
1872
1873         ret = -ENXIO;
1874
1875         p = dev_to_part(dev);
1876         bdev = bdget(part_devt(p));
1877         if (bdev == NULL)
1878                 goto out;
1879
1880         q = blk_trace_get_queue(bdev);
1881         if (q == NULL)
1882                 goto out_bdput;
1883
1884         mutex_lock(&q->blk_trace_mutex);
1885
1886         bt = rcu_dereference_protected(q->blk_trace,
1887                                        lockdep_is_held(&q->blk_trace_mutex));
1888         if (attr == &dev_attr_enable) {
1889                 if (!!value == !!bt) {
1890                         ret = 0;
1891                         goto out_unlock_bdev;
1892                 }
1893                 if (value)
1894                         ret = blk_trace_setup_queue(q, bdev);
1895                 else
1896                         ret = blk_trace_remove_queue(q);
1897                 goto out_unlock_bdev;
1898         }
1899
1900         ret = 0;
1901         if (bt == NULL) {
1902                 ret = blk_trace_setup_queue(q, bdev);
1903                 bt = rcu_dereference_protected(q->blk_trace,
1904                                 lockdep_is_held(&q->blk_trace_mutex));
1905         }
1906
1907         if (ret == 0) {
1908                 if (attr == &dev_attr_act_mask)
1909                         bt->act_mask = value;
1910                 else if (attr == &dev_attr_pid)
1911                         bt->pid = value;
1912                 else if (attr == &dev_attr_start_lba)
1913                         bt->start_lba = value;
1914                 else if (attr == &dev_attr_end_lba)
1915                         bt->end_lba = value;
1916         }
1917
1918 out_unlock_bdev:
1919         mutex_unlock(&q->blk_trace_mutex);
1920 out_bdput:
1921         bdput(bdev);
1922 out:
1923         return ret ? ret : count;
1924 }
1925
1926 int blk_trace_init_sysfs(struct device *dev)
1927 {
1928         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1929 }
1930
1931 void blk_trace_remove_sysfs(struct device *dev)
1932 {
1933         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1934 }
1935
1936 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1937
1938 #ifdef CONFIG_EVENT_TRACING
1939
1940 void blk_fill_rwbs(char *rwbs, unsigned int op, int bytes)
1941 {
1942         int i = 0;
1943
1944         if (op & REQ_PREFLUSH)
1945                 rwbs[i++] = 'F';
1946
1947         switch (op & REQ_OP_MASK) {
1948         case REQ_OP_WRITE:
1949         case REQ_OP_WRITE_SAME:
1950                 rwbs[i++] = 'W';
1951                 break;
1952         case REQ_OP_DISCARD:
1953                 rwbs[i++] = 'D';
1954                 break;
1955         case REQ_OP_SECURE_ERASE:
1956                 rwbs[i++] = 'D';
1957                 rwbs[i++] = 'E';
1958                 break;
1959         case REQ_OP_FLUSH:
1960                 rwbs[i++] = 'F';
1961                 break;
1962         case REQ_OP_READ:
1963                 rwbs[i++] = 'R';
1964                 break;
1965         default:
1966                 rwbs[i++] = 'N';
1967         }
1968
1969         if (op & REQ_FUA)
1970                 rwbs[i++] = 'F';
1971         if (op & REQ_RAHEAD)
1972                 rwbs[i++] = 'A';
1973         if (op & REQ_SYNC)
1974                 rwbs[i++] = 'S';
1975         if (op & REQ_META)
1976                 rwbs[i++] = 'M';
1977
1978         rwbs[i] = '\0';
1979 }
1980 EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1981
1982 #endif /* CONFIG_EVENT_TRACING */
1983