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->debugfs_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->debugfs_mutex);
 366         ret = __blk_trace_remove(q);
 367         mutex_unlock(&q->debugfs_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 const 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         lockdep_assert_held(&q->debugfs_mutex);
 487
 488         if (!buts->buf_size || !buts->buf_nr)
 489                 return -EINVAL;
 490
 491         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 492         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 493
 494         /*
 495          * some device names have larger paths - convert the slashes
 496          * to underscores for this to work as expected
 497          */
 498         strreplace(buts->name, '/', '_');
 499
 500         /*
 501          * bdev can be NULL, as with scsi-generic, this is a helpful as
 502          * we can be.
 503          */
 504         if (rcu_dereference_protected(q->blk_trace,
 505                                       lockdep_is_held(&q->debugfs_mutex))) {
 506                 pr_warn("Concurrent blktraces are not allowed on %s\n",
 507                         buts->name);
 508                 return -EBUSY;
 509         }
 510
 511         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 512         if (!bt)
 513                 return -ENOMEM;
 514
 515         ret = -ENOMEM;
 516         bt->sequence = alloc_percpu(unsigned long);
 517         if (!bt->sequence)
 518                 goto err;
 519
 520         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 521         if (!bt->msg_data)
 522                 goto err;
 523
 524         /*
 525          * When tracing the whole disk reuse the existing debugfs directory
 526          * created by the block layer on init. For partitions block devices,
 527          * and scsi-generic block devices we create a temporary new debugfs
 528          * directory that will be removed once the trace ends.
 529          */
 530         if (bdev && !bdev_is_partition(bdev))
 531                 dir = q->debugfs_dir;
 532         else
 533                 bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);
 534
 535         /*
 536          * As blktrace relies on debugfs for its interface the debugfs directory
 537          * is required, contrary to the usual mantra of not checking for debugfs
 538          * files or directories.
 539          */
 540         if (IS_ERR_OR_NULL(dir)) {
 541                 pr_warn("debugfs_dir not present for %s so skipping\n",
 542                         buts->name);
 543                 ret = -ENOENT;
 544                 goto err;
 545         }
 546
 547         bt->dev = dev;
 548         atomic_set(&bt->dropped, 0);
 549         INIT_LIST_HEAD(&bt->running_list);
 550
 551         ret = -EIO;
 552         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 553                                                &blk_dropped_fops);
 554
 555         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 556
 557         bt->rchan = relay_open("trace", dir, buts->buf_size,
 558                                 buts->buf_nr, &blk_relay_callbacks, bt);
 559         if (!bt->rchan)
 560                 goto err;
 561
 562         bt->act_mask = buts->act_mask;
 563         if (!bt->act_mask)
 564                 bt->act_mask = (u16) -1;
 565
 566         blk_trace_setup_lba(bt, bdev);
 567
 568         /* overwrite with user settings */
 569         if (buts->start_lba)
 570                 bt->start_lba = buts->start_lba;
 571         if (buts->end_lba)
 572                 bt->end_lba = buts->end_lba;
 573
 574         bt->pid = buts->pid;
 575         bt->trace_state = Blktrace_setup;
 576
 577         rcu_assign_pointer(q->blk_trace, bt);
 578         get_probe_ref();
 579
 580         ret = 0;
 581 err:
 582         if (ret)
 583                 blk_trace_free(bt);
 584         return ret;
 585 }
 586
 587 static int __blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 588                              struct block_device *bdev, char __user *arg)
 589 {
 590         struct blk_user_trace_setup buts;
 591         int ret;
 592
 593         ret = copy_from_user(&buts, arg, sizeof(buts));
 594         if (ret)
 595                 return -EFAULT;
 596
 597         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 598         if (ret)
 599                 return ret;
 600
 601         if (copy_to_user(arg, &buts, sizeof(buts))) {
 602                 __blk_trace_remove(q);
 603                 return -EFAULT;
 604         }
 605         return 0;
 606 }
 607
 608 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 609                     struct block_device *bdev,
 610                     char __user *arg)
 611 {
 612         int ret;
 613
 614         mutex_lock(&q->debugfs_mutex);
 615         ret = __blk_trace_setup(q, name, dev, bdev, arg);
 616         mutex_unlock(&q->debugfs_mutex);
 617
 618         return ret;
 619 }
 620 EXPORT_SYMBOL_GPL(blk_trace_setup);
 621
 622 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 623 static int compat_blk_trace_setup(struct request_queue *q, char *name,
 624                                   dev_t dev, struct block_device *bdev,
 625                                   char __user *arg)
 626 {
 627         struct blk_user_trace_setup buts;
 628         struct compat_blk_user_trace_setup cbuts;
 629         int ret;
 630
 631         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
 632                 return -EFAULT;
 633
 634         buts = (struct blk_user_trace_setup) {
 635                 .act_mask = cbuts.act_mask,
 636                 .buf_size = cbuts.buf_size,
 637                 .buf_nr = cbuts.buf_nr,
 638                 .start_lba = cbuts.start_lba,
 639                 .end_lba = cbuts.end_lba,
 640                 .pid = cbuts.pid,
 641         };
 642
 643         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 644         if (ret)
 645                 return ret;
 646
 647         if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
 648                 __blk_trace_remove(q);
 649                 return -EFAULT;
 650         }
 651
 652         return 0;
 653 }
 654 #endif
 655
 656 static int __blk_trace_startstop(struct request_queue *q, int start)
 657 {
 658         int ret;
 659         struct blk_trace *bt;
 660
 661         bt = rcu_dereference_protected(q->blk_trace,
 662                                        lockdep_is_held(&q->debugfs_mutex));
 663         if (bt == NULL)
 664                 return -EINVAL;
 665
 666         /*
 667          * For starting a trace, we can transition from a setup or stopped
 668          * trace. For stopping a trace, the state must be running
 669          */
 670         ret = -EINVAL;
 671         if (start) {
 672                 if (bt->trace_state == Blktrace_setup ||
 673                     bt->trace_state == Blktrace_stopped) {
 674                         blktrace_seq++;
 675                         smp_mb();
 676                         bt->trace_state = Blktrace_running;
 677                         spin_lock_irq(&running_trace_lock);
 678                         list_add(&bt->running_list, &running_trace_list);
 679                         spin_unlock_irq(&running_trace_lock);
 680
 681                         trace_note_time(bt);
 682                         ret = 0;
 683                 }
 684         } else {
 685                 if (bt->trace_state == Blktrace_running) {
 686                         bt->trace_state = Blktrace_stopped;
 687                         spin_lock_irq(&running_trace_lock);
 688                         list_del_init(&bt->running_list);
 689                         spin_unlock_irq(&running_trace_lock);
 690                         relay_flush(bt->rchan);
 691                         ret = 0;
 692                 }
 693         }
 694
 695         return ret;
 696 }
 697
 698 int blk_trace_startstop(struct request_queue *q, int start)
 699 {
 700         int ret;
 701
 702         mutex_lock(&q->debugfs_mutex);
 703         ret = __blk_trace_startstop(q, start);
 704         mutex_unlock(&q->debugfs_mutex);
 705
 706         return ret;
 707 }
 708 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 709
 710 /*
 711  * When reading or writing the blktrace sysfs files, the references to the
 712  * opened sysfs or device files should prevent the underlying block device
 713  * from being removed. So no further delete protection is really needed.
 714  */
 715
 716 /**
 717  * blk_trace_ioctl: - handle the ioctls associated with tracing
 718  * @bdev:       the block device
 719  * @cmd:        the ioctl cmd
 720  * @arg:        the argument data, if any
 721  *
 722  **/
 723 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 724 {
 725         struct request_queue *q;
 726         int ret, start = 0;
 727         char b[BDEVNAME_SIZE];
 728
 729         q = bdev_get_queue(bdev);
 730         if (!q)
 731                 return -ENXIO;
 732
 733         mutex_lock(&q->debugfs_mutex);
 734
 735         switch (cmd) {
 736         case BLKTRACESETUP:
 737                 bdevname(bdev, b);
 738                 ret = __blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 739                 break;
 740 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 741         case BLKTRACESETUP32:
 742                 bdevname(bdev, b);
 743                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 744                 break;
 745 #endif
 746         case BLKTRACESTART:
 747                 start = 1;
 748                 fallthrough;
 749         case BLKTRACESTOP:
 750                 ret = __blk_trace_startstop(q, start);
 751                 break;
 752         case BLKTRACETEARDOWN:
 753                 ret = __blk_trace_remove(q);
 754                 break;
 755         default:
 756                 ret = -ENOTTY;
 757                 break;
 758         }
 759
 760         mutex_unlock(&q->debugfs_mutex);
 761         return ret;
 762 }
 763
 764 /**
 765  * blk_trace_shutdown: - stop and cleanup trace structures
 766  * @q:    the request queue associated with the device
 767  *
 768  **/
 769 void blk_trace_shutdown(struct request_queue *q)
 770 {
 771         mutex_lock(&q->debugfs_mutex);
 772         if (rcu_dereference_protected(q->blk_trace,
 773                                       lockdep_is_held(&q->debugfs_mutex))) {
 774                 __blk_trace_startstop(q, 0);
 775                 __blk_trace_remove(q);
 776         }
 777
 778         mutex_unlock(&q->debugfs_mutex);
 779 }
 780
 781 #ifdef CONFIG_BLK_CGROUP
 782 static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 783 {
 784         struct blk_trace *bt;
 785
 786         /* We don't use the 'bt' value here except as an optimization... */
 787         bt = rcu_dereference_protected(q->blk_trace, 1);
 788         if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
 789                 return 0;
 790
 791         if (!bio->bi_blkg)
 792                 return 0;
 793         return cgroup_id(bio_blkcg(bio)->css.cgroup);
 794 }
 795 #else
 796 static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 797 {
 798         return 0;
 799 }
 800 #endif
 801
 802 static u64
 803 blk_trace_request_get_cgid(struct request_queue *q, struct request *rq)
 804 {
 805         if (!rq->bio)
 806                 return 0;
 807         /* Use the first bio */
 808         return blk_trace_bio_get_cgid(q, rq->bio);
 809 }
 810
 811 /*
 812  * blktrace probes
 813  */
 814
 815 /**
 816  * blk_add_trace_rq - Add a trace for a request oriented action
 817  * @rq:         the source request
 818  * @error:      return status to log
 819  * @nr_bytes:   number of completed bytes
 820  * @what:       the action
 821  * @cgid:       the cgroup info
 822  *
 823  * Description:
 824  *     Records an action against a request. Will log the bio offset + size.
 825  *
 826  **/
 827 static void blk_add_trace_rq(struct request *rq, int error,
 828                              unsigned int nr_bytes, u32 what, u64 cgid)
 829 {
 830         struct blk_trace *bt;
 831
 832         rcu_read_lock();
 833         bt = rcu_dereference(rq->q->blk_trace);
 834         if (likely(!bt)) {
 835                 rcu_read_unlock();
 836                 return;
 837         }
 838
 839         if (blk_rq_is_passthrough(rq))
 840                 what |= BLK_TC_ACT(BLK_TC_PC);
 841         else
 842                 what |= BLK_TC_ACT(BLK_TC_FS);
 843
 844         __blk_add_trace(bt, blk_rq_trace_sector(rq), nr_bytes, req_op(rq),
 845                         rq->cmd_flags, what, error, 0, NULL, cgid);
 846         rcu_read_unlock();
 847 }
 848
 849 static void blk_add_trace_rq_insert(void *ignore,
 850                                     struct request_queue *q, struct request *rq)
 851 {
 852         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_INSERT,
 853                          blk_trace_request_get_cgid(q, rq));
 854 }
 855
 856 static void blk_add_trace_rq_issue(void *ignore,
 857                                    struct request_queue *q, struct request *rq)
 858 {
 859         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_ISSUE,
 860                          blk_trace_request_get_cgid(q, rq));
 861 }
 862
 863 static void blk_add_trace_rq_merge(void *ignore,
 864                                    struct request_queue *q, struct request *rq)
 865 {
 866         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_BACKMERGE,
 867                          blk_trace_request_get_cgid(q, rq));
 868 }
 869
 870 static void blk_add_trace_rq_requeue(void *ignore,
 871                                      struct request_queue *q,
 872                                      struct request *rq)
 873 {
 874         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_REQUEUE,
 875                          blk_trace_request_get_cgid(q, rq));
 876 }
 877
 878 static void blk_add_trace_rq_complete(void *ignore, struct request *rq,
 879                         int error, unsigned int nr_bytes)
 880 {
 881         blk_add_trace_rq(rq, error, nr_bytes, BLK_TA_COMPLETE,
 882                          blk_trace_request_get_cgid(rq->q, rq));
 883 }
 884
 885 /**
 886  * blk_add_trace_bio - Add a trace for a bio oriented action
 887  * @q:          queue the io is for
 888  * @bio:        the source bio
 889  * @what:       the action
 890  * @error:      error, if any
 891  *
 892  * Description:
 893  *     Records an action against a bio. Will log the bio offset + size.
 894  *
 895  **/
 896 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 897                               u32 what, int error)
 898 {
 899         struct blk_trace *bt;
 900
 901         rcu_read_lock();
 902         bt = rcu_dereference(q->blk_trace);
 903         if (likely(!bt)) {
 904                 rcu_read_unlock();
 905                 return;
 906         }
 907
 908         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
 909                         bio_op(bio), bio->bi_opf, what, error, 0, NULL,
 910                         blk_trace_bio_get_cgid(q, bio));
 911         rcu_read_unlock();
 912 }
 913
 914 static void blk_add_trace_bio_bounce(void *ignore,
 915                                      struct request_queue *q, struct bio *bio)
 916 {
 917         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
 918 }
 919
 920 static void blk_add_trace_bio_complete(void *ignore,
 921                                        struct request_queue *q, struct bio *bio)
 922 {
 923         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE,
 924                           blk_status_to_errno(bio->bi_status));
 925 }
 926
 927 static void blk_add_trace_bio_backmerge(void *ignore,
 928                                         struct request_queue *q,
 929                                         struct request *rq,
 930                                         struct bio *bio)
 931 {
 932         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
 933 }
 934
 935 static void blk_add_trace_bio_frontmerge(void *ignore,
 936                                          struct request_queue *q,
 937                                          struct request *rq,
 938                                          struct bio *bio)
 939 {
 940         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
 941 }
 942
 943 static void blk_add_trace_bio_queue(void *ignore,
 944                                     struct request_queue *q, struct bio *bio)
 945 {
 946         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
 947 }
 948
 949 static void blk_add_trace_getrq(void *ignore,
 950                                 struct request_queue *q,
 951                                 struct bio *bio, int rw)
 952 {
 953         if (bio)
 954                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
 955         else {
 956                 struct blk_trace *bt;
 957
 958                 rcu_read_lock();
 959                 bt = rcu_dereference(q->blk_trace);
 960                 if (bt)
 961                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_GETRQ, 0, 0,
 962                                         NULL, 0);
 963                 rcu_read_unlock();
 964         }
 965 }
 966
 967
 968 static void blk_add_trace_sleeprq(void *ignore,
 969                                   struct request_queue *q,
 970                                   struct bio *bio, int rw)
 971 {
 972         if (bio)
 973                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
 974         else {
 975                 struct blk_trace *bt;
 976
 977                 rcu_read_lock();
 978                 bt = rcu_dereference(q->blk_trace);
 979                 if (bt)
 980                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_SLEEPRQ,
 981                                         0, 0, NULL, 0);
 982                 rcu_read_unlock();
 983         }
 984 }
 985
 986 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 987 {
 988         struct blk_trace *bt;
 989
 990         rcu_read_lock();
 991         bt = rcu_dereference(q->blk_trace);
 992         if (bt)
 993                 __blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL, 0);
 994         rcu_read_unlock();
 995 }
 996
 997 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 998                                     unsigned int depth, bool explicit)
 999 {
1000         struct blk_trace *bt;
1001
1002         rcu_read_lock();
1003         bt = rcu_dereference(q->blk_trace);
1004         if (bt) {
1005                 __be64 rpdu = cpu_to_be64(depth);
1006                 u32 what;
1007
1008                 if (explicit)
1009                         what = BLK_TA_UNPLUG_IO;
1010                 else
1011                         what = BLK_TA_UNPLUG_TIMER;
1012
1013                 __blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu, 0);
1014         }
1015         rcu_read_unlock();
1016 }
1017
1018 static void blk_add_trace_split(void *ignore,
1019                                 struct request_queue *q, struct bio *bio,
1020                                 unsigned int pdu)
1021 {
1022         struct blk_trace *bt;
1023
1024         rcu_read_lock();
1025         bt = rcu_dereference(q->blk_trace);
1026         if (bt) {
1027                 __be64 rpdu = cpu_to_be64(pdu);
1028
1029                 __blk_add_trace(bt, bio->bi_iter.bi_sector,
1030                                 bio->bi_iter.bi_size, bio_op(bio), bio->bi_opf,
1031                                 BLK_TA_SPLIT,
1032                                 blk_status_to_errno(bio->bi_status),
1033                                 sizeof(rpdu), &rpdu,
1034                                 blk_trace_bio_get_cgid(q, bio));
1035         }
1036         rcu_read_unlock();
1037 }
1038
1039 /**
1040  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
1041  * @ignore:     trace callback data parameter (not used)
1042  * @q:          queue the io is for
1043  * @bio:        the source bio
1044  * @dev:        target device
1045  * @from:       source sector
1046  *
1047  * Description:
1048  *     Device mapper or raid target sometimes need to split a bio because
1049  *     it spans a stripe (or similar). Add a trace for that action.
1050  *
1051  **/
1052 static void blk_add_trace_bio_remap(void *ignore,
1053                                     struct request_queue *q, struct bio *bio,
1054                                     dev_t dev, sector_t from)
1055 {
1056         struct blk_trace *bt;
1057         struct blk_io_trace_remap r;
1058
1059         rcu_read_lock();
1060         bt = rcu_dereference(q->blk_trace);
1061         if (likely(!bt)) {
1062                 rcu_read_unlock();
1063                 return;
1064         }
1065
1066         r.device_from = cpu_to_be32(dev);
1067         r.device_to   = cpu_to_be32(bio_dev(bio));
1068         r.sector_from = cpu_to_be64(from);
1069
1070         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
1071                         bio_op(bio), bio->bi_opf, BLK_TA_REMAP,
1072                         blk_status_to_errno(bio->bi_status),
1073                         sizeof(r), &r, blk_trace_bio_get_cgid(q, bio));
1074         rcu_read_unlock();
1075 }
1076
1077 /**
1078  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
1079  * @ignore:     trace callback data parameter (not used)
1080  * @q:          queue the io is for
1081  * @rq:         the source request
1082  * @dev:        target device
1083  * @from:       source sector
1084  *
1085  * Description:
1086  *     Device mapper remaps request to other devices.
1087  *     Add a trace for that action.
1088  *
1089  **/
1090 static void blk_add_trace_rq_remap(void *ignore,
1091                                    struct request_queue *q,
1092                                    struct request *rq, dev_t dev,
1093                                    sector_t from)
1094 {
1095         struct blk_trace *bt;
1096         struct blk_io_trace_remap r;
1097
1098         rcu_read_lock();
1099         bt = rcu_dereference(q->blk_trace);
1100         if (likely(!bt)) {
1101                 rcu_read_unlock();
1102                 return;
1103         }
1104
1105         r.device_from = cpu_to_be32(dev);
1106         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
1107         r.sector_from = cpu_to_be64(from);
1108
1109         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
1110                         rq_data_dir(rq), 0, BLK_TA_REMAP, 0,
1111                         sizeof(r), &r, blk_trace_request_get_cgid(q, rq));
1112         rcu_read_unlock();
1113 }
1114
1115 /**
1116  * blk_add_driver_data - Add binary message with driver-specific data
1117  * @q:          queue the io is for
1118  * @rq:         io request
1119  * @data:       driver-specific data
1120  * @len:        length of driver-specific data
1121  *
1122  * Description:
1123  *     Some drivers might want to write driver-specific data per request.
1124  *
1125  **/
1126 void blk_add_driver_data(struct request_queue *q,
1127                          struct request *rq,
1128                          void *data, size_t len)
1129 {
1130         struct blk_trace *bt;
1131
1132         rcu_read_lock();
1133         bt = rcu_dereference(q->blk_trace);
1134         if (likely(!bt)) {
1135                 rcu_read_unlock();
1136                 return;
1137         }
1138
1139         __blk_add_trace(bt, blk_rq_trace_sector(rq), blk_rq_bytes(rq), 0, 0,
1140                                 BLK_TA_DRV_DATA, 0, len, data,
1141                                 blk_trace_request_get_cgid(q, rq));
1142         rcu_read_unlock();
1143 }
1144 EXPORT_SYMBOL_GPL(blk_add_driver_data);
1145
1146 static void blk_register_tracepoints(void)
1147 {
1148         int ret;
1149
1150         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1151         WARN_ON(ret);
1152         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1153         WARN_ON(ret);
1154         ret = register_trace_block_rq_merge(blk_add_trace_rq_merge, NULL);
1155         WARN_ON(ret);
1156         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1157         WARN_ON(ret);
1158         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1159         WARN_ON(ret);
1160         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1161         WARN_ON(ret);
1162         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1163         WARN_ON(ret);
1164         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1165         WARN_ON(ret);
1166         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1167         WARN_ON(ret);
1168         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1169         WARN_ON(ret);
1170         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1171         WARN_ON(ret);
1172         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1173         WARN_ON(ret);
1174         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1175         WARN_ON(ret);
1176         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1177         WARN_ON(ret);
1178         ret = register_trace_block_split(blk_add_trace_split, NULL);
1179         WARN_ON(ret);
1180         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1181         WARN_ON(ret);
1182         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1183         WARN_ON(ret);
1184 }
1185
1186 static void blk_unregister_tracepoints(void)
1187 {
1188         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1189         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1190         unregister_trace_block_split(blk_add_trace_split, NULL);
1191         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1192         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1193         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1194         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1195         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1196         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1197         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1198         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1199         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1200         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1201         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1202         unregister_trace_block_rq_merge(blk_add_trace_rq_merge, NULL);
1203         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1204         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1205
1206         tracepoint_synchronize_unregister();
1207 }
1208
1209 /*
1210  * struct blk_io_tracer formatting routines
1211  */
1212
1213 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1214 {
1215         int i = 0;
1216         int tc = t->action >> BLK_TC_SHIFT;
1217
1218         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1219                 rwbs[i++] = 'N';
1220                 goto out;
1221         }
1222
1223         if (tc & BLK_TC_FLUSH)
1224                 rwbs[i++] = 'F';
1225
1226         if (tc & BLK_TC_DISCARD)
1227                 rwbs[i++] = 'D';
1228         else if (tc & BLK_TC_WRITE)
1229                 rwbs[i++] = 'W';
1230         else if (t->bytes)
1231                 rwbs[i++] = 'R';
1232         else
1233                 rwbs[i++] = 'N';
1234
1235         if (tc & BLK_TC_FUA)
1236                 rwbs[i++] = 'F';
1237         if (tc & BLK_TC_AHEAD)
1238                 rwbs[i++] = 'A';
1239         if (tc & BLK_TC_SYNC)
1240                 rwbs[i++] = 'S';
1241         if (tc & BLK_TC_META)
1242                 rwbs[i++] = 'M';
1243 out:
1244         rwbs[i] = '\0';
1245 }
1246
1247 static inline
1248 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1249 {
1250         return (const struct blk_io_trace *)ent;
1251 }
1252
1253 static inline const void *pdu_start(const struct trace_entry *ent, bool has_cg)
1254 {
1255         return (void *)(te_blk_io_trace(ent) + 1) + (has_cg ? sizeof(u64) : 0);
1256 }
1257
1258 static inline u64 t_cgid(const struct trace_entry *ent)
1259 {
1260         return *(u64 *)(te_blk_io_trace(ent) + 1);
1261 }
1262
1263 static inline int pdu_real_len(const struct trace_entry *ent, bool has_cg)
1264 {
1265         return te_blk_io_trace(ent)->pdu_len - (has_cg ? sizeof(u64) : 0);
1266 }
1267
1268 static inline u32 t_action(const struct trace_entry *ent)
1269 {
1270         return te_blk_io_trace(ent)->action;
1271 }
1272
1273 static inline u32 t_bytes(const struct trace_entry *ent)
1274 {
1275         return te_blk_io_trace(ent)->bytes;
1276 }
1277
1278 static inline u32 t_sec(const struct trace_entry *ent)
1279 {
1280         return te_blk_io_trace(ent)->bytes >> 9;
1281 }
1282
1283 static inline unsigned long long t_sector(const struct trace_entry *ent)
1284 {
1285         return te_blk_io_trace(ent)->sector;
1286 }
1287
1288 static inline __u16 t_error(const struct trace_entry *ent)
1289 {
1290         return te_blk_io_trace(ent)->error;
1291 }
1292
1293 static __u64 get_pdu_int(const struct trace_entry *ent, bool has_cg)
1294 {
1295         const __be64 *val = pdu_start(ent, has_cg);
1296         return be64_to_cpu(*val);
1297 }
1298
1299 typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act,
1300         bool has_cg);
1301
1302 static void blk_log_action_classic(struct trace_iterator *iter, const char *act,
1303         bool has_cg)
1304 {
1305         char rwbs[RWBS_LEN];
1306         unsigned long long ts  = iter->ts;
1307         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1308         unsigned secs          = (unsigned long)ts;
1309         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1310
1311         fill_rwbs(rwbs, t);
1312
1313         trace_seq_printf(&iter->seq,
1314                          "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1315                          MAJOR(t->device), MINOR(t->device), iter->cpu,
1316                          secs, nsec_rem, iter->ent->pid, act, rwbs);
1317 }
1318
1319 static void blk_log_action(struct trace_iterator *iter, const char *act,
1320         bool has_cg)
1321 {
1322         char rwbs[RWBS_LEN];
1323         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1324
1325         fill_rwbs(rwbs, t);
1326         if (has_cg) {
1327                 u64 id = t_cgid(iter->ent);
1328
1329                 if (blk_tracer_flags.val & TRACE_BLK_OPT_CGNAME) {
1330                         char blkcg_name_buf[NAME_MAX + 1] = "<...>";
1331
1332                         cgroup_path_from_kernfs_id(id, blkcg_name_buf,
1333                                 sizeof(blkcg_name_buf));
1334                         trace_seq_printf(&iter->seq, "%3d,%-3d %s %2s %3s ",
1335                                  MAJOR(t->device), MINOR(t->device),
1336                                  blkcg_name_buf, act, rwbs);
1337                 } else {
1338                         /*
1339                          * The cgid portion used to be "INO,GEN".  Userland
1340                          * builds a FILEID_INO32_GEN fid out of them and
1341                          * opens the cgroup using open_by_handle_at(2).
1342                          * While 32bit ino setups are still the same, 64bit
1343                          * ones now use the 64bit ino as the whole ID and
1344                          * no longer use generation.
1345                          *
1346                          * Regarldess of the content, always output
1347                          * "LOW32,HIGH32" so that FILEID_INO32_GEN fid can
1348                          * be mapped back to @id on both 64 and 32bit ino
1349                          * setups.  See __kernfs_fh_to_dentry().
1350                          */
1351                         trace_seq_printf(&iter->seq,
1352                                  "%3d,%-3d %llx,%-llx %2s %3s ",
1353                                  MAJOR(t->device), MINOR(t->device),
1354                                  id & U32_MAX, id >> 32, act, rwbs);
1355                 }
1356         } else
1357                 trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1358                                  MAJOR(t->device), MINOR(t->device), act, rwbs);
1359 }
1360
1361 static void blk_log_dump_pdu(struct trace_seq *s,
1362         const struct trace_entry *ent, bool has_cg)
1363 {
1364         const unsigned char *pdu_buf;
1365         int pdu_len;
1366         int i, end;
1367
1368         pdu_buf = pdu_start(ent, has_cg);
1369         pdu_len = pdu_real_len(ent, has_cg);
1370
1371         if (!pdu_len)
1372                 return;
1373
1374         /* find the last zero that needs to be printed */
1375         for (end = pdu_len - 1; end >= 0; end--)
1376                 if (pdu_buf[end])
1377                         break;
1378         end++;
1379
1380         trace_seq_putc(s, '(');
1381
1382         for (i = 0; i < pdu_len; i++) {
1383
1384                 trace_seq_printf(s, "%s%02x",
1385                                  i == 0 ? "" : " ", pdu_buf[i]);
1386
1387                 /*
1388                  * stop when the rest is just zeroes and indicate so
1389                  * with a ".." appended
1390                  */
1391                 if (i == end && end != pdu_len - 1) {
1392                         trace_seq_puts(s, " ..) ");
1393                         return;
1394                 }
1395         }
1396
1397         trace_seq_puts(s, ") ");
1398 }
1399
1400 static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1401 {
1402         char cmd[TASK_COMM_LEN];
1403
1404         trace_find_cmdline(ent->pid, cmd);
1405
1406         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1407                 trace_seq_printf(s, "%u ", t_bytes(ent));
1408                 blk_log_dump_pdu(s, ent, has_cg);
1409                 trace_seq_printf(s, "[%s]\n", cmd);
1410         } else {
1411                 if (t_sec(ent))
1412                         trace_seq_printf(s, "%llu + %u [%s]\n",
1413                                                 t_sector(ent), t_sec(ent), cmd);
1414                 else
1415                         trace_seq_printf(s, "[%s]\n", cmd);
1416         }
1417 }
1418
1419 static void blk_log_with_error(struct trace_seq *s,
1420                               const struct trace_entry *ent, bool has_cg)
1421 {
1422         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1423                 blk_log_dump_pdu(s, ent, has_cg);
1424                 trace_seq_printf(s, "[%d]\n", t_error(ent));
1425         } else {
1426                 if (t_sec(ent))
1427                         trace_seq_printf(s, "%llu + %u [%d]\n",
1428                                          t_sector(ent),
1429                                          t_sec(ent), t_error(ent));
1430                 else
1431                         trace_seq_printf(s, "%llu [%d]\n",
1432                                          t_sector(ent), t_error(ent));
1433         }
1434 }
1435
1436 static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1437 {
1438         const struct blk_io_trace_remap *__r = pdu_start(ent, has_cg);
1439
1440         trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1441                          t_sector(ent), t_sec(ent),
1442                          MAJOR(be32_to_cpu(__r->device_from)),
1443                          MINOR(be32_to_cpu(__r->device_from)),
1444                          be64_to_cpu(__r->sector_from));
1445 }
1446
1447 static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1448 {
1449         char cmd[TASK_COMM_LEN];
1450
1451         trace_find_cmdline(ent->pid, cmd);
1452
1453         trace_seq_printf(s, "[%s]\n", cmd);
1454 }
1455
1456 static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1457 {
1458         char cmd[TASK_COMM_LEN];
1459
1460         trace_find_cmdline(ent->pid, cmd);
1461
1462         trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent, has_cg));
1463 }
1464
1465 static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1466 {
1467         char cmd[TASK_COMM_LEN];
1468
1469         trace_find_cmdline(ent->pid, cmd);
1470
1471         trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1472                          get_pdu_int(ent, has_cg), cmd);
1473 }
1474
1475 static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent,
1476                         bool has_cg)
1477 {
1478
1479         trace_seq_putmem(s, pdu_start(ent, has_cg),
1480                 pdu_real_len(ent, has_cg));
1481         trace_seq_putc(s, '\n');
1482 }
1483
1484 /*
1485  * struct tracer operations
1486  */
1487
1488 static void blk_tracer_print_header(struct seq_file *m)
1489 {
1490         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1491                 return;
1492         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1493                     "#  |     |     |           |   |   |\n");
1494 }
1495
1496 static void blk_tracer_start(struct trace_array *tr)
1497 {
1498         blk_tracer_enabled = true;
1499 }
1500
1501 static int blk_tracer_init(struct trace_array *tr)
1502 {
1503         blk_tr = tr;
1504         blk_tracer_start(tr);
1505         return 0;
1506 }
1507
1508 static void blk_tracer_stop(struct trace_array *tr)
1509 {
1510         blk_tracer_enabled = false;
1511 }
1512
1513 static void blk_tracer_reset(struct trace_array *tr)
1514 {
1515         blk_tracer_stop(tr);
1516 }
1517
1518 static const struct {
1519         const char *act[2];
1520         void       (*print)(struct trace_seq *s, const struct trace_entry *ent,
1521                             bool has_cg);
1522 } what2act[] = {
1523         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1524         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1525         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1526         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1527         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1528         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1529         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1530         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1531         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1532         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1533         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1534         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1535         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1536         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1537         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1538 };
1539
1540 static enum print_line_t print_one_line(struct trace_iterator *iter,
1541                                         bool classic)
1542 {
1543         struct trace_array *tr = iter->tr;
1544         struct trace_seq *s = &iter->seq;
1545         const struct blk_io_trace *t;
1546         u16 what;
1547         bool long_act;
1548         blk_log_action_t *log_action;
1549         bool has_cg;
1550
1551         t          = te_blk_io_trace(iter->ent);
1552         what       = (t->action & ((1 << BLK_TC_SHIFT) - 1)) & ~__BLK_TA_CGROUP;
1553         long_act   = !!(tr->trace_flags & TRACE_ITER_VERBOSE);
1554         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1555         has_cg     = t->action & __BLK_TA_CGROUP;
1556
1557         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1558                 log_action(iter, long_act ? "message" : "m", has_cg);
1559                 blk_log_msg(s, iter->ent, has_cg);
1560                 return trace_handle_return(s);
1561         }
1562
1563         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1564                 trace_seq_printf(s, "Unknown action %x\n", what);
1565         else {
1566                 log_action(iter, what2act[what].act[long_act], has_cg);
1567                 what2act[what].print(s, iter->ent, has_cg);
1568         }
1569
1570         return trace_handle_return(s);
1571 }
1572
1573 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1574                                                int flags, struct trace_event *event)
1575 {
1576         return print_one_line(iter, false);
1577 }
1578
1579 static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1580 {
1581         struct trace_seq *s = &iter->seq;
1582         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1583         const int offset = offsetof(struct blk_io_trace, sector);
1584         struct blk_io_trace old = {
1585                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1586                 .time     = iter->ts,
1587         };
1588
1589         trace_seq_putmem(s, &old, offset);
1590         trace_seq_putmem(s, &t->sector,
1591                          sizeof(old) - offset + t->pdu_len);
1592 }
1593
1594 static enum print_line_t
1595 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1596                              struct trace_event *event)
1597 {
1598         blk_trace_synthesize_old_trace(iter);
1599
1600         return trace_handle_return(&iter->seq);
1601 }
1602
1603 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1604 {
1605         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1606                 return TRACE_TYPE_UNHANDLED;
1607
1608         return print_one_line(iter, true);
1609 }
1610
1611 static int
1612 blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1613 {
1614         /* don't output context-info for blk_classic output */
1615         if (bit == TRACE_BLK_OPT_CLASSIC) {
1616                 if (set)
1617                         tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1618                 else
1619                         tr->trace_flags |= TRACE_ITER_CONTEXT_INFO;
1620         }
1621         return 0;
1622 }
1623
1624 static struct tracer blk_tracer __read_mostly = {
1625         .name           = "blk",
1626         .init           = blk_tracer_init,
1627         .reset          = blk_tracer_reset,
1628         .start          = blk_tracer_start,
1629         .stop           = blk_tracer_stop,
1630         .print_header   = blk_tracer_print_header,
1631         .print_line     = blk_tracer_print_line,
1632         .flags          = &blk_tracer_flags,
1633         .set_flag       = blk_tracer_set_flag,
1634 };
1635
1636 static struct trace_event_functions trace_blk_event_funcs = {
1637         .trace          = blk_trace_event_print,
1638         .binary         = blk_trace_event_print_binary,
1639 };
1640
1641 static struct trace_event trace_blk_event = {
1642         .type           = TRACE_BLK,
1643         .funcs          = &trace_blk_event_funcs,
1644 };
1645
1646 static int __init init_blk_tracer(void)
1647 {
1648         if (!register_trace_event(&trace_blk_event)) {
1649                 pr_warn("Warning: could not register block events\n");
1650                 return 1;
1651         }
1652
1653         if (register_tracer(&blk_tracer) != 0) {
1654                 pr_warn("Warning: could not register the block tracer\n");
1655                 unregister_trace_event(&trace_blk_event);
1656                 return 1;
1657         }
1658
1659         return 0;
1660 }
1661
1662 device_initcall(init_blk_tracer);
1663
1664 static int blk_trace_remove_queue(struct request_queue *q)
1665 {
1666         struct blk_trace *bt;
1667
1668         bt = rcu_replace_pointer(q->blk_trace, NULL,
1669                                  lockdep_is_held(&q->debugfs_mutex));
1670         if (bt == NULL)
1671                 return -EINVAL;
1672
1673         put_probe_ref();
1674         synchronize_rcu();
1675         blk_trace_free(bt);
1676         return 0;
1677 }
1678
1679 /*
1680  * Setup everything required to start tracing
1681  */
1682 static int blk_trace_setup_queue(struct request_queue *q,
1683                                  struct block_device *bdev)
1684 {
1685         struct blk_trace *bt = NULL;
1686         int ret = -ENOMEM;
1687
1688         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1689         if (!bt)
1690                 return -ENOMEM;
1691
1692         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1693         if (!bt->msg_data)
1694                 goto free_bt;
1695
1696         bt->dev = bdev->bd_dev;
1697         bt->act_mask = (u16)-1;
1698
1699         blk_trace_setup_lba(bt, bdev);
1700
1701         rcu_assign_pointer(q->blk_trace, bt);
1702         get_probe_ref();
1703         return 0;
1704
1705 free_bt:
1706         blk_trace_free(bt);
1707         return ret;
1708 }
1709
1710 /*
1711  * sysfs interface to enable and configure tracing
1712  */
1713
1714 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1715                                          struct device_attribute *attr,
1716                                          char *buf);
1717 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1718                                           struct device_attribute *attr,
1719                                           const char *buf, size_t count);
1720 #define BLK_TRACE_DEVICE_ATTR(_name) \
1721         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1722                     sysfs_blk_trace_attr_show, \
1723                     sysfs_blk_trace_attr_store)
1724
1725 static BLK_TRACE_DEVICE_ATTR(enable);
1726 static BLK_TRACE_DEVICE_ATTR(act_mask);
1727 static BLK_TRACE_DEVICE_ATTR(pid);
1728 static BLK_TRACE_DEVICE_ATTR(start_lba);
1729 static BLK_TRACE_DEVICE_ATTR(end_lba);
1730
1731 static struct attribute *blk_trace_attrs[] = {
1732         &dev_attr_enable.attr,
1733         &dev_attr_act_mask.attr,
1734         &dev_attr_pid.attr,
1735         &dev_attr_start_lba.attr,
1736         &dev_attr_end_lba.attr,
1737         NULL
1738 };
1739
1740 struct attribute_group blk_trace_attr_group = {
1741         .name  = "trace",
1742         .attrs = blk_trace_attrs,
1743 };
1744
1745 static const struct {
1746         int mask;
1747         const char *str;
1748 } mask_maps[] = {
1749         { BLK_TC_READ,          "read"          },
1750         { BLK_TC_WRITE,         "write"         },
1751         { BLK_TC_FLUSH,         "flush"         },
1752         { BLK_TC_SYNC,          "sync"          },
1753         { BLK_TC_QUEUE,         "queue"         },
1754         { BLK_TC_REQUEUE,       "requeue"       },
1755         { BLK_TC_ISSUE,         "issue"         },
1756         { BLK_TC_COMPLETE,      "complete"      },
1757         { BLK_TC_FS,            "fs"            },
1758         { BLK_TC_PC,            "pc"            },
1759         { BLK_TC_NOTIFY,        "notify"        },
1760         { BLK_TC_AHEAD,         "ahead"         },
1761         { BLK_TC_META,          "meta"          },
1762         { BLK_TC_DISCARD,       "discard"       },
1763         { BLK_TC_DRV_DATA,      "drv_data"      },
1764         { BLK_TC_FUA,           "fua"           },
1765 };
1766
1767 static int blk_trace_str2mask(const char *str)
1768 {
1769         int i;
1770         int mask = 0;
1771         char *buf, *s, *token;
1772
1773         buf = kstrdup(str, GFP_KERNEL);
1774         if (buf == NULL)
1775                 return -ENOMEM;
1776         s = strstrip(buf);
1777
1778         while (1) {
1779                 token = strsep(&s, ",");
1780                 if (token == NULL)
1781                         break;
1782
1783                 if (*token == '\0')
1784                         continue;
1785
1786                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1787                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1788                                 mask |= mask_maps[i].mask;
1789                                 break;
1790                         }
1791                 }
1792                 if (i == ARRAY_SIZE(mask_maps)) {
1793                         mask = -EINVAL;
1794                         break;
1795                 }
1796         }
1797         kfree(buf);
1798
1799         return mask;
1800 }
1801
1802 static ssize_t blk_trace_mask2str(char *buf, int mask)
1803 {
1804         int i;
1805         char *p = buf;
1806
1807         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1808                 if (mask & mask_maps[i].mask) {
1809                         p += sprintf(p, "%s%s",
1810                                     (p == buf) ? "" : ",", mask_maps[i].str);
1811                 }
1812         }
1813         *p++ = '\n';
1814
1815         return p - buf;
1816 }
1817
1818 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1819 {
1820         if (bdev->bd_disk == NULL)
1821                 return NULL;
1822
1823         return bdev_get_queue(bdev);
1824 }
1825
1826 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1827                                          struct device_attribute *attr,
1828                                          char *buf)
1829 {
1830         struct block_device *bdev = bdget_part(dev_to_part(dev));
1831         struct request_queue *q;
1832         struct blk_trace *bt;
1833         ssize_t ret = -ENXIO;
1834
1835         if (bdev == NULL)
1836                 goto out;
1837
1838         q = blk_trace_get_queue(bdev);
1839         if (q == NULL)
1840                 goto out_bdput;
1841
1842         mutex_lock(&q->debugfs_mutex);
1843
1844         bt = rcu_dereference_protected(q->blk_trace,
1845                                        lockdep_is_held(&q->debugfs_mutex));
1846         if (attr == &dev_attr_enable) {
1847                 ret = sprintf(buf, "%u\n", !!bt);
1848                 goto out_unlock_bdev;
1849         }
1850
1851         if (bt == NULL)
1852                 ret = sprintf(buf, "disabled\n");
1853         else if (attr == &dev_attr_act_mask)
1854                 ret = blk_trace_mask2str(buf, bt->act_mask);
1855         else if (attr == &dev_attr_pid)
1856                 ret = sprintf(buf, "%u\n", bt->pid);
1857         else if (attr == &dev_attr_start_lba)
1858                 ret = sprintf(buf, "%llu\n", bt->start_lba);
1859         else if (attr == &dev_attr_end_lba)
1860                 ret = sprintf(buf, "%llu\n", bt->end_lba);
1861
1862 out_unlock_bdev:
1863         mutex_unlock(&q->debugfs_mutex);
1864 out_bdput:
1865         bdput(bdev);
1866 out:
1867         return ret;
1868 }
1869
1870 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1871                                           struct device_attribute *attr,
1872                                           const char *buf, size_t count)
1873 {
1874         struct block_device *bdev;
1875         struct request_queue *q;
1876         struct blk_trace *bt;
1877         u64 value;
1878         ssize_t ret = -EINVAL;
1879
1880         if (count == 0)
1881                 goto out;
1882
1883         if (attr == &dev_attr_act_mask) {
1884                 if (kstrtoull(buf, 0, &value)) {
1885                         /* Assume it is a list of trace category names */
1886                         ret = blk_trace_str2mask(buf);
1887                         if (ret < 0)
1888                                 goto out;
1889                         value = ret;
1890                 }
1891         } else if (kstrtoull(buf, 0, &value))
1892                 goto out;
1893
1894         ret = -ENXIO;
1895         bdev = bdget_part(dev_to_part(dev));
1896         if (bdev == NULL)
1897                 goto out;
1898
1899         q = blk_trace_get_queue(bdev);
1900         if (q == NULL)
1901                 goto out_bdput;
1902
1903         mutex_lock(&q->debugfs_mutex);
1904
1905         bt = rcu_dereference_protected(q->blk_trace,
1906                                        lockdep_is_held(&q->debugfs_mutex));
1907         if (attr == &dev_attr_enable) {
1908                 if (!!value == !!bt) {
1909                         ret = 0;
1910                         goto out_unlock_bdev;
1911                 }
1912                 if (value)
1913                         ret = blk_trace_setup_queue(q, bdev);
1914                 else
1915                         ret = blk_trace_remove_queue(q);
1916                 goto out_unlock_bdev;
1917         }
1918
1919         ret = 0;
1920         if (bt == NULL) {
1921                 ret = blk_trace_setup_queue(q, bdev);
1922                 bt = rcu_dereference_protected(q->blk_trace,
1923                                 lockdep_is_held(&q->debugfs_mutex));
1924         }
1925
1926         if (ret == 0) {
1927                 if (attr == &dev_attr_act_mask)
1928                         bt->act_mask = value;
1929                 else if (attr == &dev_attr_pid)
1930                         bt->pid = value;
1931                 else if (attr == &dev_attr_start_lba)
1932                         bt->start_lba = value;
1933                 else if (attr == &dev_attr_end_lba)
1934                         bt->end_lba = value;
1935         }
1936
1937 out_unlock_bdev:
1938         mutex_unlock(&q->debugfs_mutex);
1939 out_bdput:
1940         bdput(bdev);
1941 out:
1942         return ret ? ret : count;
1943 }
1944
1945 int blk_trace_init_sysfs(struct device *dev)
1946 {
1947         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1948 }
1949
1950 void blk_trace_remove_sysfs(struct device *dev)
1951 {
1952         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1953 }
1954
1955 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1956
1957 #ifdef CONFIG_EVENT_TRACING
1958
1959 void blk_fill_rwbs(char *rwbs, unsigned int op, int bytes)
1960 {
1961         int i = 0;
1962
1963         if (op & REQ_PREFLUSH)
1964                 rwbs[i++] = 'F';
1965
1966         switch (op & REQ_OP_MASK) {
1967         case REQ_OP_WRITE:
1968         case REQ_OP_WRITE_SAME:
1969                 rwbs[i++] = 'W';
1970                 break;
1971         case REQ_OP_DISCARD:
1972                 rwbs[i++] = 'D';
1973                 break;
1974         case REQ_OP_SECURE_ERASE:
1975                 rwbs[i++] = 'D';
1976                 rwbs[i++] = 'E';
1977                 break;
1978         case REQ_OP_FLUSH:
1979                 rwbs[i++] = 'F';
1980                 break;
1981         case REQ_OP_READ:
1982                 rwbs[i++] = 'R';
1983                 break;
1984         default:
1985                 rwbs[i++] = 'N';
1986         }
1987
1988         if (op & REQ_FUA)
1989                 rwbs[i++] = 'F';
1990         if (op & REQ_RAHEAD)
1991                 rwbs[i++] = 'A';
1992         if (op & REQ_SYNC)
1993                 rwbs[i++] = 'S';
1994         if (op & REQ_META)
1995                 rwbs[i++] = 'M';
1996
1997         rwbs[i] = '\0';
1998 }
1999 EXPORT_SYMBOL_GPL(blk_fill_rwbs);
2000
2001 #endif /* CONFIG_EVENT_TRACING */
2002