kernel/trace/blktrace.c

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