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                 /* fall through */
 727         case BLKTRACESTOP:
 728                 ret = __blk_trace_startstop(q, start);
 729                 break;
 730         case BLKTRACETEARDOWN:
 731                 ret = __blk_trace_remove(q);
 732                 break;
 733         default:
 734                 ret = -ENOTTY;
 735                 break;
 736         }
 737
 738         mutex_unlock(&q->blk_trace_mutex);
 739         return ret;
 740 }
 741
 742 /**
 743  * blk_trace_shutdown: - stop and cleanup trace structures
 744  * @q:    the request queue associated with the device
 745  *
 746  **/
 747 void blk_trace_shutdown(struct request_queue *q)
 748 {
 749         mutex_lock(&q->blk_trace_mutex);
 750
 751         if (q->blk_trace) {
 752                 __blk_trace_startstop(q, 0);
 753                 __blk_trace_remove(q);
 754         }
 755
 756         mutex_unlock(&q->blk_trace_mutex);
 757 }
 758
 759 #ifdef CONFIG_BLK_CGROUP
 760 static union kernfs_node_id *
 761 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 762 {
 763         struct blk_trace *bt = q->blk_trace;
 764
 765         if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
 766                 return NULL;
 767
 768         if (!bio->bi_blkg)
 769                 return NULL;
 770         return cgroup_get_kernfs_id(bio_blkcg(bio)->css.cgroup);
 771 }
 772 #else
 773 static union kernfs_node_id *
 774 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 775 {
 776         return NULL;
 777 }
 778 #endif
 779
 780 static union kernfs_node_id *
 781 blk_trace_request_get_cgid(struct request_queue *q, struct request *rq)
 782 {
 783         if (!rq->bio)
 784                 return NULL;
 785         /* Use the first bio */
 786         return blk_trace_bio_get_cgid(q, rq->bio);
 787 }
 788
 789 /*
 790  * blktrace probes
 791  */
 792
 793 /**
 794  * blk_add_trace_rq - Add a trace for a request oriented action
 795  * @rq:         the source request
 796  * @error:      return status to log
 797  * @nr_bytes:   number of completed bytes
 798  * @what:       the action
 799  * @cgid:       the cgroup info
 800  *
 801  * Description:
 802  *     Records an action against a request. Will log the bio offset + size.
 803  *
 804  **/
 805 static void blk_add_trace_rq(struct request *rq, int error,
 806                              unsigned int nr_bytes, u32 what,
 807                              union kernfs_node_id *cgid)
 808 {
 809         struct blk_trace *bt = rq->q->blk_trace;
 810
 811         if (likely(!bt))
 812                 return;
 813
 814         if (blk_rq_is_passthrough(rq))
 815                 what |= BLK_TC_ACT(BLK_TC_PC);
 816         else
 817                 what |= BLK_TC_ACT(BLK_TC_FS);
 818
 819         __blk_add_trace(bt, blk_rq_trace_sector(rq), nr_bytes, req_op(rq),
 820                         rq->cmd_flags, what, error, 0, NULL, cgid);
 821 }
 822
 823 static void blk_add_trace_rq_insert(void *ignore,
 824                                     struct request_queue *q, struct request *rq)
 825 {
 826         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_INSERT,
 827                          blk_trace_request_get_cgid(q, rq));
 828 }
 829
 830 static void blk_add_trace_rq_issue(void *ignore,
 831                                    struct request_queue *q, struct request *rq)
 832 {
 833         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_ISSUE,
 834                          blk_trace_request_get_cgid(q, rq));
 835 }
 836
 837 static void blk_add_trace_rq_requeue(void *ignore,
 838                                      struct request_queue *q,
 839                                      struct request *rq)
 840 {
 841         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_REQUEUE,
 842                          blk_trace_request_get_cgid(q, rq));
 843 }
 844
 845 static void blk_add_trace_rq_complete(void *ignore, struct request *rq,
 846                         int error, unsigned int nr_bytes)
 847 {
 848         blk_add_trace_rq(rq, error, nr_bytes, BLK_TA_COMPLETE,
 849                          blk_trace_request_get_cgid(rq->q, rq));
 850 }
 851
 852 /**
 853  * blk_add_trace_bio - Add a trace for a bio oriented action
 854  * @q:          queue the io is for
 855  * @bio:        the source bio
 856  * @what:       the action
 857  * @error:      error, if any
 858  *
 859  * Description:
 860  *     Records an action against a bio. Will log the bio offset + size.
 861  *
 862  **/
 863 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 864                               u32 what, int error)
 865 {
 866         struct blk_trace *bt = q->blk_trace;
 867
 868         if (likely(!bt))
 869                 return;
 870
 871         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
 872                         bio_op(bio), bio->bi_opf, what, error, 0, NULL,
 873                         blk_trace_bio_get_cgid(q, bio));
 874 }
 875
 876 static void blk_add_trace_bio_bounce(void *ignore,
 877                                      struct request_queue *q, struct bio *bio)
 878 {
 879         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
 880 }
 881
 882 static void blk_add_trace_bio_complete(void *ignore,
 883                                        struct request_queue *q, struct bio *bio,
 884                                        int error)
 885 {
 886         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
 887 }
 888
 889 static void blk_add_trace_bio_backmerge(void *ignore,
 890                                         struct request_queue *q,
 891                                         struct request *rq,
 892                                         struct bio *bio)
 893 {
 894         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
 895 }
 896
 897 static void blk_add_trace_bio_frontmerge(void *ignore,
 898                                          struct request_queue *q,
 899                                          struct request *rq,
 900                                          struct bio *bio)
 901 {
 902         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
 903 }
 904
 905 static void blk_add_trace_bio_queue(void *ignore,
 906                                     struct request_queue *q, struct bio *bio)
 907 {
 908         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
 909 }
 910
 911 static void blk_add_trace_getrq(void *ignore,
 912                                 struct request_queue *q,
 913                                 struct bio *bio, int rw)
 914 {
 915         if (bio)
 916                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
 917         else {
 918                 struct blk_trace *bt = q->blk_trace;
 919
 920                 if (bt)
 921                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_GETRQ, 0, 0,
 922                                         NULL, NULL);
 923         }
 924 }
 925
 926
 927 static void blk_add_trace_sleeprq(void *ignore,
 928                                   struct request_queue *q,
 929                                   struct bio *bio, int rw)
 930 {
 931         if (bio)
 932                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
 933         else {
 934                 struct blk_trace *bt = q->blk_trace;
 935
 936                 if (bt)
 937                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_SLEEPRQ,
 938                                         0, 0, NULL, NULL);
 939         }
 940 }
 941
 942 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 943 {
 944         struct blk_trace *bt = q->blk_trace;
 945
 946         if (bt)
 947                 __blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL, NULL);
 948 }
 949
 950 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 951                                     unsigned int depth, bool explicit)
 952 {
 953         struct blk_trace *bt = q->blk_trace;
 954
 955         if (bt) {
 956                 __be64 rpdu = cpu_to_be64(depth);
 957                 u32 what;
 958
 959                 if (explicit)
 960                         what = BLK_TA_UNPLUG_IO;
 961                 else
 962                         what = BLK_TA_UNPLUG_TIMER;
 963
 964                 __blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu, NULL);
 965         }
 966 }
 967
 968 static void blk_add_trace_split(void *ignore,
 969                                 struct request_queue *q, struct bio *bio,
 970                                 unsigned int pdu)
 971 {
 972         struct blk_trace *bt = q->blk_trace;
 973
 974         if (bt) {
 975                 __be64 rpdu = cpu_to_be64(pdu);
 976
 977                 __blk_add_trace(bt, bio->bi_iter.bi_sector,
 978                                 bio->bi_iter.bi_size, bio_op(bio), bio->bi_opf,
 979                                 BLK_TA_SPLIT, bio->bi_status, sizeof(rpdu),
 980                                 &rpdu, blk_trace_bio_get_cgid(q, bio));
 981         }
 982 }
 983
 984 /**
 985  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
 986  * @ignore:     trace callback data parameter (not used)
 987  * @q:          queue the io is for
 988  * @bio:        the source bio
 989  * @dev:        target device
 990  * @from:       source sector
 991  *
 992  * Description:
 993  *     Device mapper or raid target sometimes need to split a bio because
 994  *     it spans a stripe (or similar). Add a trace for that action.
 995  *
 996  **/
 997 static void blk_add_trace_bio_remap(void *ignore,
 998                                     struct request_queue *q, struct bio *bio,
 999                                     dev_t dev, sector_t from)
1000 {
1001         struct blk_trace *bt = q->blk_trace;
1002         struct blk_io_trace_remap r;
1003
1004         if (likely(!bt))
1005                 return;
1006
1007         r.device_from = cpu_to_be32(dev);
1008         r.device_to   = cpu_to_be32(bio_dev(bio));
1009         r.sector_from = cpu_to_be64(from);
1010
1011         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
1012                         bio_op(bio), bio->bi_opf, BLK_TA_REMAP, bio->bi_status,
1013                         sizeof(r), &r, blk_trace_bio_get_cgid(q, bio));
1014 }
1015
1016 /**
1017  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
1018  * @ignore:     trace callback data parameter (not used)
1019  * @q:          queue the io is for
1020  * @rq:         the source request
1021  * @dev:        target device
1022  * @from:       source sector
1023  *
1024  * Description:
1025  *     Device mapper remaps request to other devices.
1026  *     Add a trace for that action.
1027  *
1028  **/
1029 static void blk_add_trace_rq_remap(void *ignore,
1030                                    struct request_queue *q,
1031                                    struct request *rq, dev_t dev,
1032                                    sector_t from)
1033 {
1034         struct blk_trace *bt = q->blk_trace;
1035         struct blk_io_trace_remap r;
1036
1037         if (likely(!bt))
1038                 return;
1039
1040         r.device_from = cpu_to_be32(dev);
1041         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
1042         r.sector_from = cpu_to_be64(from);
1043
1044         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
1045                         rq_data_dir(rq), 0, BLK_TA_REMAP, 0,
1046                         sizeof(r), &r, blk_trace_request_get_cgid(q, rq));
1047 }
1048
1049 /**
1050  * blk_add_driver_data - Add binary message with driver-specific data
1051  * @q:          queue the io is for
1052  * @rq:         io request
1053  * @data:       driver-specific data
1054  * @len:        length of driver-specific data
1055  *
1056  * Description:
1057  *     Some drivers might want to write driver-specific data per request.
1058  *
1059  **/
1060 void blk_add_driver_data(struct request_queue *q,
1061                          struct request *rq,
1062                          void *data, size_t len)
1063 {
1064         struct blk_trace *bt = q->blk_trace;
1065
1066         if (likely(!bt))
1067                 return;
1068
1069         __blk_add_trace(bt, blk_rq_trace_sector(rq), blk_rq_bytes(rq), 0, 0,
1070                                 BLK_TA_DRV_DATA, 0, len, data,
1071                                 blk_trace_request_get_cgid(q, rq));
1072 }
1073 EXPORT_SYMBOL_GPL(blk_add_driver_data);
1074
1075 static void blk_register_tracepoints(void)
1076 {
1077         int ret;
1078
1079         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1080         WARN_ON(ret);
1081         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1082         WARN_ON(ret);
1083         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1084         WARN_ON(ret);
1085         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1086         WARN_ON(ret);
1087         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1088         WARN_ON(ret);
1089         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1090         WARN_ON(ret);
1091         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1092         WARN_ON(ret);
1093         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1094         WARN_ON(ret);
1095         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1096         WARN_ON(ret);
1097         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1098         WARN_ON(ret);
1099         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1100         WARN_ON(ret);
1101         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1102         WARN_ON(ret);
1103         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1104         WARN_ON(ret);
1105         ret = register_trace_block_split(blk_add_trace_split, NULL);
1106         WARN_ON(ret);
1107         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1108         WARN_ON(ret);
1109         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1110         WARN_ON(ret);
1111 }
1112
1113 static void blk_unregister_tracepoints(void)
1114 {
1115         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1116         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1117         unregister_trace_block_split(blk_add_trace_split, NULL);
1118         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1119         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1120         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1121         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1122         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1123         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1124         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1125         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1126         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1127         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1128         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1129         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1130         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1131
1132         tracepoint_synchronize_unregister();
1133 }
1134
1135 /*
1136  * struct blk_io_tracer formatting routines
1137  */
1138
1139 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1140 {
1141         int i = 0;
1142         int tc = t->action >> BLK_TC_SHIFT;
1143
1144         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1145                 rwbs[i++] = 'N';
1146                 goto out;
1147         }
1148
1149         if (tc & BLK_TC_FLUSH)
1150                 rwbs[i++] = 'F';
1151
1152         if (tc & BLK_TC_DISCARD)
1153                 rwbs[i++] = 'D';
1154         else if (tc & BLK_TC_WRITE)
1155                 rwbs[i++] = 'W';
1156         else if (t->bytes)
1157                 rwbs[i++] = 'R';
1158         else
1159                 rwbs[i++] = 'N';
1160
1161         if (tc & BLK_TC_FUA)
1162                 rwbs[i++] = 'F';
1163         if (tc & BLK_TC_AHEAD)
1164                 rwbs[i++] = 'A';
1165         if (tc & BLK_TC_SYNC)
1166                 rwbs[i++] = 'S';
1167         if (tc & BLK_TC_META)
1168                 rwbs[i++] = 'M';
1169 out:
1170         rwbs[i] = '\0';
1171 }
1172
1173 static inline
1174 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1175 {
1176         return (const struct blk_io_trace *)ent;
1177 }
1178
1179 static inline const void *pdu_start(const struct trace_entry *ent, bool has_cg)
1180 {
1181         return (void *)(te_blk_io_trace(ent) + 1) +
1182                 (has_cg ? sizeof(union kernfs_node_id) : 0);
1183 }
1184
1185 static inline const void *cgid_start(const struct trace_entry *ent)
1186 {
1187         return (void *)(te_blk_io_trace(ent) + 1);
1188 }
1189
1190 static inline int pdu_real_len(const struct trace_entry *ent, bool has_cg)
1191 {
1192         return te_blk_io_trace(ent)->pdu_len -
1193                         (has_cg ? sizeof(union kernfs_node_id) : 0);
1194 }
1195
1196 static inline u32 t_action(const struct trace_entry *ent)
1197 {
1198         return te_blk_io_trace(ent)->action;
1199 }
1200
1201 static inline u32 t_bytes(const struct trace_entry *ent)
1202 {
1203         return te_blk_io_trace(ent)->bytes;
1204 }
1205
1206 static inline u32 t_sec(const struct trace_entry *ent)
1207 {
1208         return te_blk_io_trace(ent)->bytes >> 9;
1209 }
1210
1211 static inline unsigned long long t_sector(const struct trace_entry *ent)
1212 {
1213         return te_blk_io_trace(ent)->sector;
1214 }
1215
1216 static inline __u16 t_error(const struct trace_entry *ent)
1217 {
1218         return te_blk_io_trace(ent)->error;
1219 }
1220
1221 static __u64 get_pdu_int(const struct trace_entry *ent, bool has_cg)
1222 {
1223         const __u64 *val = pdu_start(ent, has_cg);
1224         return be64_to_cpu(*val);
1225 }
1226
1227 static void get_pdu_remap(const struct trace_entry *ent,
1228                           struct blk_io_trace_remap *r, bool has_cg)
1229 {
1230         const struct blk_io_trace_remap *__r = pdu_start(ent, has_cg);
1231         __u64 sector_from = __r->sector_from;
1232
1233         r->device_from = be32_to_cpu(__r->device_from);
1234         r->device_to   = be32_to_cpu(__r->device_to);
1235         r->sector_from = be64_to_cpu(sector_from);
1236 }
1237
1238 typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act,
1239         bool has_cg);
1240
1241 static void blk_log_action_classic(struct trace_iterator *iter, const char *act,
1242         bool has_cg)
1243 {
1244         char rwbs[RWBS_LEN];
1245         unsigned long long ts  = iter->ts;
1246         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1247         unsigned secs          = (unsigned long)ts;
1248         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1249
1250         fill_rwbs(rwbs, t);
1251
1252         trace_seq_printf(&iter->seq,
1253                          "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1254                          MAJOR(t->device), MINOR(t->device), iter->cpu,
1255                          secs, nsec_rem, iter->ent->pid, act, rwbs);
1256 }
1257
1258 static void blk_log_action(struct trace_iterator *iter, const char *act,
1259         bool has_cg)
1260 {
1261         char rwbs[RWBS_LEN];
1262         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1263
1264         fill_rwbs(rwbs, t);
1265         if (has_cg) {
1266                 const union kernfs_node_id *id = cgid_start(iter->ent);
1267
1268                 if (blk_tracer_flags.val & TRACE_BLK_OPT_CGNAME) {
1269                         char blkcg_name_buf[NAME_MAX + 1] = "<...>";
1270
1271                         cgroup_path_from_kernfs_id(id, blkcg_name_buf,
1272                                 sizeof(blkcg_name_buf));
1273                         trace_seq_printf(&iter->seq, "%3d,%-3d %s %2s %3s ",
1274                                  MAJOR(t->device), MINOR(t->device),
1275                                  blkcg_name_buf, act, rwbs);
1276                 } else
1277                         trace_seq_printf(&iter->seq,
1278                                  "%3d,%-3d %x,%-x %2s %3s ",
1279                                  MAJOR(t->device), MINOR(t->device),
1280                                  id->ino, id->generation, act, rwbs);
1281         } else
1282                 trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1283                                  MAJOR(t->device), MINOR(t->device), act, rwbs);
1284 }
1285
1286 static void blk_log_dump_pdu(struct trace_seq *s,
1287         const struct trace_entry *ent, bool has_cg)
1288 {
1289         const unsigned char *pdu_buf;
1290         int pdu_len;
1291         int i, end;
1292
1293         pdu_buf = pdu_start(ent, has_cg);
1294         pdu_len = pdu_real_len(ent, has_cg);
1295
1296         if (!pdu_len)
1297                 return;
1298
1299         /* find the last zero that needs to be printed */
1300         for (end = pdu_len - 1; end >= 0; end--)
1301                 if (pdu_buf[end])
1302                         break;
1303         end++;
1304
1305         trace_seq_putc(s, '(');
1306
1307         for (i = 0; i < pdu_len; i++) {
1308
1309                 trace_seq_printf(s, "%s%02x",
1310                                  i == 0 ? "" : " ", pdu_buf[i]);
1311
1312                 /*
1313                  * stop when the rest is just zeroes and indicate so
1314                  * with a ".." appended
1315                  */
1316                 if (i == end && end != pdu_len - 1) {
1317                         trace_seq_puts(s, " ..) ");
1318                         return;
1319                 }
1320         }
1321
1322         trace_seq_puts(s, ") ");
1323 }
1324
1325 static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1326 {
1327         char cmd[TASK_COMM_LEN];
1328
1329         trace_find_cmdline(ent->pid, cmd);
1330
1331         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1332                 trace_seq_printf(s, "%u ", t_bytes(ent));
1333                 blk_log_dump_pdu(s, ent, has_cg);
1334                 trace_seq_printf(s, "[%s]\n", cmd);
1335         } else {
1336                 if (t_sec(ent))
1337                         trace_seq_printf(s, "%llu + %u [%s]\n",
1338                                                 t_sector(ent), t_sec(ent), cmd);
1339                 else
1340                         trace_seq_printf(s, "[%s]\n", cmd);
1341         }
1342 }
1343
1344 static void blk_log_with_error(struct trace_seq *s,
1345                               const struct trace_entry *ent, bool has_cg)
1346 {
1347         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1348                 blk_log_dump_pdu(s, ent, has_cg);
1349                 trace_seq_printf(s, "[%d]\n", t_error(ent));
1350         } else {
1351                 if (t_sec(ent))
1352                         trace_seq_printf(s, "%llu + %u [%d]\n",
1353                                          t_sector(ent),
1354                                          t_sec(ent), t_error(ent));
1355                 else
1356                         trace_seq_printf(s, "%llu [%d]\n",
1357                                          t_sector(ent), t_error(ent));
1358         }
1359 }
1360
1361 static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1362 {
1363         struct blk_io_trace_remap r = { .device_from = 0, };
1364
1365         get_pdu_remap(ent, &r, has_cg);
1366         trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1367                          t_sector(ent), t_sec(ent),
1368                          MAJOR(r.device_from), MINOR(r.device_from),
1369                          (unsigned long long)r.sector_from);
1370 }
1371
1372 static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1373 {
1374         char cmd[TASK_COMM_LEN];
1375
1376         trace_find_cmdline(ent->pid, cmd);
1377
1378         trace_seq_printf(s, "[%s]\n", cmd);
1379 }
1380
1381 static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1382 {
1383         char cmd[TASK_COMM_LEN];
1384
1385         trace_find_cmdline(ent->pid, cmd);
1386
1387         trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent, has_cg));
1388 }
1389
1390 static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1391 {
1392         char cmd[TASK_COMM_LEN];
1393
1394         trace_find_cmdline(ent->pid, cmd);
1395
1396         trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1397                          get_pdu_int(ent, has_cg), cmd);
1398 }
1399
1400 static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent,
1401                         bool has_cg)
1402 {
1403
1404         trace_seq_putmem(s, pdu_start(ent, has_cg),
1405                 pdu_real_len(ent, has_cg));
1406         trace_seq_putc(s, '\n');
1407 }
1408
1409 /*
1410  * struct tracer operations
1411  */
1412
1413 static void blk_tracer_print_header(struct seq_file *m)
1414 {
1415         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1416                 return;
1417         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1418                     "#  |     |     |           |   |   |\n");
1419 }
1420
1421 static void blk_tracer_start(struct trace_array *tr)
1422 {
1423         blk_tracer_enabled = true;
1424 }
1425
1426 static int blk_tracer_init(struct trace_array *tr)
1427 {
1428         blk_tr = tr;
1429         blk_tracer_start(tr);
1430         return 0;
1431 }
1432
1433 static void blk_tracer_stop(struct trace_array *tr)
1434 {
1435         blk_tracer_enabled = false;
1436 }
1437
1438 static void blk_tracer_reset(struct trace_array *tr)
1439 {
1440         blk_tracer_stop(tr);
1441 }
1442
1443 static const struct {
1444         const char *act[2];
1445         void       (*print)(struct trace_seq *s, const struct trace_entry *ent,
1446                             bool has_cg);
1447 } what2act[] = {
1448         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1449         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1450         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1451         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1452         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1453         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1454         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1455         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1456         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1457         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1458         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1459         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1460         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1461         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1462         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1463 };
1464
1465 static enum print_line_t print_one_line(struct trace_iterator *iter,
1466                                         bool classic)
1467 {
1468         struct trace_array *tr = iter->tr;
1469         struct trace_seq *s = &iter->seq;
1470         const struct blk_io_trace *t;
1471         u16 what;
1472         bool long_act;
1473         blk_log_action_t *log_action;
1474         bool has_cg;
1475
1476         t          = te_blk_io_trace(iter->ent);
1477         what       = (t->action & ((1 << BLK_TC_SHIFT) - 1)) & ~__BLK_TA_CGROUP;
1478         long_act   = !!(tr->trace_flags & TRACE_ITER_VERBOSE);
1479         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1480         has_cg     = t->action & __BLK_TA_CGROUP;
1481
1482         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1483                 log_action(iter, long_act ? "message" : "m", has_cg);
1484                 blk_log_msg(s, iter->ent, has_cg);
1485                 return trace_handle_return(s);
1486         }
1487
1488         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1489                 trace_seq_printf(s, "Unknown action %x\n", what);
1490         else {
1491                 log_action(iter, what2act[what].act[long_act], has_cg);
1492                 what2act[what].print(s, iter->ent, has_cg);
1493         }
1494
1495         return trace_handle_return(s);
1496 }
1497
1498 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1499                                                int flags, struct trace_event *event)
1500 {
1501         return print_one_line(iter, false);
1502 }
1503
1504 static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1505 {
1506         struct trace_seq *s = &iter->seq;
1507         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1508         const int offset = offsetof(struct blk_io_trace, sector);
1509         struct blk_io_trace old = {
1510                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1511                 .time     = iter->ts,
1512         };
1513
1514         trace_seq_putmem(s, &old, offset);
1515         trace_seq_putmem(s, &t->sector,
1516                          sizeof(old) - offset + t->pdu_len);
1517 }
1518
1519 static enum print_line_t
1520 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1521                              struct trace_event *event)
1522 {
1523         blk_trace_synthesize_old_trace(iter);
1524
1525         return trace_handle_return(&iter->seq);
1526 }
1527
1528 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1529 {
1530         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1531                 return TRACE_TYPE_UNHANDLED;
1532
1533         return print_one_line(iter, true);
1534 }
1535
1536 static int
1537 blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1538 {
1539         /* don't output context-info for blk_classic output */
1540         if (bit == TRACE_BLK_OPT_CLASSIC) {
1541                 if (set)
1542                         tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1543                 else
1544                         tr->trace_flags |= TRACE_ITER_CONTEXT_INFO;
1545         }
1546         return 0;
1547 }
1548
1549 static struct tracer blk_tracer __read_mostly = {
1550         .name           = "blk",
1551         .init           = blk_tracer_init,
1552         .reset          = blk_tracer_reset,
1553         .start          = blk_tracer_start,
1554         .stop           = blk_tracer_stop,
1555         .print_header   = blk_tracer_print_header,
1556         .print_line     = blk_tracer_print_line,
1557         .flags          = &blk_tracer_flags,
1558         .set_flag       = blk_tracer_set_flag,
1559 };
1560
1561 static struct trace_event_functions trace_blk_event_funcs = {
1562         .trace          = blk_trace_event_print,
1563         .binary         = blk_trace_event_print_binary,
1564 };
1565
1566 static struct trace_event trace_blk_event = {
1567         .type           = TRACE_BLK,
1568         .funcs          = &trace_blk_event_funcs,
1569 };
1570
1571 static int __init init_blk_tracer(void)
1572 {
1573         if (!register_trace_event(&trace_blk_event)) {
1574                 pr_warn("Warning: could not register block events\n");
1575                 return 1;
1576         }
1577
1578         if (register_tracer(&blk_tracer) != 0) {
1579                 pr_warn("Warning: could not register the block tracer\n");
1580                 unregister_trace_event(&trace_blk_event);
1581                 return 1;
1582         }
1583
1584         return 0;
1585 }
1586
1587 device_initcall(init_blk_tracer);
1588
1589 static int blk_trace_remove_queue(struct request_queue *q)
1590 {
1591         struct blk_trace *bt;
1592
1593         bt = xchg(&q->blk_trace, NULL);
1594         if (bt == NULL)
1595                 return -EINVAL;
1596
1597         put_probe_ref();
1598         blk_trace_free(bt);
1599         return 0;
1600 }
1601
1602 /*
1603  * Setup everything required to start tracing
1604  */
1605 static int blk_trace_setup_queue(struct request_queue *q,
1606                                  struct block_device *bdev)
1607 {
1608         struct blk_trace *bt = NULL;
1609         int ret = -ENOMEM;
1610
1611         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1612         if (!bt)
1613                 return -ENOMEM;
1614
1615         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1616         if (!bt->msg_data)
1617                 goto free_bt;
1618
1619         bt->dev = bdev->bd_dev;
1620         bt->act_mask = (u16)-1;
1621
1622         blk_trace_setup_lba(bt, bdev);
1623
1624         ret = -EBUSY;
1625         if (cmpxchg(&q->blk_trace, NULL, bt))
1626                 goto free_bt;
1627
1628         get_probe_ref();
1629         return 0;
1630
1631 free_bt:
1632         blk_trace_free(bt);
1633         return ret;
1634 }
1635
1636 /*
1637  * sysfs interface to enable and configure tracing
1638  */
1639
1640 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1641                                          struct device_attribute *attr,
1642                                          char *buf);
1643 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1644                                           struct device_attribute *attr,
1645                                           const char *buf, size_t count);
1646 #define BLK_TRACE_DEVICE_ATTR(_name) \
1647         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1648                     sysfs_blk_trace_attr_show, \
1649                     sysfs_blk_trace_attr_store)
1650
1651 static BLK_TRACE_DEVICE_ATTR(enable);
1652 static BLK_TRACE_DEVICE_ATTR(act_mask);
1653 static BLK_TRACE_DEVICE_ATTR(pid);
1654 static BLK_TRACE_DEVICE_ATTR(start_lba);
1655 static BLK_TRACE_DEVICE_ATTR(end_lba);
1656
1657 static struct attribute *blk_trace_attrs[] = {
1658         &dev_attr_enable.attr,
1659         &dev_attr_act_mask.attr,
1660         &dev_attr_pid.attr,
1661         &dev_attr_start_lba.attr,
1662         &dev_attr_end_lba.attr,
1663         NULL
1664 };
1665
1666 struct attribute_group blk_trace_attr_group = {
1667         .name  = "trace",
1668         .attrs = blk_trace_attrs,
1669 };
1670
1671 static const struct {
1672         int mask;
1673         const char *str;
1674 } mask_maps[] = {
1675         { BLK_TC_READ,          "read"          },
1676         { BLK_TC_WRITE,         "write"         },
1677         { BLK_TC_FLUSH,         "flush"         },
1678         { BLK_TC_SYNC,          "sync"          },
1679         { BLK_TC_QUEUE,         "queue"         },
1680         { BLK_TC_REQUEUE,       "requeue"       },
1681         { BLK_TC_ISSUE,         "issue"         },
1682         { BLK_TC_COMPLETE,      "complete"      },
1683         { BLK_TC_FS,            "fs"            },
1684         { BLK_TC_PC,            "pc"            },
1685         { BLK_TC_NOTIFY,        "notify"        },
1686         { BLK_TC_AHEAD,         "ahead"         },
1687         { BLK_TC_META,          "meta"          },
1688         { BLK_TC_DISCARD,       "discard"       },
1689         { BLK_TC_DRV_DATA,      "drv_data"      },
1690         { BLK_TC_FUA,           "fua"           },
1691 };
1692
1693 static int blk_trace_str2mask(const char *str)
1694 {
1695         int i;
1696         int mask = 0;
1697         char *buf, *s, *token;
1698
1699         buf = kstrdup(str, GFP_KERNEL);
1700         if (buf == NULL)
1701                 return -ENOMEM;
1702         s = strstrip(buf);
1703
1704         while (1) {
1705                 token = strsep(&s, ",");
1706                 if (token == NULL)
1707                         break;
1708
1709                 if (*token == '\0')
1710                         continue;
1711
1712                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1713                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1714                                 mask |= mask_maps[i].mask;
1715                                 break;
1716                         }
1717                 }
1718                 if (i == ARRAY_SIZE(mask_maps)) {
1719                         mask = -EINVAL;
1720                         break;
1721                 }
1722         }
1723         kfree(buf);
1724
1725         return mask;
1726 }
1727
1728 static ssize_t blk_trace_mask2str(char *buf, int mask)
1729 {
1730         int i;
1731         char *p = buf;
1732
1733         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1734                 if (mask & mask_maps[i].mask) {
1735                         p += sprintf(p, "%s%s",
1736                                     (p == buf) ? "" : ",", mask_maps[i].str);
1737                 }
1738         }
1739         *p++ = '\n';
1740
1741         return p - buf;
1742 }
1743
1744 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1745 {
1746         if (bdev->bd_disk == NULL)
1747                 return NULL;
1748
1749         return bdev_get_queue(bdev);
1750 }
1751
1752 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1753                                          struct device_attribute *attr,
1754                                          char *buf)
1755 {
1756         struct hd_struct *p = dev_to_part(dev);
1757         struct request_queue *q;
1758         struct block_device *bdev;
1759         ssize_t ret = -ENXIO;
1760
1761         bdev = bdget(part_devt(p));
1762         if (bdev == NULL)
1763                 goto out;
1764
1765         q = blk_trace_get_queue(bdev);
1766         if (q == NULL)
1767                 goto out_bdput;
1768
1769         mutex_lock(&q->blk_trace_mutex);
1770
1771         if (attr == &dev_attr_enable) {
1772                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1773                 goto out_unlock_bdev;
1774         }
1775
1776         if (q->blk_trace == NULL)
1777                 ret = sprintf(buf, "disabled\n");
1778         else if (attr == &dev_attr_act_mask)
1779                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1780         else if (attr == &dev_attr_pid)
1781                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1782         else if (attr == &dev_attr_start_lba)
1783                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1784         else if (attr == &dev_attr_end_lba)
1785                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1786
1787 out_unlock_bdev:
1788         mutex_unlock(&q->blk_trace_mutex);
1789 out_bdput:
1790         bdput(bdev);
1791 out:
1792         return ret;
1793 }
1794
1795 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1796                                           struct device_attribute *attr,
1797                                           const char *buf, size_t count)
1798 {
1799         struct block_device *bdev;
1800         struct request_queue *q;
1801         struct hd_struct *p;
1802         u64 value;
1803         ssize_t ret = -EINVAL;
1804
1805         if (count == 0)
1806                 goto out;
1807
1808         if (attr == &dev_attr_act_mask) {
1809                 if (kstrtoull(buf, 0, &value)) {
1810                         /* Assume it is a list of trace category names */
1811                         ret = blk_trace_str2mask(buf);
1812                         if (ret < 0)
1813                                 goto out;
1814                         value = ret;
1815                 }
1816         } else if (kstrtoull(buf, 0, &value))
1817                 goto out;
1818
1819         ret = -ENXIO;
1820
1821         p = dev_to_part(dev);
1822         bdev = bdget(part_devt(p));
1823         if (bdev == NULL)
1824                 goto out;
1825
1826         q = blk_trace_get_queue(bdev);
1827         if (q == NULL)
1828                 goto out_bdput;
1829
1830         mutex_lock(&q->blk_trace_mutex);
1831
1832         if (attr == &dev_attr_enable) {
1833                 if (!!value == !!q->blk_trace) {
1834                         ret = 0;
1835                         goto out_unlock_bdev;
1836                 }
1837                 if (value)
1838                         ret = blk_trace_setup_queue(q, bdev);
1839                 else
1840                         ret = blk_trace_remove_queue(q);
1841                 goto out_unlock_bdev;
1842         }
1843
1844         ret = 0;
1845         if (q->blk_trace == NULL)
1846                 ret = blk_trace_setup_queue(q, bdev);
1847
1848         if (ret == 0) {
1849                 if (attr == &dev_attr_act_mask)
1850                         q->blk_trace->act_mask = value;
1851                 else if (attr == &dev_attr_pid)
1852                         q->blk_trace->pid = value;
1853                 else if (attr == &dev_attr_start_lba)
1854                         q->blk_trace->start_lba = value;
1855                 else if (attr == &dev_attr_end_lba)
1856                         q->blk_trace->end_lba = value;
1857         }
1858
1859 out_unlock_bdev:
1860         mutex_unlock(&q->blk_trace_mutex);
1861 out_bdput:
1862         bdput(bdev);
1863 out:
1864         return ret ? ret : count;
1865 }
1866
1867 int blk_trace_init_sysfs(struct device *dev)
1868 {
1869         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1870 }
1871
1872 void blk_trace_remove_sysfs(struct device *dev)
1873 {
1874         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1875 }
1876
1877 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1878
1879 #ifdef CONFIG_EVENT_TRACING
1880
1881 void blk_fill_rwbs(char *rwbs, unsigned int op, int bytes)
1882 {
1883         int i = 0;
1884
1885         if (op & REQ_PREFLUSH)
1886                 rwbs[i++] = 'F';
1887
1888         switch (op & REQ_OP_MASK) {
1889         case REQ_OP_WRITE:
1890         case REQ_OP_WRITE_SAME:
1891                 rwbs[i++] = 'W';
1892                 break;
1893         case REQ_OP_DISCARD:
1894                 rwbs[i++] = 'D';
1895                 break;
1896         case REQ_OP_SECURE_ERASE:
1897                 rwbs[i++] = 'D';
1898                 rwbs[i++] = 'E';
1899                 break;
1900         case REQ_OP_FLUSH:
1901                 rwbs[i++] = 'F';
1902                 break;
1903         case REQ_OP_READ:
1904                 rwbs[i++] = 'R';
1905                 break;
1906         default:
1907                 rwbs[i++] = 'N';
1908         }
1909
1910         if (op & REQ_FUA)
1911                 rwbs[i++] = 'F';
1912         if (op & REQ_RAHEAD)
1913                 rwbs[i++] = 'A';
1914         if (op & REQ_SYNC)
1915                 rwbs[i++] = 'S';
1916         if (op & REQ_META)
1917                 rwbs[i++] = 'M';
1918
1919         rwbs[i] = '\0';
1920 }
1921 EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1922
1923 #endif /* CONFIG_EVENT_TRACING */
1924