kernel/trace/blktrace.c

   1 /*
   2  * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  16  *
  17  */
  18 #include <linux/kernel.h>
  19 #include <linux/blkdev.h>
  20 #include <linux/blktrace_api.h>
  21 #include <linux/percpu.h>
  22 #include <linux/init.h>
  23 #include <linux/mutex.h>
  24 #include <linux/slab.h>
  25 #include <linux/debugfs.h>
  26 #include <linux/export.h>
  27 #include <linux/time.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/list.h>
  30 #include <linux/blk-cgroup.h>
  31
  32 #include "../../block/blk.h"
  33
  34 #include <trace/events/block.h>
  35
  36 #include "trace_output.h"
  37
  38 #ifdef CONFIG_BLK_DEV_IO_TRACE
  39
  40 static unsigned int blktrace_seq __read_mostly = 1;
  41
  42 static struct trace_array *blk_tr;
  43 static bool blk_tracer_enabled __read_mostly;
  44
  45 static LIST_HEAD(running_trace_list);
  46 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock);
  47
  48 /* Select an alternative, minimalistic output than the original one */
  49 #define TRACE_BLK_OPT_CLASSIC   0x1
  50 #define TRACE_BLK_OPT_CGROUP    0x2
  51 #define TRACE_BLK_OPT_CGNAME    0x4
  52
  53 static struct tracer_opt blk_tracer_opts[] = {
  54         /* Default disable the minimalistic output */
  55         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
  56 #ifdef CONFIG_BLK_CGROUP
  57         { TRACER_OPT(blk_cgroup, TRACE_BLK_OPT_CGROUP) },
  58         { TRACER_OPT(blk_cgname, TRACE_BLK_OPT_CGNAME) },
  59 #endif
  60         { }
  61 };
  62
  63 static struct tracer_flags blk_tracer_flags = {
  64         .val  = 0,
  65         .opts = blk_tracer_opts,
  66 };
  67
  68 /* Global reference count of probes */
  69 static DEFINE_MUTEX(blk_probe_mutex);
  70 static int blk_probes_ref;
  71
  72 static void blk_register_tracepoints(void);
  73 static void blk_unregister_tracepoints(void);
  74
  75 /*
  76  * Send out a notify message.
  77  */
  78 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
  79                        const void *data, size_t len,
  80                        union kernfs_node_id *cgid)
  81 {
  82         struct blk_io_trace *t;
  83         struct ring_buffer_event *event = NULL;
  84         struct ring_buffer *buffer = NULL;
  85         int pc = 0;
  86         int cpu = smp_processor_id();
  87         bool blk_tracer = blk_tracer_enabled;
  88         ssize_t cgid_len = cgid ? sizeof(*cgid) : 0;
  89
  90         if (blk_tracer) {
  91                 buffer = blk_tr->trace_buffer.buffer;
  92                 pc = preempt_count();
  93                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
  94                                                   sizeof(*t) + len + cgid_len,
  95                                                   0, pc);
  96                 if (!event)
  97                         return;
  98                 t = ring_buffer_event_data(event);
  99                 goto record_it;
 100         }
 101
 102         if (!bt->rchan)
 103                 return;
 104
 105         t = relay_reserve(bt->rchan, sizeof(*t) + len + cgid_len);
 106         if (t) {
 107                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 108                 t->time = ktime_to_ns(ktime_get());
 109 record_it:
 110                 t->device = bt->dev;
 111                 t->action = action | (cgid ? __BLK_TN_CGROUP : 0);
 112                 t->pid = pid;
 113                 t->cpu = cpu;
 114                 t->pdu_len = len + cgid_len;
 115                 if (cgid)
 116                         memcpy((void *)t + sizeof(*t), cgid, cgid_len);
 117                 memcpy((void *) t + sizeof(*t) + cgid_len, data, len);
 118
 119                 if (blk_tracer)
 120                         trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
 121         }
 122 }
 123
 124 /*
 125  * Send out a notify for this process, if we haven't done so since a trace
 126  * started
 127  */
 128 static void trace_note_tsk(struct task_struct *tsk)
 129 {
 130         unsigned long flags;
 131         struct blk_trace *bt;
 132
 133         tsk->btrace_seq = blktrace_seq;
 134         spin_lock_irqsave(&running_trace_lock, flags);
 135         list_for_each_entry(bt, &running_trace_list, running_list) {
 136                 trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm,
 137                            sizeof(tsk->comm), NULL);
 138         }
 139         spin_unlock_irqrestore(&running_trace_lock, flags);
 140 }
 141
 142 static void trace_note_time(struct blk_trace *bt)
 143 {
 144         struct timespec64 now;
 145         unsigned long flags;
 146         u32 words[2];
 147
 148         /* need to check user space to see if this breaks in y2038 or y2106 */
 149         ktime_get_real_ts64(&now);
 150         words[0] = (u32)now.tv_sec;
 151         words[1] = now.tv_nsec;
 152
 153         local_irq_save(flags);
 154         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words), NULL);
 155         local_irq_restore(flags);
 156 }
 157
 158 void __trace_note_message(struct blk_trace *bt, struct blkcg *blkcg,
 159         const char *fmt, ...)
 160 {
 161         int n;
 162         va_list args;
 163         unsigned long flags;
 164         char *buf;
 165
 166         if (unlikely(bt->trace_state != Blktrace_running &&
 167                      !blk_tracer_enabled))
 168                 return;
 169
 170         /*
 171          * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
 172          * message to the trace.
 173          */
 174         if (!(bt->act_mask & BLK_TC_NOTIFY))
 175                 return;
 176
 177         local_irq_save(flags);
 178         buf = this_cpu_ptr(bt->msg_data);
 179         va_start(args, fmt);
 180         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 181         va_end(args);
 182
 183         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
 184                 blkcg = NULL;
 185 #ifdef CONFIG_BLK_CGROUP
 186         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n,
 187                 blkcg ? cgroup_get_kernfs_id(blkcg->css.cgroup) : NULL);
 188 #else
 189         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n, NULL);
 190 #endif
 191         local_irq_restore(flags);
 192 }
 193 EXPORT_SYMBOL_GPL(__trace_note_message);
 194
 195 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
 196                          pid_t pid)
 197 {
 198         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
 199                 return 1;
 200         if (sector && (sector < bt->start_lba || sector > bt->end_lba))
 201                 return 1;
 202         if (bt->pid && pid != bt->pid)
 203                 return 1;
 204
 205         return 0;
 206 }
 207
 208 /*
 209  * Data direction bit lookup
 210  */
 211 static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
 212                                  BLK_TC_ACT(BLK_TC_WRITE) };
 213
 214 #define BLK_TC_RAHEAD           BLK_TC_AHEAD
 215 #define BLK_TC_PREFLUSH         BLK_TC_FLUSH
 216
 217 /* The ilog2() calls fall out because they're constant */
 218 #define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
 219           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
 220
 221 /*
 222  * The worker for the various blk_add_trace*() types. Fills out a
 223  * blk_io_trace structure and places it in a per-cpu subbuffer.
 224  */
 225 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 226                      int op, int op_flags, u32 what, int error, int pdu_len,
 227                      void *pdu_data, union kernfs_node_id *cgid)
 228 {
 229         struct task_struct *tsk = current;
 230         struct ring_buffer_event *event = NULL;
 231         struct ring_buffer *buffer = NULL;
 232         struct blk_io_trace *t;
 233         unsigned long flags = 0;
 234         unsigned long *sequence;
 235         pid_t pid;
 236         int cpu, pc = 0;
 237         bool blk_tracer = blk_tracer_enabled;
 238         ssize_t cgid_len = cgid ? sizeof(*cgid) : 0;
 239
 240         if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
 241                 return;
 242
 243         what |= ddir_act[op_is_write(op) ? WRITE : READ];
 244         what |= MASK_TC_BIT(op_flags, SYNC);
 245         what |= MASK_TC_BIT(op_flags, RAHEAD);
 246         what |= MASK_TC_BIT(op_flags, META);
 247         what |= MASK_TC_BIT(op_flags, PREFLUSH);
 248         what |= MASK_TC_BIT(op_flags, FUA);
 249         if (op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE)
 250                 what |= BLK_TC_ACT(BLK_TC_DISCARD);
 251         if (op == REQ_OP_FLUSH)
 252                 what |= BLK_TC_ACT(BLK_TC_FLUSH);
 253         if (cgid)
 254                 what |= __BLK_TA_CGROUP;
 255
 256         pid = tsk->pid;
 257         if (act_log_check(bt, what, sector, pid))
 258                 return;
 259         cpu = raw_smp_processor_id();
 260
 261         if (blk_tracer) {
 262                 tracing_record_cmdline(current);
 263
 264                 buffer = blk_tr->trace_buffer.buffer;
 265                 pc = preempt_count();
 266                 event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
 267                                                   sizeof(*t) + pdu_len + cgid_len,
 268                                                   0, pc);
 269                 if (!event)
 270                         return;
 271                 t = ring_buffer_event_data(event);
 272                 goto record_it;
 273         }
 274
 275         if (unlikely(tsk->btrace_seq != blktrace_seq))
 276                 trace_note_tsk(tsk);
 277
 278         /*
 279          * A word about the locking here - we disable interrupts to reserve
 280          * some space in the relay per-cpu buffer, to prevent an irq
 281          * from coming in and stepping on our toes.
 282          */
 283         local_irq_save(flags);
 284         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len + cgid_len);
 285         if (t) {
 286                 sequence = per_cpu_ptr(bt->sequence, cpu);
 287
 288                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 289                 t->sequence = ++(*sequence);
 290                 t->time = ktime_to_ns(ktime_get());
 291 record_it:
 292                 /*
 293                  * These two are not needed in ftrace as they are in the
 294                  * generic trace_entry, filled by tracing_generic_entry_update,
 295                  * but for the trace_event->bin() synthesizer benefit we do it
 296                  * here too.
 297                  */
 298                 t->cpu = cpu;
 299                 t->pid = pid;
 300
 301                 t->sector = sector;
 302                 t->bytes = bytes;
 303                 t->action = what;
 304                 t->device = bt->dev;
 305                 t->error = error;
 306                 t->pdu_len = pdu_len + cgid_len;
 307
 308                 if (cgid_len)
 309                         memcpy((void *)t + sizeof(*t), cgid, cgid_len);
 310                 if (pdu_len)
 311                         memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len);
 312
 313                 if (blk_tracer) {
 314                         trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
 315                         return;
 316                 }
 317         }
 318
 319         local_irq_restore(flags);
 320 }
 321
 322 static void blk_trace_free(struct blk_trace *bt)
 323 {
 324         debugfs_remove(bt->msg_file);
 325         debugfs_remove(bt->dropped_file);
 326         relay_close(bt->rchan);
 327         debugfs_remove(bt->dir);
 328         free_percpu(bt->sequence);
 329         free_percpu(bt->msg_data);
 330         kfree(bt);
 331 }
 332
 333 static void get_probe_ref(void)
 334 {
 335         mutex_lock(&blk_probe_mutex);
 336         if (++blk_probes_ref == 1)
 337                 blk_register_tracepoints();
 338         mutex_unlock(&blk_probe_mutex);
 339 }
 340
 341 static void put_probe_ref(void)
 342 {
 343         mutex_lock(&blk_probe_mutex);
 344         if (!--blk_probes_ref)
 345                 blk_unregister_tracepoints();
 346         mutex_unlock(&blk_probe_mutex);
 347 }
 348
 349 static void blk_trace_cleanup(struct blk_trace *bt)
 350 {
 351         blk_trace_free(bt);
 352         put_probe_ref();
 353 }
 354
 355 static int __blk_trace_remove(struct request_queue *q)
 356 {
 357         struct blk_trace *bt;
 358
 359         bt = xchg(&q->blk_trace, NULL);
 360         if (!bt)
 361                 return -EINVAL;
 362
 363         if (bt->trace_state != Blktrace_running)
 364                 blk_trace_cleanup(bt);
 365
 366         return 0;
 367 }
 368
 369 int blk_trace_remove(struct request_queue *q)
 370 {
 371         int ret;
 372
 373         mutex_lock(&q->blk_trace_mutex);
 374         ret = __blk_trace_remove(q);
 375         mutex_unlock(&q->blk_trace_mutex);
 376
 377         return ret;
 378 }
 379 EXPORT_SYMBOL_GPL(blk_trace_remove);
 380
 381 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
 382                                 size_t count, loff_t *ppos)
 383 {
 384         struct blk_trace *bt = filp->private_data;
 385         char buf[16];
 386
 387         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
 388
 389         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 390 }
 391
 392 static const struct file_operations blk_dropped_fops = {
 393         .owner =        THIS_MODULE,
 394         .open =         simple_open,
 395         .read =         blk_dropped_read,
 396         .llseek =       default_llseek,
 397 };
 398
 399 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 400                                 size_t count, loff_t *ppos)
 401 {
 402         char *msg;
 403         struct blk_trace *bt;
 404
 405         if (count >= BLK_TN_MAX_MSG)
 406                 return -EINVAL;
 407
 408         msg = memdup_user_nul(buffer, count);
 409         if (IS_ERR(msg))
 410                 return PTR_ERR(msg);
 411
 412         bt = filp->private_data;
 413         __trace_note_message(bt, NULL, "%s", msg);
 414         kfree(msg);
 415
 416         return count;
 417 }
 418
 419 static const struct file_operations blk_msg_fops = {
 420         .owner =        THIS_MODULE,
 421         .open =         simple_open,
 422         .write =        blk_msg_write,
 423         .llseek =       noop_llseek,
 424 };
 425
 426 /*
 427  * Keep track of how many times we encountered a full subbuffer, to aid
 428  * the user space app in telling how many lost events there were.
 429  */
 430 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
 431                                      void *prev_subbuf, size_t prev_padding)
 432 {
 433         struct blk_trace *bt;
 434
 435         if (!relay_buf_full(buf))
 436                 return 1;
 437
 438         bt = buf->chan->private_data;
 439         atomic_inc(&bt->dropped);
 440         return 0;
 441 }
 442
 443 static int blk_remove_buf_file_callback(struct dentry *dentry)
 444 {
 445         debugfs_remove(dentry);
 446
 447         return 0;
 448 }
 449
 450 static struct dentry *blk_create_buf_file_callback(const char *filename,
 451                                                    struct dentry *parent,
 452                                                    umode_t mode,
 453                                                    struct rchan_buf *buf,
 454                                                    int *is_global)
 455 {
 456         return debugfs_create_file(filename, mode, parent, buf,
 457                                         &relay_file_operations);
 458 }
 459
 460 static struct rchan_callbacks blk_relay_callbacks = {
 461         .subbuf_start           = blk_subbuf_start_callback,
 462         .create_buf_file        = blk_create_buf_file_callback,
 463         .remove_buf_file        = blk_remove_buf_file_callback,
 464 };
 465
 466 static void blk_trace_setup_lba(struct blk_trace *bt,
 467                                 struct block_device *bdev)
 468 {
 469         struct hd_struct *part = NULL;
 470
 471         if (bdev)
 472                 part = bdev->bd_part;
 473
 474         if (part) {
 475                 bt->start_lba = part->start_sect;
 476                 bt->end_lba = part->start_sect + part->nr_sects;
 477         } else {
 478                 bt->start_lba = 0;
 479                 bt->end_lba = -1ULL;
 480         }
 481 }
 482
 483 /*
 484  * Setup everything required to start tracing
 485  */
 486 static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 487                               struct block_device *bdev,
 488                               struct blk_user_trace_setup *buts)
 489 {
 490         struct blk_trace *bt = NULL;
 491         struct dentry *dir = NULL;
 492         int ret;
 493
 494         if (!buts->buf_size || !buts->buf_nr)
 495                 return -EINVAL;
 496
 497         if (!blk_debugfs_root)
 498                 return -ENOENT;
 499
 500         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 501         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 502
 503         /*
 504          * some device names have larger paths - convert the slashes
 505          * to underscores for this to work as expected
 506          */
 507         strreplace(buts->name, '/', '_');
 508
 509         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 510         if (!bt)
 511                 return -ENOMEM;
 512
 513         ret = -ENOMEM;
 514         bt->sequence = alloc_percpu(unsigned long);
 515         if (!bt->sequence)
 516                 goto err;
 517
 518         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 519         if (!bt->msg_data)
 520                 goto err;
 521
 522         ret = -ENOENT;
 523
 524         dir = debugfs_lookup(buts->name, blk_debugfs_root);
 525         if (!dir)
 526                 bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);
 527         if (!dir)
 528                 goto err;
 529
 530         bt->dev = dev;
 531         atomic_set(&bt->dropped, 0);
 532         INIT_LIST_HEAD(&bt->running_list);
 533
 534         ret = -EIO;
 535         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 536                                                &blk_dropped_fops);
 537         if (!bt->dropped_file)
 538                 goto err;
 539
 540         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 541         if (!bt->msg_file)
 542                 goto err;
 543
 544         bt->rchan = relay_open("trace", dir, buts->buf_size,
 545                                 buts->buf_nr, &blk_relay_callbacks, bt);
 546         if (!bt->rchan)
 547                 goto err;
 548
 549         bt->act_mask = buts->act_mask;
 550         if (!bt->act_mask)
 551                 bt->act_mask = (u16) -1;
 552
 553         blk_trace_setup_lba(bt, bdev);
 554
 555         /* overwrite with user settings */
 556         if (buts->start_lba)
 557                 bt->start_lba = buts->start_lba;
 558         if (buts->end_lba)
 559                 bt->end_lba = buts->end_lba;
 560
 561         bt->pid = buts->pid;
 562         bt->trace_state = Blktrace_setup;
 563
 564         ret = -EBUSY;
 565         if (cmpxchg(&q->blk_trace, NULL, bt))
 566                 goto err;
 567
 568         get_probe_ref();
 569
 570         ret = 0;
 571 err:
 572         if (dir && !bt->dir)
 573                 dput(dir);
 574         if (ret)
 575                 blk_trace_free(bt);
 576         return ret;
 577 }
 578
 579 static int __blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 580                              struct block_device *bdev, char __user *arg)
 581 {
 582         struct blk_user_trace_setup buts;
 583         int ret;
 584
 585         ret = copy_from_user(&buts, arg, sizeof(buts));
 586         if (ret)
 587                 return -EFAULT;
 588
 589         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 590         if (ret)
 591                 return ret;
 592
 593         if (copy_to_user(arg, &buts, sizeof(buts))) {
 594                 __blk_trace_remove(q);
 595                 return -EFAULT;
 596         }
 597         return 0;
 598 }
 599
 600 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 601                     struct block_device *bdev,
 602                     char __user *arg)
 603 {
 604         int ret;
 605
 606         mutex_lock(&q->blk_trace_mutex);
 607         ret = __blk_trace_setup(q, name, dev, bdev, arg);
 608         mutex_unlock(&q->blk_trace_mutex);
 609
 610         return ret;
 611 }
 612 EXPORT_SYMBOL_GPL(blk_trace_setup);
 613
 614 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 615 static int compat_blk_trace_setup(struct request_queue *q, char *name,
 616                                   dev_t dev, struct block_device *bdev,
 617                                   char __user *arg)
 618 {
 619         struct blk_user_trace_setup buts;
 620         struct compat_blk_user_trace_setup cbuts;
 621         int ret;
 622
 623         if (copy_from_user(&cbuts, arg, sizeof(cbuts)))
 624                 return -EFAULT;
 625
 626         buts = (struct blk_user_trace_setup) {
 627                 .act_mask = cbuts.act_mask,
 628                 .buf_size = cbuts.buf_size,
 629                 .buf_nr = cbuts.buf_nr,
 630                 .start_lba = cbuts.start_lba,
 631                 .end_lba = cbuts.end_lba,
 632                 .pid = cbuts.pid,
 633         };
 634
 635         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
 636         if (ret)
 637                 return ret;
 638
 639         if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
 640                 __blk_trace_remove(q);
 641                 return -EFAULT;
 642         }
 643
 644         return 0;
 645 }
 646 #endif
 647
 648 static int __blk_trace_startstop(struct request_queue *q, int start)
 649 {
 650         int ret;
 651         struct blk_trace *bt = q->blk_trace;
 652
 653         if (bt == NULL)
 654                 return -EINVAL;
 655
 656         /*
 657          * For starting a trace, we can transition from a setup or stopped
 658          * trace. For stopping a trace, the state must be running
 659          */
 660         ret = -EINVAL;
 661         if (start) {
 662                 if (bt->trace_state == Blktrace_setup ||
 663                     bt->trace_state == Blktrace_stopped) {
 664                         blktrace_seq++;
 665                         smp_mb();
 666                         bt->trace_state = Blktrace_running;
 667                         spin_lock_irq(&running_trace_lock);
 668                         list_add(&bt->running_list, &running_trace_list);
 669                         spin_unlock_irq(&running_trace_lock);
 670
 671                         trace_note_time(bt);
 672                         ret = 0;
 673                 }
 674         } else {
 675                 if (bt->trace_state == Blktrace_running) {
 676                         bt->trace_state = Blktrace_stopped;
 677                         spin_lock_irq(&running_trace_lock);
 678                         list_del_init(&bt->running_list);
 679                         spin_unlock_irq(&running_trace_lock);
 680                         relay_flush(bt->rchan);
 681                         ret = 0;
 682                 }
 683         }
 684
 685         return ret;
 686 }
 687
 688 int blk_trace_startstop(struct request_queue *q, int start)
 689 {
 690         int ret;
 691
 692         mutex_lock(&q->blk_trace_mutex);
 693         ret = __blk_trace_startstop(q, start);
 694         mutex_unlock(&q->blk_trace_mutex);
 695
 696         return ret;
 697 }
 698 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 699
 700 /*
 701  * When reading or writing the blktrace sysfs files, the references to the
 702  * opened sysfs or device files should prevent the underlying block device
 703  * from being removed. So no further delete protection is really needed.
 704  */
 705
 706 /**
 707  * blk_trace_ioctl: - handle the ioctls associated with tracing
 708  * @bdev:       the block device
 709  * @cmd:        the ioctl cmd
 710  * @arg:        the argument data, if any
 711  *
 712  **/
 713 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 714 {
 715         struct request_queue *q;
 716         int ret, start = 0;
 717         char b[BDEVNAME_SIZE];
 718
 719         q = bdev_get_queue(bdev);
 720         if (!q)
 721                 return -ENXIO;
 722
 723         mutex_lock(&q->blk_trace_mutex);
 724
 725         switch (cmd) {
 726         case BLKTRACESETUP:
 727                 bdevname(bdev, b);
 728                 ret = __blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 729                 break;
 730 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 731         case BLKTRACESETUP32:
 732                 bdevname(bdev, b);
 733                 ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
 734                 break;
 735 #endif
 736         case BLKTRACESTART:
 737                 start = 1;
 738         case BLKTRACESTOP:
 739                 ret = __blk_trace_startstop(q, start);
 740                 break;
 741         case BLKTRACETEARDOWN:
 742                 ret = __blk_trace_remove(q);
 743                 break;
 744         default:
 745                 ret = -ENOTTY;
 746                 break;
 747         }
 748
 749         mutex_unlock(&q->blk_trace_mutex);
 750         return ret;
 751 }
 752
 753 /**
 754  * blk_trace_shutdown: - stop and cleanup trace structures
 755  * @q:    the request queue associated with the device
 756  *
 757  **/
 758 void blk_trace_shutdown(struct request_queue *q)
 759 {
 760         mutex_lock(&q->blk_trace_mutex);
 761
 762         if (q->blk_trace) {
 763                 __blk_trace_startstop(q, 0);
 764                 __blk_trace_remove(q);
 765         }
 766
 767         mutex_unlock(&q->blk_trace_mutex);
 768 }
 769
 770 #ifdef CONFIG_BLK_CGROUP
 771 static union kernfs_node_id *
 772 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 773 {
 774         struct blk_trace *bt = q->blk_trace;
 775
 776         if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
 777                 return NULL;
 778
 779         if (!bio->bi_css)
 780                 return NULL;
 781         return cgroup_get_kernfs_id(bio->bi_css->cgroup);
 782 }
 783 #else
 784 static union kernfs_node_id *
 785 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 786 {
 787         return NULL;
 788 }
 789 #endif
 790
 791 static union kernfs_node_id *
 792 blk_trace_request_get_cgid(struct request_queue *q, struct request *rq)
 793 {
 794         if (!rq->bio)
 795                 return NULL;
 796         /* Use the first bio */
 797         return blk_trace_bio_get_cgid(q, rq->bio);
 798 }
 799
 800 /*
 801  * blktrace probes
 802  */
 803
 804 /**
 805  * blk_add_trace_rq - Add a trace for a request oriented action
 806  * @rq:         the source request
 807  * @error:      return status to log
 808  * @nr_bytes:   number of completed bytes
 809  * @what:       the action
 810  * @cgid:       the cgroup info
 811  *
 812  * Description:
 813  *     Records an action against a request. Will log the bio offset + size.
 814  *
 815  **/
 816 static void blk_add_trace_rq(struct request *rq, int error,
 817                              unsigned int nr_bytes, u32 what,
 818                              union kernfs_node_id *cgid)
 819 {
 820         struct blk_trace *bt = rq->q->blk_trace;
 821
 822         if (likely(!bt))
 823                 return;
 824
 825         if (blk_rq_is_passthrough(rq))
 826                 what |= BLK_TC_ACT(BLK_TC_PC);
 827         else
 828                 what |= BLK_TC_ACT(BLK_TC_FS);
 829
 830         __blk_add_trace(bt, blk_rq_trace_sector(rq), nr_bytes, req_op(rq),
 831                         rq->cmd_flags, what, error, 0, NULL, cgid);
 832 }
 833
 834 static void blk_add_trace_rq_insert(void *ignore,
 835                                     struct request_queue *q, struct request *rq)
 836 {
 837         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_INSERT,
 838                          blk_trace_request_get_cgid(q, rq));
 839 }
 840
 841 static void blk_add_trace_rq_issue(void *ignore,
 842                                    struct request_queue *q, struct request *rq)
 843 {
 844         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_ISSUE,
 845                          blk_trace_request_get_cgid(q, rq));
 846 }
 847
 848 static void blk_add_trace_rq_requeue(void *ignore,
 849                                      struct request_queue *q,
 850                                      struct request *rq)
 851 {
 852         blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_REQUEUE,
 853                          blk_trace_request_get_cgid(q, rq));
 854 }
 855
 856 static void blk_add_trace_rq_complete(void *ignore, struct request *rq,
 857                         int error, unsigned int nr_bytes)
 858 {
 859         blk_add_trace_rq(rq, error, nr_bytes, BLK_TA_COMPLETE,
 860                          blk_trace_request_get_cgid(rq->q, rq));
 861 }
 862
 863 /**
 864  * blk_add_trace_bio - Add a trace for a bio oriented action
 865  * @q:          queue the io is for
 866  * @bio:        the source bio
 867  * @what:       the action
 868  * @error:      error, if any
 869  *
 870  * Description:
 871  *     Records an action against a bio. Will log the bio offset + size.
 872  *
 873  **/
 874 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 875                               u32 what, int error)
 876 {
 877         struct blk_trace *bt = q->blk_trace;
 878
 879         if (likely(!bt))
 880                 return;
 881
 882         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
 883                         bio_op(bio), bio->bi_opf, what, error, 0, NULL,
 884                         blk_trace_bio_get_cgid(q, bio));
 885 }
 886
 887 static void blk_add_trace_bio_bounce(void *ignore,
 888                                      struct request_queue *q, struct bio *bio)
 889 {
 890         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE, 0);
 891 }
 892
 893 static void blk_add_trace_bio_complete(void *ignore,
 894                                        struct request_queue *q, struct bio *bio,
 895                                        int error)
 896 {
 897         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE, error);
 898 }
 899
 900 static void blk_add_trace_bio_backmerge(void *ignore,
 901                                         struct request_queue *q,
 902                                         struct request *rq,
 903                                         struct bio *bio)
 904 {
 905         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE, 0);
 906 }
 907
 908 static void blk_add_trace_bio_frontmerge(void *ignore,
 909                                          struct request_queue *q,
 910                                          struct request *rq,
 911                                          struct bio *bio)
 912 {
 913         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE, 0);
 914 }
 915
 916 static void blk_add_trace_bio_queue(void *ignore,
 917                                     struct request_queue *q, struct bio *bio)
 918 {
 919         blk_add_trace_bio(q, bio, BLK_TA_QUEUE, 0);
 920 }
 921
 922 static void blk_add_trace_getrq(void *ignore,
 923                                 struct request_queue *q,
 924                                 struct bio *bio, int rw)
 925 {
 926         if (bio)
 927                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ, 0);
 928         else {
 929                 struct blk_trace *bt = q->blk_trace;
 930
 931                 if (bt)
 932                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_GETRQ, 0, 0,
 933                                         NULL, NULL);
 934         }
 935 }
 936
 937
 938 static void blk_add_trace_sleeprq(void *ignore,
 939                                   struct request_queue *q,
 940                                   struct bio *bio, int rw)
 941 {
 942         if (bio)
 943                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ, 0);
 944         else {
 945                 struct blk_trace *bt = q->blk_trace;
 946
 947                 if (bt)
 948                         __blk_add_trace(bt, 0, 0, rw, 0, BLK_TA_SLEEPRQ,
 949                                         0, 0, NULL, NULL);
 950         }
 951 }
 952
 953 static void blk_add_trace_plug(void *ignore, struct request_queue *q)
 954 {
 955         struct blk_trace *bt = q->blk_trace;
 956
 957         if (bt)
 958                 __blk_add_trace(bt, 0, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL, NULL);
 959 }
 960
 961 static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 962                                     unsigned int depth, bool explicit)
 963 {
 964         struct blk_trace *bt = q->blk_trace;
 965
 966         if (bt) {
 967                 __be64 rpdu = cpu_to_be64(depth);
 968                 u32 what;
 969
 970                 if (explicit)
 971                         what = BLK_TA_UNPLUG_IO;
 972                 else
 973                         what = BLK_TA_UNPLUG_TIMER;
 974
 975                 __blk_add_trace(bt, 0, 0, 0, 0, what, 0, sizeof(rpdu), &rpdu, NULL);
 976         }
 977 }
 978
 979 static void blk_add_trace_split(void *ignore,
 980                                 struct request_queue *q, struct bio *bio,
 981                                 unsigned int pdu)
 982 {
 983         struct blk_trace *bt = q->blk_trace;
 984
 985         if (bt) {
 986                 __be64 rpdu = cpu_to_be64(pdu);
 987
 988                 __blk_add_trace(bt, bio->bi_iter.bi_sector,
 989                                 bio->bi_iter.bi_size, bio_op(bio), bio->bi_opf,
 990                                 BLK_TA_SPLIT, bio->bi_status, sizeof(rpdu),
 991                                 &rpdu, blk_trace_bio_get_cgid(q, bio));
 992         }
 993 }
 994
 995 /**
 996  * blk_add_trace_bio_remap - Add a trace for a bio-remap operation
 997  * @ignore:     trace callback data parameter (not used)
 998  * @q:          queue the io is for
 999  * @bio:        the source bio
1000  * @dev:        target device
1001  * @from:       source sector
1002  *
1003  * Description:
1004  *     Device mapper or raid target sometimes need to split a bio because
1005  *     it spans a stripe (or similar). Add a trace for that action.
1006  *
1007  **/
1008 static void blk_add_trace_bio_remap(void *ignore,
1009                                     struct request_queue *q, struct bio *bio,
1010                                     dev_t dev, sector_t from)
1011 {
1012         struct blk_trace *bt = q->blk_trace;
1013         struct blk_io_trace_remap r;
1014
1015         if (likely(!bt))
1016                 return;
1017
1018         r.device_from = cpu_to_be32(dev);
1019         r.device_to   = cpu_to_be32(bio_dev(bio));
1020         r.sector_from = cpu_to_be64(from);
1021
1022         __blk_add_trace(bt, bio->bi_iter.bi_sector, bio->bi_iter.bi_size,
1023                         bio_op(bio), bio->bi_opf, BLK_TA_REMAP, bio->bi_status,
1024                         sizeof(r), &r, blk_trace_bio_get_cgid(q, bio));
1025 }
1026
1027 /**
1028  * blk_add_trace_rq_remap - Add a trace for a request-remap operation
1029  * @ignore:     trace callback data parameter (not used)
1030  * @q:          queue the io is for
1031  * @rq:         the source request
1032  * @dev:        target device
1033  * @from:       source sector
1034  *
1035  * Description:
1036  *     Device mapper remaps request to other devices.
1037  *     Add a trace for that action.
1038  *
1039  **/
1040 static void blk_add_trace_rq_remap(void *ignore,
1041                                    struct request_queue *q,
1042                                    struct request *rq, dev_t dev,
1043                                    sector_t from)
1044 {
1045         struct blk_trace *bt = q->blk_trace;
1046         struct blk_io_trace_remap r;
1047
1048         if (likely(!bt))
1049                 return;
1050
1051         r.device_from = cpu_to_be32(dev);
1052         r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));
1053         r.sector_from = cpu_to_be64(from);
1054
1055         __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
1056                         rq_data_dir(rq), 0, BLK_TA_REMAP, 0,
1057                         sizeof(r), &r, blk_trace_request_get_cgid(q, rq));
1058 }
1059
1060 /**
1061  * blk_add_driver_data - Add binary message with driver-specific data
1062  * @q:          queue the io is for
1063  * @rq:         io request
1064  * @data:       driver-specific data
1065  * @len:        length of driver-specific data
1066  *
1067  * Description:
1068  *     Some drivers might want to write driver-specific data per request.
1069  *
1070  **/
1071 void blk_add_driver_data(struct request_queue *q,
1072                          struct request *rq,
1073                          void *data, size_t len)
1074 {
1075         struct blk_trace *bt = q->blk_trace;
1076
1077         if (likely(!bt))
1078                 return;
1079
1080         __blk_add_trace(bt, blk_rq_trace_sector(rq), blk_rq_bytes(rq), 0, 0,
1081                                 BLK_TA_DRV_DATA, 0, len, data,
1082                                 blk_trace_request_get_cgid(q, rq));
1083 }
1084 EXPORT_SYMBOL_GPL(blk_add_driver_data);
1085
1086 static void blk_register_tracepoints(void)
1087 {
1088         int ret;
1089
1090         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1091         WARN_ON(ret);
1092         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1093         WARN_ON(ret);
1094         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1095         WARN_ON(ret);
1096         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1097         WARN_ON(ret);
1098         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1099         WARN_ON(ret);
1100         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1101         WARN_ON(ret);
1102         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1103         WARN_ON(ret);
1104         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1105         WARN_ON(ret);
1106         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1107         WARN_ON(ret);
1108         ret = register_trace_block_getrq(blk_add_trace_getrq, NULL);
1109         WARN_ON(ret);
1110         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1111         WARN_ON(ret);
1112         ret = register_trace_block_plug(blk_add_trace_plug, NULL);
1113         WARN_ON(ret);
1114         ret = register_trace_block_unplug(blk_add_trace_unplug, NULL);
1115         WARN_ON(ret);
1116         ret = register_trace_block_split(blk_add_trace_split, NULL);
1117         WARN_ON(ret);
1118         ret = register_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1119         WARN_ON(ret);
1120         ret = register_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1121         WARN_ON(ret);
1122 }
1123
1124 static void blk_unregister_tracepoints(void)
1125 {
1126         unregister_trace_block_rq_remap(blk_add_trace_rq_remap, NULL);
1127         unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
1128         unregister_trace_block_split(blk_add_trace_split, NULL);
1129         unregister_trace_block_unplug(blk_add_trace_unplug, NULL);
1130         unregister_trace_block_plug(blk_add_trace_plug, NULL);
1131         unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
1132         unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
1133         unregister_trace_block_bio_queue(blk_add_trace_bio_queue, NULL);
1134         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge, NULL);
1135         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge, NULL);
1136         unregister_trace_block_bio_complete(blk_add_trace_bio_complete, NULL);
1137         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL);
1138         unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL);
1139         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL);
1140         unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL);
1141         unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL);
1142
1143         tracepoint_synchronize_unregister();
1144 }
1145
1146 /*
1147  * struct blk_io_tracer formatting routines
1148  */
1149
1150 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1151 {
1152         int i = 0;
1153         int tc = t->action >> BLK_TC_SHIFT;
1154
1155         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1156                 rwbs[i++] = 'N';
1157                 goto out;
1158         }
1159
1160         if (tc & BLK_TC_FLUSH)
1161                 rwbs[i++] = 'F';
1162
1163         if (tc & BLK_TC_DISCARD)
1164                 rwbs[i++] = 'D';
1165         else if (tc & BLK_TC_WRITE)
1166                 rwbs[i++] = 'W';
1167         else if (t->bytes)
1168                 rwbs[i++] = 'R';
1169         else
1170                 rwbs[i++] = 'N';
1171
1172         if (tc & BLK_TC_FUA)
1173                 rwbs[i++] = 'F';
1174         if (tc & BLK_TC_AHEAD)
1175                 rwbs[i++] = 'A';
1176         if (tc & BLK_TC_SYNC)
1177                 rwbs[i++] = 'S';
1178         if (tc & BLK_TC_META)
1179                 rwbs[i++] = 'M';
1180 out:
1181         rwbs[i] = '\0';
1182 }
1183
1184 static inline
1185 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1186 {
1187         return (const struct blk_io_trace *)ent;
1188 }
1189
1190 static inline const void *pdu_start(const struct trace_entry *ent, bool has_cg)
1191 {
1192         return (void *)(te_blk_io_trace(ent) + 1) +
1193                 (has_cg ? sizeof(union kernfs_node_id) : 0);
1194 }
1195
1196 static inline const void *cgid_start(const struct trace_entry *ent)
1197 {
1198         return (void *)(te_blk_io_trace(ent) + 1);
1199 }
1200
1201 static inline int pdu_real_len(const struct trace_entry *ent, bool has_cg)
1202 {
1203         return te_blk_io_trace(ent)->pdu_len -
1204                         (has_cg ? sizeof(union kernfs_node_id) : 0);
1205 }
1206
1207 static inline u32 t_action(const struct trace_entry *ent)
1208 {
1209         return te_blk_io_trace(ent)->action;
1210 }
1211
1212 static inline u32 t_bytes(const struct trace_entry *ent)
1213 {
1214         return te_blk_io_trace(ent)->bytes;
1215 }
1216
1217 static inline u32 t_sec(const struct trace_entry *ent)
1218 {
1219         return te_blk_io_trace(ent)->bytes >> 9;
1220 }
1221
1222 static inline unsigned long long t_sector(const struct trace_entry *ent)
1223 {
1224         return te_blk_io_trace(ent)->sector;
1225 }
1226
1227 static inline __u16 t_error(const struct trace_entry *ent)
1228 {
1229         return te_blk_io_trace(ent)->error;
1230 }
1231
1232 static __u64 get_pdu_int(const struct trace_entry *ent, bool has_cg)
1233 {
1234         const __u64 *val = pdu_start(ent, has_cg);
1235         return be64_to_cpu(*val);
1236 }
1237
1238 static void get_pdu_remap(const struct trace_entry *ent,
1239                           struct blk_io_trace_remap *r, bool has_cg)
1240 {
1241         const struct blk_io_trace_remap *__r = pdu_start(ent, has_cg);
1242         __u64 sector_from = __r->sector_from;
1243
1244         r->device_from = be32_to_cpu(__r->device_from);
1245         r->device_to   = be32_to_cpu(__r->device_to);
1246         r->sector_from = be64_to_cpu(sector_from);
1247 }
1248
1249 typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act,
1250         bool has_cg);
1251
1252 static void blk_log_action_classic(struct trace_iterator *iter, const char *act,
1253         bool has_cg)
1254 {
1255         char rwbs[RWBS_LEN];
1256         unsigned long long ts  = iter->ts;
1257         unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1258         unsigned secs          = (unsigned long)ts;
1259         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1260
1261         fill_rwbs(rwbs, t);
1262
1263         trace_seq_printf(&iter->seq,
1264                          "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1265                          MAJOR(t->device), MINOR(t->device), iter->cpu,
1266                          secs, nsec_rem, iter->ent->pid, act, rwbs);
1267 }
1268
1269 static void blk_log_action(struct trace_iterator *iter, const char *act,
1270         bool has_cg)
1271 {
1272         char rwbs[RWBS_LEN];
1273         const struct blk_io_trace *t = te_blk_io_trace(iter->ent);
1274
1275         fill_rwbs(rwbs, t);
1276         if (has_cg) {
1277                 const union kernfs_node_id *id = cgid_start(iter->ent);
1278
1279                 if (blk_tracer_flags.val & TRACE_BLK_OPT_CGNAME) {
1280                         char blkcg_name_buf[NAME_MAX + 1] = "<...>";
1281
1282                         cgroup_path_from_kernfs_id(id, blkcg_name_buf,
1283                                 sizeof(blkcg_name_buf));
1284                         trace_seq_printf(&iter->seq, "%3d,%-3d %s %2s %3s ",
1285                                  MAJOR(t->device), MINOR(t->device),
1286                                  blkcg_name_buf, act, rwbs);
1287                 } else
1288                         trace_seq_printf(&iter->seq,
1289                                  "%3d,%-3d %x,%-x %2s %3s ",
1290                                  MAJOR(t->device), MINOR(t->device),
1291                                  id->ino, id->generation, act, rwbs);
1292         } else
1293                 trace_seq_printf(&iter->seq, "%3d,%-3d %2s %3s ",
1294                                  MAJOR(t->device), MINOR(t->device), act, rwbs);
1295 }
1296
1297 static void blk_log_dump_pdu(struct trace_seq *s,
1298         const struct trace_entry *ent, bool has_cg)
1299 {
1300         const unsigned char *pdu_buf;
1301         int pdu_len;
1302         int i, end;
1303
1304         pdu_buf = pdu_start(ent, has_cg);
1305         pdu_len = pdu_real_len(ent, has_cg);
1306
1307         if (!pdu_len)
1308                 return;
1309
1310         /* find the last zero that needs to be printed */
1311         for (end = pdu_len - 1; end >= 0; end--)
1312                 if (pdu_buf[end])
1313                         break;
1314         end++;
1315
1316         trace_seq_putc(s, '(');
1317
1318         for (i = 0; i < pdu_len; i++) {
1319
1320                 trace_seq_printf(s, "%s%02x",
1321                                  i == 0 ? "" : " ", pdu_buf[i]);
1322
1323                 /*
1324                  * stop when the rest is just zeroes and indicate so
1325                  * with a ".." appended
1326                  */
1327                 if (i == end && end != pdu_len - 1) {
1328                         trace_seq_puts(s, " ..) ");
1329                         return;
1330                 }
1331         }
1332
1333         trace_seq_puts(s, ") ");
1334 }
1335
1336 static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1337 {
1338         char cmd[TASK_COMM_LEN];
1339
1340         trace_find_cmdline(ent->pid, cmd);
1341
1342         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1343                 trace_seq_printf(s, "%u ", t_bytes(ent));
1344                 blk_log_dump_pdu(s, ent, has_cg);
1345                 trace_seq_printf(s, "[%s]\n", cmd);
1346         } else {
1347                 if (t_sec(ent))
1348                         trace_seq_printf(s, "%llu + %u [%s]\n",
1349                                                 t_sector(ent), t_sec(ent), cmd);
1350                 else
1351                         trace_seq_printf(s, "[%s]\n", cmd);
1352         }
1353 }
1354
1355 static void blk_log_with_error(struct trace_seq *s,
1356                               const struct trace_entry *ent, bool has_cg)
1357 {
1358         if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1359                 blk_log_dump_pdu(s, ent, has_cg);
1360                 trace_seq_printf(s, "[%d]\n", t_error(ent));
1361         } else {
1362                 if (t_sec(ent))
1363                         trace_seq_printf(s, "%llu + %u [%d]\n",
1364                                          t_sector(ent),
1365                                          t_sec(ent), t_error(ent));
1366                 else
1367                         trace_seq_printf(s, "%llu [%d]\n",
1368                                          t_sector(ent), t_error(ent));
1369         }
1370 }
1371
1372 static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1373 {
1374         struct blk_io_trace_remap r = { .device_from = 0, };
1375
1376         get_pdu_remap(ent, &r, has_cg);
1377         trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1378                          t_sector(ent), t_sec(ent),
1379                          MAJOR(r.device_from), MINOR(r.device_from),
1380                          (unsigned long long)r.sector_from);
1381 }
1382
1383 static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1384 {
1385         char cmd[TASK_COMM_LEN];
1386
1387         trace_find_cmdline(ent->pid, cmd);
1388
1389         trace_seq_printf(s, "[%s]\n", cmd);
1390 }
1391
1392 static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1393 {
1394         char cmd[TASK_COMM_LEN];
1395
1396         trace_find_cmdline(ent->pid, cmd);
1397
1398         trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent, has_cg));
1399 }
1400
1401 static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1402 {
1403         char cmd[TASK_COMM_LEN];
1404
1405         trace_find_cmdline(ent->pid, cmd);
1406
1407         trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1408                          get_pdu_int(ent, has_cg), cmd);
1409 }
1410
1411 static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent,
1412                         bool has_cg)
1413 {
1414
1415         trace_seq_putmem(s, pdu_start(ent, has_cg),
1416                 pdu_real_len(ent, has_cg));
1417         trace_seq_putc(s, '\n');
1418 }
1419
1420 /*
1421  * struct tracer operations
1422  */
1423
1424 static void blk_tracer_print_header(struct seq_file *m)
1425 {
1426         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1427                 return;
1428         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1429                     "#  |     |     |           |   |   |\n");
1430 }
1431
1432 static void blk_tracer_start(struct trace_array *tr)
1433 {
1434         blk_tracer_enabled = true;
1435 }
1436
1437 static int blk_tracer_init(struct trace_array *tr)
1438 {
1439         blk_tr = tr;
1440         blk_tracer_start(tr);
1441         return 0;
1442 }
1443
1444 static void blk_tracer_stop(struct trace_array *tr)
1445 {
1446         blk_tracer_enabled = false;
1447 }
1448
1449 static void blk_tracer_reset(struct trace_array *tr)
1450 {
1451         blk_tracer_stop(tr);
1452 }
1453
1454 static const struct {
1455         const char *act[2];
1456         void       (*print)(struct trace_seq *s, const struct trace_entry *ent,
1457                             bool has_cg);
1458 } what2act[] = {
1459         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1460         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1461         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1462         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1463         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1464         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1465         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1466         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1467         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1468         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1469         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1470         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1471         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1472         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1473         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1474 };
1475
1476 static enum print_line_t print_one_line(struct trace_iterator *iter,
1477                                         bool classic)
1478 {
1479         struct trace_array *tr = iter->tr;
1480         struct trace_seq *s = &iter->seq;
1481         const struct blk_io_trace *t;
1482         u16 what;
1483         bool long_act;
1484         blk_log_action_t *log_action;
1485         bool has_cg;
1486
1487         t          = te_blk_io_trace(iter->ent);
1488         what       = (t->action & ((1 << BLK_TC_SHIFT) - 1)) & ~__BLK_TA_CGROUP;
1489         long_act   = !!(tr->trace_flags & TRACE_ITER_VERBOSE);
1490         log_action = classic ? &blk_log_action_classic : &blk_log_action;
1491         has_cg     = t->action & __BLK_TA_CGROUP;
1492
1493         if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1494                 log_action(iter, long_act ? "message" : "m", has_cg);
1495                 blk_log_msg(s, iter->ent, has_cg);
1496                 return trace_handle_return(s);
1497         }
1498
1499         if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1500                 trace_seq_printf(s, "Unknown action %x\n", what);
1501         else {
1502                 log_action(iter, what2act[what].act[long_act], has_cg);
1503                 what2act[what].print(s, iter->ent, has_cg);
1504         }
1505
1506         return trace_handle_return(s);
1507 }
1508
1509 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1510                                                int flags, struct trace_event *event)
1511 {
1512         return print_one_line(iter, false);
1513 }
1514
1515 static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1516 {
1517         struct trace_seq *s = &iter->seq;
1518         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1519         const int offset = offsetof(struct blk_io_trace, sector);
1520         struct blk_io_trace old = {
1521                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1522                 .time     = iter->ts,
1523         };
1524
1525         trace_seq_putmem(s, &old, offset);
1526         trace_seq_putmem(s, &t->sector,
1527                          sizeof(old) - offset + t->pdu_len);
1528 }
1529
1530 static enum print_line_t
1531 blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1532                              struct trace_event *event)
1533 {
1534         blk_trace_synthesize_old_trace(iter);
1535
1536         return trace_handle_return(&iter->seq);
1537 }
1538
1539 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1540 {
1541         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1542                 return TRACE_TYPE_UNHANDLED;
1543
1544         return print_one_line(iter, true);
1545 }
1546
1547 static int
1548 blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1549 {
1550         /* don't output context-info for blk_classic output */
1551         if (bit == TRACE_BLK_OPT_CLASSIC) {
1552                 if (set)
1553                         tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1554                 else
1555                         tr->trace_flags |= TRACE_ITER_CONTEXT_INFO;
1556         }
1557         return 0;
1558 }
1559
1560 static struct tracer blk_tracer __read_mostly = {
1561         .name           = "blk",
1562         .init           = blk_tracer_init,
1563         .reset          = blk_tracer_reset,
1564         .start          = blk_tracer_start,
1565         .stop           = blk_tracer_stop,
1566         .print_header   = blk_tracer_print_header,
1567         .print_line     = blk_tracer_print_line,
1568         .flags          = &blk_tracer_flags,
1569         .set_flag       = blk_tracer_set_flag,
1570 };
1571
1572 static struct trace_event_functions trace_blk_event_funcs = {
1573         .trace          = blk_trace_event_print,
1574         .binary         = blk_trace_event_print_binary,
1575 };
1576
1577 static struct trace_event trace_blk_event = {
1578         .type           = TRACE_BLK,
1579         .funcs          = &trace_blk_event_funcs,
1580 };
1581
1582 static int __init init_blk_tracer(void)
1583 {
1584         if (!register_trace_event(&trace_blk_event)) {
1585                 pr_warn("Warning: could not register block events\n");
1586                 return 1;
1587         }
1588
1589         if (register_tracer(&blk_tracer) != 0) {
1590                 pr_warn("Warning: could not register the block tracer\n");
1591                 unregister_trace_event(&trace_blk_event);
1592                 return 1;
1593         }
1594
1595         return 0;
1596 }
1597
1598 device_initcall(init_blk_tracer);
1599
1600 static int blk_trace_remove_queue(struct request_queue *q)
1601 {
1602         struct blk_trace *bt;
1603
1604         bt = xchg(&q->blk_trace, NULL);
1605         if (bt == NULL)
1606                 return -EINVAL;
1607
1608         put_probe_ref();
1609         blk_trace_free(bt);
1610         return 0;
1611 }
1612
1613 /*
1614  * Setup everything required to start tracing
1615  */
1616 static int blk_trace_setup_queue(struct request_queue *q,
1617                                  struct block_device *bdev)
1618 {
1619         struct blk_trace *bt = NULL;
1620         int ret = -ENOMEM;
1621
1622         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1623         if (!bt)
1624                 return -ENOMEM;
1625
1626         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
1627         if (!bt->msg_data)
1628                 goto free_bt;
1629
1630         bt->dev = bdev->bd_dev;
1631         bt->act_mask = (u16)-1;
1632
1633         blk_trace_setup_lba(bt, bdev);
1634
1635         ret = -EBUSY;
1636         if (cmpxchg(&q->blk_trace, NULL, bt))
1637                 goto free_bt;
1638
1639         get_probe_ref();
1640         return 0;
1641
1642 free_bt:
1643         blk_trace_free(bt);
1644         return ret;
1645 }
1646
1647 /*
1648  * sysfs interface to enable and configure tracing
1649  */
1650
1651 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1652                                          struct device_attribute *attr,
1653                                          char *buf);
1654 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1655                                           struct device_attribute *attr,
1656                                           const char *buf, size_t count);
1657 #define BLK_TRACE_DEVICE_ATTR(_name) \
1658         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1659                     sysfs_blk_trace_attr_show, \
1660                     sysfs_blk_trace_attr_store)
1661
1662 static BLK_TRACE_DEVICE_ATTR(enable);
1663 static BLK_TRACE_DEVICE_ATTR(act_mask);
1664 static BLK_TRACE_DEVICE_ATTR(pid);
1665 static BLK_TRACE_DEVICE_ATTR(start_lba);
1666 static BLK_TRACE_DEVICE_ATTR(end_lba);
1667
1668 static struct attribute *blk_trace_attrs[] = {
1669         &dev_attr_enable.attr,
1670         &dev_attr_act_mask.attr,
1671         &dev_attr_pid.attr,
1672         &dev_attr_start_lba.attr,
1673         &dev_attr_end_lba.attr,
1674         NULL
1675 };
1676
1677 struct attribute_group blk_trace_attr_group = {
1678         .name  = "trace",
1679         .attrs = blk_trace_attrs,
1680 };
1681
1682 static const struct {
1683         int mask;
1684         const char *str;
1685 } mask_maps[] = {
1686         { BLK_TC_READ,          "read"          },
1687         { BLK_TC_WRITE,         "write"         },
1688         { BLK_TC_FLUSH,         "flush"         },
1689         { BLK_TC_SYNC,          "sync"          },
1690         { BLK_TC_QUEUE,         "queue"         },
1691         { BLK_TC_REQUEUE,       "requeue"       },
1692         { BLK_TC_ISSUE,         "issue"         },
1693         { BLK_TC_COMPLETE,      "complete"      },
1694         { BLK_TC_FS,            "fs"            },
1695         { BLK_TC_PC,            "pc"            },
1696         { BLK_TC_NOTIFY,        "notify"        },
1697         { BLK_TC_AHEAD,         "ahead"         },
1698         { BLK_TC_META,          "meta"          },
1699         { BLK_TC_DISCARD,       "discard"       },
1700         { BLK_TC_DRV_DATA,      "drv_data"      },
1701         { BLK_TC_FUA,           "fua"           },
1702 };
1703
1704 static int blk_trace_str2mask(const char *str)
1705 {
1706         int i;
1707         int mask = 0;
1708         char *buf, *s, *token;
1709
1710         buf = kstrdup(str, GFP_KERNEL);
1711         if (buf == NULL)
1712                 return -ENOMEM;
1713         s = strstrip(buf);
1714
1715         while (1) {
1716                 token = strsep(&s, ",");
1717                 if (token == NULL)
1718                         break;
1719
1720                 if (*token == '\0')
1721                         continue;
1722
1723                 for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1724                         if (strcasecmp(token, mask_maps[i].str) == 0) {
1725                                 mask |= mask_maps[i].mask;
1726                                 break;
1727                         }
1728                 }
1729                 if (i == ARRAY_SIZE(mask_maps)) {
1730                         mask = -EINVAL;
1731                         break;
1732                 }
1733         }
1734         kfree(buf);
1735
1736         return mask;
1737 }
1738
1739 static ssize_t blk_trace_mask2str(char *buf, int mask)
1740 {
1741         int i;
1742         char *p = buf;
1743
1744         for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1745                 if (mask & mask_maps[i].mask) {
1746                         p += sprintf(p, "%s%s",
1747                                     (p == buf) ? "" : ",", mask_maps[i].str);
1748                 }
1749         }
1750         *p++ = '\n';
1751
1752         return p - buf;
1753 }
1754
1755 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1756 {
1757         if (bdev->bd_disk == NULL)
1758                 return NULL;
1759
1760         return bdev_get_queue(bdev);
1761 }
1762
1763 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1764                                          struct device_attribute *attr,
1765                                          char *buf)
1766 {
1767         struct hd_struct *p = dev_to_part(dev);
1768         struct request_queue *q;
1769         struct block_device *bdev;
1770         ssize_t ret = -ENXIO;
1771
1772         bdev = bdget(part_devt(p));
1773         if (bdev == NULL)
1774                 goto out;
1775
1776         q = blk_trace_get_queue(bdev);
1777         if (q == NULL)
1778                 goto out_bdput;
1779
1780         mutex_lock(&q->blk_trace_mutex);
1781
1782         if (attr == &dev_attr_enable) {
1783                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1784                 goto out_unlock_bdev;
1785         }
1786
1787         if (q->blk_trace == NULL)
1788                 ret = sprintf(buf, "disabled\n");
1789         else if (attr == &dev_attr_act_mask)
1790                 ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
1791         else if (attr == &dev_attr_pid)
1792                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1793         else if (attr == &dev_attr_start_lba)
1794                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1795         else if (attr == &dev_attr_end_lba)
1796                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1797
1798 out_unlock_bdev:
1799         mutex_unlock(&q->blk_trace_mutex);
1800 out_bdput:
1801         bdput(bdev);
1802 out:
1803         return ret;
1804 }
1805
1806 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1807                                           struct device_attribute *attr,
1808                                           const char *buf, size_t count)
1809 {
1810         struct block_device *bdev;
1811         struct request_queue *q;
1812         struct hd_struct *p;
1813         u64 value;
1814         ssize_t ret = -EINVAL;
1815
1816         if (count == 0)
1817                 goto out;
1818
1819         if (attr == &dev_attr_act_mask) {
1820                 if (kstrtoull(buf, 0, &value)) {
1821                         /* Assume it is a list of trace category names */
1822                         ret = blk_trace_str2mask(buf);
1823                         if (ret < 0)
1824                                 goto out;
1825                         value = ret;
1826                 }
1827         } else if (kstrtoull(buf, 0, &value))
1828                 goto out;
1829
1830         ret = -ENXIO;
1831
1832         p = dev_to_part(dev);
1833         bdev = bdget(part_devt(p));
1834         if (bdev == NULL)
1835                 goto out;
1836
1837         q = blk_trace_get_queue(bdev);
1838         if (q == NULL)
1839                 goto out_bdput;
1840
1841         mutex_lock(&q->blk_trace_mutex);
1842
1843         if (attr == &dev_attr_enable) {
1844                 if (value)
1845                         ret = blk_trace_setup_queue(q, bdev);
1846                 else
1847                         ret = blk_trace_remove_queue(q);
1848                 goto out_unlock_bdev;
1849         }
1850
1851         ret = 0;
1852         if (q->blk_trace == NULL)
1853                 ret = blk_trace_setup_queue(q, bdev);
1854
1855         if (ret == 0) {
1856                 if (attr == &dev_attr_act_mask)
1857                         q->blk_trace->act_mask = value;
1858                 else if (attr == &dev_attr_pid)
1859                         q->blk_trace->pid = value;
1860                 else if (attr == &dev_attr_start_lba)
1861                         q->blk_trace->start_lba = value;
1862                 else if (attr == &dev_attr_end_lba)
1863                         q->blk_trace->end_lba = value;
1864         }
1865
1866 out_unlock_bdev:
1867         mutex_unlock(&q->blk_trace_mutex);
1868 out_bdput:
1869         bdput(bdev);
1870 out:
1871         return ret ? ret : count;
1872 }
1873
1874 int blk_trace_init_sysfs(struct device *dev)
1875 {
1876         return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1877 }
1878
1879 void blk_trace_remove_sysfs(struct device *dev)
1880 {
1881         sysfs_remove_group(&dev->kobj, &blk_trace_attr_group);
1882 }
1883
1884 #endif /* CONFIG_BLK_DEV_IO_TRACE */
1885
1886 #ifdef CONFIG_EVENT_TRACING
1887
1888 void blk_fill_rwbs(char *rwbs, unsigned int op, int bytes)
1889 {
1890         int i = 0;
1891
1892         if (op & REQ_PREFLUSH)
1893                 rwbs[i++] = 'F';
1894
1895         switch (op & REQ_OP_MASK) {
1896         case REQ_OP_WRITE:
1897         case REQ_OP_WRITE_SAME:
1898                 rwbs[i++] = 'W';
1899                 break;
1900         case REQ_OP_DISCARD:
1901                 rwbs[i++] = 'D';
1902                 break;
1903         case REQ_OP_SECURE_ERASE:
1904                 rwbs[i++] = 'D';
1905                 rwbs[i++] = 'E';
1906                 break;
1907         case REQ_OP_FLUSH:
1908                 rwbs[i++] = 'F';
1909                 break;
1910         case REQ_OP_READ:
1911                 rwbs[i++] = 'R';
1912                 break;
1913         default:
1914                 rwbs[i++] = 'N';
1915         }
1916
1917         if (op & REQ_FUA)
1918                 rwbs[i++] = 'F';
1919         if (op & REQ_RAHEAD)
1920                 rwbs[i++] = 'A';
1921         if (op & REQ_SYNC)
1922                 rwbs[i++] = 'S';
1923         if (op & REQ_META)
1924                 rwbs[i++] = 'M';
1925
1926         rwbs[i] = '\0';
1927 }
1928 EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1929
1930 #endif /* CONFIG_EVENT_TRACING */
1931