SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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/debugfs.h>
  25 #include <linux/time.h>
  26 #include <trace/block.h>
  27 #include <linux/uaccess.h>
  28 #include "trace_output.h"
  29
  30 static unsigned int blktrace_seq __read_mostly = 1;
  31
  32 static struct trace_array *blk_tr;
  33 static bool blk_tracer_enabled __read_mostly;
  34
  35 /* Select an alternative, minimalistic output than the original one */
  36 #define TRACE_BLK_OPT_CLASSIC   0x1
  37
  38 static struct tracer_opt blk_tracer_opts[] = {
  39         /* Default disable the minimalistic output */
  40         { TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
  41         { }
  42 };
  43
  44 static struct tracer_flags blk_tracer_flags = {
  45         .val  = 0,
  46         .opts = blk_tracer_opts,
  47 };
  48
  49 /* Global reference count of probes */
  50 static atomic_t blk_probes_ref = ATOMIC_INIT(0);
  51
  52 static void blk_register_tracepoints(void);
  53 static void blk_unregister_tracepoints(void);
  54
  55 /*
  56  * Send out a notify message.
  57  */
  58 static void trace_note(struct blk_trace *bt, pid_t pid, int action,
  59                        const void *data, size_t len)
  60 {
  61         struct blk_io_trace *t;
  62
  63         if (!bt->rchan)
  64                 return;
  65
  66         t = relay_reserve(bt->rchan, sizeof(*t) + len);
  67         if (t) {
  68                 const int cpu = smp_processor_id();
  69
  70                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
  71                 t->time = ktime_to_ns(ktime_get());
  72                 t->device = bt->dev;
  73                 t->action = action;
  74                 t->pid = pid;
  75                 t->cpu = cpu;
  76                 t->pdu_len = len;
  77                 memcpy((void *) t + sizeof(*t), data, len);
  78         }
  79 }
  80
  81 /*
  82  * Send out a notify for this process, if we haven't done so since a trace
  83  * started
  84  */
  85 static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
  86 {
  87         tsk->btrace_seq = blktrace_seq;
  88         trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));
  89 }
  90
  91 static void trace_note_time(struct blk_trace *bt)
  92 {
  93         struct timespec now;
  94         unsigned long flags;
  95         u32 words[2];
  96
  97         getnstimeofday(&now);
  98         words[0] = now.tv_sec;
  99         words[1] = now.tv_nsec;
 100
 101         local_irq_save(flags);
 102         trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
 103         local_irq_restore(flags);
 104 }
 105
 106 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 107 {
 108         int n;
 109         va_list args;
 110         unsigned long flags;
 111         char *buf;
 112
 113         if (blk_tr) {
 114                 va_start(args, fmt);
 115                 ftrace_vprintk(fmt, args);
 116                 va_end(args);
 117                 return;
 118         }
 119
 120         if (!bt->msg_data)
 121                 return;
 122
 123         local_irq_save(flags);
 124         buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
 125         va_start(args, fmt);
 126         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 127         va_end(args);
 128
 129         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
 130         local_irq_restore(flags);
 131 }
 132 EXPORT_SYMBOL_GPL(__trace_note_message);
 133
 134 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
 135                          pid_t pid)
 136 {
 137         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
 138                 return 1;
 139         if (sector < bt->start_lba || sector > bt->end_lba)
 140                 return 1;
 141         if (bt->pid && pid != bt->pid)
 142                 return 1;
 143
 144         return 0;
 145 }
 146
 147 /*
 148  * Data direction bit lookup
 149  */
 150 static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ),
 151                                          BLK_TC_ACT(BLK_TC_WRITE) };
 152
 153 /* The ilog2() calls fall out because they're constant */
 154 #define MASK_TC_BIT(rw, __name) ((rw & (1 << BIO_RW_ ## __name)) << \
 155           (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - BIO_RW_ ## __name))
 156
 157 /*
 158  * The worker for the various blk_add_trace*() types. Fills out a
 159  * blk_io_trace structure and places it in a per-cpu subbuffer.
 160  */
 161 static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 162                      int rw, u32 what, int error, int pdu_len, void *pdu_data)
 163 {
 164         struct task_struct *tsk = current;
 165         struct ring_buffer_event *event = NULL;
 166         struct blk_io_trace *t;
 167         unsigned long flags = 0;
 168         unsigned long *sequence;
 169         pid_t pid;
 170         int cpu, pc = 0;
 171
 172         if (unlikely(bt->trace_state != Blktrace_running ||
 173                      !blk_tracer_enabled))
 174                 return;
 175
 176         what |= ddir_act[rw & WRITE];
 177         what |= MASK_TC_BIT(rw, BARRIER);
 178         what |= MASK_TC_BIT(rw, SYNCIO);
 179         what |= MASK_TC_BIT(rw, AHEAD);
 180         what |= MASK_TC_BIT(rw, META);
 181         what |= MASK_TC_BIT(rw, DISCARD);
 182
 183         pid = tsk->pid;
 184         if (unlikely(act_log_check(bt, what, sector, pid)))
 185                 return;
 186         cpu = raw_smp_processor_id();
 187
 188         if (blk_tr) {
 189                 tracing_record_cmdline(current);
 190
 191                 pc = preempt_count();
 192                 event = trace_buffer_lock_reserve(blk_tr, TRACE_BLK,
 193                                                   sizeof(*t) + pdu_len,
 194                                                   0, pc);
 195                 if (!event)
 196                         return;
 197                 t = ring_buffer_event_data(event);
 198                 goto record_it;
 199         }
 200
 201         /*
 202          * A word about the locking here - we disable interrupts to reserve
 203          * some space in the relay per-cpu buffer, to prevent an irq
 204          * from coming in and stepping on our toes.
 205          */
 206         local_irq_save(flags);
 207
 208         if (unlikely(tsk->btrace_seq != blktrace_seq))
 209                 trace_note_tsk(bt, tsk);
 210
 211         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
 212         if (t) {
 213                 sequence = per_cpu_ptr(bt->sequence, cpu);
 214
 215                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 216                 t->sequence = ++(*sequence);
 217                 t->time = ktime_to_ns(ktime_get());
 218 record_it:
 219                 /*
 220                  * These two are not needed in ftrace as they are in the
 221                  * generic trace_entry, filled by tracing_generic_entry_update,
 222                  * but for the trace_event->bin() synthesizer benefit we do it
 223                  * here too.
 224                  */
 225                 t->cpu = cpu;
 226                 t->pid = pid;
 227
 228                 t->sector = sector;
 229                 t->bytes = bytes;
 230                 t->action = what;
 231                 t->device = bt->dev;
 232                 t->error = error;
 233                 t->pdu_len = pdu_len;
 234
 235                 if (pdu_len)
 236                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
 237
 238                 if (blk_tr) {
 239                         trace_buffer_unlock_commit(blk_tr, event, 0, pc);
 240                         return;
 241                 }
 242         }
 243
 244         local_irq_restore(flags);
 245 }
 246
 247 static struct dentry *blk_tree_root;
 248 static DEFINE_MUTEX(blk_tree_mutex);
 249
 250 static void blk_trace_cleanup(struct blk_trace *bt)
 251 {
 252         debugfs_remove(bt->msg_file);
 253         debugfs_remove(bt->dropped_file);
 254         relay_close(bt->rchan);
 255         free_percpu(bt->sequence);
 256         free_percpu(bt->msg_data);
 257         kfree(bt);
 258         if (atomic_dec_and_test(&blk_probes_ref))
 259                 blk_unregister_tracepoints();
 260 }
 261
 262 int blk_trace_remove(struct request_queue *q)
 263 {
 264         struct blk_trace *bt;
 265
 266         bt = xchg(&q->blk_trace, NULL);
 267         if (!bt)
 268                 return -EINVAL;
 269
 270         if (bt->trace_state == Blktrace_setup ||
 271             bt->trace_state == Blktrace_stopped)
 272                 blk_trace_cleanup(bt);
 273
 274         return 0;
 275 }
 276 EXPORT_SYMBOL_GPL(blk_trace_remove);
 277
 278 static int blk_dropped_open(struct inode *inode, struct file *filp)
 279 {
 280         filp->private_data = inode->i_private;
 281
 282         return 0;
 283 }
 284
 285 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
 286                                 size_t count, loff_t *ppos)
 287 {
 288         struct blk_trace *bt = filp->private_data;
 289         char buf[16];
 290
 291         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
 292
 293         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 294 }
 295
 296 static const struct file_operations blk_dropped_fops = {
 297         .owner =        THIS_MODULE,
 298         .open =         blk_dropped_open,
 299         .read =         blk_dropped_read,
 300 };
 301
 302 static int blk_msg_open(struct inode *inode, struct file *filp)
 303 {
 304         filp->private_data = inode->i_private;
 305
 306         return 0;
 307 }
 308
 309 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 310                                 size_t count, loff_t *ppos)
 311 {
 312         char *msg;
 313         struct blk_trace *bt;
 314
 315         if (count > BLK_TN_MAX_MSG)
 316                 return -EINVAL;
 317
 318         msg = kmalloc(count, GFP_KERNEL);
 319         if (msg == NULL)
 320                 return -ENOMEM;
 321
 322         if (copy_from_user(msg, buffer, count)) {
 323                 kfree(msg);
 324                 return -EFAULT;
 325         }
 326
 327         bt = filp->private_data;
 328         __trace_note_message(bt, "%s", msg);
 329         kfree(msg);
 330
 331         return count;
 332 }
 333
 334 static const struct file_operations blk_msg_fops = {
 335         .owner =        THIS_MODULE,
 336         .open =         blk_msg_open,
 337         .write =        blk_msg_write,
 338 };
 339
 340 /*
 341  * Keep track of how many times we encountered a full subbuffer, to aid
 342  * the user space app in telling how many lost events there were.
 343  */
 344 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
 345                                      void *prev_subbuf, size_t prev_padding)
 346 {
 347         struct blk_trace *bt;
 348
 349         if (!relay_buf_full(buf))
 350                 return 1;
 351
 352         bt = buf->chan->private_data;
 353         atomic_inc(&bt->dropped);
 354         return 0;
 355 }
 356
 357 static int blk_remove_buf_file_callback(struct dentry *dentry)
 358 {
 359         struct dentry *parent = dentry->d_parent;
 360         debugfs_remove(dentry);
 361
 362         /*
 363         * this will fail for all but the last file, but that is ok. what we
 364         * care about is the top level buts->name directory going away, when
 365         * the last trace file is gone. Then we don't have to rmdir() that
 366         * manually on trace stop, so it nicely solves the issue with
 367         * force killing of running traces.
 368         */
 369
 370         debugfs_remove(parent);
 371         return 0;
 372 }
 373
 374 static struct dentry *blk_create_buf_file_callback(const char *filename,
 375                                                    struct dentry *parent,
 376                                                    int mode,
 377                                                    struct rchan_buf *buf,
 378                                                    int *is_global)
 379 {
 380         return debugfs_create_file(filename, mode, parent, buf,
 381                                         &relay_file_operations);
 382 }
 383
 384 static struct rchan_callbacks blk_relay_callbacks = {
 385         .subbuf_start           = blk_subbuf_start_callback,
 386         .create_buf_file        = blk_create_buf_file_callback,
 387         .remove_buf_file        = blk_remove_buf_file_callback,
 388 };
 389
 390 /*
 391  * Setup everything required to start tracing
 392  */
 393 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 394                         struct blk_user_trace_setup *buts)
 395 {
 396         struct blk_trace *old_bt, *bt = NULL;
 397         struct dentry *dir = NULL;
 398         int ret, i;
 399
 400         if (!buts->buf_size || !buts->buf_nr)
 401                 return -EINVAL;
 402
 403         strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 404         buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 405
 406         /*
 407          * some device names have larger paths - convert the slashes
 408          * to underscores for this to work as expected
 409          */
 410         for (i = 0; i < strlen(buts->name); i++)
 411                 if (buts->name[i] == '/')
 412                         buts->name[i] = '_';
 413
 414         ret = -ENOMEM;
 415         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 416         if (!bt)
 417                 goto err;
 418
 419         bt->sequence = alloc_percpu(unsigned long);
 420         if (!bt->sequence)
 421                 goto err;
 422
 423         bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 424         if (!bt->msg_data)
 425                 goto err;
 426
 427         ret = -ENOENT;
 428
 429         if (!blk_tree_root) {
 430                 blk_tree_root = debugfs_create_dir("block", NULL);
 431                 if (!blk_tree_root)
 432                         goto err;
 433         }
 434
 435         dir = debugfs_create_dir(buts->name, blk_tree_root);
 436
 437         if (!dir)
 438                 goto err;
 439
 440         bt->dir = dir;
 441         bt->dev = dev;
 442         atomic_set(&bt->dropped, 0);
 443
 444         ret = -EIO;
 445         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
 446                                                &blk_dropped_fops);
 447         if (!bt->dropped_file)
 448                 goto err;
 449
 450         bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
 451         if (!bt->msg_file)
 452                 goto err;
 453
 454         bt->rchan = relay_open("trace", dir, buts->buf_size,
 455                                 buts->buf_nr, &blk_relay_callbacks, bt);
 456         if (!bt->rchan)
 457                 goto err;
 458
 459         bt->act_mask = buts->act_mask;
 460         if (!bt->act_mask)
 461                 bt->act_mask = (u16) -1;
 462
 463         bt->start_lba = buts->start_lba;
 464         bt->end_lba = buts->end_lba;
 465         if (!bt->end_lba)
 466                 bt->end_lba = -1ULL;
 467
 468         bt->pid = buts->pid;
 469         bt->trace_state = Blktrace_setup;
 470
 471         ret = -EBUSY;
 472         old_bt = xchg(&q->blk_trace, bt);
 473         if (old_bt) {
 474                 (void) xchg(&q->blk_trace, old_bt);
 475                 goto err;
 476         }
 477
 478         if (atomic_add_return(1, &blk_probes_ref) == 1)
 479                 blk_register_tracepoints();
 480
 481         return 0;
 482 err:
 483         if (bt) {
 484                 if (bt->msg_file)
 485                         debugfs_remove(bt->msg_file);
 486                 if (bt->dropped_file)
 487                         debugfs_remove(bt->dropped_file);
 488                 free_percpu(bt->sequence);
 489                 free_percpu(bt->msg_data);
 490                 if (bt->rchan)
 491                         relay_close(bt->rchan);
 492                 kfree(bt);
 493         }
 494         return ret;
 495 }
 496
 497 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 498                     char __user *arg)
 499 {
 500         struct blk_user_trace_setup buts;
 501         int ret;
 502
 503         ret = copy_from_user(&buts, arg, sizeof(buts));
 504         if (ret)
 505                 return -EFAULT;
 506
 507         ret = do_blk_trace_setup(q, name, dev, &buts);
 508         if (ret)
 509                 return ret;
 510
 511         if (copy_to_user(arg, &buts, sizeof(buts)))
 512                 return -EFAULT;
 513
 514         return 0;
 515 }
 516 EXPORT_SYMBOL_GPL(blk_trace_setup);
 517
 518 int blk_trace_startstop(struct request_queue *q, int start)
 519 {
 520         int ret;
 521         struct blk_trace *bt = q->blk_trace;
 522
 523         if (bt == NULL)
 524                 return -EINVAL;
 525
 526         /*
 527          * For starting a trace, we can transition from a setup or stopped
 528          * trace. For stopping a trace, the state must be running
 529          */
 530         ret = -EINVAL;
 531         if (start) {
 532                 if (bt->trace_state == Blktrace_setup ||
 533                     bt->trace_state == Blktrace_stopped) {
 534                         blktrace_seq++;
 535                         smp_mb();
 536                         bt->trace_state = Blktrace_running;
 537
 538                         trace_note_time(bt);
 539                         ret = 0;
 540                 }
 541         } else {
 542                 if (bt->trace_state == Blktrace_running) {
 543                         bt->trace_state = Blktrace_stopped;
 544                         relay_flush(bt->rchan);
 545                         ret = 0;
 546                 }
 547         }
 548
 549         return ret;
 550 }
 551 EXPORT_SYMBOL_GPL(blk_trace_startstop);
 552
 553 /**
 554  * blk_trace_ioctl: - handle the ioctls associated with tracing
 555  * @bdev:       the block device
 556  * @cmd:        the ioctl cmd
 557  * @arg:        the argument data, if any
 558  *
 559  **/
 560 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 561 {
 562         struct request_queue *q;
 563         int ret, start = 0;
 564         char b[BDEVNAME_SIZE];
 565
 566         q = bdev_get_queue(bdev);
 567         if (!q)
 568                 return -ENXIO;
 569
 570         mutex_lock(&bdev->bd_mutex);
 571
 572         switch (cmd) {
 573         case BLKTRACESETUP:
 574                 bdevname(bdev, b);
 575                 ret = blk_trace_setup(q, b, bdev->bd_dev, arg);
 576                 break;
 577         case BLKTRACESTART:
 578                 start = 1;
 579         case BLKTRACESTOP:
 580                 ret = blk_trace_startstop(q, start);
 581                 break;
 582         case BLKTRACETEARDOWN:
 583                 ret = blk_trace_remove(q);
 584                 break;
 585         default:
 586                 ret = -ENOTTY;
 587                 break;
 588         }
 589
 590         mutex_unlock(&bdev->bd_mutex);
 591         return ret;
 592 }
 593
 594 /**
 595  * blk_trace_shutdown: - stop and cleanup trace structures
 596  * @q:    the request queue associated with the device
 597  *
 598  **/
 599 void blk_trace_shutdown(struct request_queue *q)
 600 {
 601         if (q->blk_trace) {
 602                 blk_trace_startstop(q, 0);
 603                 blk_trace_remove(q);
 604         }
 605 }
 606
 607 /*
 608  * blktrace probes
 609  */
 610
 611 /**
 612  * blk_add_trace_rq - Add a trace for a request oriented action
 613  * @q:          queue the io is for
 614  * @rq:         the source request
 615  * @what:       the action
 616  *
 617  * Description:
 618  *     Records an action against a request. Will log the bio offset + size.
 619  *
 620  **/
 621 static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 622                                     u32 what)
 623 {
 624         struct blk_trace *bt = q->blk_trace;
 625         int rw = rq->cmd_flags & 0x03;
 626
 627         if (likely(!bt))
 628                 return;
 629
 630         if (blk_discard_rq(rq))
 631                 rw |= (1 << BIO_RW_DISCARD);
 632
 633         if (blk_pc_request(rq)) {
 634                 what |= BLK_TC_ACT(BLK_TC_PC);
 635                 __blk_add_trace(bt, 0, rq->data_len, rw, what, rq->errors,
 636                                 sizeof(rq->cmd), rq->cmd);
 637         } else  {
 638                 what |= BLK_TC_ACT(BLK_TC_FS);
 639                 __blk_add_trace(bt, rq->hard_sector, rq->hard_nr_sectors << 9,
 640                                 rw, what, rq->errors, 0, NULL);
 641         }
 642 }
 643
 644 static void blk_add_trace_rq_abort(struct request_queue *q, struct request *rq)
 645 {
 646         blk_add_trace_rq(q, rq, BLK_TA_ABORT);
 647 }
 648
 649 static void blk_add_trace_rq_insert(struct request_queue *q, struct request *rq)
 650 {
 651         blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 652 }
 653
 654 static void blk_add_trace_rq_issue(struct request_queue *q, struct request *rq)
 655 {
 656         blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
 657 }
 658
 659 static void blk_add_trace_rq_requeue(struct request_queue *q,
 660                                      struct request *rq)
 661 {
 662         blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
 663 }
 664
 665 static void blk_add_trace_rq_complete(struct request_queue *q,
 666                                       struct request *rq)
 667 {
 668         blk_add_trace_rq(q, rq, BLK_TA_COMPLETE);
 669 }
 670
 671 /**
 672  * blk_add_trace_bio - Add a trace for a bio oriented action
 673  * @q:          queue the io is for
 674  * @bio:        the source bio
 675  * @what:       the action
 676  *
 677  * Description:
 678  *     Records an action against a bio. Will log the bio offset + size.
 679  *
 680  **/
 681 static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
 682                                      u32 what)
 683 {
 684         struct blk_trace *bt = q->blk_trace;
 685
 686         if (likely(!bt))
 687                 return;
 688
 689         __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw, what,
 690                         !bio_flagged(bio, BIO_UPTODATE), 0, NULL);
 691 }
 692
 693 static void blk_add_trace_bio_bounce(struct request_queue *q, struct bio *bio)
 694 {
 695         blk_add_trace_bio(q, bio, BLK_TA_BOUNCE);
 696 }
 697
 698 static void blk_add_trace_bio_complete(struct request_queue *q, struct bio *bio)
 699 {
 700         blk_add_trace_bio(q, bio, BLK_TA_COMPLETE);
 701 }
 702
 703 static void blk_add_trace_bio_backmerge(struct request_queue *q,
 704                                         struct bio *bio)
 705 {
 706         blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
 707 }
 708
 709 static void blk_add_trace_bio_frontmerge(struct request_queue *q,
 710                                          struct bio *bio)
 711 {
 712         blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
 713 }
 714
 715 static void blk_add_trace_bio_queue(struct request_queue *q, struct bio *bio)
 716 {
 717         blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
 718 }
 719
 720 static void blk_add_trace_getrq(struct request_queue *q,
 721                                 struct bio *bio, int rw)
 722 {
 723         if (bio)
 724                 blk_add_trace_bio(q, bio, BLK_TA_GETRQ);
 725         else {
 726                 struct blk_trace *bt = q->blk_trace;
 727
 728                 if (bt)
 729                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_GETRQ, 0, 0, NULL);
 730         }
 731 }
 732
 733
 734 static void blk_add_trace_sleeprq(struct request_queue *q,
 735                                   struct bio *bio, int rw)
 736 {
 737         if (bio)
 738                 blk_add_trace_bio(q, bio, BLK_TA_SLEEPRQ);
 739         else {
 740                 struct blk_trace *bt = q->blk_trace;
 741
 742                 if (bt)
 743                         __blk_add_trace(bt, 0, 0, rw, BLK_TA_SLEEPRQ,
 744                                         0, 0, NULL);
 745         }
 746 }
 747
 748 static void blk_add_trace_plug(struct request_queue *q)
 749 {
 750         struct blk_trace *bt = q->blk_trace;
 751
 752         if (bt)
 753                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
 754 }
 755
 756 static void blk_add_trace_unplug_io(struct request_queue *q)
 757 {
 758         struct blk_trace *bt = q->blk_trace;
 759
 760         if (bt) {
 761                 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
 762                 __be64 rpdu = cpu_to_be64(pdu);
 763
 764                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_IO, 0,
 765                                 sizeof(rpdu), &rpdu);
 766         }
 767 }
 768
 769 static void blk_add_trace_unplug_timer(struct request_queue *q)
 770 {
 771         struct blk_trace *bt = q->blk_trace;
 772
 773         if (bt) {
 774                 unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
 775                 __be64 rpdu = cpu_to_be64(pdu);
 776
 777                 __blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_TIMER, 0,
 778                                 sizeof(rpdu), &rpdu);
 779         }
 780 }
 781
 782 static void blk_add_trace_split(struct request_queue *q, struct bio *bio,
 783                                 unsigned int pdu)
 784 {
 785         struct blk_trace *bt = q->blk_trace;
 786
 787         if (bt) {
 788                 __be64 rpdu = cpu_to_be64(pdu);
 789
 790                 __blk_add_trace(bt, bio->bi_sector, bio->bi_size, bio->bi_rw,
 791                                 BLK_TA_SPLIT, !bio_flagged(bio, BIO_UPTODATE),
 792                                 sizeof(rpdu), &rpdu);
 793         }
 794 }
 795
 796 /**
 797  * blk_add_trace_remap - Add a trace for a remap operation
 798  * @q:          queue the io is for
 799  * @bio:        the source bio
 800  * @dev:        target device
 801  * @from:       source sector
 802  * @to:         target sector
 803  *
 804  * Description:
 805  *     Device mapper or raid target sometimes need to split a bio because
 806  *     it spans a stripe (or similar). Add a trace for that action.
 807  *
 808  **/
 809 static void blk_add_trace_remap(struct request_queue *q, struct bio *bio,
 810                                        dev_t dev, sector_t from, sector_t to)
 811 {
 812         struct blk_trace *bt = q->blk_trace;
 813         struct blk_io_trace_remap r;
 814
 815         if (likely(!bt))
 816                 return;
 817
 818         r.device = cpu_to_be32(dev);
 819         r.device_from = cpu_to_be32(bio->bi_bdev->bd_dev);
 820         r.sector = cpu_to_be64(to);
 821
 822         __blk_add_trace(bt, from, bio->bi_size, bio->bi_rw, BLK_TA_REMAP,
 823                         !bio_flagged(bio, BIO_UPTODATE), sizeof(r), &r);
 824 }
 825
 826 /**
 827  * blk_add_driver_data - Add binary message with driver-specific data
 828  * @q:          queue the io is for
 829  * @rq:         io request
 830  * @data:       driver-specific data
 831  * @len:        length of driver-specific data
 832  *
 833  * Description:
 834  *     Some drivers might want to write driver-specific data per request.
 835  *
 836  **/
 837 void blk_add_driver_data(struct request_queue *q,
 838                          struct request *rq,
 839                          void *data, size_t len)
 840 {
 841         struct blk_trace *bt = q->blk_trace;
 842
 843         if (likely(!bt))
 844                 return;
 845
 846         if (blk_pc_request(rq))
 847                 __blk_add_trace(bt, 0, rq->data_len, 0, BLK_TA_DRV_DATA,
 848                                 rq->errors, len, data);
 849         else
 850                 __blk_add_trace(bt, rq->hard_sector, rq->hard_nr_sectors << 9,
 851                                 0, BLK_TA_DRV_DATA, rq->errors, len, data);
 852 }
 853 EXPORT_SYMBOL_GPL(blk_add_driver_data);
 854
 855 static void blk_register_tracepoints(void)
 856 {
 857         int ret;
 858
 859         ret = register_trace_block_rq_abort(blk_add_trace_rq_abort);
 860         WARN_ON(ret);
 861         ret = register_trace_block_rq_insert(blk_add_trace_rq_insert);
 862         WARN_ON(ret);
 863         ret = register_trace_block_rq_issue(blk_add_trace_rq_issue);
 864         WARN_ON(ret);
 865         ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue);
 866         WARN_ON(ret);
 867         ret = register_trace_block_rq_complete(blk_add_trace_rq_complete);
 868         WARN_ON(ret);
 869         ret = register_trace_block_bio_bounce(blk_add_trace_bio_bounce);
 870         WARN_ON(ret);
 871         ret = register_trace_block_bio_complete(blk_add_trace_bio_complete);
 872         WARN_ON(ret);
 873         ret = register_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
 874         WARN_ON(ret);
 875         ret = register_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
 876         WARN_ON(ret);
 877         ret = register_trace_block_bio_queue(blk_add_trace_bio_queue);
 878         WARN_ON(ret);
 879         ret = register_trace_block_getrq(blk_add_trace_getrq);
 880         WARN_ON(ret);
 881         ret = register_trace_block_sleeprq(blk_add_trace_sleeprq);
 882         WARN_ON(ret);
 883         ret = register_trace_block_plug(blk_add_trace_plug);
 884         WARN_ON(ret);
 885         ret = register_trace_block_unplug_timer(blk_add_trace_unplug_timer);
 886         WARN_ON(ret);
 887         ret = register_trace_block_unplug_io(blk_add_trace_unplug_io);
 888         WARN_ON(ret);
 889         ret = register_trace_block_split(blk_add_trace_split);
 890         WARN_ON(ret);
 891         ret = register_trace_block_remap(blk_add_trace_remap);
 892         WARN_ON(ret);
 893 }
 894
 895 static void blk_unregister_tracepoints(void)
 896 {
 897         unregister_trace_block_remap(blk_add_trace_remap);
 898         unregister_trace_block_split(blk_add_trace_split);
 899         unregister_trace_block_unplug_io(blk_add_trace_unplug_io);
 900         unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer);
 901         unregister_trace_block_plug(blk_add_trace_plug);
 902         unregister_trace_block_sleeprq(blk_add_trace_sleeprq);
 903         unregister_trace_block_getrq(blk_add_trace_getrq);
 904         unregister_trace_block_bio_queue(blk_add_trace_bio_queue);
 905         unregister_trace_block_bio_frontmerge(blk_add_trace_bio_frontmerge);
 906         unregister_trace_block_bio_backmerge(blk_add_trace_bio_backmerge);
 907         unregister_trace_block_bio_complete(blk_add_trace_bio_complete);
 908         unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce);
 909         unregister_trace_block_rq_complete(blk_add_trace_rq_complete);
 910         unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue);
 911         unregister_trace_block_rq_issue(blk_add_trace_rq_issue);
 912         unregister_trace_block_rq_insert(blk_add_trace_rq_insert);
 913         unregister_trace_block_rq_abort(blk_add_trace_rq_abort);
 914
 915         tracepoint_synchronize_unregister();
 916 }
 917
 918 /*
 919  * struct blk_io_tracer formatting routines
 920  */
 921
 922 static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
 923 {
 924         int i = 0;
 925
 926         if (t->action & BLK_TC_DISCARD)
 927                 rwbs[i++] = 'D';
 928         else if (t->action & BLK_TC_WRITE)
 929                 rwbs[i++] = 'W';
 930         else if (t->bytes)
 931                 rwbs[i++] = 'R';
 932         else
 933                 rwbs[i++] = 'N';
 934
 935         if (t->action & BLK_TC_AHEAD)
 936                 rwbs[i++] = 'A';
 937         if (t->action & BLK_TC_BARRIER)
 938                 rwbs[i++] = 'B';
 939         if (t->action & BLK_TC_SYNC)
 940                 rwbs[i++] = 'S';
 941         if (t->action & BLK_TC_META)
 942                 rwbs[i++] = 'M';
 943
 944         rwbs[i] = '\0';
 945 }
 946
 947 static inline
 948 const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
 949 {
 950         return (const struct blk_io_trace *)ent;
 951 }
 952
 953 static inline const void *pdu_start(const struct trace_entry *ent)
 954 {
 955         return te_blk_io_trace(ent) + 1;
 956 }
 957
 958 static inline u32 t_sec(const struct trace_entry *ent)
 959 {
 960         return te_blk_io_trace(ent)->bytes >> 9;
 961 }
 962
 963 static inline unsigned long long t_sector(const struct trace_entry *ent)
 964 {
 965         return te_blk_io_trace(ent)->sector;
 966 }
 967
 968 static inline __u16 t_error(const struct trace_entry *ent)
 969 {
 970         return te_blk_io_trace(ent)->sector;
 971 }
 972
 973 static __u64 get_pdu_int(const struct trace_entry *ent)
 974 {
 975         const __u64 *val = pdu_start(ent);
 976         return be64_to_cpu(*val);
 977 }
 978
 979 static void get_pdu_remap(const struct trace_entry *ent,
 980                           struct blk_io_trace_remap *r)
 981 {
 982         const struct blk_io_trace_remap *__r = pdu_start(ent);
 983         __u64 sector = __r->sector;
 984
 985         r->device = be32_to_cpu(__r->device);
 986         r->device_from = be32_to_cpu(__r->device_from);
 987         r->sector = be64_to_cpu(sector);
 988 }
 989
 990 static int blk_log_action_iter(struct trace_iterator *iter, const char *act)
 991 {
 992         char rwbs[6];
 993         unsigned long long ts  = ns2usecs(iter->ts);
 994         unsigned long usec_rem = do_div(ts, USEC_PER_SEC);
 995         unsigned secs          = (unsigned long)ts;
 996         const struct trace_entry *ent = iter->ent;
 997         const struct blk_io_trace *t = (const struct blk_io_trace *)ent;
 998
 999         fill_rwbs(rwbs, t);
1000
1001         return trace_seq_printf(&iter->seq,
1002                                 "%3d,%-3d %2d %5d.%06lu %5u %2s %3s ",
1003                                 MAJOR(t->device), MINOR(t->device), iter->cpu,
1004                                 secs, usec_rem, ent->pid, act, rwbs);
1005 }
1006
1007 static int blk_log_action_seq(struct trace_seq *s, const struct blk_io_trace *t,
1008                               const char *act)
1009 {
1010         char rwbs[6];
1011         fill_rwbs(rwbs, t);
1012         return trace_seq_printf(s, "%3d,%-3d %2s %3s ",
1013                                 MAJOR(t->device), MINOR(t->device), act, rwbs);
1014 }
1015
1016 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
1017 {
1018         char cmd[TASK_COMM_LEN];
1019
1020         trace_find_cmdline(ent->pid, cmd);
1021
1022         if (t_sec(ent))
1023                 return trace_seq_printf(s, "%llu + %u [%s]\n",
1024                                         t_sector(ent), t_sec(ent), cmd);
1025         return trace_seq_printf(s, "[%s]\n", cmd);
1026 }
1027
1028 static int blk_log_with_error(struct trace_seq *s,
1029                               const struct trace_entry *ent)
1030 {
1031         if (t_sec(ent))
1032                 return trace_seq_printf(s, "%llu + %u [%d]\n", t_sector(ent),
1033                                         t_sec(ent), t_error(ent));
1034         return trace_seq_printf(s, "%llu [%d]\n", t_sector(ent), t_error(ent));
1035 }
1036
1037 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
1038 {
1039         struct blk_io_trace_remap r = { .device = 0, };
1040
1041         get_pdu_remap(ent, &r);
1042         return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
1043                                t_sector(ent),
1044                                t_sec(ent), MAJOR(r.device), MINOR(r.device),
1045                                (unsigned long long)r.sector);
1046 }
1047
1048 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)
1049 {
1050         char cmd[TASK_COMM_LEN];
1051
1052         trace_find_cmdline(ent->pid, cmd);
1053
1054         return trace_seq_printf(s, "[%s]\n", cmd);
1055 }
1056
1057 static int blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent)
1058 {
1059         char cmd[TASK_COMM_LEN];
1060
1061         trace_find_cmdline(ent->pid, cmd);
1062
1063         return trace_seq_printf(s, "[%s] %llu\n", cmd, get_pdu_int(ent));
1064 }
1065
1066 static int blk_log_split(struct trace_seq *s, const struct trace_entry *ent)
1067 {
1068         char cmd[TASK_COMM_LEN];
1069
1070         trace_find_cmdline(ent->pid, cmd);
1071
1072         return trace_seq_printf(s, "%llu / %llu [%s]\n", t_sector(ent),
1073                                 get_pdu_int(ent), cmd);
1074 }
1075
1076 /*
1077  * struct tracer operations
1078  */
1079
1080 static void blk_tracer_print_header(struct seq_file *m)
1081 {
1082         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1083                 return;
1084         seq_puts(m, "# DEV   CPU TIMESTAMP     PID ACT FLG\n"
1085                     "#  |     |     |           |   |   |\n");
1086 }
1087
1088 static void blk_tracer_start(struct trace_array *tr)
1089 {
1090         if (atomic_add_return(1, &blk_probes_ref) == 1)
1091                 blk_register_tracepoints();
1092         trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1093 }
1094
1095 static int blk_tracer_init(struct trace_array *tr)
1096 {
1097         blk_tr = tr;
1098         blk_tracer_start(tr);
1099         blk_tracer_enabled = true;
1100         return 0;
1101 }
1102
1103 static void blk_tracer_stop(struct trace_array *tr)
1104 {
1105         trace_flags |= TRACE_ITER_CONTEXT_INFO;
1106         if (atomic_dec_and_test(&blk_probes_ref))
1107                 blk_unregister_tracepoints();
1108 }
1109
1110 static void blk_tracer_reset(struct trace_array *tr)
1111 {
1112         if (!atomic_read(&blk_probes_ref))
1113                 return;
1114
1115         blk_tracer_enabled = false;
1116         blk_tracer_stop(tr);
1117 }
1118
1119 static struct {
1120         const char *act[2];
1121         int        (*print)(struct trace_seq *s, const struct trace_entry *ent);
1122 } what2act[] __read_mostly = {
1123         [__BLK_TA_QUEUE]        = {{  "Q", "queue" },      blk_log_generic },
1124         [__BLK_TA_BACKMERGE]    = {{  "M", "backmerge" },  blk_log_generic },
1125         [__BLK_TA_FRONTMERGE]   = {{  "F", "frontmerge" }, blk_log_generic },
1126         [__BLK_TA_GETRQ]        = {{  "G", "getrq" },      blk_log_generic },
1127         [__BLK_TA_SLEEPRQ]      = {{  "S", "sleeprq" },    blk_log_generic },
1128         [__BLK_TA_REQUEUE]      = {{  "R", "requeue" },    blk_log_with_error },
1129         [__BLK_TA_ISSUE]        = {{  "D", "issue" },      blk_log_generic },
1130         [__BLK_TA_COMPLETE]     = {{  "C", "complete" },   blk_log_with_error },
1131         [__BLK_TA_PLUG]         = {{  "P", "plug" },       blk_log_plug },
1132         [__BLK_TA_UNPLUG_IO]    = {{  "U", "unplug_io" },  blk_log_unplug },
1133         [__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
1134         [__BLK_TA_INSERT]       = {{  "I", "insert" },     blk_log_generic },
1135         [__BLK_TA_SPLIT]        = {{  "X", "split" },      blk_log_split },
1136         [__BLK_TA_BOUNCE]       = {{  "B", "bounce" },     blk_log_generic },
1137         [__BLK_TA_REMAP]        = {{  "A", "remap" },      blk_log_remap },
1138 };
1139
1140 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1141                                                int flags)
1142 {
1143         struct trace_seq *s = &iter->seq;
1144         const struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1145         const u16 what = t->action & ((1 << BLK_TC_SHIFT) - 1);
1146         int ret;
1147
1148         if (!trace_print_context(iter))
1149                 return TRACE_TYPE_PARTIAL_LINE;
1150
1151         if (unlikely(what == 0 || what > ARRAY_SIZE(what2act)))
1152                 ret = trace_seq_printf(s, "Bad pc action %x\n", what);
1153         else {
1154                 const bool long_act = !!(trace_flags & TRACE_ITER_VERBOSE);
1155                 ret = blk_log_action_seq(s, t, what2act[what].act[long_act]);
1156                 if (ret)
1157                         ret = what2act[what].print(s, iter->ent);
1158         }
1159
1160         return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1161 }
1162
1163 static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1164 {
1165         struct trace_seq *s = &iter->seq;
1166         struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1167         const int offset = offsetof(struct blk_io_trace, sector);
1168         struct blk_io_trace old = {
1169                 .magic    = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1170                 .time     = ns2usecs(iter->ts),
1171         };
1172
1173         if (!trace_seq_putmem(s, &old, offset))
1174                 return 0;
1175         return trace_seq_putmem(s, &t->sector,
1176                                 sizeof(old) - offset + t->pdu_len);
1177 }
1178
1179 static enum print_line_t
1180 blk_trace_event_print_binary(struct trace_iterator *iter, int flags)
1181 {
1182         return blk_trace_synthesize_old_trace(iter) ?
1183                         TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1184 }
1185
1186 static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1187 {
1188         const struct blk_io_trace *t;
1189         u16 what;
1190         int ret;
1191
1192         if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1193                 return TRACE_TYPE_UNHANDLED;
1194
1195         t = (const struct blk_io_trace *)iter->ent;
1196         what = t->action & ((1 << BLK_TC_SHIFT) - 1);
1197
1198         if (unlikely(what == 0 || what > ARRAY_SIZE(what2act)))
1199                 ret = trace_seq_printf(&iter->seq, "Bad pc action %x\n", what);
1200         else {
1201                 const bool long_act = !!(trace_flags & TRACE_ITER_VERBOSE);
1202                 ret = blk_log_action_iter(iter, what2act[what].act[long_act]);
1203                 if (ret)
1204                         ret = what2act[what].print(&iter->seq, iter->ent);
1205         }
1206
1207         return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
1208 }
1209
1210 static struct tracer blk_tracer __read_mostly = {
1211         .name           = "blk",
1212         .init           = blk_tracer_init,
1213         .reset          = blk_tracer_reset,
1214         .start          = blk_tracer_start,
1215         .stop           = blk_tracer_stop,
1216         .print_header   = blk_tracer_print_header,
1217         .print_line     = blk_tracer_print_line,
1218         .flags          = &blk_tracer_flags,
1219 };
1220
1221 static struct trace_event trace_blk_event = {
1222         .type           = TRACE_BLK,
1223         .trace          = blk_trace_event_print,
1224         .binary         = blk_trace_event_print_binary,
1225 };
1226
1227 static int __init init_blk_tracer(void)
1228 {
1229         if (!register_ftrace_event(&trace_blk_event)) {
1230                 pr_warning("Warning: could not register block events\n");
1231                 return 1;
1232         }
1233
1234         if (register_tracer(&blk_tracer) != 0) {
1235                 pr_warning("Warning: could not register the block tracer\n");
1236                 unregister_ftrace_event(&trace_blk_event);
1237                 return 1;
1238         }
1239
1240         return 0;
1241 }
1242
1243 device_initcall(init_blk_tracer);
1244
1245 static int blk_trace_remove_queue(struct request_queue *q)
1246 {
1247         struct blk_trace *bt;
1248
1249         bt = xchg(&q->blk_trace, NULL);
1250         if (bt == NULL)
1251                 return -EINVAL;
1252
1253         kfree(bt);
1254         return 0;
1255 }
1256
1257 /*
1258  * Setup everything required to start tracing
1259  */
1260 static int blk_trace_setup_queue(struct request_queue *q, dev_t dev)
1261 {
1262         struct blk_trace *old_bt, *bt = NULL;
1263
1264         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
1265         if (!bt)
1266                 return -ENOMEM;
1267
1268         bt->dev = dev;
1269         bt->act_mask = (u16)-1;
1270         bt->end_lba = -1ULL;
1271         bt->trace_state = Blktrace_running;
1272
1273         old_bt = xchg(&q->blk_trace, bt);
1274         if (old_bt != NULL) {
1275                 (void)xchg(&q->blk_trace, old_bt);
1276                 kfree(bt);
1277                 return -EBUSY;
1278         }
1279
1280         return 0;
1281 }
1282
1283 /*
1284  * sysfs interface to enable and configure tracing
1285  */
1286
1287 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1288                                          struct device_attribute *attr,
1289                                          char *buf);
1290 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1291                                           struct device_attribute *attr,
1292                                           const char *buf, size_t count);
1293 #define BLK_TRACE_DEVICE_ATTR(_name) \
1294         DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1295                     sysfs_blk_trace_attr_show, \
1296                     sysfs_blk_trace_attr_store)
1297
1298 static BLK_TRACE_DEVICE_ATTR(enable);
1299 static BLK_TRACE_DEVICE_ATTR(act_mask);
1300 static BLK_TRACE_DEVICE_ATTR(pid);
1301 static BLK_TRACE_DEVICE_ATTR(start_lba);
1302 static BLK_TRACE_DEVICE_ATTR(end_lba);
1303
1304 static struct attribute *blk_trace_attrs[] = {
1305         &dev_attr_enable.attr,
1306         &dev_attr_act_mask.attr,
1307         &dev_attr_pid.attr,
1308         &dev_attr_start_lba.attr,
1309         &dev_attr_end_lba.attr,
1310         NULL
1311 };
1312
1313 struct attribute_group blk_trace_attr_group = {
1314         .name  = "trace",
1315         .attrs = blk_trace_attrs,
1316 };
1317
1318 static int blk_str2act_mask(const char *str)
1319 {
1320         int mask = 0;
1321         char *copy = kstrdup(str, GFP_KERNEL), *s;
1322
1323         if (copy == NULL)
1324                 return -ENOMEM;
1325
1326         s = strstrip(copy);
1327
1328         while (1) {
1329                 char *sep = strchr(s, ',');
1330
1331                 if (sep != NULL)
1332                         *sep = '\0';
1333
1334                 if (strcasecmp(s, "barrier") == 0)
1335                         mask |= BLK_TC_BARRIER;
1336                 else if (strcasecmp(s, "complete") == 0)
1337                         mask |= BLK_TC_COMPLETE;
1338                 else if (strcasecmp(s, "fs") == 0)
1339                         mask |= BLK_TC_FS;
1340                 else if (strcasecmp(s, "issue") == 0)
1341                         mask |= BLK_TC_ISSUE;
1342                 else if (strcasecmp(s, "pc") == 0)
1343                         mask |= BLK_TC_PC;
1344                 else if (strcasecmp(s, "queue") == 0)
1345                         mask |= BLK_TC_QUEUE;
1346                 else if (strcasecmp(s, "read") == 0)
1347                         mask |= BLK_TC_READ;
1348                 else if (strcasecmp(s, "requeue") == 0)
1349                         mask |= BLK_TC_REQUEUE;
1350                 else if (strcasecmp(s, "sync") == 0)
1351                         mask |= BLK_TC_SYNC;
1352                 else if (strcasecmp(s, "write") == 0)
1353                         mask |= BLK_TC_WRITE;
1354
1355                 if (sep == NULL)
1356                         break;
1357
1358                 s = sep + 1;
1359         }
1360         kfree(copy);
1361
1362         return mask;
1363 }
1364
1365 static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
1366 {
1367         if (bdev->bd_disk == NULL)
1368                 return NULL;
1369
1370         return bdev_get_queue(bdev);
1371 }
1372
1373 static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1374                                          struct device_attribute *attr,
1375                                          char *buf)
1376 {
1377         struct hd_struct *p = dev_to_part(dev);
1378         struct request_queue *q;
1379         struct block_device *bdev;
1380         ssize_t ret = -ENXIO;
1381
1382         lock_kernel();
1383         bdev = bdget(part_devt(p));
1384         if (bdev == NULL)
1385                 goto out_unlock_kernel;
1386
1387         q = blk_trace_get_queue(bdev);
1388         if (q == NULL)
1389                 goto out_bdput;
1390
1391         mutex_lock(&bdev->bd_mutex);
1392
1393         if (attr == &dev_attr_enable) {
1394                 ret = sprintf(buf, "%u\n", !!q->blk_trace);
1395                 goto out_unlock_bdev;
1396         }
1397
1398         if (q->blk_trace == NULL)
1399                 ret = sprintf(buf, "disabled\n");
1400         else if (attr == &dev_attr_act_mask)
1401                 ret = sprintf(buf, "%#x\n", q->blk_trace->act_mask);
1402         else if (attr == &dev_attr_pid)
1403                 ret = sprintf(buf, "%u\n", q->blk_trace->pid);
1404         else if (attr == &dev_attr_start_lba)
1405                 ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
1406         else if (attr == &dev_attr_end_lba)
1407                 ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
1408
1409 out_unlock_bdev:
1410         mutex_unlock(&bdev->bd_mutex);
1411 out_bdput:
1412         bdput(bdev);
1413 out_unlock_kernel:
1414         unlock_kernel();
1415         return ret;
1416 }
1417
1418 static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1419                                           struct device_attribute *attr,
1420                                           const char *buf, size_t count)
1421 {
1422         struct block_device *bdev;
1423         struct request_queue *q;
1424         struct hd_struct *p;
1425         u64 value;
1426         ssize_t ret = -ENXIO;
1427
1428         if (count == 0)
1429                 goto out;
1430
1431         if (attr == &dev_attr_act_mask) {
1432                 if (sscanf(buf, "%llx", &value) != 1) {
1433                         /* Assume it is a list of trace category names */
1434                         value = blk_str2act_mask(buf);
1435                         if (value < 0)
1436                                 goto out;
1437                 }
1438         } else if (sscanf(buf, "%llu", &value) != 1)
1439                 goto out;
1440
1441         lock_kernel();
1442         p = dev_to_part(dev);
1443         bdev = bdget(part_devt(p));
1444         if (bdev == NULL)
1445                 goto out_unlock_kernel;
1446
1447         q = blk_trace_get_queue(bdev);
1448         if (q == NULL)
1449                 goto out_bdput;
1450
1451         mutex_lock(&bdev->bd_mutex);
1452
1453         if (attr == &dev_attr_enable) {
1454                 if (value)
1455                         ret = blk_trace_setup_queue(q, bdev->bd_dev);
1456                 else
1457                         ret = blk_trace_remove_queue(q);
1458                 goto out_unlock_bdev;
1459         }
1460
1461         ret = 0;
1462         if (q->blk_trace == NULL)
1463                 ret = blk_trace_setup_queue(q, bdev->bd_dev);
1464
1465         if (ret == 0) {
1466                 if (attr == &dev_attr_act_mask)
1467                         q->blk_trace->act_mask = value;
1468                 else if (attr == &dev_attr_pid)
1469                         q->blk_trace->pid = value;
1470                 else if (attr == &dev_attr_start_lba)
1471                         q->blk_trace->start_lba = value;
1472                 else if (attr == &dev_attr_end_lba)
1473                         q->blk_trace->end_lba = value;
1474         }
1475
1476 out_unlock_bdev:
1477         mutex_unlock(&bdev->bd_mutex);
1478 out_bdput:
1479         bdput(bdev);
1480 out_unlock_kernel:
1481         unlock_kernel();
1482 out:
1483         return ret ? ret : count;
1484 }
1485