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
  40static unsigned int blktrace_seq __read_mostly = 1;
  41
  42static struct trace_array *blk_tr;
  43static bool blk_tracer_enabled __read_mostly;
  44
  45static LIST_HEAD(running_trace_list);
  46static __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
  53static 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
  63static struct tracer_flags blk_tracer_flags = {
  64	.val  = 0,
  65	.opts = blk_tracer_opts,
  66};
  67
  68/* Global reference count of probes */
  69static DEFINE_MUTEX(blk_probe_mutex);
  70static int blk_probes_ref;
  71
  72static void blk_register_tracepoints(void);
  73static void blk_unregister_tracepoints(void);
  74
  75/*
  76 * Send out a notify message.
  77 */
  78static 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());
 109record_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 */
 128static 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
 142static 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
 158void __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}
 193EXPORT_SYMBOL_GPL(__trace_note_message);
 194
 195static 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 */
 211static 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 */
 225static 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());
 291record_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
 322static 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
 333static 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
 341static 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
 349static void blk_trace_cleanup(struct blk_trace *bt)
 350{
 351	blk_trace_free(bt);
 352	put_probe_ref();
 353}
 354
 355static 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
 369int 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}
 379EXPORT_SYMBOL_GPL(blk_trace_remove);
 380
 381static 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
 392static 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
 399static 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
 419static 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 */
 430static 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
 443static int blk_remove_buf_file_callback(struct dentry *dentry)
 444{
 445	debugfs_remove(dentry);
 446
 447	return 0;
 448}
 449
 450static 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
 460static 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
 466static 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 */
 486static 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	strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
 498	buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
 499
 500	/*
 501	 * some device names have larger paths - convert the slashes
 502	 * to underscores for this to work as expected
 503	 */
 504	strreplace(buts->name, '/', '_');
 505
 506	bt = kzalloc(sizeof(*bt), GFP_KERNEL);
 507	if (!bt)
 508		return -ENOMEM;
 509
 510	ret = -ENOMEM;
 511	bt->sequence = alloc_percpu(unsigned long);
 512	if (!bt->sequence)
 513		goto err;
 514
 515	bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 516	if (!bt->msg_data)
 517		goto err;
 518
 519	ret = -ENOENT;
 520
 521	if (!blk_debugfs_root)
 522		goto err;
 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;
 571err:
 572	if (dir && !bt->dir)
 573		dput(dir);
 574	if (ret)
 575		blk_trace_free(bt);
 576	return ret;
 577}
 578
 579static 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
 600int 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}
 612EXPORT_SYMBOL_GPL(blk_trace_setup);
 613
 614#if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 615static 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
 648static 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
 688int 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}
 698EXPORT_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 **/
 713int 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 **/
 758void 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
 771static union kernfs_node_id *
 772blk_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
 784static union kernfs_node_id *
 785blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 786{
 787	return NULL;
 788}
 789#endif
 790
 791static union kernfs_node_id *
 792blk_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 **/
 816static 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
 834static 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
 841static 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
 848static 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
 856static 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 **/
 874static 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
 887static 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
 893static 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
 900static 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
 908static 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
 916static 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
 922static 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
 938static 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
 953static 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
 961static 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
 979static 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 **/
1008static 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 **/
1040static 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 **/
1071void 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}
1084EXPORT_SYMBOL_GPL(blk_add_driver_data);
1085
1086static 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
1124static 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
1150static 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';
1180out:
1181	rwbs[i] = '\0';
1182}
1183
1184static inline
1185const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1186{
1187	return (const struct blk_io_trace *)ent;
1188}
1189
1190static 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
1196static inline const void *cgid_start(const struct trace_entry *ent)
1197{
1198	return (void *)(te_blk_io_trace(ent) + 1);
1199}
1200
1201static 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
1207static inline u32 t_action(const struct trace_entry *ent)
1208{
1209	return te_blk_io_trace(ent)->action;
1210}
1211
1212static inline u32 t_bytes(const struct trace_entry *ent)
1213{
1214	return te_blk_io_trace(ent)->bytes;
1215}
1216
1217static inline u32 t_sec(const struct trace_entry *ent)
1218{
1219	return te_blk_io_trace(ent)->bytes >> 9;
1220}
1221
1222static inline unsigned long long t_sector(const struct trace_entry *ent)
1223{
1224	return te_blk_io_trace(ent)->sector;
1225}
1226
1227static inline __u16 t_error(const struct trace_entry *ent)
1228{
1229	return te_blk_io_trace(ent)->error;
1230}
1231
1232static __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
1238static 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
1249typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act,
1250	bool has_cg);
1251
1252static 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
1269static 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
1297static 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
1336static 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
1355static 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
1372static 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
1383static 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
1392static 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
1401static 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
1411static 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
1424static 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
1432static void blk_tracer_start(struct trace_array *tr)
1433{
1434	blk_tracer_enabled = true;
1435}
1436
1437static int blk_tracer_init(struct trace_array *tr)
1438{
1439	blk_tr = tr;
1440	blk_tracer_start(tr);
1441	return 0;
1442}
1443
1444static void blk_tracer_stop(struct trace_array *tr)
1445{
1446	blk_tracer_enabled = false;
1447}
1448
1449static void blk_tracer_reset(struct trace_array *tr)
1450{
1451	blk_tracer_stop(tr);
1452}
1453
1454static 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
1476static 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
1509static 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
1515static 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
1530static enum print_line_t
1531blk_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
1539static 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
1547static int
1548blk_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
1560static 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
1572static struct trace_event_functions trace_blk_event_funcs = {
1573	.trace		= blk_trace_event_print,
1574	.binary		= blk_trace_event_print_binary,
1575};
1576
1577static struct trace_event trace_blk_event = {
1578	.type		= TRACE_BLK,
1579	.funcs		= &trace_blk_event_funcs,
1580};
1581
1582static 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
1598device_initcall(init_blk_tracer);
1599
1600static 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 */
1616static 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
1642free_bt:
1643	blk_trace_free(bt);
1644	return ret;
1645}
1646
1647/*
1648 * sysfs interface to enable and configure tracing
1649 */
1650
1651static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1652					 struct device_attribute *attr,
1653					 char *buf);
1654static 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
1662static BLK_TRACE_DEVICE_ATTR(enable);
1663static BLK_TRACE_DEVICE_ATTR(act_mask);
1664static BLK_TRACE_DEVICE_ATTR(pid);
1665static BLK_TRACE_DEVICE_ATTR(start_lba);
1666static BLK_TRACE_DEVICE_ATTR(end_lba);
1667
1668static 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
1677struct attribute_group blk_trace_attr_group = {
1678	.name  = "trace",
1679	.attrs = blk_trace_attrs,
1680};
1681
1682static 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
1704static 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
1739static 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
1755static 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
1763static 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
1798out_unlock_bdev:
1799	mutex_unlock(&q->blk_trace_mutex);
1800out_bdput:
1801	bdput(bdev);
1802out:
1803	return ret;
1804}
1805
1806static 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
1866out_unlock_bdev:
1867	mutex_unlock(&q->blk_trace_mutex);
1868out_bdput:
1869	bdput(bdev);
1870out:
1871	return ret ? ret : count;
1872}
1873
1874int blk_trace_init_sysfs(struct device *dev)
1875{
1876	return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
1877}
1878
1879void 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
1888void 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}
1928EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1929
1930#endif /* CONFIG_EVENT_TRACING */
1931