1	// SPDX-License-Identifier: GPL-2.0
2	/*
3	* Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
4	*
5	*/
6
7	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9	#include <linux/kernel.h>
10	#include <linux/blkdev.h>
11	#include <linux/blktrace_api.h>
12	#include <linux/percpu.h>
13	#include <linux/init.h>
14	#include <linux/mutex.h>
15	#include <linux/slab.h>
16	#include <linux/debugfs.h>
17	#include <linux/export.h>
18	#include <linux/time.h>
19	#include <linux/uaccess.h>
20	#include <linux/list.h>
21	#include <linux/blk-cgroup.h>
22
23	#include "../../block/blk.h"
24
25	#include <trace/events/block.h>
26
27	#include "trace_output.h"
28
29	#ifdef CONFIG_BLK_DEV_IO_TRACE
30
31	static unsigned int blktrace_seq __read_mostly = 1;
32
33	static struct trace_array *blk_tr;
34	static bool blk_tracer_enabled __read_mostly;
35
36	static LIST_HEAD(running_trace_list);
37	static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(running_trace_lock);
38
39	/* Select an alternative, minimalistic output than the original one */
40	#define TRACE_BLK_OPT_CLASSIC 0x1
41	#define TRACE_BLK_OPT_CGROUP 0x2
42	#define TRACE_BLK_OPT_CGNAME 0x4
43
44	static struct tracer_opt blk_tracer_opts[] = {
45	/* Default disable the minimalistic output */
46	{ TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
47	#ifdef CONFIG_BLK_CGROUP
48	{ TRACER_OPT(blk_cgroup, TRACE_BLK_OPT_CGROUP) },
49	{ TRACER_OPT(blk_cgname, TRACE_BLK_OPT_CGNAME) },
50	#endif
51	{ }
52	};
53
54	static struct tracer_flags blk_tracer_flags = {
55	.val = 0,
56	.opts = blk_tracer_opts,
57	};
58
59	/* Global reference count of probes */
60	static DEFINE_MUTEX(blk_probe_mutex);
61	static int blk_probes_ref;
62
63	static void blk_register_tracepoints(void);
64	static void blk_unregister_tracepoints(void);
65
66	/*
67	* Send out a notify message.
68	*/
69	static void trace_note(struct blk_trace *bt, pid_t pid, int action,
70	const void *data, size_t len, u64 cgid)
71	{
72	struct blk_io_trace *t;
73	struct ring_buffer_event *event = NULL;
74	struct trace_buffer *buffer = NULL;
75	unsigned int trace_ctx = 0;
76	int cpu = smp_processor_id();
77	bool blk_tracer = blk_tracer_enabled;
78	ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
79
80	if (blk_tracer) {
81	buffer = blk_tr->array_buffer.buffer;
82	trace_ctx = tracing_gen_ctx_flags(irqflags: 0);
83	event = trace_buffer_lock_reserve(buffer, type: TRACE_BLK,
84	len: sizeof(*t) + len + cgid_len,
85	trace_ctx);
86	if (!event)
87	return;
88	t = ring_buffer_event_data(event);
89	goto record_it;
90	}
91
92	if (!bt->rchan)
93	return;
94
95	t = relay_reserve(chan: bt->rchan, length: sizeof(*t) + len + cgid_len);
96	if (t) {
97	t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
98	t->time = ktime_to_ns(kt: ktime_get());
99	record_it:
100	t->device = bt->dev;
101	t->action = action | (cgid ? __BLK_TN_CGROUP : 0);
102	t->pid = pid;
103	t->cpu = cpu;
104	t->pdu_len = len + cgid_len;
105	if (cgid_len)
106	memcpy((void *)t + sizeof(*t), &cgid, cgid_len);
107	memcpy((void *) t + sizeof(*t) + cgid_len, data, len);
108
109	if (blk_tracer)
110	trace_buffer_unlock_commit(tr: blk_tr, buffer, event, trace_ctx);
111	}
112	}
113
114	/*
115	* Send out a notify for this process, if we haven't done so since a trace
116	* started
117	*/
118	static void trace_note_tsk(struct task_struct *tsk)
119	{
120	unsigned long flags;
121	struct blk_trace *bt;
122
123	tsk->btrace_seq = blktrace_seq;
124	raw_spin_lock_irqsave(&running_trace_lock, flags);
125	list_for_each_entry(bt, &running_trace_list, running_list) {
126	trace_note(bt, pid: tsk->pid, BLK_TN_PROCESS, data: tsk->comm,
127	len: sizeof(tsk->comm), cgid: 0);
128	}
129	raw_spin_unlock_irqrestore(&running_trace_lock, flags);
130	}
131
132	static void trace_note_time(struct blk_trace *bt)
133	{
134	struct timespec64 now;
135	unsigned long flags;
136	u32 words[2];
137
138	/* need to check user space to see if this breaks in y2038 or y2106 */
139	ktime_get_real_ts64(tv: &now);
140	words[0] = (u32)now.tv_sec;
141	words[1] = now.tv_nsec;
142
143	local_irq_save(flags);
144	trace_note(bt, pid: 0, BLK_TN_TIMESTAMP, data: words, len: sizeof(words), cgid: 0);
145	local_irq_restore(flags);
146	}
147
148	void __blk_trace_note_message(struct blk_trace *bt,
149	struct cgroup_subsys_state *css, const char *fmt, ...)
150	{
151	int n;
152	va_list args;
153	unsigned long flags;
154	char *buf;
155	u64 cgid = 0;
156
157	if (unlikely(bt->trace_state != Blktrace_running &&
158	!blk_tracer_enabled))
159	return;
160
161	/*
162	* If the BLK_TC_NOTIFY action mask isn't set, don't send any note
163	* message to the trace.
164	*/
165	if (!(bt->act_mask & BLK_TC_NOTIFY))
166	return;
167
168	local_irq_save(flags);
169	buf = this_cpu_ptr(bt->msg_data);
170	va_start(args, fmt);
171	n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
172	va_end(args);
173
174	#ifdef CONFIG_BLK_CGROUP
175	if (css && (blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
176	cgid = cgroup_id(cgrp: css->cgroup);
177	else
178	cgid = 1;
179	#endif
180	trace_note(bt, current->pid, BLK_TN_MESSAGE, data: buf, len: n, cgid);
181	local_irq_restore(flags);
182	}
183	EXPORT_SYMBOL_GPL(__blk_trace_note_message);
184
185	static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
186	pid_t pid)
187	{
188	if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
189	return 1;
190	if (sector && (sector < bt->start_lba || sector > bt->end_lba))
191	return 1;
192	if (bt->pid && pid != bt->pid)
193	return 1;
194
195	return 0;
196	}
197
198	/*
199	* Data direction bit lookup
200	*/
201	static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
202	BLK_TC_ACT(BLK_TC_WRITE) };
203
204	#define BLK_TC_RAHEAD BLK_TC_AHEAD
205	#define BLK_TC_PREFLUSH BLK_TC_FLUSH
206
207	/* The ilog2() calls fall out because they're constant */
208	#define MASK_TC_BIT(rw, __name) ((__force u32)(rw & REQ_ ## __name) << \
209	(ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))
210
211	/*
212	* The worker for the various blk_add_trace*() types. Fills out a
213	* blk_io_trace structure and places it in a per-cpu subbuffer.
214	*/
215	static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
216	const blk_opf_t opf, u32 what, int error,
217	int pdu_len, void *pdu_data, u64 cgid)
218	{
219	struct task_struct *tsk = current;
220	struct ring_buffer_event *event = NULL;
221	struct trace_buffer *buffer = NULL;
222	struct blk_io_trace *t;
223	unsigned long flags = 0;
224	unsigned long *sequence;
225	unsigned int trace_ctx = 0;
226	pid_t pid;
227	int cpu;
228	bool blk_tracer = blk_tracer_enabled;
229	ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
230	const enum req_op op = opf & REQ_OP_MASK;
231
232	if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
233	return;
234
235	what |= ddir_act[op_is_write(op) ? WRITE : READ];
236	what |= MASK_TC_BIT(opf, SYNC);
237	what |= MASK_TC_BIT(opf, RAHEAD);
238	what |= MASK_TC_BIT(opf, META);
239	what |= MASK_TC_BIT(opf, PREFLUSH);
240	what |= MASK_TC_BIT(opf, FUA);
241	if (op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE)
242	what |= BLK_TC_ACT(BLK_TC_DISCARD);
243	if (op == REQ_OP_FLUSH)
244	what |= BLK_TC_ACT(BLK_TC_FLUSH);
245	if (cgid)
246	what |= __BLK_TA_CGROUP;
247
248	pid = tsk->pid;
249	if (act_log_check(bt, what, sector, pid))
250	return;
251	cpu = raw_smp_processor_id();
252
253	if (blk_tracer) {
254	tracing_record_cmdline(current);
255
256	buffer = blk_tr->array_buffer.buffer;
257	trace_ctx = tracing_gen_ctx_flags(irqflags: 0);
258	event = trace_buffer_lock_reserve(buffer, type: TRACE_BLK,
259	len: sizeof(*t) + pdu_len + cgid_len,
260	trace_ctx);
261	if (!event)
262	return;
263	t = ring_buffer_event_data(event);
264	goto record_it;
265	}
266
267	if (unlikely(tsk->btrace_seq != blktrace_seq))
268	trace_note_tsk(tsk);
269
270	/*
271	* A word about the locking here - we disable interrupts to reserve
272	* some space in the relay per-cpu buffer, to prevent an irq
273	* from coming in and stepping on our toes.
274	*/
275	local_irq_save(flags);
276	t = relay_reserve(chan: bt->rchan, length: sizeof(*t) + pdu_len + cgid_len);
277	if (t) {
278	sequence = per_cpu_ptr(bt->sequence, cpu);
279
280	t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
281	t->sequence = ++(*sequence);
282	t->time = ktime_to_ns(kt: ktime_get());
283	record_it:
284	/*
285	* These two are not needed in ftrace as they are in the
286	* generic trace_entry, filled by tracing_generic_entry_update,
287	* but for the trace_event->bin() synthesizer benefit we do it
288	* here too.
289	*/
290	t->cpu = cpu;
291	t->pid = pid;
292
293	t->sector = sector;
294	t->bytes = bytes;
295	t->action = what;
296	t->device = bt->dev;
297	t->error = error;
298	t->pdu_len = pdu_len + cgid_len;
299
300	if (cgid_len)
301	memcpy((void *)t + sizeof(*t), &cgid, cgid_len);
302	if (pdu_len)
303	memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len);
304
305	if (blk_tracer) {
306	trace_buffer_unlock_commit(tr: blk_tr, buffer, event, trace_ctx);
307	return;
308	}
309	}
310
311	local_irq_restore(flags);
312	}
313
314	static void blk_trace_free(struct request_queue *q, struct blk_trace *bt)
315	{
316	relay_close(chan: bt->rchan);
317
318	/*
319	* If 'bt->dir' is not set, then both 'dropped' and 'msg' are created
320	* under 'q->debugfs_dir', thus lookup and remove them.
321	*/
322	if (!bt->dir) {
323	debugfs_lookup_and_remove(name: "dropped", parent: q->debugfs_dir);
324	debugfs_lookup_and_remove(name: "msg", parent: q->debugfs_dir);
325	} else {
326	debugfs_remove(dentry: bt->dir);
327	}
328	free_percpu(pdata: bt->sequence);
329	free_percpu(pdata: bt->msg_data);
330	kfree(objp: bt);
331	}
332
333	static void get_probe_ref(void)
334	{
335	mutex_lock(&blk_probe_mutex);
336	if (++blk_probes_ref == 1)
337	blk_register_tracepoints();
338	mutex_unlock(lock: &blk_probe_mutex);
339	}
340
341	static void put_probe_ref(void)
342	{
343	mutex_lock(&blk_probe_mutex);
344	if (!--blk_probes_ref)
345	blk_unregister_tracepoints();
346	mutex_unlock(lock: &blk_probe_mutex);
347	}
348
349	static int blk_trace_start(struct blk_trace *bt)
350	{
351	if (bt->trace_state != Blktrace_setup &&
352	bt->trace_state != Blktrace_stopped)
353	return -EINVAL;
354
355	blktrace_seq++;
356	smp_mb();
357	bt->trace_state = Blktrace_running;
358	raw_spin_lock_irq(&running_trace_lock);
359	list_add(new: &bt->running_list, head: &running_trace_list);
360	raw_spin_unlock_irq(&running_trace_lock);
361	trace_note_time(bt);
362
363	return 0;
364	}
365
366	static int blk_trace_stop(struct blk_trace *bt)
367	{
368	if (bt->trace_state != Blktrace_running)
369	return -EINVAL;
370
371	bt->trace_state = Blktrace_stopped;
372	raw_spin_lock_irq(&running_trace_lock);
373	list_del_init(entry: &bt->running_list);
374	raw_spin_unlock_irq(&running_trace_lock);
375	relay_flush(chan: bt->rchan);
376
377	return 0;
378	}
379
380	static void blk_trace_cleanup(struct request_queue *q, struct blk_trace *bt)
381	{
382	blk_trace_stop(bt);
383	synchronize_rcu();
384	blk_trace_free(q, bt);
385	put_probe_ref();
386	}
387
388	static int __blk_trace_remove(struct request_queue *q)
389	{
390	struct blk_trace *bt;
391
392	bt = rcu_replace_pointer(q->blk_trace, NULL,
393	lockdep_is_held(&q->debugfs_mutex));
394	if (!bt)
395	return -EINVAL;
396
397	blk_trace_cleanup(q, bt);
398
399	return 0;
400	}
401
402	int blk_trace_remove(struct request_queue *q)
403	{
404	int ret;
405
406	mutex_lock(&q->debugfs_mutex);
407	ret = __blk_trace_remove(q);
408	mutex_unlock(lock: &q->debugfs_mutex);
409
410	return ret;
411	}
412	EXPORT_SYMBOL_GPL(blk_trace_remove);
413
414	static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
415	size_t count, loff_t *ppos)
416	{
417	struct blk_trace *bt = filp->private_data;
418	char buf[16];
419
420	snprintf(buf, size: sizeof(buf), fmt: "%u\n", atomic_read(v: &bt->dropped));
421
422	return simple_read_from_buffer(to: buffer, count, ppos, from: buf, strlen(buf));
423	}
424
425	static const struct file_operations blk_dropped_fops = {
426	.owner = THIS_MODULE,
427	.open = simple_open,
428	.read = blk_dropped_read,
429	.llseek = default_llseek,
430	};
431
432	static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
433	size_t count, loff_t *ppos)
434	{
435	char *msg;
436	struct blk_trace *bt;
437
438	if (count >= BLK_TN_MAX_MSG)
439	return -EINVAL;
440
441	msg = memdup_user_nul(buffer, count);
442	if (IS_ERR(ptr: msg))
443	return PTR_ERR(ptr: msg);
444
445	bt = filp->private_data;
446	__blk_trace_note_message(bt, NULL, "%s", msg);
447	kfree(objp: msg);
448
449	return count;
450	}
451
452	static const struct file_operations blk_msg_fops = {
453	.owner = THIS_MODULE,
454	.open = simple_open,
455	.write = blk_msg_write,
456	.llseek = noop_llseek,
457	};
458
459	/*
460	* Keep track of how many times we encountered a full subbuffer, to aid
461	* the user space app in telling how many lost events there were.
462	*/
463	static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
464	void *prev_subbuf, size_t prev_padding)
465	{
466	struct blk_trace *bt;
467
468	if (!relay_buf_full(buf))
469	return 1;
470
471	bt = buf->chan->private_data;
472	atomic_inc(v: &bt->dropped);
473	return 0;
474	}
475
476	static int blk_remove_buf_file_callback(struct dentry *dentry)
477	{
478	debugfs_remove(dentry);
479
480	return 0;
481	}
482
483	static struct dentry *blk_create_buf_file_callback(const char *filename,
484	struct dentry *parent,
485	umode_t mode,
486	struct rchan_buf *buf,
487	int *is_global)
488	{
489	return debugfs_create_file(name: filename, mode, parent, data: buf,
490	fops: &relay_file_operations);
491	}
492
493	static const struct rchan_callbacks blk_relay_callbacks = {
494	.subbuf_start = blk_subbuf_start_callback,
495	.create_buf_file = blk_create_buf_file_callback,
496	.remove_buf_file = blk_remove_buf_file_callback,
497	};
498
499	static void blk_trace_setup_lba(struct blk_trace *bt,
500	struct block_device *bdev)
501	{
502	if (bdev) {
503	bt->start_lba = bdev->bd_start_sect;
504	bt->end_lba = bdev->bd_start_sect + bdev_nr_sectors(bdev);
505	} else {
506	bt->start_lba = 0;
507	bt->end_lba = -1ULL;
508	}
509	}
510
511	/*
512	* Setup everything required to start tracing
513	*/
514	static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
515	struct block_device *bdev,
516	struct blk_user_trace_setup *buts)
517	{
518	struct blk_trace *bt = NULL;
519	struct dentry *dir = NULL;
520	int ret;
521
522	lockdep_assert_held(&q->debugfs_mutex);
523
524	if (!buts->buf_size || !buts->buf_nr)
525	return -EINVAL;
526
527	strncpy(p: buts->name, q: name, BLKTRACE_BDEV_SIZE);
528	buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';
529
530	/*
531	* some device names have larger paths - convert the slashes
532	* to underscores for this to work as expected
533	*/
534	strreplace(str: buts->name, old: '/', new: '_');
535
536	/*
537	* bdev can be NULL, as with scsi-generic, this is a helpful as
538	* we can be.
539	*/
540	if (rcu_dereference_protected(q->blk_trace,
541	lockdep_is_held(&q->debugfs_mutex))) {
542	pr_warn("Concurrent blktraces are not allowed on %s\n",
543	buts->name);
544	return -EBUSY;
545	}
546
547	bt = kzalloc(size: sizeof(*bt), GFP_KERNEL);
548	if (!bt)
549	return -ENOMEM;
550
551	ret = -ENOMEM;
552	bt->sequence = alloc_percpu(unsigned long);
553	if (!bt->sequence)
554	goto err;
555
556	bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, align: __alignof__(char));
557	if (!bt->msg_data)
558	goto err;
559
560	/*
561	* When tracing the whole disk reuse the existing debugfs directory
562	* created by the block layer on init. For partitions block devices,
563	* and scsi-generic block devices we create a temporary new debugfs
564	* directory that will be removed once the trace ends.
565	*/
566	if (bdev && !bdev_is_partition(bdev))
567	dir = q->debugfs_dir;
568	else
569	bt->dir = dir = debugfs_create_dir(name: buts->name, parent: blk_debugfs_root);
570
571	/*
572	* As blktrace relies on debugfs for its interface the debugfs directory
573	* is required, contrary to the usual mantra of not checking for debugfs
574	* files or directories.
575	*/
576	if (IS_ERR_OR_NULL(ptr: dir)) {
577	pr_warn("debugfs_dir not present for %s so skipping\n",
578	buts->name);
579	ret = -ENOENT;
580	goto err;
581	}
582
583	bt->dev = dev;
584	atomic_set(v: &bt->dropped, i: 0);
585	INIT_LIST_HEAD(list: &bt->running_list);
586
587	ret = -EIO;
588	debugfs_create_file(name: "dropped", mode: 0444, parent: dir, data: bt, fops: &blk_dropped_fops);
589	debugfs_create_file(name: "msg", mode: 0222, parent: dir, data: bt, fops: &blk_msg_fops);
590
591	bt->rchan = relay_open(base_filename: "trace", parent: dir, subbuf_size: buts->buf_size,
592	n_subbufs: buts->buf_nr, cb: &blk_relay_callbacks, private_data: bt);
593	if (!bt->rchan)
594	goto err;
595
596	bt->act_mask = buts->act_mask;
597	if (!bt->act_mask)
598	bt->act_mask = (u16) -1;
599
600	blk_trace_setup_lba(bt, bdev);
601
602	/* overwrite with user settings */
603	if (buts->start_lba)
604	bt->start_lba = buts->start_lba;
605	if (buts->end_lba)
606	bt->end_lba = buts->end_lba;
607
608	bt->pid = buts->pid;
609	bt->trace_state = Blktrace_setup;
610
611	rcu_assign_pointer(q->blk_trace, bt);
612	get_probe_ref();
613
614	ret = 0;
615	err:
616	if (ret)
617	blk_trace_free(q, bt);
618	return ret;
619	}
620
621	static int __blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
622	struct block_device *bdev, char __user *arg)
623	{
624	struct blk_user_trace_setup buts;
625	int ret;
626
627	ret = copy_from_user(to: &buts, from: arg, n: sizeof(buts));
628	if (ret)
629	return -EFAULT;
630
631	ret = do_blk_trace_setup(q, name, dev, bdev, buts: &buts);
632	if (ret)
633	return ret;
634
635	if (copy_to_user(to: arg, from: &buts, n: sizeof(buts))) {
636	__blk_trace_remove(q);
637	return -EFAULT;
638	}
639	return 0;
640	}
641
642	int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
643	struct block_device *bdev,
644	char __user *arg)
645	{
646	int ret;
647
648	mutex_lock(&q->debugfs_mutex);
649	ret = __blk_trace_setup(q, name, dev, bdev, arg);
650	mutex_unlock(lock: &q->debugfs_mutex);
651
652	return ret;
653	}
654	EXPORT_SYMBOL_GPL(blk_trace_setup);
655
656	#if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
657	static int compat_blk_trace_setup(struct request_queue *q, char *name,
658	dev_t dev, struct block_device *bdev,
659	char __user *arg)
660	{
661	struct blk_user_trace_setup buts;
662	struct compat_blk_user_trace_setup cbuts;
663	int ret;
664
665	if (copy_from_user(to: &cbuts, from: arg, n: sizeof(cbuts)))
666	return -EFAULT;
667
668	buts = (struct blk_user_trace_setup) {
669	.act_mask = cbuts.act_mask,
670	.buf_size = cbuts.buf_size,
671	.buf_nr = cbuts.buf_nr,
672	.start_lba = cbuts.start_lba,
673	.end_lba = cbuts.end_lba,
674	.pid = cbuts.pid,
675	};
676
677	ret = do_blk_trace_setup(q, name, dev, bdev, buts: &buts);
678	if (ret)
679	return ret;
680
681	if (copy_to_user(to: arg, from: &buts.name, ARRAY_SIZE(buts.name))) {
682	__blk_trace_remove(q);
683	return -EFAULT;
684	}
685
686	return 0;
687	}
688	#endif
689
690	static int __blk_trace_startstop(struct request_queue *q, int start)
691	{
692	struct blk_trace *bt;
693
694	bt = rcu_dereference_protected(q->blk_trace,
695	lockdep_is_held(&q->debugfs_mutex));
696	if (bt == NULL)
697	return -EINVAL;
698
699	if (start)
700	return blk_trace_start(bt);
701	else
702	return blk_trace_stop(bt);
703	}
704
705	int blk_trace_startstop(struct request_queue *q, int start)
706	{
707	int ret;
708
709	mutex_lock(&q->debugfs_mutex);
710	ret = __blk_trace_startstop(q, start);
711	mutex_unlock(lock: &q->debugfs_mutex);
712
713	return ret;
714	}
715	EXPORT_SYMBOL_GPL(blk_trace_startstop);
716
717	/*
718	* When reading or writing the blktrace sysfs files, the references to the
719	* opened sysfs or device files should prevent the underlying block device
720	* from being removed. So no further delete protection is really needed.
721	*/
722
723	/**
724	* blk_trace_ioctl - handle the ioctls associated with tracing
725	* @bdev: the block device
726	* @cmd: the ioctl cmd
727	* @arg: the argument data, if any
728	*
729	**/
730	int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
731	{
732	struct request_queue *q = bdev_get_queue(bdev);
733	int ret, start = 0;
734	char b[BDEVNAME_SIZE];
735
736	mutex_lock(&q->debugfs_mutex);
737
738	switch (cmd) {
739	case BLKTRACESETUP:
740	snprintf(buf: b, size: sizeof(b), fmt: "%pg", bdev);
741	ret = __blk_trace_setup(q, name: b, dev: bdev->bd_dev, bdev, arg);
742	break;
743	#if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
744	case BLKTRACESETUP32:
745	snprintf(buf: b, size: sizeof(b), fmt: "%pg", bdev);
746	ret = compat_blk_trace_setup(q, name: b, dev: bdev->bd_dev, bdev, arg);
747	break;
748	#endif
749	case BLKTRACESTART:
750	start = 1;
751	fallthrough;
752	case BLKTRACESTOP:
753	ret = __blk_trace_startstop(q, start);
754	break;
755	case BLKTRACETEARDOWN:
756	ret = __blk_trace_remove(q);
757	break;
758	default:
759	ret = -ENOTTY;
760	break;
761	}
762
763	mutex_unlock(lock: &q->debugfs_mutex);
764	return ret;
765	}
766
767	/**
768	* blk_trace_shutdown - stop and cleanup trace structures
769	* @q: the request queue associated with the device
770	*
771	**/
772	void blk_trace_shutdown(struct request_queue *q)
773	{
774	if (rcu_dereference_protected(q->blk_trace,
775	lockdep_is_held(&q->debugfs_mutex)))
776	__blk_trace_remove(q);
777	}
778
779	#ifdef CONFIG_BLK_CGROUP
780	static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
781	{
782	struct cgroup_subsys_state *blkcg_css;
783	struct blk_trace *bt;
784
785	/* We don't use the 'bt' value here except as an optimization... */
786	bt = rcu_dereference_protected(q->blk_trace, 1);
787	if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
788	return 0;
789
790	blkcg_css = bio_blkcg_css(bio);
791	if (!blkcg_css)
792	return 0;
793	return cgroup_id(cgrp: blkcg_css->cgroup);
794	}
795	#else
796	static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
797	{
798	return 0;
799	}
800	#endif
801
802	static u64
803	blk_trace_request_get_cgid(struct request *rq)
804	{
805	if (!rq->bio)
806	return 0;
807	/* Use the first bio */
808	return blk_trace_bio_get_cgid(q: rq->q, bio: rq->bio);
809	}
810
811	/*
812	* blktrace probes
813	*/
814
815	/**
816	* blk_add_trace_rq - Add a trace for a request oriented action
817	* @rq: the source request
818	* @error: return status to log
819	* @nr_bytes: number of completed bytes
820	* @what: the action
821	* @cgid: the cgroup info
822	*
823	* Description:
824	* Records an action against a request. Will log the bio offset + size.
825	*
826	**/
827	static void blk_add_trace_rq(struct request *rq, blk_status_t error,
828	unsigned int nr_bytes, u32 what, u64 cgid)
829	{
830	struct blk_trace *bt;
831
832	rcu_read_lock();
833	bt = rcu_dereference(rq->q->blk_trace);
834	if (likely(!bt)) {
835	rcu_read_unlock();
836	return;
837	}
838
839	if (blk_rq_is_passthrough(rq))
840	what |= BLK_TC_ACT(BLK_TC_PC);
841	else
842	what |= BLK_TC_ACT(BLK_TC_FS);
843
844	__blk_add_trace(bt, sector: blk_rq_trace_sector(rq), bytes: nr_bytes, opf: rq->cmd_flags,
845	what, error: blk_status_to_errno(status: error), pdu_len: 0, NULL, cgid);
846	rcu_read_unlock();
847	}
848
849	static void blk_add_trace_rq_insert(void *ignore, struct request *rq)
850	{
851	blk_add_trace_rq(rq, error: 0, nr_bytes: blk_rq_bytes(rq), BLK_TA_INSERT,
852	cgid: blk_trace_request_get_cgid(rq));
853	}
854
855	static void blk_add_trace_rq_issue(void *ignore, struct request *rq)
856	{
857	blk_add_trace_rq(rq, error: 0, nr_bytes: blk_rq_bytes(rq), BLK_TA_ISSUE,
858	cgid: blk_trace_request_get_cgid(rq));
859	}
860
861	static void blk_add_trace_rq_merge(void *ignore, struct request *rq)
862	{
863	blk_add_trace_rq(rq, error: 0, nr_bytes: blk_rq_bytes(rq), BLK_TA_BACKMERGE,
864	cgid: blk_trace_request_get_cgid(rq));
865	}
866
867	static void blk_add_trace_rq_requeue(void *ignore, struct request *rq)
868	{
869	blk_add_trace_rq(rq, error: 0, nr_bytes: blk_rq_bytes(rq), BLK_TA_REQUEUE,
870	cgid: blk_trace_request_get_cgid(rq));
871	}
872
873	static void blk_add_trace_rq_complete(void *ignore, struct request *rq,
874	blk_status_t error, unsigned int nr_bytes)
875	{
876	blk_add_trace_rq(rq, error, nr_bytes, BLK_TA_COMPLETE,
877	cgid: blk_trace_request_get_cgid(rq));
878	}
879
880	/**
881	* blk_add_trace_bio - Add a trace for a bio oriented action
882	* @q: queue the io is for
883	* @bio: the source bio
884	* @what: the action
885	* @error: error, if any
886	*
887	* Description:
888	* Records an action against a bio. Will log the bio offset + size.
889	*
890	**/
891	static void blk_add_trace_bio(struct request_queue *q, struct bio *bio,
892	u32 what, int error)
893	{
894	struct blk_trace *bt;
895
896	rcu_read_lock();
897	bt = rcu_dereference(q->blk_trace);
898	if (likely(!bt)) {
899	rcu_read_unlock();
900	return;
901	}
902
903	__blk_add_trace(bt, sector: bio->bi_iter.bi_sector, bytes: bio->bi_iter.bi_size,
904	opf: bio->bi_opf, what, error, pdu_len: 0, NULL,
905	cgid: blk_trace_bio_get_cgid(q, bio));
906	rcu_read_unlock();
907	}
908
909	static void blk_add_trace_bio_bounce(void *ignore, struct bio *bio)
910	{
911	blk_add_trace_bio(q: bio->bi_bdev->bd_disk->queue, bio, BLK_TA_BOUNCE, error: 0);
912	}
913
914	static void blk_add_trace_bio_complete(void *ignore,
915	struct request_queue *q, struct bio *bio)
916	{
917	blk_add_trace_bio(q, bio, BLK_TA_COMPLETE,
918	error: blk_status_to_errno(status: bio->bi_status));
919	}
920
921	static void blk_add_trace_bio_backmerge(void *ignore, struct bio *bio)
922	{
923	blk_add_trace_bio(q: bio->bi_bdev->bd_disk->queue, bio, BLK_TA_BACKMERGE,
924	error: 0);
925	}
926
927	static void blk_add_trace_bio_frontmerge(void *ignore, struct bio *bio)
928	{
929	blk_add_trace_bio(q: bio->bi_bdev->bd_disk->queue, bio, BLK_TA_FRONTMERGE,
930	error: 0);
931	}
932
933	static void blk_add_trace_bio_queue(void *ignore, struct bio *bio)
934	{
935	blk_add_trace_bio(q: bio->bi_bdev->bd_disk->queue, bio, BLK_TA_QUEUE, error: 0);
936	}
937
938	static void blk_add_trace_getrq(void *ignore, struct bio *bio)
939	{
940	blk_add_trace_bio(q: bio->bi_bdev->bd_disk->queue, bio, BLK_TA_GETRQ, error: 0);
941	}
942
943	static void blk_add_trace_plug(void *ignore, struct request_queue *q)
944	{
945	struct blk_trace *bt;
946
947	rcu_read_lock();
948	bt = rcu_dereference(q->blk_trace);
949	if (bt)
950	__blk_add_trace(bt, sector: 0, bytes: 0, opf: 0, BLK_TA_PLUG, error: 0, pdu_len: 0, NULL, cgid: 0);
951	rcu_read_unlock();
952	}
953
954	static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
955	unsigned int depth, bool explicit)
956	{
957	struct blk_trace *bt;
958
959	rcu_read_lock();
960	bt = rcu_dereference(q->blk_trace);
961	if (bt) {
962	__be64 rpdu = cpu_to_be64(depth);
963	u32 what;
964
965	if (explicit)
966	what = BLK_TA_UNPLUG_IO;
967	else
968	what = BLK_TA_UNPLUG_TIMER;
969
970	__blk_add_trace(bt, sector: 0, bytes: 0, opf: 0, what, error: 0, pdu_len: sizeof(rpdu), pdu_data: &rpdu, cgid: 0);
971	}
972	rcu_read_unlock();
973	}
974
975	static void blk_add_trace_split(void *ignore, struct bio *bio, unsigned int pdu)
976	{
977	struct request_queue *q = bio->bi_bdev->bd_disk->queue;
978	struct blk_trace *bt;
979
980	rcu_read_lock();
981	bt = rcu_dereference(q->blk_trace);
982	if (bt) {
983	__be64 rpdu = cpu_to_be64(pdu);
984
985	__blk_add_trace(bt, sector: bio->bi_iter.bi_sector,
986	bytes: bio->bi_iter.bi_size, opf: bio->bi_opf, BLK_TA_SPLIT,
987	error: blk_status_to_errno(status: bio->bi_status),
988	pdu_len: sizeof(rpdu), pdu_data: &rpdu,
989	cgid: blk_trace_bio_get_cgid(q, bio));
990	}
991	rcu_read_unlock();
992	}
993
994	/**
995	* blk_add_trace_bio_remap - Add a trace for a bio-remap operation
996	* @ignore: trace callback data parameter (not used)
997	* @bio: the source bio
998	* @dev: source device
999	* @from: source sector
1000	*
1001	* Called after a bio is remapped to a different device and/or sector.
1002	**/
1003	static void blk_add_trace_bio_remap(void *ignore, struct bio *bio, dev_t dev,
1004	sector_t from)
1005	{
1006	struct request_queue *q = bio->bi_bdev->bd_disk->queue;
1007	struct blk_trace *bt;
1008	struct blk_io_trace_remap r;
1009
1010	rcu_read_lock();
1011	bt = rcu_dereference(q->blk_trace);
1012	if (likely(!bt)) {
1013	rcu_read_unlock();
1014	return;
1015	}
1016
1017	r.device_from = cpu_to_be32(dev);
1018	r.device_to = cpu_to_be32(bio_dev(bio));
1019	r.sector_from = cpu_to_be64(from);
1020
1021	__blk_add_trace(bt, sector: bio->bi_iter.bi_sector, bytes: bio->bi_iter.bi_size,
1022	opf: bio->bi_opf, BLK_TA_REMAP,
1023	error: blk_status_to_errno(status: bio->bi_status),
1024	pdu_len: sizeof(r), pdu_data: &r, cgid: blk_trace_bio_get_cgid(q, bio));
1025	rcu_read_unlock();
1026	}
1027
1028	/**
1029	* blk_add_trace_rq_remap - Add a trace for a request-remap operation
1030	* @ignore: trace callback data parameter (not used)
1031	* @rq: the source request
1032	* @dev: target device
1033	* @from: source sector
1034	*
1035	* Description:
1036	* Device mapper remaps request to other devices.
1037	* Add a trace for that action.
1038	*
1039	**/
1040	static void blk_add_trace_rq_remap(void *ignore, struct request *rq, dev_t dev,
1041	sector_t from)
1042	{
1043	struct blk_trace *bt;
1044	struct blk_io_trace_remap r;
1045
1046	rcu_read_lock();
1047	bt = rcu_dereference(rq->q->blk_trace);
1048	if (likely(!bt)) {
1049	rcu_read_unlock();
1050	return;
1051	}
1052
1053	r.device_from = cpu_to_be32(dev);
1054	r.device_to = cpu_to_be32(disk_devt(rq->q->disk));
1055	r.sector_from = cpu_to_be64(from);
1056
1057	__blk_add_trace(bt, sector: blk_rq_pos(rq), bytes: blk_rq_bytes(rq),
1058	opf: rq->cmd_flags, BLK_TA_REMAP, error: 0,
1059	pdu_len: sizeof(r), pdu_data: &r, cgid: blk_trace_request_get_cgid(rq));
1060	rcu_read_unlock();
1061	}
1062
1063	/**
1064	* blk_add_driver_data - Add binary message with driver-specific data
1065	* @rq: io request
1066	* @data: driver-specific data
1067	* @len: length of driver-specific data
1068	*
1069	* Description:
1070	* Some drivers might want to write driver-specific data per request.
1071	*
1072	**/
1073	void blk_add_driver_data(struct request *rq, void *data, size_t len)
1074	{
1075	struct blk_trace *bt;
1076
1077	rcu_read_lock();
1078	bt = rcu_dereference(rq->q->blk_trace);
1079	if (likely(!bt)) {
1080	rcu_read_unlock();
1081	return;
1082	}
1083
1084	__blk_add_trace(bt, sector: blk_rq_trace_sector(rq), bytes: blk_rq_bytes(rq), opf: 0,
1085	BLK_TA_DRV_DATA, error: 0, pdu_len: len, pdu_data: data,
1086	cgid: blk_trace_request_get_cgid(rq));
1087	rcu_read_unlock();
1088	}
1089	EXPORT_SYMBOL_GPL(blk_add_driver_data);
1090
1091	static void blk_register_tracepoints(void)
1092	{
1093	int ret;
1094
1095	ret = register_trace_block_rq_insert(probe: blk_add_trace_rq_insert, NULL);
1096	WARN_ON(ret);
1097	ret = register_trace_block_rq_issue(probe: blk_add_trace_rq_issue, NULL);
1098	WARN_ON(ret);
1099	ret = register_trace_block_rq_merge(probe: blk_add_trace_rq_merge, NULL);
1100	WARN_ON(ret);
1101	ret = register_trace_block_rq_requeue(probe: blk_add_trace_rq_requeue, NULL);
1102	WARN_ON(ret);
1103	ret = register_trace_block_rq_complete(probe: blk_add_trace_rq_complete, NULL);
1104	WARN_ON(ret);
1105	ret = register_trace_block_bio_bounce(probe: blk_add_trace_bio_bounce, NULL);
1106	WARN_ON(ret);
1107	ret = register_trace_block_bio_complete(probe: blk_add_trace_bio_complete, NULL);
1108	WARN_ON(ret);
1109	ret = register_trace_block_bio_backmerge(probe: blk_add_trace_bio_backmerge, NULL);
1110	WARN_ON(ret);
1111	ret = register_trace_block_bio_frontmerge(probe: blk_add_trace_bio_frontmerge, NULL);
1112	WARN_ON(ret);
1113	ret = register_trace_block_bio_queue(probe: blk_add_trace_bio_queue, NULL);
1114	WARN_ON(ret);
1115	ret = register_trace_block_getrq(probe: blk_add_trace_getrq, NULL);
1116	WARN_ON(ret);
1117	ret = register_trace_block_plug(probe: blk_add_trace_plug, NULL);
1118	WARN_ON(ret);
1119	ret = register_trace_block_unplug(probe: blk_add_trace_unplug, NULL);
1120	WARN_ON(ret);
1121	ret = register_trace_block_split(probe: blk_add_trace_split, NULL);
1122	WARN_ON(ret);
1123	ret = register_trace_block_bio_remap(probe: blk_add_trace_bio_remap, NULL);
1124	WARN_ON(ret);
1125	ret = register_trace_block_rq_remap(probe: blk_add_trace_rq_remap, NULL);
1126	WARN_ON(ret);
1127	}
1128
1129	static void blk_unregister_tracepoints(void)
1130	{
1131	unregister_trace_block_rq_remap(probe: blk_add_trace_rq_remap, NULL);
1132	unregister_trace_block_bio_remap(probe: blk_add_trace_bio_remap, NULL);
1133	unregister_trace_block_split(probe: blk_add_trace_split, NULL);
1134	unregister_trace_block_unplug(probe: blk_add_trace_unplug, NULL);
1135	unregister_trace_block_plug(probe: blk_add_trace_plug, NULL);
1136	unregister_trace_block_getrq(probe: blk_add_trace_getrq, NULL);
1137	unregister_trace_block_bio_queue(probe: blk_add_trace_bio_queue, NULL);
1138	unregister_trace_block_bio_frontmerge(probe: blk_add_trace_bio_frontmerge, NULL);
1139	unregister_trace_block_bio_backmerge(probe: blk_add_trace_bio_backmerge, NULL);
1140	unregister_trace_block_bio_complete(probe: blk_add_trace_bio_complete, NULL);
1141	unregister_trace_block_bio_bounce(probe: blk_add_trace_bio_bounce, NULL);
1142	unregister_trace_block_rq_complete(probe: blk_add_trace_rq_complete, NULL);
1143	unregister_trace_block_rq_requeue(probe: blk_add_trace_rq_requeue, NULL);
1144	unregister_trace_block_rq_merge(probe: blk_add_trace_rq_merge, NULL);
1145	unregister_trace_block_rq_issue(probe: blk_add_trace_rq_issue, NULL);
1146	unregister_trace_block_rq_insert(probe: blk_add_trace_rq_insert, NULL);
1147
1148	tracepoint_synchronize_unregister();
1149	}
1150
1151	/*
1152	* struct blk_io_tracer formatting routines
1153	*/
1154
1155	static void fill_rwbs(char *rwbs, const struct blk_io_trace *t)
1156	{
1157	int i = 0;
1158	int tc = t->action >> BLK_TC_SHIFT;
1159
1160	if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1161	rwbs[i++] = 'N';
1162	goto out;
1163	}
1164
1165	if (tc & BLK_TC_FLUSH)
1166	rwbs[i++] = 'F';
1167
1168	if (tc & BLK_TC_DISCARD)
1169	rwbs[i++] = 'D';
1170	else if (tc & BLK_TC_WRITE)
1171	rwbs[i++] = 'W';
1172	else if (t->bytes)
1173	rwbs[i++] = 'R';
1174	else
1175	rwbs[i++] = 'N';
1176
1177	if (tc & BLK_TC_FUA)
1178	rwbs[i++] = 'F';
1179	if (tc & BLK_TC_AHEAD)
1180	rwbs[i++] = 'A';
1181	if (tc & BLK_TC_SYNC)
1182	rwbs[i++] = 'S';
1183	if (tc & BLK_TC_META)
1184	rwbs[i++] = 'M';
1185	out:
1186	rwbs[i] = '\0';
1187	}
1188
1189	static inline
1190	const struct blk_io_trace *te_blk_io_trace(const struct trace_entry *ent)
1191	{
1192	return (const struct blk_io_trace *)ent;
1193	}
1194
1195	static inline const void *pdu_start(const struct trace_entry *ent, bool has_cg)
1196	{
1197	return (void *)(te_blk_io_trace(ent) + 1) + (has_cg ? sizeof(u64) : 0);
1198	}
1199
1200	static inline u64 t_cgid(const struct trace_entry *ent)
1201	{
1202	return *(u64 *)(te_blk_io_trace(ent) + 1);
1203	}
1204
1205	static inline int pdu_real_len(const struct trace_entry *ent, bool has_cg)
1206	{
1207	return te_blk_io_trace(ent)->pdu_len - (has_cg ? sizeof(u64) : 0);
1208	}
1209
1210	static inline u32 t_action(const struct trace_entry *ent)
1211	{
1212	return te_blk_io_trace(ent)->action;
1213	}
1214
1215	static inline u32 t_bytes(const struct trace_entry *ent)
1216	{
1217	return te_blk_io_trace(ent)->bytes;
1218	}
1219
1220	static inline u32 t_sec(const struct trace_entry *ent)
1221	{
1222	return te_blk_io_trace(ent)->bytes >> 9;
1223	}
1224
1225	static inline unsigned long long t_sector(const struct trace_entry *ent)
1226	{
1227	return te_blk_io_trace(ent)->sector;
1228	}
1229
1230	static inline __u16 t_error(const struct trace_entry *ent)
1231	{
1232	return te_blk_io_trace(ent)->error;
1233	}
1234
1235	static __u64 get_pdu_int(const struct trace_entry *ent, bool has_cg)
1236	{
1237	const __be64 *val = pdu_start(ent, has_cg);
1238	return be64_to_cpu(*val);
1239	}
1240
1241	typedef void (blk_log_action_t) (struct trace_iterator *iter, const char *act,
1242	bool has_cg);
1243
1244	static void blk_log_action_classic(struct trace_iterator *iter, const char *act,
1245	bool has_cg)
1246	{
1247	char rwbs[RWBS_LEN];
1248	unsigned long long ts = iter->ts;
1249	unsigned long nsec_rem = do_div(ts, NSEC_PER_SEC);
1250	unsigned secs = (unsigned long)ts;
1251	const struct blk_io_trace *t = te_blk_io_trace(ent: iter->ent);
1252
1253	fill_rwbs(rwbs, t);
1254
1255	trace_seq_printf(s: &iter->seq,
1256	fmt: "%3d,%-3d %2d %5d.%09lu %5u %2s %3s ",
1257	MAJOR(t->device), MINOR(t->device), iter->cpu,
1258	secs, nsec_rem, iter->ent->pid, act, rwbs);
1259	}
1260
1261	static void blk_log_action(struct trace_iterator *iter, const char *act,
1262	bool has_cg)
1263	{
1264	char rwbs[RWBS_LEN];
1265	const struct blk_io_trace *t = te_blk_io_trace(ent: iter->ent);
1266
1267	fill_rwbs(rwbs, t);
1268	if (has_cg) {
1269	u64 id = t_cgid(ent: iter->ent);
1270
1271	if (blk_tracer_flags.val & TRACE_BLK_OPT_CGNAME) {
1272	char blkcg_name_buf[NAME_MAX + 1] = "<...>";
1273
1274	cgroup_path_from_kernfs_id(id, buf: blkcg_name_buf,
1275	buflen: sizeof(blkcg_name_buf));
1276	trace_seq_printf(s: &iter->seq, fmt: "%3d,%-3d %s %2s %3s ",
1277	MAJOR(t->device), MINOR(t->device),
1278	blkcg_name_buf, act, rwbs);
1279	} else {
1280	/*
1281	* The cgid portion used to be "INO,GEN". Userland
1282	* builds a FILEID_INO32_GEN fid out of them and
1283	* opens the cgroup using open_by_handle_at(2).
1284	* While 32bit ino setups are still the same, 64bit
1285	* ones now use the 64bit ino as the whole ID and
1286	* no longer use generation.
1287	*
1288	* Regardless of the content, always output
1289	* "LOW32,HIGH32" so that FILEID_INO32_GEN fid can
1290	* be mapped back to @id on both 64 and 32bit ino
1291	* setups. See __kernfs_fh_to_dentry().
1292	*/
1293	trace_seq_printf(s: &iter->seq,
1294	fmt: "%3d,%-3d %llx,%-llx %2s %3s ",
1295	MAJOR(t->device), MINOR(t->device),
1296	id & U32_MAX, id >> 32, act, rwbs);
1297	}
1298	} else
1299	trace_seq_printf(s: &iter->seq, fmt: "%3d,%-3d %2s %3s ",
1300	MAJOR(t->device), MINOR(t->device), act, rwbs);
1301	}
1302
1303	static void blk_log_dump_pdu(struct trace_seq *s,
1304	const struct trace_entry *ent, bool has_cg)
1305	{
1306	const unsigned char *pdu_buf;
1307	int pdu_len;
1308	int i, end;
1309
1310	pdu_buf = pdu_start(ent, has_cg);
1311	pdu_len = pdu_real_len(ent, has_cg);
1312
1313	if (!pdu_len)
1314	return;
1315
1316	/* find the last zero that needs to be printed */
1317	for (end = pdu_len - 1; end >= 0; end--)
1318	if (pdu_buf[end])
1319	break;
1320	end++;
1321
1322	trace_seq_putc(s, c: '(');
1323
1324	for (i = 0; i < pdu_len; i++) {
1325
1326	trace_seq_printf(s, fmt: "%s%02x",
1327	i == 0 ? "" : " ", pdu_buf[i]);
1328
1329	/*
1330	* stop when the rest is just zeros and indicate so
1331	* with a ".." appended
1332	*/
1333	if (i == end && end != pdu_len - 1) {
1334	trace_seq_puts(s, str: " ..) ");
1335	return;
1336	}
1337	}
1338
1339	trace_seq_puts(s, str: ") ");
1340	}
1341
1342	static void blk_log_generic(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1343	{
1344	char cmd[TASK_COMM_LEN];
1345
1346	trace_find_cmdline(pid: ent->pid, comm: cmd);
1347
1348	if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1349	trace_seq_printf(s, fmt: "%u ", t_bytes(ent));
1350	blk_log_dump_pdu(s, ent, has_cg);
1351	trace_seq_printf(s, fmt: "[%s]\n", cmd);
1352	} else {
1353	if (t_sec(ent))
1354	trace_seq_printf(s, fmt: "%llu + %u [%s]\n",
1355	t_sector(ent), t_sec(ent), cmd);
1356	else
1357	trace_seq_printf(s, fmt: "[%s]\n", cmd);
1358	}
1359	}
1360
1361	static void blk_log_with_error(struct trace_seq *s,
1362	const struct trace_entry *ent, bool has_cg)
1363	{
1364	if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
1365	blk_log_dump_pdu(s, ent, has_cg);
1366	trace_seq_printf(s, fmt: "[%d]\n", t_error(ent));
1367	} else {
1368	if (t_sec(ent))
1369	trace_seq_printf(s, fmt: "%llu + %u [%d]\n",
1370	t_sector(ent),
1371	t_sec(ent), t_error(ent));
1372	else
1373	trace_seq_printf(s, fmt: "%llu [%d]\n",
1374	t_sector(ent), t_error(ent));
1375	}
1376	}
1377
1378	static void blk_log_remap(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1379	{
1380	const struct blk_io_trace_remap *__r = pdu_start(ent, has_cg);
1381
1382	trace_seq_printf(s, fmt: "%llu + %u <- (%d,%d) %llu\n",
1383	t_sector(ent), t_sec(ent),
1384	MAJOR(be32_to_cpu(__r->device_from)),
1385	MINOR(be32_to_cpu(__r->device_from)),
1386	be64_to_cpu(__r->sector_from));
1387	}
1388
1389	static void blk_log_plug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1390	{
1391	char cmd[TASK_COMM_LEN];
1392
1393	trace_find_cmdline(pid: ent->pid, comm: cmd);
1394
1395	trace_seq_printf(s, fmt: "[%s]\n", cmd);
1396	}
1397
1398	static void blk_log_unplug(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1399	{
1400	char cmd[TASK_COMM_LEN];
1401
1402	trace_find_cmdline(pid: ent->pid, comm: cmd);
1403
1404	trace_seq_printf(s, fmt: "[%s] %llu\n", cmd, get_pdu_int(ent, has_cg));
1405	}
1406
1407	static void blk_log_split(struct trace_seq *s, const struct trace_entry *ent, bool has_cg)
1408	{
1409	char cmd[TASK_COMM_LEN];
1410
1411	trace_find_cmdline(pid: ent->pid, comm: cmd);
1412
1413	trace_seq_printf(s, fmt: "%llu / %llu [%s]\n", t_sector(ent),
1414	get_pdu_int(ent, has_cg), cmd);
1415	}
1416
1417	static void blk_log_msg(struct trace_seq *s, const struct trace_entry *ent,
1418	bool has_cg)
1419	{
1420
1421	trace_seq_putmem(s, mem: pdu_start(ent, has_cg),
1422	len: pdu_real_len(ent, has_cg));
1423	trace_seq_putc(s, c: '\n');
1424	}
1425
1426	/*
1427	* struct tracer operations
1428	*/
1429
1430	static void blk_tracer_print_header(struct seq_file *m)
1431	{
1432	if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1433	return;
1434	seq_puts(m, s: "# DEV CPU TIMESTAMP PID ACT FLG\n"
1435	"# | | | | | |\n");
1436	}
1437
1438	static void blk_tracer_start(struct trace_array *tr)
1439	{
1440	blk_tracer_enabled = true;
1441	}
1442
1443	static int blk_tracer_init(struct trace_array *tr)
1444	{
1445	blk_tr = tr;
1446	blk_tracer_start(tr);
1447	return 0;
1448	}
1449
1450	static void blk_tracer_stop(struct trace_array *tr)
1451	{
1452	blk_tracer_enabled = false;
1453	}
1454
1455	static void blk_tracer_reset(struct trace_array *tr)
1456	{
1457	blk_tracer_stop(tr);
1458	}
1459
1460	static const struct {
1461	const char *act[2];
1462	void (*print)(struct trace_seq *s, const struct trace_entry *ent,
1463	bool has_cg);
1464	} what2act[] = {
1465	[__BLK_TA_QUEUE] = {{ "Q", "queue" }, blk_log_generic },
1466	[__BLK_TA_BACKMERGE] = {.act: { "M", "backmerge" }, .print: blk_log_generic },
1467	[__BLK_TA_FRONTMERGE] = {.act: { "F", "frontmerge" }, .print: blk_log_generic },
1468	[__BLK_TA_GETRQ] = {.act: { "G", "getrq" }, .print: blk_log_generic },
1469	[__BLK_TA_SLEEPRQ] = {.act: { "S", "sleeprq" }, .print: blk_log_generic },
1470	[__BLK_TA_REQUEUE] = {.act: { "R", "requeue" }, .print: blk_log_with_error },
1471	[__BLK_TA_ISSUE] = {.act: { "D", "issue" }, .print: blk_log_generic },
1472	[__BLK_TA_COMPLETE] = {.act: { "C", "complete" }, .print: blk_log_with_error },
1473	[__BLK_TA_PLUG] = {.act: { "P", "plug" }, .print: blk_log_plug },
1474	[__BLK_TA_UNPLUG_IO] = {.act: { "U", "unplug_io" }, .print: blk_log_unplug },
1475	[__BLK_TA_UNPLUG_TIMER] = {.act: { "UT", "unplug_timer" }, .print: blk_log_unplug },
1476	[__BLK_TA_INSERT] = {.act: { "I", "insert" }, .print: blk_log_generic },
1477	[__BLK_TA_SPLIT] = {.act: { "X", "split" }, .print: blk_log_split },
1478	[__BLK_TA_BOUNCE] = {.act: { "B", "bounce" }, .print: blk_log_generic },
1479	[__BLK_TA_REMAP] = {.act: { "A", "remap" }, .print: blk_log_remap },
1480	};
1481
1482	static enum print_line_t print_one_line(struct trace_iterator *iter,
1483	bool classic)
1484	{
1485	struct trace_array *tr = iter->tr;
1486	struct trace_seq *s = &iter->seq;
1487	const struct blk_io_trace *t;
1488	u16 what;
1489	bool long_act;
1490	blk_log_action_t *log_action;
1491	bool has_cg;
1492
1493	t = te_blk_io_trace(ent: iter->ent);
1494	what = (t->action & ((1 << BLK_TC_SHIFT) - 1)) & ~__BLK_TA_CGROUP;
1495	long_act = !!(tr->trace_flags & TRACE_ITER_VERBOSE);
1496	log_action = classic ? &blk_log_action_classic : &blk_log_action;
1497	has_cg = t->action & __BLK_TA_CGROUP;
1498
1499	if ((t->action & ~__BLK_TN_CGROUP) == BLK_TN_MESSAGE) {
1500	log_action(iter, long_act ? "message" : "m", has_cg);
1501	blk_log_msg(s, ent: iter->ent, has_cg);
1502	return trace_handle_return(s);
1503	}
1504
1505	if (unlikely(what == 0 || what >= ARRAY_SIZE(what2act)))
1506	trace_seq_printf(s, fmt: "Unknown action %x\n", what);
1507	else {
1508	log_action(iter, what2act[what].act[long_act], has_cg);
1509	what2act[what].print(s, iter->ent, has_cg);
1510	}
1511
1512	return trace_handle_return(s);
1513	}
1514
1515	static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
1516	int flags, struct trace_event *event)
1517	{
1518	return print_one_line(iter, classic: false);
1519	}
1520
1521	static void blk_trace_synthesize_old_trace(struct trace_iterator *iter)
1522	{
1523	struct trace_seq *s = &iter->seq;
1524	struct blk_io_trace *t = (struct blk_io_trace *)iter->ent;
1525	const int offset = offsetof(struct blk_io_trace, sector);
1526	struct blk_io_trace old = {
1527	.magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION,
1528	.time = iter->ts,
1529	};
1530
1531	trace_seq_putmem(s, mem: &old, len: offset);
1532	trace_seq_putmem(s, mem: &t->sector,
1533	len: sizeof(old) - offset + t->pdu_len);
1534	}
1535
1536	static enum print_line_t
1537	blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
1538	struct trace_event *event)
1539	{
1540	blk_trace_synthesize_old_trace(iter);
1541
1542	return trace_handle_return(s: &iter->seq);
1543	}
1544
1545	static enum print_line_t blk_tracer_print_line(struct trace_iterator *iter)
1546	{
1547	if ((iter->ent->type != TRACE_BLK) ||
1548	!(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC))
1549	return TRACE_TYPE_UNHANDLED;
1550
1551	return print_one_line(iter, classic: true);
1552	}
1553
1554	static int
1555	blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1556	{
1557	/* don't output context-info for blk_classic output */
1558	if (bit == TRACE_BLK_OPT_CLASSIC) {
1559	if (set)
1560	tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
1561	else
1562	tr->trace_flags |= TRACE_ITER_CONTEXT_INFO;
1563	}
1564	return 0;
1565	}
1566
1567	static struct tracer blk_tracer __read_mostly = {
1568	.name = "blk",
1569	.init = blk_tracer_init,
1570	.reset = blk_tracer_reset,
1571	.start = blk_tracer_start,
1572	.stop = blk_tracer_stop,
1573	.print_header = blk_tracer_print_header,
1574	.print_line = blk_tracer_print_line,
1575	.flags = &blk_tracer_flags,
1576	.set_flag = blk_tracer_set_flag,
1577	};
1578
1579	static struct trace_event_functions trace_blk_event_funcs = {
1580	.trace = blk_trace_event_print,
1581	.binary = blk_trace_event_print_binary,
1582	};
1583
1584	static struct trace_event trace_blk_event = {
1585	.type = TRACE_BLK,
1586	.funcs = &trace_blk_event_funcs,
1587	};
1588
1589	static int __init init_blk_tracer(void)
1590	{
1591	if (!register_trace_event(event: &trace_blk_event)) {
1592	pr_warn("Warning: could not register block events\n");
1593	return 1;
1594	}
1595
1596	if (register_tracer(type: &blk_tracer) != 0) {
1597	pr_warn("Warning: could not register the block tracer\n");
1598	unregister_trace_event(event: &trace_blk_event);
1599	return 1;
1600	}
1601
1602	return 0;
1603	}
1604
1605	device_initcall(init_blk_tracer);
1606
1607	static int blk_trace_remove_queue(struct request_queue *q)
1608	{
1609	struct blk_trace *bt;
1610
1611	bt = rcu_replace_pointer(q->blk_trace, NULL,
1612	lockdep_is_held(&q->debugfs_mutex));
1613	if (bt == NULL)
1614	return -EINVAL;
1615
1616	blk_trace_stop(bt);
1617
1618	put_probe_ref();
1619	synchronize_rcu();
1620	blk_trace_free(q, bt);
1621	return 0;
1622	}
1623
1624	/*
1625	* Setup everything required to start tracing
1626	*/
1627	static int blk_trace_setup_queue(struct request_queue *q,
1628	struct block_device *bdev)
1629	{
1630	struct blk_trace *bt = NULL;
1631	int ret = -ENOMEM;
1632
1633	bt = kzalloc(size: sizeof(*bt), GFP_KERNEL);
1634	if (!bt)
1635	return -ENOMEM;
1636
1637	bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, align: __alignof__(char));
1638	if (!bt->msg_data)
1639	goto free_bt;
1640
1641	bt->dev = bdev->bd_dev;
1642	bt->act_mask = (u16)-1;
1643
1644	blk_trace_setup_lba(bt, bdev);
1645
1646	rcu_assign_pointer(q->blk_trace, bt);
1647	get_probe_ref();
1648	return 0;
1649
1650	free_bt:
1651	blk_trace_free(q, bt);
1652	return ret;
1653	}
1654
1655	/*
1656	* sysfs interface to enable and configure tracing
1657	*/
1658
1659	static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1660	struct device_attribute *attr,
1661	char *buf);
1662	static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1663	struct device_attribute *attr,
1664	const char *buf, size_t count);
1665	#define BLK_TRACE_DEVICE_ATTR(_name) \
1666	DEVICE_ATTR(_name, S_IRUGO | S_IWUSR, \
1667	sysfs_blk_trace_attr_show, \
1668	sysfs_blk_trace_attr_store)
1669
1670	static BLK_TRACE_DEVICE_ATTR(enable);
1671	static BLK_TRACE_DEVICE_ATTR(act_mask);
1672	static BLK_TRACE_DEVICE_ATTR(pid);
1673	static BLK_TRACE_DEVICE_ATTR(start_lba);
1674	static BLK_TRACE_DEVICE_ATTR(end_lba);
1675
1676	static struct attribute *blk_trace_attrs[] = {
1677	&dev_attr_enable.attr,
1678	&dev_attr_act_mask.attr,
1679	&dev_attr_pid.attr,
1680	&dev_attr_start_lba.attr,
1681	&dev_attr_end_lba.attr,
1682	NULL
1683	};
1684
1685	struct attribute_group blk_trace_attr_group = {
1686	.name = "trace",
1687	.attrs = blk_trace_attrs,
1688	};
1689
1690	static const struct {
1691	int mask;
1692	const char *str;
1693	} mask_maps[] = {
1694	{ BLK_TC_READ, "read" },
1695	{ BLK_TC_WRITE, "write" },
1696	{ BLK_TC_FLUSH, "flush" },
1697	{ BLK_TC_SYNC, "sync" },
1698	{ BLK_TC_QUEUE, "queue" },
1699	{ BLK_TC_REQUEUE, "requeue" },
1700	{ BLK_TC_ISSUE, "issue" },
1701	{ BLK_TC_COMPLETE, "complete" },
1702	{ BLK_TC_FS, "fs" },
1703	{ BLK_TC_PC, "pc" },
1704	{ BLK_TC_NOTIFY, "notify" },
1705	{ BLK_TC_AHEAD, "ahead" },
1706	{ BLK_TC_META, "meta" },
1707	{ BLK_TC_DISCARD, "discard" },
1708	{ BLK_TC_DRV_DATA, "drv_data" },
1709	{ BLK_TC_FUA, "fua" },
1710	};
1711
1712	static int blk_trace_str2mask(const char *str)
1713	{
1714	int i;
1715	int mask = 0;
1716	char *buf, *s, *token;
1717
1718	buf = kstrdup(s: str, GFP_KERNEL);
1719	if (buf == NULL)
1720	return -ENOMEM;
1721	s = strstrip(str: buf);
1722
1723	while (1) {
1724	token = strsep(&s, ",");
1725	if (token == NULL)
1726	break;
1727
1728	if (*token == '\0')
1729	continue;
1730
1731	for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1732	if (strcasecmp(s1: token, s2: mask_maps[i].str) == 0) {
1733	mask |= mask_maps[i].mask;
1734	break;
1735	}
1736	}
1737	if (i == ARRAY_SIZE(mask_maps)) {
1738	mask = -EINVAL;
1739	break;
1740	}
1741	}
1742	kfree(objp: buf);
1743
1744	return mask;
1745	}
1746
1747	static ssize_t blk_trace_mask2str(char *buf, int mask)
1748	{
1749	int i;
1750	char *p = buf;
1751
1752	for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
1753	if (mask & mask_maps[i].mask) {
1754	p += sprintf(buf: p, fmt: "%s%s",
1755	(p == buf) ? "" : ",", mask_maps[i].str);
1756	}
1757	}
1758	*p++ = '\n';
1759
1760	return p - buf;
1761	}
1762
1763	static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
1764	struct device_attribute *attr,
1765	char *buf)
1766	{
1767	struct block_device *bdev = dev_to_bdev(dev);
1768	struct request_queue *q = bdev_get_queue(bdev);
1769	struct blk_trace *bt;
1770	ssize_t ret = -ENXIO;
1771
1772	mutex_lock(&q->debugfs_mutex);
1773
1774	bt = rcu_dereference_protected(q->blk_trace,
1775	lockdep_is_held(&q->debugfs_mutex));
1776	if (attr == &dev_attr_enable) {
1777	ret = sprintf(buf, fmt: "%u\n", !!bt);
1778	goto out_unlock_bdev;
1779	}
1780
1781	if (bt == NULL)
1782	ret = sprintf(buf, fmt: "disabled\n");
1783	else if (attr == &dev_attr_act_mask)
1784	ret = blk_trace_mask2str(buf, mask: bt->act_mask);
1785	else if (attr == &dev_attr_pid)
1786	ret = sprintf(buf, fmt: "%u\n", bt->pid);
1787	else if (attr == &dev_attr_start_lba)
1788	ret = sprintf(buf, fmt: "%llu\n", bt->start_lba);
1789	else if (attr == &dev_attr_end_lba)
1790	ret = sprintf(buf, fmt: "%llu\n", bt->end_lba);
1791
1792	out_unlock_bdev:
1793	mutex_unlock(lock: &q->debugfs_mutex);
1794	return ret;
1795	}
1796
1797	static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
1798	struct device_attribute *attr,
1799	const char *buf, size_t count)
1800	{
1801	struct block_device *bdev = dev_to_bdev(dev);
1802	struct request_queue *q = bdev_get_queue(bdev);
1803	struct blk_trace *bt;
1804	u64 value;
1805	ssize_t ret = -EINVAL;
1806
1807	if (count == 0)
1808	goto out;
1809
1810	if (attr == &dev_attr_act_mask) {
1811	if (kstrtoull(s: buf, base: 0, res: &value)) {
1812	/* Assume it is a list of trace category names */
1813	ret = blk_trace_str2mask(str: buf);
1814	if (ret < 0)
1815	goto out;
1816	value = ret;
1817	}
1818	} else {
1819	if (kstrtoull(s: buf, base: 0, res: &value))
1820	goto out;
1821	}
1822
1823	mutex_lock(&q->debugfs_mutex);
1824
1825	bt = rcu_dereference_protected(q->blk_trace,
1826	lockdep_is_held(&q->debugfs_mutex));
1827	if (attr == &dev_attr_enable) {
1828	if (!!value == !!bt) {
1829	ret = 0;
1830	goto out_unlock_bdev;
1831	}
1832	if (value)
1833	ret = blk_trace_setup_queue(q, bdev);
1834	else
1835	ret = blk_trace_remove_queue(q);
1836	goto out_unlock_bdev;
1837	}
1838
1839	ret = 0;
1840	if (bt == NULL) {
1841	ret = blk_trace_setup_queue(q, bdev);
1842	bt = rcu_dereference_protected(q->blk_trace,
1843	lockdep_is_held(&q->debugfs_mutex));
1844	}
1845
1846	if (ret == 0) {
1847	if (attr == &dev_attr_act_mask)
1848	bt->act_mask = value;
1849	else if (attr == &dev_attr_pid)
1850	bt->pid = value;
1851	else if (attr == &dev_attr_start_lba)
1852	bt->start_lba = value;
1853	else if (attr == &dev_attr_end_lba)
1854	bt->end_lba = value;
1855	}
1856
1857	out_unlock_bdev:
1858	mutex_unlock(lock: &q->debugfs_mutex);
1859	out:
1860	return ret ? ret : count;
1861	}
1862	#endif /* CONFIG_BLK_DEV_IO_TRACE */
1863
1864	#ifdef CONFIG_EVENT_TRACING
1865
1866	/**
1867	* blk_fill_rwbs - Fill the buffer rwbs by mapping op to character string.
1868	* @rwbs: buffer to be filled
1869	* @opf: request operation type (REQ_OP_XXX) and flags for the tracepoint
1870	*
1871	* Description:
1872	* Maps each request operation and flag to a single character and fills the
1873	* buffer provided by the caller with resulting string.
1874	*
1875	**/
1876	void blk_fill_rwbs(char *rwbs, blk_opf_t opf)
1877	{
1878	int i = 0;
1879
1880	if (opf & REQ_PREFLUSH)
1881	rwbs[i++] = 'F';
1882
1883	switch (opf & REQ_OP_MASK) {
1884	case REQ_OP_WRITE:
1885	rwbs[i++] = 'W';
1886	break;
1887	case REQ_OP_DISCARD:
1888	rwbs[i++] = 'D';
1889	break;
1890	case REQ_OP_SECURE_ERASE:
1891	rwbs[i++] = 'D';
1892	rwbs[i++] = 'E';
1893	break;
1894	case REQ_OP_FLUSH:
1895	rwbs[i++] = 'F';
1896	break;
1897	case REQ_OP_READ:
1898	rwbs[i++] = 'R';
1899	break;
1900	default:
1901	rwbs[i++] = 'N';
1902	}
1903
1904	if (opf & REQ_FUA)
1905	rwbs[i++] = 'F';
1906	if (opf & REQ_RAHEAD)
1907	rwbs[i++] = 'A';
1908	if (opf & REQ_SYNC)
1909	rwbs[i++] = 'S';
1910	if (opf & REQ_META)
1911	rwbs[i++] = 'M';
1912
1913	rwbs[i] = '\0';
1914	}
1915	EXPORT_SYMBOL_GPL(blk_fill_rwbs);
1916
1917	#endif /* CONFIG_EVENT_TRACING */
1918
1919