Root/kernel/trace/blktrace.c

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

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