blob: d3679dd1d2201785e91194415d01736a16af54bc [file] [log] [blame]
Jens Axboe2056a782006-03-23 20:00:26 +01001/*
Jens Axboe0fe23472006-09-04 15:41:16 +02002 * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
Jens Axboe2056a782006-03-23 20:00:26 +01003 *
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 */
Jens Axboe2056a782006-03-23 20:00:26 +010018#include <linux/kernel.h>
19#include <linux/blkdev.h>
20#include <linux/blktrace_api.h>
21#include <linux/percpu.h>
22#include <linux/init.h>
23#include <linux/mutex.h>
24#include <linux/debugfs.h>
Olaf Kirchbe1c6342006-12-01 10:39:12 +010025#include <linux/time.h>
Jens Axboe2056a782006-03-23 20:00:26 +010026#include <asm/uaccess.h>
27
28static DEFINE_PER_CPU(unsigned long long, blk_trace_cpu_offset) = { 0, };
29static unsigned int blktrace_seq __read_mostly = 1;
30
31/*
Olaf Kirchbe1c6342006-12-01 10:39:12 +010032 * Send out a notify message.
33 */
Jens Axboea8630552006-12-04 09:30:58 +010034static void trace_note(struct blk_trace *bt, pid_t pid, int action,
35 const void *data, size_t len)
Olaf Kirchbe1c6342006-12-01 10:39:12 +010036{
37 struct blk_io_trace *t;
Olaf Kirchbe1c6342006-12-01 10:39:12 +010038
39 t = relay_reserve(bt->rchan, sizeof(*t) + len);
Jens Axboed3d9d2a2006-12-04 09:27:41 +010040 if (t) {
41 const int cpu = smp_processor_id();
Olaf Kirchbe1c6342006-12-01 10:39:12 +010042
Jens Axboed3d9d2a2006-12-04 09:27:41 +010043 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
44 t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu);
45 t->device = bt->dev;
46 t->action = action;
47 t->pid = pid;
48 t->cpu = cpu;
49 t->pdu_len = len;
50 memcpy((void *) t + sizeof(*t), data, len);
51 }
Olaf Kirchbe1c6342006-12-01 10:39:12 +010052}
53
54/*
Jens Axboe2056a782006-03-23 20:00:26 +010055 * Send out a notify for this process, if we haven't done so since a trace
56 * started
57 */
58static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
59{
Jens Axboea8630552006-12-04 09:30:58 +010060 tsk->btrace_seq = blktrace_seq;
61 trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm));
Olaf Kirchbe1c6342006-12-01 10:39:12 +010062}
Jens Axboe2056a782006-03-23 20:00:26 +010063
Olaf Kirchbe1c6342006-12-01 10:39:12 +010064static void trace_note_time(struct blk_trace *bt)
65{
66 struct timespec now;
67 unsigned long flags;
68 u32 words[2];
69
70 getnstimeofday(&now);
71 words[0] = now.tv_sec;
72 words[1] = now.tv_nsec;
73
74 local_irq_save(flags);
75 trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
76 local_irq_restore(flags);
Jens Axboe2056a782006-03-23 20:00:26 +010077}
78
79static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
80 pid_t pid)
81{
82 if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
83 return 1;
84 if (sector < bt->start_lba || sector > bt->end_lba)
85 return 1;
86 if (bt->pid && pid != bt->pid)
87 return 1;
88
89 return 0;
90}
91
92/*
93 * Data direction bit lookup
94 */
95static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ), BLK_TC_ACT(BLK_TC_WRITE) };
96
97/*
98 * Bio action bits of interest
99 */
Jens Axboe7457e6e2006-07-23 02:12:01 +0200100static u32 bio_act[9] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC), 0, BLK_TC_ACT(BLK_TC_AHEAD), 0, 0, 0, BLK_TC_ACT(BLK_TC_META) };
Jens Axboe2056a782006-03-23 20:00:26 +0100101
102/*
103 * More could be added as needed, taking care to increment the decrementer
104 * to get correct indexing
105 */
106#define trace_barrier_bit(rw) \
107 (((rw) & (1 << BIO_RW_BARRIER)) >> (BIO_RW_BARRIER - 0))
108#define trace_sync_bit(rw) \
109 (((rw) & (1 << BIO_RW_SYNC)) >> (BIO_RW_SYNC - 1))
Nathan Scott40359cc2006-07-06 10:03:28 +0200110#define trace_ahead_bit(rw) \
Milton Millerad01b1c2006-07-25 15:04:13 +0200111 (((rw) & (1 << BIO_RW_AHEAD)) << (2 - BIO_RW_AHEAD))
Jens Axboe7457e6e2006-07-23 02:12:01 +0200112#define trace_meta_bit(rw) \
113 (((rw) & (1 << BIO_RW_META)) >> (BIO_RW_META - 3))
Jens Axboe2056a782006-03-23 20:00:26 +0100114
115/*
116 * The worker for the various blk_add_trace*() types. Fills out a
117 * blk_io_trace structure and places it in a per-cpu subbuffer.
118 */
119void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
120 int rw, u32 what, int error, int pdu_len, void *pdu_data)
121{
122 struct task_struct *tsk = current;
123 struct blk_io_trace *t;
124 unsigned long flags;
125 unsigned long *sequence;
126 pid_t pid;
127 int cpu;
128
129 if (unlikely(bt->trace_state != Blktrace_running))
130 return;
131
132 what |= ddir_act[rw & WRITE];
133 what |= bio_act[trace_barrier_bit(rw)];
134 what |= bio_act[trace_sync_bit(rw)];
Nathan Scott40359cc2006-07-06 10:03:28 +0200135 what |= bio_act[trace_ahead_bit(rw)];
Jens Axboe7457e6e2006-07-23 02:12:01 +0200136 what |= bio_act[trace_meta_bit(rw)];
Jens Axboe2056a782006-03-23 20:00:26 +0100137
138 pid = tsk->pid;
139 if (unlikely(act_log_check(bt, what, sector, pid)))
140 return;
141
142 /*
143 * A word about the locking here - we disable interrupts to reserve
144 * some space in the relay per-cpu buffer, to prevent an irq
145 * from coming in and stepping on our toes. Once reserved, it's
146 * enough to get preemption disabled to prevent read of this data
147 * before we are through filling it. get_cpu()/put_cpu() does this
148 * for us
149 */
150 local_irq_save(flags);
151
152 if (unlikely(tsk->btrace_seq != blktrace_seq))
153 trace_note_tsk(bt, tsk);
154
155 t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
156 if (t) {
157 cpu = smp_processor_id();
158 sequence = per_cpu_ptr(bt->sequence, cpu);
159
160 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
161 t->sequence = ++(*sequence);
162 t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu);
163 t->sector = sector;
164 t->bytes = bytes;
165 t->action = what;
166 t->pid = pid;
167 t->device = bt->dev;
168 t->cpu = cpu;
169 t->error = error;
170 t->pdu_len = pdu_len;
171
172 if (pdu_len)
173 memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
174 }
175
176 local_irq_restore(flags);
177}
178
179EXPORT_SYMBOL_GPL(__blk_add_trace);
180
181static struct dentry *blk_tree_root;
182static struct mutex blk_tree_mutex;
183static unsigned int root_users;
184
185static inline void blk_remove_root(void)
186{
187 if (blk_tree_root) {
188 debugfs_remove(blk_tree_root);
189 blk_tree_root = NULL;
190 }
191}
192
193static void blk_remove_tree(struct dentry *dir)
194{
195 mutex_lock(&blk_tree_mutex);
196 debugfs_remove(dir);
197 if (--root_users == 0)
198 blk_remove_root();
199 mutex_unlock(&blk_tree_mutex);
200}
201
202static struct dentry *blk_create_tree(const char *blk_name)
203{
204 struct dentry *dir = NULL;
205
206 mutex_lock(&blk_tree_mutex);
207
208 if (!blk_tree_root) {
209 blk_tree_root = debugfs_create_dir("block", NULL);
210 if (!blk_tree_root)
211 goto err;
212 }
213
214 dir = debugfs_create_dir(blk_name, blk_tree_root);
215 if (dir)
216 root_users++;
217 else
218 blk_remove_root();
219
220err:
221 mutex_unlock(&blk_tree_mutex);
222 return dir;
223}
224
225static void blk_trace_cleanup(struct blk_trace *bt)
226{
227 relay_close(bt->rchan);
228 debugfs_remove(bt->dropped_file);
229 blk_remove_tree(bt->dir);
230 free_percpu(bt->sequence);
231 kfree(bt);
232}
233
234static int blk_trace_remove(request_queue_t *q)
235{
236 struct blk_trace *bt;
237
238 bt = xchg(&q->blk_trace, NULL);
239 if (!bt)
240 return -EINVAL;
241
242 if (bt->trace_state == Blktrace_setup ||
243 bt->trace_state == Blktrace_stopped)
244 blk_trace_cleanup(bt);
245
246 return 0;
247}
248
249static int blk_dropped_open(struct inode *inode, struct file *filp)
250{
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700251 filp->private_data = inode->i_private;
Jens Axboe2056a782006-03-23 20:00:26 +0100252
253 return 0;
254}
255
256static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
257 size_t count, loff_t *ppos)
258{
259 struct blk_trace *bt = filp->private_data;
260 char buf[16];
261
262 snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
263
264 return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
265}
266
267static struct file_operations blk_dropped_fops = {
268 .owner = THIS_MODULE,
269 .open = blk_dropped_open,
270 .read = blk_dropped_read,
271};
272
273/*
274 * Keep track of how many times we encountered a full subbuffer, to aid
275 * the user space app in telling how many lost events there were.
276 */
277static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
278 void *prev_subbuf, size_t prev_padding)
279{
280 struct blk_trace *bt;
281
282 if (!relay_buf_full(buf))
283 return 1;
284
285 bt = buf->chan->private_data;
286 atomic_inc(&bt->dropped);
287 return 0;
288}
289
290static int blk_remove_buf_file_callback(struct dentry *dentry)
291{
292 debugfs_remove(dentry);
293 return 0;
294}
295
296static struct dentry *blk_create_buf_file_callback(const char *filename,
297 struct dentry *parent,
298 int mode,
299 struct rchan_buf *buf,
300 int *is_global)
301{
302 return debugfs_create_file(filename, mode, parent, buf,
303 &relay_file_operations);
304}
305
306static struct rchan_callbacks blk_relay_callbacks = {
307 .subbuf_start = blk_subbuf_start_callback,
308 .create_buf_file = blk_create_buf_file_callback,
309 .remove_buf_file = blk_remove_buf_file_callback,
310};
311
312/*
313 * Setup everything required to start tracing
314 */
315static int blk_trace_setup(request_queue_t *q, struct block_device *bdev,
316 char __user *arg)
317{
318 struct blk_user_trace_setup buts;
319 struct blk_trace *old_bt, *bt = NULL;
320 struct dentry *dir = NULL;
321 char b[BDEVNAME_SIZE];
322 int ret, i;
323
324 if (copy_from_user(&buts, arg, sizeof(buts)))
325 return -EFAULT;
326
327 if (!buts.buf_size || !buts.buf_nr)
328 return -EINVAL;
329
330 strcpy(buts.name, bdevname(bdev, b));
331
332 /*
333 * some device names have larger paths - convert the slashes
334 * to underscores for this to work as expected
335 */
336 for (i = 0; i < strlen(buts.name); i++)
337 if (buts.name[i] == '/')
338 buts.name[i] = '_';
339
340 if (copy_to_user(arg, &buts, sizeof(buts)))
341 return -EFAULT;
342
343 ret = -ENOMEM;
344 bt = kzalloc(sizeof(*bt), GFP_KERNEL);
345 if (!bt)
346 goto err;
347
348 bt->sequence = alloc_percpu(unsigned long);
349 if (!bt->sequence)
350 goto err;
351
352 ret = -ENOENT;
353 dir = blk_create_tree(buts.name);
354 if (!dir)
355 goto err;
356
357 bt->dir = dir;
358 bt->dev = bdev->bd_dev;
359 atomic_set(&bt->dropped, 0);
360
361 ret = -EIO;
362 bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops);
363 if (!bt->dropped_file)
364 goto err;
365
366 bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, &blk_relay_callbacks);
367 if (!bt->rchan)
368 goto err;
369 bt->rchan->private_data = bt;
370
371 bt->act_mask = buts.act_mask;
372 if (!bt->act_mask)
373 bt->act_mask = (u16) -1;
374
375 bt->start_lba = buts.start_lba;
376 bt->end_lba = buts.end_lba;
377 if (!bt->end_lba)
378 bt->end_lba = -1ULL;
379
380 bt->pid = buts.pid;
381 bt->trace_state = Blktrace_setup;
382
383 ret = -EBUSY;
384 old_bt = xchg(&q->blk_trace, bt);
385 if (old_bt) {
386 (void) xchg(&q->blk_trace, old_bt);
387 goto err;
388 }
389
390 return 0;
391err:
392 if (dir)
393 blk_remove_tree(dir);
394 if (bt) {
395 if (bt->dropped_file)
396 debugfs_remove(bt->dropped_file);
Alan Sterna1205862006-12-06 20:32:37 -0800397 free_percpu(bt->sequence);
Jens Axboe2056a782006-03-23 20:00:26 +0100398 if (bt->rchan)
399 relay_close(bt->rchan);
400 kfree(bt);
401 }
402 return ret;
403}
404
405static int blk_trace_startstop(request_queue_t *q, int start)
406{
407 struct blk_trace *bt;
408 int ret;
409
410 if ((bt = q->blk_trace) == NULL)
411 return -EINVAL;
412
413 /*
414 * For starting a trace, we can transition from a setup or stopped
415 * trace. For stopping a trace, the state must be running
416 */
417 ret = -EINVAL;
418 if (start) {
419 if (bt->trace_state == Blktrace_setup ||
420 bt->trace_state == Blktrace_stopped) {
421 blktrace_seq++;
422 smp_mb();
423 bt->trace_state = Blktrace_running;
Olaf Kirchbe1c6342006-12-01 10:39:12 +0100424
425 trace_note_time(bt);
Jens Axboe2056a782006-03-23 20:00:26 +0100426 ret = 0;
427 }
428 } else {
429 if (bt->trace_state == Blktrace_running) {
430 bt->trace_state = Blktrace_stopped;
431 relay_flush(bt->rchan);
432 ret = 0;
433 }
434 }
435
436 return ret;
437}
438
439/**
440 * blk_trace_ioctl: - handle the ioctls associated with tracing
441 * @bdev: the block device
442 * @cmd: the ioctl cmd
443 * @arg: the argument data, if any
444 *
445 **/
446int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
447{
448 request_queue_t *q;
449 int ret, start = 0;
450
451 q = bdev_get_queue(bdev);
452 if (!q)
453 return -ENXIO;
454
455 mutex_lock(&bdev->bd_mutex);
456
457 switch (cmd) {
458 case BLKTRACESETUP:
459 ret = blk_trace_setup(q, bdev, arg);
460 break;
461 case BLKTRACESTART:
462 start = 1;
463 case BLKTRACESTOP:
464 ret = blk_trace_startstop(q, start);
465 break;
466 case BLKTRACETEARDOWN:
467 ret = blk_trace_remove(q);
468 break;
469 default:
470 ret = -ENOTTY;
471 break;
472 }
473
474 mutex_unlock(&bdev->bd_mutex);
475 return ret;
476}
477
478/**
479 * blk_trace_shutdown: - stop and cleanup trace structures
480 * @q: the request queue associated with the device
481 *
482 **/
483void blk_trace_shutdown(request_queue_t *q)
484{
Alexey Dobriyan6c5c9342006-09-29 01:59:40 -0700485 if (q->blk_trace) {
486 blk_trace_startstop(q, 0);
487 blk_trace_remove(q);
488 }
Jens Axboe2056a782006-03-23 20:00:26 +0100489}
490
491/*
492 * Average offset over two calls to sched_clock() with a gettimeofday()
493 * in the middle
494 */
495static void blk_check_time(unsigned long long *t)
496{
497 unsigned long long a, b;
498 struct timeval tv;
499
500 a = sched_clock();
501 do_gettimeofday(&tv);
502 b = sched_clock();
503
504 *t = tv.tv_sec * 1000000000 + tv.tv_usec * 1000;
505 *t -= (a + b) / 2;
506}
507
Martin Peschke40909592006-08-29 19:52:55 +0200508/*
509 * calibrate our inter-CPU timings
510 */
Jens Axboe2056a782006-03-23 20:00:26 +0100511static void blk_trace_check_cpu_time(void *data)
512{
513 unsigned long long *t;
514 int cpu = get_cpu();
515
516 t = &per_cpu(blk_trace_cpu_offset, cpu);
517
518 /*
519 * Just call it twice, hopefully the second call will be cache hot
520 * and a little more precise
521 */
522 blk_check_time(t);
523 blk_check_time(t);
524
525 put_cpu();
526}
527
Jens Axboe2056a782006-03-23 20:00:26 +0100528static void blk_trace_set_ht_offsets(void)
529{
530#if defined(CONFIG_SCHED_SMT)
531 int cpu, i;
532
533 /*
534 * now make sure HT siblings have the same time offset
535 */
536 preempt_disable();
537 for_each_online_cpu(cpu) {
538 unsigned long long *cpu_off, *sibling_off;
539
540 for_each_cpu_mask(i, cpu_sibling_map[cpu]) {
541 if (i == cpu)
542 continue;
543
544 cpu_off = &per_cpu(blk_trace_cpu_offset, cpu);
545 sibling_off = &per_cpu(blk_trace_cpu_offset, i);
546 *sibling_off = *cpu_off;
547 }
548 }
549 preempt_enable();
550#endif
551}
552
553static __init int blk_trace_init(void)
554{
555 mutex_init(&blk_tree_mutex);
Martin Peschke40909592006-08-29 19:52:55 +0200556 on_each_cpu(blk_trace_check_cpu_time, NULL, 1, 1);
Jens Axboe2056a782006-03-23 20:00:26 +0100557 blk_trace_set_ht_offsets();
558
559 return 0;
560}
561
562module_init(blk_trace_init);
563