Commit | Line | Data |
---|---|---|
2056a782 | 1 | /* |
0fe23479 | 2 | * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk> |
2056a782 JA |
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 | */ | |
2056a782 JA |
18 | #include <linux/kernel.h> |
19 | #include <linux/blkdev.h> | |
20 | #include <linux/blktrace_api.h> | |
21 | #include <linux/percpu.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/mutex.h> | |
24 | #include <linux/debugfs.h> | |
25 | #include <asm/uaccess.h> | |
26 | ||
27 | static DEFINE_PER_CPU(unsigned long long, blk_trace_cpu_offset) = { 0, }; | |
28 | static unsigned int blktrace_seq __read_mostly = 1; | |
29 | ||
30 | /* | |
31 | * Send out a notify for this process, if we haven't done so since a trace | |
32 | * started | |
33 | */ | |
34 | static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk) | |
35 | { | |
36 | struct blk_io_trace *t; | |
37 | ||
38 | t = relay_reserve(bt->rchan, sizeof(*t) + sizeof(tsk->comm)); | |
39 | if (t) { | |
40 | t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; | |
41 | t->device = bt->dev; | |
42 | t->action = BLK_TC_ACT(BLK_TC_NOTIFY); | |
43 | t->pid = tsk->pid; | |
44 | t->cpu = smp_processor_id(); | |
45 | t->pdu_len = sizeof(tsk->comm); | |
46 | memcpy((void *) t + sizeof(*t), tsk->comm, t->pdu_len); | |
47 | tsk->btrace_seq = blktrace_seq; | |
48 | } | |
49 | } | |
50 | ||
51 | static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector, | |
52 | pid_t pid) | |
53 | { | |
54 | if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0) | |
55 | return 1; | |
56 | if (sector < bt->start_lba || sector > bt->end_lba) | |
57 | return 1; | |
58 | if (bt->pid && pid != bt->pid) | |
59 | return 1; | |
60 | ||
61 | return 0; | |
62 | } | |
63 | ||
64 | /* | |
65 | * Data direction bit lookup | |
66 | */ | |
67 | static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ), BLK_TC_ACT(BLK_TC_WRITE) }; | |
68 | ||
69 | /* | |
70 | * Bio action bits of interest | |
71 | */ | |
7457e6e2 | 72 | static 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) }; |
2056a782 JA |
73 | |
74 | /* | |
75 | * More could be added as needed, taking care to increment the decrementer | |
76 | * to get correct indexing | |
77 | */ | |
78 | #define trace_barrier_bit(rw) \ | |
79 | (((rw) & (1 << BIO_RW_BARRIER)) >> (BIO_RW_BARRIER - 0)) | |
80 | #define trace_sync_bit(rw) \ | |
81 | (((rw) & (1 << BIO_RW_SYNC)) >> (BIO_RW_SYNC - 1)) | |
40359ccb | 82 | #define trace_ahead_bit(rw) \ |
ad01b1ca | 83 | (((rw) & (1 << BIO_RW_AHEAD)) << (2 - BIO_RW_AHEAD)) |
7457e6e2 JA |
84 | #define trace_meta_bit(rw) \ |
85 | (((rw) & (1 << BIO_RW_META)) >> (BIO_RW_META - 3)) | |
2056a782 JA |
86 | |
87 | /* | |
88 | * The worker for the various blk_add_trace*() types. Fills out a | |
89 | * blk_io_trace structure and places it in a per-cpu subbuffer. | |
90 | */ | |
91 | void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, | |
92 | int rw, u32 what, int error, int pdu_len, void *pdu_data) | |
93 | { | |
94 | struct task_struct *tsk = current; | |
95 | struct blk_io_trace *t; | |
96 | unsigned long flags; | |
97 | unsigned long *sequence; | |
98 | pid_t pid; | |
99 | int cpu; | |
100 | ||
101 | if (unlikely(bt->trace_state != Blktrace_running)) | |
102 | return; | |
103 | ||
104 | what |= ddir_act[rw & WRITE]; | |
105 | what |= bio_act[trace_barrier_bit(rw)]; | |
106 | what |= bio_act[trace_sync_bit(rw)]; | |
40359ccb | 107 | what |= bio_act[trace_ahead_bit(rw)]; |
7457e6e2 | 108 | what |= bio_act[trace_meta_bit(rw)]; |
2056a782 JA |
109 | |
110 | pid = tsk->pid; | |
111 | if (unlikely(act_log_check(bt, what, sector, pid))) | |
112 | return; | |
113 | ||
114 | /* | |
115 | * A word about the locking here - we disable interrupts to reserve | |
116 | * some space in the relay per-cpu buffer, to prevent an irq | |
117 | * from coming in and stepping on our toes. Once reserved, it's | |
118 | * enough to get preemption disabled to prevent read of this data | |
119 | * before we are through filling it. get_cpu()/put_cpu() does this | |
120 | * for us | |
121 | */ | |
122 | local_irq_save(flags); | |
123 | ||
124 | if (unlikely(tsk->btrace_seq != blktrace_seq)) | |
125 | trace_note_tsk(bt, tsk); | |
126 | ||
127 | t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len); | |
128 | if (t) { | |
129 | cpu = smp_processor_id(); | |
130 | sequence = per_cpu_ptr(bt->sequence, cpu); | |
131 | ||
132 | t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; | |
133 | t->sequence = ++(*sequence); | |
134 | t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu); | |
135 | t->sector = sector; | |
136 | t->bytes = bytes; | |
137 | t->action = what; | |
138 | t->pid = pid; | |
139 | t->device = bt->dev; | |
140 | t->cpu = cpu; | |
141 | t->error = error; | |
142 | t->pdu_len = pdu_len; | |
143 | ||
144 | if (pdu_len) | |
145 | memcpy((void *) t + sizeof(*t), pdu_data, pdu_len); | |
146 | } | |
147 | ||
148 | local_irq_restore(flags); | |
149 | } | |
150 | ||
151 | EXPORT_SYMBOL_GPL(__blk_add_trace); | |
152 | ||
153 | static struct dentry *blk_tree_root; | |
154 | static struct mutex blk_tree_mutex; | |
155 | static unsigned int root_users; | |
156 | ||
157 | static inline void blk_remove_root(void) | |
158 | { | |
159 | if (blk_tree_root) { | |
160 | debugfs_remove(blk_tree_root); | |
161 | blk_tree_root = NULL; | |
162 | } | |
163 | } | |
164 | ||
165 | static void blk_remove_tree(struct dentry *dir) | |
166 | { | |
167 | mutex_lock(&blk_tree_mutex); | |
168 | debugfs_remove(dir); | |
169 | if (--root_users == 0) | |
170 | blk_remove_root(); | |
171 | mutex_unlock(&blk_tree_mutex); | |
172 | } | |
173 | ||
174 | static struct dentry *blk_create_tree(const char *blk_name) | |
175 | { | |
176 | struct dentry *dir = NULL; | |
177 | ||
178 | mutex_lock(&blk_tree_mutex); | |
179 | ||
180 | if (!blk_tree_root) { | |
181 | blk_tree_root = debugfs_create_dir("block", NULL); | |
182 | if (!blk_tree_root) | |
183 | goto err; | |
184 | } | |
185 | ||
186 | dir = debugfs_create_dir(blk_name, blk_tree_root); | |
187 | if (dir) | |
188 | root_users++; | |
189 | else | |
190 | blk_remove_root(); | |
191 | ||
192 | err: | |
193 | mutex_unlock(&blk_tree_mutex); | |
194 | return dir; | |
195 | } | |
196 | ||
197 | static void blk_trace_cleanup(struct blk_trace *bt) | |
198 | { | |
199 | relay_close(bt->rchan); | |
200 | debugfs_remove(bt->dropped_file); | |
201 | blk_remove_tree(bt->dir); | |
202 | free_percpu(bt->sequence); | |
203 | kfree(bt); | |
204 | } | |
205 | ||
206 | static int blk_trace_remove(request_queue_t *q) | |
207 | { | |
208 | struct blk_trace *bt; | |
209 | ||
210 | bt = xchg(&q->blk_trace, NULL); | |
211 | if (!bt) | |
212 | return -EINVAL; | |
213 | ||
214 | if (bt->trace_state == Blktrace_setup || | |
215 | bt->trace_state == Blktrace_stopped) | |
216 | blk_trace_cleanup(bt); | |
217 | ||
218 | return 0; | |
219 | } | |
220 | ||
221 | static int blk_dropped_open(struct inode *inode, struct file *filp) | |
222 | { | |
8e18e294 | 223 | filp->private_data = inode->i_private; |
2056a782 JA |
224 | |
225 | return 0; | |
226 | } | |
227 | ||
228 | static ssize_t blk_dropped_read(struct file *filp, char __user *buffer, | |
229 | size_t count, loff_t *ppos) | |
230 | { | |
231 | struct blk_trace *bt = filp->private_data; | |
232 | char buf[16]; | |
233 | ||
234 | snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped)); | |
235 | ||
236 | return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf)); | |
237 | } | |
238 | ||
239 | static struct file_operations blk_dropped_fops = { | |
240 | .owner = THIS_MODULE, | |
241 | .open = blk_dropped_open, | |
242 | .read = blk_dropped_read, | |
243 | }; | |
244 | ||
245 | /* | |
246 | * Keep track of how many times we encountered a full subbuffer, to aid | |
247 | * the user space app in telling how many lost events there were. | |
248 | */ | |
249 | static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf, | |
250 | void *prev_subbuf, size_t prev_padding) | |
251 | { | |
252 | struct blk_trace *bt; | |
253 | ||
254 | if (!relay_buf_full(buf)) | |
255 | return 1; | |
256 | ||
257 | bt = buf->chan->private_data; | |
258 | atomic_inc(&bt->dropped); | |
259 | return 0; | |
260 | } | |
261 | ||
262 | static int blk_remove_buf_file_callback(struct dentry *dentry) | |
263 | { | |
264 | debugfs_remove(dentry); | |
265 | return 0; | |
266 | } | |
267 | ||
268 | static struct dentry *blk_create_buf_file_callback(const char *filename, | |
269 | struct dentry *parent, | |
270 | int mode, | |
271 | struct rchan_buf *buf, | |
272 | int *is_global) | |
273 | { | |
274 | return debugfs_create_file(filename, mode, parent, buf, | |
275 | &relay_file_operations); | |
276 | } | |
277 | ||
278 | static struct rchan_callbacks blk_relay_callbacks = { | |
279 | .subbuf_start = blk_subbuf_start_callback, | |
280 | .create_buf_file = blk_create_buf_file_callback, | |
281 | .remove_buf_file = blk_remove_buf_file_callback, | |
282 | }; | |
283 | ||
284 | /* | |
285 | * Setup everything required to start tracing | |
286 | */ | |
287 | static int blk_trace_setup(request_queue_t *q, struct block_device *bdev, | |
288 | char __user *arg) | |
289 | { | |
290 | struct blk_user_trace_setup buts; | |
291 | struct blk_trace *old_bt, *bt = NULL; | |
292 | struct dentry *dir = NULL; | |
293 | char b[BDEVNAME_SIZE]; | |
294 | int ret, i; | |
295 | ||
296 | if (copy_from_user(&buts, arg, sizeof(buts))) | |
297 | return -EFAULT; | |
298 | ||
299 | if (!buts.buf_size || !buts.buf_nr) | |
300 | return -EINVAL; | |
301 | ||
302 | strcpy(buts.name, bdevname(bdev, b)); | |
303 | ||
304 | /* | |
305 | * some device names have larger paths - convert the slashes | |
306 | * to underscores for this to work as expected | |
307 | */ | |
308 | for (i = 0; i < strlen(buts.name); i++) | |
309 | if (buts.name[i] == '/') | |
310 | buts.name[i] = '_'; | |
311 | ||
312 | if (copy_to_user(arg, &buts, sizeof(buts))) | |
313 | return -EFAULT; | |
314 | ||
315 | ret = -ENOMEM; | |
316 | bt = kzalloc(sizeof(*bt), GFP_KERNEL); | |
317 | if (!bt) | |
318 | goto err; | |
319 | ||
320 | bt->sequence = alloc_percpu(unsigned long); | |
321 | if (!bt->sequence) | |
322 | goto err; | |
323 | ||
324 | ret = -ENOENT; | |
325 | dir = blk_create_tree(buts.name); | |
326 | if (!dir) | |
327 | goto err; | |
328 | ||
329 | bt->dir = dir; | |
330 | bt->dev = bdev->bd_dev; | |
331 | atomic_set(&bt->dropped, 0); | |
332 | ||
333 | ret = -EIO; | |
334 | bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops); | |
335 | if (!bt->dropped_file) | |
336 | goto err; | |
337 | ||
338 | bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, &blk_relay_callbacks); | |
339 | if (!bt->rchan) | |
340 | goto err; | |
341 | bt->rchan->private_data = bt; | |
342 | ||
343 | bt->act_mask = buts.act_mask; | |
344 | if (!bt->act_mask) | |
345 | bt->act_mask = (u16) -1; | |
346 | ||
347 | bt->start_lba = buts.start_lba; | |
348 | bt->end_lba = buts.end_lba; | |
349 | if (!bt->end_lba) | |
350 | bt->end_lba = -1ULL; | |
351 | ||
352 | bt->pid = buts.pid; | |
353 | bt->trace_state = Blktrace_setup; | |
354 | ||
355 | ret = -EBUSY; | |
356 | old_bt = xchg(&q->blk_trace, bt); | |
357 | if (old_bt) { | |
358 | (void) xchg(&q->blk_trace, old_bt); | |
359 | goto err; | |
360 | } | |
361 | ||
362 | return 0; | |
363 | err: | |
364 | if (dir) | |
365 | blk_remove_tree(dir); | |
366 | if (bt) { | |
367 | if (bt->dropped_file) | |
368 | debugfs_remove(bt->dropped_file); | |
369 | if (bt->sequence) | |
370 | free_percpu(bt->sequence); | |
371 | if (bt->rchan) | |
372 | relay_close(bt->rchan); | |
373 | kfree(bt); | |
374 | } | |
375 | return ret; | |
376 | } | |
377 | ||
378 | static int blk_trace_startstop(request_queue_t *q, int start) | |
379 | { | |
380 | struct blk_trace *bt; | |
381 | int ret; | |
382 | ||
383 | if ((bt = q->blk_trace) == NULL) | |
384 | return -EINVAL; | |
385 | ||
386 | /* | |
387 | * For starting a trace, we can transition from a setup or stopped | |
388 | * trace. For stopping a trace, the state must be running | |
389 | */ | |
390 | ret = -EINVAL; | |
391 | if (start) { | |
392 | if (bt->trace_state == Blktrace_setup || | |
393 | bt->trace_state == Blktrace_stopped) { | |
394 | blktrace_seq++; | |
395 | smp_mb(); | |
396 | bt->trace_state = Blktrace_running; | |
397 | ret = 0; | |
398 | } | |
399 | } else { | |
400 | if (bt->trace_state == Blktrace_running) { | |
401 | bt->trace_state = Blktrace_stopped; | |
402 | relay_flush(bt->rchan); | |
403 | ret = 0; | |
404 | } | |
405 | } | |
406 | ||
407 | return ret; | |
408 | } | |
409 | ||
410 | /** | |
411 | * blk_trace_ioctl: - handle the ioctls associated with tracing | |
412 | * @bdev: the block device | |
413 | * @cmd: the ioctl cmd | |
414 | * @arg: the argument data, if any | |
415 | * | |
416 | **/ | |
417 | int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg) | |
418 | { | |
419 | request_queue_t *q; | |
420 | int ret, start = 0; | |
421 | ||
422 | q = bdev_get_queue(bdev); | |
423 | if (!q) | |
424 | return -ENXIO; | |
425 | ||
426 | mutex_lock(&bdev->bd_mutex); | |
427 | ||
428 | switch (cmd) { | |
429 | case BLKTRACESETUP: | |
430 | ret = blk_trace_setup(q, bdev, arg); | |
431 | break; | |
432 | case BLKTRACESTART: | |
433 | start = 1; | |
434 | case BLKTRACESTOP: | |
435 | ret = blk_trace_startstop(q, start); | |
436 | break; | |
437 | case BLKTRACETEARDOWN: | |
438 | ret = blk_trace_remove(q); | |
439 | break; | |
440 | default: | |
441 | ret = -ENOTTY; | |
442 | break; | |
443 | } | |
444 | ||
445 | mutex_unlock(&bdev->bd_mutex); | |
446 | return ret; | |
447 | } | |
448 | ||
449 | /** | |
450 | * blk_trace_shutdown: - stop and cleanup trace structures | |
451 | * @q: the request queue associated with the device | |
452 | * | |
453 | **/ | |
454 | void blk_trace_shutdown(request_queue_t *q) | |
455 | { | |
6c5c9341 AD |
456 | if (q->blk_trace) { |
457 | blk_trace_startstop(q, 0); | |
458 | blk_trace_remove(q); | |
459 | } | |
2056a782 JA |
460 | } |
461 | ||
462 | /* | |
463 | * Average offset over two calls to sched_clock() with a gettimeofday() | |
464 | * in the middle | |
465 | */ | |
466 | static void blk_check_time(unsigned long long *t) | |
467 | { | |
468 | unsigned long long a, b; | |
469 | struct timeval tv; | |
470 | ||
471 | a = sched_clock(); | |
472 | do_gettimeofday(&tv); | |
473 | b = sched_clock(); | |
474 | ||
475 | *t = tv.tv_sec * 1000000000 + tv.tv_usec * 1000; | |
476 | *t -= (a + b) / 2; | |
477 | } | |
478 | ||
4090959a MP |
479 | /* |
480 | * calibrate our inter-CPU timings | |
481 | */ | |
2056a782 JA |
482 | static void blk_trace_check_cpu_time(void *data) |
483 | { | |
484 | unsigned long long *t; | |
485 | int cpu = get_cpu(); | |
486 | ||
487 | t = &per_cpu(blk_trace_cpu_offset, cpu); | |
488 | ||
489 | /* | |
490 | * Just call it twice, hopefully the second call will be cache hot | |
491 | * and a little more precise | |
492 | */ | |
493 | blk_check_time(t); | |
494 | blk_check_time(t); | |
495 | ||
496 | put_cpu(); | |
497 | } | |
498 | ||
2056a782 JA |
499 | static void blk_trace_set_ht_offsets(void) |
500 | { | |
501 | #if defined(CONFIG_SCHED_SMT) | |
502 | int cpu, i; | |
503 | ||
504 | /* | |
505 | * now make sure HT siblings have the same time offset | |
506 | */ | |
507 | preempt_disable(); | |
508 | for_each_online_cpu(cpu) { | |
509 | unsigned long long *cpu_off, *sibling_off; | |
510 | ||
511 | for_each_cpu_mask(i, cpu_sibling_map[cpu]) { | |
512 | if (i == cpu) | |
513 | continue; | |
514 | ||
515 | cpu_off = &per_cpu(blk_trace_cpu_offset, cpu); | |
516 | sibling_off = &per_cpu(blk_trace_cpu_offset, i); | |
517 | *sibling_off = *cpu_off; | |
518 | } | |
519 | } | |
520 | preempt_enable(); | |
521 | #endif | |
522 | } | |
523 | ||
524 | static __init int blk_trace_init(void) | |
525 | { | |
526 | mutex_init(&blk_tree_mutex); | |
4090959a | 527 | on_each_cpu(blk_trace_check_cpu_time, NULL, 1, 1); |
2056a782 JA |
528 | blk_trace_set_ht_offsets(); |
529 | ||
530 | return 0; | |
531 | } | |
532 | ||
533 | module_init(blk_trace_init); | |
534 |