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2056a782 JA |
1 | /* |
2 | * Copyright (C) 2006 Jens Axboe <axboe@suse.de> | |
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 | */ | |
72 | static u32 bio_act[3] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC) }; | |
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)) | |
82 | ||
83 | /* | |
84 | * The worker for the various blk_add_trace*() types. Fills out a | |
85 | * blk_io_trace structure and places it in a per-cpu subbuffer. | |
86 | */ | |
87 | void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, | |
88 | int rw, u32 what, int error, int pdu_len, void *pdu_data) | |
89 | { | |
90 | struct task_struct *tsk = current; | |
91 | struct blk_io_trace *t; | |
92 | unsigned long flags; | |
93 | unsigned long *sequence; | |
94 | pid_t pid; | |
95 | int cpu; | |
96 | ||
97 | if (unlikely(bt->trace_state != Blktrace_running)) | |
98 | return; | |
99 | ||
100 | what |= ddir_act[rw & WRITE]; | |
101 | what |= bio_act[trace_barrier_bit(rw)]; | |
102 | what |= bio_act[trace_sync_bit(rw)]; | |
103 | ||
104 | pid = tsk->pid; | |
105 | if (unlikely(act_log_check(bt, what, sector, pid))) | |
106 | return; | |
107 | ||
108 | /* | |
109 | * A word about the locking here - we disable interrupts to reserve | |
110 | * some space in the relay per-cpu buffer, to prevent an irq | |
111 | * from coming in and stepping on our toes. Once reserved, it's | |
112 | * enough to get preemption disabled to prevent read of this data | |
113 | * before we are through filling it. get_cpu()/put_cpu() does this | |
114 | * for us | |
115 | */ | |
116 | local_irq_save(flags); | |
117 | ||
118 | if (unlikely(tsk->btrace_seq != blktrace_seq)) | |
119 | trace_note_tsk(bt, tsk); | |
120 | ||
121 | t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len); | |
122 | if (t) { | |
123 | cpu = smp_processor_id(); | |
124 | sequence = per_cpu_ptr(bt->sequence, cpu); | |
125 | ||
126 | t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; | |
127 | t->sequence = ++(*sequence); | |
128 | t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu); | |
129 | t->sector = sector; | |
130 | t->bytes = bytes; | |
131 | t->action = what; | |
132 | t->pid = pid; | |
133 | t->device = bt->dev; | |
134 | t->cpu = cpu; | |
135 | t->error = error; | |
136 | t->pdu_len = pdu_len; | |
137 | ||
138 | if (pdu_len) | |
139 | memcpy((void *) t + sizeof(*t), pdu_data, pdu_len); | |
140 | } | |
141 | ||
142 | local_irq_restore(flags); | |
143 | } | |
144 | ||
145 | EXPORT_SYMBOL_GPL(__blk_add_trace); | |
146 | ||
147 | static struct dentry *blk_tree_root; | |
148 | static struct mutex blk_tree_mutex; | |
149 | static unsigned int root_users; | |
150 | ||
151 | static inline void blk_remove_root(void) | |
152 | { | |
153 | if (blk_tree_root) { | |
154 | debugfs_remove(blk_tree_root); | |
155 | blk_tree_root = NULL; | |
156 | } | |
157 | } | |
158 | ||
159 | static void blk_remove_tree(struct dentry *dir) | |
160 | { | |
161 | mutex_lock(&blk_tree_mutex); | |
162 | debugfs_remove(dir); | |
163 | if (--root_users == 0) | |
164 | blk_remove_root(); | |
165 | mutex_unlock(&blk_tree_mutex); | |
166 | } | |
167 | ||
168 | static struct dentry *blk_create_tree(const char *blk_name) | |
169 | { | |
170 | struct dentry *dir = NULL; | |
171 | ||
172 | mutex_lock(&blk_tree_mutex); | |
173 | ||
174 | if (!blk_tree_root) { | |
175 | blk_tree_root = debugfs_create_dir("block", NULL); | |
176 | if (!blk_tree_root) | |
177 | goto err; | |
178 | } | |
179 | ||
180 | dir = debugfs_create_dir(blk_name, blk_tree_root); | |
181 | if (dir) | |
182 | root_users++; | |
183 | else | |
184 | blk_remove_root(); | |
185 | ||
186 | err: | |
187 | mutex_unlock(&blk_tree_mutex); | |
188 | return dir; | |
189 | } | |
190 | ||
191 | static void blk_trace_cleanup(struct blk_trace *bt) | |
192 | { | |
193 | relay_close(bt->rchan); | |
194 | debugfs_remove(bt->dropped_file); | |
195 | blk_remove_tree(bt->dir); | |
196 | free_percpu(bt->sequence); | |
197 | kfree(bt); | |
198 | } | |
199 | ||
200 | static int blk_trace_remove(request_queue_t *q) | |
201 | { | |
202 | struct blk_trace *bt; | |
203 | ||
204 | bt = xchg(&q->blk_trace, NULL); | |
205 | if (!bt) | |
206 | return -EINVAL; | |
207 | ||
208 | if (bt->trace_state == Blktrace_setup || | |
209 | bt->trace_state == Blktrace_stopped) | |
210 | blk_trace_cleanup(bt); | |
211 | ||
212 | return 0; | |
213 | } | |
214 | ||
215 | static int blk_dropped_open(struct inode *inode, struct file *filp) | |
216 | { | |
217 | filp->private_data = inode->u.generic_ip; | |
218 | ||
219 | return 0; | |
220 | } | |
221 | ||
222 | static ssize_t blk_dropped_read(struct file *filp, char __user *buffer, | |
223 | size_t count, loff_t *ppos) | |
224 | { | |
225 | struct blk_trace *bt = filp->private_data; | |
226 | char buf[16]; | |
227 | ||
228 | snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped)); | |
229 | ||
230 | return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf)); | |
231 | } | |
232 | ||
233 | static struct file_operations blk_dropped_fops = { | |
234 | .owner = THIS_MODULE, | |
235 | .open = blk_dropped_open, | |
236 | .read = blk_dropped_read, | |
237 | }; | |
238 | ||
239 | /* | |
240 | * Keep track of how many times we encountered a full subbuffer, to aid | |
241 | * the user space app in telling how many lost events there were. | |
242 | */ | |
243 | static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf, | |
244 | void *prev_subbuf, size_t prev_padding) | |
245 | { | |
246 | struct blk_trace *bt; | |
247 | ||
248 | if (!relay_buf_full(buf)) | |
249 | return 1; | |
250 | ||
251 | bt = buf->chan->private_data; | |
252 | atomic_inc(&bt->dropped); | |
253 | return 0; | |
254 | } | |
255 | ||
256 | static int blk_remove_buf_file_callback(struct dentry *dentry) | |
257 | { | |
258 | debugfs_remove(dentry); | |
259 | return 0; | |
260 | } | |
261 | ||
262 | static struct dentry *blk_create_buf_file_callback(const char *filename, | |
263 | struct dentry *parent, | |
264 | int mode, | |
265 | struct rchan_buf *buf, | |
266 | int *is_global) | |
267 | { | |
268 | return debugfs_create_file(filename, mode, parent, buf, | |
269 | &relay_file_operations); | |
270 | } | |
271 | ||
272 | static struct rchan_callbacks blk_relay_callbacks = { | |
273 | .subbuf_start = blk_subbuf_start_callback, | |
274 | .create_buf_file = blk_create_buf_file_callback, | |
275 | .remove_buf_file = blk_remove_buf_file_callback, | |
276 | }; | |
277 | ||
278 | /* | |
279 | * Setup everything required to start tracing | |
280 | */ | |
281 | static int blk_trace_setup(request_queue_t *q, struct block_device *bdev, | |
282 | char __user *arg) | |
283 | { | |
284 | struct blk_user_trace_setup buts; | |
285 | struct blk_trace *old_bt, *bt = NULL; | |
286 | struct dentry *dir = NULL; | |
287 | char b[BDEVNAME_SIZE]; | |
288 | int ret, i; | |
289 | ||
290 | if (copy_from_user(&buts, arg, sizeof(buts))) | |
291 | return -EFAULT; | |
292 | ||
293 | if (!buts.buf_size || !buts.buf_nr) | |
294 | return -EINVAL; | |
295 | ||
296 | strcpy(buts.name, bdevname(bdev, b)); | |
297 | ||
298 | /* | |
299 | * some device names have larger paths - convert the slashes | |
300 | * to underscores for this to work as expected | |
301 | */ | |
302 | for (i = 0; i < strlen(buts.name); i++) | |
303 | if (buts.name[i] == '/') | |
304 | buts.name[i] = '_'; | |
305 | ||
306 | if (copy_to_user(arg, &buts, sizeof(buts))) | |
307 | return -EFAULT; | |
308 | ||
309 | ret = -ENOMEM; | |
310 | bt = kzalloc(sizeof(*bt), GFP_KERNEL); | |
311 | if (!bt) | |
312 | goto err; | |
313 | ||
314 | bt->sequence = alloc_percpu(unsigned long); | |
315 | if (!bt->sequence) | |
316 | goto err; | |
317 | ||
318 | ret = -ENOENT; | |
319 | dir = blk_create_tree(buts.name); | |
320 | if (!dir) | |
321 | goto err; | |
322 | ||
323 | bt->dir = dir; | |
324 | bt->dev = bdev->bd_dev; | |
325 | atomic_set(&bt->dropped, 0); | |
326 | ||
327 | ret = -EIO; | |
328 | bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops); | |
329 | if (!bt->dropped_file) | |
330 | goto err; | |
331 | ||
332 | bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, &blk_relay_callbacks); | |
333 | if (!bt->rchan) | |
334 | goto err; | |
335 | bt->rchan->private_data = bt; | |
336 | ||
337 | bt->act_mask = buts.act_mask; | |
338 | if (!bt->act_mask) | |
339 | bt->act_mask = (u16) -1; | |
340 | ||
341 | bt->start_lba = buts.start_lba; | |
342 | bt->end_lba = buts.end_lba; | |
343 | if (!bt->end_lba) | |
344 | bt->end_lba = -1ULL; | |
345 | ||
346 | bt->pid = buts.pid; | |
347 | bt->trace_state = Blktrace_setup; | |
348 | ||
349 | ret = -EBUSY; | |
350 | old_bt = xchg(&q->blk_trace, bt); | |
351 | if (old_bt) { | |
352 | (void) xchg(&q->blk_trace, old_bt); | |
353 | goto err; | |
354 | } | |
355 | ||
356 | return 0; | |
357 | err: | |
358 | if (dir) | |
359 | blk_remove_tree(dir); | |
360 | if (bt) { | |
361 | if (bt->dropped_file) | |
362 | debugfs_remove(bt->dropped_file); | |
363 | if (bt->sequence) | |
364 | free_percpu(bt->sequence); | |
365 | if (bt->rchan) | |
366 | relay_close(bt->rchan); | |
367 | kfree(bt); | |
368 | } | |
369 | return ret; | |
370 | } | |
371 | ||
372 | static int blk_trace_startstop(request_queue_t *q, int start) | |
373 | { | |
374 | struct blk_trace *bt; | |
375 | int ret; | |
376 | ||
377 | if ((bt = q->blk_trace) == NULL) | |
378 | return -EINVAL; | |
379 | ||
380 | /* | |
381 | * For starting a trace, we can transition from a setup or stopped | |
382 | * trace. For stopping a trace, the state must be running | |
383 | */ | |
384 | ret = -EINVAL; | |
385 | if (start) { | |
386 | if (bt->trace_state == Blktrace_setup || | |
387 | bt->trace_state == Blktrace_stopped) { | |
388 | blktrace_seq++; | |
389 | smp_mb(); | |
390 | bt->trace_state = Blktrace_running; | |
391 | ret = 0; | |
392 | } | |
393 | } else { | |
394 | if (bt->trace_state == Blktrace_running) { | |
395 | bt->trace_state = Blktrace_stopped; | |
396 | relay_flush(bt->rchan); | |
397 | ret = 0; | |
398 | } | |
399 | } | |
400 | ||
401 | return ret; | |
402 | } | |
403 | ||
404 | /** | |
405 | * blk_trace_ioctl: - handle the ioctls associated with tracing | |
406 | * @bdev: the block device | |
407 | * @cmd: the ioctl cmd | |
408 | * @arg: the argument data, if any | |
409 | * | |
410 | **/ | |
411 | int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg) | |
412 | { | |
413 | request_queue_t *q; | |
414 | int ret, start = 0; | |
415 | ||
416 | q = bdev_get_queue(bdev); | |
417 | if (!q) | |
418 | return -ENXIO; | |
419 | ||
420 | mutex_lock(&bdev->bd_mutex); | |
421 | ||
422 | switch (cmd) { | |
423 | case BLKTRACESETUP: | |
424 | ret = blk_trace_setup(q, bdev, arg); | |
425 | break; | |
426 | case BLKTRACESTART: | |
427 | start = 1; | |
428 | case BLKTRACESTOP: | |
429 | ret = blk_trace_startstop(q, start); | |
430 | break; | |
431 | case BLKTRACETEARDOWN: | |
432 | ret = blk_trace_remove(q); | |
433 | break; | |
434 | default: | |
435 | ret = -ENOTTY; | |
436 | break; | |
437 | } | |
438 | ||
439 | mutex_unlock(&bdev->bd_mutex); | |
440 | return ret; | |
441 | } | |
442 | ||
443 | /** | |
444 | * blk_trace_shutdown: - stop and cleanup trace structures | |
445 | * @q: the request queue associated with the device | |
446 | * | |
447 | **/ | |
448 | void blk_trace_shutdown(request_queue_t *q) | |
449 | { | |
450 | blk_trace_startstop(q, 0); | |
451 | blk_trace_remove(q); | |
452 | } | |
453 | ||
454 | /* | |
455 | * Average offset over two calls to sched_clock() with a gettimeofday() | |
456 | * in the middle | |
457 | */ | |
458 | static void blk_check_time(unsigned long long *t) | |
459 | { | |
460 | unsigned long long a, b; | |
461 | struct timeval tv; | |
462 | ||
463 | a = sched_clock(); | |
464 | do_gettimeofday(&tv); | |
465 | b = sched_clock(); | |
466 | ||
467 | *t = tv.tv_sec * 1000000000 + tv.tv_usec * 1000; | |
468 | *t -= (a + b) / 2; | |
469 | } | |
470 | ||
471 | static void blk_trace_check_cpu_time(void *data) | |
472 | { | |
473 | unsigned long long *t; | |
474 | int cpu = get_cpu(); | |
475 | ||
476 | t = &per_cpu(blk_trace_cpu_offset, cpu); | |
477 | ||
478 | /* | |
479 | * Just call it twice, hopefully the second call will be cache hot | |
480 | * and a little more precise | |
481 | */ | |
482 | blk_check_time(t); | |
483 | blk_check_time(t); | |
484 | ||
485 | put_cpu(); | |
486 | } | |
487 | ||
488 | /* | |
489 | * Call blk_trace_check_cpu_time() on each CPU to calibrate our inter-CPU | |
490 | * timings | |
491 | */ | |
492 | static void blk_trace_calibrate_offsets(void) | |
493 | { | |
494 | unsigned long flags; | |
495 | ||
496 | smp_call_function(blk_trace_check_cpu_time, NULL, 1, 1); | |
497 | local_irq_save(flags); | |
498 | blk_trace_check_cpu_time(NULL); | |
499 | local_irq_restore(flags); | |
500 | } | |
501 | ||
502 | static void blk_trace_set_ht_offsets(void) | |
503 | { | |
504 | #if defined(CONFIG_SCHED_SMT) | |
505 | int cpu, i; | |
506 | ||
507 | /* | |
508 | * now make sure HT siblings have the same time offset | |
509 | */ | |
510 | preempt_disable(); | |
511 | for_each_online_cpu(cpu) { | |
512 | unsigned long long *cpu_off, *sibling_off; | |
513 | ||
514 | for_each_cpu_mask(i, cpu_sibling_map[cpu]) { | |
515 | if (i == cpu) | |
516 | continue; | |
517 | ||
518 | cpu_off = &per_cpu(blk_trace_cpu_offset, cpu); | |
519 | sibling_off = &per_cpu(blk_trace_cpu_offset, i); | |
520 | *sibling_off = *cpu_off; | |
521 | } | |
522 | } | |
523 | preempt_enable(); | |
524 | #endif | |
525 | } | |
526 | ||
527 | static __init int blk_trace_init(void) | |
528 | { | |
529 | mutex_init(&blk_tree_mutex); | |
530 | blk_trace_calibrate_offsets(); | |
531 | blk_trace_set_ht_offsets(); | |
532 | ||
533 | return 0; | |
534 | } | |
535 | ||
536 | module_init(blk_trace_init); | |
537 |