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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/debugfs.h> 25 #include <linux/time.h> 26 #include <asm/uaccess.h> 27 28 static unsigned int blktrace_seq __read_mostly = 1; 29 30 /* 31 * Send out a notify message. 32 */ 33 static void trace_note(struct blk_trace *bt, pid_t pid, int action, 34 const void *data, size_t len) 35 { 36 struct blk_io_trace *t; 37 38 t = relay_reserve(bt->rchan, sizeof(*t) + len); 39 if (t) { 40 const int cpu = smp_processor_id(); 41 42 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; 43 t->time = ktime_to_ns(ktime_get()); 44 t->device = bt->dev; 45 t->action = action; 46 t->pid = pid; 47 t->cpu = cpu; 48 t->pdu_len = len; 49 memcpy((void *) t + sizeof(*t), data, len); 50 } 51 } 52 53 /* 54 * Send out a notify for this process, if we haven't done so since a trace 55 * started 56 */ 57 static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk) 58 { 59 tsk->btrace_seq = blktrace_seq; 60 trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm)); 61 } 62 63 static void trace_note_time(struct blk_trace *bt) 64 { 65 struct timespec now; 66 unsigned long flags; 67 u32 words[2]; 68 69 getnstimeofday(&now); 70 words[0] = now.tv_sec; 71 words[1] = now.tv_nsec; 72 73 local_irq_save(flags); 74 trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words)); 75 local_irq_restore(flags); 76 } 77 78 void __trace_note_message(struct blk_trace *bt, const char *fmt, ...) 79 { 80 int n; 81 va_list args; 82 unsigned long flags; 83 char *buf; 84 85 local_irq_save(flags); 86 buf = per_cpu_ptr(bt->msg_data, smp_processor_id()); 87 va_start(args, fmt); 88 n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args); 89 va_end(args); 90 91 trace_note(bt, 0, BLK_TN_MESSAGE, buf, n); 92 local_irq_restore(flags); 93 } 94 EXPORT_SYMBOL_GPL(__trace_note_message); 95 96 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector, 97 pid_t pid) 98 { 99 if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0) 100 return 1; 101 if (sector < bt->start_lba || sector > bt->end_lba) 102 return 1; 103 if (bt->pid && pid != bt->pid) 104 return 1; 105 106 return 0; 107 } 108 109 /* 110 * Data direction bit lookup 111 */ 112 static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ), BLK_TC_ACT(BLK_TC_WRITE) }; 113 114 /* The ilog2() calls fall out because they're constant */ 115 #define MASK_TC_BIT(rw, __name) ( (rw & (1 << BIO_RW_ ## __name)) << \ 116 (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - BIO_RW_ ## __name) ) 117 118 /* 119 * The worker for the various blk_add_trace*() types. Fills out a 120 * blk_io_trace structure and places it in a per-cpu subbuffer. 121 */ 122 void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, 123 int rw, u32 what, int error, int pdu_len, void *pdu_data) 124 { 125 struct task_struct *tsk = current; 126 struct blk_io_trace *t; 127 unsigned long flags; 128 unsigned long *sequence; 129 pid_t pid; 130 int cpu; 131 132 if (unlikely(bt->trace_state != Blktrace_running)) 133 return; 134 135 what |= ddir_act[rw & WRITE]; 136 what |= MASK_TC_BIT(rw, BARRIER); 137 what |= MASK_TC_BIT(rw, SYNC); 138 what |= MASK_TC_BIT(rw, AHEAD); 139 what |= MASK_TC_BIT(rw, META); 140 what |= MASK_TC_BIT(rw, DISCARD); 141 142 pid = tsk->pid; 143 if (unlikely(act_log_check(bt, what, sector, pid))) 144 return; 145 146 /* 147 * A word about the locking here - we disable interrupts to reserve 148 * some space in the relay per-cpu buffer, to prevent an irq 149 * from coming in and stepping on our toes. 150 */ 151 local_irq_save(flags); 152 153 if (unlikely(tsk->btrace_seq != blktrace_seq)) 154 trace_note_tsk(bt, tsk); 155 156 t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len); 157 if (t) { 158 cpu = smp_processor_id(); 159 sequence = per_cpu_ptr(bt->sequence, cpu); 160 161 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; 162 t->sequence = ++(*sequence); 163 t->time = ktime_to_ns(ktime_get()); 164 t->sector = sector; 165 t->bytes = bytes; 166 t->action = what; 167 t->pid = pid; 168 t->device = bt->dev; 169 t->cpu = cpu; 170 t->error = error; 171 t->pdu_len = pdu_len; 172 173 if (pdu_len) 174 memcpy((void *) t + sizeof(*t), pdu_data, pdu_len); 175 } 176 177 local_irq_restore(flags); 178 } 179 180 EXPORT_SYMBOL_GPL(__blk_add_trace); 181 182 static struct dentry *blk_tree_root; 183 static DEFINE_MUTEX(blk_tree_mutex); 184 static unsigned int root_users; 185 186 static inline void blk_remove_root(void) 187 { 188 if (blk_tree_root) { 189 debugfs_remove(blk_tree_root); 190 blk_tree_root = NULL; 191 } 192 } 193 194 static void blk_remove_tree(struct dentry *dir) 195 { 196 mutex_lock(&blk_tree_mutex); 197 debugfs_remove(dir); 198 if (--root_users == 0) 199 blk_remove_root(); 200 mutex_unlock(&blk_tree_mutex); 201 } 202 203 static struct dentry *blk_create_tree(const char *blk_name) 204 { 205 struct dentry *dir = NULL; 206 int created = 0; 207 208 mutex_lock(&blk_tree_mutex); 209 210 if (!blk_tree_root) { 211 blk_tree_root = debugfs_create_dir("block", NULL); 212 if (!blk_tree_root) 213 goto err; 214 created = 1; 215 } 216 217 dir = debugfs_create_dir(blk_name, blk_tree_root); 218 if (dir) 219 root_users++; 220 else { 221 /* Delete root only if we created it */ 222 if (created) 223 blk_remove_root(); 224 } 225 226 err: 227 mutex_unlock(&blk_tree_mutex); 228 return dir; 229 } 230 231 static void blk_trace_cleanup(struct blk_trace *bt) 232 { 233 relay_close(bt->rchan); 234 debugfs_remove(bt->msg_file); 235 debugfs_remove(bt->dropped_file); 236 blk_remove_tree(bt->dir); 237 free_percpu(bt->sequence); 238 free_percpu(bt->msg_data); 239 kfree(bt); 240 } 241 242 int blk_trace_remove(struct request_queue *q) 243 { 244 struct blk_trace *bt; 245 246 bt = xchg(&q->blk_trace, NULL); 247 if (!bt) 248 return -EINVAL; 249 250 if (bt->trace_state == Blktrace_setup || 251 bt->trace_state == Blktrace_stopped) 252 blk_trace_cleanup(bt); 253 254 return 0; 255 } 256 EXPORT_SYMBOL_GPL(blk_trace_remove); 257 258 static int blk_dropped_open(struct inode *inode, struct file *filp) 259 { 260 filp->private_data = inode->i_private; 261 262 return 0; 263 } 264 265 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer, 266 size_t count, loff_t *ppos) 267 { 268 struct blk_trace *bt = filp->private_data; 269 char buf[16]; 270 271 snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped)); 272 273 return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf)); 274 } 275 276 static const struct file_operations blk_dropped_fops = { 277 .owner = THIS_MODULE, 278 .open = blk_dropped_open, 279 .read = blk_dropped_read, 280 }; 281 282 static int blk_msg_open(struct inode *inode, struct file *filp) 283 { 284 filp->private_data = inode->i_private; 285 286 return 0; 287 } 288 289 static ssize_t blk_msg_write(struct file *filp, const char __user *buffer, 290 size_t count, loff_t *ppos) 291 { 292 char *msg; 293 struct blk_trace *bt; 294 295 if (count > BLK_TN_MAX_MSG) 296 return -EINVAL; 297 298 msg = kmalloc(count, GFP_KERNEL); 299 if (msg == NULL) 300 return -ENOMEM; 301 302 if (copy_from_user(msg, buffer, count)) { 303 kfree(msg); 304 return -EFAULT; 305 } 306 307 bt = filp->private_data; 308 __trace_note_message(bt, "%s", msg); 309 kfree(msg); 310 311 return count; 312 } 313 314 static const struct file_operations blk_msg_fops = { 315 .owner = THIS_MODULE, 316 .open = blk_msg_open, 317 .write = blk_msg_write, 318 }; 319 320 /* 321 * Keep track of how many times we encountered a full subbuffer, to aid 322 * the user space app in telling how many lost events there were. 323 */ 324 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf, 325 void *prev_subbuf, size_t prev_padding) 326 { 327 struct blk_trace *bt; 328 329 if (!relay_buf_full(buf)) 330 return 1; 331 332 bt = buf->chan->private_data; 333 atomic_inc(&bt->dropped); 334 return 0; 335 } 336 337 static int blk_remove_buf_file_callback(struct dentry *dentry) 338 { 339 debugfs_remove(dentry); 340 return 0; 341 } 342 343 static struct dentry *blk_create_buf_file_callback(const char *filename, 344 struct dentry *parent, 345 int mode, 346 struct rchan_buf *buf, 347 int *is_global) 348 { 349 return debugfs_create_file(filename, mode, parent, buf, 350 &relay_file_operations); 351 } 352 353 static struct rchan_callbacks blk_relay_callbacks = { 354 .subbuf_start = blk_subbuf_start_callback, 355 .create_buf_file = blk_create_buf_file_callback, 356 .remove_buf_file = blk_remove_buf_file_callback, 357 }; 358 359 /* 360 * Setup everything required to start tracing 361 */ 362 int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, 363 struct blk_user_trace_setup *buts) 364 { 365 struct blk_trace *old_bt, *bt = NULL; 366 struct dentry *dir = NULL; 367 int ret, i; 368 369 if (!buts->buf_size || !buts->buf_nr) 370 return -EINVAL; 371 372 strncpy(buts->name, name, BLKTRACE_BDEV_SIZE); 373 buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0'; 374 375 /* 376 * some device names have larger paths - convert the slashes 377 * to underscores for this to work as expected 378 */ 379 for (i = 0; i < strlen(buts->name); i++) 380 if (buts->name[i] == '/') 381 buts->name[i] = '_'; 382 383 ret = -ENOMEM; 384 bt = kzalloc(sizeof(*bt), GFP_KERNEL); 385 if (!bt) 386 goto err; 387 388 bt->sequence = alloc_percpu(unsigned long); 389 if (!bt->sequence) 390 goto err; 391 392 bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG); 393 if (!bt->msg_data) 394 goto err; 395 396 ret = -ENOENT; 397 dir = blk_create_tree(buts->name); 398 if (!dir) 399 goto err; 400 401 bt->dir = dir; 402 bt->dev = dev; 403 atomic_set(&bt->dropped, 0); 404 405 ret = -EIO; 406 bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops); 407 if (!bt->dropped_file) 408 goto err; 409 410 bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops); 411 if (!bt->msg_file) 412 goto err; 413 414 bt->rchan = relay_open("trace", dir, buts->buf_size, 415 buts->buf_nr, &blk_relay_callbacks, bt); 416 if (!bt->rchan) 417 goto err; 418 419 bt->act_mask = buts->act_mask; 420 if (!bt->act_mask) 421 bt->act_mask = (u16) -1; 422 423 bt->start_lba = buts->start_lba; 424 bt->end_lba = buts->end_lba; 425 if (!bt->end_lba) 426 bt->end_lba = -1ULL; 427 428 bt->pid = buts->pid; 429 bt->trace_state = Blktrace_setup; 430 431 ret = -EBUSY; 432 old_bt = xchg(&q->blk_trace, bt); 433 if (old_bt) { 434 (void) xchg(&q->blk_trace, old_bt); 435 goto err; 436 } 437 438 return 0; 439 err: 440 if (dir) 441 blk_remove_tree(dir); 442 if (bt) { 443 if (bt->msg_file) 444 debugfs_remove(bt->msg_file); 445 if (bt->dropped_file) 446 debugfs_remove(bt->dropped_file); 447 free_percpu(bt->sequence); 448 free_percpu(bt->msg_data); 449 if (bt->rchan) 450 relay_close(bt->rchan); 451 kfree(bt); 452 } 453 return ret; 454 } 455 456 int blk_trace_setup(struct request_queue *q, char *name, dev_t dev, 457 char __user *arg) 458 { 459 struct blk_user_trace_setup buts; 460 int ret; 461 462 ret = copy_from_user(&buts, arg, sizeof(buts)); 463 if (ret) 464 return -EFAULT; 465 466 ret = do_blk_trace_setup(q, name, dev, &buts); 467 if (ret) 468 return ret; 469 470 if (copy_to_user(arg, &buts, sizeof(buts))) 471 return -EFAULT; 472 473 return 0; 474 } 475 EXPORT_SYMBOL_GPL(blk_trace_setup); 476 477 int blk_trace_startstop(struct request_queue *q, int start) 478 { 479 struct blk_trace *bt; 480 int ret; 481 482 if ((bt = q->blk_trace) == NULL) 483 return -EINVAL; 484 485 /* 486 * For starting a trace, we can transition from a setup or stopped 487 * trace. For stopping a trace, the state must be running 488 */ 489 ret = -EINVAL; 490 if (start) { 491 if (bt->trace_state == Blktrace_setup || 492 bt->trace_state == Blktrace_stopped) { 493 blktrace_seq++; 494 smp_mb(); 495 bt->trace_state = Blktrace_running; 496 497 trace_note_time(bt); 498 ret = 0; 499 } 500 } else { 501 if (bt->trace_state == Blktrace_running) { 502 bt->trace_state = Blktrace_stopped; 503 relay_flush(bt->rchan); 504 ret = 0; 505 } 506 } 507 508 return ret; 509 } 510 EXPORT_SYMBOL_GPL(blk_trace_startstop); 511 512 /** 513 * blk_trace_ioctl: - handle the ioctls associated with tracing 514 * @bdev: the block device 515 * @cmd: the ioctl cmd 516 * @arg: the argument data, if any 517 * 518 **/ 519 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg) 520 { 521 struct request_queue *q; 522 int ret, start = 0; 523 char b[BDEVNAME_SIZE]; 524 525 q = bdev_get_queue(bdev); 526 if (!q) 527 return -ENXIO; 528 529 mutex_lock(&bdev->bd_mutex); 530 531 switch (cmd) { 532 case BLKTRACESETUP: 533 bdevname(bdev, b); 534 ret = blk_trace_setup(q, b, bdev->bd_dev, arg); 535 break; 536 case BLKTRACESTART: 537 start = 1; 538 case BLKTRACESTOP: 539 ret = blk_trace_startstop(q, start); 540 break; 541 case BLKTRACETEARDOWN: 542 ret = blk_trace_remove(q); 543 break; 544 default: 545 ret = -ENOTTY; 546 break; 547 } 548 549 mutex_unlock(&bdev->bd_mutex); 550 return ret; 551 } 552 553 /** 554 * blk_trace_shutdown: - stop and cleanup trace structures 555 * @q: the request queue associated with the device 556 * 557 **/ 558 void blk_trace_shutdown(struct request_queue *q) 559 { 560 if (q->blk_trace) { 561 blk_trace_startstop(q, 0); 562 blk_trace_remove(q); 563 } 564 } 565
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