1/* 2 * Copyright (C) 2011 STRATO. All rights reserved. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public 6 * License v2 as 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 GNU 11 * General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public 14 * License along with this program; if not, write to the 15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 16 * Boston, MA 021110-1307, USA. 17 */ 18 19#include <linux/sched.h> 20#include <linux/pagemap.h> 21#include <linux/writeback.h> 22#include <linux/blkdev.h> 23#include <linux/rbtree.h> 24#include <linux/slab.h> 25#include <linux/workqueue.h> 26#include "ctree.h" 27#include "volumes.h" 28#include "disk-io.h" 29#include "transaction.h" 30#include "dev-replace.h" 31 32#undef DEBUG 33 34/* 35 * This is the implementation for the generic read ahead framework. 36 * 37 * To trigger a readahead, btrfs_reada_add must be called. It will start 38 * a read ahead for the given range [start, end) on tree root. The returned 39 * handle can either be used to wait on the readahead to finish 40 * (btrfs_reada_wait), or to send it to the background (btrfs_reada_detach). 41 * 42 * The read ahead works as follows: 43 * On btrfs_reada_add, the root of the tree is inserted into a radix_tree. 44 * reada_start_machine will then search for extents to prefetch and trigger 45 * some reads. When a read finishes for a node, all contained node/leaf 46 * pointers that lie in the given range will also be enqueued. The reads will 47 * be triggered in sequential order, thus giving a big win over a naive 48 * enumeration. It will also make use of multi-device layouts. Each disk 49 * will have its on read pointer and all disks will by utilized in parallel. 50 * Also will no two disks read both sides of a mirror simultaneously, as this 51 * would waste seeking capacity. Instead both disks will read different parts 52 * of the filesystem. 53 * Any number of readaheads can be started in parallel. The read order will be 54 * determined globally, i.e. 2 parallel readaheads will normally finish faster 55 * than the 2 started one after another. 56 */ 57 58#define MAX_IN_FLIGHT 6 59 60struct reada_extctl { 61 struct list_head list; 62 struct reada_control *rc; 63 u64 generation; 64}; 65 66struct reada_extent { 67 u64 logical; 68 struct btrfs_key top; 69 int err; 70 struct list_head extctl; 71 int refcnt; 72 spinlock_t lock; 73 struct reada_zone *zones[BTRFS_MAX_MIRRORS]; 74 int nzones; 75 struct btrfs_device *scheduled_for; 76}; 77 78struct reada_zone { 79 u64 start; 80 u64 end; 81 u64 elems; 82 struct list_head list; 83 spinlock_t lock; 84 int locked; 85 struct btrfs_device *device; 86 struct btrfs_device *devs[BTRFS_MAX_MIRRORS]; /* full list, incl 87 * self */ 88 int ndevs; 89 struct kref refcnt; 90}; 91 92struct reada_machine_work { 93 struct btrfs_work work; 94 struct btrfs_fs_info *fs_info; 95}; 96 97static void reada_extent_put(struct btrfs_fs_info *, struct reada_extent *); 98static void reada_control_release(struct kref *kref); 99static void reada_zone_release(struct kref *kref); 100static void reada_start_machine(struct btrfs_fs_info *fs_info); 101static void __reada_start_machine(struct btrfs_fs_info *fs_info); 102 103static int reada_add_block(struct reada_control *rc, u64 logical, 104 struct btrfs_key *top, int level, u64 generation); 105 106/* recurses */ 107/* in case of err, eb might be NULL */ 108static int __readahead_hook(struct btrfs_root *root, struct extent_buffer *eb, 109 u64 start, int err) 110{ 111 int level = 0; 112 int nritems; 113 int i; 114 u64 bytenr; 115 u64 generation; 116 struct reada_extent *re; 117 struct btrfs_fs_info *fs_info = root->fs_info; 118 struct list_head list; 119 unsigned long index = start >> PAGE_CACHE_SHIFT; 120 struct btrfs_device *for_dev; 121 122 if (eb) 123 level = btrfs_header_level(eb); 124 125 /* find extent */ 126 spin_lock(&fs_info->reada_lock); 127 re = radix_tree_lookup(&fs_info->reada_tree, index); 128 if (re) 129 re->refcnt++; 130 spin_unlock(&fs_info->reada_lock); 131 132 if (!re) 133 return -1; 134 135 spin_lock(&re->lock); 136 /* 137 * just take the full list from the extent. afterwards we 138 * don't need the lock anymore 139 */ 140 list_replace_init(&re->extctl, &list); 141 for_dev = re->scheduled_for; 142 re->scheduled_for = NULL; 143 spin_unlock(&re->lock); 144 145 if (err == 0) { 146 nritems = level ? btrfs_header_nritems(eb) : 0; 147 generation = btrfs_header_generation(eb); 148 /* 149 * FIXME: currently we just set nritems to 0 if this is a leaf, 150 * effectively ignoring the content. In a next step we could 151 * trigger more readahead depending from the content, e.g. 152 * fetch the checksums for the extents in the leaf. 153 */ 154 } else { 155 /* 156 * this is the error case, the extent buffer has not been 157 * read correctly. We won't access anything from it and 158 * just cleanup our data structures. Effectively this will 159 * cut the branch below this node from read ahead. 160 */ 161 nritems = 0; 162 generation = 0; 163 } 164 165 for (i = 0; i < nritems; i++) { 166 struct reada_extctl *rec; 167 u64 n_gen; 168 struct btrfs_key key; 169 struct btrfs_key next_key; 170 171 btrfs_node_key_to_cpu(eb, &key, i); 172 if (i + 1 < nritems) 173 btrfs_node_key_to_cpu(eb, &next_key, i + 1); 174 else 175 next_key = re->top; 176 bytenr = btrfs_node_blockptr(eb, i); 177 n_gen = btrfs_node_ptr_generation(eb, i); 178 179 list_for_each_entry(rec, &list, list) { 180 struct reada_control *rc = rec->rc; 181 182 /* 183 * if the generation doesn't match, just ignore this 184 * extctl. This will probably cut off a branch from 185 * prefetch. Alternatively one could start a new (sub-) 186 * prefetch for this branch, starting again from root. 187 * FIXME: move the generation check out of this loop 188 */ 189#ifdef DEBUG 190 if (rec->generation != generation) { 191 btrfs_debug(root->fs_info, 192 "generation mismatch for (%llu,%d,%llu) %llu != %llu", 193 key.objectid, key.type, key.offset, 194 rec->generation, generation); 195 } 196#endif 197 if (rec->generation == generation && 198 btrfs_comp_cpu_keys(&key, &rc->key_end) < 0 && 199 btrfs_comp_cpu_keys(&next_key, &rc->key_start) > 0) 200 reada_add_block(rc, bytenr, &next_key, 201 level - 1, n_gen); 202 } 203 } 204 /* 205 * free extctl records 206 */ 207 while (!list_empty(&list)) { 208 struct reada_control *rc; 209 struct reada_extctl *rec; 210 211 rec = list_first_entry(&list, struct reada_extctl, list); 212 list_del(&rec->list); 213 rc = rec->rc; 214 kfree(rec); 215 216 kref_get(&rc->refcnt); 217 if (atomic_dec_and_test(&rc->elems)) { 218 kref_put(&rc->refcnt, reada_control_release); 219 wake_up(&rc->wait); 220 } 221 kref_put(&rc->refcnt, reada_control_release); 222 223 reada_extent_put(fs_info, re); /* one ref for each entry */ 224 } 225 reada_extent_put(fs_info, re); /* our ref */ 226 if (for_dev) 227 atomic_dec(&for_dev->reada_in_flight); 228 229 return 0; 230} 231 232/* 233 * start is passed separately in case eb in NULL, which may be the case with 234 * failed I/O 235 */ 236int btree_readahead_hook(struct btrfs_root *root, struct extent_buffer *eb, 237 u64 start, int err) 238{ 239 int ret; 240 241 ret = __readahead_hook(root, eb, start, err); 242 243 reada_start_machine(root->fs_info); 244 245 return ret; 246} 247 248static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info, 249 struct btrfs_device *dev, u64 logical, 250 struct btrfs_bio *bbio) 251{ 252 int ret; 253 struct reada_zone *zone; 254 struct btrfs_block_group_cache *cache = NULL; 255 u64 start; 256 u64 end; 257 int i; 258 259 zone = NULL; 260 spin_lock(&fs_info->reada_lock); 261 ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone, 262 logical >> PAGE_CACHE_SHIFT, 1); 263 if (ret == 1) 264 kref_get(&zone->refcnt); 265 spin_unlock(&fs_info->reada_lock); 266 267 if (ret == 1) { 268 if (logical >= zone->start && logical < zone->end) 269 return zone; 270 spin_lock(&fs_info->reada_lock); 271 kref_put(&zone->refcnt, reada_zone_release); 272 spin_unlock(&fs_info->reada_lock); 273 } 274 275 cache = btrfs_lookup_block_group(fs_info, logical); 276 if (!cache) 277 return NULL; 278 279 start = cache->key.objectid; 280 end = start + cache->key.offset - 1; 281 btrfs_put_block_group(cache); 282 283 zone = kzalloc(sizeof(*zone), GFP_NOFS); 284 if (!zone) 285 return NULL; 286 287 zone->start = start; 288 zone->end = end; 289 INIT_LIST_HEAD(&zone->list); 290 spin_lock_init(&zone->lock); 291 zone->locked = 0; 292 kref_init(&zone->refcnt); 293 zone->elems = 0; 294 zone->device = dev; /* our device always sits at index 0 */ 295 for (i = 0; i < bbio->num_stripes; ++i) { 296 /* bounds have already been checked */ 297 zone->devs[i] = bbio->stripes[i].dev; 298 } 299 zone->ndevs = bbio->num_stripes; 300 301 spin_lock(&fs_info->reada_lock); 302 ret = radix_tree_insert(&dev->reada_zones, 303 (unsigned long)(zone->end >> PAGE_CACHE_SHIFT), 304 zone); 305 306 if (ret == -EEXIST) { 307 kfree(zone); 308 ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone, 309 logical >> PAGE_CACHE_SHIFT, 1); 310 if (ret == 1) 311 kref_get(&zone->refcnt); 312 } 313 spin_unlock(&fs_info->reada_lock); 314 315 return zone; 316} 317 318static struct reada_extent *reada_find_extent(struct btrfs_root *root, 319 u64 logical, 320 struct btrfs_key *top, int level) 321{ 322 int ret; 323 struct reada_extent *re = NULL; 324 struct reada_extent *re_exist = NULL; 325 struct btrfs_fs_info *fs_info = root->fs_info; 326 struct btrfs_bio *bbio = NULL; 327 struct btrfs_device *dev; 328 struct btrfs_device *prev_dev; 329 u32 blocksize; 330 u64 length; 331 int nzones = 0; 332 int i; 333 unsigned long index = logical >> PAGE_CACHE_SHIFT; 334 int dev_replace_is_ongoing; 335 336 spin_lock(&fs_info->reada_lock); 337 re = radix_tree_lookup(&fs_info->reada_tree, index); 338 if (re) 339 re->refcnt++; 340 spin_unlock(&fs_info->reada_lock); 341 342 if (re) 343 return re; 344 345 re = kzalloc(sizeof(*re), GFP_NOFS); 346 if (!re) 347 return NULL; 348 349 blocksize = root->nodesize; 350 re->logical = logical; 351 re->top = *top; 352 INIT_LIST_HEAD(&re->extctl); 353 spin_lock_init(&re->lock); 354 re->refcnt = 1; 355 356 /* 357 * map block 358 */ 359 length = blocksize; 360 ret = btrfs_map_block(fs_info, REQ_GET_READ_MIRRORS, logical, &length, 361 &bbio, 0); 362 if (ret || !bbio || length < blocksize) 363 goto error; 364 365 if (bbio->num_stripes > BTRFS_MAX_MIRRORS) { 366 btrfs_err(root->fs_info, 367 "readahead: more than %d copies not supported", 368 BTRFS_MAX_MIRRORS); 369 goto error; 370 } 371 372 for (nzones = 0; nzones < bbio->num_stripes; ++nzones) { 373 struct reada_zone *zone; 374 375 dev = bbio->stripes[nzones].dev; 376 zone = reada_find_zone(fs_info, dev, logical, bbio); 377 if (!zone) 378 break; 379 380 re->zones[nzones] = zone; 381 spin_lock(&zone->lock); 382 if (!zone->elems) 383 kref_get(&zone->refcnt); 384 ++zone->elems; 385 spin_unlock(&zone->lock); 386 spin_lock(&fs_info->reada_lock); 387 kref_put(&zone->refcnt, reada_zone_release); 388 spin_unlock(&fs_info->reada_lock); 389 } 390 re->nzones = nzones; 391 if (nzones == 0) { 392 /* not a single zone found, error and out */ 393 goto error; 394 } 395 396 /* insert extent in reada_tree + all per-device trees, all or nothing */ 397 btrfs_dev_replace_lock(&fs_info->dev_replace); 398 spin_lock(&fs_info->reada_lock); 399 ret = radix_tree_insert(&fs_info->reada_tree, index, re); 400 if (ret == -EEXIST) { 401 re_exist = radix_tree_lookup(&fs_info->reada_tree, index); 402 BUG_ON(!re_exist); 403 re_exist->refcnt++; 404 spin_unlock(&fs_info->reada_lock); 405 btrfs_dev_replace_unlock(&fs_info->dev_replace); 406 goto error; 407 } 408 if (ret) { 409 spin_unlock(&fs_info->reada_lock); 410 btrfs_dev_replace_unlock(&fs_info->dev_replace); 411 goto error; 412 } 413 prev_dev = NULL; 414 dev_replace_is_ongoing = btrfs_dev_replace_is_ongoing( 415 &fs_info->dev_replace); 416 for (i = 0; i < nzones; ++i) { 417 dev = bbio->stripes[i].dev; 418 if (dev == prev_dev) { 419 /* 420 * in case of DUP, just add the first zone. As both 421 * are on the same device, there's nothing to gain 422 * from adding both. 423 * Also, it wouldn't work, as the tree is per device 424 * and adding would fail with EEXIST 425 */ 426 continue; 427 } 428 if (!dev->bdev) { 429 /* 430 * cannot read ahead on missing device, but for RAID5/6, 431 * REQ_GET_READ_MIRRORS return 1. So don't skip missing 432 * device for such case. 433 */ 434 if (nzones > 1) 435 continue; 436 } 437 if (dev_replace_is_ongoing && 438 dev == fs_info->dev_replace.tgtdev) { 439 /* 440 * as this device is selected for reading only as 441 * a last resort, skip it for read ahead. 442 */ 443 continue; 444 } 445 prev_dev = dev; 446 ret = radix_tree_insert(&dev->reada_extents, index, re); 447 if (ret) { 448 while (--i >= 0) { 449 dev = bbio->stripes[i].dev; 450 BUG_ON(dev == NULL); 451 /* ignore whether the entry was inserted */ 452 radix_tree_delete(&dev->reada_extents, index); 453 } 454 BUG_ON(fs_info == NULL); 455 radix_tree_delete(&fs_info->reada_tree, index); 456 spin_unlock(&fs_info->reada_lock); 457 btrfs_dev_replace_unlock(&fs_info->dev_replace); 458 goto error; 459 } 460 } 461 spin_unlock(&fs_info->reada_lock); 462 btrfs_dev_replace_unlock(&fs_info->dev_replace); 463 464 btrfs_put_bbio(bbio); 465 return re; 466 467error: 468 while (nzones) { 469 struct reada_zone *zone; 470 471 --nzones; 472 zone = re->zones[nzones]; 473 kref_get(&zone->refcnt); 474 spin_lock(&zone->lock); 475 --zone->elems; 476 if (zone->elems == 0) { 477 /* 478 * no fs_info->reada_lock needed, as this can't be 479 * the last ref 480 */ 481 kref_put(&zone->refcnt, reada_zone_release); 482 } 483 spin_unlock(&zone->lock); 484 485 spin_lock(&fs_info->reada_lock); 486 kref_put(&zone->refcnt, reada_zone_release); 487 spin_unlock(&fs_info->reada_lock); 488 } 489 btrfs_put_bbio(bbio); 490 kfree(re); 491 return re_exist; 492} 493 494static void reada_extent_put(struct btrfs_fs_info *fs_info, 495 struct reada_extent *re) 496{ 497 int i; 498 unsigned long index = re->logical >> PAGE_CACHE_SHIFT; 499 500 spin_lock(&fs_info->reada_lock); 501 if (--re->refcnt) { 502 spin_unlock(&fs_info->reada_lock); 503 return; 504 } 505 506 radix_tree_delete(&fs_info->reada_tree, index); 507 for (i = 0; i < re->nzones; ++i) { 508 struct reada_zone *zone = re->zones[i]; 509 510 radix_tree_delete(&zone->device->reada_extents, index); 511 } 512 513 spin_unlock(&fs_info->reada_lock); 514 515 for (i = 0; i < re->nzones; ++i) { 516 struct reada_zone *zone = re->zones[i]; 517 518 kref_get(&zone->refcnt); 519 spin_lock(&zone->lock); 520 --zone->elems; 521 if (zone->elems == 0) { 522 /* no fs_info->reada_lock needed, as this can't be 523 * the last ref */ 524 kref_put(&zone->refcnt, reada_zone_release); 525 } 526 spin_unlock(&zone->lock); 527 528 spin_lock(&fs_info->reada_lock); 529 kref_put(&zone->refcnt, reada_zone_release); 530 spin_unlock(&fs_info->reada_lock); 531 } 532 if (re->scheduled_for) 533 atomic_dec(&re->scheduled_for->reada_in_flight); 534 535 kfree(re); 536} 537 538static void reada_zone_release(struct kref *kref) 539{ 540 struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt); 541 542 radix_tree_delete(&zone->device->reada_zones, 543 zone->end >> PAGE_CACHE_SHIFT); 544 545 kfree(zone); 546} 547 548static void reada_control_release(struct kref *kref) 549{ 550 struct reada_control *rc = container_of(kref, struct reada_control, 551 refcnt); 552 553 kfree(rc); 554} 555 556static int reada_add_block(struct reada_control *rc, u64 logical, 557 struct btrfs_key *top, int level, u64 generation) 558{ 559 struct btrfs_root *root = rc->root; 560 struct reada_extent *re; 561 struct reada_extctl *rec; 562 563 re = reada_find_extent(root, logical, top, level); /* takes one ref */ 564 if (!re) 565 return -1; 566 567 rec = kzalloc(sizeof(*rec), GFP_NOFS); 568 if (!rec) { 569 reada_extent_put(root->fs_info, re); 570 return -1; 571 } 572 573 rec->rc = rc; 574 rec->generation = generation; 575 atomic_inc(&rc->elems); 576 577 spin_lock(&re->lock); 578 list_add_tail(&rec->list, &re->extctl); 579 spin_unlock(&re->lock); 580 581 /* leave the ref on the extent */ 582 583 return 0; 584} 585 586/* 587 * called with fs_info->reada_lock held 588 */ 589static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock) 590{ 591 int i; 592 unsigned long index = zone->end >> PAGE_CACHE_SHIFT; 593 594 for (i = 0; i < zone->ndevs; ++i) { 595 struct reada_zone *peer; 596 peer = radix_tree_lookup(&zone->devs[i]->reada_zones, index); 597 if (peer && peer->device != zone->device) 598 peer->locked = lock; 599 } 600} 601 602/* 603 * called with fs_info->reada_lock held 604 */ 605static int reada_pick_zone(struct btrfs_device *dev) 606{ 607 struct reada_zone *top_zone = NULL; 608 struct reada_zone *top_locked_zone = NULL; 609 u64 top_elems = 0; 610 u64 top_locked_elems = 0; 611 unsigned long index = 0; 612 int ret; 613 614 if (dev->reada_curr_zone) { 615 reada_peer_zones_set_lock(dev->reada_curr_zone, 0); 616 kref_put(&dev->reada_curr_zone->refcnt, reada_zone_release); 617 dev->reada_curr_zone = NULL; 618 } 619 /* pick the zone with the most elements */ 620 while (1) { 621 struct reada_zone *zone; 622 623 ret = radix_tree_gang_lookup(&dev->reada_zones, 624 (void **)&zone, index, 1); 625 if (ret == 0) 626 break; 627 index = (zone->end >> PAGE_CACHE_SHIFT) + 1; 628 if (zone->locked) { 629 if (zone->elems > top_locked_elems) { 630 top_locked_elems = zone->elems; 631 top_locked_zone = zone; 632 } 633 } else { 634 if (zone->elems > top_elems) { 635 top_elems = zone->elems; 636 top_zone = zone; 637 } 638 } 639 } 640 if (top_zone) 641 dev->reada_curr_zone = top_zone; 642 else if (top_locked_zone) 643 dev->reada_curr_zone = top_locked_zone; 644 else 645 return 0; 646 647 dev->reada_next = dev->reada_curr_zone->start; 648 kref_get(&dev->reada_curr_zone->refcnt); 649 reada_peer_zones_set_lock(dev->reada_curr_zone, 1); 650 651 return 1; 652} 653 654static int reada_start_machine_dev(struct btrfs_fs_info *fs_info, 655 struct btrfs_device *dev) 656{ 657 struct reada_extent *re = NULL; 658 int mirror_num = 0; 659 struct extent_buffer *eb = NULL; 660 u64 logical; 661 int ret; 662 int i; 663 int need_kick = 0; 664 665 spin_lock(&fs_info->reada_lock); 666 if (dev->reada_curr_zone == NULL) { 667 ret = reada_pick_zone(dev); 668 if (!ret) { 669 spin_unlock(&fs_info->reada_lock); 670 return 0; 671 } 672 } 673 /* 674 * FIXME currently we issue the reads one extent at a time. If we have 675 * a contiguous block of extents, we could also coagulate them or use 676 * plugging to speed things up 677 */ 678 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re, 679 dev->reada_next >> PAGE_CACHE_SHIFT, 1); 680 if (ret == 0 || re->logical >= dev->reada_curr_zone->end) { 681 ret = reada_pick_zone(dev); 682 if (!ret) { 683 spin_unlock(&fs_info->reada_lock); 684 return 0; 685 } 686 re = NULL; 687 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re, 688 dev->reada_next >> PAGE_CACHE_SHIFT, 1); 689 } 690 if (ret == 0) { 691 spin_unlock(&fs_info->reada_lock); 692 return 0; 693 } 694 dev->reada_next = re->logical + fs_info->tree_root->nodesize; 695 re->refcnt++; 696 697 spin_unlock(&fs_info->reada_lock); 698 699 /* 700 * find mirror num 701 */ 702 for (i = 0; i < re->nzones; ++i) { 703 if (re->zones[i]->device == dev) { 704 mirror_num = i + 1; 705 break; 706 } 707 } 708 logical = re->logical; 709 710 spin_lock(&re->lock); 711 if (re->scheduled_for == NULL) { 712 re->scheduled_for = dev; 713 need_kick = 1; 714 } 715 spin_unlock(&re->lock); 716 717 reada_extent_put(fs_info, re); 718 719 if (!need_kick) 720 return 0; 721 722 atomic_inc(&dev->reada_in_flight); 723 ret = reada_tree_block_flagged(fs_info->extent_root, logical, 724 mirror_num, &eb); 725 if (ret) 726 __readahead_hook(fs_info->extent_root, NULL, logical, ret); 727 else if (eb) 728 __readahead_hook(fs_info->extent_root, eb, eb->start, ret); 729 730 if (eb) 731 free_extent_buffer(eb); 732 733 return 1; 734 735} 736 737static void reada_start_machine_worker(struct btrfs_work *work) 738{ 739 struct reada_machine_work *rmw; 740 struct btrfs_fs_info *fs_info; 741 int old_ioprio; 742 743 rmw = container_of(work, struct reada_machine_work, work); 744 fs_info = rmw->fs_info; 745 746 kfree(rmw); 747 748 old_ioprio = IOPRIO_PRIO_VALUE(task_nice_ioclass(current), 749 task_nice_ioprio(current)); 750 set_task_ioprio(current, BTRFS_IOPRIO_READA); 751 __reada_start_machine(fs_info); 752 set_task_ioprio(current, old_ioprio); 753} 754 755static void __reada_start_machine(struct btrfs_fs_info *fs_info) 756{ 757 struct btrfs_device *device; 758 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices; 759 u64 enqueued; 760 u64 total = 0; 761 int i; 762 763 do { 764 enqueued = 0; 765 list_for_each_entry(device, &fs_devices->devices, dev_list) { 766 if (atomic_read(&device->reada_in_flight) < 767 MAX_IN_FLIGHT) 768 enqueued += reada_start_machine_dev(fs_info, 769 device); 770 } 771 total += enqueued; 772 } while (enqueued && total < 10000); 773 774 if (enqueued == 0) 775 return; 776 777 /* 778 * If everything is already in the cache, this is effectively single 779 * threaded. To a) not hold the caller for too long and b) to utilize 780 * more cores, we broke the loop above after 10000 iterations and now 781 * enqueue to workers to finish it. This will distribute the load to 782 * the cores. 783 */ 784 for (i = 0; i < 2; ++i) 785 reada_start_machine(fs_info); 786} 787 788static void reada_start_machine(struct btrfs_fs_info *fs_info) 789{ 790 struct reada_machine_work *rmw; 791 792 rmw = kzalloc(sizeof(*rmw), GFP_NOFS); 793 if (!rmw) { 794 /* FIXME we cannot handle this properly right now */ 795 BUG(); 796 } 797 btrfs_init_work(&rmw->work, btrfs_readahead_helper, 798 reada_start_machine_worker, NULL, NULL); 799 rmw->fs_info = fs_info; 800 801 btrfs_queue_work(fs_info->readahead_workers, &rmw->work); 802} 803 804#ifdef DEBUG 805static void dump_devs(struct btrfs_fs_info *fs_info, int all) 806{ 807 struct btrfs_device *device; 808 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices; 809 unsigned long index; 810 int ret; 811 int i; 812 int j; 813 int cnt; 814 815 spin_lock(&fs_info->reada_lock); 816 list_for_each_entry(device, &fs_devices->devices, dev_list) { 817 printk(KERN_DEBUG "dev %lld has %d in flight\n", device->devid, 818 atomic_read(&device->reada_in_flight)); 819 index = 0; 820 while (1) { 821 struct reada_zone *zone; 822 ret = radix_tree_gang_lookup(&device->reada_zones, 823 (void **)&zone, index, 1); 824 if (ret == 0) 825 break; 826 printk(KERN_DEBUG " zone %llu-%llu elems %llu locked " 827 "%d devs", zone->start, zone->end, zone->elems, 828 zone->locked); 829 for (j = 0; j < zone->ndevs; ++j) { 830 printk(KERN_CONT " %lld", 831 zone->devs[j]->devid); 832 } 833 if (device->reada_curr_zone == zone) 834 printk(KERN_CONT " curr off %llu", 835 device->reada_next - zone->start); 836 printk(KERN_CONT "\n"); 837 index = (zone->end >> PAGE_CACHE_SHIFT) + 1; 838 } 839 cnt = 0; 840 index = 0; 841 while (all) { 842 struct reada_extent *re = NULL; 843 844 ret = radix_tree_gang_lookup(&device->reada_extents, 845 (void **)&re, index, 1); 846 if (ret == 0) 847 break; 848 printk(KERN_DEBUG 849 " re: logical %llu size %u empty %d for %lld", 850 re->logical, fs_info->tree_root->nodesize, 851 list_empty(&re->extctl), re->scheduled_for ? 852 re->scheduled_for->devid : -1); 853 854 for (i = 0; i < re->nzones; ++i) { 855 printk(KERN_CONT " zone %llu-%llu devs", 856 re->zones[i]->start, 857 re->zones[i]->end); 858 for (j = 0; j < re->zones[i]->ndevs; ++j) { 859 printk(KERN_CONT " %lld", 860 re->zones[i]->devs[j]->devid); 861 } 862 } 863 printk(KERN_CONT "\n"); 864 index = (re->logical >> PAGE_CACHE_SHIFT) + 1; 865 if (++cnt > 15) 866 break; 867 } 868 } 869 870 index = 0; 871 cnt = 0; 872 while (all) { 873 struct reada_extent *re = NULL; 874 875 ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re, 876 index, 1); 877 if (ret == 0) 878 break; 879 if (!re->scheduled_for) { 880 index = (re->logical >> PAGE_CACHE_SHIFT) + 1; 881 continue; 882 } 883 printk(KERN_DEBUG 884 "re: logical %llu size %u list empty %d for %lld", 885 re->logical, fs_info->tree_root->nodesize, 886 list_empty(&re->extctl), 887 re->scheduled_for ? re->scheduled_for->devid : -1); 888 for (i = 0; i < re->nzones; ++i) { 889 printk(KERN_CONT " zone %llu-%llu devs", 890 re->zones[i]->start, 891 re->zones[i]->end); 892 for (i = 0; i < re->nzones; ++i) { 893 printk(KERN_CONT " zone %llu-%llu devs", 894 re->zones[i]->start, 895 re->zones[i]->end); 896 for (j = 0; j < re->zones[i]->ndevs; ++j) { 897 printk(KERN_CONT " %lld", 898 re->zones[i]->devs[j]->devid); 899 } 900 } 901 } 902 printk(KERN_CONT "\n"); 903 index = (re->logical >> PAGE_CACHE_SHIFT) + 1; 904 } 905 spin_unlock(&fs_info->reada_lock); 906} 907#endif 908 909/* 910 * interface 911 */ 912struct reada_control *btrfs_reada_add(struct btrfs_root *root, 913 struct btrfs_key *key_start, struct btrfs_key *key_end) 914{ 915 struct reada_control *rc; 916 u64 start; 917 u64 generation; 918 int level; 919 struct extent_buffer *node; 920 static struct btrfs_key max_key = { 921 .objectid = (u64)-1, 922 .type = (u8)-1, 923 .offset = (u64)-1 924 }; 925 926 rc = kzalloc(sizeof(*rc), GFP_NOFS); 927 if (!rc) 928 return ERR_PTR(-ENOMEM); 929 930 rc->root = root; 931 rc->key_start = *key_start; 932 rc->key_end = *key_end; 933 atomic_set(&rc->elems, 0); 934 init_waitqueue_head(&rc->wait); 935 kref_init(&rc->refcnt); 936 kref_get(&rc->refcnt); /* one ref for having elements */ 937 938 node = btrfs_root_node(root); 939 start = node->start; 940 level = btrfs_header_level(node); 941 generation = btrfs_header_generation(node); 942 free_extent_buffer(node); 943 944 if (reada_add_block(rc, start, &max_key, level, generation)) { 945 kfree(rc); 946 return ERR_PTR(-ENOMEM); 947 } 948 949 reada_start_machine(root->fs_info); 950 951 return rc; 952} 953 954#ifdef DEBUG 955int btrfs_reada_wait(void *handle) 956{ 957 struct reada_control *rc = handle; 958 959 while (atomic_read(&rc->elems)) { 960 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0, 961 5 * HZ); 962 dump_devs(rc->root->fs_info, 963 atomic_read(&rc->elems) < 10 ? 1 : 0); 964 } 965 966 dump_devs(rc->root->fs_info, atomic_read(&rc->elems) < 10 ? 1 : 0); 967 968 kref_put(&rc->refcnt, reada_control_release); 969 970 return 0; 971} 972#else 973int btrfs_reada_wait(void *handle) 974{ 975 struct reada_control *rc = handle; 976 977 while (atomic_read(&rc->elems)) { 978 wait_event(rc->wait, atomic_read(&rc->elems) == 0); 979 } 980 981 kref_put(&rc->refcnt, reada_control_release); 982 983 return 0; 984} 985#endif 986 987void btrfs_reada_detach(void *handle) 988{ 989 struct reada_control *rc = handle; 990 991 kref_put(&rc->refcnt, reada_control_release); 992} 993