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 real_stripes; 332 int nzones = 0; 333 int i; 334 unsigned long index = logical >> PAGE_CACHE_SHIFT; 335 int dev_replace_is_ongoing; 336 337 spin_lock(&fs_info->reada_lock); 338 re = radix_tree_lookup(&fs_info->reada_tree, index); 339 if (re) 340 re->refcnt++; 341 spin_unlock(&fs_info->reada_lock); 342 343 if (re) 344 return re; 345 346 re = kzalloc(sizeof(*re), GFP_NOFS); 347 if (!re) 348 return NULL; 349 350 blocksize = root->nodesize; 351 re->logical = logical; 352 re->top = *top; 353 INIT_LIST_HEAD(&re->extctl); 354 spin_lock_init(&re->lock); 355 re->refcnt = 1; 356 357 /* 358 * map block 359 */ 360 length = blocksize; 361 ret = btrfs_map_block(fs_info, REQ_GET_READ_MIRRORS, logical, &length, 362 &bbio, 0); 363 if (ret || !bbio || length < blocksize) 364 goto error; 365 366 if (bbio->num_stripes > BTRFS_MAX_MIRRORS) { 367 btrfs_err(root->fs_info, 368 "readahead: more than %d copies not supported", 369 BTRFS_MAX_MIRRORS); 370 goto error; 371 } 372 373 real_stripes = bbio->num_stripes - bbio->num_tgtdevs; 374 for (nzones = 0; nzones < real_stripes; ++nzones) { 375 struct reada_zone *zone; 376 377 dev = bbio->stripes[nzones].dev; 378 zone = reada_find_zone(fs_info, dev, logical, bbio); 379 if (!zone) 380 break; 381 382 re->zones[nzones] = zone; 383 spin_lock(&zone->lock); 384 if (!zone->elems) 385 kref_get(&zone->refcnt); 386 ++zone->elems; 387 spin_unlock(&zone->lock); 388 spin_lock(&fs_info->reada_lock); 389 kref_put(&zone->refcnt, reada_zone_release); 390 spin_unlock(&fs_info->reada_lock); 391 } 392 re->nzones = nzones; 393 if (nzones == 0) { 394 /* not a single zone found, error and out */ 395 goto error; 396 } 397 398 /* insert extent in reada_tree + all per-device trees, all or nothing */ 399 btrfs_dev_replace_lock(&fs_info->dev_replace); 400 spin_lock(&fs_info->reada_lock); 401 ret = radix_tree_insert(&fs_info->reada_tree, index, re); 402 if (ret == -EEXIST) { 403 re_exist = radix_tree_lookup(&fs_info->reada_tree, index); 404 BUG_ON(!re_exist); 405 re_exist->refcnt++; 406 spin_unlock(&fs_info->reada_lock); 407 btrfs_dev_replace_unlock(&fs_info->dev_replace); 408 goto error; 409 } 410 if (ret) { 411 spin_unlock(&fs_info->reada_lock); 412 btrfs_dev_replace_unlock(&fs_info->dev_replace); 413 goto error; 414 } 415 prev_dev = NULL; 416 dev_replace_is_ongoing = btrfs_dev_replace_is_ongoing( 417 &fs_info->dev_replace); 418 for (i = 0; i < nzones; ++i) { 419 dev = bbio->stripes[i].dev; 420 if (dev == prev_dev) { 421 /* 422 * in case of DUP, just add the first zone. As both 423 * are on the same device, there's nothing to gain 424 * from adding both. 425 * Also, it wouldn't work, as the tree is per device 426 * and adding would fail with EEXIST 427 */ 428 continue; 429 } 430 if (!dev->bdev) { 431 /* 432 * cannot read ahead on missing device, but for RAID5/6, 433 * REQ_GET_READ_MIRRORS return 1. So don't skip missing 434 * device for such case. 435 */ 436 if (nzones > 1) 437 continue; 438 } 439 if (dev_replace_is_ongoing && 440 dev == fs_info->dev_replace.tgtdev) { 441 /* 442 * as this device is selected for reading only as 443 * a last resort, skip it for read ahead. 444 */ 445 continue; 446 } 447 prev_dev = dev; 448 ret = radix_tree_insert(&dev->reada_extents, index, re); 449 if (ret) { 450 while (--i >= 0) { 451 dev = bbio->stripes[i].dev; 452 BUG_ON(dev == NULL); 453 /* ignore whether the entry was inserted */ 454 radix_tree_delete(&dev->reada_extents, index); 455 } 456 BUG_ON(fs_info == NULL); 457 radix_tree_delete(&fs_info->reada_tree, index); 458 spin_unlock(&fs_info->reada_lock); 459 btrfs_dev_replace_unlock(&fs_info->dev_replace); 460 goto error; 461 } 462 } 463 spin_unlock(&fs_info->reada_lock); 464 btrfs_dev_replace_unlock(&fs_info->dev_replace); 465 466 btrfs_put_bbio(bbio); 467 return re; 468 469error: 470 while (nzones) { 471 struct reada_zone *zone; 472 473 --nzones; 474 zone = re->zones[nzones]; 475 kref_get(&zone->refcnt); 476 spin_lock(&zone->lock); 477 --zone->elems; 478 if (zone->elems == 0) { 479 /* 480 * no fs_info->reada_lock needed, as this can't be 481 * the last ref 482 */ 483 kref_put(&zone->refcnt, reada_zone_release); 484 } 485 spin_unlock(&zone->lock); 486 487 spin_lock(&fs_info->reada_lock); 488 kref_put(&zone->refcnt, reada_zone_release); 489 spin_unlock(&fs_info->reada_lock); 490 } 491 btrfs_put_bbio(bbio); 492 kfree(re); 493 return re_exist; 494} 495 496static void reada_extent_put(struct btrfs_fs_info *fs_info, 497 struct reada_extent *re) 498{ 499 int i; 500 unsigned long index = re->logical >> PAGE_CACHE_SHIFT; 501 502 spin_lock(&fs_info->reada_lock); 503 if (--re->refcnt) { 504 spin_unlock(&fs_info->reada_lock); 505 return; 506 } 507 508 radix_tree_delete(&fs_info->reada_tree, index); 509 for (i = 0; i < re->nzones; ++i) { 510 struct reada_zone *zone = re->zones[i]; 511 512 radix_tree_delete(&zone->device->reada_extents, index); 513 } 514 515 spin_unlock(&fs_info->reada_lock); 516 517 for (i = 0; i < re->nzones; ++i) { 518 struct reada_zone *zone = re->zones[i]; 519 520 kref_get(&zone->refcnt); 521 spin_lock(&zone->lock); 522 --zone->elems; 523 if (zone->elems == 0) { 524 /* no fs_info->reada_lock needed, as this can't be 525 * the last ref */ 526 kref_put(&zone->refcnt, reada_zone_release); 527 } 528 spin_unlock(&zone->lock); 529 530 spin_lock(&fs_info->reada_lock); 531 kref_put(&zone->refcnt, reada_zone_release); 532 spin_unlock(&fs_info->reada_lock); 533 } 534 if (re->scheduled_for) 535 atomic_dec(&re->scheduled_for->reada_in_flight); 536 537 kfree(re); 538} 539 540static void reada_zone_release(struct kref *kref) 541{ 542 struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt); 543 544 radix_tree_delete(&zone->device->reada_zones, 545 zone->end >> PAGE_CACHE_SHIFT); 546 547 kfree(zone); 548} 549 550static void reada_control_release(struct kref *kref) 551{ 552 struct reada_control *rc = container_of(kref, struct reada_control, 553 refcnt); 554 555 kfree(rc); 556} 557 558static int reada_add_block(struct reada_control *rc, u64 logical, 559 struct btrfs_key *top, int level, u64 generation) 560{ 561 struct btrfs_root *root = rc->root; 562 struct reada_extent *re; 563 struct reada_extctl *rec; 564 565 re = reada_find_extent(root, logical, top, level); /* takes one ref */ 566 if (!re) 567 return -1; 568 569 rec = kzalloc(sizeof(*rec), GFP_NOFS); 570 if (!rec) { 571 reada_extent_put(root->fs_info, re); 572 return -ENOMEM; 573 } 574 575 rec->rc = rc; 576 rec->generation = generation; 577 atomic_inc(&rc->elems); 578 579 spin_lock(&re->lock); 580 list_add_tail(&rec->list, &re->extctl); 581 spin_unlock(&re->lock); 582 583 /* leave the ref on the extent */ 584 585 return 0; 586} 587 588/* 589 * called with fs_info->reada_lock held 590 */ 591static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock) 592{ 593 int i; 594 unsigned long index = zone->end >> PAGE_CACHE_SHIFT; 595 596 for (i = 0; i < zone->ndevs; ++i) { 597 struct reada_zone *peer; 598 peer = radix_tree_lookup(&zone->devs[i]->reada_zones, index); 599 if (peer && peer->device != zone->device) 600 peer->locked = lock; 601 } 602} 603 604/* 605 * called with fs_info->reada_lock held 606 */ 607static int reada_pick_zone(struct btrfs_device *dev) 608{ 609 struct reada_zone *top_zone = NULL; 610 struct reada_zone *top_locked_zone = NULL; 611 u64 top_elems = 0; 612 u64 top_locked_elems = 0; 613 unsigned long index = 0; 614 int ret; 615 616 if (dev->reada_curr_zone) { 617 reada_peer_zones_set_lock(dev->reada_curr_zone, 0); 618 kref_put(&dev->reada_curr_zone->refcnt, reada_zone_release); 619 dev->reada_curr_zone = NULL; 620 } 621 /* pick the zone with the most elements */ 622 while (1) { 623 struct reada_zone *zone; 624 625 ret = radix_tree_gang_lookup(&dev->reada_zones, 626 (void **)&zone, index, 1); 627 if (ret == 0) 628 break; 629 index = (zone->end >> PAGE_CACHE_SHIFT) + 1; 630 if (zone->locked) { 631 if (zone->elems > top_locked_elems) { 632 top_locked_elems = zone->elems; 633 top_locked_zone = zone; 634 } 635 } else { 636 if (zone->elems > top_elems) { 637 top_elems = zone->elems; 638 top_zone = zone; 639 } 640 } 641 } 642 if (top_zone) 643 dev->reada_curr_zone = top_zone; 644 else if (top_locked_zone) 645 dev->reada_curr_zone = top_locked_zone; 646 else 647 return 0; 648 649 dev->reada_next = dev->reada_curr_zone->start; 650 kref_get(&dev->reada_curr_zone->refcnt); 651 reada_peer_zones_set_lock(dev->reada_curr_zone, 1); 652 653 return 1; 654} 655 656static int reada_start_machine_dev(struct btrfs_fs_info *fs_info, 657 struct btrfs_device *dev) 658{ 659 struct reada_extent *re = NULL; 660 int mirror_num = 0; 661 struct extent_buffer *eb = NULL; 662 u64 logical; 663 int ret; 664 int i; 665 int need_kick = 0; 666 667 spin_lock(&fs_info->reada_lock); 668 if (dev->reada_curr_zone == NULL) { 669 ret = reada_pick_zone(dev); 670 if (!ret) { 671 spin_unlock(&fs_info->reada_lock); 672 return 0; 673 } 674 } 675 /* 676 * FIXME currently we issue the reads one extent at a time. If we have 677 * a contiguous block of extents, we could also coagulate them or use 678 * plugging to speed things up 679 */ 680 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re, 681 dev->reada_next >> PAGE_CACHE_SHIFT, 1); 682 if (ret == 0 || re->logical >= dev->reada_curr_zone->end) { 683 ret = reada_pick_zone(dev); 684 if (!ret) { 685 spin_unlock(&fs_info->reada_lock); 686 return 0; 687 } 688 re = NULL; 689 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re, 690 dev->reada_next >> PAGE_CACHE_SHIFT, 1); 691 } 692 if (ret == 0) { 693 spin_unlock(&fs_info->reada_lock); 694 return 0; 695 } 696 dev->reada_next = re->logical + fs_info->tree_root->nodesize; 697 re->refcnt++; 698 699 spin_unlock(&fs_info->reada_lock); 700 701 /* 702 * find mirror num 703 */ 704 for (i = 0; i < re->nzones; ++i) { 705 if (re->zones[i]->device == dev) { 706 mirror_num = i + 1; 707 break; 708 } 709 } 710 logical = re->logical; 711 712 spin_lock(&re->lock); 713 if (re->scheduled_for == NULL) { 714 re->scheduled_for = dev; 715 need_kick = 1; 716 } 717 spin_unlock(&re->lock); 718 719 reada_extent_put(fs_info, re); 720 721 if (!need_kick) 722 return 0; 723 724 atomic_inc(&dev->reada_in_flight); 725 ret = reada_tree_block_flagged(fs_info->extent_root, logical, 726 mirror_num, &eb); 727 if (ret) 728 __readahead_hook(fs_info->extent_root, NULL, logical, ret); 729 else if (eb) 730 __readahead_hook(fs_info->extent_root, eb, eb->start, ret); 731 732 if (eb) 733 free_extent_buffer(eb); 734 735 return 1; 736 737} 738 739static void reada_start_machine_worker(struct btrfs_work *work) 740{ 741 struct reada_machine_work *rmw; 742 struct btrfs_fs_info *fs_info; 743 int old_ioprio; 744 745 rmw = container_of(work, struct reada_machine_work, work); 746 fs_info = rmw->fs_info; 747 748 kfree(rmw); 749 750 old_ioprio = IOPRIO_PRIO_VALUE(task_nice_ioclass(current), 751 task_nice_ioprio(current)); 752 set_task_ioprio(current, BTRFS_IOPRIO_READA); 753 __reada_start_machine(fs_info); 754 set_task_ioprio(current, old_ioprio); 755} 756 757static void __reada_start_machine(struct btrfs_fs_info *fs_info) 758{ 759 struct btrfs_device *device; 760 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices; 761 u64 enqueued; 762 u64 total = 0; 763 int i; 764 765 do { 766 enqueued = 0; 767 list_for_each_entry(device, &fs_devices->devices, dev_list) { 768 if (atomic_read(&device->reada_in_flight) < 769 MAX_IN_FLIGHT) 770 enqueued += reada_start_machine_dev(fs_info, 771 device); 772 } 773 total += enqueued; 774 } while (enqueued && total < 10000); 775 776 if (enqueued == 0) 777 return; 778 779 /* 780 * If everything is already in the cache, this is effectively single 781 * threaded. To a) not hold the caller for too long and b) to utilize 782 * more cores, we broke the loop above after 10000 iterations and now 783 * enqueue to workers to finish it. This will distribute the load to 784 * the cores. 785 */ 786 for (i = 0; i < 2; ++i) 787 reada_start_machine(fs_info); 788} 789 790static void reada_start_machine(struct btrfs_fs_info *fs_info) 791{ 792 struct reada_machine_work *rmw; 793 794 rmw = kzalloc(sizeof(*rmw), GFP_NOFS); 795 if (!rmw) { 796 /* FIXME we cannot handle this properly right now */ 797 BUG(); 798 } 799 btrfs_init_work(&rmw->work, btrfs_readahead_helper, 800 reada_start_machine_worker, NULL, NULL); 801 rmw->fs_info = fs_info; 802 803 btrfs_queue_work(fs_info->readahead_workers, &rmw->work); 804} 805 806#ifdef DEBUG 807static void dump_devs(struct btrfs_fs_info *fs_info, int all) 808{ 809 struct btrfs_device *device; 810 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices; 811 unsigned long index; 812 int ret; 813 int i; 814 int j; 815 int cnt; 816 817 spin_lock(&fs_info->reada_lock); 818 list_for_each_entry(device, &fs_devices->devices, dev_list) { 819 printk(KERN_DEBUG "dev %lld has %d in flight\n", device->devid, 820 atomic_read(&device->reada_in_flight)); 821 index = 0; 822 while (1) { 823 struct reada_zone *zone; 824 ret = radix_tree_gang_lookup(&device->reada_zones, 825 (void **)&zone, index, 1); 826 if (ret == 0) 827 break; 828 printk(KERN_DEBUG " zone %llu-%llu elems %llu locked " 829 "%d devs", zone->start, zone->end, zone->elems, 830 zone->locked); 831 for (j = 0; j < zone->ndevs; ++j) { 832 printk(KERN_CONT " %lld", 833 zone->devs[j]->devid); 834 } 835 if (device->reada_curr_zone == zone) 836 printk(KERN_CONT " curr off %llu", 837 device->reada_next - zone->start); 838 printk(KERN_CONT "\n"); 839 index = (zone->end >> PAGE_CACHE_SHIFT) + 1; 840 } 841 cnt = 0; 842 index = 0; 843 while (all) { 844 struct reada_extent *re = NULL; 845 846 ret = radix_tree_gang_lookup(&device->reada_extents, 847 (void **)&re, index, 1); 848 if (ret == 0) 849 break; 850 printk(KERN_DEBUG 851 " re: logical %llu size %u empty %d for %lld", 852 re->logical, fs_info->tree_root->nodesize, 853 list_empty(&re->extctl), re->scheduled_for ? 854 re->scheduled_for->devid : -1); 855 856 for (i = 0; i < re->nzones; ++i) { 857 printk(KERN_CONT " zone %llu-%llu devs", 858 re->zones[i]->start, 859 re->zones[i]->end); 860 for (j = 0; j < re->zones[i]->ndevs; ++j) { 861 printk(KERN_CONT " %lld", 862 re->zones[i]->devs[j]->devid); 863 } 864 } 865 printk(KERN_CONT "\n"); 866 index = (re->logical >> PAGE_CACHE_SHIFT) + 1; 867 if (++cnt > 15) 868 break; 869 } 870 } 871 872 index = 0; 873 cnt = 0; 874 while (all) { 875 struct reada_extent *re = NULL; 876 877 ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re, 878 index, 1); 879 if (ret == 0) 880 break; 881 if (!re->scheduled_for) { 882 index = (re->logical >> PAGE_CACHE_SHIFT) + 1; 883 continue; 884 } 885 printk(KERN_DEBUG 886 "re: logical %llu size %u list empty %d for %lld", 887 re->logical, fs_info->tree_root->nodesize, 888 list_empty(&re->extctl), 889 re->scheduled_for ? re->scheduled_for->devid : -1); 890 for (i = 0; i < re->nzones; ++i) { 891 printk(KERN_CONT " zone %llu-%llu devs", 892 re->zones[i]->start, 893 re->zones[i]->end); 894 for (i = 0; i < re->nzones; ++i) { 895 printk(KERN_CONT " zone %llu-%llu devs", 896 re->zones[i]->start, 897 re->zones[i]->end); 898 for (j = 0; j < re->zones[i]->ndevs; ++j) { 899 printk(KERN_CONT " %lld", 900 re->zones[i]->devs[j]->devid); 901 } 902 } 903 } 904 printk(KERN_CONT "\n"); 905 index = (re->logical >> PAGE_CACHE_SHIFT) + 1; 906 } 907 spin_unlock(&fs_info->reada_lock); 908} 909#endif 910 911/* 912 * interface 913 */ 914struct reada_control *btrfs_reada_add(struct btrfs_root *root, 915 struct btrfs_key *key_start, struct btrfs_key *key_end) 916{ 917 struct reada_control *rc; 918 u64 start; 919 u64 generation; 920 int level; 921 int ret; 922 struct extent_buffer *node; 923 static struct btrfs_key max_key = { 924 .objectid = (u64)-1, 925 .type = (u8)-1, 926 .offset = (u64)-1 927 }; 928 929 rc = kzalloc(sizeof(*rc), GFP_NOFS); 930 if (!rc) 931 return ERR_PTR(-ENOMEM); 932 933 rc->root = root; 934 rc->key_start = *key_start; 935 rc->key_end = *key_end; 936 atomic_set(&rc->elems, 0); 937 init_waitqueue_head(&rc->wait); 938 kref_init(&rc->refcnt); 939 kref_get(&rc->refcnt); /* one ref for having elements */ 940 941 node = btrfs_root_node(root); 942 start = node->start; 943 level = btrfs_header_level(node); 944 generation = btrfs_header_generation(node); 945 free_extent_buffer(node); 946 947 ret = reada_add_block(rc, start, &max_key, level, generation); 948 if (ret) { 949 kfree(rc); 950 return ERR_PTR(ret); 951 } 952 953 reada_start_machine(root->fs_info); 954 955 return rc; 956} 957 958#ifdef DEBUG 959int btrfs_reada_wait(void *handle) 960{ 961 struct reada_control *rc = handle; 962 963 while (atomic_read(&rc->elems)) { 964 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0, 965 5 * HZ); 966 dump_devs(rc->root->fs_info, 967 atomic_read(&rc->elems) < 10 ? 1 : 0); 968 } 969 970 dump_devs(rc->root->fs_info, atomic_read(&rc->elems) < 10 ? 1 : 0); 971 972 kref_put(&rc->refcnt, reada_control_release); 973 974 return 0; 975} 976#else 977int btrfs_reada_wait(void *handle) 978{ 979 struct reada_control *rc = handle; 980 981 while (atomic_read(&rc->elems)) { 982 wait_event(rc->wait, atomic_read(&rc->elems) == 0); 983 } 984 985 kref_put(&rc->refcnt, reada_control_release); 986 987 return 0; 988} 989#endif 990 991void btrfs_reada_detach(void *handle) 992{ 993 struct reada_control *rc = handle; 994 995 kref_put(&rc->refcnt, reada_control_release); 996} 997