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