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Linux 4.19.133
[linux/fpc-iii.git] / fs / btrfs / reada.c
blob4c81ffe123857416a394959c20895172d7418f5a
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2011 STRATO. All rights reserved.
4 */
5
6 #include <linux/sched.h>
7 #include <linux/pagemap.h>
8 #include <linux/writeback.h>
9 #include <linux/blkdev.h>
10 #include <linux/slab.h>
11 #include <linux/workqueue.h>
12 #include "ctree.h"
13 #include "volumes.h"
14 #include "disk-io.h"
15 #include "transaction.h"
16 #include "dev-replace.h"
17
18 #undef DEBUG
19
20 /*
21 * This is the implementation for the generic read ahead framework.
22 *
23 * To trigger a readahead, btrfs_reada_add must be called. It will start
24 * a read ahead for the given range [start, end) on tree root. The returned
25 * handle can either be used to wait on the readahead to finish
26 * (btrfs_reada_wait), or to send it to the background (btrfs_reada_detach).
27 *
28 * The read ahead works as follows:
29 * On btrfs_reada_add, the root of the tree is inserted into a radix_tree.
30 * reada_start_machine will then search for extents to prefetch and trigger
31 * some reads. When a read finishes for a node, all contained node/leaf
32 * pointers that lie in the given range will also be enqueued. The reads will
33 * be triggered in sequential order, thus giving a big win over a naive
34 * enumeration. It will also make use of multi-device layouts. Each disk
35 * will have its on read pointer and all disks will by utilized in parallel.
36 * Also will no two disks read both sides of a mirror simultaneously, as this
37 * would waste seeking capacity. Instead both disks will read different parts
38 * of the filesystem.
39 * Any number of readaheads can be started in parallel. The read order will be
40 * determined globally, i.e. 2 parallel readaheads will normally finish faster
41 * than the 2 started one after another.
42 */
43
44 #define MAX_IN_FLIGHT 6
45
46 struct reada_extctl {
47 struct list_head list;
48 struct reada_control *rc;
49 u64 generation;
50 };
51
52 struct reada_extent {
53 u64 logical;
54 struct btrfs_key top;
55 struct list_head extctl;
56 int refcnt;
57 spinlock_t lock;
58 struct reada_zone *zones[BTRFS_MAX_MIRRORS];
59 int nzones;
60 int scheduled;
61 };
62
63 struct reada_zone {
64 u64 start;
65 u64 end;
66 u64 elems;
67 struct list_head list;
68 spinlock_t lock;
69 int locked;
70 struct btrfs_device *device;
71 struct btrfs_device *devs[BTRFS_MAX_MIRRORS]; /* full list, incl
72 * self */
73 int ndevs;
74 struct kref refcnt;
75 };
76
77 struct reada_machine_work {
78 struct btrfs_work work;
79 struct btrfs_fs_info *fs_info;
80 };
81
82 static void reada_extent_put(struct btrfs_fs_info *, struct reada_extent *);
83 static void reada_control_release(struct kref *kref);
84 static void reada_zone_release(struct kref *kref);
85 static void reada_start_machine(struct btrfs_fs_info *fs_info);
86 static void __reada_start_machine(struct btrfs_fs_info *fs_info);
87
88 static int reada_add_block(struct reada_control *rc, u64 logical,
89 struct btrfs_key *top, u64 generation);
90
91 /* recurses */
92 /* in case of err, eb might be NULL */
93 static void __readahead_hook(struct btrfs_fs_info *fs_info,
94 struct reada_extent *re, struct extent_buffer *eb,
95 int err)
96 {
97 int nritems;
98 int i;
99 u64 bytenr;
100 u64 generation;
101 struct list_head list;
102
103 spin_lock(&re->lock);
104 /*
105 * just take the full list from the extent. afterwards we
106 * don't need the lock anymore
107 */
108 list_replace_init(&re->extctl, &list);
109 re->scheduled = 0;
110 spin_unlock(&re->lock);
111
112 /*
113 * this is the error case, the extent buffer has not been
114 * read correctly. We won't access anything from it and
115 * just cleanup our data structures. Effectively this will
116 * cut the branch below this node from read ahead.
117 */
118 if (err)
119 goto cleanup;
120
121 /*
122 * FIXME: currently we just set nritems to 0 if this is a leaf,
123 * effectively ignoring the content. In a next step we could
124 * trigger more readahead depending from the content, e.g.
125 * fetch the checksums for the extents in the leaf.
126 */
127 if (!btrfs_header_level(eb))
128 goto cleanup;
129
130 nritems = btrfs_header_nritems(eb);
131 generation = btrfs_header_generation(eb);
132 for (i = 0; i < nritems; i++) {
133 struct reada_extctl *rec;
134 u64 n_gen;
135 struct btrfs_key key;
136 struct btrfs_key next_key;
137
138 btrfs_node_key_to_cpu(eb, &key, i);
139 if (i + 1 < nritems)
140 btrfs_node_key_to_cpu(eb, &next_key, i + 1);
141 else
142 next_key = re->top;
143 bytenr = btrfs_node_blockptr(eb, i);
144 n_gen = btrfs_node_ptr_generation(eb, i);
145
146 list_for_each_entry(rec, &list, list) {
147 struct reada_control *rc = rec->rc;
148
149 /*
150 * if the generation doesn't match, just ignore this
151 * extctl. This will probably cut off a branch from
152 * prefetch. Alternatively one could start a new (sub-)
153 * prefetch for this branch, starting again from root.
154 * FIXME: move the generation check out of this loop
155 */
156 #ifdef DEBUG
157 if (rec->generation != generation) {
158 btrfs_debug(fs_info,
159 "generation mismatch for (%llu,%d,%llu) %llu != %llu",
160 key.objectid, key.type, key.offset,
161 rec->generation, generation);
162 }
163 #endif
164 if (rec->generation == generation &&
165 btrfs_comp_cpu_keys(&key, &rc->key_end) < 0 &&
166 btrfs_comp_cpu_keys(&next_key, &rc->key_start) > 0)
167 reada_add_block(rc, bytenr, &next_key, n_gen);
168 }
169 }
170
171 cleanup:
172 /*
173 * free extctl records
174 */
175 while (!list_empty(&list)) {
176 struct reada_control *rc;
177 struct reada_extctl *rec;
178
179 rec = list_first_entry(&list, struct reada_extctl, list);
180 list_del(&rec->list);
181 rc = rec->rc;
182 kfree(rec);
183
184 kref_get(&rc->refcnt);
185 if (atomic_dec_and_test(&rc->elems)) {
186 kref_put(&rc->refcnt, reada_control_release);
187 wake_up(&rc->wait);
188 }
189 kref_put(&rc->refcnt, reada_control_release);
190
191 reada_extent_put(fs_info, re); /* one ref for each entry */
192 }
193
194 return;
195 }
196
197 int btree_readahead_hook(struct extent_buffer *eb, int err)
198 {
199 struct btrfs_fs_info *fs_info = eb->fs_info;
200 int ret = 0;
201 struct reada_extent *re;
202
203 /* find extent */
204 spin_lock(&fs_info->reada_lock);
205 re = radix_tree_lookup(&fs_info->reada_tree,
206 eb->start >> PAGE_SHIFT);
207 if (re)
208 re->refcnt++;
209 spin_unlock(&fs_info->reada_lock);
210 if (!re) {
211 ret = -1;
212 goto start_machine;
213 }
214
215 __readahead_hook(fs_info, re, eb, err);
216 reada_extent_put(fs_info, re); /* our ref */
217
218 start_machine:
219 reada_start_machine(fs_info);
220 return ret;
221 }
222
223 static struct reada_zone *reada_find_zone(struct btrfs_device *dev, u64 logical,
224 struct btrfs_bio *bbio)
225 {
226 struct btrfs_fs_info *fs_info = dev->fs_info;
227 int ret;
228 struct reada_zone *zone;
229 struct btrfs_block_group_cache *cache = NULL;
230 u64 start;
231 u64 end;
232 int i;
233
234 zone = NULL;
235 spin_lock(&fs_info->reada_lock);
236 ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
237 logical >> PAGE_SHIFT, 1);
238 if (ret == 1 && logical >= zone->start && logical <= zone->end) {
239 kref_get(&zone->refcnt);
240 spin_unlock(&fs_info->reada_lock);
241 return zone;
242 }
243
244 spin_unlock(&fs_info->reada_lock);
245
246 cache = btrfs_lookup_block_group(fs_info, logical);
247 if (!cache)
248 return NULL;
249
250 start = cache->key.objectid;
251 end = start + cache->key.offset - 1;
252 btrfs_put_block_group(cache);
253
254 zone = kzalloc(sizeof(*zone), GFP_KERNEL);
255 if (!zone)
256 return NULL;
257
258 ret = radix_tree_preload(GFP_KERNEL);
259 if (ret) {
260 kfree(zone);
261 return NULL;
262 }
263
264 zone->start = start;
265 zone->end = end;
266 INIT_LIST_HEAD(&zone->list);
267 spin_lock_init(&zone->lock);
268 zone->locked = 0;
269 kref_init(&zone->refcnt);
270 zone->elems = 0;
271 zone->device = dev; /* our device always sits at index 0 */
272 for (i = 0; i < bbio->num_stripes; ++i) {
273 /* bounds have already been checked */
274 zone->devs[i] = bbio->stripes[i].dev;
275 }
276 zone->ndevs = bbio->num_stripes;
277
278 spin_lock(&fs_info->reada_lock);
279 ret = radix_tree_insert(&dev->reada_zones,
280 (unsigned long)(zone->end >> PAGE_SHIFT),
281 zone);
282
283 if (ret == -EEXIST) {
284 kfree(zone);
285 ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
286 logical >> PAGE_SHIFT, 1);
287 if (ret == 1 && logical >= zone->start && logical <= zone->end)
288 kref_get(&zone->refcnt);
289 else
290 zone = NULL;
291 }
292 spin_unlock(&fs_info->reada_lock);
293 radix_tree_preload_end();
294
295 return zone;
296 }
297
298 static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info,
299 u64 logical,
300 struct btrfs_key *top)
301 {
302 int ret;
303 struct reada_extent *re = NULL;
304 struct reada_extent *re_exist = NULL;
305 struct btrfs_bio *bbio = NULL;
306 struct btrfs_device *dev;
307 struct btrfs_device *prev_dev;
308 u64 length;
309 int real_stripes;
310 int nzones = 0;
311 unsigned long index = logical >> PAGE_SHIFT;
312 int dev_replace_is_ongoing;
313 int have_zone = 0;
314
315 spin_lock(&fs_info->reada_lock);
316 re = radix_tree_lookup(&fs_info->reada_tree, index);
317 if (re)
318 re->refcnt++;
319 spin_unlock(&fs_info->reada_lock);
320
321 if (re)
322 return re;
323
324 re = kzalloc(sizeof(*re), GFP_KERNEL);
325 if (!re)
326 return NULL;
327
328 re->logical = logical;
329 re->top = *top;
330 INIT_LIST_HEAD(&re->extctl);
331 spin_lock_init(&re->lock);
332 re->refcnt = 1;
333
334 /*
335 * map block
336 */
337 length = fs_info->nodesize;
338 ret = btrfs_map_block(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,
339 &length, &bbio, 0);
340 if (ret || !bbio || length < fs_info->nodesize)
341 goto error;
342
343 if (bbio->num_stripes > BTRFS_MAX_MIRRORS) {
344 btrfs_err(fs_info,
345 "readahead: more than %d copies not supported",
346 BTRFS_MAX_MIRRORS);
347 goto error;
348 }
349
350 real_stripes = bbio->num_stripes - bbio->num_tgtdevs;
351 for (nzones = 0; nzones < real_stripes; ++nzones) {
352 struct reada_zone *zone;
353
354 dev = bbio->stripes[nzones].dev;
355
356 /* cannot read ahead on missing device. */
357 if (!dev->bdev)
358 continue;
359
360 zone = reada_find_zone(dev, logical, bbio);
361 if (!zone)
362 continue;
363
364 re->zones[re->nzones++] = zone;
365 spin_lock(&zone->lock);
366 if (!zone->elems)
367 kref_get(&zone->refcnt);
368 ++zone->elems;
369 spin_unlock(&zone->lock);
370 spin_lock(&fs_info->reada_lock);
371 kref_put(&zone->refcnt, reada_zone_release);
372 spin_unlock(&fs_info->reada_lock);
373 }
374 if (re->nzones == 0) {
375 /* not a single zone found, error and out */
376 goto error;
377 }
378
379 ret = radix_tree_preload(GFP_KERNEL);
380 if (ret)
381 goto error;
382
383 /* insert extent in reada_tree + all per-device trees, all or nothing */
384 btrfs_dev_replace_read_lock(&fs_info->dev_replace);
385 spin_lock(&fs_info->reada_lock);
386 ret = radix_tree_insert(&fs_info->reada_tree, index, re);
387 if (ret == -EEXIST) {
388 re_exist = radix_tree_lookup(&fs_info->reada_tree, index);
389 re_exist->refcnt++;
390 spin_unlock(&fs_info->reada_lock);
391 btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
392 radix_tree_preload_end();
393 goto error;
394 }
395 if (ret) {
396 spin_unlock(&fs_info->reada_lock);
397 btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
398 radix_tree_preload_end();
399 goto error;
400 }
401 radix_tree_preload_end();
402 prev_dev = NULL;
403 dev_replace_is_ongoing = btrfs_dev_replace_is_ongoing(
404 &fs_info->dev_replace);
405 for (nzones = 0; nzones < re->nzones; ++nzones) {
406 dev = re->zones[nzones]->device;
407
408 if (dev == prev_dev) {
409 /*
410 * in case of DUP, just add the first zone. As both
411 * are on the same device, there's nothing to gain
412 * from adding both.
413 * Also, it wouldn't work, as the tree is per device
414 * and adding would fail with EEXIST
415 */
416 continue;
417 }
418 if (!dev->bdev)
419 continue;
420
421 if (dev_replace_is_ongoing &&
422 dev == fs_info->dev_replace.tgtdev) {
423 /*
424 * as this device is selected for reading only as
425 * a last resort, skip it for read ahead.
426 */
427 continue;
428 }
429 prev_dev = dev;
430 ret = radix_tree_insert(&dev->reada_extents, index, re);
431 if (ret) {
432 while (--nzones >= 0) {
433 dev = re->zones[nzones]->device;
434 BUG_ON(dev == NULL);
435 /* ignore whether the entry was inserted */
436 radix_tree_delete(&dev->reada_extents, index);
437 }
438 radix_tree_delete(&fs_info->reada_tree, index);
439 spin_unlock(&fs_info->reada_lock);
440 btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
441 goto error;
442 }
443 have_zone = 1;
444 }
445 spin_unlock(&fs_info->reada_lock);
446 btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
447
448 if (!have_zone)
449 goto error;
450
451 btrfs_put_bbio(bbio);
452 return re;
453
454 error:
455 for (nzones = 0; nzones < re->nzones; ++nzones) {
456 struct reada_zone *zone;
457
458 zone = re->zones[nzones];
459 kref_get(&zone->refcnt);
460 spin_lock(&zone->lock);
461 --zone->elems;
462 if (zone->elems == 0) {
463 /*
464 * no fs_info->reada_lock needed, as this can't be
465 * the last ref
466 */
467 kref_put(&zone->refcnt, reada_zone_release);
468 }
469 spin_unlock(&zone->lock);
470
471 spin_lock(&fs_info->reada_lock);
472 kref_put(&zone->refcnt, reada_zone_release);
473 spin_unlock(&fs_info->reada_lock);
474 }
475 btrfs_put_bbio(bbio);
476 kfree(re);
477 return re_exist;
478 }
479
480 static void reada_extent_put(struct btrfs_fs_info *fs_info,
481 struct reada_extent *re)
482 {
483 int i;
484 unsigned long index = re->logical >> PAGE_SHIFT;
485
486 spin_lock(&fs_info->reada_lock);
487 if (--re->refcnt) {
488 spin_unlock(&fs_info->reada_lock);
489 return;
490 }
491
492 radix_tree_delete(&fs_info->reada_tree, index);
493 for (i = 0; i < re->nzones; ++i) {
494 struct reada_zone *zone = re->zones[i];
495
496 radix_tree_delete(&zone->device->reada_extents, index);
497 }
498
499 spin_unlock(&fs_info->reada_lock);
500
501 for (i = 0; i < re->nzones; ++i) {
502 struct reada_zone *zone = re->zones[i];
503
504 kref_get(&zone->refcnt);
505 spin_lock(&zone->lock);
506 --zone->elems;
507 if (zone->elems == 0) {
508 /* no fs_info->reada_lock needed, as this can't be
509 * the last ref */
510 kref_put(&zone->refcnt, reada_zone_release);
511 }
512 spin_unlock(&zone->lock);
513
514 spin_lock(&fs_info->reada_lock);
515 kref_put(&zone->refcnt, reada_zone_release);
516 spin_unlock(&fs_info->reada_lock);
517 }
518
519 kfree(re);
520 }
521
522 static void reada_zone_release(struct kref *kref)
523 {
524 struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt);
525
526 radix_tree_delete(&zone->device->reada_zones,
527 zone->end >> PAGE_SHIFT);
528
529 kfree(zone);
530 }
531
532 static void reada_control_release(struct kref *kref)
533 {
534 struct reada_control *rc = container_of(kref, struct reada_control,
535 refcnt);
536
537 kfree(rc);
538 }
539
540 static int reada_add_block(struct reada_control *rc, u64 logical,
541 struct btrfs_key *top, u64 generation)
542 {
543 struct btrfs_fs_info *fs_info = rc->fs_info;
544 struct reada_extent *re;
545 struct reada_extctl *rec;
546
547 /* takes one ref */
548 re = reada_find_extent(fs_info, logical, top);
549 if (!re)
550 return -1;
551
552 rec = kzalloc(sizeof(*rec), GFP_KERNEL);
553 if (!rec) {
554 reada_extent_put(fs_info, re);
555 return -ENOMEM;
556 }
557
558 rec->rc = rc;
559 rec->generation = generation;
560 atomic_inc(&rc->elems);
561
562 spin_lock(&re->lock);
563 list_add_tail(&rec->list, &re->extctl);
564 spin_unlock(&re->lock);
565
566 /* leave the ref on the extent */
567
568 return 0;
569 }
570
571 /*
572 * called with fs_info->reada_lock held
573 */
574 static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock)
575 {
576 int i;
577 unsigned long index = zone->end >> PAGE_SHIFT;
578
579 for (i = 0; i < zone->ndevs; ++i) {
580 struct reada_zone *peer;
581 peer = radix_tree_lookup(&zone->devs[i]->reada_zones, index);
582 if (peer && peer->device != zone->device)
583 peer->locked = lock;
584 }
585 }
586
587 /*
588 * called with fs_info->reada_lock held
589 */
590 static int reada_pick_zone(struct btrfs_device *dev)
591 {
592 struct reada_zone *top_zone = NULL;
593 struct reada_zone *top_locked_zone = NULL;
594 u64 top_elems = 0;
595 u64 top_locked_elems = 0;
596 unsigned long index = 0;
597 int ret;
598
599 if (dev->reada_curr_zone) {
600 reada_peer_zones_set_lock(dev->reada_curr_zone, 0);
601 kref_put(&dev->reada_curr_zone->refcnt, reada_zone_release);
602 dev->reada_curr_zone = NULL;
603 }
604 /* pick the zone with the most elements */
605 while (1) {
606 struct reada_zone *zone;
607
608 ret = radix_tree_gang_lookup(&dev->reada_zones,
609 (void **)&zone, index, 1);
610 if (ret == 0)
611 break;
612 index = (zone->end >> PAGE_SHIFT) + 1;
613 if (zone->locked) {
614 if (zone->elems > top_locked_elems) {
615 top_locked_elems = zone->elems;
616 top_locked_zone = zone;
617 }
618 } else {
619 if (zone->elems > top_elems) {
620 top_elems = zone->elems;
621 top_zone = zone;
622 }
623 }
624 }
625 if (top_zone)
626 dev->reada_curr_zone = top_zone;
627 else if (top_locked_zone)
628 dev->reada_curr_zone = top_locked_zone;
629 else
630 return 0;
631
632 dev->reada_next = dev->reada_curr_zone->start;
633 kref_get(&dev->reada_curr_zone->refcnt);
634 reada_peer_zones_set_lock(dev->reada_curr_zone, 1);
635
636 return 1;
637 }
638
639 static int reada_start_machine_dev(struct btrfs_device *dev)
640 {
641 struct btrfs_fs_info *fs_info = dev->fs_info;
642 struct reada_extent *re = NULL;
643 int mirror_num = 0;
644 struct extent_buffer *eb = NULL;
645 u64 logical;
646 int ret;
647 int i;
648
649 spin_lock(&fs_info->reada_lock);
650 if (dev->reada_curr_zone == NULL) {
651 ret = reada_pick_zone(dev);
652 if (!ret) {
653 spin_unlock(&fs_info->reada_lock);
654 return 0;
655 }
656 }
657 /*
658 * FIXME currently we issue the reads one extent at a time. If we have
659 * a contiguous block of extents, we could also coagulate them or use
660 * plugging to speed things up
661 */
662 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
663 dev->reada_next >> PAGE_SHIFT, 1);
664 if (ret == 0 || re->logical > dev->reada_curr_zone->end) {
665 ret = reada_pick_zone(dev);
666 if (!ret) {
667 spin_unlock(&fs_info->reada_lock);
668 return 0;
669 }
670 re = NULL;
671 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
672 dev->reada_next >> PAGE_SHIFT, 1);
673 }
674 if (ret == 0) {
675 spin_unlock(&fs_info->reada_lock);
676 return 0;
677 }
678 dev->reada_next = re->logical + fs_info->nodesize;
679 re->refcnt++;
680
681 spin_unlock(&fs_info->reada_lock);
682
683 spin_lock(&re->lock);
684 if (re->scheduled || list_empty(&re->extctl)) {
685 spin_unlock(&re->lock);
686 reada_extent_put(fs_info, re);
687 return 0;
688 }
689 re->scheduled = 1;
690 spin_unlock(&re->lock);
691
692 /*
693 * find mirror num
694 */
695 for (i = 0; i < re->nzones; ++i) {
696 if (re->zones[i]->device == dev) {
697 mirror_num = i + 1;
698 break;
699 }
700 }
701 logical = re->logical;
702
703 atomic_inc(&dev->reada_in_flight);
704 ret = reada_tree_block_flagged(fs_info, logical, mirror_num, &eb);
705 if (ret)
706 __readahead_hook(fs_info, re, NULL, ret);
707 else if (eb)
708 __readahead_hook(fs_info, re, eb, ret);
709
710 if (eb)
711 free_extent_buffer(eb);
712
713 atomic_dec(&dev->reada_in_flight);
714 reada_extent_put(fs_info, re);
715
716 return 1;
717
718 }
719
720 static void reada_start_machine_worker(struct btrfs_work *work)
721 {
722 struct reada_machine_work *rmw;
723 int old_ioprio;
724
725 rmw = container_of(work, struct reada_machine_work, work);
726
727 old_ioprio = IOPRIO_PRIO_VALUE(task_nice_ioclass(current),
728 task_nice_ioprio(current));
729 set_task_ioprio(current, BTRFS_IOPRIO_READA);
730 __reada_start_machine(rmw->fs_info);
731 set_task_ioprio(current, old_ioprio);
732
733 atomic_dec(&rmw->fs_info->reada_works_cnt);
734
735 kfree(rmw);
736 }
737
738 static void __reada_start_machine(struct btrfs_fs_info *fs_info)
739 {
740 struct btrfs_device *device;
741 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
742 u64 enqueued;
743 u64 total = 0;
744 int i;
745
746 again:
747 do {
748 enqueued = 0;
749 mutex_lock(&fs_devices->device_list_mutex);
750 list_for_each_entry(device, &fs_devices->devices, dev_list) {
751 if (atomic_read(&device->reada_in_flight) <
752 MAX_IN_FLIGHT)
753 enqueued += reada_start_machine_dev(device);
754 }
755 mutex_unlock(&fs_devices->device_list_mutex);
756 total += enqueued;
757 } while (enqueued && total < 10000);
758 if (fs_devices->seed) {
759 fs_devices = fs_devices->seed;
760 goto again;
761 }
762
763 if (enqueued == 0)
764 return;
765
766 /*
767 * If everything is already in the cache, this is effectively single
768 * threaded. To a) not hold the caller for too long and b) to utilize
769 * more cores, we broke the loop above after 10000 iterations and now
770 * enqueue to workers to finish it. This will distribute the load to
771 * the cores.
772 */
773 for (i = 0; i < 2; ++i) {
774 reada_start_machine(fs_info);
775 if (atomic_read(&fs_info->reada_works_cnt) >
776 BTRFS_MAX_MIRRORS * 2)
777 break;
778 }
779 }
780
781 static void reada_start_machine(struct btrfs_fs_info *fs_info)
782 {
783 struct reada_machine_work *rmw;
784
785 rmw = kzalloc(sizeof(*rmw), GFP_KERNEL);
786 if (!rmw) {
787 /* FIXME we cannot handle this properly right now */
788 BUG();
789 }
790 btrfs_init_work(&rmw->work, btrfs_readahead_helper,
791 reada_start_machine_worker, NULL, NULL);
792 rmw->fs_info = fs_info;
793
794 btrfs_queue_work(fs_info->readahead_workers, &rmw->work);
795 atomic_inc(&fs_info->reada_works_cnt);
796 }
797
798 #ifdef DEBUG
799 static void dump_devs(struct btrfs_fs_info *fs_info, int all)
800 {
801 struct btrfs_device *device;
802 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
803 unsigned long index;
804 int ret;
805 int i;
806 int j;
807 int cnt;
808
809 spin_lock(&fs_info->reada_lock);
810 list_for_each_entry(device, &fs_devices->devices, dev_list) {
811 btrfs_debug(fs_info, "dev %lld has %d in flight", device->devid,
812 atomic_read(&device->reada_in_flight));
813 index = 0;
814 while (1) {
815 struct reada_zone *zone;
816 ret = radix_tree_gang_lookup(&device->reada_zones,
817 (void **)&zone, index, 1);
818 if (ret == 0)
819 break;
820 pr_debug(" zone %llu-%llu elems %llu locked %d devs",
821 zone->start, zone->end, zone->elems,
822 zone->locked);
823 for (j = 0; j < zone->ndevs; ++j) {
824 pr_cont(" %lld",
825 zone->devs[j]->devid);
826 }
827 if (device->reada_curr_zone == zone)
828 pr_cont(" curr off %llu",
829 device->reada_next - zone->start);
830 pr_cont("\n");
831 index = (zone->end >> PAGE_SHIFT) + 1;
832 }
833 cnt = 0;
834 index = 0;
835 while (all) {
836 struct reada_extent *re = NULL;
837
838 ret = radix_tree_gang_lookup(&device->reada_extents,
839 (void **)&re, index, 1);
840 if (ret == 0)
841 break;
842 pr_debug(" re: logical %llu size %u empty %d scheduled %d",
843 re->logical, fs_info->nodesize,
844 list_empty(&re->extctl), re->scheduled);
845
846 for (i = 0; i < re->nzones; ++i) {
847 pr_cont(" zone %llu-%llu devs",
848 re->zones[i]->start,
849 re->zones[i]->end);
850 for (j = 0; j < re->zones[i]->ndevs; ++j) {
851 pr_cont(" %lld",
852 re->zones[i]->devs[j]->devid);
853 }
854 }
855 pr_cont("\n");
856 index = (re->logical >> PAGE_SHIFT) + 1;
857 if (++cnt > 15)
858 break;
859 }
860 }
861
862 index = 0;
863 cnt = 0;
864 while (all) {
865 struct reada_extent *re = NULL;
866
867 ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re,
868 index, 1);
869 if (ret == 0)
870 break;
871 if (!re->scheduled) {
872 index = (re->logical >> PAGE_SHIFT) + 1;
873 continue;
874 }
875 pr_debug("re: logical %llu size %u list empty %d scheduled %d",
876 re->logical, fs_info->nodesize,
877 list_empty(&re->extctl), re->scheduled);
878 for (i = 0; i < re->nzones; ++i) {
879 pr_cont(" zone %llu-%llu devs",
880 re->zones[i]->start,
881 re->zones[i]->end);
882 for (j = 0; j < re->zones[i]->ndevs; ++j) {
883 pr_cont(" %lld",
884 re->zones[i]->devs[j]->devid);
885 }
886 }
887 pr_cont("\n");
888 index = (re->logical >> PAGE_SHIFT) + 1;
889 }
890 spin_unlock(&fs_info->reada_lock);
891 }
892 #endif
893
894 /*
895 * interface
896 */
897 struct reada_control *btrfs_reada_add(struct btrfs_root *root,
898 struct btrfs_key *key_start, struct btrfs_key *key_end)
899 {
900 struct reada_control *rc;
901 u64 start;
902 u64 generation;
903 int ret;
904 struct extent_buffer *node;
905 static struct btrfs_key max_key = {
906 .objectid = (u64)-1,
907 .type = (u8)-1,
908 .offset = (u64)-1
909 };
910
911 rc = kzalloc(sizeof(*rc), GFP_KERNEL);
912 if (!rc)
913 return ERR_PTR(-ENOMEM);
914
915 rc->fs_info = root->fs_info;
916 rc->key_start = *key_start;
917 rc->key_end = *key_end;
918 atomic_set(&rc->elems, 0);
919 init_waitqueue_head(&rc->wait);
920 kref_init(&rc->refcnt);
921 kref_get(&rc->refcnt); /* one ref for having elements */
922
923 node = btrfs_root_node(root);
924 start = node->start;
925 generation = btrfs_header_generation(node);
926 free_extent_buffer(node);
927
928 ret = reada_add_block(rc, start, &max_key, generation);
929 if (ret) {
930 kfree(rc);
931 return ERR_PTR(ret);
932 }
933
934 reada_start_machine(root->fs_info);
935
936 return rc;
937 }
938
939 #ifdef DEBUG
940 int btrfs_reada_wait(void *handle)
941 {
942 struct reada_control *rc = handle;
943 struct btrfs_fs_info *fs_info = rc->fs_info;
944
945 while (atomic_read(&rc->elems)) {
946 if (!atomic_read(&fs_info->reada_works_cnt))
947 reada_start_machine(fs_info);
948 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
949 5 * HZ);
950 dump_devs(fs_info, atomic_read(&rc->elems) < 10 ? 1 : 0);
951 }
952
953 dump_devs(fs_info, atomic_read(&rc->elems) < 10 ? 1 : 0);
954
955 kref_put(&rc->refcnt, reada_control_release);
956
957 return 0;
958 }
959 #else
960 int btrfs_reada_wait(void *handle)
961 {
962 struct reada_control *rc = handle;
963 struct btrfs_fs_info *fs_info = rc->fs_info;
964
965 while (atomic_read(&rc->elems)) {
966 if (!atomic_read(&fs_info->reada_works_cnt))
967 reada_start_machine(fs_info);
968 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
969 (HZ + 9) / 10);
970 }
971
972 kref_put(&rc->refcnt, reada_control_release);
973
974 return 0;
975 }
976 #endif
977
978 void btrfs_reada_detach(void *handle)
979 {
980 struct reada_control *rc = handle;
981
982 kref_put(&rc->refcnt, reada_control_release);
983 }
Linux with added FPC-III support