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-rw-r--r--fs/btrfs/reada.c951
1 files changed, 951 insertions, 0 deletions
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
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+++ b/fs/btrfs/reada.c
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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
31#undef DEBUG
32
33/*
34 * This is the implementation for the generic read ahead framework.
35 *
36 * To trigger a readahead, btrfs_reada_add must be called. It will start
37 * a read ahead for the given range [start, end) on tree root. The returned
38 * handle can either be used to wait on the readahead to finish
39 * (btrfs_reada_wait), or to send it to the background (btrfs_reada_detach).
40 *
41 * The read ahead works as follows:
42 * On btrfs_reada_add, the root of the tree is inserted into a radix_tree.
43 * reada_start_machine will then search for extents to prefetch and trigger
44 * some reads. When a read finishes for a node, all contained node/leaf
45 * pointers that lie in the given range will also be enqueued. The reads will
46 * be triggered in sequential order, thus giving a big win over a naive
47 * enumeration. It will also make use of multi-device layouts. Each disk
48 * will have its on read pointer and all disks will by utilized in parallel.
49 * Also will no two disks read both sides of a mirror simultaneously, as this
50 * would waste seeking capacity. Instead both disks will read different parts
51 * of the filesystem.
52 * Any number of readaheads can be started in parallel. The read order will be
53 * determined globally, i.e. 2 parallel readaheads will normally finish faster
54 * than the 2 started one after another.
55 */
56
57#define MAX_MIRRORS 2
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 struct kref refcnt;
73 spinlock_t lock;
74 struct reada_zone *zones[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[MAX_MIRRORS]; /* full list, incl 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 kref_get(&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 printk(KERN_DEBUG "generation mismatch for "
192 "(%llu,%d,%llu) %llu != %llu\n",
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 int looped = 0;
254 struct reada_zone *zone;
255 struct btrfs_block_group_cache *cache = NULL;
256 u64 start;
257 u64 end;
258 int i;
259
260again:
261 zone = NULL;
262 spin_lock(&fs_info->reada_lock);
263 ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
264 logical >> PAGE_CACHE_SHIFT, 1);
265 if (ret == 1)
266 kref_get(&zone->refcnt);
267 spin_unlock(&fs_info->reada_lock);
268
269 if (ret == 1) {
270 if (logical >= zone->start && logical < zone->end)
271 return zone;
272 spin_lock(&fs_info->reada_lock);
273 kref_put(&zone->refcnt, reada_zone_release);
274 spin_unlock(&fs_info->reada_lock);
275 }
276
277 if (looped)
278 return NULL;
279
280 cache = btrfs_lookup_block_group(fs_info, logical);
281 if (!cache)
282 return NULL;
283
284 start = cache->key.objectid;
285 end = start + cache->key.offset - 1;
286 btrfs_put_block_group(cache);
287
288 zone = kzalloc(sizeof(*zone), GFP_NOFS);
289 if (!zone)
290 return NULL;
291
292 zone->start = start;
293 zone->end = end;
294 INIT_LIST_HEAD(&zone->list);
295 spin_lock_init(&zone->lock);
296 zone->locked = 0;
297 kref_init(&zone->refcnt);
298 zone->elems = 0;
299 zone->device = dev; /* our device always sits at index 0 */
300 for (i = 0; i < bbio->num_stripes; ++i) {
301 /* bounds have already been checked */
302 zone->devs[i] = bbio->stripes[i].dev;
303 }
304 zone->ndevs = bbio->num_stripes;
305
306 spin_lock(&fs_info->reada_lock);
307 ret = radix_tree_insert(&dev->reada_zones,
308 (unsigned long)zone->end >> PAGE_CACHE_SHIFT,
309 zone);
310 spin_unlock(&fs_info->reada_lock);
311
312 if (ret) {
313 kfree(zone);
314 looped = 1;
315 goto again;
316 }
317
318 return zone;
319}
320
321static struct reada_extent *reada_find_extent(struct btrfs_root *root,
322 u64 logical,
323 struct btrfs_key *top, int level)
324{
325 int ret;
326 int looped = 0;
327 struct reada_extent *re = NULL;
328 struct btrfs_fs_info *fs_info = root->fs_info;
329 struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
330 struct btrfs_bio *bbio = NULL;
331 struct btrfs_device *dev;
332 u32 blocksize;
333 u64 length;
334 int nzones = 0;
335 int i;
336 unsigned long index = logical >> PAGE_CACHE_SHIFT;
337
338again:
339 spin_lock(&fs_info->reada_lock);
340 re = radix_tree_lookup(&fs_info->reada_tree, index);
341 if (re)
342 kref_get(&re->refcnt);
343 spin_unlock(&fs_info->reada_lock);
344
345 if (re || looped)
346 return re;
347
348 re = kzalloc(sizeof(*re), GFP_NOFS);
349 if (!re)
350 return NULL;
351
352 blocksize = btrfs_level_size(root, level);
353 re->logical = logical;
354 re->blocksize = blocksize;
355 re->top = *top;
356 INIT_LIST_HEAD(&re->extctl);
357 spin_lock_init(&re->lock);
358 kref_init(&re->refcnt);
359
360 /*
361 * map block
362 */
363 length = blocksize;
364 ret = btrfs_map_block(map_tree, REQ_WRITE, logical, &length, &bbio, 0);
365 if (ret || !bbio || length < blocksize)
366 goto error;
367
368 if (bbio->num_stripes > MAX_MIRRORS) {
369 printk(KERN_ERR "btrfs readahead: more than %d copies not "
370 "supported", 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 spin_lock(&fs_info->reada_lock);
400 ret = radix_tree_insert(&fs_info->reada_tree, index, re);
401 if (ret) {
402 spin_unlock(&fs_info->reada_lock);
403 if (ret != -ENOMEM) {
404 /* someone inserted the extent in the meantime */
405 looped = 1;
406 }
407 goto error;
408 }
409 for (i = 0; i < nzones; ++i) {
410 dev = bbio->stripes[i].dev;
411 ret = radix_tree_insert(&dev->reada_extents, index, re);
412 if (ret) {
413 while (--i >= 0) {
414 dev = bbio->stripes[i].dev;
415 BUG_ON(dev == NULL);
416 radix_tree_delete(&dev->reada_extents, index);
417 }
418 BUG_ON(fs_info == NULL);
419 radix_tree_delete(&fs_info->reada_tree, index);
420 spin_unlock(&fs_info->reada_lock);
421 goto error;
422 }
423 }
424 spin_unlock(&fs_info->reada_lock);
425
426 kfree(bbio);
427 return re;
428
429error:
430 while (nzones) {
431 struct reada_zone *zone;
432
433 --nzones;
434 zone = re->zones[nzones];
435 kref_get(&zone->refcnt);
436 spin_lock(&zone->lock);
437 --zone->elems;
438 if (zone->elems == 0) {
439 /*
440 * no fs_info->reada_lock needed, as this can't be
441 * the last ref
442 */
443 kref_put(&zone->refcnt, reada_zone_release);
444 }
445 spin_unlock(&zone->lock);
446
447 spin_lock(&fs_info->reada_lock);
448 kref_put(&zone->refcnt, reada_zone_release);
449 spin_unlock(&fs_info->reada_lock);
450 }
451 kfree(bbio);
452 kfree(re);
453 if (looped)
454 goto again;
455 return NULL;
456}
457
458static void reada_kref_dummy(struct kref *kr)
459{
460}
461
462static void reada_extent_put(struct btrfs_fs_info *fs_info,
463 struct reada_extent *re)
464{
465 int i;
466 unsigned long index = re->logical >> PAGE_CACHE_SHIFT;
467
468 spin_lock(&fs_info->reada_lock);
469 if (!kref_put(&re->refcnt, reada_kref_dummy)) {
470 spin_unlock(&fs_info->reada_lock);
471 return;
472 }
473
474 radix_tree_delete(&fs_info->reada_tree, index);
475 for (i = 0; i < re->nzones; ++i) {
476 struct reada_zone *zone = re->zones[i];
477
478 radix_tree_delete(&zone->device->reada_extents, index);
479 }
480
481 spin_unlock(&fs_info->reada_lock);
482
483 for (i = 0; i < re->nzones; ++i) {
484 struct reada_zone *zone = re->zones[i];
485
486 kref_get(&zone->refcnt);
487 spin_lock(&zone->lock);
488 --zone->elems;
489 if (zone->elems == 0) {
490 /* no fs_info->reada_lock needed, as this can't be
491 * the last ref */
492 kref_put(&zone->refcnt, reada_zone_release);
493 }
494 spin_unlock(&zone->lock);
495
496 spin_lock(&fs_info->reada_lock);
497 kref_put(&zone->refcnt, reada_zone_release);
498 spin_unlock(&fs_info->reada_lock);
499 }
500 if (re->scheduled_for)
501 atomic_dec(&re->scheduled_for->reada_in_flight);
502
503 kfree(re);
504}
505
506static void reada_zone_release(struct kref *kref)
507{
508 struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt);
509
510 radix_tree_delete(&zone->device->reada_zones,
511 zone->end >> PAGE_CACHE_SHIFT);
512
513 kfree(zone);
514}
515
516static void reada_control_release(struct kref *kref)
517{
518 struct reada_control *rc = container_of(kref, struct reada_control,
519 refcnt);
520
521 kfree(rc);
522}
523
524static int reada_add_block(struct reada_control *rc, u64 logical,
525 struct btrfs_key *top, int level, u64 generation)
526{
527 struct btrfs_root *root = rc->root;
528 struct reada_extent *re;
529 struct reada_extctl *rec;
530
531 re = reada_find_extent(root, logical, top, level); /* takes one ref */
532 if (!re)
533 return -1;
534
535 rec = kzalloc(sizeof(*rec), GFP_NOFS);
536 if (!rec) {
537 reada_extent_put(root->fs_info, re);
538 return -1;
539 }
540
541 rec->rc = rc;
542 rec->generation = generation;
543 atomic_inc(&rc->elems);
544
545 spin_lock(&re->lock);
546 list_add_tail(&rec->list, &re->extctl);
547 spin_unlock(&re->lock);
548
549 /* leave the ref on the extent */
550
551 return 0;
552}
553
554/*
555 * called with fs_info->reada_lock held
556 */
557static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock)
558{
559 int i;
560 unsigned long index = zone->end >> PAGE_CACHE_SHIFT;
561
562 for (i = 0; i < zone->ndevs; ++i) {
563 struct reada_zone *peer;
564 peer = radix_tree_lookup(&zone->devs[i]->reada_zones, index);
565 if (peer && peer->device != zone->device)
566 peer->locked = lock;
567 }
568}
569
570/*
571 * called with fs_info->reada_lock held
572 */
573static int reada_pick_zone(struct btrfs_device *dev)
574{
575 struct reada_zone *top_zone = NULL;
576 struct reada_zone *top_locked_zone = NULL;
577 u64 top_elems = 0;
578 u64 top_locked_elems = 0;
579 unsigned long index = 0;
580 int ret;
581
582 if (dev->reada_curr_zone) {
583 reada_peer_zones_set_lock(dev->reada_curr_zone, 0);
584 kref_put(&dev->reada_curr_zone->refcnt, reada_zone_release);
585 dev->reada_curr_zone = NULL;
586 }
587 /* pick the zone with the most elements */
588 while (1) {
589 struct reada_zone *zone;
590
591 ret = radix_tree_gang_lookup(&dev->reada_zones,
592 (void **)&zone, index, 1);
593 if (ret == 0)
594 break;
595 index = (zone->end >> PAGE_CACHE_SHIFT) + 1;
596 if (zone->locked) {
597 if (zone->elems > top_locked_elems) {
598 top_locked_elems = zone->elems;
599 top_locked_zone = zone;
600 }
601 } else {
602 if (zone->elems > top_elems) {
603 top_elems = zone->elems;
604 top_zone = zone;
605 }
606 }
607 }
608 if (top_zone)
609 dev->reada_curr_zone = top_zone;
610 else if (top_locked_zone)
611 dev->reada_curr_zone = top_locked_zone;
612 else
613 return 0;
614
615 dev->reada_next = dev->reada_curr_zone->start;
616 kref_get(&dev->reada_curr_zone->refcnt);
617 reada_peer_zones_set_lock(dev->reada_curr_zone, 1);
618
619 return 1;
620}
621
622static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
623 struct btrfs_device *dev)
624{
625 struct reada_extent *re = NULL;
626 int mirror_num = 0;
627 struct extent_buffer *eb = NULL;
628 u64 logical;
629 u32 blocksize;
630 int ret;
631 int i;
632 int need_kick = 0;
633
634 spin_lock(&fs_info->reada_lock);
635 if (dev->reada_curr_zone == NULL) {
636 ret = reada_pick_zone(dev);
637 if (!ret) {
638 spin_unlock(&fs_info->reada_lock);
639 return 0;
640 }
641 }
642 /*
643 * FIXME currently we issue the reads one extent at a time. If we have
644 * a contiguous block of extents, we could also coagulate them or use
645 * plugging to speed things up
646 */
647 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
648 dev->reada_next >> PAGE_CACHE_SHIFT, 1);
649 if (ret == 0 || re->logical >= dev->reada_curr_zone->end) {
650 ret = reada_pick_zone(dev);
651 if (!ret) {
652 spin_unlock(&fs_info->reada_lock);
653 return 0;
654 }
655 re = NULL;
656 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
657 dev->reada_next >> PAGE_CACHE_SHIFT, 1);
658 }
659 if (ret == 0) {
660 spin_unlock(&fs_info->reada_lock);
661 return 0;
662 }
663 dev->reada_next = re->logical + re->blocksize;
664 kref_get(&re->refcnt);
665
666 spin_unlock(&fs_info->reada_lock);
667
668 /*
669 * find mirror num
670 */
671 for (i = 0; i < re->nzones; ++i) {
672 if (re->zones[i]->device == dev) {
673 mirror_num = i + 1;
674 break;
675 }
676 }
677 logical = re->logical;
678 blocksize = re->blocksize;
679
680 spin_lock(&re->lock);
681 if (re->scheduled_for == NULL) {
682 re->scheduled_for = dev;
683 need_kick = 1;
684 }
685 spin_unlock(&re->lock);
686
687 reada_extent_put(fs_info, re);
688
689 if (!need_kick)
690 return 0;
691
692 atomic_inc(&dev->reada_in_flight);
693 ret = reada_tree_block_flagged(fs_info->extent_root, logical, blocksize,
694 mirror_num, &eb);
695 if (ret)
696 __readahead_hook(fs_info->extent_root, NULL, logical, ret);
697 else if (eb)
698 __readahead_hook(fs_info->extent_root, eb, eb->start, ret);
699
700 if (eb)
701 free_extent_buffer(eb);
702
703 return 1;
704
705}
706
707static void reada_start_machine_worker(struct btrfs_work *work)
708{
709 struct reada_machine_work *rmw;
710 struct btrfs_fs_info *fs_info;
711
712 rmw = container_of(work, struct reada_machine_work, work);
713 fs_info = rmw->fs_info;
714
715 kfree(rmw);
716
717 __reada_start_machine(fs_info);
718}
719
720static void __reada_start_machine(struct btrfs_fs_info *fs_info)
721{
722 struct btrfs_device *device;
723 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
724 u64 enqueued;
725 u64 total = 0;
726 int i;
727
728 do {
729 enqueued = 0;
730 list_for_each_entry(device, &fs_devices->devices, dev_list) {
731 if (atomic_read(&device->reada_in_flight) <
732 MAX_IN_FLIGHT)
733 enqueued += reada_start_machine_dev(fs_info,
734 device);
735 }
736 total += enqueued;
737 } while (enqueued && total < 10000);
738
739 if (enqueued == 0)
740 return;
741
742 /*
743 * If everything is already in the cache, this is effectively single
744 * threaded. To a) not hold the caller for too long and b) to utilize
745 * more cores, we broke the loop above after 10000 iterations and now
746 * enqueue to workers to finish it. This will distribute the load to
747 * the cores.
748 */
749 for (i = 0; i < 2; ++i)
750 reada_start_machine(fs_info);
751}
752
753static void reada_start_machine(struct btrfs_fs_info *fs_info)
754{
755 struct reada_machine_work *rmw;
756
757 rmw = kzalloc(sizeof(*rmw), GFP_NOFS);
758 if (!rmw) {
759 /* FIXME we cannot handle this properly right now */
760 BUG();
761 }
762 rmw->work.func = reada_start_machine_worker;
763 rmw->fs_info = fs_info;
764
765 btrfs_queue_worker(&fs_info->readahead_workers, &rmw->work);
766}
767
768#ifdef DEBUG
769static void dump_devs(struct btrfs_fs_info *fs_info, int all)
770{
771 struct btrfs_device *device;
772 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
773 unsigned long index;
774 int ret;
775 int i;
776 int j;
777 int cnt;
778
779 spin_lock(&fs_info->reada_lock);
780 list_for_each_entry(device, &fs_devices->devices, dev_list) {
781 printk(KERN_DEBUG "dev %lld has %d in flight\n", device->devid,
782 atomic_read(&device->reada_in_flight));
783 index = 0;
784 while (1) {
785 struct reada_zone *zone;
786 ret = radix_tree_gang_lookup(&device->reada_zones,
787 (void **)&zone, index, 1);
788 if (ret == 0)
789 break;
790 printk(KERN_DEBUG " zone %llu-%llu elems %llu locked "
791 "%d devs", zone->start, zone->end, zone->elems,
792 zone->locked);
793 for (j = 0; j < zone->ndevs; ++j) {
794 printk(KERN_CONT " %lld",
795 zone->devs[j]->devid);
796 }
797 if (device->reada_curr_zone == zone)
798 printk(KERN_CONT " curr off %llu",
799 device->reada_next - zone->start);
800 printk(KERN_CONT "\n");
801 index = (zone->end >> PAGE_CACHE_SHIFT) + 1;
802 }
803 cnt = 0;
804 index = 0;
805 while (all) {
806 struct reada_extent *re = NULL;
807
808 ret = radix_tree_gang_lookup(&device->reada_extents,
809 (void **)&re, index, 1);
810 if (ret == 0)
811 break;
812 printk(KERN_DEBUG
813 " re: logical %llu size %u empty %d for %lld",
814 re->logical, re->blocksize,
815 list_empty(&re->extctl), re->scheduled_for ?
816 re->scheduled_for->devid : -1);
817
818 for (i = 0; i < re->nzones; ++i) {
819 printk(KERN_CONT " zone %llu-%llu devs",
820 re->zones[i]->start,
821 re->zones[i]->end);
822 for (j = 0; j < re->zones[i]->ndevs; ++j) {
823 printk(KERN_CONT " %lld",
824 re->zones[i]->devs[j]->devid);
825 }
826 }
827 printk(KERN_CONT "\n");
828 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
829 if (++cnt > 15)
830 break;
831 }
832 }
833
834 index = 0;
835 cnt = 0;
836 while (all) {
837 struct reada_extent *re = NULL;
838
839 ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re,
840 index, 1);
841 if (ret == 0)
842 break;
843 if (!re->scheduled_for) {
844 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
845 continue;
846 }
847 printk(KERN_DEBUG
848 "re: logical %llu size %u list empty %d for %lld",
849 re->logical, re->blocksize, list_empty(&re->extctl),
850 re->scheduled_for ? re->scheduled_for->devid : -1);
851 for (i = 0; i < re->nzones; ++i) {
852 printk(KERN_CONT " zone %llu-%llu devs",
853 re->zones[i]->start,
854 re->zones[i]->end);
855 for (i = 0; i < re->nzones; ++i) {
856 printk(KERN_CONT " zone %llu-%llu devs",
857 re->zones[i]->start,
858 re->zones[i]->end);
859 for (j = 0; j < re->zones[i]->ndevs; ++j) {
860 printk(KERN_CONT " %lld",
861 re->zones[i]->devs[j]->devid);
862 }
863 }
864 }
865 printk(KERN_CONT "\n");
866 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
867 }
868 spin_unlock(&fs_info->reada_lock);
869}
870#endif
871
872/*
873 * interface
874 */
875struct reada_control *btrfs_reada_add(struct btrfs_root *root,
876 struct btrfs_key *key_start, struct btrfs_key *key_end)
877{
878 struct reada_control *rc;
879 u64 start;
880 u64 generation;
881 int level;
882 struct extent_buffer *node;
883 static struct btrfs_key max_key = {
884 .objectid = (u64)-1,
885 .type = (u8)-1,
886 .offset = (u64)-1
887 };
888
889 rc = kzalloc(sizeof(*rc), GFP_NOFS);
890 if (!rc)
891 return ERR_PTR(-ENOMEM);
892
893 rc->root = root;
894 rc->key_start = *key_start;
895 rc->key_end = *key_end;
896 atomic_set(&rc->elems, 0);
897 init_waitqueue_head(&rc->wait);
898 kref_init(&rc->refcnt);
899 kref_get(&rc->refcnt); /* one ref for having elements */
900
901 node = btrfs_root_node(root);
902 start = node->start;
903 level = btrfs_header_level(node);
904 generation = btrfs_header_generation(node);
905 free_extent_buffer(node);
906
907 reada_add_block(rc, start, &max_key, level, generation);
908
909 reada_start_machine(root->fs_info);
910
911 return rc;
912}
913
914#ifdef DEBUG
915int btrfs_reada_wait(void *handle)
916{
917 struct reada_control *rc = handle;
918
919 while (atomic_read(&rc->elems)) {
920 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
921 5 * HZ);
922 dump_devs(rc->root->fs_info, rc->elems < 10 ? 1 : 0);
923 }
924
925 dump_devs(rc->root->fs_info, rc->elems < 10 ? 1 : 0);
926
927 kref_put(&rc->refcnt, reada_control_release);
928
929 return 0;
930}
931#else
932int btrfs_reada_wait(void *handle)
933{
934 struct reada_control *rc = handle;
935
936 while (atomic_read(&rc->elems)) {
937 wait_event(rc->wait, atomic_read(&rc->elems) == 0);
938 }
939
940 kref_put(&rc->refcnt, reada_control_release);
941
942 return 0;
943}
944#endif
945
946void btrfs_reada_detach(void *handle)
947{
948 struct reada_control *rc = handle;
949
950 kref_put(&rc->refcnt, reada_control_release);
951}
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-14 06:40:04 -0500