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-rw-r--r--fs/btrfs/Makefile3
-rw-r--r--fs/btrfs/ctree.h16
-rw-r--r--fs/btrfs/reada.c949
3 files changed, 967 insertions, 1 deletions
diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index 40e6ac08c21f..bdd6fb238ce1 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -7,6 +7,7 @@ btrfs-y += super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
7 extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \ 7 extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \
8 extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \ 8 extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \
9 export.o tree-log.o free-space-cache.o zlib.o lzo.o \ 9 export.o tree-log.o free-space-cache.o zlib.o lzo.o \
10 compression.o delayed-ref.o relocation.o delayed-inode.o scrub.o 10 compression.o delayed-ref.o relocation.o delayed-inode.o scrub.o \
11 reada.o
11 12
12btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o 13btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index f71fd24cc152..370af767440d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2702,4 +2702,20 @@ int btrfs_scrub_cancel_devid(struct btrfs_root *root, u64 devid);
2702int btrfs_scrub_progress(struct btrfs_root *root, u64 devid, 2702int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
2703 struct btrfs_scrub_progress *progress); 2703 struct btrfs_scrub_progress *progress);
2704 2704
2705/* reada.c */
2706struct reada_control {
2707 struct btrfs_root *root; /* tree to prefetch */
2708 struct btrfs_key key_start;
2709 struct btrfs_key key_end; /* exclusive */
2710 atomic_t elems;
2711 struct kref refcnt;
2712 wait_queue_head_t wait;
2713};
2714struct reada_control *btrfs_reada_add(struct btrfs_root *root,
2715 struct btrfs_key *start, struct btrfs_key *end);
2716int btrfs_reada_wait(void *handle);
2717void btrfs_reada_detach(void *handle);
2718int btree_readahead_hook(struct btrfs_root *root, struct extent_buffer *eb,
2719 u64 start, int err);
2720
2705#endif 2721#endif
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
new file mode 100644
index 000000000000..2b701d082227
--- /dev/null
+++ b/fs/btrfs/reada.c
@@ -0,0 +1,949 @@
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_multi_bio *multi)
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 < multi->num_stripes; ++i) {
301 /* bounds have already been checked */
302 zone->devs[i] = multi->stripes[i].dev;
303 }
304 zone->ndevs = multi->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_multi_bio *multi = 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, &multi, 0);
365 if (ret || !multi || length < blocksize)
366 goto error;
367
368 if (multi->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 < multi->num_stripes; ++nzones) {
375 struct reada_zone *zone;
376
377 dev = multi->stripes[nzones].dev;
378 zone = reada_find_zone(fs_info, dev, logical, multi);
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 = multi->stripes[i].dev;
411 ret = radix_tree_insert(&dev->reada_extents, index, re);
412 if (ret) {
413 while (--i >= 0) {
414 dev = multi->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 return re;
427
428error:
429 while (nzones) {
430 struct reada_zone *zone;
431
432 --nzones;
433 zone = re->zones[nzones];
434 kref_get(&zone->refcnt);
435 spin_lock(&zone->lock);
436 --zone->elems;
437 if (zone->elems == 0) {
438 /*
439 * no fs_info->reada_lock needed, as this can't be
440 * the last ref
441 */
442 kref_put(&zone->refcnt, reada_zone_release);
443 }
444 spin_unlock(&zone->lock);
445
446 spin_lock(&fs_info->reada_lock);
447 kref_put(&zone->refcnt, reada_zone_release);
448 spin_unlock(&fs_info->reada_lock);
449 }
450 kfree(re);
451 if (looped)
452 goto again;
453 return NULL;
454}
455
456static void reada_kref_dummy(struct kref *kr)
457{
458}
459
460static void reada_extent_put(struct btrfs_fs_info *fs_info,
461 struct reada_extent *re)
462{
463 int i;
464 unsigned long index = re->logical >> PAGE_CACHE_SHIFT;
465
466 spin_lock(&fs_info->reada_lock);
467 if (!kref_put(&re->refcnt, reada_kref_dummy)) {
468 spin_unlock(&fs_info->reada_lock);
469 return;
470 }
471
472 radix_tree_delete(&fs_info->reada_tree, index);
473 for (i = 0; i < re->nzones; ++i) {
474 struct reada_zone *zone = re->zones[i];
475
476 radix_tree_delete(&zone->device->reada_extents, index);
477 }
478
479 spin_unlock(&fs_info->reada_lock);
480
481 for (i = 0; i < re->nzones; ++i) {
482 struct reada_zone *zone = re->zones[i];
483
484 kref_get(&zone->refcnt);
485 spin_lock(&zone->lock);
486 --zone->elems;
487 if (zone->elems == 0) {
488 /* no fs_info->reada_lock needed, as this can't be
489 * the last ref */
490 kref_put(&zone->refcnt, reada_zone_release);
491 }
492 spin_unlock(&zone->lock);
493
494 spin_lock(&fs_info->reada_lock);
495 kref_put(&zone->refcnt, reada_zone_release);
496 spin_unlock(&fs_info->reada_lock);
497 }
498 if (re->scheduled_for)
499 atomic_dec(&re->scheduled_for->reada_in_flight);
500
501 kfree(re);
502}
503
504static void reada_zone_release(struct kref *kref)
505{
506 struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt);
507
508 radix_tree_delete(&zone->device->reada_zones,
509 zone->end >> PAGE_CACHE_SHIFT);
510
511 kfree(zone);
512}
513
514static void reada_control_release(struct kref *kref)
515{
516 struct reada_control *rc = container_of(kref, struct reada_control,
517 refcnt);
518
519 kfree(rc);
520}
521
522static int reada_add_block(struct reada_control *rc, u64 logical,
523 struct btrfs_key *top, int level, u64 generation)
524{
525 struct btrfs_root *root = rc->root;
526 struct reada_extent *re;
527 struct reada_extctl *rec;
528
529 re = reada_find_extent(root, logical, top, level); /* takes one ref */
530 if (!re)
531 return -1;
532
533 rec = kzalloc(sizeof(*rec), GFP_NOFS);
534 if (!rec) {
535 reada_extent_put(root->fs_info, re);
536 return -1;
537 }
538
539 rec->rc = rc;
540 rec->generation = generation;
541 atomic_inc(&rc->elems);
542
543 spin_lock(&re->lock);
544 list_add_tail(&rec->list, &re->extctl);
545 spin_unlock(&re->lock);
546
547 /* leave the ref on the extent */
548
549 return 0;
550}
551
552/*
553 * called with fs_info->reada_lock held
554 */
555static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock)
556{
557 int i;
558 unsigned long index = zone->end >> PAGE_CACHE_SHIFT;
559
560 for (i = 0; i < zone->ndevs; ++i) {
561 struct reada_zone *peer;
562 peer = radix_tree_lookup(&zone->devs[i]->reada_zones, index);
563 if (peer && peer->device != zone->device)
564 peer->locked = lock;
565 }
566}
567
568/*
569 * called with fs_info->reada_lock held
570 */
571static int reada_pick_zone(struct btrfs_device *dev)
572{
573 struct reada_zone *top_zone = NULL;
574 struct reada_zone *top_locked_zone = NULL;
575 u64 top_elems = 0;
576 u64 top_locked_elems = 0;
577 unsigned long index = 0;
578 int ret;
579
580 if (dev->reada_curr_zone) {
581 reada_peer_zones_set_lock(dev->reada_curr_zone, 0);
582 kref_put(&dev->reada_curr_zone->refcnt, reada_zone_release);
583 dev->reada_curr_zone = NULL;
584 }
585 /* pick the zone with the most elements */
586 while (1) {
587 struct reada_zone *zone;
588
589 ret = radix_tree_gang_lookup(&dev->reada_zones,
590 (void **)&zone, index, 1);
591 if (ret == 0)
592 break;
593 index = (zone->end >> PAGE_CACHE_SHIFT) + 1;
594 if (zone->locked) {
595 if (zone->elems > top_locked_elems) {
596 top_locked_elems = zone->elems;
597 top_locked_zone = zone;
598 }
599 } else {
600 if (zone->elems > top_elems) {
601 top_elems = zone->elems;
602 top_zone = zone;
603 }
604 }
605 }
606 if (top_zone)
607 dev->reada_curr_zone = top_zone;
608 else if (top_locked_zone)
609 dev->reada_curr_zone = top_locked_zone;
610 else
611 return 0;
612
613 dev->reada_next = dev->reada_curr_zone->start;
614 kref_get(&dev->reada_curr_zone->refcnt);
615 reada_peer_zones_set_lock(dev->reada_curr_zone, 1);
616
617 return 1;
618}
619
620static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
621 struct btrfs_device *dev)
622{
623 struct reada_extent *re = NULL;
624 int mirror_num = 0;
625 struct extent_buffer *eb = NULL;
626 u64 logical;
627 u32 blocksize;
628 int ret;
629 int i;
630 int need_kick = 0;
631
632 spin_lock(&fs_info->reada_lock);
633 if (dev->reada_curr_zone == NULL) {
634 ret = reada_pick_zone(dev);
635 if (!ret) {
636 spin_unlock(&fs_info->reada_lock);
637 return 0;
638 }
639 }
640 /*
641 * FIXME currently we issue the reads one extent at a time. If we have
642 * a contiguous block of extents, we could also coagulate them or use
643 * plugging to speed things up
644 */
645 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
646 dev->reada_next >> PAGE_CACHE_SHIFT, 1);
647 if (ret == 0 || re->logical >= dev->reada_curr_zone->end) {
648 ret = reada_pick_zone(dev);
649 if (!ret) {
650 spin_unlock(&fs_info->reada_lock);
651 return 0;
652 }
653 re = NULL;
654 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
655 dev->reada_next >> PAGE_CACHE_SHIFT, 1);
656 }
657 if (ret == 0) {
658 spin_unlock(&fs_info->reada_lock);
659 return 0;
660 }
661 dev->reada_next = re->logical + re->blocksize;
662 kref_get(&re->refcnt);
663
664 spin_unlock(&fs_info->reada_lock);
665
666 /*
667 * find mirror num
668 */
669 for (i = 0; i < re->nzones; ++i) {
670 if (re->zones[i]->device == dev) {
671 mirror_num = i + 1;
672 break;
673 }
674 }
675 logical = re->logical;
676 blocksize = re->blocksize;
677
678 spin_lock(&re->lock);
679 if (re->scheduled_for == NULL) {
680 re->scheduled_for = dev;
681 need_kick = 1;
682 }
683 spin_unlock(&re->lock);
684
685 reada_extent_put(fs_info, re);
686
687 if (!need_kick)
688 return 0;
689
690 atomic_inc(&dev->reada_in_flight);
691 ret = reada_tree_block_flagged(fs_info->extent_root, logical, blocksize,
692 mirror_num, &eb);
693 if (ret)
694 __readahead_hook(fs_info->extent_root, NULL, logical, ret);
695 else if (eb)
696 __readahead_hook(fs_info->extent_root, eb, eb->start, ret);
697
698 if (eb)
699 free_extent_buffer(eb);
700
701 return 1;
702
703}
704
705static void reada_start_machine_worker(struct btrfs_work *work)
706{
707 struct reada_machine_work *rmw;
708 struct btrfs_fs_info *fs_info;
709
710 rmw = container_of(work, struct reada_machine_work, work);
711 fs_info = rmw->fs_info;
712
713 kfree(rmw);
714
715 __reada_start_machine(fs_info);
716}
717
718static void __reada_start_machine(struct btrfs_fs_info *fs_info)
719{
720 struct btrfs_device *device;
721 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
722 u64 enqueued;
723 u64 total = 0;
724 int i;
725
726 do {
727 enqueued = 0;
728 list_for_each_entry(device, &fs_devices->devices, dev_list) {
729 if (atomic_read(&device->reada_in_flight) <
730 MAX_IN_FLIGHT)
731 enqueued += reada_start_machine_dev(fs_info,
732 device);
733 }
734 total += enqueued;
735 } while (enqueued && total < 10000);
736
737 if (enqueued == 0)
738 return;
739
740 /*
741 * If everything is already in the cache, this is effectively single
742 * threaded. To a) not hold the caller for too long and b) to utilize
743 * more cores, we broke the loop above after 10000 iterations and now
744 * enqueue to workers to finish it. This will distribute the load to
745 * the cores.
746 */
747 for (i = 0; i < 2; ++i)
748 reada_start_machine(fs_info);
749}
750
751static void reada_start_machine(struct btrfs_fs_info *fs_info)
752{
753 struct reada_machine_work *rmw;
754
755 rmw = kzalloc(sizeof(*rmw), GFP_NOFS);
756 if (!rmw) {
757 /* FIXME we cannot handle this properly right now */
758 BUG();
759 }
760 rmw->work.func = reada_start_machine_worker;
761 rmw->fs_info = fs_info;
762
763 btrfs_queue_worker(&fs_info->readahead_workers, &rmw->work);
764}
765
766#ifdef DEBUG
767static void dump_devs(struct btrfs_fs_info *fs_info, int all)
768{
769 struct btrfs_device *device;
770 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
771 unsigned long index;
772 int ret;
773 int i;
774 int j;
775 int cnt;
776
777 spin_lock(&fs_info->reada_lock);
778 list_for_each_entry(device, &fs_devices->devices, dev_list) {
779 printk(KERN_DEBUG "dev %lld has %d in flight\n", device->devid,
780 atomic_read(&device->reada_in_flight));
781 index = 0;
782 while (1) {
783 struct reada_zone *zone;
784 ret = radix_tree_gang_lookup(&device->reada_zones,
785 (void **)&zone, index, 1);
786 if (ret == 0)
787 break;
788 printk(KERN_DEBUG " zone %llu-%llu elems %llu locked "
789 "%d devs", zone->start, zone->end, zone->elems,
790 zone->locked);
791 for (j = 0; j < zone->ndevs; ++j) {
792 printk(KERN_CONT " %lld",
793 zone->devs[j]->devid);
794 }
795 if (device->reada_curr_zone == zone)
796 printk(KERN_CONT " curr off %llu",
797 device->reada_next - zone->start);
798 printk(KERN_CONT "\n");
799 index = (zone->end >> PAGE_CACHE_SHIFT) + 1;
800 }
801 cnt = 0;
802 index = 0;
803 while (all) {
804 struct reada_extent *re = NULL;
805
806 ret = radix_tree_gang_lookup(&device->reada_extents,
807 (void **)&re, index, 1);
808 if (ret == 0)
809 break;
810 printk(KERN_DEBUG
811 " re: logical %llu size %u empty %d for %lld",
812 re->logical, re->blocksize,
813 list_empty(&re->extctl), re->scheduled_for ?
814 re->scheduled_for->devid : -1);
815
816 for (i = 0; i < re->nzones; ++i) {
817 printk(KERN_CONT " zone %llu-%llu devs",
818 re->zones[i]->start,
819 re->zones[i]->end);
820 for (j = 0; j < re->zones[i]->ndevs; ++j) {
821 printk(KERN_CONT " %lld",
822 re->zones[i]->devs[j]->devid);
823 }
824 }
825 printk(KERN_CONT "\n");
826 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
827 if (++cnt > 15)
828 break;
829 }
830 }
831
832 index = 0;
833 cnt = 0;
834 while (all) {
835 struct reada_extent *re = NULL;
836
837 ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re,
838 index, 1);
839 if (ret == 0)
840 break;
841 if (!re->scheduled_for) {
842 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
843 continue;
844 }
845 printk(KERN_DEBUG
846 "re: logical %llu size %u list empty %d for %lld",
847 re->logical, re->blocksize, list_empty(&re->extctl),
848 re->scheduled_for ? re->scheduled_for->devid : -1);
849 for (i = 0; i < re->nzones; ++i) {
850 printk(KERN_CONT " zone %llu-%llu devs",
851 re->zones[i]->start,
852 re->zones[i]->end);
853 for (i = 0; i < re->nzones; ++i) {
854 printk(KERN_CONT " zone %llu-%llu devs",
855 re->zones[i]->start,
856 re->zones[i]->end);
857 for (j = 0; j < re->zones[i]->ndevs; ++j) {
858 printk(KERN_CONT " %lld",
859 re->zones[i]->devs[j]->devid);
860 }
861 }
862 }
863 printk(KERN_CONT "\n");
864 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
865 }
866 spin_unlock(&fs_info->reada_lock);
867}
868#endif
869
870/*
871 * interface
872 */
873struct reada_control *btrfs_reada_add(struct btrfs_root *root,
874 struct btrfs_key *key_start, struct btrfs_key *key_end)
875{
876 struct reada_control *rc;
877 u64 start;
878 u64 generation;
879 int level;
880 struct extent_buffer *node;
881 static struct btrfs_key max_key = {
882 .objectid = (u64)-1,
883 .type = (u8)-1,
884 .offset = (u64)-1
885 };
886
887 rc = kzalloc(sizeof(*rc), GFP_NOFS);
888 if (!rc)
889 return ERR_PTR(-ENOMEM);
890
891 rc->root = root;
892 rc->key_start = *key_start;
893 rc->key_end = *key_end;
894 atomic_set(&rc->elems, 0);
895 init_waitqueue_head(&rc->wait);
896 kref_init(&rc->refcnt);
897 kref_get(&rc->refcnt); /* one ref for having elements */
898
899 node = btrfs_root_node(root);
900 start = node->start;
901 level = btrfs_header_level(node);
902 generation = btrfs_header_generation(node);
903 free_extent_buffer(node);
904
905 reada_add_block(rc, start, &max_key, level, generation);
906
907 reada_start_machine(root->fs_info);
908
909 return rc;
910}
911
912#ifdef DEBUG
913int btrfs_reada_wait(void *handle)
914{
915 struct reada_control *rc = handle;
916
917 while (atomic_read(&rc->elems)) {
918 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
919 5 * HZ);
920 dump_devs(rc->root->fs_info, rc->elems < 10 ? 1 : 0);
921 }
922
923 dump_devs(rc->root->fs_info, rc->elems < 10 ? 1 : 0);
924
925 kref_put(&rc->refcnt, reada_control_release);
926
927 return 0;
928}
929#else
930int btrfs_reada_wait(void *handle)
931{
932 struct reada_control *rc = handle;
933
934 while (atomic_read(&rc->elems)) {
935 wait_event(rc->wait, atomic_read(&rc->elems) == 0);
936 }
937
938 kref_put(&rc->refcnt, reada_control_release);
939
940 return 0;
941}
942#endif
943
944void btrfs_reada_detach(void *handle)
945{
946 struct reada_control *rc = handle;
947
948 kref_put(&rc->refcnt, reada_control_release);
949}
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-24 17:14:08 -0500