vt_ioctl: fix GIO_UNIMAP regression
[platform/kernel/linux-rpi.git] / fs / btrfs / reada.c
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 #include "block-group.h"
18
19 #undef DEBUG
20
21 /*
22  * This is the implementation for the generic read ahead framework.
23  *
24  * To trigger a readahead, btrfs_reada_add must be called. It will start
25  * a read ahead for the given range [start, end) on tree root. The returned
26  * handle can either be used to wait on the readahead to finish
27  * (btrfs_reada_wait), or to send it to the background (btrfs_reada_detach).
28  *
29  * The read ahead works as follows:
30  * On btrfs_reada_add, the root of the tree is inserted into a radix_tree.
31  * reada_start_machine will then search for extents to prefetch and trigger
32  * some reads. When a read finishes for a node, all contained node/leaf
33  * pointers that lie in the given range will also be enqueued. The reads will
34  * be triggered in sequential order, thus giving a big win over a naive
35  * enumeration. It will also make use of multi-device layouts. Each disk
36  * will have its on read pointer and all disks will by utilized in parallel.
37  * Also will no two disks read both sides of a mirror simultaneously, as this
38  * would waste seeking capacity. Instead both disks will read different parts
39  * of the filesystem.
40  * Any number of readaheads can be started in parallel. The read order will be
41  * determined globally, i.e. 2 parallel readaheads will normally finish faster
42  * than the 2 started one after another.
43  */
44
45 #define MAX_IN_FLIGHT 6
46
47 struct reada_extctl {
48         struct list_head        list;
49         struct reada_control    *rc;
50         u64                     generation;
51 };
52
53 struct reada_extent {
54         u64                     logical;
55         struct btrfs_key        top;
56         struct list_head        extctl;
57         int                     refcnt;
58         spinlock_t              lock;
59         struct reada_zone       *zones[BTRFS_MAX_MIRRORS];
60         int                     nzones;
61         int                     scheduled;
62 };
63
64 struct reada_zone {
65         u64                     start;
66         u64                     end;
67         u64                     elems;
68         struct list_head        list;
69         spinlock_t              lock;
70         int                     locked;
71         struct btrfs_device     *device;
72         struct btrfs_device     *devs[BTRFS_MAX_MIRRORS]; /* full list, incl
73                                                            * self */
74         int                     ndevs;
75         struct kref             refcnt;
76 };
77
78 struct reada_machine_work {
79         struct btrfs_work       work;
80         struct btrfs_fs_info    *fs_info;
81 };
82
83 static void reada_extent_put(struct btrfs_fs_info *, struct reada_extent *);
84 static void reada_control_release(struct kref *kref);
85 static void reada_zone_release(struct kref *kref);
86 static void reada_start_machine(struct btrfs_fs_info *fs_info);
87 static void __reada_start_machine(struct btrfs_fs_info *fs_info);
88
89 static int reada_add_block(struct reada_control *rc, u64 logical,
90                            struct btrfs_key *top, u64 generation);
91
92 /* recurses */
93 /* in case of err, eb might be NULL */
94 static void __readahead_hook(struct btrfs_fs_info *fs_info,
95                              struct reada_extent *re, struct extent_buffer *eb,
96                              int err)
97 {
98         int nritems;
99         int i;
100         u64 bytenr;
101         u64 generation;
102         struct list_head list;
103
104         spin_lock(&re->lock);
105         /*
106          * just take the full list from the extent. afterwards we
107          * don't need the lock anymore
108          */
109         list_replace_init(&re->extctl, &list);
110         re->scheduled = 0;
111         spin_unlock(&re->lock);
112
113         /*
114          * this is the error case, the extent buffer has not been
115          * read correctly. We won't access anything from it and
116          * just cleanup our data structures. Effectively this will
117          * cut the branch below this node from read ahead.
118          */
119         if (err)
120                 goto cleanup;
121
122         /*
123          * FIXME: currently we just set nritems to 0 if this is a leaf,
124          * effectively ignoring the content. In a next step we could
125          * trigger more readahead depending from the content, e.g.
126          * fetch the checksums for the extents in the leaf.
127          */
128         if (!btrfs_header_level(eb))
129                 goto cleanup;
130
131         nritems = btrfs_header_nritems(eb);
132         generation = btrfs_header_generation(eb);
133         for (i = 0; i < nritems; i++) {
134                 struct reada_extctl *rec;
135                 u64 n_gen;
136                 struct btrfs_key key;
137                 struct btrfs_key next_key;
138
139                 btrfs_node_key_to_cpu(eb, &key, i);
140                 if (i + 1 < nritems)
141                         btrfs_node_key_to_cpu(eb, &next_key, i + 1);
142                 else
143                         next_key = re->top;
144                 bytenr = btrfs_node_blockptr(eb, i);
145                 n_gen = btrfs_node_ptr_generation(eb, i);
146
147                 list_for_each_entry(rec, &list, list) {
148                         struct reada_control *rc = rec->rc;
149
150                         /*
151                          * if the generation doesn't match, just ignore this
152                          * extctl. This will probably cut off a branch from
153                          * prefetch. Alternatively one could start a new (sub-)
154                          * prefetch for this branch, starting again from root.
155                          * FIXME: move the generation check out of this loop
156                          */
157 #ifdef DEBUG
158                         if (rec->generation != generation) {
159                                 btrfs_debug(fs_info,
160                                             "generation mismatch for (%llu,%d,%llu) %llu != %llu",
161                                             key.objectid, key.type, key.offset,
162                                             rec->generation, generation);
163                         }
164 #endif
165                         if (rec->generation == generation &&
166                             btrfs_comp_cpu_keys(&key, &rc->key_end) < 0 &&
167                             btrfs_comp_cpu_keys(&next_key, &rc->key_start) > 0)
168                                 reada_add_block(rc, bytenr, &next_key, n_gen);
169                 }
170         }
171
172 cleanup:
173         /*
174          * free extctl records
175          */
176         while (!list_empty(&list)) {
177                 struct reada_control *rc;
178                 struct reada_extctl *rec;
179
180                 rec = list_first_entry(&list, struct reada_extctl, list);
181                 list_del(&rec->list);
182                 rc = rec->rc;
183                 kfree(rec);
184
185                 kref_get(&rc->refcnt);
186                 if (atomic_dec_and_test(&rc->elems)) {
187                         kref_put(&rc->refcnt, reada_control_release);
188                         wake_up(&rc->wait);
189                 }
190                 kref_put(&rc->refcnt, reada_control_release);
191
192                 reada_extent_put(fs_info, re);  /* one ref for each entry */
193         }
194
195         return;
196 }
197
198 int btree_readahead_hook(struct extent_buffer *eb, int err)
199 {
200         struct btrfs_fs_info *fs_info = eb->fs_info;
201         int ret = 0;
202         struct reada_extent *re;
203
204         /* find extent */
205         spin_lock(&fs_info->reada_lock);
206         re = radix_tree_lookup(&fs_info->reada_tree,
207                                eb->start >> PAGE_SHIFT);
208         if (re)
209                 re->refcnt++;
210         spin_unlock(&fs_info->reada_lock);
211         if (!re) {
212                 ret = -1;
213                 goto start_machine;
214         }
215
216         __readahead_hook(fs_info, re, eb, err);
217         reada_extent_put(fs_info, re);  /* our ref */
218
219 start_machine:
220         reada_start_machine(fs_info);
221         return ret;
222 }
223
224 static struct reada_zone *reada_find_zone(struct btrfs_device *dev, u64 logical,
225                                           struct btrfs_bio *bbio)
226 {
227         struct btrfs_fs_info *fs_info = dev->fs_info;
228         int ret;
229         struct reada_zone *zone;
230         struct btrfs_block_group *cache = NULL;
231         u64 start;
232         u64 end;
233         int i;
234
235         zone = NULL;
236         spin_lock(&fs_info->reada_lock);
237         ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
238                                      logical >> PAGE_SHIFT, 1);
239         if (ret == 1 && logical >= zone->start && logical <= zone->end) {
240                 kref_get(&zone->refcnt);
241                 spin_unlock(&fs_info->reada_lock);
242                 return zone;
243         }
244
245         spin_unlock(&fs_info->reada_lock);
246
247         cache = btrfs_lookup_block_group(fs_info, logical);
248         if (!cache)
249                 return NULL;
250
251         start = cache->start;
252         end = start + cache->length - 1;
253         btrfs_put_block_group(cache);
254
255         zone = kzalloc(sizeof(*zone), GFP_KERNEL);
256         if (!zone)
257                 return NULL;
258
259         ret = radix_tree_preload(GFP_KERNEL);
260         if (ret) {
261                 kfree(zone);
262                 return NULL;
263         }
264
265         zone->start = start;
266         zone->end = end;
267         INIT_LIST_HEAD(&zone->list);
268         spin_lock_init(&zone->lock);
269         zone->locked = 0;
270         kref_init(&zone->refcnt);
271         zone->elems = 0;
272         zone->device = dev; /* our device always sits at index 0 */
273         for (i = 0; i < bbio->num_stripes; ++i) {
274                 /* bounds have already been checked */
275                 zone->devs[i] = bbio->stripes[i].dev;
276         }
277         zone->ndevs = bbio->num_stripes;
278
279         spin_lock(&fs_info->reada_lock);
280         ret = radix_tree_insert(&dev->reada_zones,
281                                 (unsigned long)(zone->end >> PAGE_SHIFT),
282                                 zone);
283
284         if (ret == -EEXIST) {
285                 kfree(zone);
286                 ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
287                                              logical >> PAGE_SHIFT, 1);
288                 if (ret == 1 && logical >= zone->start && logical <= zone->end)
289                         kref_get(&zone->refcnt);
290                 else
291                         zone = NULL;
292         }
293         spin_unlock(&fs_info->reada_lock);
294         radix_tree_preload_end();
295
296         return zone;
297 }
298
299 static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info,
300                                               u64 logical,
301                                               struct btrfs_key *top)
302 {
303         int ret;
304         struct reada_extent *re = NULL;
305         struct reada_extent *re_exist = NULL;
306         struct btrfs_bio *bbio = NULL;
307         struct btrfs_device *dev;
308         struct btrfs_device *prev_dev;
309         u64 length;
310         int real_stripes;
311         int nzones = 0;
312         unsigned long index = logical >> PAGE_SHIFT;
313         int dev_replace_is_ongoing;
314         int have_zone = 0;
315
316         spin_lock(&fs_info->reada_lock);
317         re = radix_tree_lookup(&fs_info->reada_tree, index);
318         if (re)
319                 re->refcnt++;
320         spin_unlock(&fs_info->reada_lock);
321
322         if (re)
323                 return re;
324
325         re = kzalloc(sizeof(*re), GFP_KERNEL);
326         if (!re)
327                 return NULL;
328
329         re->logical = logical;
330         re->top = *top;
331         INIT_LIST_HEAD(&re->extctl);
332         spin_lock_init(&re->lock);
333         re->refcnt = 1;
334
335         /*
336          * map block
337          */
338         length = fs_info->nodesize;
339         ret = btrfs_map_block(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,
340                         &length, &bbio, 0);
341         if (ret || !bbio || length < fs_info->nodesize)
342                 goto error;
343
344         if (bbio->num_stripes > BTRFS_MAX_MIRRORS) {
345                 btrfs_err(fs_info,
346                            "readahead: more than %d copies not supported",
347                            BTRFS_MAX_MIRRORS);
348                 goto error;
349         }
350
351         real_stripes = bbio->num_stripes - bbio->num_tgtdevs;
352         for (nzones = 0; nzones < real_stripes; ++nzones) {
353                 struct reada_zone *zone;
354
355                 dev = bbio->stripes[nzones].dev;
356
357                 /* cannot read ahead on missing device. */
358                 if (!dev->bdev)
359                         continue;
360
361                 zone = reada_find_zone(dev, logical, bbio);
362                 if (!zone)
363                         continue;
364
365                 re->zones[re->nzones++] = zone;
366                 spin_lock(&zone->lock);
367                 if (!zone->elems)
368                         kref_get(&zone->refcnt);
369                 ++zone->elems;
370                 spin_unlock(&zone->lock);
371                 spin_lock(&fs_info->reada_lock);
372                 kref_put(&zone->refcnt, reada_zone_release);
373                 spin_unlock(&fs_info->reada_lock);
374         }
375         if (re->nzones == 0) {
376                 /* not a single zone found, error and out */
377                 goto error;
378         }
379
380         /* Insert extent in reada tree + all per-device trees, all or nothing */
381         down_read(&fs_info->dev_replace.rwsem);
382         ret = radix_tree_preload(GFP_KERNEL);
383         if (ret) {
384                 up_read(&fs_info->dev_replace.rwsem);
385                 goto error;
386         }
387
388         spin_lock(&fs_info->reada_lock);
389         ret = radix_tree_insert(&fs_info->reada_tree, index, re);
390         if (ret == -EEXIST) {
391                 re_exist = radix_tree_lookup(&fs_info->reada_tree, index);
392                 re_exist->refcnt++;
393                 spin_unlock(&fs_info->reada_lock);
394                 radix_tree_preload_end();
395                 up_read(&fs_info->dev_replace.rwsem);
396                 goto error;
397         }
398         if (ret) {
399                 spin_unlock(&fs_info->reada_lock);
400                 radix_tree_preload_end();
401                 up_read(&fs_info->dev_replace.rwsem);
402                 goto error;
403         }
404         radix_tree_preload_end();
405         prev_dev = NULL;
406         dev_replace_is_ongoing = btrfs_dev_replace_is_ongoing(
407                         &fs_info->dev_replace);
408         for (nzones = 0; nzones < re->nzones; ++nzones) {
409                 dev = re->zones[nzones]->device;
410
411                 if (dev == prev_dev) {
412                         /*
413                          * in case of DUP, just add the first zone. As both
414                          * are on the same device, there's nothing to gain
415                          * from adding both.
416                          * Also, it wouldn't work, as the tree is per device
417                          * and adding would fail with EEXIST
418                          */
419                         continue;
420                 }
421                 if (!dev->bdev)
422                         continue;
423
424                 if (dev_replace_is_ongoing &&
425                     dev == fs_info->dev_replace.tgtdev) {
426                         /*
427                          * as this device is selected for reading only as
428                          * a last resort, skip it for read ahead.
429                          */
430                         continue;
431                 }
432                 prev_dev = dev;
433                 ret = radix_tree_insert(&dev->reada_extents, index, re);
434                 if (ret) {
435                         while (--nzones >= 0) {
436                                 dev = re->zones[nzones]->device;
437                                 BUG_ON(dev == NULL);
438                                 /* ignore whether the entry was inserted */
439                                 radix_tree_delete(&dev->reada_extents, index);
440                         }
441                         radix_tree_delete(&fs_info->reada_tree, index);
442                         spin_unlock(&fs_info->reada_lock);
443                         up_read(&fs_info->dev_replace.rwsem);
444                         goto error;
445                 }
446                 have_zone = 1;
447         }
448         spin_unlock(&fs_info->reada_lock);
449         up_read(&fs_info->dev_replace.rwsem);
450
451         if (!have_zone)
452                 goto error;
453
454         btrfs_put_bbio(bbio);
455         return re;
456
457 error:
458         for (nzones = 0; nzones < re->nzones; ++nzones) {
459                 struct reada_zone *zone;
460
461                 zone = re->zones[nzones];
462                 kref_get(&zone->refcnt);
463                 spin_lock(&zone->lock);
464                 --zone->elems;
465                 if (zone->elems == 0) {
466                         /*
467                          * no fs_info->reada_lock needed, as this can't be
468                          * the last ref
469                          */
470                         kref_put(&zone->refcnt, reada_zone_release);
471                 }
472                 spin_unlock(&zone->lock);
473
474                 spin_lock(&fs_info->reada_lock);
475                 kref_put(&zone->refcnt, reada_zone_release);
476                 spin_unlock(&fs_info->reada_lock);
477         }
478         btrfs_put_bbio(bbio);
479         kfree(re);
480         return re_exist;
481 }
482
483 static void reada_extent_put(struct btrfs_fs_info *fs_info,
484                              struct reada_extent *re)
485 {
486         int i;
487         unsigned long index = re->logical >> PAGE_SHIFT;
488
489         spin_lock(&fs_info->reada_lock);
490         if (--re->refcnt) {
491                 spin_unlock(&fs_info->reada_lock);
492                 return;
493         }
494
495         radix_tree_delete(&fs_info->reada_tree, index);
496         for (i = 0; i < re->nzones; ++i) {
497                 struct reada_zone *zone = re->zones[i];
498
499                 radix_tree_delete(&zone->device->reada_extents, index);
500         }
501
502         spin_unlock(&fs_info->reada_lock);
503
504         for (i = 0; i < re->nzones; ++i) {
505                 struct reada_zone *zone = re->zones[i];
506
507                 kref_get(&zone->refcnt);
508                 spin_lock(&zone->lock);
509                 --zone->elems;
510                 if (zone->elems == 0) {
511                         /* no fs_info->reada_lock needed, as this can't be
512                          * the last ref */
513                         kref_put(&zone->refcnt, reada_zone_release);
514                 }
515                 spin_unlock(&zone->lock);
516
517                 spin_lock(&fs_info->reada_lock);
518                 kref_put(&zone->refcnt, reada_zone_release);
519                 spin_unlock(&fs_info->reada_lock);
520         }
521
522         kfree(re);
523 }
524
525 static void reada_zone_release(struct kref *kref)
526 {
527         struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt);
528
529         radix_tree_delete(&zone->device->reada_zones,
530                           zone->end >> PAGE_SHIFT);
531
532         kfree(zone);
533 }
534
535 static void reada_control_release(struct kref *kref)
536 {
537         struct reada_control *rc = container_of(kref, struct reada_control,
538                                                 refcnt);
539
540         kfree(rc);
541 }
542
543 static int reada_add_block(struct reada_control *rc, u64 logical,
544                            struct btrfs_key *top, u64 generation)
545 {
546         struct btrfs_fs_info *fs_info = rc->fs_info;
547         struct reada_extent *re;
548         struct reada_extctl *rec;
549
550         /* takes one ref */
551         re = reada_find_extent(fs_info, logical, top);
552         if (!re)
553                 return -1;
554
555         rec = kzalloc(sizeof(*rec), GFP_KERNEL);
556         if (!rec) {
557                 reada_extent_put(fs_info, re);
558                 return -ENOMEM;
559         }
560
561         rec->rc = rc;
562         rec->generation = generation;
563         atomic_inc(&rc->elems);
564
565         spin_lock(&re->lock);
566         list_add_tail(&rec->list, &re->extctl);
567         spin_unlock(&re->lock);
568
569         /* leave the ref on the extent */
570
571         return 0;
572 }
573
574 /*
575  * called with fs_info->reada_lock held
576  */
577 static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock)
578 {
579         int i;
580         unsigned long index = zone->end >> PAGE_SHIFT;
581
582         for (i = 0; i < zone->ndevs; ++i) {
583                 struct reada_zone *peer;
584                 peer = radix_tree_lookup(&zone->devs[i]->reada_zones, index);
585                 if (peer && peer->device != zone->device)
586                         peer->locked = lock;
587         }
588 }
589
590 /*
591  * called with fs_info->reada_lock held
592  */
593 static int reada_pick_zone(struct btrfs_device *dev)
594 {
595         struct reada_zone *top_zone = NULL;
596         struct reada_zone *top_locked_zone = NULL;
597         u64 top_elems = 0;
598         u64 top_locked_elems = 0;
599         unsigned long index = 0;
600         int ret;
601
602         if (dev->reada_curr_zone) {
603                 reada_peer_zones_set_lock(dev->reada_curr_zone, 0);
604                 kref_put(&dev->reada_curr_zone->refcnt, reada_zone_release);
605                 dev->reada_curr_zone = NULL;
606         }
607         /* pick the zone with the most elements */
608         while (1) {
609                 struct reada_zone *zone;
610
611                 ret = radix_tree_gang_lookup(&dev->reada_zones,
612                                              (void **)&zone, index, 1);
613                 if (ret == 0)
614                         break;
615                 index = (zone->end >> PAGE_SHIFT) + 1;
616                 if (zone->locked) {
617                         if (zone->elems > top_locked_elems) {
618                                 top_locked_elems = zone->elems;
619                                 top_locked_zone = zone;
620                         }
621                 } else {
622                         if (zone->elems > top_elems) {
623                                 top_elems = zone->elems;
624                                 top_zone = zone;
625                         }
626                 }
627         }
628         if (top_zone)
629                 dev->reada_curr_zone = top_zone;
630         else if (top_locked_zone)
631                 dev->reada_curr_zone = top_locked_zone;
632         else
633                 return 0;
634
635         dev->reada_next = dev->reada_curr_zone->start;
636         kref_get(&dev->reada_curr_zone->refcnt);
637         reada_peer_zones_set_lock(dev->reada_curr_zone, 1);
638
639         return 1;
640 }
641
642 static int reada_tree_block_flagged(struct btrfs_fs_info *fs_info, u64 bytenr,
643                                     int mirror_num, struct extent_buffer **eb)
644 {
645         struct extent_buffer *buf = NULL;
646         int ret;
647
648         buf = btrfs_find_create_tree_block(fs_info, bytenr);
649         if (IS_ERR(buf))
650                 return 0;
651
652         set_bit(EXTENT_BUFFER_READAHEAD, &buf->bflags);
653
654         ret = read_extent_buffer_pages(buf, WAIT_PAGE_LOCK, mirror_num);
655         if (ret) {
656                 free_extent_buffer_stale(buf);
657                 return ret;
658         }
659
660         if (test_bit(EXTENT_BUFFER_CORRUPT, &buf->bflags)) {
661                 free_extent_buffer_stale(buf);
662                 return -EIO;
663         } else if (extent_buffer_uptodate(buf)) {
664                 *eb = buf;
665         } else {
666                 free_extent_buffer(buf);
667         }
668         return 0;
669 }
670
671 static int reada_start_machine_dev(struct btrfs_device *dev)
672 {
673         struct btrfs_fs_info *fs_info = dev->fs_info;
674         struct reada_extent *re = NULL;
675         int mirror_num = 0;
676         struct extent_buffer *eb = NULL;
677         u64 logical;
678         int ret;
679         int i;
680
681         spin_lock(&fs_info->reada_lock);
682         if (dev->reada_curr_zone == NULL) {
683                 ret = reada_pick_zone(dev);
684                 if (!ret) {
685                         spin_unlock(&fs_info->reada_lock);
686                         return 0;
687                 }
688         }
689         /*
690          * FIXME currently we issue the reads one extent at a time. If we have
691          * a contiguous block of extents, we could also coagulate them or use
692          * plugging to speed things up
693          */
694         ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
695                                      dev->reada_next >> PAGE_SHIFT, 1);
696         if (ret == 0 || re->logical > dev->reada_curr_zone->end) {
697                 ret = reada_pick_zone(dev);
698                 if (!ret) {
699                         spin_unlock(&fs_info->reada_lock);
700                         return 0;
701                 }
702                 re = NULL;
703                 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
704                                         dev->reada_next >> PAGE_SHIFT, 1);
705         }
706         if (ret == 0) {
707                 spin_unlock(&fs_info->reada_lock);
708                 return 0;
709         }
710         dev->reada_next = re->logical + fs_info->nodesize;
711         re->refcnt++;
712
713         spin_unlock(&fs_info->reada_lock);
714
715         spin_lock(&re->lock);
716         if (re->scheduled || list_empty(&re->extctl)) {
717                 spin_unlock(&re->lock);
718                 reada_extent_put(fs_info, re);
719                 return 0;
720         }
721         re->scheduled = 1;
722         spin_unlock(&re->lock);
723
724         /*
725          * find mirror num
726          */
727         for (i = 0; i < re->nzones; ++i) {
728                 if (re->zones[i]->device == dev) {
729                         mirror_num = i + 1;
730                         break;
731                 }
732         }
733         logical = re->logical;
734
735         atomic_inc(&dev->reada_in_flight);
736         ret = reada_tree_block_flagged(fs_info, logical, mirror_num, &eb);
737         if (ret)
738                 __readahead_hook(fs_info, re, NULL, ret);
739         else if (eb)
740                 __readahead_hook(fs_info, re, eb, ret);
741
742         if (eb)
743                 free_extent_buffer(eb);
744
745         atomic_dec(&dev->reada_in_flight);
746         reada_extent_put(fs_info, re);
747
748         return 1;
749
750 }
751
752 static void reada_start_machine_worker(struct btrfs_work *work)
753 {
754         struct reada_machine_work *rmw;
755         int old_ioprio;
756
757         rmw = container_of(work, struct reada_machine_work, work);
758
759         old_ioprio = IOPRIO_PRIO_VALUE(task_nice_ioclass(current),
760                                        task_nice_ioprio(current));
761         set_task_ioprio(current, BTRFS_IOPRIO_READA);
762         __reada_start_machine(rmw->fs_info);
763         set_task_ioprio(current, old_ioprio);
764
765         atomic_dec(&rmw->fs_info->reada_works_cnt);
766
767         kfree(rmw);
768 }
769
770 /* Try to start up to 10k READA requests for a group of devices */
771 static int reada_start_for_fsdevs(struct btrfs_fs_devices *fs_devices)
772 {
773         u64 enqueued;
774         u64 total = 0;
775         struct btrfs_device *device;
776
777         do {
778                 enqueued = 0;
779                 list_for_each_entry(device, &fs_devices->devices, dev_list) {
780                         if (atomic_read(&device->reada_in_flight) <
781                             MAX_IN_FLIGHT)
782                                 enqueued += reada_start_machine_dev(device);
783                 }
784                 total += enqueued;
785         } while (enqueued && total < 10000);
786
787         return total;
788 }
789
790 static void __reada_start_machine(struct btrfs_fs_info *fs_info)
791 {
792         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices, *seed_devs;
793         int i;
794         u64 enqueued = 0;
795
796         mutex_lock(&fs_devices->device_list_mutex);
797
798         enqueued += reada_start_for_fsdevs(fs_devices);
799         list_for_each_entry(seed_devs, &fs_devices->seed_list, seed_list)
800                 enqueued += reada_start_for_fsdevs(seed_devs);
801
802         mutex_unlock(&fs_devices->device_list_mutex);
803         if (enqueued == 0)
804                 return;
805
806         /*
807          * If everything is already in the cache, this is effectively single
808          * threaded. To a) not hold the caller for too long and b) to utilize
809          * more cores, we broke the loop above after 10000 iterations and now
810          * enqueue to workers to finish it. This will distribute the load to
811          * the cores.
812          */
813         for (i = 0; i < 2; ++i) {
814                 reada_start_machine(fs_info);
815                 if (atomic_read(&fs_info->reada_works_cnt) >
816                     BTRFS_MAX_MIRRORS * 2)
817                         break;
818         }
819 }
820
821 static void reada_start_machine(struct btrfs_fs_info *fs_info)
822 {
823         struct reada_machine_work *rmw;
824
825         rmw = kzalloc(sizeof(*rmw), GFP_KERNEL);
826         if (!rmw) {
827                 /* FIXME we cannot handle this properly right now */
828                 BUG();
829         }
830         btrfs_init_work(&rmw->work, reada_start_machine_worker, NULL, NULL);
831         rmw->fs_info = fs_info;
832
833         btrfs_queue_work(fs_info->readahead_workers, &rmw->work);
834         atomic_inc(&fs_info->reada_works_cnt);
835 }
836
837 #ifdef DEBUG
838 static void dump_devs(struct btrfs_fs_info *fs_info, int all)
839 {
840         struct btrfs_device *device;
841         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
842         unsigned long index;
843         int ret;
844         int i;
845         int j;
846         int cnt;
847
848         spin_lock(&fs_info->reada_lock);
849         list_for_each_entry(device, &fs_devices->devices, dev_list) {
850                 btrfs_debug(fs_info, "dev %lld has %d in flight", device->devid,
851                         atomic_read(&device->reada_in_flight));
852                 index = 0;
853                 while (1) {
854                         struct reada_zone *zone;
855                         ret = radix_tree_gang_lookup(&device->reada_zones,
856                                                      (void **)&zone, index, 1);
857                         if (ret == 0)
858                                 break;
859                         pr_debug("  zone %llu-%llu elems %llu locked %d devs",
860                                     zone->start, zone->end, zone->elems,
861                                     zone->locked);
862                         for (j = 0; j < zone->ndevs; ++j) {
863                                 pr_cont(" %lld",
864                                         zone->devs[j]->devid);
865                         }
866                         if (device->reada_curr_zone == zone)
867                                 pr_cont(" curr off %llu",
868                                         device->reada_next - zone->start);
869                         pr_cont("\n");
870                         index = (zone->end >> PAGE_SHIFT) + 1;
871                 }
872                 cnt = 0;
873                 index = 0;
874                 while (all) {
875                         struct reada_extent *re = NULL;
876
877                         ret = radix_tree_gang_lookup(&device->reada_extents,
878                                                      (void **)&re, index, 1);
879                         if (ret == 0)
880                                 break;
881                         pr_debug("  re: logical %llu size %u empty %d scheduled %d",
882                                 re->logical, fs_info->nodesize,
883                                 list_empty(&re->extctl), re->scheduled);
884
885                         for (i = 0; i < re->nzones; ++i) {
886                                 pr_cont(" zone %llu-%llu devs",
887                                         re->zones[i]->start,
888                                         re->zones[i]->end);
889                                 for (j = 0; j < re->zones[i]->ndevs; ++j) {
890                                         pr_cont(" %lld",
891                                                 re->zones[i]->devs[j]->devid);
892                                 }
893                         }
894                         pr_cont("\n");
895                         index = (re->logical >> PAGE_SHIFT) + 1;
896                         if (++cnt > 15)
897                                 break;
898                 }
899         }
900
901         index = 0;
902         cnt = 0;
903         while (all) {
904                 struct reada_extent *re = NULL;
905
906                 ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re,
907                                              index, 1);
908                 if (ret == 0)
909                         break;
910                 if (!re->scheduled) {
911                         index = (re->logical >> PAGE_SHIFT) + 1;
912                         continue;
913                 }
914                 pr_debug("re: logical %llu size %u list empty %d scheduled %d",
915                         re->logical, fs_info->nodesize,
916                         list_empty(&re->extctl), re->scheduled);
917                 for (i = 0; i < re->nzones; ++i) {
918                         pr_cont(" zone %llu-%llu devs",
919                                 re->zones[i]->start,
920                                 re->zones[i]->end);
921                         for (j = 0; j < re->zones[i]->ndevs; ++j) {
922                                 pr_cont(" %lld",
923                                        re->zones[i]->devs[j]->devid);
924                         }
925                 }
926                 pr_cont("\n");
927                 index = (re->logical >> PAGE_SHIFT) + 1;
928         }
929         spin_unlock(&fs_info->reada_lock);
930 }
931 #endif
932
933 /*
934  * interface
935  */
936 struct reada_control *btrfs_reada_add(struct btrfs_root *root,
937                         struct btrfs_key *key_start, struct btrfs_key *key_end)
938 {
939         struct reada_control *rc;
940         u64 start;
941         u64 generation;
942         int ret;
943         struct extent_buffer *node;
944         static struct btrfs_key max_key = {
945                 .objectid = (u64)-1,
946                 .type = (u8)-1,
947                 .offset = (u64)-1
948         };
949
950         rc = kzalloc(sizeof(*rc), GFP_KERNEL);
951         if (!rc)
952                 return ERR_PTR(-ENOMEM);
953
954         rc->fs_info = root->fs_info;
955         rc->key_start = *key_start;
956         rc->key_end = *key_end;
957         atomic_set(&rc->elems, 0);
958         init_waitqueue_head(&rc->wait);
959         kref_init(&rc->refcnt);
960         kref_get(&rc->refcnt); /* one ref for having elements */
961
962         node = btrfs_root_node(root);
963         start = node->start;
964         generation = btrfs_header_generation(node);
965         free_extent_buffer(node);
966
967         ret = reada_add_block(rc, start, &max_key, generation);
968         if (ret) {
969                 kfree(rc);
970                 return ERR_PTR(ret);
971         }
972
973         reada_start_machine(root->fs_info);
974
975         return rc;
976 }
977
978 #ifdef DEBUG
979 int btrfs_reada_wait(void *handle)
980 {
981         struct reada_control *rc = handle;
982         struct btrfs_fs_info *fs_info = rc->fs_info;
983
984         while (atomic_read(&rc->elems)) {
985                 if (!atomic_read(&fs_info->reada_works_cnt))
986                         reada_start_machine(fs_info);
987                 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
988                                    5 * HZ);
989                 dump_devs(fs_info, atomic_read(&rc->elems) < 10 ? 1 : 0);
990         }
991
992         dump_devs(fs_info, atomic_read(&rc->elems) < 10 ? 1 : 0);
993
994         kref_put(&rc->refcnt, reada_control_release);
995
996         return 0;
997 }
998 #else
999 int btrfs_reada_wait(void *handle)
1000 {
1001         struct reada_control *rc = handle;
1002         struct btrfs_fs_info *fs_info = rc->fs_info;
1003
1004         while (atomic_read(&rc->elems)) {
1005                 if (!atomic_read(&fs_info->reada_works_cnt))
1006                         reada_start_machine(fs_info);
1007                 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
1008                                    (HZ + 9) / 10);
1009         }
1010
1011         kref_put(&rc->refcnt, reada_control_release);
1012
1013         return 0;
1014 }
1015 #endif
1016
1017 void btrfs_reada_detach(void *handle)
1018 {
1019         struct reada_control *rc = handle;
1020
1021         kref_put(&rc->refcnt, reada_control_release);
1022 }