2 * Copyright (C) 2011 STRATO. All rights reserved.
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.
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.
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.
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>
29 #include "transaction.h"
30 #include "dev-replace.h"
35 * This is the implementation for the generic read ahead framework.
37 * To trigger a readahead, btrfs_reada_add must be called. It will start
38 * a read ahead for the given range [start, end) on tree root. The returned
39 * handle can either be used to wait on the readahead to finish
40 * (btrfs_reada_wait), or to send it to the background (btrfs_reada_detach).
42 * The read ahead works as follows:
43 * On btrfs_reada_add, the root of the tree is inserted into a radix_tree.
44 * reada_start_machine will then search for extents to prefetch and trigger
45 * some reads. When a read finishes for a node, all contained node/leaf
46 * pointers that lie in the given range will also be enqueued. The reads will
47 * be triggered in sequential order, thus giving a big win over a naive
48 * enumeration. It will also make use of multi-device layouts. Each disk
49 * will have its on read pointer and all disks will by utilized in parallel.
50 * Also will no two disks read both sides of a mirror simultaneously, as this
51 * would waste seeking capacity. Instead both disks will read different parts
53 * Any number of readaheads can be started in parallel. The read order will be
54 * determined globally, i.e. 2 parallel readaheads will normally finish faster
55 * than the 2 started one after another.
58 #define MAX_IN_FLIGHT 6
61 struct list_head list;
62 struct reada_control *rc;
70 struct list_head extctl;
73 struct reada_zone *zones[BTRFS_MAX_MIRRORS];
82 struct list_head list;
85 struct btrfs_device *device;
86 struct btrfs_device *devs[BTRFS_MAX_MIRRORS]; /* full list, incl
92 struct reada_machine_work {
93 struct btrfs_work work;
94 struct btrfs_fs_info *fs_info;
97 static void reada_extent_put(struct btrfs_fs_info *, struct reada_extent *);
98 static void reada_control_release(struct kref *kref);
99 static void reada_zone_release(struct kref *kref);
100 static void reada_start_machine(struct btrfs_fs_info *fs_info);
101 static void __reada_start_machine(struct btrfs_fs_info *fs_info);
103 static int reada_add_block(struct reada_control *rc, u64 logical,
104 struct btrfs_key *top, u64 generation);
107 /* in case of err, eb might be NULL */
108 static void __readahead_hook(struct btrfs_fs_info *fs_info,
109 struct reada_extent *re, struct extent_buffer *eb,
117 struct list_head list;
120 level = btrfs_header_level(eb);
122 spin_lock(&re->lock);
124 * just take the full list from the extent. afterwards we
125 * don't need the lock anymore
127 list_replace_init(&re->extctl, &list);
129 spin_unlock(&re->lock);
132 * this is the error case, the extent buffer has not been
133 * read correctly. We won't access anything from it and
134 * just cleanup our data structures. Effectively this will
135 * cut the branch below this node from read ahead.
141 * FIXME: currently we just set nritems to 0 if this is a leaf,
142 * effectively ignoring the content. In a next step we could
143 * trigger more readahead depending from the content, e.g.
144 * fetch the checksums for the extents in the leaf.
149 nritems = btrfs_header_nritems(eb);
150 generation = btrfs_header_generation(eb);
151 for (i = 0; i < nritems; i++) {
152 struct reada_extctl *rec;
154 struct btrfs_key key;
155 struct btrfs_key next_key;
157 btrfs_node_key_to_cpu(eb, &key, i);
159 btrfs_node_key_to_cpu(eb, &next_key, i + 1);
162 bytenr = btrfs_node_blockptr(eb, i);
163 n_gen = btrfs_node_ptr_generation(eb, i);
165 list_for_each_entry(rec, &list, list) {
166 struct reada_control *rc = rec->rc;
169 * if the generation doesn't match, just ignore this
170 * extctl. This will probably cut off a branch from
171 * prefetch. Alternatively one could start a new (sub-)
172 * prefetch for this branch, starting again from root.
173 * FIXME: move the generation check out of this loop
176 if (rec->generation != generation) {
178 "generation mismatch for (%llu,%d,%llu) %llu != %llu",
179 key.objectid, key.type, key.offset,
180 rec->generation, generation);
183 if (rec->generation == generation &&
184 btrfs_comp_cpu_keys(&key, &rc->key_end) < 0 &&
185 btrfs_comp_cpu_keys(&next_key, &rc->key_start) > 0)
186 reada_add_block(rc, bytenr, &next_key, n_gen);
192 * free extctl records
194 while (!list_empty(&list)) {
195 struct reada_control *rc;
196 struct reada_extctl *rec;
198 rec = list_first_entry(&list, struct reada_extctl, list);
199 list_del(&rec->list);
203 kref_get(&rc->refcnt);
204 if (atomic_dec_and_test(&rc->elems)) {
205 kref_put(&rc->refcnt, reada_control_release);
208 kref_put(&rc->refcnt, reada_control_release);
210 reada_extent_put(fs_info, re); /* one ref for each entry */
217 * start is passed separately in case eb in NULL, which may be the case with
220 int btree_readahead_hook(struct btrfs_fs_info *fs_info,
221 struct extent_buffer *eb, u64 start, int err)
224 struct reada_extent *re;
227 spin_lock(&fs_info->reada_lock);
228 re = radix_tree_lookup(&fs_info->reada_tree,
229 start >> PAGE_SHIFT);
232 spin_unlock(&fs_info->reada_lock);
238 __readahead_hook(fs_info, re, eb, start, err);
239 reada_extent_put(fs_info, re); /* our ref */
242 reada_start_machine(fs_info);
246 static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
247 struct btrfs_device *dev, u64 logical,
248 struct btrfs_bio *bbio)
251 struct reada_zone *zone;
252 struct btrfs_block_group_cache *cache = NULL;
258 spin_lock(&fs_info->reada_lock);
259 ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
260 logical >> PAGE_SHIFT, 1);
261 if (ret == 1 && logical >= zone->start && logical <= zone->end) {
262 kref_get(&zone->refcnt);
263 spin_unlock(&fs_info->reada_lock);
267 spin_unlock(&fs_info->reada_lock);
269 cache = btrfs_lookup_block_group(fs_info, logical);
273 start = cache->key.objectid;
274 end = start + cache->key.offset - 1;
275 btrfs_put_block_group(cache);
277 zone = kzalloc(sizeof(*zone), GFP_KERNEL);
283 INIT_LIST_HEAD(&zone->list);
284 spin_lock_init(&zone->lock);
286 kref_init(&zone->refcnt);
288 zone->device = dev; /* our device always sits at index 0 */
289 for (i = 0; i < bbio->num_stripes; ++i) {
290 /* bounds have already been checked */
291 zone->devs[i] = bbio->stripes[i].dev;
293 zone->ndevs = bbio->num_stripes;
295 spin_lock(&fs_info->reada_lock);
296 ret = radix_tree_insert(&dev->reada_zones,
297 (unsigned long)(zone->end >> PAGE_SHIFT),
300 if (ret == -EEXIST) {
302 ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
303 logical >> PAGE_SHIFT, 1);
304 if (ret == 1 && logical >= zone->start && logical <= zone->end)
305 kref_get(&zone->refcnt);
309 spin_unlock(&fs_info->reada_lock);
314 static struct reada_extent *reada_find_extent(struct btrfs_root *root,
316 struct btrfs_key *top)
319 struct reada_extent *re = NULL;
320 struct reada_extent *re_exist = NULL;
321 struct btrfs_fs_info *fs_info = root->fs_info;
322 struct btrfs_bio *bbio = NULL;
323 struct btrfs_device *dev;
324 struct btrfs_device *prev_dev;
329 unsigned long index = logical >> PAGE_SHIFT;
330 int dev_replace_is_ongoing;
333 spin_lock(&fs_info->reada_lock);
334 re = radix_tree_lookup(&fs_info->reada_tree, index);
337 spin_unlock(&fs_info->reada_lock);
342 re = kzalloc(sizeof(*re), GFP_KERNEL);
346 blocksize = root->nodesize;
347 re->logical = logical;
349 INIT_LIST_HEAD(&re->extctl);
350 spin_lock_init(&re->lock);
357 ret = btrfs_map_block(fs_info, REQ_GET_READ_MIRRORS, logical, &length,
359 if (ret || !bbio || length < blocksize)
362 if (bbio->num_stripes > BTRFS_MAX_MIRRORS) {
363 btrfs_err(root->fs_info,
364 "readahead: more than %d copies not supported",
369 real_stripes = bbio->num_stripes - bbio->num_tgtdevs;
370 for (nzones = 0; nzones < real_stripes; ++nzones) {
371 struct reada_zone *zone;
373 dev = bbio->stripes[nzones].dev;
375 /* cannot read ahead on missing device. */
379 zone = reada_find_zone(fs_info, dev, logical, bbio);
383 re->zones[re->nzones++] = zone;
384 spin_lock(&zone->lock);
386 kref_get(&zone->refcnt);
388 spin_unlock(&zone->lock);
389 spin_lock(&fs_info->reada_lock);
390 kref_put(&zone->refcnt, reada_zone_release);
391 spin_unlock(&fs_info->reada_lock);
393 if (re->nzones == 0) {
394 /* not a single zone found, error and out */
398 /* insert extent in reada_tree + all per-device trees, all or nothing */
399 btrfs_dev_replace_lock(&fs_info->dev_replace, 0);
400 spin_lock(&fs_info->reada_lock);
401 ret = radix_tree_insert(&fs_info->reada_tree, index, re);
402 if (ret == -EEXIST) {
403 re_exist = radix_tree_lookup(&fs_info->reada_tree, index);
406 spin_unlock(&fs_info->reada_lock);
407 btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
411 spin_unlock(&fs_info->reada_lock);
412 btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
416 dev_replace_is_ongoing = btrfs_dev_replace_is_ongoing(
417 &fs_info->dev_replace);
418 for (nzones = 0; nzones < re->nzones; ++nzones) {
419 dev = re->zones[nzones]->device;
421 if (dev == prev_dev) {
423 * in case of DUP, just add the first zone. As both
424 * are on the same device, there's nothing to gain
426 * Also, it wouldn't work, as the tree is per device
427 * and adding would fail with EEXIST
434 if (dev_replace_is_ongoing &&
435 dev == fs_info->dev_replace.tgtdev) {
437 * as this device is selected for reading only as
438 * a last resort, skip it for read ahead.
443 ret = radix_tree_insert(&dev->reada_extents, index, re);
445 while (--nzones >= 0) {
446 dev = re->zones[nzones]->device;
448 /* ignore whether the entry was inserted */
449 radix_tree_delete(&dev->reada_extents, index);
451 BUG_ON(fs_info == NULL);
452 radix_tree_delete(&fs_info->reada_tree, index);
453 spin_unlock(&fs_info->reada_lock);
454 btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
459 spin_unlock(&fs_info->reada_lock);
460 btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
465 btrfs_put_bbio(bbio);
469 for (nzones = 0; nzones < re->nzones; ++nzones) {
470 struct reada_zone *zone;
472 zone = re->zones[nzones];
473 kref_get(&zone->refcnt);
474 spin_lock(&zone->lock);
476 if (zone->elems == 0) {
478 * no fs_info->reada_lock needed, as this can't be
481 kref_put(&zone->refcnt, reada_zone_release);
483 spin_unlock(&zone->lock);
485 spin_lock(&fs_info->reada_lock);
486 kref_put(&zone->refcnt, reada_zone_release);
487 spin_unlock(&fs_info->reada_lock);
489 btrfs_put_bbio(bbio);
494 static void reada_extent_put(struct btrfs_fs_info *fs_info,
495 struct reada_extent *re)
498 unsigned long index = re->logical >> PAGE_SHIFT;
500 spin_lock(&fs_info->reada_lock);
502 spin_unlock(&fs_info->reada_lock);
506 radix_tree_delete(&fs_info->reada_tree, index);
507 for (i = 0; i < re->nzones; ++i) {
508 struct reada_zone *zone = re->zones[i];
510 radix_tree_delete(&zone->device->reada_extents, index);
513 spin_unlock(&fs_info->reada_lock);
515 for (i = 0; i < re->nzones; ++i) {
516 struct reada_zone *zone = re->zones[i];
518 kref_get(&zone->refcnt);
519 spin_lock(&zone->lock);
521 if (zone->elems == 0) {
522 /* no fs_info->reada_lock needed, as this can't be
524 kref_put(&zone->refcnt, reada_zone_release);
526 spin_unlock(&zone->lock);
528 spin_lock(&fs_info->reada_lock);
529 kref_put(&zone->refcnt, reada_zone_release);
530 spin_unlock(&fs_info->reada_lock);
536 static void reada_zone_release(struct kref *kref)
538 struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt);
540 radix_tree_delete(&zone->device->reada_zones,
541 zone->end >> PAGE_SHIFT);
546 static void reada_control_release(struct kref *kref)
548 struct reada_control *rc = container_of(kref, struct reada_control,
554 static int reada_add_block(struct reada_control *rc, u64 logical,
555 struct btrfs_key *top, u64 generation)
557 struct btrfs_root *root = rc->root;
558 struct reada_extent *re;
559 struct reada_extctl *rec;
561 re = reada_find_extent(root, logical, top); /* takes one ref */
565 rec = kzalloc(sizeof(*rec), GFP_KERNEL);
567 reada_extent_put(root->fs_info, re);
572 rec->generation = generation;
573 atomic_inc(&rc->elems);
575 spin_lock(&re->lock);
576 list_add_tail(&rec->list, &re->extctl);
577 spin_unlock(&re->lock);
579 /* leave the ref on the extent */
585 * called with fs_info->reada_lock held
587 static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock)
590 unsigned long index = zone->end >> PAGE_SHIFT;
592 for (i = 0; i < zone->ndevs; ++i) {
593 struct reada_zone *peer;
594 peer = radix_tree_lookup(&zone->devs[i]->reada_zones, index);
595 if (peer && peer->device != zone->device)
601 * called with fs_info->reada_lock held
603 static int reada_pick_zone(struct btrfs_device *dev)
605 struct reada_zone *top_zone = NULL;
606 struct reada_zone *top_locked_zone = NULL;
608 u64 top_locked_elems = 0;
609 unsigned long index = 0;
612 if (dev->reada_curr_zone) {
613 reada_peer_zones_set_lock(dev->reada_curr_zone, 0);
614 kref_put(&dev->reada_curr_zone->refcnt, reada_zone_release);
615 dev->reada_curr_zone = NULL;
617 /* pick the zone with the most elements */
619 struct reada_zone *zone;
621 ret = radix_tree_gang_lookup(&dev->reada_zones,
622 (void **)&zone, index, 1);
625 index = (zone->end >> PAGE_SHIFT) + 1;
627 if (zone->elems > top_locked_elems) {
628 top_locked_elems = zone->elems;
629 top_locked_zone = zone;
632 if (zone->elems > top_elems) {
633 top_elems = zone->elems;
639 dev->reada_curr_zone = top_zone;
640 else if (top_locked_zone)
641 dev->reada_curr_zone = top_locked_zone;
645 dev->reada_next = dev->reada_curr_zone->start;
646 kref_get(&dev->reada_curr_zone->refcnt);
647 reada_peer_zones_set_lock(dev->reada_curr_zone, 1);
652 static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
653 struct btrfs_device *dev)
655 struct reada_extent *re = NULL;
657 struct extent_buffer *eb = NULL;
662 spin_lock(&fs_info->reada_lock);
663 if (dev->reada_curr_zone == NULL) {
664 ret = reada_pick_zone(dev);
666 spin_unlock(&fs_info->reada_lock);
671 * FIXME currently we issue the reads one extent at a time. If we have
672 * a contiguous block of extents, we could also coagulate them or use
673 * plugging to speed things up
675 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
676 dev->reada_next >> PAGE_SHIFT, 1);
677 if (ret == 0 || re->logical > dev->reada_curr_zone->end) {
678 ret = reada_pick_zone(dev);
680 spin_unlock(&fs_info->reada_lock);
684 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
685 dev->reada_next >> PAGE_SHIFT, 1);
688 spin_unlock(&fs_info->reada_lock);
691 dev->reada_next = re->logical + fs_info->tree_root->nodesize;
694 spin_unlock(&fs_info->reada_lock);
696 spin_lock(&re->lock);
697 if (re->scheduled || list_empty(&re->extctl)) {
698 spin_unlock(&re->lock);
699 reada_extent_put(fs_info, re);
703 spin_unlock(&re->lock);
708 for (i = 0; i < re->nzones; ++i) {
709 if (re->zones[i]->device == dev) {
714 logical = re->logical;
716 atomic_inc(&dev->reada_in_flight);
717 ret = reada_tree_block_flagged(fs_info->extent_root, logical,
720 __readahead_hook(fs_info, re, NULL, logical, ret);
722 __readahead_hook(fs_info, re, eb, eb->start, ret);
725 free_extent_buffer(eb);
727 atomic_dec(&dev->reada_in_flight);
728 reada_extent_put(fs_info, re);
734 static void reada_start_machine_worker(struct btrfs_work *work)
736 struct reada_machine_work *rmw;
737 struct btrfs_fs_info *fs_info;
740 rmw = container_of(work, struct reada_machine_work, work);
741 fs_info = rmw->fs_info;
745 old_ioprio = IOPRIO_PRIO_VALUE(task_nice_ioclass(current),
746 task_nice_ioprio(current));
747 set_task_ioprio(current, BTRFS_IOPRIO_READA);
748 __reada_start_machine(fs_info);
749 set_task_ioprio(current, old_ioprio);
751 atomic_dec(&fs_info->reada_works_cnt);
754 static void __reada_start_machine(struct btrfs_fs_info *fs_info)
756 struct btrfs_device *device;
757 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
764 mutex_lock(&fs_devices->device_list_mutex);
765 list_for_each_entry(device, &fs_devices->devices, dev_list) {
766 if (atomic_read(&device->reada_in_flight) <
768 enqueued += reada_start_machine_dev(fs_info,
771 mutex_unlock(&fs_devices->device_list_mutex);
773 } while (enqueued && total < 10000);
779 * If everything is already in the cache, this is effectively single
780 * threaded. To a) not hold the caller for too long and b) to utilize
781 * more cores, we broke the loop above after 10000 iterations and now
782 * enqueue to workers to finish it. This will distribute the load to
785 for (i = 0; i < 2; ++i) {
786 reada_start_machine(fs_info);
787 if (atomic_read(&fs_info->reada_works_cnt) >
788 BTRFS_MAX_MIRRORS * 2)
793 static void reada_start_machine(struct btrfs_fs_info *fs_info)
795 struct reada_machine_work *rmw;
797 rmw = kzalloc(sizeof(*rmw), GFP_KERNEL);
799 /* FIXME we cannot handle this properly right now */
802 btrfs_init_work(&rmw->work, btrfs_readahead_helper,
803 reada_start_machine_worker, NULL, NULL);
804 rmw->fs_info = fs_info;
806 btrfs_queue_work(fs_info->readahead_workers, &rmw->work);
807 atomic_inc(&fs_info->reada_works_cnt);
811 static void dump_devs(struct btrfs_fs_info *fs_info, int all)
813 struct btrfs_device *device;
814 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
821 spin_lock(&fs_info->reada_lock);
822 list_for_each_entry(device, &fs_devices->devices, dev_list) {
823 printk(KERN_DEBUG "dev %lld has %d in flight\n", device->devid,
824 atomic_read(&device->reada_in_flight));
827 struct reada_zone *zone;
828 ret = radix_tree_gang_lookup(&device->reada_zones,
829 (void **)&zone, index, 1);
832 printk(KERN_DEBUG " zone %llu-%llu elems %llu locked "
833 "%d devs", zone->start, zone->end, zone->elems,
835 for (j = 0; j < zone->ndevs; ++j) {
836 printk(KERN_CONT " %lld",
837 zone->devs[j]->devid);
839 if (device->reada_curr_zone == zone)
840 printk(KERN_CONT " curr off %llu",
841 device->reada_next - zone->start);
842 printk(KERN_CONT "\n");
843 index = (zone->end >> PAGE_SHIFT) + 1;
848 struct reada_extent *re = NULL;
850 ret = radix_tree_gang_lookup(&device->reada_extents,
851 (void **)&re, index, 1);
855 " re: logical %llu size %u empty %d scheduled %d",
856 re->logical, fs_info->tree_root->nodesize,
857 list_empty(&re->extctl), re->scheduled);
859 for (i = 0; i < re->nzones; ++i) {
860 printk(KERN_CONT " zone %llu-%llu devs",
863 for (j = 0; j < re->zones[i]->ndevs; ++j) {
864 printk(KERN_CONT " %lld",
865 re->zones[i]->devs[j]->devid);
868 printk(KERN_CONT "\n");
869 index = (re->logical >> PAGE_SHIFT) + 1;
878 struct reada_extent *re = NULL;
880 ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re,
884 if (!re->scheduled) {
885 index = (re->logical >> PAGE_SHIFT) + 1;
889 "re: logical %llu size %u list empty %d scheduled %d",
890 re->logical, fs_info->tree_root->nodesize,
891 list_empty(&re->extctl), re->scheduled);
892 for (i = 0; i < re->nzones; ++i) {
893 printk(KERN_CONT " zone %llu-%llu devs",
896 for (j = 0; j < re->zones[i]->ndevs; ++j) {
897 printk(KERN_CONT " %lld",
898 re->zones[i]->devs[j]->devid);
901 printk(KERN_CONT "\n");
902 index = (re->logical >> PAGE_SHIFT) + 1;
904 spin_unlock(&fs_info->reada_lock);
911 struct reada_control *btrfs_reada_add(struct btrfs_root *root,
912 struct btrfs_key *key_start, struct btrfs_key *key_end)
914 struct reada_control *rc;
918 struct extent_buffer *node;
919 static struct btrfs_key max_key = {
925 rc = kzalloc(sizeof(*rc), GFP_KERNEL);
927 return ERR_PTR(-ENOMEM);
930 rc->key_start = *key_start;
931 rc->key_end = *key_end;
932 atomic_set(&rc->elems, 0);
933 init_waitqueue_head(&rc->wait);
934 kref_init(&rc->refcnt);
935 kref_get(&rc->refcnt); /* one ref for having elements */
937 node = btrfs_root_node(root);
939 generation = btrfs_header_generation(node);
940 free_extent_buffer(node);
942 ret = reada_add_block(rc, start, &max_key, generation);
948 reada_start_machine(root->fs_info);
954 int btrfs_reada_wait(void *handle)
956 struct reada_control *rc = handle;
957 struct btrfs_fs_info *fs_info = rc->root->fs_info;
959 while (atomic_read(&rc->elems)) {
960 if (!atomic_read(&fs_info->reada_works_cnt))
961 reada_start_machine(fs_info);
962 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
964 dump_devs(rc->root->fs_info,
965 atomic_read(&rc->elems) < 10 ? 1 : 0);
968 dump_devs(rc->root->fs_info, atomic_read(&rc->elems) < 10 ? 1 : 0);
970 kref_put(&rc->refcnt, reada_control_release);
975 int btrfs_reada_wait(void *handle)
977 struct reada_control *rc = handle;
978 struct btrfs_fs_info *fs_info = rc->root->fs_info;
980 while (atomic_read(&rc->elems)) {
981 if (!atomic_read(&fs_info->reada_works_cnt))
982 reada_start_machine(fs_info);
983 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
987 kref_put(&rc->refcnt, reada_control_release);
993 void btrfs_reada_detach(void *handle)
995 struct reada_control *rc = handle;
997 kref_put(&rc->refcnt, reada_control_release);