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"
34 * This is the implementation for the generic read ahead framework.
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).
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
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.
58 #define MAX_IN_FLIGHT 6
61 struct list_head list
;
62 struct reada_control
*rc
;
71 struct list_head extctl
;
74 struct reada_zone
*zones
[MAX_MIRRORS
];
76 struct btrfs_device
*scheduled_for
;
83 struct list_head list
;
86 struct btrfs_device
*device
;
87 struct btrfs_device
*devs
[MAX_MIRRORS
]; /* full list, incl self */
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
, int level
, u64 generation
);
107 /* in case of err, eb might be NULL */
108 static int __readahead_hook(struct btrfs_root
*root
, struct extent_buffer
*eb
,
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
;
123 level
= btrfs_header_level(eb
);
126 spin_lock(&fs_info
->reada_lock
);
127 re
= radix_tree_lookup(&fs_info
->reada_tree
, index
);
129 kref_get(&re
->refcnt
);
130 spin_unlock(&fs_info
->reada_lock
);
135 spin_lock(&re
->lock
);
137 * just take the full list from the extent. afterwards we
138 * don't need the lock anymore
140 list_replace_init(&re
->extctl
, &list
);
141 for_dev
= re
->scheduled_for
;
142 re
->scheduled_for
= NULL
;
143 spin_unlock(&re
->lock
);
146 nritems
= level
? btrfs_header_nritems(eb
) : 0;
147 generation
= btrfs_header_generation(eb
);
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.
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.
165 for (i
= 0; i
< nritems
; i
++) {
166 struct reada_extctl
*rec
;
168 struct btrfs_key key
;
169 struct btrfs_key next_key
;
171 btrfs_node_key_to_cpu(eb
, &key
, i
);
173 btrfs_node_key_to_cpu(eb
, &next_key
, i
+ 1);
176 bytenr
= btrfs_node_blockptr(eb
, i
);
177 n_gen
= btrfs_node_ptr_generation(eb
, i
);
179 list_for_each_entry(rec
, &list
, list
) {
180 struct reada_control
*rc
= rec
->rc
;
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
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
);
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
,
205 * free extctl records
207 while (!list_empty(&list
)) {
208 struct reada_control
*rc
;
209 struct reada_extctl
*rec
;
211 rec
= list_first_entry(&list
, struct reada_extctl
, list
);
212 list_del(&rec
->list
);
216 kref_get(&rc
->refcnt
);
217 if (atomic_dec_and_test(&rc
->elems
)) {
218 kref_put(&rc
->refcnt
, reada_control_release
);
221 kref_put(&rc
->refcnt
, reada_control_release
);
223 reada_extent_put(fs_info
, re
); /* one ref for each entry */
225 reada_extent_put(fs_info
, re
); /* our ref */
227 atomic_dec(&for_dev
->reada_in_flight
);
233 * start is passed separately in case eb in NULL, which may be the case with
236 int btree_readahead_hook(struct btrfs_root
*root
, struct extent_buffer
*eb
,
241 ret
= __readahead_hook(root
, eb
, start
, err
);
243 reada_start_machine(root
->fs_info
);
248 static 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
)
254 struct reada_zone
*zone
;
255 struct btrfs_block_group_cache
*cache
= 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);
266 kref_get(&zone
->refcnt
);
267 spin_unlock(&fs_info
->reada_lock
);
270 if (logical
>= zone
->start
&& logical
< zone
->end
)
272 spin_lock(&fs_info
->reada_lock
);
273 kref_put(&zone
->refcnt
, reada_zone_release
);
274 spin_unlock(&fs_info
->reada_lock
);
280 cache
= btrfs_lookup_block_group(fs_info
, logical
);
284 start
= cache
->key
.objectid
;
285 end
= start
+ cache
->key
.offset
- 1;
286 btrfs_put_block_group(cache
);
288 zone
= kzalloc(sizeof(*zone
), GFP_NOFS
);
294 INIT_LIST_HEAD(&zone
->list
);
295 spin_lock_init(&zone
->lock
);
297 kref_init(&zone
->refcnt
);
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
;
304 zone
->ndevs
= multi
->num_stripes
;
306 spin_lock(&fs_info
->reada_lock
);
307 ret
= radix_tree_insert(&dev
->reada_zones
,
308 (unsigned long)zone
->end
>> PAGE_CACHE_SHIFT
,
310 spin_unlock(&fs_info
->reada_lock
);
321 static struct reada_extent
*reada_find_extent(struct btrfs_root
*root
,
323 struct btrfs_key
*top
, int level
)
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
;
336 unsigned long index
= logical
>> PAGE_CACHE_SHIFT
;
339 spin_lock(&fs_info
->reada_lock
);
340 re
= radix_tree_lookup(&fs_info
->reada_tree
, index
);
342 kref_get(&re
->refcnt
);
343 spin_unlock(&fs_info
->reada_lock
);
348 re
= kzalloc(sizeof(*re
), GFP_NOFS
);
352 blocksize
= btrfs_level_size(root
, level
);
353 re
->logical
= logical
;
354 re
->blocksize
= blocksize
;
356 INIT_LIST_HEAD(&re
->extctl
);
357 spin_lock_init(&re
->lock
);
358 kref_init(&re
->refcnt
);
364 ret
= btrfs_map_block(map_tree
, REQ_WRITE
, logical
, &length
, &multi
, 0);
365 if (ret
|| !multi
|| length
< blocksize
)
368 if (multi
->num_stripes
> MAX_MIRRORS
) {
369 printk(KERN_ERR
"btrfs readahead: more than %d copies not "
370 "supported", MAX_MIRRORS
);
374 for (nzones
= 0; nzones
< multi
->num_stripes
; ++nzones
) {
375 struct reada_zone
*zone
;
377 dev
= multi
->stripes
[nzones
].dev
;
378 zone
= reada_find_zone(fs_info
, dev
, logical
, multi
);
382 re
->zones
[nzones
] = zone
;
383 spin_lock(&zone
->lock
);
385 kref_get(&zone
->refcnt
);
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
);
394 /* not a single zone found, error and out */
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
);
402 spin_unlock(&fs_info
->reada_lock
);
403 if (ret
!= -ENOMEM
) {
404 /* someone inserted the extent in the meantime */
409 for (i
= 0; i
< nzones
; ++i
) {
410 dev
= multi
->stripes
[i
].dev
;
411 ret
= radix_tree_insert(&dev
->reada_extents
, index
, re
);
414 dev
= multi
->stripes
[i
].dev
;
416 radix_tree_delete(&dev
->reada_extents
, index
);
418 BUG_ON(fs_info
== NULL
);
419 radix_tree_delete(&fs_info
->reada_tree
, index
);
420 spin_unlock(&fs_info
->reada_lock
);
424 spin_unlock(&fs_info
->reada_lock
);
430 struct reada_zone
*zone
;
433 zone
= re
->zones
[nzones
];
434 kref_get(&zone
->refcnt
);
435 spin_lock(&zone
->lock
);
437 if (zone
->elems
== 0) {
439 * no fs_info->reada_lock needed, as this can't be
442 kref_put(&zone
->refcnt
, reada_zone_release
);
444 spin_unlock(&zone
->lock
);
446 spin_lock(&fs_info
->reada_lock
);
447 kref_put(&zone
->refcnt
, reada_zone_release
);
448 spin_unlock(&fs_info
->reada_lock
);
456 static void reada_kref_dummy(struct kref
*kr
)
460 static void reada_extent_put(struct btrfs_fs_info
*fs_info
,
461 struct reada_extent
*re
)
464 unsigned long index
= re
->logical
>> PAGE_CACHE_SHIFT
;
466 spin_lock(&fs_info
->reada_lock
);
467 if (!kref_put(&re
->refcnt
, reada_kref_dummy
)) {
468 spin_unlock(&fs_info
->reada_lock
);
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
];
476 radix_tree_delete(&zone
->device
->reada_extents
, index
);
479 spin_unlock(&fs_info
->reada_lock
);
481 for (i
= 0; i
< re
->nzones
; ++i
) {
482 struct reada_zone
*zone
= re
->zones
[i
];
484 kref_get(&zone
->refcnt
);
485 spin_lock(&zone
->lock
);
487 if (zone
->elems
== 0) {
488 /* no fs_info->reada_lock needed, as this can't be
490 kref_put(&zone
->refcnt
, reada_zone_release
);
492 spin_unlock(&zone
->lock
);
494 spin_lock(&fs_info
->reada_lock
);
495 kref_put(&zone
->refcnt
, reada_zone_release
);
496 spin_unlock(&fs_info
->reada_lock
);
498 if (re
->scheduled_for
)
499 atomic_dec(&re
->scheduled_for
->reada_in_flight
);
504 static void reada_zone_release(struct kref
*kref
)
506 struct reada_zone
*zone
= container_of(kref
, struct reada_zone
, refcnt
);
508 radix_tree_delete(&zone
->device
->reada_zones
,
509 zone
->end
>> PAGE_CACHE_SHIFT
);
514 static void reada_control_release(struct kref
*kref
)
516 struct reada_control
*rc
= container_of(kref
, struct reada_control
,
522 static int reada_add_block(struct reada_control
*rc
, u64 logical
,
523 struct btrfs_key
*top
, int level
, u64 generation
)
525 struct btrfs_root
*root
= rc
->root
;
526 struct reada_extent
*re
;
527 struct reada_extctl
*rec
;
529 re
= reada_find_extent(root
, logical
, top
, level
); /* takes one ref */
533 rec
= kzalloc(sizeof(*rec
), GFP_NOFS
);
535 reada_extent_put(root
->fs_info
, re
);
540 rec
->generation
= generation
;
541 atomic_inc(&rc
->elems
);
543 spin_lock(&re
->lock
);
544 list_add_tail(&rec
->list
, &re
->extctl
);
545 spin_unlock(&re
->lock
);
547 /* leave the ref on the extent */
553 * called with fs_info->reada_lock held
555 static void reada_peer_zones_set_lock(struct reada_zone
*zone
, int lock
)
558 unsigned long index
= zone
->end
>> PAGE_CACHE_SHIFT
;
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
)
569 * called with fs_info->reada_lock held
571 static int reada_pick_zone(struct btrfs_device
*dev
)
573 struct reada_zone
*top_zone
= NULL
;
574 struct reada_zone
*top_locked_zone
= NULL
;
576 u64 top_locked_elems
= 0;
577 unsigned long index
= 0;
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
;
585 /* pick the zone with the most elements */
587 struct reada_zone
*zone
;
589 ret
= radix_tree_gang_lookup(&dev
->reada_zones
,
590 (void **)&zone
, index
, 1);
593 index
= (zone
->end
>> PAGE_CACHE_SHIFT
) + 1;
595 if (zone
->elems
> top_locked_elems
) {
596 top_locked_elems
= zone
->elems
;
597 top_locked_zone
= zone
;
600 if (zone
->elems
> top_elems
) {
601 top_elems
= zone
->elems
;
607 dev
->reada_curr_zone
= top_zone
;
608 else if (top_locked_zone
)
609 dev
->reada_curr_zone
= top_locked_zone
;
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);
620 static int reada_start_machine_dev(struct btrfs_fs_info
*fs_info
,
621 struct btrfs_device
*dev
)
623 struct reada_extent
*re
= NULL
;
625 struct extent_buffer
*eb
= NULL
;
632 spin_lock(&fs_info
->reada_lock
);
633 if (dev
->reada_curr_zone
== NULL
) {
634 ret
= reada_pick_zone(dev
);
636 spin_unlock(&fs_info
->reada_lock
);
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
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
);
650 spin_unlock(&fs_info
->reada_lock
);
654 ret
= radix_tree_gang_lookup(&dev
->reada_extents
, (void **)&re
,
655 dev
->reada_next
>> PAGE_CACHE_SHIFT
, 1);
658 spin_unlock(&fs_info
->reada_lock
);
661 dev
->reada_next
= re
->logical
+ re
->blocksize
;
662 kref_get(&re
->refcnt
);
664 spin_unlock(&fs_info
->reada_lock
);
669 for (i
= 0; i
< re
->nzones
; ++i
) {
670 if (re
->zones
[i
]->device
== dev
) {
675 logical
= re
->logical
;
676 blocksize
= re
->blocksize
;
678 spin_lock(&re
->lock
);
679 if (re
->scheduled_for
== NULL
) {
680 re
->scheduled_for
= dev
;
683 spin_unlock(&re
->lock
);
685 reada_extent_put(fs_info
, re
);
690 atomic_inc(&dev
->reada_in_flight
);
691 ret
= reada_tree_block_flagged(fs_info
->extent_root
, logical
, blocksize
,
694 __readahead_hook(fs_info
->extent_root
, NULL
, logical
, ret
);
696 __readahead_hook(fs_info
->extent_root
, eb
, eb
->start
, ret
);
699 free_extent_buffer(eb
);
705 static void reada_start_machine_worker(struct btrfs_work
*work
)
707 struct reada_machine_work
*rmw
;
708 struct btrfs_fs_info
*fs_info
;
710 rmw
= container_of(work
, struct reada_machine_work
, work
);
711 fs_info
= rmw
->fs_info
;
715 __reada_start_machine(fs_info
);
718 static void __reada_start_machine(struct btrfs_fs_info
*fs_info
)
720 struct btrfs_device
*device
;
721 struct btrfs_fs_devices
*fs_devices
= fs_info
->fs_devices
;
728 list_for_each_entry(device
, &fs_devices
->devices
, dev_list
) {
729 if (atomic_read(&device
->reada_in_flight
) <
731 enqueued
+= reada_start_machine_dev(fs_info
,
735 } while (enqueued
&& total
< 10000);
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
747 for (i
= 0; i
< 2; ++i
)
748 reada_start_machine(fs_info
);
751 static void reada_start_machine(struct btrfs_fs_info
*fs_info
)
753 struct reada_machine_work
*rmw
;
755 rmw
= kzalloc(sizeof(*rmw
), GFP_NOFS
);
757 /* FIXME we cannot handle this properly right now */
760 rmw
->work
.func
= reada_start_machine_worker
;
761 rmw
->fs_info
= fs_info
;
763 btrfs_queue_worker(&fs_info
->readahead_workers
, &rmw
->work
);
767 static void dump_devs(struct btrfs_fs_info
*fs_info
, int all
)
769 struct btrfs_device
*device
;
770 struct btrfs_fs_devices
*fs_devices
= fs_info
->fs_devices
;
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
));
783 struct reada_zone
*zone
;
784 ret
= radix_tree_gang_lookup(&device
->reada_zones
,
785 (void **)&zone
, index
, 1);
788 printk(KERN_DEBUG
" zone %llu-%llu elems %llu locked "
789 "%d devs", zone
->start
, zone
->end
, zone
->elems
,
791 for (j
= 0; j
< zone
->ndevs
; ++j
) {
792 printk(KERN_CONT
" %lld",
793 zone
->devs
[j
]->devid
);
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;
804 struct reada_extent
*re
= NULL
;
806 ret
= radix_tree_gang_lookup(&device
->reada_extents
,
807 (void **)&re
, index
, 1);
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);
816 for (i
= 0; i
< re
->nzones
; ++i
) {
817 printk(KERN_CONT
" zone %llu-%llu devs",
820 for (j
= 0; j
< re
->zones
[i
]->ndevs
; ++j
) {
821 printk(KERN_CONT
" %lld",
822 re
->zones
[i
]->devs
[j
]->devid
);
825 printk(KERN_CONT
"\n");
826 index
= (re
->logical
>> PAGE_CACHE_SHIFT
) + 1;
835 struct reada_extent
*re
= NULL
;
837 ret
= radix_tree_gang_lookup(&fs_info
->reada_tree
, (void **)&re
,
841 if (!re
->scheduled_for
) {
842 index
= (re
->logical
>> PAGE_CACHE_SHIFT
) + 1;
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",
853 for (i
= 0; i
< re
->nzones
; ++i
) {
854 printk(KERN_CONT
" zone %llu-%llu devs",
857 for (j
= 0; j
< re
->zones
[i
]->ndevs
; ++j
) {
858 printk(KERN_CONT
" %lld",
859 re
->zones
[i
]->devs
[j
]->devid
);
863 printk(KERN_CONT
"\n");
864 index
= (re
->logical
>> PAGE_CACHE_SHIFT
) + 1;
866 spin_unlock(&fs_info
->reada_lock
);
873 struct reada_control
*btrfs_reada_add(struct btrfs_root
*root
,
874 struct btrfs_key
*key_start
, struct btrfs_key
*key_end
)
876 struct reada_control
*rc
;
880 struct extent_buffer
*node
;
881 static struct btrfs_key max_key
= {
887 rc
= kzalloc(sizeof(*rc
), GFP_NOFS
);
889 return ERR_PTR(-ENOMEM
);
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 */
899 node
= btrfs_root_node(root
);
901 level
= btrfs_header_level(node
);
902 generation
= btrfs_header_generation(node
);
903 free_extent_buffer(node
);
905 reada_add_block(rc
, start
, &max_key
, level
, generation
);
907 reada_start_machine(root
->fs_info
);
913 int btrfs_reada_wait(void *handle
)
915 struct reada_control
*rc
= handle
;
917 while (atomic_read(&rc
->elems
)) {
918 wait_event_timeout(rc
->wait
, atomic_read(&rc
->elems
) == 0,
920 dump_devs(rc
->root
->fs_info
, rc
->elems
< 10 ? 1 : 0);
923 dump_devs(rc
->root
->fs_info
, rc
->elems
< 10 ? 1 : 0);
925 kref_put(&rc
->refcnt
, reada_control_release
);
930 int btrfs_reada_wait(void *handle
)
932 struct reada_control
*rc
= handle
;
934 while (atomic_read(&rc
->elems
)) {
935 wait_event(rc
->wait
, atomic_read(&rc
->elems
) == 0);
938 kref_put(&rc
->refcnt
, reada_control_release
);
944 void btrfs_reada_detach(void *handle
)
946 struct reada_control
*rc
= handle
;
948 kref_put(&rc
->refcnt
, reada_control_release
);