Btrfs: free space cache: make sure there is always room for generation number
[sfrench/cifs-2.6.git] / fs / btrfs / free-space-cache.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2008 Red Hat.  All rights reserved.
4  */
5
6 #include <linux/pagemap.h>
7 #include <linux/sched.h>
8 #include <linux/sched/signal.h>
9 #include <linux/slab.h>
10 #include <linux/math64.h>
11 #include <linux/ratelimit.h>
12 #include <linux/error-injection.h>
13 #include "ctree.h"
14 #include "free-space-cache.h"
15 #include "transaction.h"
16 #include "disk-io.h"
17 #include "extent_io.h"
18 #include "inode-map.h"
19 #include "volumes.h"
20
21 #define BITS_PER_BITMAP         (PAGE_SIZE * 8UL)
22 #define MAX_CACHE_BYTES_PER_GIG SZ_32K
23
24 struct btrfs_trim_range {
25         u64 start;
26         u64 bytes;
27         struct list_head list;
28 };
29
30 static int link_free_space(struct btrfs_free_space_ctl *ctl,
31                            struct btrfs_free_space *info);
32 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
33                               struct btrfs_free_space *info);
34 static int btrfs_wait_cache_io_root(struct btrfs_root *root,
35                              struct btrfs_trans_handle *trans,
36                              struct btrfs_io_ctl *io_ctl,
37                              struct btrfs_path *path);
38
39 static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
40                                                struct btrfs_path *path,
41                                                u64 offset)
42 {
43         struct btrfs_fs_info *fs_info = root->fs_info;
44         struct btrfs_key key;
45         struct btrfs_key location;
46         struct btrfs_disk_key disk_key;
47         struct btrfs_free_space_header *header;
48         struct extent_buffer *leaf;
49         struct inode *inode = NULL;
50         int ret;
51
52         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
53         key.offset = offset;
54         key.type = 0;
55
56         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
57         if (ret < 0)
58                 return ERR_PTR(ret);
59         if (ret > 0) {
60                 btrfs_release_path(path);
61                 return ERR_PTR(-ENOENT);
62         }
63
64         leaf = path->nodes[0];
65         header = btrfs_item_ptr(leaf, path->slots[0],
66                                 struct btrfs_free_space_header);
67         btrfs_free_space_key(leaf, header, &disk_key);
68         btrfs_disk_key_to_cpu(&location, &disk_key);
69         btrfs_release_path(path);
70
71         inode = btrfs_iget(fs_info->sb, &location, root, NULL);
72         if (IS_ERR(inode))
73                 return inode;
74         if (is_bad_inode(inode)) {
75                 iput(inode);
76                 return ERR_PTR(-ENOENT);
77         }
78
79         mapping_set_gfp_mask(inode->i_mapping,
80                         mapping_gfp_constraint(inode->i_mapping,
81                         ~(__GFP_FS | __GFP_HIGHMEM)));
82
83         return inode;
84 }
85
86 struct inode *lookup_free_space_inode(struct btrfs_fs_info *fs_info,
87                                       struct btrfs_block_group_cache
88                                       *block_group, struct btrfs_path *path)
89 {
90         struct inode *inode = NULL;
91         u32 flags = BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
92
93         spin_lock(&block_group->lock);
94         if (block_group->inode)
95                 inode = igrab(block_group->inode);
96         spin_unlock(&block_group->lock);
97         if (inode)
98                 return inode;
99
100         inode = __lookup_free_space_inode(fs_info->tree_root, path,
101                                           block_group->key.objectid);
102         if (IS_ERR(inode))
103                 return inode;
104
105         spin_lock(&block_group->lock);
106         if (!((BTRFS_I(inode)->flags & flags) == flags)) {
107                 btrfs_info(fs_info, "Old style space inode found, converting.");
108                 BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM |
109                         BTRFS_INODE_NODATACOW;
110                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
111         }
112
113         if (!block_group->iref) {
114                 block_group->inode = igrab(inode);
115                 block_group->iref = 1;
116         }
117         spin_unlock(&block_group->lock);
118
119         return inode;
120 }
121
122 static int __create_free_space_inode(struct btrfs_root *root,
123                                      struct btrfs_trans_handle *trans,
124                                      struct btrfs_path *path,
125                                      u64 ino, u64 offset)
126 {
127         struct btrfs_key key;
128         struct btrfs_disk_key disk_key;
129         struct btrfs_free_space_header *header;
130         struct btrfs_inode_item *inode_item;
131         struct extent_buffer *leaf;
132         u64 flags = BTRFS_INODE_NOCOMPRESS | BTRFS_INODE_PREALLOC;
133         int ret;
134
135         ret = btrfs_insert_empty_inode(trans, root, path, ino);
136         if (ret)
137                 return ret;
138
139         /* We inline crc's for the free disk space cache */
140         if (ino != BTRFS_FREE_INO_OBJECTID)
141                 flags |= BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
142
143         leaf = path->nodes[0];
144         inode_item = btrfs_item_ptr(leaf, path->slots[0],
145                                     struct btrfs_inode_item);
146         btrfs_item_key(leaf, &disk_key, path->slots[0]);
147         memzero_extent_buffer(leaf, (unsigned long)inode_item,
148                              sizeof(*inode_item));
149         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
150         btrfs_set_inode_size(leaf, inode_item, 0);
151         btrfs_set_inode_nbytes(leaf, inode_item, 0);
152         btrfs_set_inode_uid(leaf, inode_item, 0);
153         btrfs_set_inode_gid(leaf, inode_item, 0);
154         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
155         btrfs_set_inode_flags(leaf, inode_item, flags);
156         btrfs_set_inode_nlink(leaf, inode_item, 1);
157         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
158         btrfs_set_inode_block_group(leaf, inode_item, offset);
159         btrfs_mark_buffer_dirty(leaf);
160         btrfs_release_path(path);
161
162         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
163         key.offset = offset;
164         key.type = 0;
165         ret = btrfs_insert_empty_item(trans, root, path, &key,
166                                       sizeof(struct btrfs_free_space_header));
167         if (ret < 0) {
168                 btrfs_release_path(path);
169                 return ret;
170         }
171
172         leaf = path->nodes[0];
173         header = btrfs_item_ptr(leaf, path->slots[0],
174                                 struct btrfs_free_space_header);
175         memzero_extent_buffer(leaf, (unsigned long)header, sizeof(*header));
176         btrfs_set_free_space_key(leaf, header, &disk_key);
177         btrfs_mark_buffer_dirty(leaf);
178         btrfs_release_path(path);
179
180         return 0;
181 }
182
183 int create_free_space_inode(struct btrfs_fs_info *fs_info,
184                             struct btrfs_trans_handle *trans,
185                             struct btrfs_block_group_cache *block_group,
186                             struct btrfs_path *path)
187 {
188         int ret;
189         u64 ino;
190
191         ret = btrfs_find_free_objectid(fs_info->tree_root, &ino);
192         if (ret < 0)
193                 return ret;
194
195         return __create_free_space_inode(fs_info->tree_root, trans, path, ino,
196                                          block_group->key.objectid);
197 }
198
199 int btrfs_check_trunc_cache_free_space(struct btrfs_fs_info *fs_info,
200                                        struct btrfs_block_rsv *rsv)
201 {
202         u64 needed_bytes;
203         int ret;
204
205         /* 1 for slack space, 1 for updating the inode */
206         needed_bytes = btrfs_calc_trunc_metadata_size(fs_info, 1) +
207                 btrfs_calc_trans_metadata_size(fs_info, 1);
208
209         spin_lock(&rsv->lock);
210         if (rsv->reserved < needed_bytes)
211                 ret = -ENOSPC;
212         else
213                 ret = 0;
214         spin_unlock(&rsv->lock);
215         return ret;
216 }
217
218 int btrfs_truncate_free_space_cache(struct btrfs_trans_handle *trans,
219                                     struct btrfs_block_group_cache *block_group,
220                                     struct inode *inode)
221 {
222         struct btrfs_root *root = BTRFS_I(inode)->root;
223         int ret = 0;
224         bool locked = false;
225
226         if (block_group) {
227                 struct btrfs_path *path = btrfs_alloc_path();
228
229                 if (!path) {
230                         ret = -ENOMEM;
231                         goto fail;
232                 }
233                 locked = true;
234                 mutex_lock(&trans->transaction->cache_write_mutex);
235                 if (!list_empty(&block_group->io_list)) {
236                         list_del_init(&block_group->io_list);
237
238                         btrfs_wait_cache_io(trans, block_group, path);
239                         btrfs_put_block_group(block_group);
240                 }
241
242                 /*
243                  * now that we've truncated the cache away, its no longer
244                  * setup or written
245                  */
246                 spin_lock(&block_group->lock);
247                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
248                 spin_unlock(&block_group->lock);
249                 btrfs_free_path(path);
250         }
251
252         btrfs_i_size_write(BTRFS_I(inode), 0);
253         truncate_pagecache(inode, 0);
254
255         /*
256          * We skip the throttling logic for free space cache inodes, so we don't
257          * need to check for -EAGAIN.
258          */
259         ret = btrfs_truncate_inode_items(trans, root, inode,
260                                          0, BTRFS_EXTENT_DATA_KEY);
261         if (ret)
262                 goto fail;
263
264         ret = btrfs_update_inode(trans, root, inode);
265
266 fail:
267         if (locked)
268                 mutex_unlock(&trans->transaction->cache_write_mutex);
269         if (ret)
270                 btrfs_abort_transaction(trans, ret);
271
272         return ret;
273 }
274
275 static void readahead_cache(struct inode *inode)
276 {
277         struct file_ra_state *ra;
278         unsigned long last_index;
279
280         ra = kzalloc(sizeof(*ra), GFP_NOFS);
281         if (!ra)
282                 return;
283
284         file_ra_state_init(ra, inode->i_mapping);
285         last_index = (i_size_read(inode) - 1) >> PAGE_SHIFT;
286
287         page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
288
289         kfree(ra);
290 }
291
292 static int io_ctl_init(struct btrfs_io_ctl *io_ctl, struct inode *inode,
293                        int write)
294 {
295         int num_pages;
296         int check_crcs = 0;
297
298         num_pages = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
299
300         if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FREE_INO_OBJECTID)
301                 check_crcs = 1;
302
303         /* Make sure we can fit our crcs and generation into the first page */
304         if (write && check_crcs &&
305             (num_pages * sizeof(u32) + sizeof(u64)) > PAGE_SIZE)
306                 return -ENOSPC;
307
308         memset(io_ctl, 0, sizeof(struct btrfs_io_ctl));
309
310         io_ctl->pages = kcalloc(num_pages, sizeof(struct page *), GFP_NOFS);
311         if (!io_ctl->pages)
312                 return -ENOMEM;
313
314         io_ctl->num_pages = num_pages;
315         io_ctl->fs_info = btrfs_sb(inode->i_sb);
316         io_ctl->check_crcs = check_crcs;
317         io_ctl->inode = inode;
318
319         return 0;
320 }
321 ALLOW_ERROR_INJECTION(io_ctl_init, ERRNO);
322
323 static void io_ctl_free(struct btrfs_io_ctl *io_ctl)
324 {
325         kfree(io_ctl->pages);
326         io_ctl->pages = NULL;
327 }
328
329 static void io_ctl_unmap_page(struct btrfs_io_ctl *io_ctl)
330 {
331         if (io_ctl->cur) {
332                 io_ctl->cur = NULL;
333                 io_ctl->orig = NULL;
334         }
335 }
336
337 static void io_ctl_map_page(struct btrfs_io_ctl *io_ctl, int clear)
338 {
339         ASSERT(io_ctl->index < io_ctl->num_pages);
340         io_ctl->page = io_ctl->pages[io_ctl->index++];
341         io_ctl->cur = page_address(io_ctl->page);
342         io_ctl->orig = io_ctl->cur;
343         io_ctl->size = PAGE_SIZE;
344         if (clear)
345                 clear_page(io_ctl->cur);
346 }
347
348 static void io_ctl_drop_pages(struct btrfs_io_ctl *io_ctl)
349 {
350         int i;
351
352         io_ctl_unmap_page(io_ctl);
353
354         for (i = 0; i < io_ctl->num_pages; i++) {
355                 if (io_ctl->pages[i]) {
356                         ClearPageChecked(io_ctl->pages[i]);
357                         unlock_page(io_ctl->pages[i]);
358                         put_page(io_ctl->pages[i]);
359                 }
360         }
361 }
362
363 static int io_ctl_prepare_pages(struct btrfs_io_ctl *io_ctl, struct inode *inode,
364                                 int uptodate)
365 {
366         struct page *page;
367         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
368         int i;
369
370         for (i = 0; i < io_ctl->num_pages; i++) {
371                 page = find_or_create_page(inode->i_mapping, i, mask);
372                 if (!page) {
373                         io_ctl_drop_pages(io_ctl);
374                         return -ENOMEM;
375                 }
376                 io_ctl->pages[i] = page;
377                 if (uptodate && !PageUptodate(page)) {
378                         btrfs_readpage(NULL, page);
379                         lock_page(page);
380                         if (!PageUptodate(page)) {
381                                 btrfs_err(BTRFS_I(inode)->root->fs_info,
382                                            "error reading free space cache");
383                                 io_ctl_drop_pages(io_ctl);
384                                 return -EIO;
385                         }
386                 }
387         }
388
389         for (i = 0; i < io_ctl->num_pages; i++) {
390                 clear_page_dirty_for_io(io_ctl->pages[i]);
391                 set_page_extent_mapped(io_ctl->pages[i]);
392         }
393
394         return 0;
395 }
396
397 static void io_ctl_set_generation(struct btrfs_io_ctl *io_ctl, u64 generation)
398 {
399         __le64 *val;
400
401         io_ctl_map_page(io_ctl, 1);
402
403         /*
404          * Skip the csum areas.  If we don't check crcs then we just have a
405          * 64bit chunk at the front of the first page.
406          */
407         if (io_ctl->check_crcs) {
408                 io_ctl->cur += (sizeof(u32) * io_ctl->num_pages);
409                 io_ctl->size -= sizeof(u64) + (sizeof(u32) * io_ctl->num_pages);
410         } else {
411                 io_ctl->cur += sizeof(u64);
412                 io_ctl->size -= sizeof(u64) * 2;
413         }
414
415         val = io_ctl->cur;
416         *val = cpu_to_le64(generation);
417         io_ctl->cur += sizeof(u64);
418 }
419
420 static int io_ctl_check_generation(struct btrfs_io_ctl *io_ctl, u64 generation)
421 {
422         __le64 *gen;
423
424         /*
425          * Skip the crc area.  If we don't check crcs then we just have a 64bit
426          * chunk at the front of the first page.
427          */
428         if (io_ctl->check_crcs) {
429                 io_ctl->cur += sizeof(u32) * io_ctl->num_pages;
430                 io_ctl->size -= sizeof(u64) +
431                         (sizeof(u32) * io_ctl->num_pages);
432         } else {
433                 io_ctl->cur += sizeof(u64);
434                 io_ctl->size -= sizeof(u64) * 2;
435         }
436
437         gen = io_ctl->cur;
438         if (le64_to_cpu(*gen) != generation) {
439                 btrfs_err_rl(io_ctl->fs_info,
440                         "space cache generation (%llu) does not match inode (%llu)",
441                                 *gen, generation);
442                 io_ctl_unmap_page(io_ctl);
443                 return -EIO;
444         }
445         io_ctl->cur += sizeof(u64);
446         return 0;
447 }
448
449 static void io_ctl_set_crc(struct btrfs_io_ctl *io_ctl, int index)
450 {
451         u32 *tmp;
452         u32 crc = ~(u32)0;
453         unsigned offset = 0;
454
455         if (!io_ctl->check_crcs) {
456                 io_ctl_unmap_page(io_ctl);
457                 return;
458         }
459
460         if (index == 0)
461                 offset = sizeof(u32) * io_ctl->num_pages;
462
463         crc = btrfs_csum_data(io_ctl->orig + offset, crc,
464                               PAGE_SIZE - offset);
465         btrfs_csum_final(crc, (u8 *)&crc);
466         io_ctl_unmap_page(io_ctl);
467         tmp = page_address(io_ctl->pages[0]);
468         tmp += index;
469         *tmp = crc;
470 }
471
472 static int io_ctl_check_crc(struct btrfs_io_ctl *io_ctl, int index)
473 {
474         u32 *tmp, val;
475         u32 crc = ~(u32)0;
476         unsigned offset = 0;
477
478         if (!io_ctl->check_crcs) {
479                 io_ctl_map_page(io_ctl, 0);
480                 return 0;
481         }
482
483         if (index == 0)
484                 offset = sizeof(u32) * io_ctl->num_pages;
485
486         tmp = page_address(io_ctl->pages[0]);
487         tmp += index;
488         val = *tmp;
489
490         io_ctl_map_page(io_ctl, 0);
491         crc = btrfs_csum_data(io_ctl->orig + offset, crc,
492                               PAGE_SIZE - offset);
493         btrfs_csum_final(crc, (u8 *)&crc);
494         if (val != crc) {
495                 btrfs_err_rl(io_ctl->fs_info,
496                         "csum mismatch on free space cache");
497                 io_ctl_unmap_page(io_ctl);
498                 return -EIO;
499         }
500
501         return 0;
502 }
503
504 static int io_ctl_add_entry(struct btrfs_io_ctl *io_ctl, u64 offset, u64 bytes,
505                             void *bitmap)
506 {
507         struct btrfs_free_space_entry *entry;
508
509         if (!io_ctl->cur)
510                 return -ENOSPC;
511
512         entry = io_ctl->cur;
513         entry->offset = cpu_to_le64(offset);
514         entry->bytes = cpu_to_le64(bytes);
515         entry->type = (bitmap) ? BTRFS_FREE_SPACE_BITMAP :
516                 BTRFS_FREE_SPACE_EXTENT;
517         io_ctl->cur += sizeof(struct btrfs_free_space_entry);
518         io_ctl->size -= sizeof(struct btrfs_free_space_entry);
519
520         if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
521                 return 0;
522
523         io_ctl_set_crc(io_ctl, io_ctl->index - 1);
524
525         /* No more pages to map */
526         if (io_ctl->index >= io_ctl->num_pages)
527                 return 0;
528
529         /* map the next page */
530         io_ctl_map_page(io_ctl, 1);
531         return 0;
532 }
533
534 static int io_ctl_add_bitmap(struct btrfs_io_ctl *io_ctl, void *bitmap)
535 {
536         if (!io_ctl->cur)
537                 return -ENOSPC;
538
539         /*
540          * If we aren't at the start of the current page, unmap this one and
541          * map the next one if there is any left.
542          */
543         if (io_ctl->cur != io_ctl->orig) {
544                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
545                 if (io_ctl->index >= io_ctl->num_pages)
546                         return -ENOSPC;
547                 io_ctl_map_page(io_ctl, 0);
548         }
549
550         memcpy(io_ctl->cur, bitmap, PAGE_SIZE);
551         io_ctl_set_crc(io_ctl, io_ctl->index - 1);
552         if (io_ctl->index < io_ctl->num_pages)
553                 io_ctl_map_page(io_ctl, 0);
554         return 0;
555 }
556
557 static void io_ctl_zero_remaining_pages(struct btrfs_io_ctl *io_ctl)
558 {
559         /*
560          * If we're not on the boundary we know we've modified the page and we
561          * need to crc the page.
562          */
563         if (io_ctl->cur != io_ctl->orig)
564                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
565         else
566                 io_ctl_unmap_page(io_ctl);
567
568         while (io_ctl->index < io_ctl->num_pages) {
569                 io_ctl_map_page(io_ctl, 1);
570                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
571         }
572 }
573
574 static int io_ctl_read_entry(struct btrfs_io_ctl *io_ctl,
575                             struct btrfs_free_space *entry, u8 *type)
576 {
577         struct btrfs_free_space_entry *e;
578         int ret;
579
580         if (!io_ctl->cur) {
581                 ret = io_ctl_check_crc(io_ctl, io_ctl->index);
582                 if (ret)
583                         return ret;
584         }
585
586         e = io_ctl->cur;
587         entry->offset = le64_to_cpu(e->offset);
588         entry->bytes = le64_to_cpu(e->bytes);
589         *type = e->type;
590         io_ctl->cur += sizeof(struct btrfs_free_space_entry);
591         io_ctl->size -= sizeof(struct btrfs_free_space_entry);
592
593         if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
594                 return 0;
595
596         io_ctl_unmap_page(io_ctl);
597
598         return 0;
599 }
600
601 static int io_ctl_read_bitmap(struct btrfs_io_ctl *io_ctl,
602                               struct btrfs_free_space *entry)
603 {
604         int ret;
605
606         ret = io_ctl_check_crc(io_ctl, io_ctl->index);
607         if (ret)
608                 return ret;
609
610         memcpy(entry->bitmap, io_ctl->cur, PAGE_SIZE);
611         io_ctl_unmap_page(io_ctl);
612
613         return 0;
614 }
615
616 /*
617  * Since we attach pinned extents after the fact we can have contiguous sections
618  * of free space that are split up in entries.  This poses a problem with the
619  * tree logging stuff since it could have allocated across what appears to be 2
620  * entries since we would have merged the entries when adding the pinned extents
621  * back to the free space cache.  So run through the space cache that we just
622  * loaded and merge contiguous entries.  This will make the log replay stuff not
623  * blow up and it will make for nicer allocator behavior.
624  */
625 static void merge_space_tree(struct btrfs_free_space_ctl *ctl)
626 {
627         struct btrfs_free_space *e, *prev = NULL;
628         struct rb_node *n;
629
630 again:
631         spin_lock(&ctl->tree_lock);
632         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
633                 e = rb_entry(n, struct btrfs_free_space, offset_index);
634                 if (!prev)
635                         goto next;
636                 if (e->bitmap || prev->bitmap)
637                         goto next;
638                 if (prev->offset + prev->bytes == e->offset) {
639                         unlink_free_space(ctl, prev);
640                         unlink_free_space(ctl, e);
641                         prev->bytes += e->bytes;
642                         kmem_cache_free(btrfs_free_space_cachep, e);
643                         link_free_space(ctl, prev);
644                         prev = NULL;
645                         spin_unlock(&ctl->tree_lock);
646                         goto again;
647                 }
648 next:
649                 prev = e;
650         }
651         spin_unlock(&ctl->tree_lock);
652 }
653
654 static int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
655                                    struct btrfs_free_space_ctl *ctl,
656                                    struct btrfs_path *path, u64 offset)
657 {
658         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
659         struct btrfs_free_space_header *header;
660         struct extent_buffer *leaf;
661         struct btrfs_io_ctl io_ctl;
662         struct btrfs_key key;
663         struct btrfs_free_space *e, *n;
664         LIST_HEAD(bitmaps);
665         u64 num_entries;
666         u64 num_bitmaps;
667         u64 generation;
668         u8 type;
669         int ret = 0;
670
671         /* Nothing in the space cache, goodbye */
672         if (!i_size_read(inode))
673                 return 0;
674
675         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
676         key.offset = offset;
677         key.type = 0;
678
679         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
680         if (ret < 0)
681                 return 0;
682         else if (ret > 0) {
683                 btrfs_release_path(path);
684                 return 0;
685         }
686
687         ret = -1;
688
689         leaf = path->nodes[0];
690         header = btrfs_item_ptr(leaf, path->slots[0],
691                                 struct btrfs_free_space_header);
692         num_entries = btrfs_free_space_entries(leaf, header);
693         num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
694         generation = btrfs_free_space_generation(leaf, header);
695         btrfs_release_path(path);
696
697         if (!BTRFS_I(inode)->generation) {
698                 btrfs_info(fs_info,
699                            "the free space cache file (%llu) is invalid, skip it",
700                            offset);
701                 return 0;
702         }
703
704         if (BTRFS_I(inode)->generation != generation) {
705                 btrfs_err(fs_info,
706                           "free space inode generation (%llu) did not match free space cache generation (%llu)",
707                           BTRFS_I(inode)->generation, generation);
708                 return 0;
709         }
710
711         if (!num_entries)
712                 return 0;
713
714         ret = io_ctl_init(&io_ctl, inode, 0);
715         if (ret)
716                 return ret;
717
718         readahead_cache(inode);
719
720         ret = io_ctl_prepare_pages(&io_ctl, inode, 1);
721         if (ret)
722                 goto out;
723
724         ret = io_ctl_check_crc(&io_ctl, 0);
725         if (ret)
726                 goto free_cache;
727
728         ret = io_ctl_check_generation(&io_ctl, generation);
729         if (ret)
730                 goto free_cache;
731
732         while (num_entries) {
733                 e = kmem_cache_zalloc(btrfs_free_space_cachep,
734                                       GFP_NOFS);
735                 if (!e)
736                         goto free_cache;
737
738                 ret = io_ctl_read_entry(&io_ctl, e, &type);
739                 if (ret) {
740                         kmem_cache_free(btrfs_free_space_cachep, e);
741                         goto free_cache;
742                 }
743
744                 if (!e->bytes) {
745                         kmem_cache_free(btrfs_free_space_cachep, e);
746                         goto free_cache;
747                 }
748
749                 if (type == BTRFS_FREE_SPACE_EXTENT) {
750                         spin_lock(&ctl->tree_lock);
751                         ret = link_free_space(ctl, e);
752                         spin_unlock(&ctl->tree_lock);
753                         if (ret) {
754                                 btrfs_err(fs_info,
755                                         "Duplicate entries in free space cache, dumping");
756                                 kmem_cache_free(btrfs_free_space_cachep, e);
757                                 goto free_cache;
758                         }
759                 } else {
760                         ASSERT(num_bitmaps);
761                         num_bitmaps--;
762                         e->bitmap = kzalloc(PAGE_SIZE, GFP_NOFS);
763                         if (!e->bitmap) {
764                                 kmem_cache_free(
765                                         btrfs_free_space_cachep, e);
766                                 goto free_cache;
767                         }
768                         spin_lock(&ctl->tree_lock);
769                         ret = link_free_space(ctl, e);
770                         ctl->total_bitmaps++;
771                         ctl->op->recalc_thresholds(ctl);
772                         spin_unlock(&ctl->tree_lock);
773                         if (ret) {
774                                 btrfs_err(fs_info,
775                                         "Duplicate entries in free space cache, dumping");
776                                 kmem_cache_free(btrfs_free_space_cachep, e);
777                                 goto free_cache;
778                         }
779                         list_add_tail(&e->list, &bitmaps);
780                 }
781
782                 num_entries--;
783         }
784
785         io_ctl_unmap_page(&io_ctl);
786
787         /*
788          * We add the bitmaps at the end of the entries in order that
789          * the bitmap entries are added to the cache.
790          */
791         list_for_each_entry_safe(e, n, &bitmaps, list) {
792                 list_del_init(&e->list);
793                 ret = io_ctl_read_bitmap(&io_ctl, e);
794                 if (ret)
795                         goto free_cache;
796         }
797
798         io_ctl_drop_pages(&io_ctl);
799         merge_space_tree(ctl);
800         ret = 1;
801 out:
802         io_ctl_free(&io_ctl);
803         return ret;
804 free_cache:
805         io_ctl_drop_pages(&io_ctl);
806         __btrfs_remove_free_space_cache(ctl);
807         goto out;
808 }
809
810 int load_free_space_cache(struct btrfs_fs_info *fs_info,
811                           struct btrfs_block_group_cache *block_group)
812 {
813         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
814         struct inode *inode;
815         struct btrfs_path *path;
816         int ret = 0;
817         bool matched;
818         u64 used = btrfs_block_group_used(&block_group->item);
819
820         /*
821          * If this block group has been marked to be cleared for one reason or
822          * another then we can't trust the on disk cache, so just return.
823          */
824         spin_lock(&block_group->lock);
825         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
826                 spin_unlock(&block_group->lock);
827                 return 0;
828         }
829         spin_unlock(&block_group->lock);
830
831         path = btrfs_alloc_path();
832         if (!path)
833                 return 0;
834         path->search_commit_root = 1;
835         path->skip_locking = 1;
836
837         inode = lookup_free_space_inode(fs_info, block_group, path);
838         if (IS_ERR(inode)) {
839                 btrfs_free_path(path);
840                 return 0;
841         }
842
843         /* We may have converted the inode and made the cache invalid. */
844         spin_lock(&block_group->lock);
845         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
846                 spin_unlock(&block_group->lock);
847                 btrfs_free_path(path);
848                 goto out;
849         }
850         spin_unlock(&block_group->lock);
851
852         ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
853                                       path, block_group->key.objectid);
854         btrfs_free_path(path);
855         if (ret <= 0)
856                 goto out;
857
858         spin_lock(&ctl->tree_lock);
859         matched = (ctl->free_space == (block_group->key.offset - used -
860                                        block_group->bytes_super));
861         spin_unlock(&ctl->tree_lock);
862
863         if (!matched) {
864                 __btrfs_remove_free_space_cache(ctl);
865                 btrfs_warn(fs_info,
866                            "block group %llu has wrong amount of free space",
867                            block_group->key.objectid);
868                 ret = -1;
869         }
870 out:
871         if (ret < 0) {
872                 /* This cache is bogus, make sure it gets cleared */
873                 spin_lock(&block_group->lock);
874                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
875                 spin_unlock(&block_group->lock);
876                 ret = 0;
877
878                 btrfs_warn(fs_info,
879                            "failed to load free space cache for block group %llu, rebuilding it now",
880                            block_group->key.objectid);
881         }
882
883         iput(inode);
884         return ret;
885 }
886
887 static noinline_for_stack
888 int write_cache_extent_entries(struct btrfs_io_ctl *io_ctl,
889                               struct btrfs_free_space_ctl *ctl,
890                               struct btrfs_block_group_cache *block_group,
891                               int *entries, int *bitmaps,
892                               struct list_head *bitmap_list)
893 {
894         int ret;
895         struct btrfs_free_cluster *cluster = NULL;
896         struct btrfs_free_cluster *cluster_locked = NULL;
897         struct rb_node *node = rb_first(&ctl->free_space_offset);
898         struct btrfs_trim_range *trim_entry;
899
900         /* Get the cluster for this block_group if it exists */
901         if (block_group && !list_empty(&block_group->cluster_list)) {
902                 cluster = list_entry(block_group->cluster_list.next,
903                                      struct btrfs_free_cluster,
904                                      block_group_list);
905         }
906
907         if (!node && cluster) {
908                 cluster_locked = cluster;
909                 spin_lock(&cluster_locked->lock);
910                 node = rb_first(&cluster->root);
911                 cluster = NULL;
912         }
913
914         /* Write out the extent entries */
915         while (node) {
916                 struct btrfs_free_space *e;
917
918                 e = rb_entry(node, struct btrfs_free_space, offset_index);
919                 *entries += 1;
920
921                 ret = io_ctl_add_entry(io_ctl, e->offset, e->bytes,
922                                        e->bitmap);
923                 if (ret)
924                         goto fail;
925
926                 if (e->bitmap) {
927                         list_add_tail(&e->list, bitmap_list);
928                         *bitmaps += 1;
929                 }
930                 node = rb_next(node);
931                 if (!node && cluster) {
932                         node = rb_first(&cluster->root);
933                         cluster_locked = cluster;
934                         spin_lock(&cluster_locked->lock);
935                         cluster = NULL;
936                 }
937         }
938         if (cluster_locked) {
939                 spin_unlock(&cluster_locked->lock);
940                 cluster_locked = NULL;
941         }
942
943         /*
944          * Make sure we don't miss any range that was removed from our rbtree
945          * because trimming is running. Otherwise after a umount+mount (or crash
946          * after committing the transaction) we would leak free space and get
947          * an inconsistent free space cache report from fsck.
948          */
949         list_for_each_entry(trim_entry, &ctl->trimming_ranges, list) {
950                 ret = io_ctl_add_entry(io_ctl, trim_entry->start,
951                                        trim_entry->bytes, NULL);
952                 if (ret)
953                         goto fail;
954                 *entries += 1;
955         }
956
957         return 0;
958 fail:
959         if (cluster_locked)
960                 spin_unlock(&cluster_locked->lock);
961         return -ENOSPC;
962 }
963
964 static noinline_for_stack int
965 update_cache_item(struct btrfs_trans_handle *trans,
966                   struct btrfs_root *root,
967                   struct inode *inode,
968                   struct btrfs_path *path, u64 offset,
969                   int entries, int bitmaps)
970 {
971         struct btrfs_key key;
972         struct btrfs_free_space_header *header;
973         struct extent_buffer *leaf;
974         int ret;
975
976         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
977         key.offset = offset;
978         key.type = 0;
979
980         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
981         if (ret < 0) {
982                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
983                                  EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL);
984                 goto fail;
985         }
986         leaf = path->nodes[0];
987         if (ret > 0) {
988                 struct btrfs_key found_key;
989                 ASSERT(path->slots[0]);
990                 path->slots[0]--;
991                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
992                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
993                     found_key.offset != offset) {
994                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0,
995                                          inode->i_size - 1,
996                                          EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0,
997                                          NULL);
998                         btrfs_release_path(path);
999                         goto fail;
1000                 }
1001         }
1002
1003         BTRFS_I(inode)->generation = trans->transid;
1004         header = btrfs_item_ptr(leaf, path->slots[0],
1005                                 struct btrfs_free_space_header);
1006         btrfs_set_free_space_entries(leaf, header, entries);
1007         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
1008         btrfs_set_free_space_generation(leaf, header, trans->transid);
1009         btrfs_mark_buffer_dirty(leaf);
1010         btrfs_release_path(path);
1011
1012         return 0;
1013
1014 fail:
1015         return -1;
1016 }
1017
1018 static noinline_for_stack int
1019 write_pinned_extent_entries(struct btrfs_fs_info *fs_info,
1020                             struct btrfs_block_group_cache *block_group,
1021                             struct btrfs_io_ctl *io_ctl,
1022                             int *entries)
1023 {
1024         u64 start, extent_start, extent_end, len;
1025         struct extent_io_tree *unpin = NULL;
1026         int ret;
1027
1028         if (!block_group)
1029                 return 0;
1030
1031         /*
1032          * We want to add any pinned extents to our free space cache
1033          * so we don't leak the space
1034          *
1035          * We shouldn't have switched the pinned extents yet so this is the
1036          * right one
1037          */
1038         unpin = fs_info->pinned_extents;
1039
1040         start = block_group->key.objectid;
1041
1042         while (start < block_group->key.objectid + block_group->key.offset) {
1043                 ret = find_first_extent_bit(unpin, start,
1044                                             &extent_start, &extent_end,
1045                                             EXTENT_DIRTY, NULL);
1046                 if (ret)
1047                         return 0;
1048
1049                 /* This pinned extent is out of our range */
1050                 if (extent_start >= block_group->key.objectid +
1051                     block_group->key.offset)
1052                         return 0;
1053
1054                 extent_start = max(extent_start, start);
1055                 extent_end = min(block_group->key.objectid +
1056                                  block_group->key.offset, extent_end + 1);
1057                 len = extent_end - extent_start;
1058
1059                 *entries += 1;
1060                 ret = io_ctl_add_entry(io_ctl, extent_start, len, NULL);
1061                 if (ret)
1062                         return -ENOSPC;
1063
1064                 start = extent_end;
1065         }
1066
1067         return 0;
1068 }
1069
1070 static noinline_for_stack int
1071 write_bitmap_entries(struct btrfs_io_ctl *io_ctl, struct list_head *bitmap_list)
1072 {
1073         struct btrfs_free_space *entry, *next;
1074         int ret;
1075
1076         /* Write out the bitmaps */
1077         list_for_each_entry_safe(entry, next, bitmap_list, list) {
1078                 ret = io_ctl_add_bitmap(io_ctl, entry->bitmap);
1079                 if (ret)
1080                         return -ENOSPC;
1081                 list_del_init(&entry->list);
1082         }
1083
1084         return 0;
1085 }
1086
1087 static int flush_dirty_cache(struct inode *inode)
1088 {
1089         int ret;
1090
1091         ret = btrfs_wait_ordered_range(inode, 0, (u64)-1);
1092         if (ret)
1093                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
1094                                  EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL);
1095
1096         return ret;
1097 }
1098
1099 static void noinline_for_stack
1100 cleanup_bitmap_list(struct list_head *bitmap_list)
1101 {
1102         struct btrfs_free_space *entry, *next;
1103
1104         list_for_each_entry_safe(entry, next, bitmap_list, list)
1105                 list_del_init(&entry->list);
1106 }
1107
1108 static void noinline_for_stack
1109 cleanup_write_cache_enospc(struct inode *inode,
1110                            struct btrfs_io_ctl *io_ctl,
1111                            struct extent_state **cached_state)
1112 {
1113         io_ctl_drop_pages(io_ctl);
1114         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
1115                              i_size_read(inode) - 1, cached_state);
1116 }
1117
1118 static int __btrfs_wait_cache_io(struct btrfs_root *root,
1119                                  struct btrfs_trans_handle *trans,
1120                                  struct btrfs_block_group_cache *block_group,
1121                                  struct btrfs_io_ctl *io_ctl,
1122                                  struct btrfs_path *path, u64 offset)
1123 {
1124         int ret;
1125         struct inode *inode = io_ctl->inode;
1126         struct btrfs_fs_info *fs_info;
1127
1128         if (!inode)
1129                 return 0;
1130
1131         fs_info = btrfs_sb(inode->i_sb);
1132
1133         /* Flush the dirty pages in the cache file. */
1134         ret = flush_dirty_cache(inode);
1135         if (ret)
1136                 goto out;
1137
1138         /* Update the cache item to tell everyone this cache file is valid. */
1139         ret = update_cache_item(trans, root, inode, path, offset,
1140                                 io_ctl->entries, io_ctl->bitmaps);
1141 out:
1142         io_ctl_free(io_ctl);
1143         if (ret) {
1144                 invalidate_inode_pages2(inode->i_mapping);
1145                 BTRFS_I(inode)->generation = 0;
1146                 if (block_group) {
1147 #ifdef DEBUG
1148                         btrfs_err(fs_info,
1149                                   "failed to write free space cache for block group %llu",
1150                                   block_group->key.objectid);
1151 #endif
1152                 }
1153         }
1154         btrfs_update_inode(trans, root, inode);
1155
1156         if (block_group) {
1157                 /* the dirty list is protected by the dirty_bgs_lock */
1158                 spin_lock(&trans->transaction->dirty_bgs_lock);
1159
1160                 /* the disk_cache_state is protected by the block group lock */
1161                 spin_lock(&block_group->lock);
1162
1163                 /*
1164                  * only mark this as written if we didn't get put back on
1165                  * the dirty list while waiting for IO.   Otherwise our
1166                  * cache state won't be right, and we won't get written again
1167                  */
1168                 if (!ret && list_empty(&block_group->dirty_list))
1169                         block_group->disk_cache_state = BTRFS_DC_WRITTEN;
1170                 else if (ret)
1171                         block_group->disk_cache_state = BTRFS_DC_ERROR;
1172
1173                 spin_unlock(&block_group->lock);
1174                 spin_unlock(&trans->transaction->dirty_bgs_lock);
1175                 io_ctl->inode = NULL;
1176                 iput(inode);
1177         }
1178
1179         return ret;
1180
1181 }
1182
1183 static int btrfs_wait_cache_io_root(struct btrfs_root *root,
1184                                     struct btrfs_trans_handle *trans,
1185                                     struct btrfs_io_ctl *io_ctl,
1186                                     struct btrfs_path *path)
1187 {
1188         return __btrfs_wait_cache_io(root, trans, NULL, io_ctl, path, 0);
1189 }
1190
1191 int btrfs_wait_cache_io(struct btrfs_trans_handle *trans,
1192                         struct btrfs_block_group_cache *block_group,
1193                         struct btrfs_path *path)
1194 {
1195         return __btrfs_wait_cache_io(block_group->fs_info->tree_root, trans,
1196                                      block_group, &block_group->io_ctl,
1197                                      path, block_group->key.objectid);
1198 }
1199
1200 /**
1201  * __btrfs_write_out_cache - write out cached info to an inode
1202  * @root - the root the inode belongs to
1203  * @ctl - the free space cache we are going to write out
1204  * @block_group - the block_group for this cache if it belongs to a block_group
1205  * @trans - the trans handle
1206  *
1207  * This function writes out a free space cache struct to disk for quick recovery
1208  * on mount.  This will return 0 if it was successful in writing the cache out,
1209  * or an errno if it was not.
1210  */
1211 static int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
1212                                    struct btrfs_free_space_ctl *ctl,
1213                                    struct btrfs_block_group_cache *block_group,
1214                                    struct btrfs_io_ctl *io_ctl,
1215                                    struct btrfs_trans_handle *trans)
1216 {
1217         struct btrfs_fs_info *fs_info = root->fs_info;
1218         struct extent_state *cached_state = NULL;
1219         LIST_HEAD(bitmap_list);
1220         int entries = 0;
1221         int bitmaps = 0;
1222         int ret;
1223         int must_iput = 0;
1224
1225         if (!i_size_read(inode))
1226                 return -EIO;
1227
1228         WARN_ON(io_ctl->pages);
1229         ret = io_ctl_init(io_ctl, inode, 1);
1230         if (ret)
1231                 return ret;
1232
1233         if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA)) {
1234                 down_write(&block_group->data_rwsem);
1235                 spin_lock(&block_group->lock);
1236                 if (block_group->delalloc_bytes) {
1237                         block_group->disk_cache_state = BTRFS_DC_WRITTEN;
1238                         spin_unlock(&block_group->lock);
1239                         up_write(&block_group->data_rwsem);
1240                         BTRFS_I(inode)->generation = 0;
1241                         ret = 0;
1242                         must_iput = 1;
1243                         goto out;
1244                 }
1245                 spin_unlock(&block_group->lock);
1246         }
1247
1248         /* Lock all pages first so we can lock the extent safely. */
1249         ret = io_ctl_prepare_pages(io_ctl, inode, 0);
1250         if (ret)
1251                 goto out_unlock;
1252
1253         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
1254                          &cached_state);
1255
1256         io_ctl_set_generation(io_ctl, trans->transid);
1257
1258         mutex_lock(&ctl->cache_writeout_mutex);
1259         /* Write out the extent entries in the free space cache */
1260         spin_lock(&ctl->tree_lock);
1261         ret = write_cache_extent_entries(io_ctl, ctl,
1262                                          block_group, &entries, &bitmaps,
1263                                          &bitmap_list);
1264         if (ret)
1265                 goto out_nospc_locked;
1266
1267         /*
1268          * Some spaces that are freed in the current transaction are pinned,
1269          * they will be added into free space cache after the transaction is
1270          * committed, we shouldn't lose them.
1271          *
1272          * If this changes while we are working we'll get added back to
1273          * the dirty list and redo it.  No locking needed
1274          */
1275         ret = write_pinned_extent_entries(fs_info, block_group,
1276                                           io_ctl, &entries);
1277         if (ret)
1278                 goto out_nospc_locked;
1279
1280         /*
1281          * At last, we write out all the bitmaps and keep cache_writeout_mutex
1282          * locked while doing it because a concurrent trim can be manipulating
1283          * or freeing the bitmap.
1284          */
1285         ret = write_bitmap_entries(io_ctl, &bitmap_list);
1286         spin_unlock(&ctl->tree_lock);
1287         mutex_unlock(&ctl->cache_writeout_mutex);
1288         if (ret)
1289                 goto out_nospc;
1290
1291         /* Zero out the rest of the pages just to make sure */
1292         io_ctl_zero_remaining_pages(io_ctl);
1293
1294         /* Everything is written out, now we dirty the pages in the file. */
1295         ret = btrfs_dirty_pages(inode, io_ctl->pages, io_ctl->num_pages, 0,
1296                                 i_size_read(inode), &cached_state);
1297         if (ret)
1298                 goto out_nospc;
1299
1300         if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA))
1301                 up_write(&block_group->data_rwsem);
1302         /*
1303          * Release the pages and unlock the extent, we will flush
1304          * them out later
1305          */
1306         io_ctl_drop_pages(io_ctl);
1307
1308         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
1309                              i_size_read(inode) - 1, &cached_state);
1310
1311         /*
1312          * at this point the pages are under IO and we're happy,
1313          * The caller is responsible for waiting on them and updating the
1314          * the cache and the inode
1315          */
1316         io_ctl->entries = entries;
1317         io_ctl->bitmaps = bitmaps;
1318
1319         ret = btrfs_fdatawrite_range(inode, 0, (u64)-1);
1320         if (ret)
1321                 goto out;
1322
1323         return 0;
1324
1325 out:
1326         io_ctl->inode = NULL;
1327         io_ctl_free(io_ctl);
1328         if (ret) {
1329                 invalidate_inode_pages2(inode->i_mapping);
1330                 BTRFS_I(inode)->generation = 0;
1331         }
1332         btrfs_update_inode(trans, root, inode);
1333         if (must_iput)
1334                 iput(inode);
1335         return ret;
1336
1337 out_nospc_locked:
1338         cleanup_bitmap_list(&bitmap_list);
1339         spin_unlock(&ctl->tree_lock);
1340         mutex_unlock(&ctl->cache_writeout_mutex);
1341
1342 out_nospc:
1343         cleanup_write_cache_enospc(inode, io_ctl, &cached_state);
1344
1345 out_unlock:
1346         if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA))
1347                 up_write(&block_group->data_rwsem);
1348
1349         goto out;
1350 }
1351
1352 int btrfs_write_out_cache(struct btrfs_fs_info *fs_info,
1353                           struct btrfs_trans_handle *trans,
1354                           struct btrfs_block_group_cache *block_group,
1355                           struct btrfs_path *path)
1356 {
1357         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1358         struct inode *inode;
1359         int ret = 0;
1360
1361         spin_lock(&block_group->lock);
1362         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
1363                 spin_unlock(&block_group->lock);
1364                 return 0;
1365         }
1366         spin_unlock(&block_group->lock);
1367
1368         inode = lookup_free_space_inode(fs_info, block_group, path);
1369         if (IS_ERR(inode))
1370                 return 0;
1371
1372         ret = __btrfs_write_out_cache(fs_info->tree_root, inode, ctl,
1373                                 block_group, &block_group->io_ctl, trans);
1374         if (ret) {
1375 #ifdef DEBUG
1376                 btrfs_err(fs_info,
1377                           "failed to write free space cache for block group %llu",
1378                           block_group->key.objectid);
1379 #endif
1380                 spin_lock(&block_group->lock);
1381                 block_group->disk_cache_state = BTRFS_DC_ERROR;
1382                 spin_unlock(&block_group->lock);
1383
1384                 block_group->io_ctl.inode = NULL;
1385                 iput(inode);
1386         }
1387
1388         /*
1389          * if ret == 0 the caller is expected to call btrfs_wait_cache_io
1390          * to wait for IO and put the inode
1391          */
1392
1393         return ret;
1394 }
1395
1396 static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
1397                                           u64 offset)
1398 {
1399         ASSERT(offset >= bitmap_start);
1400         offset -= bitmap_start;
1401         return (unsigned long)(div_u64(offset, unit));
1402 }
1403
1404 static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
1405 {
1406         return (unsigned long)(div_u64(bytes, unit));
1407 }
1408
1409 static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
1410                                    u64 offset)
1411 {
1412         u64 bitmap_start;
1413         u64 bytes_per_bitmap;
1414
1415         bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
1416         bitmap_start = offset - ctl->start;
1417         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
1418         bitmap_start *= bytes_per_bitmap;
1419         bitmap_start += ctl->start;
1420
1421         return bitmap_start;
1422 }
1423
1424 static int tree_insert_offset(struct rb_root *root, u64 offset,
1425                               struct rb_node *node, int bitmap)
1426 {
1427         struct rb_node **p = &root->rb_node;
1428         struct rb_node *parent = NULL;
1429         struct btrfs_free_space *info;
1430
1431         while (*p) {
1432                 parent = *p;
1433                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
1434
1435                 if (offset < info->offset) {
1436                         p = &(*p)->rb_left;
1437                 } else if (offset > info->offset) {
1438                         p = &(*p)->rb_right;
1439                 } else {
1440                         /*
1441                          * we could have a bitmap entry and an extent entry
1442                          * share the same offset.  If this is the case, we want
1443                          * the extent entry to always be found first if we do a
1444                          * linear search through the tree, since we want to have
1445                          * the quickest allocation time, and allocating from an
1446                          * extent is faster than allocating from a bitmap.  So
1447                          * if we're inserting a bitmap and we find an entry at
1448                          * this offset, we want to go right, or after this entry
1449                          * logically.  If we are inserting an extent and we've
1450                          * found a bitmap, we want to go left, or before
1451                          * logically.
1452                          */
1453                         if (bitmap) {
1454                                 if (info->bitmap) {
1455                                         WARN_ON_ONCE(1);
1456                                         return -EEXIST;
1457                                 }
1458                                 p = &(*p)->rb_right;
1459                         } else {
1460                                 if (!info->bitmap) {
1461                                         WARN_ON_ONCE(1);
1462                                         return -EEXIST;
1463                                 }
1464                                 p = &(*p)->rb_left;
1465                         }
1466                 }
1467         }
1468
1469         rb_link_node(node, parent, p);
1470         rb_insert_color(node, root);
1471
1472         return 0;
1473 }
1474
1475 /*
1476  * searches the tree for the given offset.
1477  *
1478  * fuzzy - If this is set, then we are trying to make an allocation, and we just
1479  * want a section that has at least bytes size and comes at or after the given
1480  * offset.
1481  */
1482 static struct btrfs_free_space *
1483 tree_search_offset(struct btrfs_free_space_ctl *ctl,
1484                    u64 offset, int bitmap_only, int fuzzy)
1485 {
1486         struct rb_node *n = ctl->free_space_offset.rb_node;
1487         struct btrfs_free_space *entry, *prev = NULL;
1488
1489         /* find entry that is closest to the 'offset' */
1490         while (1) {
1491                 if (!n) {
1492                         entry = NULL;
1493                         break;
1494                 }
1495
1496                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1497                 prev = entry;
1498
1499                 if (offset < entry->offset)
1500                         n = n->rb_left;
1501                 else if (offset > entry->offset)
1502                         n = n->rb_right;
1503                 else
1504                         break;
1505         }
1506
1507         if (bitmap_only) {
1508                 if (!entry)
1509                         return NULL;
1510                 if (entry->bitmap)
1511                         return entry;
1512
1513                 /*
1514                  * bitmap entry and extent entry may share same offset,
1515                  * in that case, bitmap entry comes after extent entry.
1516                  */
1517                 n = rb_next(n);
1518                 if (!n)
1519                         return NULL;
1520                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1521                 if (entry->offset != offset)
1522                         return NULL;
1523
1524                 WARN_ON(!entry->bitmap);
1525                 return entry;
1526         } else if (entry) {
1527                 if (entry->bitmap) {
1528                         /*
1529                          * if previous extent entry covers the offset,
1530                          * we should return it instead of the bitmap entry
1531                          */
1532                         n = rb_prev(&entry->offset_index);
1533                         if (n) {
1534                                 prev = rb_entry(n, struct btrfs_free_space,
1535                                                 offset_index);
1536                                 if (!prev->bitmap &&
1537                                     prev->offset + prev->bytes > offset)
1538                                         entry = prev;
1539                         }
1540                 }
1541                 return entry;
1542         }
1543
1544         if (!prev)
1545                 return NULL;
1546
1547         /* find last entry before the 'offset' */
1548         entry = prev;
1549         if (entry->offset > offset) {
1550                 n = rb_prev(&entry->offset_index);
1551                 if (n) {
1552                         entry = rb_entry(n, struct btrfs_free_space,
1553                                         offset_index);
1554                         ASSERT(entry->offset <= offset);
1555                 } else {
1556                         if (fuzzy)
1557                                 return entry;
1558                         else
1559                                 return NULL;
1560                 }
1561         }
1562
1563         if (entry->bitmap) {
1564                 n = rb_prev(&entry->offset_index);
1565                 if (n) {
1566                         prev = rb_entry(n, struct btrfs_free_space,
1567                                         offset_index);
1568                         if (!prev->bitmap &&
1569                             prev->offset + prev->bytes > offset)
1570                                 return prev;
1571                 }
1572                 if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1573                         return entry;
1574         } else if (entry->offset + entry->bytes > offset)
1575                 return entry;
1576
1577         if (!fuzzy)
1578                 return NULL;
1579
1580         while (1) {
1581                 if (entry->bitmap) {
1582                         if (entry->offset + BITS_PER_BITMAP *
1583                             ctl->unit > offset)
1584                                 break;
1585                 } else {
1586                         if (entry->offset + entry->bytes > offset)
1587                                 break;
1588                 }
1589
1590                 n = rb_next(&entry->offset_index);
1591                 if (!n)
1592                         return NULL;
1593                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1594         }
1595         return entry;
1596 }
1597
1598 static inline void
1599 __unlink_free_space(struct btrfs_free_space_ctl *ctl,
1600                     struct btrfs_free_space *info)
1601 {
1602         rb_erase(&info->offset_index, &ctl->free_space_offset);
1603         ctl->free_extents--;
1604 }
1605
1606 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1607                               struct btrfs_free_space *info)
1608 {
1609         __unlink_free_space(ctl, info);
1610         ctl->free_space -= info->bytes;
1611 }
1612
1613 static int link_free_space(struct btrfs_free_space_ctl *ctl,
1614                            struct btrfs_free_space *info)
1615 {
1616         int ret = 0;
1617
1618         ASSERT(info->bytes || info->bitmap);
1619         ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1620                                  &info->offset_index, (info->bitmap != NULL));
1621         if (ret)
1622                 return ret;
1623
1624         ctl->free_space += info->bytes;
1625         ctl->free_extents++;
1626         return ret;
1627 }
1628
1629 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1630 {
1631         struct btrfs_block_group_cache *block_group = ctl->private;
1632         u64 max_bytes;
1633         u64 bitmap_bytes;
1634         u64 extent_bytes;
1635         u64 size = block_group->key.offset;
1636         u64 bytes_per_bg = BITS_PER_BITMAP * ctl->unit;
1637         u64 max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1638
1639         max_bitmaps = max_t(u64, max_bitmaps, 1);
1640
1641         ASSERT(ctl->total_bitmaps <= max_bitmaps);
1642
1643         /*
1644          * The goal is to keep the total amount of memory used per 1gb of space
1645          * at or below 32k, so we need to adjust how much memory we allow to be
1646          * used by extent based free space tracking
1647          */
1648         if (size < SZ_1G)
1649                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1650         else
1651                 max_bytes = MAX_CACHE_BYTES_PER_GIG * div_u64(size, SZ_1G);
1652
1653         /*
1654          * we want to account for 1 more bitmap than what we have so we can make
1655          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1656          * we add more bitmaps.
1657          */
1658         bitmap_bytes = (ctl->total_bitmaps + 1) * ctl->unit;
1659
1660         if (bitmap_bytes >= max_bytes) {
1661                 ctl->extents_thresh = 0;
1662                 return;
1663         }
1664
1665         /*
1666          * we want the extent entry threshold to always be at most 1/2 the max
1667          * bytes we can have, or whatever is less than that.
1668          */
1669         extent_bytes = max_bytes - bitmap_bytes;
1670         extent_bytes = min_t(u64, extent_bytes, max_bytes >> 1);
1671
1672         ctl->extents_thresh =
1673                 div_u64(extent_bytes, sizeof(struct btrfs_free_space));
1674 }
1675
1676 static inline void __bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1677                                        struct btrfs_free_space *info,
1678                                        u64 offset, u64 bytes)
1679 {
1680         unsigned long start, count;
1681
1682         start = offset_to_bit(info->offset, ctl->unit, offset);
1683         count = bytes_to_bits(bytes, ctl->unit);
1684         ASSERT(start + count <= BITS_PER_BITMAP);
1685
1686         bitmap_clear(info->bitmap, start, count);
1687
1688         info->bytes -= bytes;
1689 }
1690
1691 static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1692                               struct btrfs_free_space *info, u64 offset,
1693                               u64 bytes)
1694 {
1695         __bitmap_clear_bits(ctl, info, offset, bytes);
1696         ctl->free_space -= bytes;
1697 }
1698
1699 static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1700                             struct btrfs_free_space *info, u64 offset,
1701                             u64 bytes)
1702 {
1703         unsigned long start, count;
1704
1705         start = offset_to_bit(info->offset, ctl->unit, offset);
1706         count = bytes_to_bits(bytes, ctl->unit);
1707         ASSERT(start + count <= BITS_PER_BITMAP);
1708
1709         bitmap_set(info->bitmap, start, count);
1710
1711         info->bytes += bytes;
1712         ctl->free_space += bytes;
1713 }
1714
1715 /*
1716  * If we can not find suitable extent, we will use bytes to record
1717  * the size of the max extent.
1718  */
1719 static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1720                          struct btrfs_free_space *bitmap_info, u64 *offset,
1721                          u64 *bytes, bool for_alloc)
1722 {
1723         unsigned long found_bits = 0;
1724         unsigned long max_bits = 0;
1725         unsigned long bits, i;
1726         unsigned long next_zero;
1727         unsigned long extent_bits;
1728
1729         /*
1730          * Skip searching the bitmap if we don't have a contiguous section that
1731          * is large enough for this allocation.
1732          */
1733         if (for_alloc &&
1734             bitmap_info->max_extent_size &&
1735             bitmap_info->max_extent_size < *bytes) {
1736                 *bytes = bitmap_info->max_extent_size;
1737                 return -1;
1738         }
1739
1740         i = offset_to_bit(bitmap_info->offset, ctl->unit,
1741                           max_t(u64, *offset, bitmap_info->offset));
1742         bits = bytes_to_bits(*bytes, ctl->unit);
1743
1744         for_each_set_bit_from(i, bitmap_info->bitmap, BITS_PER_BITMAP) {
1745                 if (for_alloc && bits == 1) {
1746                         found_bits = 1;
1747                         break;
1748                 }
1749                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1750                                                BITS_PER_BITMAP, i);
1751                 extent_bits = next_zero - i;
1752                 if (extent_bits >= bits) {
1753                         found_bits = extent_bits;
1754                         break;
1755                 } else if (extent_bits > max_bits) {
1756                         max_bits = extent_bits;
1757                 }
1758                 i = next_zero;
1759         }
1760
1761         if (found_bits) {
1762                 *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1763                 *bytes = (u64)(found_bits) * ctl->unit;
1764                 return 0;
1765         }
1766
1767         *bytes = (u64)(max_bits) * ctl->unit;
1768         bitmap_info->max_extent_size = *bytes;
1769         return -1;
1770 }
1771
1772 /* Cache the size of the max extent in bytes */
1773 static struct btrfs_free_space *
1774 find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes,
1775                 unsigned long align, u64 *max_extent_size)
1776 {
1777         struct btrfs_free_space *entry;
1778         struct rb_node *node;
1779         u64 tmp;
1780         u64 align_off;
1781         int ret;
1782
1783         if (!ctl->free_space_offset.rb_node)
1784                 goto out;
1785
1786         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1787         if (!entry)
1788                 goto out;
1789
1790         for (node = &entry->offset_index; node; node = rb_next(node)) {
1791                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1792                 if (entry->bytes < *bytes) {
1793                         if (entry->bytes > *max_extent_size)
1794                                 *max_extent_size = entry->bytes;
1795                         continue;
1796                 }
1797
1798                 /* make sure the space returned is big enough
1799                  * to match our requested alignment
1800                  */
1801                 if (*bytes >= align) {
1802                         tmp = entry->offset - ctl->start + align - 1;
1803                         tmp = div64_u64(tmp, align);
1804                         tmp = tmp * align + ctl->start;
1805                         align_off = tmp - entry->offset;
1806                 } else {
1807                         align_off = 0;
1808                         tmp = entry->offset;
1809                 }
1810
1811                 if (entry->bytes < *bytes + align_off) {
1812                         if (entry->bytes > *max_extent_size)
1813                                 *max_extent_size = entry->bytes;
1814                         continue;
1815                 }
1816
1817                 if (entry->bitmap) {
1818                         u64 size = *bytes;
1819
1820                         ret = search_bitmap(ctl, entry, &tmp, &size, true);
1821                         if (!ret) {
1822                                 *offset = tmp;
1823                                 *bytes = size;
1824                                 return entry;
1825                         } else if (size > *max_extent_size) {
1826                                 *max_extent_size = size;
1827                         }
1828                         continue;
1829                 }
1830
1831                 *offset = tmp;
1832                 *bytes = entry->bytes - align_off;
1833                 return entry;
1834         }
1835 out:
1836         return NULL;
1837 }
1838
1839 static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1840                            struct btrfs_free_space *info, u64 offset)
1841 {
1842         info->offset = offset_to_bitmap(ctl, offset);
1843         info->bytes = 0;
1844         INIT_LIST_HEAD(&info->list);
1845         link_free_space(ctl, info);
1846         ctl->total_bitmaps++;
1847
1848         ctl->op->recalc_thresholds(ctl);
1849 }
1850
1851 static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1852                         struct btrfs_free_space *bitmap_info)
1853 {
1854         unlink_free_space(ctl, bitmap_info);
1855         kfree(bitmap_info->bitmap);
1856         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1857         ctl->total_bitmaps--;
1858         ctl->op->recalc_thresholds(ctl);
1859 }
1860
1861 static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1862                               struct btrfs_free_space *bitmap_info,
1863                               u64 *offset, u64 *bytes)
1864 {
1865         u64 end;
1866         u64 search_start, search_bytes;
1867         int ret;
1868
1869 again:
1870         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1871
1872         /*
1873          * We need to search for bits in this bitmap.  We could only cover some
1874          * of the extent in this bitmap thanks to how we add space, so we need
1875          * to search for as much as it as we can and clear that amount, and then
1876          * go searching for the next bit.
1877          */
1878         search_start = *offset;
1879         search_bytes = ctl->unit;
1880         search_bytes = min(search_bytes, end - search_start + 1);
1881         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes,
1882                             false);
1883         if (ret < 0 || search_start != *offset)
1884                 return -EINVAL;
1885
1886         /* We may have found more bits than what we need */
1887         search_bytes = min(search_bytes, *bytes);
1888
1889         /* Cannot clear past the end of the bitmap */
1890         search_bytes = min(search_bytes, end - search_start + 1);
1891
1892         bitmap_clear_bits(ctl, bitmap_info, search_start, search_bytes);
1893         *offset += search_bytes;
1894         *bytes -= search_bytes;
1895
1896         if (*bytes) {
1897                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1898                 if (!bitmap_info->bytes)
1899                         free_bitmap(ctl, bitmap_info);
1900
1901                 /*
1902                  * no entry after this bitmap, but we still have bytes to
1903                  * remove, so something has gone wrong.
1904                  */
1905                 if (!next)
1906                         return -EINVAL;
1907
1908                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1909                                        offset_index);
1910
1911                 /*
1912                  * if the next entry isn't a bitmap we need to return to let the
1913                  * extent stuff do its work.
1914                  */
1915                 if (!bitmap_info->bitmap)
1916                         return -EAGAIN;
1917
1918                 /*
1919                  * Ok the next item is a bitmap, but it may not actually hold
1920                  * the information for the rest of this free space stuff, so
1921                  * look for it, and if we don't find it return so we can try
1922                  * everything over again.
1923                  */
1924                 search_start = *offset;
1925                 search_bytes = ctl->unit;
1926                 ret = search_bitmap(ctl, bitmap_info, &search_start,
1927                                     &search_bytes, false);
1928                 if (ret < 0 || search_start != *offset)
1929                         return -EAGAIN;
1930
1931                 goto again;
1932         } else if (!bitmap_info->bytes)
1933                 free_bitmap(ctl, bitmap_info);
1934
1935         return 0;
1936 }
1937
1938 static u64 add_bytes_to_bitmap(struct btrfs_free_space_ctl *ctl,
1939                                struct btrfs_free_space *info, u64 offset,
1940                                u64 bytes)
1941 {
1942         u64 bytes_to_set = 0;
1943         u64 end;
1944
1945         end = info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1946
1947         bytes_to_set = min(end - offset, bytes);
1948
1949         bitmap_set_bits(ctl, info, offset, bytes_to_set);
1950
1951         /*
1952          * We set some bytes, we have no idea what the max extent size is
1953          * anymore.
1954          */
1955         info->max_extent_size = 0;
1956
1957         return bytes_to_set;
1958
1959 }
1960
1961 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1962                       struct btrfs_free_space *info)
1963 {
1964         struct btrfs_block_group_cache *block_group = ctl->private;
1965         struct btrfs_fs_info *fs_info = block_group->fs_info;
1966         bool forced = false;
1967
1968 #ifdef CONFIG_BTRFS_DEBUG
1969         if (btrfs_should_fragment_free_space(block_group))
1970                 forced = true;
1971 #endif
1972
1973         /*
1974          * If we are below the extents threshold then we can add this as an
1975          * extent, and don't have to deal with the bitmap
1976          */
1977         if (!forced && ctl->free_extents < ctl->extents_thresh) {
1978                 /*
1979                  * If this block group has some small extents we don't want to
1980                  * use up all of our free slots in the cache with them, we want
1981                  * to reserve them to larger extents, however if we have plenty
1982                  * of cache left then go ahead an dadd them, no sense in adding
1983                  * the overhead of a bitmap if we don't have to.
1984                  */
1985                 if (info->bytes <= fs_info->sectorsize * 4) {
1986                         if (ctl->free_extents * 2 <= ctl->extents_thresh)
1987                                 return false;
1988                 } else {
1989                         return false;
1990                 }
1991         }
1992
1993         /*
1994          * The original block groups from mkfs can be really small, like 8
1995          * megabytes, so don't bother with a bitmap for those entries.  However
1996          * some block groups can be smaller than what a bitmap would cover but
1997          * are still large enough that they could overflow the 32k memory limit,
1998          * so allow those block groups to still be allowed to have a bitmap
1999          * entry.
2000          */
2001         if (((BITS_PER_BITMAP * ctl->unit) >> 1) > block_group->key.offset)
2002                 return false;
2003
2004         return true;
2005 }
2006
2007 static const struct btrfs_free_space_op free_space_op = {
2008         .recalc_thresholds      = recalculate_thresholds,
2009         .use_bitmap             = use_bitmap,
2010 };
2011
2012 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
2013                               struct btrfs_free_space *info)
2014 {
2015         struct btrfs_free_space *bitmap_info;
2016         struct btrfs_block_group_cache *block_group = NULL;
2017         int added = 0;
2018         u64 bytes, offset, bytes_added;
2019         int ret;
2020
2021         bytes = info->bytes;
2022         offset = info->offset;
2023
2024         if (!ctl->op->use_bitmap(ctl, info))
2025                 return 0;
2026
2027         if (ctl->op == &free_space_op)
2028                 block_group = ctl->private;
2029 again:
2030         /*
2031          * Since we link bitmaps right into the cluster we need to see if we
2032          * have a cluster here, and if so and it has our bitmap we need to add
2033          * the free space to that bitmap.
2034          */
2035         if (block_group && !list_empty(&block_group->cluster_list)) {
2036                 struct btrfs_free_cluster *cluster;
2037                 struct rb_node *node;
2038                 struct btrfs_free_space *entry;
2039
2040                 cluster = list_entry(block_group->cluster_list.next,
2041                                      struct btrfs_free_cluster,
2042                                      block_group_list);
2043                 spin_lock(&cluster->lock);
2044                 node = rb_first(&cluster->root);
2045                 if (!node) {
2046                         spin_unlock(&cluster->lock);
2047                         goto no_cluster_bitmap;
2048                 }
2049
2050                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2051                 if (!entry->bitmap) {
2052                         spin_unlock(&cluster->lock);
2053                         goto no_cluster_bitmap;
2054                 }
2055
2056                 if (entry->offset == offset_to_bitmap(ctl, offset)) {
2057                         bytes_added = add_bytes_to_bitmap(ctl, entry,
2058                                                           offset, bytes);
2059                         bytes -= bytes_added;
2060                         offset += bytes_added;
2061                 }
2062                 spin_unlock(&cluster->lock);
2063                 if (!bytes) {
2064                         ret = 1;
2065                         goto out;
2066                 }
2067         }
2068
2069 no_cluster_bitmap:
2070         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
2071                                          1, 0);
2072         if (!bitmap_info) {
2073                 ASSERT(added == 0);
2074                 goto new_bitmap;
2075         }
2076
2077         bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
2078         bytes -= bytes_added;
2079         offset += bytes_added;
2080         added = 0;
2081
2082         if (!bytes) {
2083                 ret = 1;
2084                 goto out;
2085         } else
2086                 goto again;
2087
2088 new_bitmap:
2089         if (info && info->bitmap) {
2090                 add_new_bitmap(ctl, info, offset);
2091                 added = 1;
2092                 info = NULL;
2093                 goto again;
2094         } else {
2095                 spin_unlock(&ctl->tree_lock);
2096
2097                 /* no pre-allocated info, allocate a new one */
2098                 if (!info) {
2099                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
2100                                                  GFP_NOFS);
2101                         if (!info) {
2102                                 spin_lock(&ctl->tree_lock);
2103                                 ret = -ENOMEM;
2104                                 goto out;
2105                         }
2106                 }
2107
2108                 /* allocate the bitmap */
2109                 info->bitmap = kzalloc(PAGE_SIZE, GFP_NOFS);
2110                 spin_lock(&ctl->tree_lock);
2111                 if (!info->bitmap) {
2112                         ret = -ENOMEM;
2113                         goto out;
2114                 }
2115                 goto again;
2116         }
2117
2118 out:
2119         if (info) {
2120                 if (info->bitmap)
2121                         kfree(info->bitmap);
2122                 kmem_cache_free(btrfs_free_space_cachep, info);
2123         }
2124
2125         return ret;
2126 }
2127
2128 static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
2129                           struct btrfs_free_space *info, bool update_stat)
2130 {
2131         struct btrfs_free_space *left_info;
2132         struct btrfs_free_space *right_info;
2133         bool merged = false;
2134         u64 offset = info->offset;
2135         u64 bytes = info->bytes;
2136
2137         /*
2138          * first we want to see if there is free space adjacent to the range we
2139          * are adding, if there is remove that struct and add a new one to
2140          * cover the entire range
2141          */
2142         right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
2143         if (right_info && rb_prev(&right_info->offset_index))
2144                 left_info = rb_entry(rb_prev(&right_info->offset_index),
2145                                      struct btrfs_free_space, offset_index);
2146         else
2147                 left_info = tree_search_offset(ctl, offset - 1, 0, 0);
2148
2149         if (right_info && !right_info->bitmap) {
2150                 if (update_stat)
2151                         unlink_free_space(ctl, right_info);
2152                 else
2153                         __unlink_free_space(ctl, right_info);
2154                 info->bytes += right_info->bytes;
2155                 kmem_cache_free(btrfs_free_space_cachep, right_info);
2156                 merged = true;
2157         }
2158
2159         if (left_info && !left_info->bitmap &&
2160             left_info->offset + left_info->bytes == offset) {
2161                 if (update_stat)
2162                         unlink_free_space(ctl, left_info);
2163                 else
2164                         __unlink_free_space(ctl, left_info);
2165                 info->offset = left_info->offset;
2166                 info->bytes += left_info->bytes;
2167                 kmem_cache_free(btrfs_free_space_cachep, left_info);
2168                 merged = true;
2169         }
2170
2171         return merged;
2172 }
2173
2174 static bool steal_from_bitmap_to_end(struct btrfs_free_space_ctl *ctl,
2175                                      struct btrfs_free_space *info,
2176                                      bool update_stat)
2177 {
2178         struct btrfs_free_space *bitmap;
2179         unsigned long i;
2180         unsigned long j;
2181         const u64 end = info->offset + info->bytes;
2182         const u64 bitmap_offset = offset_to_bitmap(ctl, end);
2183         u64 bytes;
2184
2185         bitmap = tree_search_offset(ctl, bitmap_offset, 1, 0);
2186         if (!bitmap)
2187                 return false;
2188
2189         i = offset_to_bit(bitmap->offset, ctl->unit, end);
2190         j = find_next_zero_bit(bitmap->bitmap, BITS_PER_BITMAP, i);
2191         if (j == i)
2192                 return false;
2193         bytes = (j - i) * ctl->unit;
2194         info->bytes += bytes;
2195
2196         if (update_stat)
2197                 bitmap_clear_bits(ctl, bitmap, end, bytes);
2198         else
2199                 __bitmap_clear_bits(ctl, bitmap, end, bytes);
2200
2201         if (!bitmap->bytes)
2202                 free_bitmap(ctl, bitmap);
2203
2204         return true;
2205 }
2206
2207 static bool steal_from_bitmap_to_front(struct btrfs_free_space_ctl *ctl,
2208                                        struct btrfs_free_space *info,
2209                                        bool update_stat)
2210 {
2211         struct btrfs_free_space *bitmap;
2212         u64 bitmap_offset;
2213         unsigned long i;
2214         unsigned long j;
2215         unsigned long prev_j;
2216         u64 bytes;
2217
2218         bitmap_offset = offset_to_bitmap(ctl, info->offset);
2219         /* If we're on a boundary, try the previous logical bitmap. */
2220         if (bitmap_offset == info->offset) {
2221                 if (info->offset == 0)
2222                         return false;
2223                 bitmap_offset = offset_to_bitmap(ctl, info->offset - 1);
2224         }
2225
2226         bitmap = tree_search_offset(ctl, bitmap_offset, 1, 0);
2227         if (!bitmap)
2228                 return false;
2229
2230         i = offset_to_bit(bitmap->offset, ctl->unit, info->offset) - 1;
2231         j = 0;
2232         prev_j = (unsigned long)-1;
2233         for_each_clear_bit_from(j, bitmap->bitmap, BITS_PER_BITMAP) {
2234                 if (j > i)
2235                         break;
2236                 prev_j = j;
2237         }
2238         if (prev_j == i)
2239                 return false;
2240
2241         if (prev_j == (unsigned long)-1)
2242                 bytes = (i + 1) * ctl->unit;
2243         else
2244                 bytes = (i - prev_j) * ctl->unit;
2245
2246         info->offset -= bytes;
2247         info->bytes += bytes;
2248
2249         if (update_stat)
2250                 bitmap_clear_bits(ctl, bitmap, info->offset, bytes);
2251         else
2252                 __bitmap_clear_bits(ctl, bitmap, info->offset, bytes);
2253
2254         if (!bitmap->bytes)
2255                 free_bitmap(ctl, bitmap);
2256
2257         return true;
2258 }
2259
2260 /*
2261  * We prefer always to allocate from extent entries, both for clustered and
2262  * non-clustered allocation requests. So when attempting to add a new extent
2263  * entry, try to see if there's adjacent free space in bitmap entries, and if
2264  * there is, migrate that space from the bitmaps to the extent.
2265  * Like this we get better chances of satisfying space allocation requests
2266  * because we attempt to satisfy them based on a single cache entry, and never
2267  * on 2 or more entries - even if the entries represent a contiguous free space
2268  * region (e.g. 1 extent entry + 1 bitmap entry starting where the extent entry
2269  * ends).
2270  */
2271 static void steal_from_bitmap(struct btrfs_free_space_ctl *ctl,
2272                               struct btrfs_free_space *info,
2273                               bool update_stat)
2274 {
2275         /*
2276          * Only work with disconnected entries, as we can change their offset,
2277          * and must be extent entries.
2278          */
2279         ASSERT(!info->bitmap);
2280         ASSERT(RB_EMPTY_NODE(&info->offset_index));
2281
2282         if (ctl->total_bitmaps > 0) {
2283                 bool stole_end;
2284                 bool stole_front = false;
2285
2286                 stole_end = steal_from_bitmap_to_end(ctl, info, update_stat);
2287                 if (ctl->total_bitmaps > 0)
2288                         stole_front = steal_from_bitmap_to_front(ctl, info,
2289                                                                  update_stat);
2290
2291                 if (stole_end || stole_front)
2292                         try_merge_free_space(ctl, info, update_stat);
2293         }
2294 }
2295
2296 int __btrfs_add_free_space(struct btrfs_fs_info *fs_info,
2297                            struct btrfs_free_space_ctl *ctl,
2298                            u64 offset, u64 bytes)
2299 {
2300         struct btrfs_free_space *info;
2301         int ret = 0;
2302
2303         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
2304         if (!info)
2305                 return -ENOMEM;
2306
2307         info->offset = offset;
2308         info->bytes = bytes;
2309         RB_CLEAR_NODE(&info->offset_index);
2310
2311         spin_lock(&ctl->tree_lock);
2312
2313         if (try_merge_free_space(ctl, info, true))
2314                 goto link;
2315
2316         /*
2317          * There was no extent directly to the left or right of this new
2318          * extent then we know we're going to have to allocate a new extent, so
2319          * before we do that see if we need to drop this into a bitmap
2320          */
2321         ret = insert_into_bitmap(ctl, info);
2322         if (ret < 0) {
2323                 goto out;
2324         } else if (ret) {
2325                 ret = 0;
2326                 goto out;
2327         }
2328 link:
2329         /*
2330          * Only steal free space from adjacent bitmaps if we're sure we're not
2331          * going to add the new free space to existing bitmap entries - because
2332          * that would mean unnecessary work that would be reverted. Therefore
2333          * attempt to steal space from bitmaps if we're adding an extent entry.
2334          */
2335         steal_from_bitmap(ctl, info, true);
2336
2337         ret = link_free_space(ctl, info);
2338         if (ret)
2339                 kmem_cache_free(btrfs_free_space_cachep, info);
2340 out:
2341         spin_unlock(&ctl->tree_lock);
2342
2343         if (ret) {
2344                 btrfs_crit(fs_info, "unable to add free space :%d", ret);
2345                 ASSERT(ret != -EEXIST);
2346         }
2347
2348         return ret;
2349 }
2350
2351 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
2352                             u64 offset, u64 bytes)
2353 {
2354         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2355         struct btrfs_free_space *info;
2356         int ret;
2357         bool re_search = false;
2358
2359         spin_lock(&ctl->tree_lock);
2360
2361 again:
2362         ret = 0;
2363         if (!bytes)
2364                 goto out_lock;
2365
2366         info = tree_search_offset(ctl, offset, 0, 0);
2367         if (!info) {
2368                 /*
2369                  * oops didn't find an extent that matched the space we wanted
2370                  * to remove, look for a bitmap instead
2371                  */
2372                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
2373                                           1, 0);
2374                 if (!info) {
2375                         /*
2376                          * If we found a partial bit of our free space in a
2377                          * bitmap but then couldn't find the other part this may
2378                          * be a problem, so WARN about it.
2379                          */
2380                         WARN_ON(re_search);
2381                         goto out_lock;
2382                 }
2383         }
2384
2385         re_search = false;
2386         if (!info->bitmap) {
2387                 unlink_free_space(ctl, info);
2388                 if (offset == info->offset) {
2389                         u64 to_free = min(bytes, info->bytes);
2390
2391                         info->bytes -= to_free;
2392                         info->offset += to_free;
2393                         if (info->bytes) {
2394                                 ret = link_free_space(ctl, info);
2395                                 WARN_ON(ret);
2396                         } else {
2397                                 kmem_cache_free(btrfs_free_space_cachep, info);
2398                         }
2399
2400                         offset += to_free;
2401                         bytes -= to_free;
2402                         goto again;
2403                 } else {
2404                         u64 old_end = info->bytes + info->offset;
2405
2406                         info->bytes = offset - info->offset;
2407                         ret = link_free_space(ctl, info);
2408                         WARN_ON(ret);
2409                         if (ret)
2410                                 goto out_lock;
2411
2412                         /* Not enough bytes in this entry to satisfy us */
2413                         if (old_end < offset + bytes) {
2414                                 bytes -= old_end - offset;
2415                                 offset = old_end;
2416                                 goto again;
2417                         } else if (old_end == offset + bytes) {
2418                                 /* all done */
2419                                 goto out_lock;
2420                         }
2421                         spin_unlock(&ctl->tree_lock);
2422
2423                         ret = btrfs_add_free_space(block_group, offset + bytes,
2424                                                    old_end - (offset + bytes));
2425                         WARN_ON(ret);
2426                         goto out;
2427                 }
2428         }
2429
2430         ret = remove_from_bitmap(ctl, info, &offset, &bytes);
2431         if (ret == -EAGAIN) {
2432                 re_search = true;
2433                 goto again;
2434         }
2435 out_lock:
2436         spin_unlock(&ctl->tree_lock);
2437 out:
2438         return ret;
2439 }
2440
2441 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
2442                            u64 bytes)
2443 {
2444         struct btrfs_fs_info *fs_info = block_group->fs_info;
2445         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2446         struct btrfs_free_space *info;
2447         struct rb_node *n;
2448         int count = 0;
2449
2450         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
2451                 info = rb_entry(n, struct btrfs_free_space, offset_index);
2452                 if (info->bytes >= bytes && !block_group->ro)
2453                         count++;
2454                 btrfs_crit(fs_info, "entry offset %llu, bytes %llu, bitmap %s",
2455                            info->offset, info->bytes,
2456                        (info->bitmap) ? "yes" : "no");
2457         }
2458         btrfs_info(fs_info, "block group has cluster?: %s",
2459                list_empty(&block_group->cluster_list) ? "no" : "yes");
2460         btrfs_info(fs_info,
2461                    "%d blocks of free space at or bigger than bytes is", count);
2462 }
2463
2464 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
2465 {
2466         struct btrfs_fs_info *fs_info = block_group->fs_info;
2467         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2468
2469         spin_lock_init(&ctl->tree_lock);
2470         ctl->unit = fs_info->sectorsize;
2471         ctl->start = block_group->key.objectid;
2472         ctl->private = block_group;
2473         ctl->op = &free_space_op;
2474         INIT_LIST_HEAD(&ctl->trimming_ranges);
2475         mutex_init(&ctl->cache_writeout_mutex);
2476
2477         /*
2478          * we only want to have 32k of ram per block group for keeping
2479          * track of free space, and if we pass 1/2 of that we want to
2480          * start converting things over to using bitmaps
2481          */
2482         ctl->extents_thresh = (SZ_32K / 2) / sizeof(struct btrfs_free_space);
2483 }
2484
2485 /*
2486  * for a given cluster, put all of its extents back into the free
2487  * space cache.  If the block group passed doesn't match the block group
2488  * pointed to by the cluster, someone else raced in and freed the
2489  * cluster already.  In that case, we just return without changing anything
2490  */
2491 static int
2492 __btrfs_return_cluster_to_free_space(
2493                              struct btrfs_block_group_cache *block_group,
2494                              struct btrfs_free_cluster *cluster)
2495 {
2496         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2497         struct btrfs_free_space *entry;
2498         struct rb_node *node;
2499
2500         spin_lock(&cluster->lock);
2501         if (cluster->block_group != block_group)
2502                 goto out;
2503
2504         cluster->block_group = NULL;
2505         cluster->window_start = 0;
2506         list_del_init(&cluster->block_group_list);
2507
2508         node = rb_first(&cluster->root);
2509         while (node) {
2510                 bool bitmap;
2511
2512                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2513                 node = rb_next(&entry->offset_index);
2514                 rb_erase(&entry->offset_index, &cluster->root);
2515                 RB_CLEAR_NODE(&entry->offset_index);
2516
2517                 bitmap = (entry->bitmap != NULL);
2518                 if (!bitmap) {
2519                         try_merge_free_space(ctl, entry, false);
2520                         steal_from_bitmap(ctl, entry, false);
2521                 }
2522                 tree_insert_offset(&ctl->free_space_offset,
2523                                    entry->offset, &entry->offset_index, bitmap);
2524         }
2525         cluster->root = RB_ROOT;
2526
2527 out:
2528         spin_unlock(&cluster->lock);
2529         btrfs_put_block_group(block_group);
2530         return 0;
2531 }
2532
2533 static void __btrfs_remove_free_space_cache_locked(
2534                                 struct btrfs_free_space_ctl *ctl)
2535 {
2536         struct btrfs_free_space *info;
2537         struct rb_node *node;
2538
2539         while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
2540                 info = rb_entry(node, struct btrfs_free_space, offset_index);
2541                 if (!info->bitmap) {
2542                         unlink_free_space(ctl, info);
2543                         kmem_cache_free(btrfs_free_space_cachep, info);
2544                 } else {
2545                         free_bitmap(ctl, info);
2546                 }
2547
2548                 cond_resched_lock(&ctl->tree_lock);
2549         }
2550 }
2551
2552 void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
2553 {
2554         spin_lock(&ctl->tree_lock);
2555         __btrfs_remove_free_space_cache_locked(ctl);
2556         spin_unlock(&ctl->tree_lock);
2557 }
2558
2559 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
2560 {
2561         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2562         struct btrfs_free_cluster *cluster;
2563         struct list_head *head;
2564
2565         spin_lock(&ctl->tree_lock);
2566         while ((head = block_group->cluster_list.next) !=
2567                &block_group->cluster_list) {
2568                 cluster = list_entry(head, struct btrfs_free_cluster,
2569                                      block_group_list);
2570
2571                 WARN_ON(cluster->block_group != block_group);
2572                 __btrfs_return_cluster_to_free_space(block_group, cluster);
2573
2574                 cond_resched_lock(&ctl->tree_lock);
2575         }
2576         __btrfs_remove_free_space_cache_locked(ctl);
2577         spin_unlock(&ctl->tree_lock);
2578
2579 }
2580
2581 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
2582                                u64 offset, u64 bytes, u64 empty_size,
2583                                u64 *max_extent_size)
2584 {
2585         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2586         struct btrfs_free_space *entry = NULL;
2587         u64 bytes_search = bytes + empty_size;
2588         u64 ret = 0;
2589         u64 align_gap = 0;
2590         u64 align_gap_len = 0;
2591
2592         spin_lock(&ctl->tree_lock);
2593         entry = find_free_space(ctl, &offset, &bytes_search,
2594                                 block_group->full_stripe_len, max_extent_size);
2595         if (!entry)
2596                 goto out;
2597
2598         ret = offset;
2599         if (entry->bitmap) {
2600                 bitmap_clear_bits(ctl, entry, offset, bytes);
2601                 if (!entry->bytes)
2602                         free_bitmap(ctl, entry);
2603         } else {
2604                 unlink_free_space(ctl, entry);
2605                 align_gap_len = offset - entry->offset;
2606                 align_gap = entry->offset;
2607
2608                 entry->offset = offset + bytes;
2609                 WARN_ON(entry->bytes < bytes + align_gap_len);
2610
2611                 entry->bytes -= bytes + align_gap_len;
2612                 if (!entry->bytes)
2613                         kmem_cache_free(btrfs_free_space_cachep, entry);
2614                 else
2615                         link_free_space(ctl, entry);
2616         }
2617 out:
2618         spin_unlock(&ctl->tree_lock);
2619
2620         if (align_gap_len)
2621                 __btrfs_add_free_space(block_group->fs_info, ctl,
2622                                        align_gap, align_gap_len);
2623         return ret;
2624 }
2625
2626 /*
2627  * given a cluster, put all of its extents back into the free space
2628  * cache.  If a block group is passed, this function will only free
2629  * a cluster that belongs to the passed block group.
2630  *
2631  * Otherwise, it'll get a reference on the block group pointed to by the
2632  * cluster and remove the cluster from it.
2633  */
2634 int btrfs_return_cluster_to_free_space(
2635                                struct btrfs_block_group_cache *block_group,
2636                                struct btrfs_free_cluster *cluster)
2637 {
2638         struct btrfs_free_space_ctl *ctl;
2639         int ret;
2640
2641         /* first, get a safe pointer to the block group */
2642         spin_lock(&cluster->lock);
2643         if (!block_group) {
2644                 block_group = cluster->block_group;
2645                 if (!block_group) {
2646                         spin_unlock(&cluster->lock);
2647                         return 0;
2648                 }
2649         } else if (cluster->block_group != block_group) {
2650                 /* someone else has already freed it don't redo their work */
2651                 spin_unlock(&cluster->lock);
2652                 return 0;
2653         }
2654         atomic_inc(&block_group->count);
2655         spin_unlock(&cluster->lock);
2656
2657         ctl = block_group->free_space_ctl;
2658
2659         /* now return any extents the cluster had on it */
2660         spin_lock(&ctl->tree_lock);
2661         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
2662         spin_unlock(&ctl->tree_lock);
2663
2664         /* finally drop our ref */
2665         btrfs_put_block_group(block_group);
2666         return ret;
2667 }
2668
2669 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
2670                                    struct btrfs_free_cluster *cluster,
2671                                    struct btrfs_free_space *entry,
2672                                    u64 bytes, u64 min_start,
2673                                    u64 *max_extent_size)
2674 {
2675         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2676         int err;
2677         u64 search_start = cluster->window_start;
2678         u64 search_bytes = bytes;
2679         u64 ret = 0;
2680
2681         search_start = min_start;
2682         search_bytes = bytes;
2683
2684         err = search_bitmap(ctl, entry, &search_start, &search_bytes, true);
2685         if (err) {
2686                 if (search_bytes > *max_extent_size)
2687                         *max_extent_size = search_bytes;
2688                 return 0;
2689         }
2690
2691         ret = search_start;
2692         __bitmap_clear_bits(ctl, entry, ret, bytes);
2693
2694         return ret;
2695 }
2696
2697 /*
2698  * given a cluster, try to allocate 'bytes' from it, returns 0
2699  * if it couldn't find anything suitably large, or a logical disk offset
2700  * if things worked out
2701  */
2702 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
2703                              struct btrfs_free_cluster *cluster, u64 bytes,
2704                              u64 min_start, u64 *max_extent_size)
2705 {
2706         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2707         struct btrfs_free_space *entry = NULL;
2708         struct rb_node *node;
2709         u64 ret = 0;
2710
2711         spin_lock(&cluster->lock);
2712         if (bytes > cluster->max_size)
2713                 goto out;
2714
2715         if (cluster->block_group != block_group)
2716                 goto out;
2717
2718         node = rb_first(&cluster->root);
2719         if (!node)
2720                 goto out;
2721
2722         entry = rb_entry(node, struct btrfs_free_space, offset_index);
2723         while (1) {
2724                 if (entry->bytes < bytes && entry->bytes > *max_extent_size)
2725                         *max_extent_size = entry->bytes;
2726
2727                 if (entry->bytes < bytes ||
2728                     (!entry->bitmap && entry->offset < min_start)) {
2729                         node = rb_next(&entry->offset_index);
2730                         if (!node)
2731                                 break;
2732                         entry = rb_entry(node, struct btrfs_free_space,
2733                                          offset_index);
2734                         continue;
2735                 }
2736
2737                 if (entry->bitmap) {
2738                         ret = btrfs_alloc_from_bitmap(block_group,
2739                                                       cluster, entry, bytes,
2740                                                       cluster->window_start,
2741                                                       max_extent_size);
2742                         if (ret == 0) {
2743                                 node = rb_next(&entry->offset_index);
2744                                 if (!node)
2745                                         break;
2746                                 entry = rb_entry(node, struct btrfs_free_space,
2747                                                  offset_index);
2748                                 continue;
2749                         }
2750                         cluster->window_start += bytes;
2751                 } else {
2752                         ret = entry->offset;
2753
2754                         entry->offset += bytes;
2755                         entry->bytes -= bytes;
2756                 }
2757
2758                 if (entry->bytes == 0)
2759                         rb_erase(&entry->offset_index, &cluster->root);
2760                 break;
2761         }
2762 out:
2763         spin_unlock(&cluster->lock);
2764
2765         if (!ret)
2766                 return 0;
2767
2768         spin_lock(&ctl->tree_lock);
2769
2770         ctl->free_space -= bytes;
2771         if (entry->bytes == 0) {
2772                 ctl->free_extents--;
2773                 if (entry->bitmap) {
2774                         kfree(entry->bitmap);
2775                         ctl->total_bitmaps--;
2776                         ctl->op->recalc_thresholds(ctl);
2777                 }
2778                 kmem_cache_free(btrfs_free_space_cachep, entry);
2779         }
2780
2781         spin_unlock(&ctl->tree_lock);
2782
2783         return ret;
2784 }
2785
2786 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2787                                 struct btrfs_free_space *entry,
2788                                 struct btrfs_free_cluster *cluster,
2789                                 u64 offset, u64 bytes,
2790                                 u64 cont1_bytes, u64 min_bytes)
2791 {
2792         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2793         unsigned long next_zero;
2794         unsigned long i;
2795         unsigned long want_bits;
2796         unsigned long min_bits;
2797         unsigned long found_bits;
2798         unsigned long max_bits = 0;
2799         unsigned long start = 0;
2800         unsigned long total_found = 0;
2801         int ret;
2802
2803         i = offset_to_bit(entry->offset, ctl->unit,
2804                           max_t(u64, offset, entry->offset));
2805         want_bits = bytes_to_bits(bytes, ctl->unit);
2806         min_bits = bytes_to_bits(min_bytes, ctl->unit);
2807
2808         /*
2809          * Don't bother looking for a cluster in this bitmap if it's heavily
2810          * fragmented.
2811          */
2812         if (entry->max_extent_size &&
2813             entry->max_extent_size < cont1_bytes)
2814                 return -ENOSPC;
2815 again:
2816         found_bits = 0;
2817         for_each_set_bit_from(i, entry->bitmap, BITS_PER_BITMAP) {
2818                 next_zero = find_next_zero_bit(entry->bitmap,
2819                                                BITS_PER_BITMAP, i);
2820                 if (next_zero - i >= min_bits) {
2821                         found_bits = next_zero - i;
2822                         if (found_bits > max_bits)
2823                                 max_bits = found_bits;
2824                         break;
2825                 }
2826                 if (next_zero - i > max_bits)
2827                         max_bits = next_zero - i;
2828                 i = next_zero;
2829         }
2830
2831         if (!found_bits) {
2832                 entry->max_extent_size = (u64)max_bits * ctl->unit;
2833                 return -ENOSPC;
2834         }
2835
2836         if (!total_found) {
2837                 start = i;
2838                 cluster->max_size = 0;
2839         }
2840
2841         total_found += found_bits;
2842
2843         if (cluster->max_size < found_bits * ctl->unit)
2844                 cluster->max_size = found_bits * ctl->unit;
2845
2846         if (total_found < want_bits || cluster->max_size < cont1_bytes) {
2847                 i = next_zero + 1;
2848                 goto again;
2849         }
2850
2851         cluster->window_start = start * ctl->unit + entry->offset;
2852         rb_erase(&entry->offset_index, &ctl->free_space_offset);
2853         ret = tree_insert_offset(&cluster->root, entry->offset,
2854                                  &entry->offset_index, 1);
2855         ASSERT(!ret); /* -EEXIST; Logic error */
2856
2857         trace_btrfs_setup_cluster(block_group, cluster,
2858                                   total_found * ctl->unit, 1);
2859         return 0;
2860 }
2861
2862 /*
2863  * This searches the block group for just extents to fill the cluster with.
2864  * Try to find a cluster with at least bytes total bytes, at least one
2865  * extent of cont1_bytes, and other clusters of at least min_bytes.
2866  */
2867 static noinline int
2868 setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2869                         struct btrfs_free_cluster *cluster,
2870                         struct list_head *bitmaps, u64 offset, u64 bytes,
2871                         u64 cont1_bytes, u64 min_bytes)
2872 {
2873         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2874         struct btrfs_free_space *first = NULL;
2875         struct btrfs_free_space *entry = NULL;
2876         struct btrfs_free_space *last;
2877         struct rb_node *node;
2878         u64 window_free;
2879         u64 max_extent;
2880         u64 total_size = 0;
2881
2882         entry = tree_search_offset(ctl, offset, 0, 1);
2883         if (!entry)
2884                 return -ENOSPC;
2885
2886         /*
2887          * We don't want bitmaps, so just move along until we find a normal
2888          * extent entry.
2889          */
2890         while (entry->bitmap || entry->bytes < min_bytes) {
2891                 if (entry->bitmap && list_empty(&entry->list))
2892                         list_add_tail(&entry->list, bitmaps);
2893                 node = rb_next(&entry->offset_index);
2894                 if (!node)
2895                         return -ENOSPC;
2896                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2897         }
2898
2899         window_free = entry->bytes;
2900         max_extent = entry->bytes;
2901         first = entry;
2902         last = entry;
2903
2904         for (node = rb_next(&entry->offset_index); node;
2905              node = rb_next(&entry->offset_index)) {
2906                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2907
2908                 if (entry->bitmap) {
2909                         if (list_empty(&entry->list))
2910                                 list_add_tail(&entry->list, bitmaps);
2911                         continue;
2912                 }
2913
2914                 if (entry->bytes < min_bytes)
2915                         continue;
2916
2917                 last = entry;
2918                 window_free += entry->bytes;
2919                 if (entry->bytes > max_extent)
2920                         max_extent = entry->bytes;
2921         }
2922
2923         if (window_free < bytes || max_extent < cont1_bytes)
2924                 return -ENOSPC;
2925
2926         cluster->window_start = first->offset;
2927
2928         node = &first->offset_index;
2929
2930         /*
2931          * now we've found our entries, pull them out of the free space
2932          * cache and put them into the cluster rbtree
2933          */
2934         do {
2935                 int ret;
2936
2937                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2938                 node = rb_next(&entry->offset_index);
2939                 if (entry->bitmap || entry->bytes < min_bytes)
2940                         continue;
2941
2942                 rb_erase(&entry->offset_index, &ctl->free_space_offset);
2943                 ret = tree_insert_offset(&cluster->root, entry->offset,
2944                                          &entry->offset_index, 0);
2945                 total_size += entry->bytes;
2946                 ASSERT(!ret); /* -EEXIST; Logic error */
2947         } while (node && entry != last);
2948
2949         cluster->max_size = max_extent;
2950         trace_btrfs_setup_cluster(block_group, cluster, total_size, 0);
2951         return 0;
2952 }
2953
2954 /*
2955  * This specifically looks for bitmaps that may work in the cluster, we assume
2956  * that we have already failed to find extents that will work.
2957  */
2958 static noinline int
2959 setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2960                      struct btrfs_free_cluster *cluster,
2961                      struct list_head *bitmaps, u64 offset, u64 bytes,
2962                      u64 cont1_bytes, u64 min_bytes)
2963 {
2964         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2965         struct btrfs_free_space *entry = NULL;
2966         int ret = -ENOSPC;
2967         u64 bitmap_offset = offset_to_bitmap(ctl, offset);
2968
2969         if (ctl->total_bitmaps == 0)
2970                 return -ENOSPC;
2971
2972         /*
2973          * The bitmap that covers offset won't be in the list unless offset
2974          * is just its start offset.
2975          */
2976         if (!list_empty(bitmaps))
2977                 entry = list_first_entry(bitmaps, struct btrfs_free_space, list);
2978
2979         if (!entry || entry->offset != bitmap_offset) {
2980                 entry = tree_search_offset(ctl, bitmap_offset, 1, 0);
2981                 if (entry && list_empty(&entry->list))
2982                         list_add(&entry->list, bitmaps);
2983         }
2984
2985         list_for_each_entry(entry, bitmaps, list) {
2986                 if (entry->bytes < bytes)
2987                         continue;
2988                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2989                                            bytes, cont1_bytes, min_bytes);
2990                 if (!ret)
2991                         return 0;
2992         }
2993
2994         /*
2995          * The bitmaps list has all the bitmaps that record free space
2996          * starting after offset, so no more search is required.
2997          */
2998         return -ENOSPC;
2999 }
3000
3001 /*
3002  * here we try to find a cluster of blocks in a block group.  The goal
3003  * is to find at least bytes+empty_size.
3004  * We might not find them all in one contiguous area.
3005  *
3006  * returns zero and sets up cluster if things worked out, otherwise
3007  * it returns -enospc
3008  */
3009 int btrfs_find_space_cluster(struct btrfs_fs_info *fs_info,
3010                              struct btrfs_block_group_cache *block_group,
3011                              struct btrfs_free_cluster *cluster,
3012                              u64 offset, u64 bytes, u64 empty_size)
3013 {
3014         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
3015         struct btrfs_free_space *entry, *tmp;
3016         LIST_HEAD(bitmaps);
3017         u64 min_bytes;
3018         u64 cont1_bytes;
3019         int ret;
3020
3021         /*
3022          * Choose the minimum extent size we'll require for this
3023          * cluster.  For SSD_SPREAD, don't allow any fragmentation.
3024          * For metadata, allow allocates with smaller extents.  For
3025          * data, keep it dense.
3026          */
3027         if (btrfs_test_opt(fs_info, SSD_SPREAD)) {
3028                 cont1_bytes = min_bytes = bytes + empty_size;
3029         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
3030                 cont1_bytes = bytes;
3031                 min_bytes = fs_info->sectorsize;
3032         } else {
3033                 cont1_bytes = max(bytes, (bytes + empty_size) >> 2);
3034                 min_bytes = fs_info->sectorsize;
3035         }
3036
3037         spin_lock(&ctl->tree_lock);
3038
3039         /*
3040          * If we know we don't have enough space to make a cluster don't even
3041          * bother doing all the work to try and find one.
3042          */
3043         if (ctl->free_space < bytes) {
3044                 spin_unlock(&ctl->tree_lock);
3045                 return -ENOSPC;
3046         }
3047
3048         spin_lock(&cluster->lock);
3049
3050         /* someone already found a cluster, hooray */
3051         if (cluster->block_group) {
3052                 ret = 0;
3053                 goto out;
3054         }
3055
3056         trace_btrfs_find_cluster(block_group, offset, bytes, empty_size,
3057                                  min_bytes);
3058
3059         ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
3060                                       bytes + empty_size,
3061                                       cont1_bytes, min_bytes);
3062         if (ret)
3063                 ret = setup_cluster_bitmap(block_group, cluster, &bitmaps,
3064                                            offset, bytes + empty_size,
3065                                            cont1_bytes, min_bytes);
3066
3067         /* Clear our temporary list */
3068         list_for_each_entry_safe(entry, tmp, &bitmaps, list)
3069                 list_del_init(&entry->list);
3070
3071         if (!ret) {
3072                 atomic_inc(&block_group->count);
3073                 list_add_tail(&cluster->block_group_list,
3074                               &block_group->cluster_list);
3075                 cluster->block_group = block_group;
3076         } else {
3077                 trace_btrfs_failed_cluster_setup(block_group);
3078         }
3079 out:
3080         spin_unlock(&cluster->lock);
3081         spin_unlock(&ctl->tree_lock);
3082
3083         return ret;
3084 }
3085
3086 /*
3087  * simple code to zero out a cluster
3088  */
3089 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
3090 {
3091         spin_lock_init(&cluster->lock);
3092         spin_lock_init(&cluster->refill_lock);
3093         cluster->root = RB_ROOT;
3094         cluster->max_size = 0;
3095         cluster->fragmented = false;
3096         INIT_LIST_HEAD(&cluster->block_group_list);
3097         cluster->block_group = NULL;
3098 }
3099
3100 static int do_trimming(struct btrfs_block_group_cache *block_group,
3101                        u64 *total_trimmed, u64 start, u64 bytes,
3102                        u64 reserved_start, u64 reserved_bytes,
3103                        struct btrfs_trim_range *trim_entry)
3104 {
3105         struct btrfs_space_info *space_info = block_group->space_info;
3106         struct btrfs_fs_info *fs_info = block_group->fs_info;
3107         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
3108         int ret;
3109         int update = 0;
3110         u64 trimmed = 0;
3111
3112         spin_lock(&space_info->lock);
3113         spin_lock(&block_group->lock);
3114         if (!block_group->ro) {
3115                 block_group->reserved += reserved_bytes;
3116                 space_info->bytes_reserved += reserved_bytes;
3117                 update = 1;
3118         }
3119         spin_unlock(&block_group->lock);
3120         spin_unlock(&space_info->lock);
3121
3122         ret = btrfs_discard_extent(fs_info, start, bytes, &trimmed);
3123         if (!ret)
3124                 *total_trimmed += trimmed;
3125
3126         mutex_lock(&ctl->cache_writeout_mutex);
3127         btrfs_add_free_space(block_group, reserved_start, reserved_bytes);
3128         list_del(&trim_entry->list);
3129         mutex_unlock(&ctl->cache_writeout_mutex);
3130
3131         if (update) {
3132                 spin_lock(&space_info->lock);