1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2015 Facebook. All rights reserved.
4 */
5
6 #include <linux/kernel.h>
7 #include <linux/sched/mm.h>
8 #include "messages.h"
9 #include "ctree.h"
10 #include "disk-io.h"
11 #include "locking.h"
12 #include "free-space-tree.h"
13 #include "transaction.h"
14 #include "block-group.h"
15 #include "fs.h"
16 #include "accessors.h"
17 #include "extent-tree.h"
18 #include "root-tree.h"
19
20 static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
21 struct btrfs_block_group *block_group,
22 struct btrfs_path *path);
23
btrfs_free_space_root(struct btrfs_block_group * block_group)24 static struct btrfs_root *btrfs_free_space_root(
25 struct btrfs_block_group *block_group)
26 {
27 struct btrfs_key key = {
28 .objectid = BTRFS_FREE_SPACE_TREE_OBJECTID,
29 .type = BTRFS_ROOT_ITEM_KEY,
30 .offset = 0,
31 };
32
33 if (btrfs_fs_incompat(block_group->fs_info, EXTENT_TREE_V2))
34 key.offset = block_group->global_root_id;
35 return btrfs_global_root(block_group->fs_info, &key);
36 }
37
set_free_space_tree_thresholds(struct btrfs_block_group * cache)38 void set_free_space_tree_thresholds(struct btrfs_block_group *cache)
39 {
40 u32 bitmap_range;
41 size_t bitmap_size;
42 u64 num_bitmaps, total_bitmap_size;
43
44 if (WARN_ON(cache->length == 0))
45 btrfs_warn(cache->fs_info, "block group %llu length is zero",
46 cache->start);
47
48 /*
49 * We convert to bitmaps when the disk space required for using extents
50 * exceeds that required for using bitmaps.
51 */
52 bitmap_range = cache->fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
53 num_bitmaps = div_u64(cache->length + bitmap_range - 1, bitmap_range);
54 bitmap_size = sizeof(struct btrfs_item) + BTRFS_FREE_SPACE_BITMAP_SIZE;
55 total_bitmap_size = num_bitmaps * bitmap_size;
56 cache->bitmap_high_thresh = div_u64(total_bitmap_size,
57 sizeof(struct btrfs_item));
58
59 /*
60 * We allow for a small buffer between the high threshold and low
61 * threshold to avoid thrashing back and forth between the two formats.
62 */
63 if (cache->bitmap_high_thresh > 100)
64 cache->bitmap_low_thresh = cache->bitmap_high_thresh - 100;
65 else
66 cache->bitmap_low_thresh = 0;
67 }
68
add_new_free_space_info(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path)69 static int add_new_free_space_info(struct btrfs_trans_handle *trans,
70 struct btrfs_block_group *block_group,
71 struct btrfs_path *path)
72 {
73 struct btrfs_root *root = btrfs_free_space_root(block_group);
74 struct btrfs_free_space_info *info;
75 struct btrfs_key key;
76 struct extent_buffer *leaf;
77 int ret;
78
79 key.objectid = block_group->start;
80 key.type = BTRFS_FREE_SPACE_INFO_KEY;
81 key.offset = block_group->length;
82
83 ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*info));
84 if (ret)
85 goto out;
86
87 leaf = path->nodes[0];
88 info = btrfs_item_ptr(leaf, path->slots[0],
89 struct btrfs_free_space_info);
90 btrfs_set_free_space_extent_count(leaf, info, 0);
91 btrfs_set_free_space_flags(leaf, info, 0);
92 btrfs_mark_buffer_dirty(trans, leaf);
93
94 ret = 0;
95 out:
96 btrfs_release_path(path);
97 return ret;
98 }
99
100 EXPORT_FOR_TESTS
search_free_space_info(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path,int cow)101 struct btrfs_free_space_info *search_free_space_info(
102 struct btrfs_trans_handle *trans,
103 struct btrfs_block_group *block_group,
104 struct btrfs_path *path, int cow)
105 {
106 struct btrfs_fs_info *fs_info = block_group->fs_info;
107 struct btrfs_root *root = btrfs_free_space_root(block_group);
108 struct btrfs_key key;
109 int ret;
110
111 key.objectid = block_group->start;
112 key.type = BTRFS_FREE_SPACE_INFO_KEY;
113 key.offset = block_group->length;
114
115 ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
116 if (ret < 0)
117 return ERR_PTR(ret);
118 if (ret != 0) {
119 btrfs_warn(fs_info, "missing free space info for %llu",
120 block_group->start);
121 ASSERT(0);
122 return ERR_PTR(-ENOENT);
123 }
124
125 return btrfs_item_ptr(path->nodes[0], path->slots[0],
126 struct btrfs_free_space_info);
127 }
128
129 /*
130 * btrfs_search_slot() but we're looking for the greatest key less than the
131 * passed key.
132 */
btrfs_search_prev_slot(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_key * key,struct btrfs_path * p,int ins_len,int cow)133 static int btrfs_search_prev_slot(struct btrfs_trans_handle *trans,
134 struct btrfs_root *root,
135 struct btrfs_key *key, struct btrfs_path *p,
136 int ins_len, int cow)
137 {
138 int ret;
139
140 ret = btrfs_search_slot(trans, root, key, p, ins_len, cow);
141 if (ret < 0)
142 return ret;
143
144 if (ret == 0) {
145 ASSERT(0);
146 return -EIO;
147 }
148
149 if (p->slots[0] == 0) {
150 ASSERT(0);
151 return -EIO;
152 }
153 p->slots[0]--;
154
155 return 0;
156 }
157
free_space_bitmap_size(const struct btrfs_fs_info * fs_info,u64 size)158 static inline u32 free_space_bitmap_size(const struct btrfs_fs_info *fs_info,
159 u64 size)
160 {
161 return DIV_ROUND_UP(size >> fs_info->sectorsize_bits, BITS_PER_BYTE);
162 }
163
alloc_bitmap(u32 bitmap_size)164 static unsigned long *alloc_bitmap(u32 bitmap_size)
165 {
166 unsigned long *ret;
167 unsigned int nofs_flag;
168 u32 bitmap_rounded_size = round_up(bitmap_size, sizeof(unsigned long));
169
170 /*
171 * GFP_NOFS doesn't work with kvmalloc(), but we really can't recurse
172 * into the filesystem as the free space bitmap can be modified in the
173 * critical section of a transaction commit.
174 *
175 * TODO: push the memalloc_nofs_{save,restore}() to the caller where we
176 * know that recursion is unsafe.
177 */
178 nofs_flag = memalloc_nofs_save();
179 ret = kvzalloc(bitmap_rounded_size, GFP_KERNEL);
180 memalloc_nofs_restore(nofs_flag);
181 return ret;
182 }
183
le_bitmap_set(unsigned long * map,unsigned int start,int len)184 static void le_bitmap_set(unsigned long *map, unsigned int start, int len)
185 {
186 u8 *p = ((u8 *)map) + BIT_BYTE(start);
187 const unsigned int size = start + len;
188 int bits_to_set = BITS_PER_BYTE - (start % BITS_PER_BYTE);
189 u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(start);
190
191 while (len - bits_to_set >= 0) {
192 *p |= mask_to_set;
193 len -= bits_to_set;
194 bits_to_set = BITS_PER_BYTE;
195 mask_to_set = ~0;
196 p++;
197 }
198 if (len) {
199 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
200 *p |= mask_to_set;
201 }
202 }
203
204 EXPORT_FOR_TESTS
convert_free_space_to_bitmaps(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path)205 int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
206 struct btrfs_block_group *block_group,
207 struct btrfs_path *path)
208 {
209 struct btrfs_fs_info *fs_info = trans->fs_info;
210 struct btrfs_root *root = btrfs_free_space_root(block_group);
211 struct btrfs_free_space_info *info;
212 struct btrfs_key key, found_key;
213 struct extent_buffer *leaf;
214 unsigned long *bitmap;
215 char *bitmap_cursor;
216 u64 start, end;
217 u64 bitmap_range, i;
218 u32 bitmap_size, flags, expected_extent_count;
219 u32 extent_count = 0;
220 int done = 0, nr;
221 int ret;
222
223 bitmap_size = free_space_bitmap_size(fs_info, block_group->length);
224 bitmap = alloc_bitmap(bitmap_size);
225 if (!bitmap) {
226 ret = -ENOMEM;
227 goto out;
228 }
229
230 start = block_group->start;
231 end = block_group->start + block_group->length;
232
233 key.objectid = end - 1;
234 key.type = (u8)-1;
235 key.offset = (u64)-1;
236
237 while (!done) {
238 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
239 if (ret)
240 goto out;
241
242 leaf = path->nodes[0];
243 nr = 0;
244 path->slots[0]++;
245 while (path->slots[0] > 0) {
246 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
247
248 if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
249 ASSERT(found_key.objectid == block_group->start);
250 ASSERT(found_key.offset == block_group->length);
251 done = 1;
252 break;
253 } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY) {
254 u64 first, last;
255
256 ASSERT(found_key.objectid >= start);
257 ASSERT(found_key.objectid < end);
258 ASSERT(found_key.objectid + found_key.offset <= end);
259
260 first = div_u64(found_key.objectid - start,
261 fs_info->sectorsize);
262 last = div_u64(found_key.objectid + found_key.offset - start,
263 fs_info->sectorsize);
264 le_bitmap_set(bitmap, first, last - first);
265
266 extent_count++;
267 nr++;
268 path->slots[0]--;
269 } else {
270 ASSERT(0);
271 }
272 }
273
274 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
275 if (ret)
276 goto out;
277 btrfs_release_path(path);
278 }
279
280 info = search_free_space_info(trans, block_group, path, 1);
281 if (IS_ERR(info)) {
282 ret = PTR_ERR(info);
283 goto out;
284 }
285 leaf = path->nodes[0];
286 flags = btrfs_free_space_flags(leaf, info);
287 flags |= BTRFS_FREE_SPACE_USING_BITMAPS;
288 btrfs_set_free_space_flags(leaf, info, flags);
289 expected_extent_count = btrfs_free_space_extent_count(leaf, info);
290 btrfs_mark_buffer_dirty(trans, leaf);
291 btrfs_release_path(path);
292
293 if (extent_count != expected_extent_count) {
294 btrfs_err(fs_info,
295 "incorrect extent count for %llu; counted %u, expected %u",
296 block_group->start, extent_count,
297 expected_extent_count);
298 ASSERT(0);
299 ret = -EIO;
300 goto out;
301 }
302
303 bitmap_cursor = (char *)bitmap;
304 bitmap_range = fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
305 i = start;
306 while (i < end) {
307 unsigned long ptr;
308 u64 extent_size;
309 u32 data_size;
310
311 extent_size = min(end - i, bitmap_range);
312 data_size = free_space_bitmap_size(fs_info, extent_size);
313
314 key.objectid = i;
315 key.type = BTRFS_FREE_SPACE_BITMAP_KEY;
316 key.offset = extent_size;
317
318 ret = btrfs_insert_empty_item(trans, root, path, &key,
319 data_size);
320 if (ret)
321 goto out;
322
323 leaf = path->nodes[0];
324 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
325 write_extent_buffer(leaf, bitmap_cursor, ptr,
326 data_size);
327 btrfs_mark_buffer_dirty(trans, leaf);
328 btrfs_release_path(path);
329
330 i += extent_size;
331 bitmap_cursor += data_size;
332 }
333
334 ret = 0;
335 out:
336 kvfree(bitmap);
337 if (ret)
338 btrfs_abort_transaction(trans, ret);
339 return ret;
340 }
341
342 EXPORT_FOR_TESTS
convert_free_space_to_extents(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path)343 int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
344 struct btrfs_block_group *block_group,
345 struct btrfs_path *path)
346 {
347 struct btrfs_fs_info *fs_info = trans->fs_info;
348 struct btrfs_root *root = btrfs_free_space_root(block_group);
349 struct btrfs_free_space_info *info;
350 struct btrfs_key key, found_key;
351 struct extent_buffer *leaf;
352 unsigned long *bitmap;
353 u64 start, end;
354 u32 bitmap_size, flags, expected_extent_count;
355 unsigned long nrbits, start_bit, end_bit;
356 u32 extent_count = 0;
357 int done = 0, nr;
358 int ret;
359
360 bitmap_size = free_space_bitmap_size(fs_info, block_group->length);
361 bitmap = alloc_bitmap(bitmap_size);
362 if (!bitmap) {
363 ret = -ENOMEM;
364 goto out;
365 }
366
367 start = block_group->start;
368 end = block_group->start + block_group->length;
369
370 key.objectid = end - 1;
371 key.type = (u8)-1;
372 key.offset = (u64)-1;
373
374 while (!done) {
375 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
376 if (ret)
377 goto out;
378
379 leaf = path->nodes[0];
380 nr = 0;
381 path->slots[0]++;
382 while (path->slots[0] > 0) {
383 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
384
385 if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
386 ASSERT(found_key.objectid == block_group->start);
387 ASSERT(found_key.offset == block_group->length);
388 done = 1;
389 break;
390 } else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
391 unsigned long ptr;
392 char *bitmap_cursor;
393 u32 bitmap_pos, data_size;
394
395 ASSERT(found_key.objectid >= start);
396 ASSERT(found_key.objectid < end);
397 ASSERT(found_key.objectid + found_key.offset <= end);
398
399 bitmap_pos = div_u64(found_key.objectid - start,
400 fs_info->sectorsize *
401 BITS_PER_BYTE);
402 bitmap_cursor = ((char *)bitmap) + bitmap_pos;
403 data_size = free_space_bitmap_size(fs_info,
404 found_key.offset);
405
406 ptr = btrfs_item_ptr_offset(leaf, path->slots[0] - 1);
407 read_extent_buffer(leaf, bitmap_cursor, ptr,
408 data_size);
409
410 nr++;
411 path->slots[0]--;
412 } else {
413 ASSERT(0);
414 }
415 }
416
417 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
418 if (ret)
419 goto out;
420 btrfs_release_path(path);
421 }
422
423 info = search_free_space_info(trans, block_group, path, 1);
424 if (IS_ERR(info)) {
425 ret = PTR_ERR(info);
426 goto out;
427 }
428 leaf = path->nodes[0];
429 flags = btrfs_free_space_flags(leaf, info);
430 flags &= ~BTRFS_FREE_SPACE_USING_BITMAPS;
431 btrfs_set_free_space_flags(leaf, info, flags);
432 expected_extent_count = btrfs_free_space_extent_count(leaf, info);
433 btrfs_mark_buffer_dirty(trans, leaf);
434 btrfs_release_path(path);
435
436 nrbits = block_group->length >> block_group->fs_info->sectorsize_bits;
437 start_bit = find_next_bit_le(bitmap, nrbits, 0);
438
439 while (start_bit < nrbits) {
440 end_bit = find_next_zero_bit_le(bitmap, nrbits, start_bit);
441 ASSERT(start_bit < end_bit);
442
443 key.objectid = start + start_bit * block_group->fs_info->sectorsize;
444 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
445 key.offset = (end_bit - start_bit) * block_group->fs_info->sectorsize;
446
447 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
448 if (ret)
449 goto out;
450 btrfs_release_path(path);
451
452 extent_count++;
453
454 start_bit = find_next_bit_le(bitmap, nrbits, end_bit);
455 }
456
457 if (extent_count != expected_extent_count) {
458 btrfs_err(fs_info,
459 "incorrect extent count for %llu; counted %u, expected %u",
460 block_group->start, extent_count,
461 expected_extent_count);
462 ASSERT(0);
463 ret = -EIO;
464 goto out;
465 }
466
467 ret = 0;
468 out:
469 kvfree(bitmap);
470 if (ret)
471 btrfs_abort_transaction(trans, ret);
472 return ret;
473 }
474
update_free_space_extent_count(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path,int new_extents)475 static int update_free_space_extent_count(struct btrfs_trans_handle *trans,
476 struct btrfs_block_group *block_group,
477 struct btrfs_path *path,
478 int new_extents)
479 {
480 struct btrfs_free_space_info *info;
481 u32 flags;
482 u32 extent_count;
483 int ret = 0;
484
485 if (new_extents == 0)
486 return 0;
487
488 info = search_free_space_info(trans, block_group, path, 1);
489 if (IS_ERR(info)) {
490 ret = PTR_ERR(info);
491 goto out;
492 }
493 flags = btrfs_free_space_flags(path->nodes[0], info);
494 extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
495
496 extent_count += new_extents;
497 btrfs_set_free_space_extent_count(path->nodes[0], info, extent_count);
498 btrfs_mark_buffer_dirty(trans, path->nodes[0]);
499 btrfs_release_path(path);
500
501 if (!(flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
502 extent_count > block_group->bitmap_high_thresh) {
503 ret = convert_free_space_to_bitmaps(trans, block_group, path);
504 } else if ((flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
505 extent_count < block_group->bitmap_low_thresh) {
506 ret = convert_free_space_to_extents(trans, block_group, path);
507 }
508
509 out:
510 return ret;
511 }
512
513 EXPORT_FOR_TESTS
free_space_test_bit(struct btrfs_block_group * block_group,struct btrfs_path * path,u64 offset)514 int free_space_test_bit(struct btrfs_block_group *block_group,
515 struct btrfs_path *path, u64 offset)
516 {
517 struct extent_buffer *leaf;
518 struct btrfs_key key;
519 u64 found_start, found_end;
520 unsigned long ptr, i;
521
522 leaf = path->nodes[0];
523 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
524 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
525
526 found_start = key.objectid;
527 found_end = key.objectid + key.offset;
528 ASSERT(offset >= found_start && offset < found_end);
529
530 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
531 i = div_u64(offset - found_start,
532 block_group->fs_info->sectorsize);
533 return !!extent_buffer_test_bit(leaf, ptr, i);
534 }
535
free_space_set_bits(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path,u64 * start,u64 * size,int bit)536 static void free_space_set_bits(struct btrfs_trans_handle *trans,
537 struct btrfs_block_group *block_group,
538 struct btrfs_path *path, u64 *start, u64 *size,
539 int bit)
540 {
541 struct btrfs_fs_info *fs_info = block_group->fs_info;
542 struct extent_buffer *leaf;
543 struct btrfs_key key;
544 u64 end = *start + *size;
545 u64 found_start, found_end;
546 unsigned long ptr, first, last;
547
548 leaf = path->nodes[0];
549 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
550 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
551
552 found_start = key.objectid;
553 found_end = key.objectid + key.offset;
554 ASSERT(*start >= found_start && *start < found_end);
555 ASSERT(end > found_start);
556
557 if (end > found_end)
558 end = found_end;
559
560 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
561 first = (*start - found_start) >> fs_info->sectorsize_bits;
562 last = (end - found_start) >> fs_info->sectorsize_bits;
563 if (bit)
564 extent_buffer_bitmap_set(leaf, ptr, first, last - first);
565 else
566 extent_buffer_bitmap_clear(leaf, ptr, first, last - first);
567 btrfs_mark_buffer_dirty(trans, leaf);
568
569 *size -= end - *start;
570 *start = end;
571 }
572
573 /*
574 * We can't use btrfs_next_item() in modify_free_space_bitmap() because
575 * btrfs_next_leaf() doesn't get the path for writing. We can forgo the fancy
576 * tree walking in btrfs_next_leaf() anyways because we know exactly what we're
577 * looking for.
578 */
free_space_next_bitmap(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * p)579 static int free_space_next_bitmap(struct btrfs_trans_handle *trans,
580 struct btrfs_root *root, struct btrfs_path *p)
581 {
582 struct btrfs_key key;
583
584 if (p->slots[0] + 1 < btrfs_header_nritems(p->nodes[0])) {
585 p->slots[0]++;
586 return 0;
587 }
588
589 btrfs_item_key_to_cpu(p->nodes[0], &key, p->slots[0]);
590 btrfs_release_path(p);
591
592 key.objectid += key.offset;
593 key.type = (u8)-1;
594 key.offset = (u64)-1;
595
596 return btrfs_search_prev_slot(trans, root, &key, p, 0, 1);
597 }
598
599 /*
600 * If remove is 1, then we are removing free space, thus clearing bits in the
601 * bitmap. If remove is 0, then we are adding free space, thus setting bits in
602 * the bitmap.
603 */
modify_free_space_bitmap(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path,u64 start,u64 size,int remove)604 static int modify_free_space_bitmap(struct btrfs_trans_handle *trans,
605 struct btrfs_block_group *block_group,
606 struct btrfs_path *path,
607 u64 start, u64 size, int remove)
608 {
609 struct btrfs_root *root = btrfs_free_space_root(block_group);
610 struct btrfs_key key;
611 u64 end = start + size;
612 u64 cur_start, cur_size;
613 int prev_bit, next_bit;
614 int new_extents;
615 int ret;
616
617 /*
618 * Read the bit for the block immediately before the extent of space if
619 * that block is within the block group.
620 */
621 if (start > block_group->start) {
622 u64 prev_block = start - block_group->fs_info->sectorsize;
623
624 key.objectid = prev_block;
625 key.type = (u8)-1;
626 key.offset = (u64)-1;
627
628 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
629 if (ret)
630 goto out;
631
632 prev_bit = free_space_test_bit(block_group, path, prev_block);
633
634 /* The previous block may have been in the previous bitmap. */
635 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
636 if (start >= key.objectid + key.offset) {
637 ret = free_space_next_bitmap(trans, root, path);
638 if (ret)
639 goto out;
640 }
641 } else {
642 key.objectid = start;
643 key.type = (u8)-1;
644 key.offset = (u64)-1;
645
646 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
647 if (ret)
648 goto out;
649
650 prev_bit = -1;
651 }
652
653 /*
654 * Iterate over all of the bitmaps overlapped by the extent of space,
655 * clearing/setting bits as required.
656 */
657 cur_start = start;
658 cur_size = size;
659 while (1) {
660 free_space_set_bits(trans, block_group, path, &cur_start, &cur_size,
661 !remove);
662 if (cur_size == 0)
663 break;
664 ret = free_space_next_bitmap(trans, root, path);
665 if (ret)
666 goto out;
667 }
668
669 /*
670 * Read the bit for the block immediately after the extent of space if
671 * that block is within the block group.
672 */
673 if (end < block_group->start + block_group->length) {
674 /* The next block may be in the next bitmap. */
675 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
676 if (end >= key.objectid + key.offset) {
677 ret = free_space_next_bitmap(trans, root, path);
678 if (ret)
679 goto out;
680 }
681
682 next_bit = free_space_test_bit(block_group, path, end);
683 } else {
684 next_bit = -1;
685 }
686
687 if (remove) {
688 new_extents = -1;
689 if (prev_bit == 1) {
690 /* Leftover on the left. */
691 new_extents++;
692 }
693 if (next_bit == 1) {
694 /* Leftover on the right. */
695 new_extents++;
696 }
697 } else {
698 new_extents = 1;
699 if (prev_bit == 1) {
700 /* Merging with neighbor on the left. */
701 new_extents--;
702 }
703 if (next_bit == 1) {
704 /* Merging with neighbor on the right. */
705 new_extents--;
706 }
707 }
708
709 btrfs_release_path(path);
710 ret = update_free_space_extent_count(trans, block_group, path,
711 new_extents);
712
713 out:
714 return ret;
715 }
716
remove_free_space_extent(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path,u64 start,u64 size)717 static int remove_free_space_extent(struct btrfs_trans_handle *trans,
718 struct btrfs_block_group *block_group,
719 struct btrfs_path *path,
720 u64 start, u64 size)
721 {
722 struct btrfs_root *root = btrfs_free_space_root(block_group);
723 struct btrfs_key key;
724 u64 found_start, found_end;
725 u64 end = start + size;
726 int new_extents = -1;
727 int ret;
728
729 key.objectid = start;
730 key.type = (u8)-1;
731 key.offset = (u64)-1;
732
733 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
734 if (ret)
735 goto out;
736
737 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
738
739 ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
740
741 found_start = key.objectid;
742 found_end = key.objectid + key.offset;
743 ASSERT(start >= found_start && end <= found_end);
744
745 /*
746 * Okay, now that we've found the free space extent which contains the
747 * free space that we are removing, there are four cases:
748 *
749 * 1. We're using the whole extent: delete the key we found and
750 * decrement the free space extent count.
751 * 2. We are using part of the extent starting at the beginning: delete
752 * the key we found and insert a new key representing the leftover at
753 * the end. There is no net change in the number of extents.
754 * 3. We are using part of the extent ending at the end: delete the key
755 * we found and insert a new key representing the leftover at the
756 * beginning. There is no net change in the number of extents.
757 * 4. We are using part of the extent in the middle: delete the key we
758 * found and insert two new keys representing the leftovers on each
759 * side. Where we used to have one extent, we now have two, so increment
760 * the extent count. We may need to convert the block group to bitmaps
761 * as a result.
762 */
763
764 /* Delete the existing key (cases 1-4). */
765 ret = btrfs_del_item(trans, root, path);
766 if (ret)
767 goto out;
768
769 /* Add a key for leftovers at the beginning (cases 3 and 4). */
770 if (start > found_start) {
771 key.objectid = found_start;
772 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
773 key.offset = start - found_start;
774
775 btrfs_release_path(path);
776 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
777 if (ret)
778 goto out;
779 new_extents++;
780 }
781
782 /* Add a key for leftovers at the end (cases 2 and 4). */
783 if (end < found_end) {
784 key.objectid = end;
785 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
786 key.offset = found_end - end;
787
788 btrfs_release_path(path);
789 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
790 if (ret)
791 goto out;
792 new_extents++;
793 }
794
795 btrfs_release_path(path);
796 ret = update_free_space_extent_count(trans, block_group, path,
797 new_extents);
798
799 out:
800 return ret;
801 }
802
803 EXPORT_FOR_TESTS
__remove_from_free_space_tree(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path,u64 start,u64 size)804 int __remove_from_free_space_tree(struct btrfs_trans_handle *trans,
805 struct btrfs_block_group *block_group,
806 struct btrfs_path *path, u64 start, u64 size)
807 {
808 struct btrfs_free_space_info *info;
809 u32 flags;
810 int ret;
811
812 if (test_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &block_group->runtime_flags)) {
813 ret = __add_block_group_free_space(trans, block_group, path);
814 if (ret)
815 return ret;
816 }
817
818 info = search_free_space_info(NULL, block_group, path, 0);
819 if (IS_ERR(info))
820 return PTR_ERR(info);
821 flags = btrfs_free_space_flags(path->nodes[0], info);
822 btrfs_release_path(path);
823
824 if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
825 return modify_free_space_bitmap(trans, block_group, path,
826 start, size, 1);
827 } else {
828 return remove_free_space_extent(trans, block_group, path,
829 start, size);
830 }
831 }
832
remove_from_free_space_tree(struct btrfs_trans_handle * trans,u64 start,u64 size)833 int remove_from_free_space_tree(struct btrfs_trans_handle *trans,
834 u64 start, u64 size)
835 {
836 struct btrfs_block_group *block_group;
837 struct btrfs_path *path;
838 int ret;
839
840 if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
841 return 0;
842
843 path = btrfs_alloc_path();
844 if (!path) {
845 ret = -ENOMEM;
846 goto out;
847 }
848
849 block_group = btrfs_lookup_block_group(trans->fs_info, start);
850 if (!block_group) {
851 ASSERT(0);
852 ret = -ENOENT;
853 goto out;
854 }
855
856 mutex_lock(&block_group->free_space_lock);
857 ret = __remove_from_free_space_tree(trans, block_group, path, start,
858 size);
859 mutex_unlock(&block_group->free_space_lock);
860
861 btrfs_put_block_group(block_group);
862 out:
863 btrfs_free_path(path);
864 if (ret)
865 btrfs_abort_transaction(trans, ret);
866 return ret;
867 }
868
add_free_space_extent(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path,u64 start,u64 size)869 static int add_free_space_extent(struct btrfs_trans_handle *trans,
870 struct btrfs_block_group *block_group,
871 struct btrfs_path *path,
872 u64 start, u64 size)
873 {
874 struct btrfs_root *root = btrfs_free_space_root(block_group);
875 struct btrfs_key key, new_key;
876 u64 found_start, found_end;
877 u64 end = start + size;
878 int new_extents = 1;
879 int ret;
880
881 /*
882 * We are adding a new extent of free space, but we need to merge
883 * extents. There are four cases here:
884 *
885 * 1. The new extent does not have any immediate neighbors to merge
886 * with: add the new key and increment the free space extent count. We
887 * may need to convert the block group to bitmaps as a result.
888 * 2. The new extent has an immediate neighbor before it: remove the
889 * previous key and insert a new key combining both of them. There is no
890 * net change in the number of extents.
891 * 3. The new extent has an immediate neighbor after it: remove the next
892 * key and insert a new key combining both of them. There is no net
893 * change in the number of extents.
894 * 4. The new extent has immediate neighbors on both sides: remove both
895 * of the keys and insert a new key combining all of them. Where we used
896 * to have two extents, we now have one, so decrement the extent count.
897 */
898
899 new_key.objectid = start;
900 new_key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
901 new_key.offset = size;
902
903 /* Search for a neighbor on the left. */
904 if (start == block_group->start)
905 goto right;
906 key.objectid = start - 1;
907 key.type = (u8)-1;
908 key.offset = (u64)-1;
909
910 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
911 if (ret)
912 goto out;
913
914 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
915
916 if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
917 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
918 btrfs_release_path(path);
919 goto right;
920 }
921
922 found_start = key.objectid;
923 found_end = key.objectid + key.offset;
924 ASSERT(found_start >= block_group->start &&
925 found_end > block_group->start);
926 ASSERT(found_start < start && found_end <= start);
927
928 /*
929 * Delete the neighbor on the left and absorb it into the new key (cases
930 * 2 and 4).
931 */
932 if (found_end == start) {
933 ret = btrfs_del_item(trans, root, path);
934 if (ret)
935 goto out;
936 new_key.objectid = found_start;
937 new_key.offset += key.offset;
938 new_extents--;
939 }
940 btrfs_release_path(path);
941
942 right:
943 /* Search for a neighbor on the right. */
944 if (end == block_group->start + block_group->length)
945 goto insert;
946 key.objectid = end;
947 key.type = (u8)-1;
948 key.offset = (u64)-1;
949
950 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
951 if (ret)
952 goto out;
953
954 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
955
956 if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
957 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
958 btrfs_release_path(path);
959 goto insert;
960 }
961
962 found_start = key.objectid;
963 found_end = key.objectid + key.offset;
964 ASSERT(found_start >= block_group->start &&
965 found_end > block_group->start);
966 ASSERT((found_start < start && found_end <= start) ||
967 (found_start >= end && found_end > end));
968
969 /*
970 * Delete the neighbor on the right and absorb it into the new key
971 * (cases 3 and 4).
972 */
973 if (found_start == end) {
974 ret = btrfs_del_item(trans, root, path);
975 if (ret)
976 goto out;
977 new_key.offset += key.offset;
978 new_extents--;
979 }
980 btrfs_release_path(path);
981
982 insert:
983 /* Insert the new key (cases 1-4). */
984 ret = btrfs_insert_empty_item(trans, root, path, &new_key, 0);
985 if (ret)
986 goto out;
987
988 btrfs_release_path(path);
989 ret = update_free_space_extent_count(trans, block_group, path,
990 new_extents);
991
992 out:
993 return ret;
994 }
995
996 EXPORT_FOR_TESTS
__add_to_free_space_tree(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path,u64 start,u64 size)997 int __add_to_free_space_tree(struct btrfs_trans_handle *trans,
998 struct btrfs_block_group *block_group,
999 struct btrfs_path *path, u64 start, u64 size)
1000 {
1001 struct btrfs_free_space_info *info;
1002 u32 flags;
1003 int ret;
1004
1005 if (test_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &block_group->runtime_flags)) {
1006 ret = __add_block_group_free_space(trans, block_group, path);
1007 if (ret)
1008 return ret;
1009 }
1010
1011 info = search_free_space_info(NULL, block_group, path, 0);
1012 if (IS_ERR(info))
1013 return PTR_ERR(info);
1014 flags = btrfs_free_space_flags(path->nodes[0], info);
1015 btrfs_release_path(path);
1016
1017 if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
1018 return modify_free_space_bitmap(trans, block_group, path,
1019 start, size, 0);
1020 } else {
1021 return add_free_space_extent(trans, block_group, path, start,
1022 size);
1023 }
1024 }
1025
add_to_free_space_tree(struct btrfs_trans_handle * trans,u64 start,u64 size)1026 int add_to_free_space_tree(struct btrfs_trans_handle *trans,
1027 u64 start, u64 size)
1028 {
1029 struct btrfs_block_group *block_group;
1030 struct btrfs_path *path;
1031 int ret;
1032
1033 if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1034 return 0;
1035
1036 path = btrfs_alloc_path();
1037 if (!path) {
1038 ret = -ENOMEM;
1039 goto out;
1040 }
1041
1042 block_group = btrfs_lookup_block_group(trans->fs_info, start);
1043 if (!block_group) {
1044 ASSERT(0);
1045 ret = -ENOENT;
1046 goto out;
1047 }
1048
1049 mutex_lock(&block_group->free_space_lock);
1050 ret = __add_to_free_space_tree(trans, block_group, path, start, size);
1051 mutex_unlock(&block_group->free_space_lock);
1052
1053 btrfs_put_block_group(block_group);
1054 out:
1055 btrfs_free_path(path);
1056 if (ret)
1057 btrfs_abort_transaction(trans, ret);
1058 return ret;
1059 }
1060
1061 /*
1062 * Populate the free space tree by walking the extent tree. Operations on the
1063 * extent tree that happen as a result of writes to the free space tree will go
1064 * through the normal add/remove hooks.
1065 */
populate_free_space_tree(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group)1066 static int populate_free_space_tree(struct btrfs_trans_handle *trans,
1067 struct btrfs_block_group *block_group)
1068 {
1069 struct btrfs_root *extent_root;
1070 struct btrfs_path *path, *path2;
1071 struct btrfs_key key;
1072 u64 start, end;
1073 int ret;
1074
1075 path = btrfs_alloc_path();
1076 if (!path)
1077 return -ENOMEM;
1078 path->reada = READA_FORWARD;
1079
1080 path2 = btrfs_alloc_path();
1081 if (!path2) {
1082 btrfs_free_path(path);
1083 return -ENOMEM;
1084 }
1085
1086 ret = add_new_free_space_info(trans, block_group, path2);
1087 if (ret)
1088 goto out;
1089
1090 mutex_lock(&block_group->free_space_lock);
1091
1092 /*
1093 * Iterate through all of the extent and metadata items in this block
1094 * group, adding the free space between them and the free space at the
1095 * end. Note that EXTENT_ITEM and METADATA_ITEM are less than
1096 * BLOCK_GROUP_ITEM, so an extent may precede the block group that it's
1097 * contained in.
1098 */
1099 key.objectid = block_group->start;
1100 key.type = BTRFS_EXTENT_ITEM_KEY;
1101 key.offset = 0;
1102
1103 extent_root = btrfs_extent_root(trans->fs_info, key.objectid);
1104 ret = btrfs_search_slot_for_read(extent_root, &key, path, 1, 0);
1105 if (ret < 0)
1106 goto out_locked;
1107 /*
1108 * If ret is 1 (no key found), it means this is an empty block group,
1109 * without any extents allocated from it and there's no block group
1110 * item (key BTRFS_BLOCK_GROUP_ITEM_KEY) located in the extent tree
1111 * because we are using the block group tree feature, so block group
1112 * items are stored in the block group tree. It also means there are no
1113 * extents allocated for block groups with a start offset beyond this
1114 * block group's end offset (this is the last, highest, block group).
1115 */
1116 if (!btrfs_fs_compat_ro(trans->fs_info, BLOCK_GROUP_TREE))
1117 ASSERT(ret == 0);
1118
1119 start = block_group->start;
1120 end = block_group->start + block_group->length;
1121 while (ret == 0) {
1122 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1123
1124 if (key.type == BTRFS_EXTENT_ITEM_KEY ||
1125 key.type == BTRFS_METADATA_ITEM_KEY) {
1126 if (key.objectid >= end)
1127 break;
1128
1129 if (start < key.objectid) {
1130 ret = __add_to_free_space_tree(trans,
1131 block_group,
1132 path2, start,
1133 key.objectid -
1134 start);
1135 if (ret)
1136 goto out_locked;
1137 }
1138 start = key.objectid;
1139 if (key.type == BTRFS_METADATA_ITEM_KEY)
1140 start += trans->fs_info->nodesize;
1141 else
1142 start += key.offset;
1143 } else if (key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
1144 if (key.objectid != block_group->start)
1145 break;
1146 }
1147
1148 ret = btrfs_next_item(extent_root, path);
1149 if (ret < 0)
1150 goto out_locked;
1151 }
1152 if (start < end) {
1153 ret = __add_to_free_space_tree(trans, block_group, path2,
1154 start, end - start);
1155 if (ret)
1156 goto out_locked;
1157 }
1158
1159 ret = 0;
1160 out_locked:
1161 mutex_unlock(&block_group->free_space_lock);
1162 out:
1163 btrfs_free_path(path2);
1164 btrfs_free_path(path);
1165 return ret;
1166 }
1167
btrfs_create_free_space_tree(struct btrfs_fs_info * fs_info)1168 int btrfs_create_free_space_tree(struct btrfs_fs_info *fs_info)
1169 {
1170 struct btrfs_trans_handle *trans;
1171 struct btrfs_root *tree_root = fs_info->tree_root;
1172 struct btrfs_root *free_space_root;
1173 struct btrfs_block_group *block_group;
1174 struct rb_node *node;
1175 int ret;
1176
1177 trans = btrfs_start_transaction(tree_root, 0);
1178 if (IS_ERR(trans))
1179 return PTR_ERR(trans);
1180
1181 set_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1182 set_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1183 free_space_root = btrfs_create_tree(trans,
1184 BTRFS_FREE_SPACE_TREE_OBJECTID);
1185 if (IS_ERR(free_space_root)) {
1186 ret = PTR_ERR(free_space_root);
1187 btrfs_abort_transaction(trans, ret);
1188 btrfs_end_transaction(trans);
1189 goto out_clear;
1190 }
1191 ret = btrfs_global_root_insert(free_space_root);
1192 if (ret) {
1193 btrfs_put_root(free_space_root);
1194 btrfs_abort_transaction(trans, ret);
1195 btrfs_end_transaction(trans);
1196 goto out_clear;
1197 }
1198
1199 node = rb_first_cached(&fs_info->block_group_cache_tree);
1200 while (node) {
1201 block_group = rb_entry(node, struct btrfs_block_group,
1202 cache_node);
1203 ret = populate_free_space_tree(trans, block_group);
1204 if (ret) {
1205 btrfs_abort_transaction(trans, ret);
1206 btrfs_end_transaction(trans);
1207 goto out_clear;
1208 }
1209 node = rb_next(node);
1210 }
1211
1212 btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1213 btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1214 clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1215 ret = btrfs_commit_transaction(trans);
1216
1217 /*
1218 * Now that we've committed the transaction any reading of our commit
1219 * root will be safe, so we can cache from the free space tree now.
1220 */
1221 clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1222 return ret;
1223
1224 out_clear:
1225 clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1226 clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1227 return ret;
1228 }
1229
clear_free_space_tree(struct btrfs_trans_handle * trans,struct btrfs_root * root)1230 static int clear_free_space_tree(struct btrfs_trans_handle *trans,
1231 struct btrfs_root *root)
1232 {
1233 struct btrfs_path *path;
1234 struct btrfs_key key;
1235 int nr;
1236 int ret;
1237
1238 path = btrfs_alloc_path();
1239 if (!path)
1240 return -ENOMEM;
1241
1242 key.objectid = 0;
1243 key.type = 0;
1244 key.offset = 0;
1245
1246 while (1) {
1247 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1248 if (ret < 0)
1249 goto out;
1250
1251 nr = btrfs_header_nritems(path->nodes[0]);
1252 if (!nr)
1253 break;
1254
1255 path->slots[0] = 0;
1256 ret = btrfs_del_items(trans, root, path, 0, nr);
1257 if (ret)
1258 goto out;
1259
1260 btrfs_release_path(path);
1261 }
1262
1263 ret = 0;
1264 out:
1265 btrfs_free_path(path);
1266 return ret;
1267 }
1268
btrfs_delete_free_space_tree(struct btrfs_fs_info * fs_info)1269 int btrfs_delete_free_space_tree(struct btrfs_fs_info *fs_info)
1270 {
1271 struct btrfs_trans_handle *trans;
1272 struct btrfs_root *tree_root = fs_info->tree_root;
1273 struct btrfs_key key = {
1274 .objectid = BTRFS_FREE_SPACE_TREE_OBJECTID,
1275 .type = BTRFS_ROOT_ITEM_KEY,
1276 .offset = 0,
1277 };
1278 struct btrfs_root *free_space_root = btrfs_global_root(fs_info, &key);
1279 int ret;
1280
1281 trans = btrfs_start_transaction(tree_root, 0);
1282 if (IS_ERR(trans))
1283 return PTR_ERR(trans);
1284
1285 btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1286 btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1287
1288 ret = clear_free_space_tree(trans, free_space_root);
1289 if (ret) {
1290 btrfs_abort_transaction(trans, ret);
1291 btrfs_end_transaction(trans);
1292 return ret;
1293 }
1294
1295 ret = btrfs_del_root(trans, &free_space_root->root_key);
1296 if (ret) {
1297 btrfs_abort_transaction(trans, ret);
1298 btrfs_end_transaction(trans);
1299 return ret;
1300 }
1301
1302 btrfs_global_root_delete(free_space_root);
1303
1304 spin_lock(&fs_info->trans_lock);
1305 list_del(&free_space_root->dirty_list);
1306 spin_unlock(&fs_info->trans_lock);
1307
1308 btrfs_tree_lock(free_space_root->node);
1309 btrfs_clear_buffer_dirty(trans, free_space_root->node);
1310 btrfs_tree_unlock(free_space_root->node);
1311 ret = btrfs_free_tree_block(trans, btrfs_root_id(free_space_root),
1312 free_space_root->node, 0, 1);
1313 btrfs_put_root(free_space_root);
1314 if (ret < 0) {
1315 btrfs_abort_transaction(trans, ret);
1316 btrfs_end_transaction(trans);
1317 return ret;
1318 }
1319
1320 return btrfs_commit_transaction(trans);
1321 }
1322
btrfs_rebuild_free_space_tree(struct btrfs_fs_info * fs_info)1323 int btrfs_rebuild_free_space_tree(struct btrfs_fs_info *fs_info)
1324 {
1325 struct btrfs_trans_handle *trans;
1326 struct btrfs_key key = {
1327 .objectid = BTRFS_FREE_SPACE_TREE_OBJECTID,
1328 .type = BTRFS_ROOT_ITEM_KEY,
1329 .offset = 0,
1330 };
1331 struct btrfs_root *free_space_root = btrfs_global_root(fs_info, &key);
1332 struct rb_node *node;
1333 int ret;
1334
1335 trans = btrfs_start_transaction(free_space_root, 1);
1336 if (IS_ERR(trans))
1337 return PTR_ERR(trans);
1338
1339 set_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1340 set_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1341
1342 ret = clear_free_space_tree(trans, free_space_root);
1343 if (ret) {
1344 btrfs_abort_transaction(trans, ret);
1345 btrfs_end_transaction(trans);
1346 return ret;
1347 }
1348
1349 node = rb_first_cached(&fs_info->block_group_cache_tree);
1350 while (node) {
1351 struct btrfs_block_group *block_group;
1352
1353 block_group = rb_entry(node, struct btrfs_block_group,
1354 cache_node);
1355 ret = populate_free_space_tree(trans, block_group);
1356 if (ret) {
1357 btrfs_abort_transaction(trans, ret);
1358 btrfs_end_transaction(trans);
1359 return ret;
1360 }
1361 node = rb_next(node);
1362 }
1363
1364 btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1365 btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1366 clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1367
1368 ret = btrfs_commit_transaction(trans);
1369 clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1370 return ret;
1371 }
1372
__add_block_group_free_space(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group,struct btrfs_path * path)1373 static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
1374 struct btrfs_block_group *block_group,
1375 struct btrfs_path *path)
1376 {
1377 int ret;
1378
1379 clear_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &block_group->runtime_flags);
1380
1381 ret = add_new_free_space_info(trans, block_group, path);
1382 if (ret) {
1383 btrfs_abort_transaction(trans, ret);
1384 return ret;
1385 }
1386
1387 ret = __add_to_free_space_tree(trans, block_group, path,
1388 block_group->start, block_group->length);
1389 if (ret)
1390 btrfs_abort_transaction(trans, ret);
1391
1392 return 0;
1393 }
1394
add_block_group_free_space(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group)1395 int add_block_group_free_space(struct btrfs_trans_handle *trans,
1396 struct btrfs_block_group *block_group)
1397 {
1398 struct btrfs_fs_info *fs_info = trans->fs_info;
1399 struct btrfs_path *path = NULL;
1400 int ret = 0;
1401
1402 if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
1403 return 0;
1404
1405 mutex_lock(&block_group->free_space_lock);
1406 if (!test_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &block_group->runtime_flags))
1407 goto out;
1408
1409 path = btrfs_alloc_path();
1410 if (!path) {
1411 ret = -ENOMEM;
1412 btrfs_abort_transaction(trans, ret);
1413 goto out;
1414 }
1415
1416 ret = __add_block_group_free_space(trans, block_group, path);
1417 out:
1418 btrfs_free_path(path);
1419 mutex_unlock(&block_group->free_space_lock);
1420 return ret;
1421 }
1422
remove_block_group_free_space(struct btrfs_trans_handle * trans,struct btrfs_block_group * block_group)1423 int remove_block_group_free_space(struct btrfs_trans_handle *trans,
1424 struct btrfs_block_group *block_group)
1425 {
1426 struct btrfs_root *root = btrfs_free_space_root(block_group);
1427 struct btrfs_path *path;
1428 struct btrfs_key key, found_key;
1429 struct extent_buffer *leaf;
1430 u64 start, end;
1431 int done = 0, nr;
1432 int ret;
1433
1434 if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1435 return 0;
1436
1437 if (test_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &block_group->runtime_flags)) {
1438 /* We never added this block group to the free space tree. */
1439 return 0;
1440 }
1441
1442 path = btrfs_alloc_path();
1443 if (!path) {
1444 ret = -ENOMEM;
1445 goto out;
1446 }
1447
1448 start = block_group->start;
1449 end = block_group->start + block_group->length;
1450
1451 key.objectid = end - 1;
1452 key.type = (u8)-1;
1453 key.offset = (u64)-1;
1454
1455 while (!done) {
1456 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
1457 if (ret)
1458 goto out;
1459
1460 leaf = path->nodes[0];
1461 nr = 0;
1462 path->slots[0]++;
1463 while (path->slots[0] > 0) {
1464 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
1465
1466 if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
1467 ASSERT(found_key.objectid == block_group->start);
1468 ASSERT(found_key.offset == block_group->length);
1469 done = 1;
1470 nr++;
1471 path->slots[0]--;
1472 break;
1473 } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY ||
1474 found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
1475 ASSERT(found_key.objectid >= start);
1476 ASSERT(found_key.objectid < end);
1477 ASSERT(found_key.objectid + found_key.offset <= end);
1478 nr++;
1479 path->slots[0]--;
1480 } else {
1481 ASSERT(0);
1482 }
1483 }
1484
1485 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
1486 if (ret)
1487 goto out;
1488 btrfs_release_path(path);
1489 }
1490
1491 ret = 0;
1492 out:
1493 btrfs_free_path(path);
1494 if (ret)
1495 btrfs_abort_transaction(trans, ret);
1496 return ret;
1497 }
1498
load_free_space_bitmaps(struct btrfs_caching_control * caching_ctl,struct btrfs_path * path,u32 expected_extent_count)1499 static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
1500 struct btrfs_path *path,
1501 u32 expected_extent_count)
1502 {
1503 struct btrfs_block_group *block_group;
1504 struct btrfs_fs_info *fs_info;
1505 struct btrfs_root *root;
1506 struct btrfs_key key;
1507 int prev_bit = 0, bit;
1508 /* Initialize to silence GCC. */
1509 u64 extent_start = 0;
1510 u64 end, offset;
1511 u64 total_found = 0;
1512 u32 extent_count = 0;
1513 int ret;
1514
1515 block_group = caching_ctl->block_group;
1516 fs_info = block_group->fs_info;
1517 root = btrfs_free_space_root(block_group);
1518
1519 end = block_group->start + block_group->length;
1520
1521 while (1) {
1522 ret = btrfs_next_item(root, path);
1523 if (ret < 0)
1524 goto out;
1525 if (ret)
1526 break;
1527
1528 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1529
1530 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1531 break;
1532
1533 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
1534 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1535
1536 offset = key.objectid;
1537 while (offset < key.objectid + key.offset) {
1538 bit = free_space_test_bit(block_group, path, offset);
1539 if (prev_bit == 0 && bit == 1) {
1540 extent_start = offset;
1541 } else if (prev_bit == 1 && bit == 0) {
1542 u64 space_added;
1543
1544 ret = btrfs_add_new_free_space(block_group,
1545 extent_start,
1546 offset,
1547 &space_added);
1548 if (ret)
1549 goto out;
1550 total_found += space_added;
1551 if (total_found > CACHING_CTL_WAKE_UP) {
1552 total_found = 0;
1553 wake_up(&caching_ctl->wait);
1554 }
1555 extent_count++;
1556 }
1557 prev_bit = bit;
1558 offset += fs_info->sectorsize;
1559 }
1560 }
1561 if (prev_bit == 1) {
1562 ret = btrfs_add_new_free_space(block_group, extent_start, end, NULL);
1563 if (ret)
1564 goto out;
1565 extent_count++;
1566 }
1567
1568 if (extent_count != expected_extent_count) {
1569 btrfs_err(fs_info,
1570 "incorrect extent count for %llu; counted %u, expected %u",
1571 block_group->start, extent_count,
1572 expected_extent_count);
1573 ASSERT(0);
1574 ret = -EIO;
1575 goto out;
1576 }
1577
1578 ret = 0;
1579 out:
1580 return ret;
1581 }
1582
load_free_space_extents(struct btrfs_caching_control * caching_ctl,struct btrfs_path * path,u32 expected_extent_count)1583 static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
1584 struct btrfs_path *path,
1585 u32 expected_extent_count)
1586 {
1587 struct btrfs_block_group *block_group;
1588 struct btrfs_fs_info *fs_info;
1589 struct btrfs_root *root;
1590 struct btrfs_key key;
1591 u64 end;
1592 u64 total_found = 0;
1593 u32 extent_count = 0;
1594 int ret;
1595
1596 block_group = caching_ctl->block_group;
1597 fs_info = block_group->fs_info;
1598 root = btrfs_free_space_root(block_group);
1599
1600 end = block_group->start + block_group->length;
1601
1602 while (1) {
1603 u64 space_added;
1604
1605 ret = btrfs_next_item(root, path);
1606 if (ret < 0)
1607 goto out;
1608 if (ret)
1609 break;
1610
1611 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1612
1613 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1614 break;
1615
1616 ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
1617 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1618
1619 ret = btrfs_add_new_free_space(block_group, key.objectid,
1620 key.objectid + key.offset,
1621 &space_added);
1622 if (ret)
1623 goto out;
1624 total_found += space_added;
1625 if (total_found > CACHING_CTL_WAKE_UP) {
1626 total_found = 0;
1627 wake_up(&caching_ctl->wait);
1628 }
1629 extent_count++;
1630 }
1631
1632 if (extent_count != expected_extent_count) {
1633 btrfs_err(fs_info,
1634 "incorrect extent count for %llu; counted %u, expected %u",
1635 block_group->start, extent_count,
1636 expected_extent_count);
1637 ASSERT(0);
1638 ret = -EIO;
1639 goto out;
1640 }
1641
1642 ret = 0;
1643 out:
1644 return ret;
1645 }
1646
load_free_space_tree(struct btrfs_caching_control * caching_ctl)1647 int load_free_space_tree(struct btrfs_caching_control *caching_ctl)
1648 {
1649 struct btrfs_block_group *block_group;
1650 struct btrfs_free_space_info *info;
1651 struct btrfs_path *path;
1652 u32 extent_count, flags;
1653 int ret;
1654
1655 block_group = caching_ctl->block_group;
1656
1657 path = btrfs_alloc_path();
1658 if (!path)
1659 return -ENOMEM;
1660
1661 /*
1662 * Just like caching_thread() doesn't want to deadlock on the extent
1663 * tree, we don't want to deadlock on the free space tree.
1664 */
1665 path->skip_locking = 1;
1666 path->search_commit_root = 1;
1667 path->reada = READA_FORWARD;
1668
1669 info = search_free_space_info(NULL, block_group, path, 0);
1670 if (IS_ERR(info)) {
1671 ret = PTR_ERR(info);
1672 goto out;
1673 }
1674 extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
1675 flags = btrfs_free_space_flags(path->nodes[0], info);
1676
1677 /*
1678 * We left path pointing to the free space info item, so now
1679 * load_free_space_foo can just iterate through the free space tree from
1680 * there.
1681 */
1682 if (flags & BTRFS_FREE_SPACE_USING_BITMAPS)
1683 ret = load_free_space_bitmaps(caching_ctl, path, extent_count);
1684 else
1685 ret = load_free_space_extents(caching_ctl, path, extent_count);
1686
1687 out:
1688 btrfs_free_path(path);
1689 return ret;
1690 }
1691