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TOMOYO Linux Cross Reference
Linux/fs/btrfs/free-space-cache.c

Version: ~ [ linux-5.4-rc7 ] ~ [ linux-5.3.11 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.84 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.154 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.201 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.201 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.77 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 /*
  2  * Copyright (C) 2008 Red Hat.  All rights reserved.
  3  *
  4  * This program is free software; you can redistribute it and/or
  5  * modify it under the terms of the GNU General Public
  6  * License v2 as published by the Free Software Foundation.
  7  *
  8  * This program is distributed in the hope that it will be useful,
  9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 11  * General Public License for more details.
 12  *
 13  * You should have received a copy of the GNU General Public
 14  * License along with this program; if not, write to the
 15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 16  * Boston, MA 021110-1307, USA.
 17  */
 18 
 19 #include <linux/pagemap.h>
 20 #include <linux/sched.h>
 21 #include <linux/slab.h>
 22 #include <linux/math64.h>
 23 #include <linux/ratelimit.h>
 24 #include "ctree.h"
 25 #include "free-space-cache.h"
 26 #include "transaction.h"
 27 #include "disk-io.h"
 28 #include "extent_io.h"
 29 #include "inode-map.h"
 30 
 31 #define BITS_PER_BITMAP         (PAGE_CACHE_SIZE * 8)
 32 #define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
 33 
 34 static int link_free_space(struct btrfs_free_space_ctl *ctl,
 35                            struct btrfs_free_space *info);
 36 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
 37                               struct btrfs_free_space *info);
 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_key key;
 44         struct btrfs_key location;
 45         struct btrfs_disk_key disk_key;
 46         struct btrfs_free_space_header *header;
 47         struct extent_buffer *leaf;
 48         struct inode *inode = NULL;
 49         int ret;
 50 
 51         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 52         key.offset = offset;
 53         key.type = 0;
 54 
 55         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 56         if (ret < 0)
 57                 return ERR_PTR(ret);
 58         if (ret > 0) {
 59                 btrfs_release_path(path);
 60                 return ERR_PTR(-ENOENT);
 61         }
 62 
 63         leaf = path->nodes[0];
 64         header = btrfs_item_ptr(leaf, path->slots[0],
 65                                 struct btrfs_free_space_header);
 66         btrfs_free_space_key(leaf, header, &disk_key);
 67         btrfs_disk_key_to_cpu(&location, &disk_key);
 68         btrfs_release_path(path);
 69 
 70         inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
 71         if (!inode)
 72                 return ERR_PTR(-ENOENT);
 73         if (IS_ERR(inode))
 74                 return inode;
 75         if (is_bad_inode(inode)) {
 76                 iput(inode);
 77                 return ERR_PTR(-ENOENT);
 78         }
 79 
 80         mapping_set_gfp_mask(inode->i_mapping,
 81                         mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);
 82 
 83         return inode;
 84 }
 85 
 86 struct inode *lookup_free_space_inode(struct btrfs_root *root,
 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(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                 printk(KERN_INFO "Old style space inode found, converting.\n");
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 int __create_free_space_inode(struct btrfs_root *root,
123                               struct btrfs_trans_handle *trans,
124                               struct btrfs_path *path, u64 ino, u64 offset)
125 {
126         struct btrfs_key key;
127         struct btrfs_disk_key disk_key;
128         struct btrfs_free_space_header *header;
129         struct btrfs_inode_item *inode_item;
130         struct extent_buffer *leaf;
131         u64 flags = BTRFS_INODE_NOCOMPRESS | BTRFS_INODE_PREALLOC;
132         int ret;
133 
134         ret = btrfs_insert_empty_inode(trans, root, path, ino);
135         if (ret)
136                 return ret;
137 
138         /* We inline crc's for the free disk space cache */
139         if (ino != BTRFS_FREE_INO_OBJECTID)
140                 flags |= BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
141 
142         leaf = path->nodes[0];
143         inode_item = btrfs_item_ptr(leaf, path->slots[0],
144                                     struct btrfs_inode_item);
145         btrfs_item_key(leaf, &disk_key, path->slots[0]);
146         memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
147                              sizeof(*inode_item));
148         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
149         btrfs_set_inode_size(leaf, inode_item, 0);
150         btrfs_set_inode_nbytes(leaf, inode_item, 0);
151         btrfs_set_inode_uid(leaf, inode_item, 0);
152         btrfs_set_inode_gid(leaf, inode_item, 0);
153         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
154         btrfs_set_inode_flags(leaf, inode_item, flags);
155         btrfs_set_inode_nlink(leaf, inode_item, 1);
156         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
157         btrfs_set_inode_block_group(leaf, inode_item, offset);
158         btrfs_mark_buffer_dirty(leaf);
159         btrfs_release_path(path);
160 
161         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
162         key.offset = offset;
163         key.type = 0;
164 
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         leaf = path->nodes[0];
172         header = btrfs_item_ptr(leaf, path->slots[0],
173                                 struct btrfs_free_space_header);
174         memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
175         btrfs_set_free_space_key(leaf, header, &disk_key);
176         btrfs_mark_buffer_dirty(leaf);
177         btrfs_release_path(path);
178 
179         return 0;
180 }
181 
182 int create_free_space_inode(struct btrfs_root *root,
183                             struct btrfs_trans_handle *trans,
184                             struct btrfs_block_group_cache *block_group,
185                             struct btrfs_path *path)
186 {
187         int ret;
188         u64 ino;
189 
190         ret = btrfs_find_free_objectid(root, &ino);
191         if (ret < 0)
192                 return ret;
193 
194         return __create_free_space_inode(root, trans, path, ino,
195                                          block_group->key.objectid);
196 }
197 
198 int btrfs_truncate_free_space_cache(struct btrfs_root *root,
199                                     struct btrfs_trans_handle *trans,
200                                     struct btrfs_path *path,
201                                     struct inode *inode)
202 {
203         struct btrfs_block_rsv *rsv;
204         u64 needed_bytes;
205         loff_t oldsize;
206         int ret = 0;
207 
208         rsv = trans->block_rsv;
209         trans->block_rsv = &root->fs_info->global_block_rsv;
210 
211         /* 1 for slack space, 1 for updating the inode */
212         needed_bytes = btrfs_calc_trunc_metadata_size(root, 1) +
213                 btrfs_calc_trans_metadata_size(root, 1);
214 
215         spin_lock(&trans->block_rsv->lock);
216         if (trans->block_rsv->reserved < needed_bytes) {
217                 spin_unlock(&trans->block_rsv->lock);
218                 trans->block_rsv = rsv;
219                 return -ENOSPC;
220         }
221         spin_unlock(&trans->block_rsv->lock);
222 
223         oldsize = i_size_read(inode);
224         btrfs_i_size_write(inode, 0);
225         truncate_pagecache(inode, oldsize, 0);
226 
227         /*
228          * We don't need an orphan item because truncating the free space cache
229          * will never be split across transactions.
230          */
231         ret = btrfs_truncate_inode_items(trans, root, inode,
232                                          0, BTRFS_EXTENT_DATA_KEY);
233 
234         if (ret) {
235                 trans->block_rsv = rsv;
236                 btrfs_abort_transaction(trans, root, ret);
237                 return ret;
238         }
239 
240         ret = btrfs_update_inode(trans, root, inode);
241         if (ret)
242                 btrfs_abort_transaction(trans, root, ret);
243         trans->block_rsv = rsv;
244 
245         return ret;
246 }
247 
248 static int readahead_cache(struct inode *inode)
249 {
250         struct file_ra_state *ra;
251         unsigned long last_index;
252 
253         ra = kzalloc(sizeof(*ra), GFP_NOFS);
254         if (!ra)
255                 return -ENOMEM;
256 
257         file_ra_state_init(ra, inode->i_mapping);
258         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
259 
260         page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
261 
262         kfree(ra);
263 
264         return 0;
265 }
266 
267 struct io_ctl {
268         void *cur, *orig;
269         struct page *page;
270         struct page **pages;
271         struct btrfs_root *root;
272         unsigned long size;
273         int index;
274         int num_pages;
275         unsigned check_crcs:1;
276 };
277 
278 static int io_ctl_init(struct io_ctl *io_ctl, struct inode *inode,
279                        struct btrfs_root *root)
280 {
281         memset(io_ctl, 0, sizeof(struct io_ctl));
282         io_ctl->num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
283                 PAGE_CACHE_SHIFT;
284         io_ctl->pages = kzalloc(sizeof(struct page *) * io_ctl->num_pages,
285                                 GFP_NOFS);
286         if (!io_ctl->pages)
287                 return -ENOMEM;
288         io_ctl->root = root;
289         if (btrfs_ino(inode) != BTRFS_FREE_INO_OBJECTID)
290                 io_ctl->check_crcs = 1;
291         return 0;
292 }
293 
294 static void io_ctl_free(struct io_ctl *io_ctl)
295 {
296         kfree(io_ctl->pages);
297 }
298 
299 static void io_ctl_unmap_page(struct io_ctl *io_ctl)
300 {
301         if (io_ctl->cur) {
302                 kunmap(io_ctl->page);
303                 io_ctl->cur = NULL;
304                 io_ctl->orig = NULL;
305         }
306 }
307 
308 static void io_ctl_map_page(struct io_ctl *io_ctl, int clear)
309 {
310         WARN_ON(io_ctl->cur);
311         BUG_ON(io_ctl->index >= io_ctl->num_pages);
312         io_ctl->page = io_ctl->pages[io_ctl->index++];
313         io_ctl->cur = kmap(io_ctl->page);
314         io_ctl->orig = io_ctl->cur;
315         io_ctl->size = PAGE_CACHE_SIZE;
316         if (clear)
317                 memset(io_ctl->cur, 0, PAGE_CACHE_SIZE);
318 }
319 
320 static void io_ctl_drop_pages(struct io_ctl *io_ctl)
321 {
322         int i;
323 
324         io_ctl_unmap_page(io_ctl);
325 
326         for (i = 0; i < io_ctl->num_pages; i++) {
327                 if (io_ctl->pages[i]) {
328                         ClearPageChecked(io_ctl->pages[i]);
329                         unlock_page(io_ctl->pages[i]);
330                         page_cache_release(io_ctl->pages[i]);
331                 }
332         }
333 }
334 
335 static int io_ctl_prepare_pages(struct io_ctl *io_ctl, struct inode *inode,
336                                 int uptodate)
337 {
338         struct page *page;
339         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
340         int i;
341 
342         for (i = 0; i < io_ctl->num_pages; i++) {
343                 page = find_or_create_page(inode->i_mapping, i, mask);
344                 if (!page) {
345                         io_ctl_drop_pages(io_ctl);
346                         return -ENOMEM;
347                 }
348                 io_ctl->pages[i] = page;
349                 if (uptodate && !PageUptodate(page)) {
350                         btrfs_readpage(NULL, page);
351                         lock_page(page);
352                         if (!PageUptodate(page)) {
353                                 printk(KERN_ERR "btrfs: error reading free "
354                                        "space cache\n");
355                                 io_ctl_drop_pages(io_ctl);
356                                 return -EIO;
357                         }
358                 }
359         }
360 
361         for (i = 0; i < io_ctl->num_pages; i++) {
362                 clear_page_dirty_for_io(io_ctl->pages[i]);
363                 set_page_extent_mapped(io_ctl->pages[i]);
364         }
365 
366         return 0;
367 }
368 
369 static void io_ctl_set_generation(struct io_ctl *io_ctl, u64 generation)
370 {
371         __le64 *val;
372 
373         io_ctl_map_page(io_ctl, 1);
374 
375         /*
376          * Skip the csum areas.  If we don't check crcs then we just have a
377          * 64bit chunk at the front of the first page.
378          */
379         if (io_ctl->check_crcs) {
380                 io_ctl->cur += (sizeof(u32) * io_ctl->num_pages);
381                 io_ctl->size -= sizeof(u64) + (sizeof(u32) * io_ctl->num_pages);
382         } else {
383                 io_ctl->cur += sizeof(u64);
384                 io_ctl->size -= sizeof(u64) * 2;
385         }
386 
387         val = io_ctl->cur;
388         *val = cpu_to_le64(generation);
389         io_ctl->cur += sizeof(u64);
390 }
391 
392 static int io_ctl_check_generation(struct io_ctl *io_ctl, u64 generation)
393 {
394         __le64 *gen;
395 
396         /*
397          * Skip the crc area.  If we don't check crcs then we just have a 64bit
398          * chunk at the front of the first page.
399          */
400         if (io_ctl->check_crcs) {
401                 io_ctl->cur += sizeof(u32) * io_ctl->num_pages;
402                 io_ctl->size -= sizeof(u64) +
403                         (sizeof(u32) * io_ctl->num_pages);
404         } else {
405                 io_ctl->cur += sizeof(u64);
406                 io_ctl->size -= sizeof(u64) * 2;
407         }
408 
409         gen = io_ctl->cur;
410         if (le64_to_cpu(*gen) != generation) {
411                 printk_ratelimited(KERN_ERR "btrfs: space cache generation "
412                                    "(%Lu) does not match inode (%Lu)\n", *gen,
413                                    generation);
414                 io_ctl_unmap_page(io_ctl);
415                 return -EIO;
416         }
417         io_ctl->cur += sizeof(u64);
418         return 0;
419 }
420 
421 static void io_ctl_set_crc(struct io_ctl *io_ctl, int index)
422 {
423         u32 *tmp;
424         u32 crc = ~(u32)0;
425         unsigned offset = 0;
426 
427         if (!io_ctl->check_crcs) {
428                 io_ctl_unmap_page(io_ctl);
429                 return;
430         }
431 
432         if (index == 0)
433                 offset = sizeof(u32) * io_ctl->num_pages;
434 
435         crc = btrfs_csum_data(io_ctl->root, io_ctl->orig + offset, crc,
436                               PAGE_CACHE_SIZE - offset);
437         btrfs_csum_final(crc, (char *)&crc);
438         io_ctl_unmap_page(io_ctl);
439         tmp = kmap(io_ctl->pages[0]);
440         tmp += index;
441         *tmp = crc;
442         kunmap(io_ctl->pages[0]);
443 }
444 
445 static int io_ctl_check_crc(struct io_ctl *io_ctl, int index)
446 {
447         u32 *tmp, val;
448         u32 crc = ~(u32)0;
449         unsigned offset = 0;
450 
451         if (!io_ctl->check_crcs) {
452                 io_ctl_map_page(io_ctl, 0);
453                 return 0;
454         }
455 
456         if (index == 0)
457                 offset = sizeof(u32) * io_ctl->num_pages;
458 
459         tmp = kmap(io_ctl->pages[0]);
460         tmp += index;
461         val = *tmp;
462         kunmap(io_ctl->pages[0]);
463 
464         io_ctl_map_page(io_ctl, 0);
465         crc = btrfs_csum_data(io_ctl->root, io_ctl->orig + offset, crc,
466                               PAGE_CACHE_SIZE - offset);
467         btrfs_csum_final(crc, (char *)&crc);
468         if (val != crc) {
469                 printk_ratelimited(KERN_ERR "btrfs: csum mismatch on free "
470                                    "space cache\n");
471                 io_ctl_unmap_page(io_ctl);
472                 return -EIO;
473         }
474 
475         return 0;
476 }
477 
478 static int io_ctl_add_entry(struct io_ctl *io_ctl, u64 offset, u64 bytes,
479                             void *bitmap)
480 {
481         struct btrfs_free_space_entry *entry;
482 
483         if (!io_ctl->cur)
484                 return -ENOSPC;
485 
486         entry = io_ctl->cur;
487         entry->offset = cpu_to_le64(offset);
488         entry->bytes = cpu_to_le64(bytes);
489         entry->type = (bitmap) ? BTRFS_FREE_SPACE_BITMAP :
490                 BTRFS_FREE_SPACE_EXTENT;
491         io_ctl->cur += sizeof(struct btrfs_free_space_entry);
492         io_ctl->size -= sizeof(struct btrfs_free_space_entry);
493 
494         if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
495                 return 0;
496 
497         io_ctl_set_crc(io_ctl, io_ctl->index - 1);
498 
499         /* No more pages to map */
500         if (io_ctl->index >= io_ctl->num_pages)
501                 return 0;
502 
503         /* map the next page */
504         io_ctl_map_page(io_ctl, 1);
505         return 0;
506 }
507 
508 static int io_ctl_add_bitmap(struct io_ctl *io_ctl, void *bitmap)
509 {
510         if (!io_ctl->cur)
511                 return -ENOSPC;
512 
513         /*
514          * If we aren't at the start of the current page, unmap this one and
515          * map the next one if there is any left.
516          */
517         if (io_ctl->cur != io_ctl->orig) {
518                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
519                 if (io_ctl->index >= io_ctl->num_pages)
520                         return -ENOSPC;
521                 io_ctl_map_page(io_ctl, 0);
522         }
523 
524         memcpy(io_ctl->cur, bitmap, PAGE_CACHE_SIZE);
525         io_ctl_set_crc(io_ctl, io_ctl->index - 1);
526         if (io_ctl->index < io_ctl->num_pages)
527                 io_ctl_map_page(io_ctl, 0);
528         return 0;
529 }
530 
531 static void io_ctl_zero_remaining_pages(struct io_ctl *io_ctl)
532 {
533         /*
534          * If we're not on the boundary we know we've modified the page and we
535          * need to crc the page.
536          */
537         if (io_ctl->cur != io_ctl->orig)
538                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
539         else
540                 io_ctl_unmap_page(io_ctl);
541 
542         while (io_ctl->index < io_ctl->num_pages) {
543                 io_ctl_map_page(io_ctl, 1);
544                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
545         }
546 }
547 
548 static int io_ctl_read_entry(struct io_ctl *io_ctl,
549                             struct btrfs_free_space *entry, u8 *type)
550 {
551         struct btrfs_free_space_entry *e;
552         int ret;
553 
554         if (!io_ctl->cur) {
555                 ret = io_ctl_check_crc(io_ctl, io_ctl->index);
556                 if (ret)
557                         return ret;
558         }
559 
560         e = io_ctl->cur;
561         entry->offset = le64_to_cpu(e->offset);
562         entry->bytes = le64_to_cpu(e->bytes);
563         *type = e->type;
564         io_ctl->cur += sizeof(struct btrfs_free_space_entry);
565         io_ctl->size -= sizeof(struct btrfs_free_space_entry);
566 
567         if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
568                 return 0;
569 
570         io_ctl_unmap_page(io_ctl);
571 
572         return 0;
573 }
574 
575 static int io_ctl_read_bitmap(struct io_ctl *io_ctl,
576                               struct btrfs_free_space *entry)
577 {
578         int ret;
579 
580         ret = io_ctl_check_crc(io_ctl, io_ctl->index);
581         if (ret)
582                 return ret;
583 
584         memcpy(entry->bitmap, io_ctl->cur, PAGE_CACHE_SIZE);
585         io_ctl_unmap_page(io_ctl);
586 
587         return 0;
588 }
589 
590 /*
591  * Since we attach pinned extents after the fact we can have contiguous sections
592  * of free space that are split up in entries.  This poses a problem with the
593  * tree logging stuff since it could have allocated across what appears to be 2
594  * entries since we would have merged the entries when adding the pinned extents
595  * back to the free space cache.  So run through the space cache that we just
596  * loaded and merge contiguous entries.  This will make the log replay stuff not
597  * blow up and it will make for nicer allocator behavior.
598  */
599 static void merge_space_tree(struct btrfs_free_space_ctl *ctl)
600 {
601         struct btrfs_free_space *e, *prev = NULL;
602         struct rb_node *n;
603 
604 again:
605         spin_lock(&ctl->tree_lock);
606         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
607                 e = rb_entry(n, struct btrfs_free_space, offset_index);
608                 if (!prev)
609                         goto next;
610                 if (e->bitmap || prev->bitmap)
611                         goto next;
612                 if (prev->offset + prev->bytes == e->offset) {
613                         unlink_free_space(ctl, prev);
614                         unlink_free_space(ctl, e);
615                         prev->bytes += e->bytes;
616                         kmem_cache_free(btrfs_free_space_cachep, e);
617                         link_free_space(ctl, prev);
618                         prev = NULL;
619                         spin_unlock(&ctl->tree_lock);
620                         goto again;
621                 }
622 next:
623                 prev = e;
624         }
625         spin_unlock(&ctl->tree_lock);
626 }
627 
628 int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
629                             struct btrfs_free_space_ctl *ctl,
630                             struct btrfs_path *path, u64 offset)
631 {
632         struct btrfs_free_space_header *header;
633         struct extent_buffer *leaf;
634         struct io_ctl io_ctl;
635         struct btrfs_key key;
636         struct btrfs_free_space *e, *n;
637         struct list_head bitmaps;
638         u64 num_entries;
639         u64 num_bitmaps;
640         u64 generation;
641         u8 type;
642         int ret = 0;
643 
644         INIT_LIST_HEAD(&bitmaps);
645 
646         /* Nothing in the space cache, goodbye */
647         if (!i_size_read(inode))
648                 return 0;
649 
650         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
651         key.offset = offset;
652         key.type = 0;
653 
654         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
655         if (ret < 0)
656                 return 0;
657         else if (ret > 0) {
658                 btrfs_release_path(path);
659                 return 0;
660         }
661 
662         ret = -1;
663 
664         leaf = path->nodes[0];
665         header = btrfs_item_ptr(leaf, path->slots[0],
666                                 struct btrfs_free_space_header);
667         num_entries = btrfs_free_space_entries(leaf, header);
668         num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
669         generation = btrfs_free_space_generation(leaf, header);
670         btrfs_release_path(path);
671 
672         if (BTRFS_I(inode)->generation != generation) {
673                 printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
674                        " not match free space cache generation (%llu)\n",
675                        (unsigned long long)BTRFS_I(inode)->generation,
676                        (unsigned long long)generation);
677                 return 0;
678         }
679 
680         if (!num_entries)
681                 return 0;
682 
683         ret = io_ctl_init(&io_ctl, inode, root);
684         if (ret)
685                 return ret;
686 
687         ret = readahead_cache(inode);
688         if (ret)
689                 goto out;
690 
691         ret = io_ctl_prepare_pages(&io_ctl, inode, 1);
692         if (ret)
693                 goto out;
694 
695         ret = io_ctl_check_crc(&io_ctl, 0);
696         if (ret)
697                 goto free_cache;
698 
699         ret = io_ctl_check_generation(&io_ctl, generation);
700         if (ret)
701                 goto free_cache;
702 
703         while (num_entries) {
704                 e = kmem_cache_zalloc(btrfs_free_space_cachep,
705                                       GFP_NOFS);
706                 if (!e)
707                         goto free_cache;
708 
709                 ret = io_ctl_read_entry(&io_ctl, e, &type);
710                 if (ret) {
711                         kmem_cache_free(btrfs_free_space_cachep, e);
712                         goto free_cache;
713                 }
714 
715                 if (!e->bytes) {
716                         kmem_cache_free(btrfs_free_space_cachep, e);
717                         goto free_cache;
718                 }
719 
720                 if (type == BTRFS_FREE_SPACE_EXTENT) {
721                         spin_lock(&ctl->tree_lock);
722                         ret = link_free_space(ctl, e);
723                         spin_unlock(&ctl->tree_lock);
724                         if (ret) {
725                                 printk(KERN_ERR "Duplicate entries in "
726                                        "free space cache, dumping\n");
727                                 kmem_cache_free(btrfs_free_space_cachep, e);
728                                 goto free_cache;
729                         }
730                 } else {
731                         BUG_ON(!num_bitmaps);
732                         num_bitmaps--;
733                         e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
734                         if (!e->bitmap) {
735                                 kmem_cache_free(
736                                         btrfs_free_space_cachep, e);
737                                 goto free_cache;
738                         }
739                         spin_lock(&ctl->tree_lock);
740                         ret = link_free_space(ctl, e);
741                         ctl->total_bitmaps++;
742                         ctl->op->recalc_thresholds(ctl);
743                         spin_unlock(&ctl->tree_lock);
744                         if (ret) {
745                                 printk(KERN_ERR "Duplicate entries in "
746                                        "free space cache, dumping\n");
747                                 kmem_cache_free(btrfs_free_space_cachep, e);
748                                 goto free_cache;
749                         }
750                         list_add_tail(&e->list, &bitmaps);
751                 }
752 
753                 num_entries--;
754         }
755 
756         io_ctl_unmap_page(&io_ctl);
757 
758         /*
759          * We add the bitmaps at the end of the entries in order that
760          * the bitmap entries are added to the cache.
761          */
762         list_for_each_entry_safe(e, n, &bitmaps, list) {
763                 list_del_init(&e->list);
764                 ret = io_ctl_read_bitmap(&io_ctl, e);
765                 if (ret)
766                         goto free_cache;
767         }
768 
769         io_ctl_drop_pages(&io_ctl);
770         merge_space_tree(ctl);
771         ret = 1;
772 out:
773         io_ctl_free(&io_ctl);
774         return ret;
775 free_cache:
776         io_ctl_drop_pages(&io_ctl);
777         __btrfs_remove_free_space_cache(ctl);
778         goto out;
779 }
780 
781 int load_free_space_cache(struct btrfs_fs_info *fs_info,
782                           struct btrfs_block_group_cache *block_group)
783 {
784         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
785         struct btrfs_root *root = fs_info->tree_root;
786         struct inode *inode;
787         struct btrfs_path *path;
788         int ret = 0;
789         bool matched;
790         u64 used = btrfs_block_group_used(&block_group->item);
791 
792         /*
793          * If this block group has been marked to be cleared for one reason or
794          * another then we can't trust the on disk cache, so just return.
795          */
796         spin_lock(&block_group->lock);
797         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
798                 spin_unlock(&block_group->lock);
799                 return 0;
800         }
801         spin_unlock(&block_group->lock);
802 
803         path = btrfs_alloc_path();
804         if (!path)
805                 return 0;
806         path->search_commit_root = 1;
807         path->skip_locking = 1;
808 
809         inode = lookup_free_space_inode(root, block_group, path);
810         if (IS_ERR(inode)) {
811                 btrfs_free_path(path);
812                 return 0;
813         }
814 
815         /* We may have converted the inode and made the cache invalid. */
816         spin_lock(&block_group->lock);
817         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
818                 spin_unlock(&block_group->lock);
819                 btrfs_free_path(path);
820                 goto out;
821         }
822         spin_unlock(&block_group->lock);
823 
824         ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
825                                       path, block_group->key.objectid);
826         btrfs_free_path(path);
827         if (ret <= 0)
828                 goto out;
829 
830         spin_lock(&ctl->tree_lock);
831         matched = (ctl->free_space == (block_group->key.offset - used -
832                                        block_group->bytes_super));
833         spin_unlock(&ctl->tree_lock);
834 
835         if (!matched) {
836                 __btrfs_remove_free_space_cache(ctl);
837                 printk(KERN_ERR "block group %llu has an wrong amount of free "
838                        "space\n", block_group->key.objectid);
839                 ret = -1;
840         }
841 out:
842         if (ret < 0) {
843                 /* This cache is bogus, make sure it gets cleared */
844                 spin_lock(&block_group->lock);
845                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
846                 spin_unlock(&block_group->lock);
847                 ret = 0;
848 
849                 printk(KERN_ERR "btrfs: failed to load free space cache "
850                        "for block group %llu\n", block_group->key.objectid);
851         }
852 
853         iput(inode);
854         return ret;
855 }
856 
857 /**
858  * __btrfs_write_out_cache - write out cached info to an inode
859  * @root - the root the inode belongs to
860  * @ctl - the free space cache we are going to write out
861  * @block_group - the block_group for this cache if it belongs to a block_group
862  * @trans - the trans handle
863  * @path - the path to use
864  * @offset - the offset for the key we'll insert
865  *
866  * This function writes out a free space cache struct to disk for quick recovery
867  * on mount.  This will return 0 if it was successfull in writing the cache out,
868  * and -1 if it was not.
869  */
870 int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
871                             struct btrfs_free_space_ctl *ctl,
872                             struct btrfs_block_group_cache *block_group,
873                             struct btrfs_trans_handle *trans,
874                             struct btrfs_path *path, u64 offset)
875 {
876         struct btrfs_free_space_header *header;
877         struct extent_buffer *leaf;
878         struct rb_node *node;
879         struct list_head *pos, *n;
880         struct extent_state *cached_state = NULL;
881         struct btrfs_free_cluster *cluster = NULL;
882         struct extent_io_tree *unpin = NULL;
883         struct io_ctl io_ctl;
884         struct list_head bitmap_list;
885         struct btrfs_key key;
886         u64 start, extent_start, extent_end, len;
887         int entries = 0;
888         int bitmaps = 0;
889         int ret;
890         int err = -1;
891 
892         INIT_LIST_HEAD(&bitmap_list);
893 
894         if (!i_size_read(inode))
895                 return -1;
896 
897         ret = io_ctl_init(&io_ctl, inode, root);
898         if (ret)
899                 return -1;
900 
901         /* Get the cluster for this block_group if it exists */
902         if (block_group && !list_empty(&block_group->cluster_list))
903                 cluster = list_entry(block_group->cluster_list.next,
904                                      struct btrfs_free_cluster,
905                                      block_group_list);
906 
907         /* Lock all pages first so we can lock the extent safely. */
908         io_ctl_prepare_pages(&io_ctl, inode, 0);
909 
910         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
911                          0, &cached_state);
912 
913         node = rb_first(&ctl->free_space_offset);
914         if (!node && cluster) {
915                 node = rb_first(&cluster->root);
916                 cluster = NULL;
917         }
918 
919         /* Make sure we can fit our crcs into the first page */
920         if (io_ctl.check_crcs &&
921             (io_ctl.num_pages * sizeof(u32)) >= PAGE_CACHE_SIZE) {
922                 WARN_ON(1);
923                 goto out_nospc;
924         }
925 
926         io_ctl_set_generation(&io_ctl, trans->transid);
927 
928         /* Write out the extent entries */
929         while (node) {
930                 struct btrfs_free_space *e;
931 
932                 e = rb_entry(node, struct btrfs_free_space, offset_index);
933                 entries++;
934 
935                 ret = io_ctl_add_entry(&io_ctl, e->offset, e->bytes,
936                                        e->bitmap);
937                 if (ret)
938                         goto out_nospc;
939 
940                 if (e->bitmap) {
941                         list_add_tail(&e->list, &bitmap_list);
942                         bitmaps++;
943                 }
944                 node = rb_next(node);
945                 if (!node && cluster) {
946                         node = rb_first(&cluster->root);
947                         cluster = NULL;
948                 }
949         }
950 
951         /*
952          * We want to add any pinned extents to our free space cache
953          * so we don't leak the space
954          */
955 
956         /*
957          * We shouldn't have switched the pinned extents yet so this is the
958          * right one
959          */
960         unpin = root->fs_info->pinned_extents;
961 
962         if (block_group)
963                 start = block_group->key.objectid;
964 
965         while (block_group && (start < block_group->key.objectid +
966                                block_group->key.offset)) {
967                 ret = find_first_extent_bit(unpin, start,
968                                             &extent_start, &extent_end,
969                                             EXTENT_DIRTY);
970                 if (ret) {
971                         ret = 0;
972                         break;
973                 }
974 
975                 /* This pinned extent is out of our range */
976                 if (extent_start >= block_group->key.objectid +
977                     block_group->key.offset)
978                         break;
979 
980                 extent_start = max(extent_start, start);
981                 extent_end = min(block_group->key.objectid +
982                                  block_group->key.offset, extent_end + 1);
983                 len = extent_end - extent_start;
984 
985                 entries++;
986                 ret = io_ctl_add_entry(&io_ctl, extent_start, len, NULL);
987                 if (ret)
988                         goto out_nospc;
989 
990                 start = extent_end;
991         }
992 
993         /* Write out the bitmaps */
994         list_for_each_safe(pos, n, &bitmap_list) {
995                 struct btrfs_free_space *entry =
996                         list_entry(pos, struct btrfs_free_space, list);
997 
998                 ret = io_ctl_add_bitmap(&io_ctl, entry->bitmap);
999                 if (ret)
1000                         goto out_nospc;
1001                 list_del_init(&entry->list);
1002         }
1003 
1004         /* Zero out the rest of the pages just to make sure */
1005         io_ctl_zero_remaining_pages(&io_ctl);
1006 
1007         ret = btrfs_dirty_pages(root, inode, io_ctl.pages, io_ctl.num_pages,
1008                                 0, i_size_read(inode), &cached_state);
1009         io_ctl_drop_pages(&io_ctl);
1010         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
1011                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
1012 
1013         if (ret)
1014                 goto out;
1015 
1016 
1017         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1018 
1019         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
1020         key.offset = offset;
1021         key.type = 0;
1022 
1023         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
1024         if (ret < 0) {
1025                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
1026                                  EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL,
1027                                  GFP_NOFS);
1028                 goto out;
1029         }
1030         leaf = path->nodes[0];
1031         if (ret > 0) {
1032                 struct btrfs_key found_key;
1033                 BUG_ON(!path->slots[0]);
1034                 path->slots[0]--;
1035                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1036                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
1037                     found_key.offset != offset) {
1038                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0,
1039                                          inode->i_size - 1,
1040                                          EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0,
1041                                          NULL, GFP_NOFS);
1042                         btrfs_release_path(path);
1043                         goto out;
1044                 }
1045         }
1046 
1047         BTRFS_I(inode)->generation = trans->transid;
1048         header = btrfs_item_ptr(leaf, path->slots[0],
1049                                 struct btrfs_free_space_header);
1050         btrfs_set_free_space_entries(leaf, header, entries);
1051         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
1052         btrfs_set_free_space_generation(leaf, header, trans->transid);
1053         btrfs_mark_buffer_dirty(leaf);
1054         btrfs_release_path(path);
1055 
1056         err = 0;
1057 out:
1058         io_ctl_free(&io_ctl);
1059         if (err) {
1060                 invalidate_inode_pages2(inode->i_mapping);
1061                 BTRFS_I(inode)->generation = 0;
1062         }
1063         btrfs_update_inode(trans, root, inode);
1064         return err;
1065 
1066 out_nospc:
1067         list_for_each_safe(pos, n, &bitmap_list) {
1068                 struct btrfs_free_space *entry =
1069                         list_entry(pos, struct btrfs_free_space, list);
1070                 list_del_init(&entry->list);
1071         }
1072         io_ctl_drop_pages(&io_ctl);
1073         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
1074                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
1075         goto out;
1076 }
1077 
1078 int btrfs_write_out_cache(struct btrfs_root *root,
1079                           struct btrfs_trans_handle *trans,
1080                           struct btrfs_block_group_cache *block_group,
1081                           struct btrfs_path *path)
1082 {
1083         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1084         struct inode *inode;
1085         int ret = 0;
1086 
1087         root = root->fs_info->tree_root;
1088 
1089         spin_lock(&block_group->lock);
1090         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
1091                 spin_unlock(&block_group->lock);
1092                 return 0;
1093         }
1094         spin_unlock(&block_group->lock);
1095 
1096         inode = lookup_free_space_inode(root, block_group, path);
1097         if (IS_ERR(inode))
1098                 return 0;
1099 
1100         ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
1101                                       path, block_group->key.objectid);
1102         if (ret) {
1103                 spin_lock(&block_group->lock);
1104                 block_group->disk_cache_state = BTRFS_DC_ERROR;
1105                 spin_unlock(&block_group->lock);
1106                 ret = 0;
1107 #ifdef DEBUG
1108                 printk(KERN_ERR "btrfs: failed to write free space cache "
1109                        "for block group %llu\n", block_group->key.objectid);
1110 #endif
1111         }
1112 
1113         iput(inode);
1114         return ret;
1115 }
1116 
1117 static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
1118                                           u64 offset)
1119 {
1120         BUG_ON(offset < bitmap_start);
1121         offset -= bitmap_start;
1122         return (unsigned long)(div_u64(offset, unit));
1123 }
1124 
1125 static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
1126 {
1127         return (unsigned long)(div_u64(bytes, unit));
1128 }
1129 
1130 static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
1131                                    u64 offset)
1132 {
1133         u64 bitmap_start;
1134         u64 bytes_per_bitmap;
1135 
1136         bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
1137         bitmap_start = offset - ctl->start;
1138         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
1139         bitmap_start *= bytes_per_bitmap;
1140         bitmap_start += ctl->start;
1141 
1142         return bitmap_start;
1143 }
1144 
1145 static int tree_insert_offset(struct rb_root *root, u64 offset,
1146                               struct rb_node *node, int bitmap)
1147 {
1148         struct rb_node **p = &root->rb_node;
1149         struct rb_node *parent = NULL;
1150         struct btrfs_free_space *info;
1151 
1152         while (*p) {
1153                 parent = *p;
1154                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
1155 
1156                 if (offset < info->offset) {
1157                         p = &(*p)->rb_left;
1158                 } else if (offset > info->offset) {
1159                         p = &(*p)->rb_right;
1160                 } else {
1161                         /*
1162                          * we could have a bitmap entry and an extent entry
1163                          * share the same offset.  If this is the case, we want
1164                          * the extent entry to always be found first if we do a
1165                          * linear search through the tree, since we want to have
1166                          * the quickest allocation time, and allocating from an
1167                          * extent is faster than allocating from a bitmap.  So
1168                          * if we're inserting a bitmap and we find an entry at
1169                          * this offset, we want to go right, or after this entry
1170                          * logically.  If we are inserting an extent and we've
1171                          * found a bitmap, we want to go left, or before
1172                          * logically.
1173                          */
1174                         if (bitmap) {
1175                                 if (info->bitmap) {
1176                                         WARN_ON_ONCE(1);
1177                                         return -EEXIST;
1178                                 }
1179                                 p = &(*p)->rb_right;
1180                         } else {
1181                                 if (!info->bitmap) {
1182                                         WARN_ON_ONCE(1);
1183                                         return -EEXIST;
1184                                 }
1185                                 p = &(*p)->rb_left;
1186                         }
1187                 }
1188         }
1189 
1190         rb_link_node(node, parent, p);
1191         rb_insert_color(node, root);
1192 
1193         return 0;
1194 }
1195 
1196 /*
1197  * searches the tree for the given offset.
1198  *
1199  * fuzzy - If this is set, then we are trying to make an allocation, and we just
1200  * want a section that has at least bytes size and comes at or after the given
1201  * offset.
1202  */
1203 static struct btrfs_free_space *
1204 tree_search_offset(struct btrfs_free_space_ctl *ctl,
1205                    u64 offset, int bitmap_only, int fuzzy)
1206 {
1207         struct rb_node *n = ctl->free_space_offset.rb_node;
1208         struct btrfs_free_space *entry, *prev = NULL;
1209 
1210         /* find entry that is closest to the 'offset' */
1211         while (1) {
1212                 if (!n) {
1213                         entry = NULL;
1214                         break;
1215                 }
1216 
1217                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1218                 prev = entry;
1219 
1220                 if (offset < entry->offset)
1221                         n = n->rb_left;
1222                 else if (offset > entry->offset)
1223                         n = n->rb_right;
1224                 else
1225                         break;
1226         }
1227 
1228         if (bitmap_only) {
1229                 if (!entry)
1230                         return NULL;
1231                 if (entry->bitmap)
1232                         return entry;
1233 
1234                 /*
1235                  * bitmap entry and extent entry may share same offset,
1236                  * in that case, bitmap entry comes after extent entry.
1237                  */
1238                 n = rb_next(n);
1239                 if (!n)
1240                         return NULL;
1241                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1242                 if (entry->offset != offset)
1243                         return NULL;
1244 
1245                 WARN_ON(!entry->bitmap);
1246                 return entry;
1247         } else if (entry) {
1248                 if (entry->bitmap) {
1249                         /*
1250                          * if previous extent entry covers the offset,
1251                          * we should return it instead of the bitmap entry
1252                          */
1253                         n = &entry->offset_index;
1254                         while (1) {
1255                                 n = rb_prev(n);
1256                                 if (!n)
1257                                         break;
1258                                 prev = rb_entry(n, struct btrfs_free_space,
1259                                                 offset_index);
1260                                 if (!prev->bitmap) {
1261                                         if (prev->offset + prev->bytes > offset)
1262                                                 entry = prev;
1263                                         break;
1264                                 }
1265                         }
1266                 }
1267                 return entry;
1268         }
1269 
1270         if (!prev)
1271                 return NULL;
1272 
1273         /* find last entry before the 'offset' */
1274         entry = prev;
1275         if (entry->offset > offset) {
1276                 n = rb_prev(&entry->offset_index);
1277                 if (n) {
1278                         entry = rb_entry(n, struct btrfs_free_space,
1279                                         offset_index);
1280                         BUG_ON(entry->offset > offset);
1281                 } else {
1282                         if (fuzzy)
1283                                 return entry;
1284                         else
1285                                 return NULL;
1286                 }
1287         }
1288 
1289         if (entry->bitmap) {
1290                 n = &entry->offset_index;
1291                 while (1) {
1292                         n = rb_prev(n);
1293                         if (!n)
1294                                 break;
1295                         prev = rb_entry(n, struct btrfs_free_space,
1296                                         offset_index);
1297                         if (!prev->bitmap) {
1298                                 if (prev->offset + prev->bytes > offset)
1299                                         return prev;
1300                                 break;
1301                         }
1302                 }
1303                 if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1304                         return entry;
1305         } else if (entry->offset + entry->bytes > offset)
1306                 return entry;
1307 
1308         if (!fuzzy)
1309                 return NULL;
1310 
1311         while (1) {
1312                 if (entry->bitmap) {
1313                         if (entry->offset + BITS_PER_BITMAP *
1314                             ctl->unit > offset)
1315                                 break;
1316                 } else {
1317                         if (entry->offset + entry->bytes > offset)
1318                                 break;
1319                 }
1320 
1321                 n = rb_next(&entry->offset_index);
1322                 if (!n)
1323                         return NULL;
1324                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1325         }
1326         return entry;
1327 }
1328 
1329 static inline void
1330 __unlink_free_space(struct btrfs_free_space_ctl *ctl,
1331                     struct btrfs_free_space *info)
1332 {
1333         rb_erase(&info->offset_index, &ctl->free_space_offset);
1334         ctl->free_extents--;
1335 }
1336 
1337 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1338                               struct btrfs_free_space *info)
1339 {
1340         __unlink_free_space(ctl, info);
1341         ctl->free_space -= info->bytes;
1342 }
1343 
1344 static int link_free_space(struct btrfs_free_space_ctl *ctl,
1345                            struct btrfs_free_space *info)
1346 {
1347         int ret = 0;
1348 
1349         BUG_ON(!info->bitmap && !info->bytes);
1350         ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1351                                  &info->offset_index, (info->bitmap != NULL));
1352         if (ret)
1353                 return ret;
1354 
1355         ctl->free_space += info->bytes;
1356         ctl->free_extents++;
1357         return ret;
1358 }
1359 
1360 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1361 {
1362         struct btrfs_block_group_cache *block_group = ctl->private;
1363         u64 max_bytes;
1364         u64 bitmap_bytes;
1365         u64 extent_bytes;
1366         u64 size = block_group->key.offset;
1367         u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
1368         int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1369 
1370         BUG_ON(ctl->total_bitmaps > max_bitmaps);
1371 
1372         /*
1373          * The goal is to keep the total amount of memory used per 1gb of space
1374          * at or below 32k, so we need to adjust how much memory we allow to be
1375          * used by extent based free space tracking
1376          */
1377         if (size < 1024 * 1024 * 1024)
1378                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1379         else
1380                 max_bytes = MAX_CACHE_BYTES_PER_GIG *
1381                         div64_u64(size, 1024 * 1024 * 1024);
1382 
1383         /*
1384          * we want to account for 1 more bitmap than what we have so we can make
1385          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1386          * we add more bitmaps.
1387          */
1388         bitmap_bytes = (ctl->total_bitmaps + 1) * PAGE_CACHE_SIZE;
1389 
1390         if (bitmap_bytes >= max_bytes) {
1391                 ctl->extents_thresh = 0;
1392                 return;
1393         }
1394 
1395         /*
1396          * we want the extent entry threshold to always be at most 1/2 the maxw
1397          * bytes we can have, or whatever is less than that.
1398          */
1399         extent_bytes = max_bytes - bitmap_bytes;
1400         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
1401 
1402         ctl->extents_thresh =
1403                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
1404 }
1405 
1406 static inline void __bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1407                                        struct btrfs_free_space *info,
1408                                        u64 offset, u64 bytes)
1409 {
1410         unsigned long start, count;
1411 
1412         start = offset_to_bit(info->offset, ctl->unit, offset);
1413         count = bytes_to_bits(bytes, ctl->unit);
1414         BUG_ON(start + count > BITS_PER_BITMAP);
1415 
1416         bitmap_clear(info->bitmap, start, count);
1417 
1418         info->bytes -= bytes;
1419 }
1420 
1421 static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1422                               struct btrfs_free_space *info, u64 offset,
1423                               u64 bytes)
1424 {
1425         __bitmap_clear_bits(ctl, info, offset, bytes);
1426         ctl->free_space -= bytes;
1427 }
1428 
1429 static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1430                             struct btrfs_free_space *info, u64 offset,
1431                             u64 bytes)
1432 {
1433         unsigned long start, count;
1434 
1435         start = offset_to_bit(info->offset, ctl->unit, offset);
1436         count = bytes_to_bits(bytes, ctl->unit);
1437         BUG_ON(start + count > BITS_PER_BITMAP);
1438 
1439         bitmap_set(info->bitmap, start, count);
1440 
1441         info->bytes += bytes;
1442         ctl->free_space += bytes;
1443 }
1444 
1445 static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1446                          struct btrfs_free_space *bitmap_info, u64 *offset,
1447                          u64 *bytes)
1448 {
1449         unsigned long found_bits = 0;
1450         unsigned long bits, i;
1451         unsigned long next_zero;
1452 
1453         i = offset_to_bit(bitmap_info->offset, ctl->unit,
1454                           max_t(u64, *offset, bitmap_info->offset));
1455         bits = bytes_to_bits(*bytes, ctl->unit);
1456 
1457         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
1458              i < BITS_PER_BITMAP;
1459              i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
1460                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1461                                                BITS_PER_BITMAP, i);
1462                 if ((next_zero - i) >= bits) {
1463                         found_bits = next_zero - i;
1464                         break;
1465                 }
1466                 i = next_zero;
1467         }
1468 
1469         if (found_bits) {
1470                 *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1471                 *bytes = (u64)(found_bits) * ctl->unit;
1472                 return 0;
1473         }
1474 
1475         return -1;
1476 }
1477 
1478 static struct btrfs_free_space *
1479 find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes)
1480 {
1481         struct btrfs_free_space *entry;
1482         struct rb_node *node;
1483         int ret;
1484 
1485         if (!ctl->free_space_offset.rb_node)
1486                 return NULL;
1487 
1488         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1489         if (!entry)
1490                 return NULL;
1491 
1492         for (node = &entry->offset_index; node; node = rb_next(node)) {
1493                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1494                 if (entry->bytes < *bytes)
1495                         continue;
1496 
1497                 if (entry->bitmap) {
1498                         ret = search_bitmap(ctl, entry, offset, bytes);
1499                         if (!ret)
1500                                 return entry;
1501                         continue;
1502                 }
1503 
1504                 *offset = entry->offset;
1505                 *bytes = entry->bytes;
1506                 return entry;
1507         }
1508 
1509         return NULL;
1510 }
1511 
1512 static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1513                            struct btrfs_free_space *info, u64 offset)
1514 {
1515         info->offset = offset_to_bitmap(ctl, offset);
1516         info->bytes = 0;
1517         INIT_LIST_HEAD(&info->list);
1518         link_free_space(ctl, info);
1519         ctl->total_bitmaps++;
1520 
1521         ctl->op->recalc_thresholds(ctl);
1522 }
1523 
1524 static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1525                         struct btrfs_free_space *bitmap_info)
1526 {
1527         unlink_free_space(ctl, bitmap_info);
1528         kfree(bitmap_info->bitmap);
1529         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1530         ctl->total_bitmaps--;
1531         ctl->op->recalc_thresholds(ctl);
1532 }
1533 
1534 static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1535                               struct btrfs_free_space *bitmap_info,
1536                               u64 *offset, u64 *bytes)
1537 {
1538         u64 end;
1539         u64 search_start, search_bytes;
1540         int ret;
1541 
1542 again:
1543         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1544 
1545         /*
1546          * We need to search for bits in this bitmap.  We could only cover some
1547          * of the extent in this bitmap thanks to how we add space, so we need
1548          * to search for as much as it as we can and clear that amount, and then
1549          * go searching for the next bit.
1550          */
1551         search_start = *offset;
1552         search_bytes = ctl->unit;
1553         search_bytes = min(search_bytes, end - search_start + 1);
1554         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
1555         BUG_ON(ret < 0 || search_start != *offset);
1556 
1557         /* We may have found more bits than what we need */
1558         search_bytes = min(search_bytes, *bytes);
1559 
1560         /* Cannot clear past the end of the bitmap */
1561         search_bytes = min(search_bytes, end - search_start + 1);
1562 
1563         bitmap_clear_bits(ctl, bitmap_info, search_start, search_bytes);
1564         *offset += search_bytes;
1565         *bytes -= search_bytes;
1566 
1567         if (*bytes) {
1568                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1569                 if (!bitmap_info->bytes)
1570                         free_bitmap(ctl, bitmap_info);
1571 
1572                 /*
1573                  * no entry after this bitmap, but we still have bytes to
1574                  * remove, so something has gone wrong.
1575                  */
1576                 if (!next)
1577                         return -EINVAL;
1578 
1579                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1580                                        offset_index);
1581 
1582                 /*
1583                  * if the next entry isn't a bitmap we need to return to let the
1584                  * extent stuff do its work.
1585                  */
1586                 if (!bitmap_info->bitmap)
1587                         return -EAGAIN;
1588 
1589                 /*
1590                  * Ok the next item is a bitmap, but it may not actually hold
1591                  * the information for the rest of this free space stuff, so
1592                  * look for it, and if we don't find it return so we can try
1593                  * everything over again.
1594                  */
1595                 search_start = *offset;
1596                 search_bytes = ctl->unit;
1597                 ret = search_bitmap(ctl, bitmap_info, &search_start,
1598                                     &search_bytes);
1599                 if (ret < 0 || search_start != *offset)
1600                         return -EAGAIN;
1601 
1602                 goto again;
1603         } else if (!bitmap_info->bytes)
1604                 free_bitmap(ctl, bitmap_info);
1605 
1606         return 0;
1607 }
1608 
1609 static u64 add_bytes_to_bitmap(struct btrfs_free_space_ctl *ctl,
1610                                struct btrfs_free_space *info, u64 offset,
1611                                u64 bytes)
1612 {
1613         u64 bytes_to_set = 0;
1614         u64 end;
1615 
1616         end = info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1617 
1618         bytes_to_set = min(end - offset, bytes);
1619 
1620         bitmap_set_bits(ctl, info, offset, bytes_to_set);
1621 
1622         return bytes_to_set;
1623 
1624 }
1625 
1626 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1627                       struct btrfs_free_space *info)
1628 {
1629         struct btrfs_block_group_cache *block_group = ctl->private;
1630 
1631         /*
1632          * If we are below the extents threshold then we can add this as an
1633          * extent, and don't have to deal with the bitmap
1634          */
1635         if (ctl->free_extents < ctl->extents_thresh) {
1636                 /*
1637                  * If this block group has some small extents we don't want to
1638                  * use up all of our free slots in the cache with them, we want
1639                  * to reserve them to larger extents, however if we have plent
1640                  * of cache left then go ahead an dadd them, no sense in adding
1641                  * the overhead of a bitmap if we don't have to.
1642                  */
1643                 if (info->bytes <= block_group->sectorsize * 4) {
1644                         if (ctl->free_extents * 2 <= ctl->extents_thresh)
1645                                 return false;
1646                 } else {
1647                         return false;
1648                 }
1649         }
1650 
1651         /*
1652          * some block groups are so tiny they can't be enveloped by a bitmap, so
1653          * don't even bother to create a bitmap for this
1654          */
1655         if (BITS_PER_BITMAP * block_group->sectorsize >
1656             block_group->key.offset)
1657                 return false;
1658 
1659         return true;
1660 }
1661 
1662 static struct btrfs_free_space_op free_space_op = {
1663         .recalc_thresholds      = recalculate_thresholds,
1664         .use_bitmap             = use_bitmap,
1665 };
1666 
1667 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
1668                               struct btrfs_free_space *info)
1669 {
1670         struct btrfs_free_space *bitmap_info;
1671         struct btrfs_block_group_cache *block_group = NULL;
1672         int added = 0;
1673         u64 bytes, offset, bytes_added;
1674         int ret;
1675 
1676         bytes = info->bytes;
1677         offset = info->offset;
1678 
1679         if (!ctl->op->use_bitmap(ctl, info))
1680                 return 0;
1681 
1682         if (ctl->op == &free_space_op)
1683                 block_group = ctl->private;
1684 again:
1685         /*
1686          * Since we link bitmaps right into the cluster we need to see if we
1687          * have a cluster here, and if so and it has our bitmap we need to add
1688          * the free space to that bitmap.
1689          */
1690         if (block_group && !list_empty(&block_group->cluster_list)) {
1691                 struct btrfs_free_cluster *cluster;
1692                 struct rb_node *node;
1693                 struct btrfs_free_space *entry;
1694 
1695                 cluster = list_entry(block_group->cluster_list.next,
1696                                      struct btrfs_free_cluster,
1697                                      block_group_list);
1698                 spin_lock(&cluster->lock);
1699                 node = rb_first(&cluster->root);
1700                 if (!node) {
1701                         spin_unlock(&cluster->lock);
1702                         goto no_cluster_bitmap;
1703                 }
1704 
1705                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1706                 if (!entry->bitmap) {
1707                         spin_unlock(&cluster->lock);
1708                         goto no_cluster_bitmap;
1709                 }
1710 
1711                 if (entry->offset == offset_to_bitmap(ctl, offset)) {
1712                         bytes_added = add_bytes_to_bitmap(ctl, entry,
1713                                                           offset, bytes);
1714                         bytes -= bytes_added;
1715                         offset += bytes_added;
1716                 }
1717                 spin_unlock(&cluster->lock);
1718                 if (!bytes) {
1719                         ret = 1;
1720                         goto out;
1721                 }
1722         }
1723 
1724 no_cluster_bitmap:
1725         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1726                                          1, 0);
1727         if (!bitmap_info) {
1728                 BUG_ON(added);
1729                 goto new_bitmap;
1730         }
1731 
1732         bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
1733         bytes -= bytes_added;
1734         offset += bytes_added;
1735         added = 0;
1736 
1737         if (!bytes) {
1738                 ret = 1;
1739                 goto out;
1740         } else
1741                 goto again;
1742 
1743 new_bitmap:
1744         if (info && info->bitmap) {
1745                 add_new_bitmap(ctl, info, offset);
1746                 added = 1;
1747                 info = NULL;
1748                 goto again;
1749         } else {
1750                 spin_unlock(&ctl->tree_lock);
1751 
1752                 /* no pre-allocated info, allocate a new one */
1753                 if (!info) {
1754                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1755                                                  GFP_NOFS);
1756                         if (!info) {
1757                                 spin_lock(&ctl->tree_lock);
1758                                 ret = -ENOMEM;
1759                                 goto out;
1760                         }
1761                 }
1762 
1763                 /* allocate the bitmap */
1764                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1765                 spin_lock(&ctl->tree_lock);
1766                 if (!info->bitmap) {
1767                         ret = -ENOMEM;
1768                         goto out;
1769                 }
1770                 goto again;
1771         }
1772 
1773 out:
1774         if (info) {
1775                 if (info->bitmap)
1776                         kfree(info->bitmap);
1777                 kmem_cache_free(btrfs_free_space_cachep, info);
1778         }
1779 
1780         return ret;
1781 }
1782 
1783 static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
1784                           struct btrfs_free_space *info, bool update_stat)
1785 {
1786         struct btrfs_free_space *left_info;
1787         struct btrfs_free_space *right_info;
1788         bool merged = false;
1789         u64 offset = info->offset;
1790         u64 bytes = info->bytes;
1791 
1792         /*
1793          * first we want to see if there is free space adjacent to the range we
1794          * are adding, if there is remove that struct and add a new one to
1795          * cover the entire range
1796          */
1797         right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
1798         if (right_info && rb_prev(&right_info->offset_index))
1799                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1800                                      struct btrfs_free_space, offset_index);
1801         else
1802                 left_info = tree_search_offset(ctl, offset - 1, 0, 0);
1803 
1804         if (right_info && !right_info->bitmap) {
1805                 if (update_stat)
1806                         unlink_free_space(ctl, right_info);
1807                 else
1808                         __unlink_free_space(ctl, right_info);
1809                 info->bytes += right_info->bytes;
1810                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1811                 merged = true;
1812         }
1813 
1814         if (left_info && !left_info->bitmap &&
1815             left_info->offset + left_info->bytes == offset) {
1816                 if (update_stat)
1817                         unlink_free_space(ctl, left_info);
1818                 else
1819                         __unlink_free_space(ctl, left_info);
1820                 info->offset = left_info->offset;
1821                 info->bytes += left_info->bytes;
1822                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1823                 merged = true;
1824         }
1825 
1826         return merged;
1827 }
1828 
1829 int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
1830                            u64 offset, u64 bytes)
1831 {
1832         struct btrfs_free_space *info;
1833         int ret = 0;
1834 
1835         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1836         if (!info)
1837                 return -ENOMEM;
1838 
1839         info->offset = offset;
1840         info->bytes = bytes;
1841 
1842         spin_lock(&ctl->tree_lock);
1843 
1844         if (try_merge_free_space(ctl, info, true))
1845                 goto link;
1846 
1847         /*
1848          * There was no extent directly to the left or right of this new
1849          * extent then we know we're going to have to allocate a new extent, so
1850          * before we do that see if we need to drop this into a bitmap
1851          */
1852         ret = insert_into_bitmap(ctl, info);
1853         if (ret < 0) {
1854                 goto out;
1855         } else if (ret) {
1856                 ret = 0;
1857                 goto out;
1858         }
1859 link:
1860         ret = link_free_space(ctl, info);
1861         if (ret)
1862                 kmem_cache_free(btrfs_free_space_cachep, info);
1863 out:
1864         spin_unlock(&ctl->tree_lock);
1865 
1866         if (ret) {
1867                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
1868                 BUG_ON(ret == -EEXIST);
1869         }
1870 
1871         return ret;
1872 }
1873 
1874 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1875                             u64 offset, u64 bytes)
1876 {
1877         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1878         struct btrfs_free_space *info;
1879         int ret = 0;
1880 
1881         spin_lock(&ctl->tree_lock);
1882 
1883 again:
1884         if (!bytes)
1885                 goto out_lock;
1886 
1887         info = tree_search_offset(ctl, offset, 0, 0);
1888         if (!info) {
1889                 /*
1890                  * oops didn't find an extent that matched the space we wanted
1891                  * to remove, look for a bitmap instead
1892                  */
1893                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1894                                           1, 0);
1895                 if (!info) {
1896                         /* the tree logging code might be calling us before we
1897                          * have fully loaded the free space rbtree for this
1898                          * block group.  So it is possible the entry won't
1899                          * be in the rbtree yet at all.  The caching code
1900                          * will make sure not to put it in the rbtree if
1901                          * the logging code has pinned it.
1902                          */
1903                         goto out_lock;
1904                 }
1905         }
1906 
1907         if (!info->bitmap) {
1908                 unlink_free_space(ctl, info);
1909                 if (offset == info->offset) {
1910                         u64 to_free = min(bytes, info->bytes);
1911 
1912                         info->bytes -= to_free;
1913                         info->offset += to_free;
1914                         if (info->bytes) {
1915                                 ret = link_free_space(ctl, info);
1916                                 WARN_ON(ret);
1917                         } else {
1918                                 kmem_cache_free(btrfs_free_space_cachep, info);
1919                         }
1920 
1921                         offset += to_free;
1922                         bytes -= to_free;
1923                         goto again;
1924                 } else {
1925                         u64 old_end = info->bytes + info->offset;
1926 
1927                         info->bytes = offset - info->offset;
1928                         ret = link_free_space(ctl, info);
1929                         WARN_ON(ret);
1930                         if (ret)
1931                                 goto out_lock;
1932 
1933                         /* Not enough bytes in this entry to satisfy us */
1934                         if (old_end < offset + bytes) {
1935                                 bytes -= old_end - offset;
1936                                 offset = old_end;
1937                                 goto again;
1938                         } else if (old_end == offset + bytes) {
1939                                 /* all done */
1940                                 goto out_lock;
1941                         }
1942                         spin_unlock(&ctl->tree_lock);
1943 
1944                         ret = btrfs_add_free_space(block_group, offset + bytes,
1945                                                    old_end - (offset + bytes));
1946                         WARN_ON(ret);
1947                         goto out;
1948                 }
1949         }
1950 
1951         ret = remove_from_bitmap(ctl, info, &offset, &bytes);
1952         if (ret == -EAGAIN)
1953                 goto again;
1954         BUG_ON(ret); /* logic error */
1955 out_lock:
1956         spin_unlock(&ctl->tree_lock);
1957 out:
1958         return ret;
1959 }
1960 
1961 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
1962                            u64 bytes)
1963 {
1964         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1965         struct btrfs_free_space *info;
1966         struct rb_node *n;
1967         int count = 0;
1968 
1969         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
1970                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1971                 if (info->bytes >= bytes)
1972                         count++;
1973                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
1974                        (unsigned long long)info->offset,
1975                        (unsigned long long)info->bytes,
1976                        (info->bitmap) ? "yes" : "no");
1977         }
1978         printk(KERN_INFO "block group has cluster?: %s\n",
1979                list_empty(&block_group->cluster_list) ? "no" : "yes");
1980         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
1981                "\n", count);
1982 }
1983 
1984 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
1985 {
1986         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1987 
1988         spin_lock_init(&ctl->tree_lock);
1989         ctl->unit = block_group->sectorsize;
1990         ctl->start = block_group->key.objectid;
1991         ctl->private = block_group;
1992         ctl->op = &free_space_op;
1993 
1994         /*
1995          * we only want to have 32k of ram per block group for keeping
1996          * track of free space, and if we pass 1/2 of that we want to
1997          * start converting things over to using bitmaps
1998          */
1999         ctl->extents_thresh = ((1024 * 32) / 2) /
2000                                 sizeof(struct btrfs_free_space);
2001 }
2002 
2003 /*
2004  * for a given cluster, put all of its extents back into the free
2005  * space cache.  If the block group passed doesn't match the block group
2006  * pointed to by the cluster, someone else raced in and freed the
2007  * cluster already.  In that case, we just return without changing anything
2008  */
2009 static int
2010 __btrfs_return_cluster_to_free_space(
2011                              struct btrfs_block_group_cache *block_group,
2012                              struct btrfs_free_cluster *cluster)
2013 {
2014         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2015         struct btrfs_free_space *entry;
2016         struct rb_node *node;
2017 
2018         spin_lock(&cluster->lock);
2019         if (cluster->block_group != block_group)
2020                 goto out;
2021 
2022         cluster->block_group = NULL;
2023         cluster->window_start = 0;
2024         list_del_init(&cluster->block_group_list);
2025 
2026         node = rb_first(&cluster->root);
2027         while (node) {
2028                 bool bitmap;
2029 
2030                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2031                 node = rb_next(&entry->offset_index);
2032                 rb_erase(&entry->offset_index, &cluster->root);
2033 
2034                 bitmap = (entry->bitmap != NULL);
2035                 if (!bitmap)
2036                         try_merge_free_space(ctl, entry, false);
2037                 tree_insert_offset(&ctl->free_space_offset,
2038                                    entry->offset, &entry->offset_index, bitmap);
2039         }
2040         cluster->root = RB_ROOT;
2041 
2042 out:
2043         spin_unlock(&cluster->lock);
2044         btrfs_put_block_group(block_group);
2045         return 0;
2046 }
2047 
2048 void __btrfs_remove_free_space_cache_locked(struct btrfs_free_space_ctl *ctl)
2049 {
2050         struct btrfs_free_space *info;
2051         struct rb_node *node;
2052 
2053         while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
2054                 info = rb_entry(node, struct btrfs_free_space, offset_index);
2055                 if (!info->bitmap) {
2056                         unlink_free_space(ctl, info);
2057                         kmem_cache_free(btrfs_free_space_cachep, info);
2058                 } else {
2059                         free_bitmap(ctl, info);
2060                 }
2061                 if (need_resched()) {
2062                         spin_unlock(&ctl->tree_lock);
2063                         cond_resched();
2064                         spin_lock(&ctl->tree_lock);
2065                 }
2066         }
2067 }
2068 
2069 void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
2070 {
2071         spin_lock(&ctl->tree_lock);
2072         __btrfs_remove_free_space_cache_locked(ctl);
2073         spin_unlock(&ctl->tree_lock);
2074 }
2075 
2076 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
2077 {
2078         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2079         struct btrfs_free_cluster *cluster;
2080         struct list_head *head;
2081 
2082         spin_lock(&ctl->tree_lock);
2083         while ((head = block_group->cluster_list.next) !=
2084                &block_group->cluster_list) {
2085                 cluster = list_entry(head, struct btrfs_free_cluster,
2086                                      block_group_list);
2087 
2088                 WARN_ON(cluster->block_group != block_group);
2089                 __btrfs_return_cluster_to_free_space(block_group, cluster);
2090                 if (need_resched()) {
2091                         spin_unlock(&ctl->tree_lock);
2092                         cond_resched();
2093                         spin_lock(&ctl->tree_lock);
2094                 }
2095         }
2096         __btrfs_remove_free_space_cache_locked(ctl);
2097         spin_unlock(&ctl->tree_lock);
2098 
2099 }
2100 
2101 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
2102                                u64 offset, u64 bytes, u64 empty_size)
2103 {
2104         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2105         struct btrfs_free_space *entry = NULL;
2106         u64 bytes_search = bytes + empty_size;
2107         u64 ret = 0;
2108 
2109         spin_lock(&ctl->tree_lock);
2110         entry = find_free_space(ctl, &offset, &bytes_search);
2111         if (!entry)
2112                 goto out;
2113 
2114         ret = offset;
2115         if (entry->bitmap) {
2116                 bitmap_clear_bits(ctl, entry, offset, bytes);
2117                 if (!entry->bytes)
2118                         free_bitmap(ctl, entry);
2119         } else {
2120                 unlink_free_space(ctl, entry);
2121                 entry->offset += bytes;
2122                 entry->bytes -= bytes;
2123                 if (!entry->bytes)
2124                         kmem_cache_free(btrfs_free_space_cachep, entry);
2125                 else
2126                         link_free_space(ctl, entry);
2127         }
2128 
2129 out:
2130         spin_unlock(&ctl->tree_lock);
2131 
2132         return ret;
2133 }
2134 
2135 /*
2136  * given a cluster, put all of its extents back into the free space
2137  * cache.  If a block group is passed, this function will only free
2138  * a cluster that belongs to the passed block group.
2139  *
2140  * Otherwise, it'll get a reference on the block group pointed to by the
2141  * cluster and remove the cluster from it.
2142  */
2143 int btrfs_return_cluster_to_free_space(
2144                                struct btrfs_block_group_cache *block_group,
2145                                struct btrfs_free_cluster *cluster)
2146 {
2147         struct btrfs_free_space_ctl *ctl;
2148         int ret;
2149 
2150         /* first, get a safe pointer to the block group */
2151         spin_lock(&cluster->lock);
2152         if (!block_group) {
2153                 block_group = cluster->block_group;
2154                 if (!block_group) {
2155                         spin_unlock(&cluster->lock);
2156                         return 0;
2157                 }
2158         } else if (cluster->block_group != block_group) {
2159                 /* someone else has already freed it don't redo their work */
2160                 spin_unlock(&cluster->lock);
2161                 return 0;
2162         }
2163         atomic_inc(&block_group->count);
2164         spin_unlock(&cluster->lock);
2165 
2166         ctl = block_group->free_space_ctl;
2167 
2168         /* now return any extents the cluster had on it */
2169         spin_lock(&ctl->tree_lock);
2170         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
2171         spin_unlock(&ctl->tree_lock);
2172 
2173         /* finally drop our ref */
2174         btrfs_put_block_group(block_group);
2175         return ret;
2176 }
2177 
2178 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
2179                                    struct btrfs_free_cluster *cluster,
2180                                    struct btrfs_free_space *entry,
2181                                    u64 bytes, u64 min_start)
2182 {
2183         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2184         int err;
2185         u64 search_start = cluster->window_start;
2186         u64 search_bytes = bytes;
2187         u64 ret = 0;
2188 
2189         search_start = min_start;
2190         search_bytes = bytes;
2191 
2192         err = search_bitmap(ctl, entry, &search_start, &search_bytes);
2193         if (err)
2194                 return 0;
2195 
2196         ret = search_start;
2197         __bitmap_clear_bits(ctl, entry, ret, bytes);
2198 
2199         return ret;
2200 }
2201 
2202 /*
2203  * given a cluster, try to allocate 'bytes' from it, returns 0
2204  * if it couldn't find anything suitably large, or a logical disk offset
2205  * if things worked out
2206  */
2207 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
2208                              struct btrfs_free_cluster *cluster, u64 bytes,
2209                              u64 min_start)
2210 {
2211         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2212         struct btrfs_free_space *entry = NULL;
2213         struct rb_node *node;
2214         u64 ret = 0;
2215 
2216         spin_lock(&cluster->lock);
2217         if (bytes > cluster->max_size)
2218                 goto out;
2219 
2220         if (cluster->block_group != block_group)
2221                 goto out;
2222 
2223         node = rb_first(&cluster->root);
2224         if (!node)
2225                 goto out;
2226 
2227         entry = rb_entry(node, struct btrfs_free_space, offset_index);
2228         while(1) {
2229                 if (entry->bytes < bytes ||
2230                     (!entry->bitmap && entry->offset < min_start)) {
2231                         node = rb_next(&entry->offset_index);
2232                         if (!node)
2233                                 break;
2234                         entry = rb_entry(node, struct btrfs_free_space,
2235                                          offset_index);
2236                         continue;
2237                 }
2238 
2239                 if (entry->bitmap) {
2240                         ret = btrfs_alloc_from_bitmap(block_group,
2241                                                       cluster, entry, bytes,
2242                                                       cluster->window_start);
2243                         if (ret == 0) {
2244                                 node = rb_next(&entry->offset_index);
2245                                 if (!node)
2246                                         break;
2247                                 entry = rb_entry(node, struct btrfs_free_space,
2248                                                  offset_index);
2249                                 continue;
2250                         }
2251                         cluster->window_start += bytes;
2252                 } else {
2253                         ret = entry->offset;
2254 
2255                         entry->offset += bytes;
2256                         entry->bytes -= bytes;
2257                 }
2258 
2259                 if (entry->bytes == 0)
2260                         rb_erase(&entry->offset_index, &cluster->root);
2261                 break;
2262         }
2263 out:
2264         spin_unlock(&cluster->lock);
2265 
2266         if (!ret)
2267                 return 0;
2268 
2269         spin_lock(&ctl->tree_lock);
2270 
2271         ctl->free_space -= bytes;
2272         if (entry->bytes == 0) {
2273                 ctl->free_extents--;
2274                 if (entry->bitmap) {
2275                         kfree(entry->bitmap);
2276                         ctl->total_bitmaps--;
2277                         ctl->op->recalc_thresholds(ctl);
2278                 }
2279                 kmem_cache_free(btrfs_free_space_cachep, entry);
2280         }
2281 
2282         spin_unlock(&ctl->tree_lock);
2283 
2284         return ret;
2285 }
2286 
2287 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2288                                 struct btrfs_free_space *entry,
2289                                 struct btrfs_free_cluster *cluster,
2290                                 u64 offset, u64 bytes,
2291                                 u64 cont1_bytes, u64 min_bytes)
2292 {
2293         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2294         unsigned long next_zero;
2295         unsigned long i;
2296         unsigned long want_bits;
2297         unsigned long min_bits;
2298         unsigned long found_bits;
2299         unsigned long start = 0;
2300         unsigned long total_found = 0;
2301         int ret;
2302 
2303         i = offset_to_bit(entry->offset, block_group->sectorsize,
2304                           max_t(u64, offset, entry->offset));
2305         want_bits = bytes_to_bits(bytes, block_group->sectorsize);
2306         min_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
2307 
2308 again:
2309         found_bits = 0;
2310         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
2311              i < BITS_PER_BITMAP;
2312              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
2313                 next_zero = find_next_zero_bit(entry->bitmap,
2314                                                BITS_PER_BITMAP, i);
2315                 if (next_zero - i >= min_bits) {
2316                         found_bits = next_zero - i;
2317                         break;
2318                 }
2319                 i = next_zero;
2320         }
2321 
2322         if (!found_bits)
2323                 return -ENOSPC;
2324 
2325         if (!total_found) {
2326                 start = i;
2327                 cluster->max_size = 0;
2328         }
2329 
2330         total_found += found_bits;
2331 
2332         if (cluster->max_size < found_bits * block_group->sectorsize)
2333                 cluster->max_size = found_bits * block_group->sectorsize;
2334 
2335         if (total_found < want_bits || cluster->max_size < cont1_bytes) {
2336                 i = next_zero + 1;
2337                 goto again;
2338         }
2339 
2340         cluster->window_start = start * block_group->sectorsize +
2341                 entry->offset;
2342         rb_erase(&entry->offset_index, &ctl->free_space_offset);
2343         ret = tree_insert_offset(&cluster->root, entry->offset,
2344                                  &entry->offset_index, 1);
2345         BUG_ON(ret); /* -EEXIST; Logic error */
2346 
2347         trace_btrfs_setup_cluster(block_group, cluster,
2348                                   total_found * block_group->sectorsize, 1);
2349         return 0;
2350 }
2351 
2352 /*
2353  * This searches the block group for just extents to fill the cluster with.
2354  * Try to find a cluster with at least bytes total bytes, at least one
2355  * extent of cont1_bytes, and other clusters of at least min_bytes.
2356  */
2357 static noinline int
2358 setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2359                         struct btrfs_free_cluster *cluster,
2360                         struct list_head *bitmaps, u64 offset, u64 bytes,
2361                         u64 cont1_bytes, u64 min_bytes)
2362 {
2363         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2364         struct btrfs_free_space *first = NULL;
2365         struct btrfs_free_space *entry = NULL;
2366         struct btrfs_free_space *last;
2367         struct rb_node *node;
2368         u64 window_start;
2369         u64 window_free;
2370         u64 max_extent;
2371         u64 total_size = 0;
2372 
2373         entry = tree_search_offset(ctl, offset, 0, 1);
2374         if (!entry)
2375                 return -ENOSPC;
2376 
2377         /*
2378          * We don't want bitmaps, so just move along until we find a normal
2379          * extent entry.
2380          */
2381         while (entry->bitmap || entry->bytes < min_bytes) {
2382                 if (entry->bitmap && list_empty(&entry->list))
2383                         list_add_tail(&entry->list, bitmaps);
2384                 node = rb_next(&entry->offset_index);
2385                 if (!node)
2386                         return -ENOSPC;
2387                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2388         }
2389 
2390         window_start = entry->offset;
2391         window_free = entry->bytes;
2392         max_extent = entry->bytes;
2393         first = entry;
2394         last = entry;
2395 
2396         for (node = rb_next(&entry->offset_index); node;
2397              node = rb_next(&entry->offset_index)) {
2398                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2399 
2400                 if (entry->bitmap) {
2401                         if (list_empty(&entry->list))
2402                                 list_add_tail(&entry->list, bitmaps);
2403                         continue;
2404                 }
2405 
2406                 if (entry->bytes < min_bytes)
2407                         continue;
2408 
2409                 last = entry;
2410                 window_free += entry->bytes;
2411                 if (entry->bytes > max_extent)
2412                         max_extent = entry->bytes;
2413         }
2414 
2415         if (window_free < bytes || max_extent < cont1_bytes)
2416                 return -ENOSPC;
2417 
2418         cluster->window_start = first->offset;
2419 
2420         node = &first->offset_index;
2421 
2422         /*
2423          * now we've found our entries, pull them out of the free space
2424          * cache and put them into the cluster rbtree
2425          */
2426         do {
2427                 int ret;
2428 
2429                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2430                 node = rb_next(&entry->offset_index);
2431                 if (entry->bitmap || entry->bytes < min_bytes)
2432                         continue;
2433 
2434                 rb_erase(&entry->offset_index, &ctl->free_space_offset);
2435                 ret = tree_insert_offset(&cluster->root, entry->offset,
2436                                          &entry->offset_index, 0);
2437                 total_size += entry->bytes;
2438                 BUG_ON(ret); /* -EEXIST; Logic error */
2439         } while (node && entry != last);
2440 
2441         cluster->max_size = max_extent;
2442         trace_btrfs_setup_cluster(block_group, cluster, total_size, 0);
2443         return 0;
2444 }
2445 
2446 /*
2447  * This specifically looks for bitmaps that may work in the cluster, we assume
2448  * that we have already failed to find extents that will work.
2449  */
2450 static noinline int
2451 setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2452                      struct btrfs_free_cluster *cluster,
2453                      struct list_head *bitmaps, u64 offset, u64 bytes,
2454                      u64 cont1_bytes, u64 min_bytes)
2455 {
2456         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2457         struct btrfs_free_space *entry;
2458         int ret = -ENOSPC;
2459         u64 bitmap_offset = offset_to_bitmap(ctl, offset);
2460 
2461         if (ctl->total_bitmaps == 0)
2462                 return -ENOSPC;
2463 
2464         /*
2465          * The bitmap that covers offset won't be in the list unless offset
2466          * is just its start offset.
2467          */
2468         entry = list_first_entry(bitmaps, struct btrfs_free_space, list);
2469         if (entry->offset != bitmap_offset) {
2470                 entry = tree_search_offset(ctl, bitmap_offset, 1, 0);
2471                 if (entry && list_empty(&entry->list))
2472                         list_add(&entry->list, bitmaps);
2473         }
2474 
2475         list_for_each_entry(entry, bitmaps, list) {
2476                 if (entry->bytes < bytes)
2477                         continue;
2478                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2479                                            bytes, cont1_bytes, min_bytes);
2480                 if (!ret)
2481                         return 0;
2482         }
2483 
2484         /*
2485          * The bitmaps list has all the bitmaps that record free space
2486          * starting after offset, so no more search is required.
2487          */
2488         return -ENOSPC;
2489 }
2490 
2491 /*
2492  * here we try to find a cluster of blocks in a block group.  The goal
2493  * is to find at least bytes+empty_size.
2494  * We might not find them all in one contiguous area.
2495  *
2496  * returns zero and sets up cluster if things worked out, otherwise
2497  * it returns -enospc
2498  */
2499 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
2500                              struct btrfs_root *root,
2501                              struct btrfs_block_group_cache *block_group,
2502                              struct btrfs_free_cluster *cluster,
2503                              u64 offset, u64 bytes, u64 empty_size)
2504 {
2505         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2506         struct btrfs_free_space *entry, *tmp;
2507         LIST_HEAD(bitmaps);
2508         u64 min_bytes;
2509         u64 cont1_bytes;
2510         int ret;
2511 
2512         /*
2513          * Choose the minimum extent size we'll require for this
2514          * cluster.  For SSD_SPREAD, don't allow any fragmentation.
2515          * For metadata, allow allocates with smaller extents.  For
2516          * data, keep it dense.
2517          */
2518         if (btrfs_test_opt(root, SSD_SPREAD)) {
2519                 cont1_bytes = min_bytes = bytes + empty_size;
2520         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
2521                 cont1_bytes = bytes;
2522                 min_bytes = block_group->sectorsize;
2523         } else {
2524                 cont1_bytes = max(bytes, (bytes + empty_size) >> 2);
2525                 min_bytes = block_group->sectorsize;
2526         }
2527 
2528         spin_lock(&ctl->tree_lock);
2529 
2530         /*
2531          * If we know we don't have enough space to make a cluster don't even
2532          * bother doing all the work to try and find one.
2533          */
2534         if (ctl->free_space < bytes) {
2535                 spin_unlock(&ctl->tree_lock);
2536                 return -ENOSPC;
2537         }
2538 
2539         spin_lock(&cluster->lock);
2540 
2541         /* someone already found a cluster, hooray */
2542         if (cluster->block_group) {
2543                 ret = 0;
2544                 goto out;
2545         }
2546 
2547         trace_btrfs_find_cluster(block_group, offset, bytes, empty_size,
2548                                  min_bytes);
2549 
2550         INIT_LIST_HEAD(&bitmaps);
2551         ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
2552                                       bytes + empty_size,
2553                                       cont1_bytes, min_bytes);
2554         if (ret)
2555                 ret = setup_cluster_bitmap(block_group, cluster, &bitmaps,
2556                                            offset, bytes + empty_size,
2557                                            cont1_bytes, min_bytes);
2558 
2559         /* Clear our temporary list */
2560         list_for_each_entry_safe(entry, tmp, &bitmaps, list)
2561                 list_del_init(&entry->list);
2562 
2563         if (!ret) {
2564                 atomic_inc(&block_group->count);
2565                 list_add_tail(&cluster->block_group_list,
2566                               &block_group->cluster_list);
2567                 cluster->block_group = block_group;
2568         } else {
2569                 trace_btrfs_failed_cluster_setup(block_group);
2570         }
2571 out:
2572         spin_unlock(&cluster->lock);
2573         spin_unlock(&ctl->tree_lock);
2574 
2575         return ret;
2576 }
2577 
2578 /*
2579  * simple code to zero out a cluster
2580  */
2581 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2582 {
2583         spin_lock_init(&cluster->lock);
2584         spin_lock_init(&cluster->refill_lock);
2585         cluster->root = RB_ROOT;
2586         cluster->max_size = 0;
2587         INIT_LIST_HEAD(&cluster->block_group_list);
2588         cluster->block_group = NULL;
2589 }
2590 
2591 static int do_trimming(struct btrfs_block_group_cache *block_group,
2592                        u64 *total_trimmed, u64 start, u64 bytes,
2593                        u64 reserved_start, u64 reserved_bytes)
2594 {
2595         struct btrfs_space_info *space_info = block_group->space_info;
2596         struct btrfs_fs_info *fs_info = block_group->fs_info;
2597         int ret;
2598         int update = 0;
2599         u64 trimmed = 0;
2600 
2601         spin_lock(&space_info->lock);
2602         spin_lock(&block_group->lock);
2603         if (!block_group->ro) {
2604                 block_group->reserved += reserved_bytes;
2605                 space_info->bytes_reserved += reserved_bytes;
2606                 update = 1;
2607         }
2608         spin_unlock(&block_group->lock);
2609         spin_unlock(&space_info->lock);
2610 
2611         ret = btrfs_error_discard_extent(fs_info->extent_root,
2612                                          start, bytes, &trimmed);
2613         if (!ret)
2614                 *total_trimmed += trimmed;
2615 
2616         btrfs_add_free_space(block_group, reserved_start, reserved_bytes);
2617 
2618         if (update) {
2619                 spin_lock(&space_info->lock);
2620                 spin_lock(&block_group->lock);
2621                 if (block_group->ro)
2622                         space_info->bytes_readonly += reserved_bytes;
2623                 block_group->reserved -= reserved_bytes;
2624                 space_info->bytes_reserved -= reserved_bytes;
2625                 spin_unlock(&space_info->lock);
2626                 spin_unlock(&block_group->lock);
2627         }
2628 
2629         return ret;
2630 }
2631 
2632 static int trim_no_bitmap(struct btrfs_block_group_cache *block_group,
2633                           u64 *total_trimmed, u64 start, u64 end, u64 minlen)
2634 {
2635         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2636         struct btrfs_free_space *entry;
2637         struct rb_node *node;
2638         int ret = 0;
2639         u64 extent_start;
2640         u64 extent_bytes;
2641         u64 bytes;
2642 
2643         while (start < end) {
2644                 spin_lock(&ctl->tree_lock);
2645 
2646                 if (ctl->free_space < minlen) {
2647                         spin_unlock(&ctl->tree_lock);
2648                         break;
2649                 }
2650 
2651                 entry = tree_search_offset(ctl, start, 0, 1);
2652                 if (!entry) {
2653                         spin_unlock(&ctl->tree_lock);
2654                         break;
2655                 }
2656 
2657                 /* skip bitmaps */
2658                 while (entry->bitmap) {
2659                         node = rb_next(&entry->offset_index);
2660                         if (!node) {
2661                                 spin_unlock(&ctl->tree_lock);
2662                                 goto out;
2663                         }
2664                         entry = rb_entry(node, struct btrfs_free_space,
2665                                          offset_index);
2666                 }
2667 
2668                 if (entry->offset >= end) {
2669                         spin_unlock(&ctl->tree_lock);
2670                         break;
2671                 }
2672 
2673                 extent_start = entry->offset;
2674                 extent_bytes = entry->bytes;
2675                 start = max(start, extent_start);
2676                 bytes = min(extent_start + extent_bytes, end) - start;
2677                 if (bytes < minlen) {
2678                         spin_unlock(&ctl->tree_lock);
2679                         goto next;
2680                 }
2681 
2682                 unlink_free_space(ctl, entry);
2683                 kmem_cache_free(btrfs_free_space_cachep, entry);
2684 
2685                 spin_unlock(&ctl->tree_lock);
2686 
2687                 ret = do_trimming(block_group, total_trimmed, start, bytes,
2688                                   extent_start, extent_bytes);
2689                 if (ret)
2690                         break;
2691 next:
2692                 start += bytes;
2693 
2694                 if (fatal_signal_pending(current)) {
2695                         ret = -ERESTARTSYS;
2696                         break;
2697                 }
2698 
2699                 cond_resched();
2700         }
2701 out:
2702         return ret;
2703 }
2704 
2705 static int trim_bitmaps(struct btrfs_block_group_cache *block_group,
2706                         u64 *total_trimmed, u64 start, u64 end, u64 minlen)
2707 {
2708         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2709         struct btrfs_free_space *entry;
2710         int ret = 0;
2711         int ret2;
2712         u64 bytes;
2713         u64 offset = offset_to_bitmap(ctl, start);
2714 
2715         while (offset < end) {
2716                 bool next_bitmap = false;
2717 
2718                 spin_lock(&ctl->tree_lock);
2719 
2720                 if (ctl->free_space < minlen) {
2721                         spin_unlock(&ctl->tree_lock);
2722                         break;
2723                 }
2724 
2725                 entry = tree_search_offset(ctl, offset, 1, 0);
2726                 if (!entry) {
2727                         spin_unlock(&ctl->tree_lock);
2728                         next_bitmap = true;
2729                         goto next;
2730                 }
2731 
2732                 bytes = minlen;
2733                 ret2 = search_bitmap(ctl, entry, &start, &bytes);
2734                 if (ret2 || start >= end) {
2735                         spin_unlock(&ctl->tree_lock);
2736                         next_bitmap = true;
2737                         goto next;
2738                 }
2739 
2740                 bytes = min(bytes, end - start);
2741                 if (bytes < minlen) {
2742                         spin_unlock(&ctl->tree_lock);
2743                         goto next;
2744                 }
2745 
2746                 bitmap_clear_bits(ctl, entry, start, bytes);
2747                 if (entry->bytes == 0)
2748                         free_bitmap(ctl, entry);
2749 
2750                 spin_unlock(&ctl->tree_lock);
2751 
2752                 ret = do_trimming(block_group, total_trimmed, start, bytes,
2753                                   start, bytes);
2754                 if (ret)
2755                         break;
2756 next:
2757                 if (next_bitmap) {
2758                         offset += BITS_PER_BITMAP * ctl->unit;
2759                 } else {
2760                         start += bytes;
2761                         if (start >= offset + BITS_PER_BITMAP * ctl->unit)
2762                                 offset += BITS_PER_BITMAP * ctl->unit;
2763                 }
2764 
2765                 if (fatal_signal_pending(current)) {
2766                         ret = -ERESTARTSYS;
2767                         break;
2768                 }
2769 
2770                 cond_resched();
2771         }
2772 
2773         return ret;
2774 }
2775 
2776 int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
2777                            u64 *trimmed, u64 start, u64 end, u64 minlen)
2778 {
2779         int ret;
2780 
2781         *trimmed = 0;
2782 
2783         ret = trim_no_bitmap(block_group, trimmed, start, end, minlen);
2784         if (ret)
2785                 return ret;
2786 
2787         ret = trim_bitmaps(block_group, trimmed, start, end, minlen);
2788 
2789         return ret;
2790 }
2791 
2792 /*
2793  * Find the left-most item in the cache tree, and then return the
2794  * smallest inode number in the item.
2795  *
2796  * Note: the returned inode number may not be the smallest one in
2797  * the tree, if the left-most item is a bitmap.
2798  */
2799 u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
2800 {
2801         struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
2802         struct btrfs_free_space *entry = NULL;
2803         u64 ino = 0;
2804 
2805         spin_lock(&ctl->tree_lock);
2806 
2807         if (RB_EMPTY_ROOT(&ctl->free_space_offset))
2808                 goto out;
2809 
2810         entry = rb_entry(rb_first(&ctl->free_space_offset),
2811                          struct btrfs_free_space, offset_index);
2812 
2813         if (!entry->bitmap) {
2814                 ino = entry->offset;
2815 
2816                 unlink_free_space(ctl, entry);
2817                 entry->offset++;
2818                 entry->bytes--;
2819                 if (!entry->bytes)
2820                         kmem_cache_free(btrfs_free_space_cachep, entry);
2821                 else
2822                         link_free_space(ctl, entry);
2823         } else {
2824                 u64 offset = 0;
2825                 u64 count = 1;
2826                 int ret;
2827 
2828                 ret = search_bitmap(ctl, entry, &offset, &count);
2829                 /* Logic error; Should be empty if it can't find anything */
2830                 BUG_ON(ret);
2831 
2832                 ino = offset;
2833                 bitmap_clear_bits(ctl, entry, offset, 1);
2834                 if (entry->bytes == 0)
2835                         free_bitmap(ctl, entry);
2836         }
2837 out:
2838         spin_unlock(&ctl->tree_lock);
2839 
2840         return ino;
2841 }
2842 
2843 struct inode *lookup_free_ino_inode(struct btrfs_root *root,
2844                                     struct btrfs_path *path)
2845 {
2846         struct inode *inode = NULL;
2847 
2848         spin_lock(&root->cache_lock);
2849         if (root->cache_inode)
2850                 inode = igrab(root->cache_inode);
2851         spin_unlock(&root->cache_lock);
2852         if (inode)
2853                 return inode;
2854 
2855         inode = __lookup_free_space_inode(root, path, 0);
2856         if (IS_ERR(inode))
2857                 return inode;
2858 
2859         spin_lock(&root->cache_lock);
2860         if (!btrfs_fs_closing(root->fs_info))
2861                 root->cache_inode = igrab(inode);
2862         spin_unlock(&root->cache_lock);
2863 
2864         return inode;
2865 }
2866 
2867 int create_free_ino_inode(struct btrfs_root *root,
2868                           struct btrfs_trans_handle *trans,
2869                           struct btrfs_path *path)
2870 {
2871         return __create_free_space_inode(root, trans, path,
2872                                          BTRFS_FREE_INO_OBJECTID, 0);
2873 }
2874 
2875 int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
2876 {
2877         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2878         struct btrfs_path *path;
2879         struct inode *inode;
2880         int ret = 0;
2881         u64 root_gen = btrfs_root_generation(&root->root_item);
2882 
2883         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2884                 return 0;
2885 
2886         /*
2887          * If we're unmounting then just return, since this does a search on the
2888          * normal root and not the commit root and we could deadlock.
2889          */
2890         if (btrfs_fs_closing(fs_info))
2891                 return 0;
2892 
2893         path = btrfs_alloc_path();
2894         if (!path)
2895                 return 0;
2896 
2897         inode = lookup_free_ino_inode(root, path);
2898         if (IS_ERR(inode))
2899                 goto out;
2900 
2901         if (root_gen != BTRFS_I(inode)->generation)
2902                 goto out_put;
2903 
2904         ret = __load_free_space_cache(root, inode, ctl, path, 0);
2905 
2906         if (ret < 0)
2907                 printk(KERN_ERR "btrfs: failed to load free ino cache for "
2908                        "root %llu\n", root->root_key.objectid);
2909 out_put:
2910         iput(inode);
2911 out:
2912         btrfs_free_path(path);
2913         return ret;
2914 }
2915 
2916 int btrfs_write_out_ino_cache(struct btrfs_root *root,
2917                               struct btrfs_trans_handle *trans,
2918                               struct btrfs_path *path)
2919 {
2920         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2921         struct inode *inode;
2922         int ret;
2923 
2924         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2925                 return 0;
2926 
2927         inode = lookup_free_ino_inode(root, path);
2928         if (IS_ERR(inode))
2929                 return 0;
2930 
2931         ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
2932         if (ret) {
2933                 btrfs_delalloc_release_metadata(inode, inode->i_size);
2934 #ifdef DEBUG
2935                 printk(KERN_ERR "btrfs: failed to write free ino cache "
2936                        "for root %llu\n", root->root_key.objectid);
2937 #endif
2938         }
2939 
2940         iput(inode);
2941         return ret;
2942 }
2943 

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