Btrfs: use the commit_root for reading free_space_inode crcs
[pandora-kernel.git] / fs / btrfs / file-item.c
1 /*
2  * Copyright (C) 2007 Oracle.  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/bio.h>
20 #include <linux/slab.h>
21 #include <linux/pagemap.h>
22 #include <linux/highmem.h>
23 #include "ctree.h"
24 #include "disk-io.h"
25 #include "transaction.h"
26 #include "print-tree.h"
27
28 #define MAX_CSUM_ITEMS(r, size) ((((BTRFS_LEAF_DATA_SIZE(r) - \
29                                    sizeof(struct btrfs_item) * 2) / \
30                                   size) - 1))
31
32 #define MAX_ORDERED_SUM_BYTES(r) ((PAGE_SIZE - \
33                                    sizeof(struct btrfs_ordered_sum)) / \
34                                    sizeof(struct btrfs_sector_sum) * \
35                                    (r)->sectorsize - (r)->sectorsize)
36
37 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
38                              struct btrfs_root *root,
39                              u64 objectid, u64 pos,
40                              u64 disk_offset, u64 disk_num_bytes,
41                              u64 num_bytes, u64 offset, u64 ram_bytes,
42                              u8 compression, u8 encryption, u16 other_encoding)
43 {
44         int ret = 0;
45         struct btrfs_file_extent_item *item;
46         struct btrfs_key file_key;
47         struct btrfs_path *path;
48         struct extent_buffer *leaf;
49
50         path = btrfs_alloc_path();
51         if (!path)
52                 return -ENOMEM;
53         file_key.objectid = objectid;
54         file_key.offset = pos;
55         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
56
57         path->leave_spinning = 1;
58         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
59                                       sizeof(*item));
60         if (ret < 0)
61                 goto out;
62         BUG_ON(ret);
63         leaf = path->nodes[0];
64         item = btrfs_item_ptr(leaf, path->slots[0],
65                               struct btrfs_file_extent_item);
66         btrfs_set_file_extent_disk_bytenr(leaf, item, disk_offset);
67         btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
68         btrfs_set_file_extent_offset(leaf, item, offset);
69         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
70         btrfs_set_file_extent_ram_bytes(leaf, item, ram_bytes);
71         btrfs_set_file_extent_generation(leaf, item, trans->transid);
72         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
73         btrfs_set_file_extent_compression(leaf, item, compression);
74         btrfs_set_file_extent_encryption(leaf, item, encryption);
75         btrfs_set_file_extent_other_encoding(leaf, item, other_encoding);
76
77         btrfs_mark_buffer_dirty(leaf);
78 out:
79         btrfs_free_path(path);
80         return ret;
81 }
82
83 struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
84                                           struct btrfs_root *root,
85                                           struct btrfs_path *path,
86                                           u64 bytenr, int cow)
87 {
88         int ret;
89         struct btrfs_key file_key;
90         struct btrfs_key found_key;
91         struct btrfs_csum_item *item;
92         struct extent_buffer *leaf;
93         u64 csum_offset = 0;
94         u16 csum_size =
95                 btrfs_super_csum_size(&root->fs_info->super_copy);
96         int csums_in_item;
97
98         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
99         file_key.offset = bytenr;
100         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
101         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
102         if (ret < 0)
103                 goto fail;
104         leaf = path->nodes[0];
105         if (ret > 0) {
106                 ret = 1;
107                 if (path->slots[0] == 0)
108                         goto fail;
109                 path->slots[0]--;
110                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
111                 if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY)
112                         goto fail;
113
114                 csum_offset = (bytenr - found_key.offset) >>
115                                 root->fs_info->sb->s_blocksize_bits;
116                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
117                 csums_in_item /= csum_size;
118
119                 if (csum_offset >= csums_in_item) {
120                         ret = -EFBIG;
121                         goto fail;
122                 }
123         }
124         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
125         item = (struct btrfs_csum_item *)((unsigned char *)item +
126                                           csum_offset * csum_size);
127         return item;
128 fail:
129         if (ret > 0)
130                 ret = -ENOENT;
131         return ERR_PTR(ret);
132 }
133
134
135 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
136                              struct btrfs_root *root,
137                              struct btrfs_path *path, u64 objectid,
138                              u64 offset, int mod)
139 {
140         int ret;
141         struct btrfs_key file_key;
142         int ins_len = mod < 0 ? -1 : 0;
143         int cow = mod != 0;
144
145         file_key.objectid = objectid;
146         file_key.offset = offset;
147         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
148         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
149         return ret;
150 }
151
152
153 static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
154                                    struct inode *inode, struct bio *bio,
155                                    u64 logical_offset, u32 *dst, int dio)
156 {
157         u32 sum;
158         struct bio_vec *bvec = bio->bi_io_vec;
159         int bio_index = 0;
160         u64 offset = 0;
161         u64 item_start_offset = 0;
162         u64 item_last_offset = 0;
163         u64 disk_bytenr;
164         u32 diff;
165         u16 csum_size =
166                 btrfs_super_csum_size(&root->fs_info->super_copy);
167         int ret;
168         struct btrfs_path *path;
169         struct btrfs_csum_item *item = NULL;
170         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
171
172         path = btrfs_alloc_path();
173         if (!path)
174                 return -ENOMEM;
175         if (bio->bi_size > PAGE_CACHE_SIZE * 8)
176                 path->reada = 2;
177
178         WARN_ON(bio->bi_vcnt <= 0);
179
180         /*
181          * the free space stuff is only read when it hasn't been
182          * updated in the current transaction.  So, we can safely
183          * read from the commit root and sidestep a nasty deadlock
184          * between reading the free space cache and updating the csum tree.
185          */
186         if (btrfs_is_free_space_inode(root, inode))
187                 path->search_commit_root = 1;
188
189         disk_bytenr = (u64)bio->bi_sector << 9;
190         if (dio)
191                 offset = logical_offset;
192         while (bio_index < bio->bi_vcnt) {
193                 if (!dio)
194                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
195                 ret = btrfs_find_ordered_sum(inode, offset, disk_bytenr, &sum);
196                 if (ret == 0)
197                         goto found;
198
199                 if (!item || disk_bytenr < item_start_offset ||
200                     disk_bytenr >= item_last_offset) {
201                         struct btrfs_key found_key;
202                         u32 item_size;
203
204                         if (item)
205                                 btrfs_release_path(path);
206                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
207                                                  path, disk_bytenr, 0);
208                         if (IS_ERR(item)) {
209                                 ret = PTR_ERR(item);
210                                 if (ret == -ENOENT || ret == -EFBIG)
211                                         ret = 0;
212                                 sum = 0;
213                                 if (BTRFS_I(inode)->root->root_key.objectid ==
214                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
215                                         set_extent_bits(io_tree, offset,
216                                                 offset + bvec->bv_len - 1,
217                                                 EXTENT_NODATASUM, GFP_NOFS);
218                                 } else {
219                                         printk(KERN_INFO "btrfs no csum found "
220                                                "for inode %llu start %llu\n",
221                                                (unsigned long long)
222                                                btrfs_ino(inode),
223                                                (unsigned long long)offset);
224                                 }
225                                 item = NULL;
226                                 btrfs_release_path(path);
227                                 goto found;
228                         }
229                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
230                                               path->slots[0]);
231
232                         item_start_offset = found_key.offset;
233                         item_size = btrfs_item_size_nr(path->nodes[0],
234                                                        path->slots[0]);
235                         item_last_offset = item_start_offset +
236                                 (item_size / csum_size) *
237                                 root->sectorsize;
238                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
239                                               struct btrfs_csum_item);
240                 }
241                 /*
242                  * this byte range must be able to fit inside
243                  * a single leaf so it will also fit inside a u32
244                  */
245                 diff = disk_bytenr - item_start_offset;
246                 diff = diff / root->sectorsize;
247                 diff = diff * csum_size;
248
249                 read_extent_buffer(path->nodes[0], &sum,
250                                    ((unsigned long)item) + diff,
251                                    csum_size);
252 found:
253                 if (dst)
254                         *dst++ = sum;
255                 else
256                         set_state_private(io_tree, offset, sum);
257                 disk_bytenr += bvec->bv_len;
258                 offset += bvec->bv_len;
259                 bio_index++;
260                 bvec++;
261         }
262         btrfs_free_path(path);
263         return 0;
264 }
265
266 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
267                           struct bio *bio, u32 *dst)
268 {
269         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
270 }
271
272 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
273                               struct bio *bio, u64 offset, u32 *dst)
274 {
275         return __btrfs_lookup_bio_sums(root, inode, bio, offset, dst, 1);
276 }
277
278 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
279                              struct list_head *list, int search_commit)
280 {
281         struct btrfs_key key;
282         struct btrfs_path *path;
283         struct extent_buffer *leaf;
284         struct btrfs_ordered_sum *sums;
285         struct btrfs_sector_sum *sector_sum;
286         struct btrfs_csum_item *item;
287         unsigned long offset;
288         int ret;
289         size_t size;
290         u64 csum_end;
291         u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
292
293         path = btrfs_alloc_path();
294         BUG_ON(!path);
295
296         if (search_commit) {
297                 path->skip_locking = 1;
298                 path->reada = 2;
299                 path->search_commit_root = 1;
300         }
301
302         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
303         key.offset = start;
304         key.type = BTRFS_EXTENT_CSUM_KEY;
305
306         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
307         if (ret < 0)
308                 goto fail;
309         if (ret > 0 && path->slots[0] > 0) {
310                 leaf = path->nodes[0];
311                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
312                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
313                     key.type == BTRFS_EXTENT_CSUM_KEY) {
314                         offset = (start - key.offset) >>
315                                  root->fs_info->sb->s_blocksize_bits;
316                         if (offset * csum_size <
317                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
318                                 path->slots[0]--;
319                 }
320         }
321
322         while (start <= end) {
323                 leaf = path->nodes[0];
324                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
325                         ret = btrfs_next_leaf(root, path);
326                         if (ret < 0)
327                                 goto fail;
328                         if (ret > 0)
329                                 break;
330                         leaf = path->nodes[0];
331                 }
332
333                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
334                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
335                     key.type != BTRFS_EXTENT_CSUM_KEY)
336                         break;
337
338                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
339                 if (key.offset > end)
340                         break;
341
342                 if (key.offset > start)
343                         start = key.offset;
344
345                 size = btrfs_item_size_nr(leaf, path->slots[0]);
346                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
347                 if (csum_end <= start) {
348                         path->slots[0]++;
349                         continue;
350                 }
351
352                 csum_end = min(csum_end, end + 1);
353                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
354                                       struct btrfs_csum_item);
355                 while (start < csum_end) {
356                         size = min_t(size_t, csum_end - start,
357                                         MAX_ORDERED_SUM_BYTES(root));
358                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
359                                         GFP_NOFS);
360                         BUG_ON(!sums);
361
362                         sector_sum = sums->sums;
363                         sums->bytenr = start;
364                         sums->len = size;
365
366                         offset = (start - key.offset) >>
367                                 root->fs_info->sb->s_blocksize_bits;
368                         offset *= csum_size;
369
370                         while (size > 0) {
371                                 read_extent_buffer(path->nodes[0],
372                                                 &sector_sum->sum,
373                                                 ((unsigned long)item) +
374                                                 offset, csum_size);
375                                 sector_sum->bytenr = start;
376
377                                 size -= root->sectorsize;
378                                 start += root->sectorsize;
379                                 offset += csum_size;
380                                 sector_sum++;
381                         }
382                         list_add_tail(&sums->list, list);
383                 }
384                 path->slots[0]++;
385         }
386         ret = 0;
387 fail:
388         btrfs_free_path(path);
389         return ret;
390 }
391
392 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
393                        struct bio *bio, u64 file_start, int contig)
394 {
395         struct btrfs_ordered_sum *sums;
396         struct btrfs_sector_sum *sector_sum;
397         struct btrfs_ordered_extent *ordered;
398         char *data;
399         struct bio_vec *bvec = bio->bi_io_vec;
400         int bio_index = 0;
401         unsigned long total_bytes = 0;
402         unsigned long this_sum_bytes = 0;
403         u64 offset;
404         u64 disk_bytenr;
405
406         WARN_ON(bio->bi_vcnt <= 0);
407         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
408         if (!sums)
409                 return -ENOMEM;
410
411         sector_sum = sums->sums;
412         disk_bytenr = (u64)bio->bi_sector << 9;
413         sums->len = bio->bi_size;
414         INIT_LIST_HEAD(&sums->list);
415
416         if (contig)
417                 offset = file_start;
418         else
419                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
420
421         ordered = btrfs_lookup_ordered_extent(inode, offset);
422         BUG_ON(!ordered);
423         sums->bytenr = ordered->start;
424
425         while (bio_index < bio->bi_vcnt) {
426                 if (!contig)
427                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
428
429                 if (!contig && (offset >= ordered->file_offset + ordered->len ||
430                     offset < ordered->file_offset)) {
431                         unsigned long bytes_left;
432                         sums->len = this_sum_bytes;
433                         this_sum_bytes = 0;
434                         btrfs_add_ordered_sum(inode, ordered, sums);
435                         btrfs_put_ordered_extent(ordered);
436
437                         bytes_left = bio->bi_size - total_bytes;
438
439                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
440                                        GFP_NOFS);
441                         BUG_ON(!sums);
442                         sector_sum = sums->sums;
443                         sums->len = bytes_left;
444                         ordered = btrfs_lookup_ordered_extent(inode, offset);
445                         BUG_ON(!ordered);
446                         sums->bytenr = ordered->start;
447                 }
448
449                 data = kmap_atomic(bvec->bv_page, KM_USER0);
450                 sector_sum->sum = ~(u32)0;
451                 sector_sum->sum = btrfs_csum_data(root,
452                                                   data + bvec->bv_offset,
453                                                   sector_sum->sum,
454                                                   bvec->bv_len);
455                 kunmap_atomic(data, KM_USER0);
456                 btrfs_csum_final(sector_sum->sum,
457                                  (char *)&sector_sum->sum);
458                 sector_sum->bytenr = disk_bytenr;
459
460                 sector_sum++;
461                 bio_index++;
462                 total_bytes += bvec->bv_len;
463                 this_sum_bytes += bvec->bv_len;
464                 disk_bytenr += bvec->bv_len;
465                 offset += bvec->bv_len;
466                 bvec++;
467         }
468         this_sum_bytes = 0;
469         btrfs_add_ordered_sum(inode, ordered, sums);
470         btrfs_put_ordered_extent(ordered);
471         return 0;
472 }
473
474 /*
475  * helper function for csum removal, this expects the
476  * key to describe the csum pointed to by the path, and it expects
477  * the csum to overlap the range [bytenr, len]
478  *
479  * The csum should not be entirely contained in the range and the
480  * range should not be entirely contained in the csum.
481  *
482  * This calls btrfs_truncate_item with the correct args based on the
483  * overlap, and fixes up the key as required.
484  */
485 static noinline int truncate_one_csum(struct btrfs_trans_handle *trans,
486                                       struct btrfs_root *root,
487                                       struct btrfs_path *path,
488                                       struct btrfs_key *key,
489                                       u64 bytenr, u64 len)
490 {
491         struct extent_buffer *leaf;
492         u16 csum_size =
493                 btrfs_super_csum_size(&root->fs_info->super_copy);
494         u64 csum_end;
495         u64 end_byte = bytenr + len;
496         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
497         int ret;
498
499         leaf = path->nodes[0];
500         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
501         csum_end <<= root->fs_info->sb->s_blocksize_bits;
502         csum_end += key->offset;
503
504         if (key->offset < bytenr && csum_end <= end_byte) {
505                 /*
506                  *         [ bytenr - len ]
507                  *         [   ]
508                  *   [csum     ]
509                  *   A simple truncate off the end of the item
510                  */
511                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
512                 new_size *= csum_size;
513                 ret = btrfs_truncate_item(trans, root, path, new_size, 1);
514         } else if (key->offset >= bytenr && csum_end > end_byte &&
515                    end_byte > key->offset) {
516                 /*
517                  *         [ bytenr - len ]
518                  *                 [ ]
519                  *                 [csum     ]
520                  * we need to truncate from the beginning of the csum
521                  */
522                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
523                 new_size *= csum_size;
524
525                 ret = btrfs_truncate_item(trans, root, path, new_size, 0);
526
527                 key->offset = end_byte;
528                 ret = btrfs_set_item_key_safe(trans, root, path, key);
529                 BUG_ON(ret);
530         } else {
531                 BUG();
532         }
533         return 0;
534 }
535
536 /*
537  * deletes the csum items from the csum tree for a given
538  * range of bytes.
539  */
540 int btrfs_del_csums(struct btrfs_trans_handle *trans,
541                     struct btrfs_root *root, u64 bytenr, u64 len)
542 {
543         struct btrfs_path *path;
544         struct btrfs_key key;
545         u64 end_byte = bytenr + len;
546         u64 csum_end;
547         struct extent_buffer *leaf;
548         int ret;
549         u16 csum_size =
550                 btrfs_super_csum_size(&root->fs_info->super_copy);
551         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
552
553         root = root->fs_info->csum_root;
554
555         path = btrfs_alloc_path();
556         if (!path)
557                 return -ENOMEM;
558
559         while (1) {
560                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
561                 key.offset = end_byte - 1;
562                 key.type = BTRFS_EXTENT_CSUM_KEY;
563
564                 path->leave_spinning = 1;
565                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
566                 if (ret > 0) {
567                         if (path->slots[0] == 0)
568                                 break;
569                         path->slots[0]--;
570                 } else if (ret < 0) {
571                         break;
572                 }
573
574                 leaf = path->nodes[0];
575                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
576
577                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
578                     key.type != BTRFS_EXTENT_CSUM_KEY) {
579                         break;
580                 }
581
582                 if (key.offset >= end_byte)
583                         break;
584
585                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
586                 csum_end <<= blocksize_bits;
587                 csum_end += key.offset;
588
589                 /* this csum ends before we start, we're done */
590                 if (csum_end <= bytenr)
591                         break;
592
593                 /* delete the entire item, it is inside our range */
594                 if (key.offset >= bytenr && csum_end <= end_byte) {
595                         ret = btrfs_del_item(trans, root, path);
596                         if (ret)
597                                 goto out;
598                         if (key.offset == bytenr)
599                                 break;
600                 } else if (key.offset < bytenr && csum_end > end_byte) {
601                         unsigned long offset;
602                         unsigned long shift_len;
603                         unsigned long item_offset;
604                         /*
605                          *        [ bytenr - len ]
606                          *     [csum                ]
607                          *
608                          * Our bytes are in the middle of the csum,
609                          * we need to split this item and insert a new one.
610                          *
611                          * But we can't drop the path because the
612                          * csum could change, get removed, extended etc.
613                          *
614                          * The trick here is the max size of a csum item leaves
615                          * enough room in the tree block for a single
616                          * item header.  So, we split the item in place,
617                          * adding a new header pointing to the existing
618                          * bytes.  Then we loop around again and we have
619                          * a nicely formed csum item that we can neatly
620                          * truncate.
621                          */
622                         offset = (bytenr - key.offset) >> blocksize_bits;
623                         offset *= csum_size;
624
625                         shift_len = (len >> blocksize_bits) * csum_size;
626
627                         item_offset = btrfs_item_ptr_offset(leaf,
628                                                             path->slots[0]);
629
630                         memset_extent_buffer(leaf, 0, item_offset + offset,
631                                              shift_len);
632                         key.offset = bytenr;
633
634                         /*
635                          * btrfs_split_item returns -EAGAIN when the
636                          * item changed size or key
637                          */
638                         ret = btrfs_split_item(trans, root, path, &key, offset);
639                         BUG_ON(ret && ret != -EAGAIN);
640
641                         key.offset = end_byte - 1;
642                 } else {
643                         ret = truncate_one_csum(trans, root, path,
644                                                 &key, bytenr, len);
645                         BUG_ON(ret);
646                         if (key.offset < bytenr)
647                                 break;
648                 }
649                 btrfs_release_path(path);
650         }
651         ret = 0;
652 out:
653         btrfs_free_path(path);
654         return ret;
655 }
656
657 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
658                            struct btrfs_root *root,
659                            struct btrfs_ordered_sum *sums)
660 {
661         u64 bytenr;
662         int ret;
663         struct btrfs_key file_key;
664         struct btrfs_key found_key;
665         u64 next_offset;
666         u64 total_bytes = 0;
667         int found_next;
668         struct btrfs_path *path;
669         struct btrfs_csum_item *item;
670         struct btrfs_csum_item *item_end;
671         struct extent_buffer *leaf = NULL;
672         u64 csum_offset;
673         struct btrfs_sector_sum *sector_sum;
674         u32 nritems;
675         u32 ins_size;
676         u16 csum_size =
677                 btrfs_super_csum_size(&root->fs_info->super_copy);
678
679         path = btrfs_alloc_path();
680         BUG_ON(!path);
681         sector_sum = sums->sums;
682 again:
683         next_offset = (u64)-1;
684         found_next = 0;
685         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
686         file_key.offset = sector_sum->bytenr;
687         bytenr = sector_sum->bytenr;
688         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
689
690         item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
691         if (!IS_ERR(item)) {
692                 leaf = path->nodes[0];
693                 ret = 0;
694                 goto found;
695         }
696         ret = PTR_ERR(item);
697         if (ret != -EFBIG && ret != -ENOENT)
698                 goto fail_unlock;
699
700         if (ret == -EFBIG) {
701                 u32 item_size;
702                 /* we found one, but it isn't big enough yet */
703                 leaf = path->nodes[0];
704                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
705                 if ((item_size / csum_size) >=
706                     MAX_CSUM_ITEMS(root, csum_size)) {
707                         /* already at max size, make a new one */
708                         goto insert;
709                 }
710         } else {
711                 int slot = path->slots[0] + 1;
712                 /* we didn't find a csum item, insert one */
713                 nritems = btrfs_header_nritems(path->nodes[0]);
714                 if (path->slots[0] >= nritems - 1) {
715                         ret = btrfs_next_leaf(root, path);
716                         if (ret == 1)
717                                 found_next = 1;
718                         if (ret != 0)
719                                 goto insert;
720                         slot = 0;
721                 }
722                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
723                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
724                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
725                         found_next = 1;
726                         goto insert;
727                 }
728                 next_offset = found_key.offset;
729                 found_next = 1;
730                 goto insert;
731         }
732
733         /*
734          * at this point, we know the tree has an item, but it isn't big
735          * enough yet to put our csum in.  Grow it
736          */
737         btrfs_release_path(path);
738         ret = btrfs_search_slot(trans, root, &file_key, path,
739                                 csum_size, 1);
740         if (ret < 0)
741                 goto fail_unlock;
742
743         if (ret > 0) {
744                 if (path->slots[0] == 0)
745                         goto insert;
746                 path->slots[0]--;
747         }
748
749         leaf = path->nodes[0];
750         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
751         csum_offset = (bytenr - found_key.offset) >>
752                         root->fs_info->sb->s_blocksize_bits;
753
754         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
755             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
756             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
757                 goto insert;
758         }
759
760         if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
761             csum_size) {
762                 u32 diff = (csum_offset + 1) * csum_size;
763
764                 /*
765                  * is the item big enough already?  we dropped our lock
766                  * before and need to recheck
767                  */
768                 if (diff < btrfs_item_size_nr(leaf, path->slots[0]))
769                         goto csum;
770
771                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
772                 if (diff != csum_size)
773                         goto insert;
774
775                 ret = btrfs_extend_item(trans, root, path, diff);
776                 goto csum;
777         }
778
779 insert:
780         btrfs_release_path(path);
781         csum_offset = 0;
782         if (found_next) {
783                 u64 tmp = total_bytes + root->sectorsize;
784                 u64 next_sector = sector_sum->bytenr;
785                 struct btrfs_sector_sum *next = sector_sum + 1;
786
787                 while (tmp < sums->len) {
788                         if (next_sector + root->sectorsize != next->bytenr)
789                                 break;
790                         tmp += root->sectorsize;
791                         next_sector = next->bytenr;
792                         next++;
793                 }
794                 tmp = min(tmp, next_offset - file_key.offset);
795                 tmp >>= root->fs_info->sb->s_blocksize_bits;
796                 tmp = max((u64)1, tmp);
797                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
798                 ins_size = csum_size * tmp;
799         } else {
800                 ins_size = csum_size;
801         }
802         path->leave_spinning = 1;
803         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
804                                       ins_size);
805         path->leave_spinning = 0;
806         if (ret < 0)
807                 goto fail_unlock;
808         if (ret != 0) {
809                 WARN_ON(1);
810                 goto fail_unlock;
811         }
812 csum:
813         leaf = path->nodes[0];
814         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
815         ret = 0;
816         item = (struct btrfs_csum_item *)((unsigned char *)item +
817                                           csum_offset * csum_size);
818 found:
819         item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
820         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
821                                       btrfs_item_size_nr(leaf, path->slots[0]));
822 next_sector:
823
824         write_extent_buffer(leaf, &sector_sum->sum, (unsigned long)item, csum_size);
825
826         total_bytes += root->sectorsize;
827         sector_sum++;
828         if (total_bytes < sums->len) {
829                 item = (struct btrfs_csum_item *)((char *)item +
830                                                   csum_size);
831                 if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
832                     sector_sum->bytenr) {
833                         bytenr = sector_sum->bytenr;
834                         goto next_sector;
835                 }
836         }
837
838         btrfs_mark_buffer_dirty(path->nodes[0]);
839         if (total_bytes < sums->len) {
840                 btrfs_release_path(path);
841                 cond_resched();
842                 goto again;
843         }
844 out:
845         btrfs_free_path(path);
846         return ret;
847
848 fail_unlock:
849         goto out;
850 }