Merge branch 'alloc_path' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh...
[linux-2.6.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         if (!path)
295                 return -ENOMEM;
296
297         if (search_commit) {
298                 path->skip_locking = 1;
299                 path->reada = 2;
300                 path->search_commit_root = 1;
301         }
302
303         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
304         key.offset = start;
305         key.type = BTRFS_EXTENT_CSUM_KEY;
306
307         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
308         if (ret < 0)
309                 goto fail;
310         if (ret > 0 && path->slots[0] > 0) {
311                 leaf = path->nodes[0];
312                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
313                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
314                     key.type == BTRFS_EXTENT_CSUM_KEY) {
315                         offset = (start - key.offset) >>
316                                  root->fs_info->sb->s_blocksize_bits;
317                         if (offset * csum_size <
318                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
319                                 path->slots[0]--;
320                 }
321         }
322
323         while (start <= end) {
324                 leaf = path->nodes[0];
325                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
326                         ret = btrfs_next_leaf(root, path);
327                         if (ret < 0)
328                                 goto fail;
329                         if (ret > 0)
330                                 break;
331                         leaf = path->nodes[0];
332                 }
333
334                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
335                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
336                     key.type != BTRFS_EXTENT_CSUM_KEY)
337                         break;
338
339                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
340                 if (key.offset > end)
341                         break;
342
343                 if (key.offset > start)
344                         start = key.offset;
345
346                 size = btrfs_item_size_nr(leaf, path->slots[0]);
347                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
348                 if (csum_end <= start) {
349                         path->slots[0]++;
350                         continue;
351                 }
352
353                 csum_end = min(csum_end, end + 1);
354                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
355                                       struct btrfs_csum_item);
356                 while (start < csum_end) {
357                         size = min_t(size_t, csum_end - start,
358                                         MAX_ORDERED_SUM_BYTES(root));
359                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
360                                         GFP_NOFS);
361                         BUG_ON(!sums);
362
363                         sector_sum = sums->sums;
364                         sums->bytenr = start;
365                         sums->len = size;
366
367                         offset = (start - key.offset) >>
368                                 root->fs_info->sb->s_blocksize_bits;
369                         offset *= csum_size;
370
371                         while (size > 0) {
372                                 read_extent_buffer(path->nodes[0],
373                                                 &sector_sum->sum,
374                                                 ((unsigned long)item) +
375                                                 offset, csum_size);
376                                 sector_sum->bytenr = start;
377
378                                 size -= root->sectorsize;
379                                 start += root->sectorsize;
380                                 offset += csum_size;
381                                 sector_sum++;
382                         }
383                         list_add_tail(&sums->list, list);
384                 }
385                 path->slots[0]++;
386         }
387         ret = 0;
388 fail:
389         btrfs_free_path(path);
390         return ret;
391 }
392
393 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
394                        struct bio *bio, u64 file_start, int contig)
395 {
396         struct btrfs_ordered_sum *sums;
397         struct btrfs_sector_sum *sector_sum;
398         struct btrfs_ordered_extent *ordered;
399         char *data;
400         struct bio_vec *bvec = bio->bi_io_vec;
401         int bio_index = 0;
402         unsigned long total_bytes = 0;
403         unsigned long this_sum_bytes = 0;
404         u64 offset;
405         u64 disk_bytenr;
406
407         WARN_ON(bio->bi_vcnt <= 0);
408         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
409         if (!sums)
410                 return -ENOMEM;
411
412         sector_sum = sums->sums;
413         disk_bytenr = (u64)bio->bi_sector << 9;
414         sums->len = bio->bi_size;
415         INIT_LIST_HEAD(&sums->list);
416
417         if (contig)
418                 offset = file_start;
419         else
420                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
421
422         ordered = btrfs_lookup_ordered_extent(inode, offset);
423         BUG_ON(!ordered);
424         sums->bytenr = ordered->start;
425
426         while (bio_index < bio->bi_vcnt) {
427                 if (!contig)
428                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
429
430                 if (!contig && (offset >= ordered->file_offset + ordered->len ||
431                     offset < ordered->file_offset)) {
432                         unsigned long bytes_left;
433                         sums->len = this_sum_bytes;
434                         this_sum_bytes = 0;
435                         btrfs_add_ordered_sum(inode, ordered, sums);
436                         btrfs_put_ordered_extent(ordered);
437
438                         bytes_left = bio->bi_size - total_bytes;
439
440                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
441                                        GFP_NOFS);
442                         BUG_ON(!sums);
443                         sector_sum = sums->sums;
444                         sums->len = bytes_left;
445                         ordered = btrfs_lookup_ordered_extent(inode, offset);
446                         BUG_ON(!ordered);
447                         sums->bytenr = ordered->start;
448                 }
449
450                 data = kmap_atomic(bvec->bv_page, KM_USER0);
451                 sector_sum->sum = ~(u32)0;
452                 sector_sum->sum = btrfs_csum_data(root,
453                                                   data + bvec->bv_offset,
454                                                   sector_sum->sum,
455                                                   bvec->bv_len);
456                 kunmap_atomic(data, KM_USER0);
457                 btrfs_csum_final(sector_sum->sum,
458                                  (char *)&sector_sum->sum);
459                 sector_sum->bytenr = disk_bytenr;
460
461                 sector_sum++;
462                 bio_index++;
463                 total_bytes += bvec->bv_len;
464                 this_sum_bytes += bvec->bv_len;
465                 disk_bytenr += bvec->bv_len;
466                 offset += bvec->bv_len;
467                 bvec++;
468         }
469         this_sum_bytes = 0;
470         btrfs_add_ordered_sum(inode, ordered, sums);
471         btrfs_put_ordered_extent(ordered);
472         return 0;
473 }
474
475 /*
476  * helper function for csum removal, this expects the
477  * key to describe the csum pointed to by the path, and it expects
478  * the csum to overlap the range [bytenr, len]
479  *
480  * The csum should not be entirely contained in the range and the
481  * range should not be entirely contained in the csum.
482  *
483  * This calls btrfs_truncate_item with the correct args based on the
484  * overlap, and fixes up the key as required.
485  */
486 static noinline int truncate_one_csum(struct btrfs_trans_handle *trans,
487                                       struct btrfs_root *root,
488                                       struct btrfs_path *path,
489                                       struct btrfs_key *key,
490                                       u64 bytenr, u64 len)
491 {
492         struct extent_buffer *leaf;
493         u16 csum_size =
494                 btrfs_super_csum_size(&root->fs_info->super_copy);
495         u64 csum_end;
496         u64 end_byte = bytenr + len;
497         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
498         int ret;
499
500         leaf = path->nodes[0];
501         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
502         csum_end <<= root->fs_info->sb->s_blocksize_bits;
503         csum_end += key->offset;
504
505         if (key->offset < bytenr && csum_end <= end_byte) {
506                 /*
507                  *         [ bytenr - len ]
508                  *         [   ]
509                  *   [csum     ]
510                  *   A simple truncate off the end of the item
511                  */
512                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
513                 new_size *= csum_size;
514                 ret = btrfs_truncate_item(trans, root, path, new_size, 1);
515         } else if (key->offset >= bytenr && csum_end > end_byte &&
516                    end_byte > key->offset) {
517                 /*
518                  *         [ bytenr - len ]
519                  *                 [ ]
520                  *                 [csum     ]
521                  * we need to truncate from the beginning of the csum
522                  */
523                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
524                 new_size *= csum_size;
525
526                 ret = btrfs_truncate_item(trans, root, path, new_size, 0);
527
528                 key->offset = end_byte;
529                 ret = btrfs_set_item_key_safe(trans, root, path, key);
530                 BUG_ON(ret);
531         } else {
532                 BUG();
533         }
534         return 0;
535 }
536
537 /*
538  * deletes the csum items from the csum tree for a given
539  * range of bytes.
540  */
541 int btrfs_del_csums(struct btrfs_trans_handle *trans,
542                     struct btrfs_root *root, u64 bytenr, u64 len)
543 {
544         struct btrfs_path *path;
545         struct btrfs_key key;
546         u64 end_byte = bytenr + len;
547         u64 csum_end;
548         struct extent_buffer *leaf;
549         int ret;
550         u16 csum_size =
551                 btrfs_super_csum_size(&root->fs_info->super_copy);
552         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
553
554         root = root->fs_info->csum_root;
555
556         path = btrfs_alloc_path();
557         if (!path)
558                 return -ENOMEM;
559
560         while (1) {
561                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
562                 key.offset = end_byte - 1;
563                 key.type = BTRFS_EXTENT_CSUM_KEY;
564
565                 path->leave_spinning = 1;
566                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
567                 if (ret > 0) {
568                         if (path->slots[0] == 0)
569                                 break;
570                         path->slots[0]--;
571                 } else if (ret < 0) {
572                         break;
573                 }
574
575                 leaf = path->nodes[0];
576                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
577
578                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
579                     key.type != BTRFS_EXTENT_CSUM_KEY) {
580                         break;
581                 }
582
583                 if (key.offset >= end_byte)
584                         break;
585
586                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
587                 csum_end <<= blocksize_bits;
588                 csum_end += key.offset;
589
590                 /* this csum ends before we start, we're done */
591                 if (csum_end <= bytenr)
592                         break;
593
594                 /* delete the entire item, it is inside our range */
595                 if (key.offset >= bytenr && csum_end <= end_byte) {
596                         ret = btrfs_del_item(trans, root, path);
597                         if (ret)
598                                 goto out;
599                         if (key.offset == bytenr)
600                                 break;
601                 } else if (key.offset < bytenr && csum_end > end_byte) {
602                         unsigned long offset;
603                         unsigned long shift_len;
604                         unsigned long item_offset;
605                         /*
606                          *        [ bytenr - len ]
607                          *     [csum                ]
608                          *
609                          * Our bytes are in the middle of the csum,
610                          * we need to split this item and insert a new one.
611                          *
612                          * But we can't drop the path because the
613                          * csum could change, get removed, extended etc.
614                          *
615                          * The trick here is the max size of a csum item leaves
616                          * enough room in the tree block for a single
617                          * item header.  So, we split the item in place,
618                          * adding a new header pointing to the existing
619                          * bytes.  Then we loop around again and we have
620                          * a nicely formed csum item that we can neatly
621                          * truncate.
622                          */
623                         offset = (bytenr - key.offset) >> blocksize_bits;
624                         offset *= csum_size;
625
626                         shift_len = (len >> blocksize_bits) * csum_size;
627
628                         item_offset = btrfs_item_ptr_offset(leaf,
629                                                             path->slots[0]);
630
631                         memset_extent_buffer(leaf, 0, item_offset + offset,
632                                              shift_len);
633                         key.offset = bytenr;
634
635                         /*
636                          * btrfs_split_item returns -EAGAIN when the
637                          * item changed size or key
638                          */
639                         ret = btrfs_split_item(trans, root, path, &key, offset);
640                         BUG_ON(ret && ret != -EAGAIN);
641
642                         key.offset = end_byte - 1;
643                 } else {
644                         ret = truncate_one_csum(trans, root, path,
645                                                 &key, bytenr, len);
646                         BUG_ON(ret);
647                         if (key.offset < bytenr)
648                                 break;
649                 }
650                 btrfs_release_path(path);
651         }
652         ret = 0;
653 out:
654         btrfs_free_path(path);
655         return ret;
656 }
657
658 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
659                            struct btrfs_root *root,
660                            struct btrfs_ordered_sum *sums)
661 {
662         u64 bytenr;
663         int ret;
664         struct btrfs_key file_key;
665         struct btrfs_key found_key;
666         u64 next_offset;
667         u64 total_bytes = 0;
668         int found_next;
669         struct btrfs_path *path;
670         struct btrfs_csum_item *item;
671         struct btrfs_csum_item *item_end;
672         struct extent_buffer *leaf = NULL;
673         u64 csum_offset;
674         struct btrfs_sector_sum *sector_sum;
675         u32 nritems;
676         u32 ins_size;
677         u16 csum_size =
678                 btrfs_super_csum_size(&root->fs_info->super_copy);
679
680         path = btrfs_alloc_path();
681         if (!path)
682                 return -ENOMEM;
683
684         sector_sum = sums->sums;
685 again:
686         next_offset = (u64)-1;
687         found_next = 0;
688         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
689         file_key.offset = sector_sum->bytenr;
690         bytenr = sector_sum->bytenr;
691         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
692
693         item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
694         if (!IS_ERR(item)) {
695                 leaf = path->nodes[0];
696                 ret = 0;
697                 goto found;
698         }
699         ret = PTR_ERR(item);
700         if (ret != -EFBIG && ret != -ENOENT)
701                 goto fail_unlock;
702
703         if (ret == -EFBIG) {
704                 u32 item_size;
705                 /* we found one, but it isn't big enough yet */
706                 leaf = path->nodes[0];
707                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
708                 if ((item_size / csum_size) >=
709                     MAX_CSUM_ITEMS(root, csum_size)) {
710                         /* already at max size, make a new one */
711                         goto insert;
712                 }
713         } else {
714                 int slot = path->slots[0] + 1;
715                 /* we didn't find a csum item, insert one */
716                 nritems = btrfs_header_nritems(path->nodes[0]);
717                 if (path->slots[0] >= nritems - 1) {
718                         ret = btrfs_next_leaf(root, path);
719                         if (ret == 1)
720                                 found_next = 1;
721                         if (ret != 0)
722                                 goto insert;
723                         slot = 0;
724                 }
725                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
726                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
727                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
728                         found_next = 1;
729                         goto insert;
730                 }
731                 next_offset = found_key.offset;
732                 found_next = 1;
733                 goto insert;
734         }
735
736         /*
737          * at this point, we know the tree has an item, but it isn't big
738          * enough yet to put our csum in.  Grow it
739          */
740         btrfs_release_path(path);
741         ret = btrfs_search_slot(trans, root, &file_key, path,
742                                 csum_size, 1);
743         if (ret < 0)
744                 goto fail_unlock;
745
746         if (ret > 0) {
747                 if (path->slots[0] == 0)
748                         goto insert;
749                 path->slots[0]--;
750         }
751
752         leaf = path->nodes[0];
753         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
754         csum_offset = (bytenr - found_key.offset) >>
755                         root->fs_info->sb->s_blocksize_bits;
756
757         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
758             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
759             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
760                 goto insert;
761         }
762
763         if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
764             csum_size) {
765                 u32 diff = (csum_offset + 1) * csum_size;
766
767                 /*
768                  * is the item big enough already?  we dropped our lock
769                  * before and need to recheck
770                  */
771                 if (diff < btrfs_item_size_nr(leaf, path->slots[0]))
772                         goto csum;
773
774                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
775                 if (diff != csum_size)
776                         goto insert;
777
778                 ret = btrfs_extend_item(trans, root, path, diff);
779                 goto csum;
780         }
781
782 insert:
783         btrfs_release_path(path);
784         csum_offset = 0;
785         if (found_next) {
786                 u64 tmp = total_bytes + root->sectorsize;
787                 u64 next_sector = sector_sum->bytenr;
788                 struct btrfs_sector_sum *next = sector_sum + 1;
789
790                 while (tmp < sums->len) {
791                         if (next_sector + root->sectorsize != next->bytenr)
792                                 break;
793                         tmp += root->sectorsize;
794                         next_sector = next->bytenr;
795                         next++;
796                 }
797                 tmp = min(tmp, next_offset - file_key.offset);
798                 tmp >>= root->fs_info->sb->s_blocksize_bits;
799                 tmp = max((u64)1, tmp);
800                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
801                 ins_size = csum_size * tmp;
802         } else {
803                 ins_size = csum_size;
804         }
805         path->leave_spinning = 1;
806         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
807                                       ins_size);
808         path->leave_spinning = 0;
809         if (ret < 0)
810                 goto fail_unlock;
811         if (ret != 0) {
812                 WARN_ON(1);
813                 goto fail_unlock;
814         }
815 csum:
816         leaf = path->nodes[0];
817         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
818         ret = 0;
819         item = (struct btrfs_csum_item *)((unsigned char *)item +
820                                           csum_offset * csum_size);
821 found:
822         item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
823         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
824                                       btrfs_item_size_nr(leaf, path->slots[0]));
825 next_sector:
826
827         write_extent_buffer(leaf, &sector_sum->sum, (unsigned long)item, csum_size);
828
829         total_bytes += root->sectorsize;
830         sector_sum++;
831         if (total_bytes < sums->len) {
832                 item = (struct btrfs_csum_item *)((char *)item +
833                                                   csum_size);
834                 if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
835                     sector_sum->bytenr) {
836                         bytenr = sector_sum->bytenr;
837                         goto next_sector;
838                 }
839         }
840
841         btrfs_mark_buffer_dirty(path->nodes[0]);
842         if (total_bytes < sums->len) {
843                 btrfs_release_path(path);
844                 cond_resched();
845                 goto again;
846         }
847 out:
848         btrfs_free_path(path);
849         return ret;
850
851 fail_unlock:
852         goto out;
853 }