Btrfs: check free space in block group before searching for a cluster
[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         BUG_ON(!path);
52         file_key.objectid = objectid;
53         file_key.offset = pos;
54         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
55
56         path->leave_spinning = 1;
57         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
58                                       sizeof(*item));
59         if (ret < 0)
60                 goto out;
61         BUG_ON(ret);
62         leaf = path->nodes[0];
63         item = btrfs_item_ptr(leaf, path->slots[0],
64                               struct btrfs_file_extent_item);
65         btrfs_set_file_extent_disk_bytenr(leaf, item, disk_offset);
66         btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
67         btrfs_set_file_extent_offset(leaf, item, offset);
68         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
69         btrfs_set_file_extent_ram_bytes(leaf, item, ram_bytes);
70         btrfs_set_file_extent_generation(leaf, item, trans->transid);
71         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
72         btrfs_set_file_extent_compression(leaf, item, compression);
73         btrfs_set_file_extent_encryption(leaf, item, encryption);
74         btrfs_set_file_extent_other_encoding(leaf, item, other_encoding);
75
76         btrfs_mark_buffer_dirty(leaf);
77 out:
78         btrfs_free_path(path);
79         return ret;
80 }
81
82 struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
83                                           struct btrfs_root *root,
84                                           struct btrfs_path *path,
85                                           u64 bytenr, int cow)
86 {
87         int ret;
88         struct btrfs_key file_key;
89         struct btrfs_key found_key;
90         struct btrfs_csum_item *item;
91         struct extent_buffer *leaf;
92         u64 csum_offset = 0;
93         u16 csum_size =
94                 btrfs_super_csum_size(&root->fs_info->super_copy);
95         int csums_in_item;
96
97         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
98         file_key.offset = bytenr;
99         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
100         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
101         if (ret < 0)
102                 goto fail;
103         leaf = path->nodes[0];
104         if (ret > 0) {
105                 ret = 1;
106                 if (path->slots[0] == 0)
107                         goto fail;
108                 path->slots[0]--;
109                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
110                 if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY)
111                         goto fail;
112
113                 csum_offset = (bytenr - found_key.offset) >>
114                                 root->fs_info->sb->s_blocksize_bits;
115                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
116                 csums_in_item /= csum_size;
117
118                 if (csum_offset >= csums_in_item) {
119                         ret = -EFBIG;
120                         goto fail;
121                 }
122         }
123         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
124         item = (struct btrfs_csum_item *)((unsigned char *)item +
125                                           csum_offset * csum_size);
126         return item;
127 fail:
128         if (ret > 0)
129                 ret = -ENOENT;
130         return ERR_PTR(ret);
131 }
132
133
134 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
135                              struct btrfs_root *root,
136                              struct btrfs_path *path, u64 objectid,
137                              u64 offset, int mod)
138 {
139         int ret;
140         struct btrfs_key file_key;
141         int ins_len = mod < 0 ? -1 : 0;
142         int cow = mod != 0;
143
144         file_key.objectid = objectid;
145         file_key.offset = offset;
146         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
147         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
148         return ret;
149 }
150
151
152 static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
153                                    struct inode *inode, struct bio *bio,
154                                    u64 logical_offset, u32 *dst, int dio)
155 {
156         u32 sum;
157         struct bio_vec *bvec = bio->bi_io_vec;
158         int bio_index = 0;
159         u64 offset = 0;
160         u64 item_start_offset = 0;
161         u64 item_last_offset = 0;
162         u64 disk_bytenr;
163         u32 diff;
164         u16 csum_size =
165                 btrfs_super_csum_size(&root->fs_info->super_copy);
166         int ret;
167         struct btrfs_path *path;
168         struct btrfs_csum_item *item = NULL;
169         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
170
171         path = btrfs_alloc_path();
172         if (bio->bi_size > PAGE_CACHE_SIZE * 8)
173                 path->reada = 2;
174
175         WARN_ON(bio->bi_vcnt <= 0);
176
177         disk_bytenr = (u64)bio->bi_sector << 9;
178         if (dio)
179                 offset = logical_offset;
180         while (bio_index < bio->bi_vcnt) {
181                 if (!dio)
182                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
183                 ret = btrfs_find_ordered_sum(inode, offset, disk_bytenr, &sum);
184                 if (ret == 0)
185                         goto found;
186
187                 if (!item || disk_bytenr < item_start_offset ||
188                     disk_bytenr >= item_last_offset) {
189                         struct btrfs_key found_key;
190                         u32 item_size;
191
192                         if (item)
193                                 btrfs_release_path(root, path);
194                         item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
195                                                  path, disk_bytenr, 0);
196                         if (IS_ERR(item)) {
197                                 ret = PTR_ERR(item);
198                                 if (ret == -ENOENT || ret == -EFBIG)
199                                         ret = 0;
200                                 sum = 0;
201                                 if (BTRFS_I(inode)->root->root_key.objectid ==
202                                     BTRFS_DATA_RELOC_TREE_OBJECTID) {
203                                         set_extent_bits(io_tree, offset,
204                                                 offset + bvec->bv_len - 1,
205                                                 EXTENT_NODATASUM, GFP_NOFS);
206                                 } else {
207                                         printk(KERN_INFO "btrfs no csum found "
208                                                "for inode %lu start %llu\n",
209                                                inode->i_ino,
210                                                (unsigned long long)offset);
211                                 }
212                                 item = NULL;
213                                 btrfs_release_path(root, path);
214                                 goto found;
215                         }
216                         btrfs_item_key_to_cpu(path->nodes[0], &found_key,
217                                               path->slots[0]);
218
219                         item_start_offset = found_key.offset;
220                         item_size = btrfs_item_size_nr(path->nodes[0],
221                                                        path->slots[0]);
222                         item_last_offset = item_start_offset +
223                                 (item_size / csum_size) *
224                                 root->sectorsize;
225                         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
226                                               struct btrfs_csum_item);
227                 }
228                 /*
229                  * this byte range must be able to fit inside
230                  * a single leaf so it will also fit inside a u32
231                  */
232                 diff = disk_bytenr - item_start_offset;
233                 diff = diff / root->sectorsize;
234                 diff = diff * csum_size;
235
236                 read_extent_buffer(path->nodes[0], &sum,
237                                    ((unsigned long)item) + diff,
238                                    csum_size);
239 found:
240                 if (dst)
241                         *dst++ = sum;
242                 else
243                         set_state_private(io_tree, offset, sum);
244                 disk_bytenr += bvec->bv_len;
245                 offset += bvec->bv_len;
246                 bio_index++;
247                 bvec++;
248         }
249         btrfs_free_path(path);
250         return 0;
251 }
252
253 int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
254                           struct bio *bio, u32 *dst)
255 {
256         return __btrfs_lookup_bio_sums(root, inode, bio, 0, dst, 0);
257 }
258
259 int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
260                               struct bio *bio, u64 offset, u32 *dst)
261 {
262         return __btrfs_lookup_bio_sums(root, inode, bio, offset, dst, 1);
263 }
264
265 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
266                              struct list_head *list)
267 {
268         struct btrfs_key key;
269         struct btrfs_path *path;
270         struct extent_buffer *leaf;
271         struct btrfs_ordered_sum *sums;
272         struct btrfs_sector_sum *sector_sum;
273         struct btrfs_csum_item *item;
274         unsigned long offset;
275         int ret;
276         size_t size;
277         u64 csum_end;
278         u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
279
280         path = btrfs_alloc_path();
281         BUG_ON(!path);
282
283         key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
284         key.offset = start;
285         key.type = BTRFS_EXTENT_CSUM_KEY;
286
287         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
288         if (ret < 0)
289                 goto fail;
290         if (ret > 0 && path->slots[0] > 0) {
291                 leaf = path->nodes[0];
292                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
293                 if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
294                     key.type == BTRFS_EXTENT_CSUM_KEY) {
295                         offset = (start - key.offset) >>
296                                  root->fs_info->sb->s_blocksize_bits;
297                         if (offset * csum_size <
298                             btrfs_item_size_nr(leaf, path->slots[0] - 1))
299                                 path->slots[0]--;
300                 }
301         }
302
303         while (start <= end) {
304                 leaf = path->nodes[0];
305                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
306                         ret = btrfs_next_leaf(root, path);
307                         if (ret < 0)
308                                 goto fail;
309                         if (ret > 0)
310                                 break;
311                         leaf = path->nodes[0];
312                 }
313
314                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
315                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
316                     key.type != BTRFS_EXTENT_CSUM_KEY)
317                         break;
318
319                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
320                 if (key.offset > end)
321                         break;
322
323                 if (key.offset > start)
324                         start = key.offset;
325
326                 size = btrfs_item_size_nr(leaf, path->slots[0]);
327                 csum_end = key.offset + (size / csum_size) * root->sectorsize;
328                 if (csum_end <= start) {
329                         path->slots[0]++;
330                         continue;
331                 }
332
333                 csum_end = min(csum_end, end + 1);
334                 item = btrfs_item_ptr(path->nodes[0], path->slots[0],
335                                       struct btrfs_csum_item);
336                 while (start < csum_end) {
337                         size = min_t(size_t, csum_end - start,
338                                         MAX_ORDERED_SUM_BYTES(root));
339                         sums = kzalloc(btrfs_ordered_sum_size(root, size),
340                                         GFP_NOFS);
341                         BUG_ON(!sums);
342
343                         sector_sum = sums->sums;
344                         sums->bytenr = start;
345                         sums->len = size;
346
347                         offset = (start - key.offset) >>
348                                 root->fs_info->sb->s_blocksize_bits;
349                         offset *= csum_size;
350
351                         while (size > 0) {
352                                 read_extent_buffer(path->nodes[0],
353                                                 &sector_sum->sum,
354                                                 ((unsigned long)item) +
355                                                 offset, csum_size);
356                                 sector_sum->bytenr = start;
357
358                                 size -= root->sectorsize;
359                                 start += root->sectorsize;
360                                 offset += csum_size;
361                                 sector_sum++;
362                         }
363                         list_add_tail(&sums->list, list);
364                 }
365                 path->slots[0]++;
366         }
367         ret = 0;
368 fail:
369         btrfs_free_path(path);
370         return ret;
371 }
372
373 int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
374                        struct bio *bio, u64 file_start, int contig)
375 {
376         struct btrfs_ordered_sum *sums;
377         struct btrfs_sector_sum *sector_sum;
378         struct btrfs_ordered_extent *ordered;
379         char *data;
380         struct bio_vec *bvec = bio->bi_io_vec;
381         int bio_index = 0;
382         unsigned long total_bytes = 0;
383         unsigned long this_sum_bytes = 0;
384         u64 offset;
385         u64 disk_bytenr;
386
387         WARN_ON(bio->bi_vcnt <= 0);
388         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
389         if (!sums)
390                 return -ENOMEM;
391
392         sector_sum = sums->sums;
393         disk_bytenr = (u64)bio->bi_sector << 9;
394         sums->len = bio->bi_size;
395         INIT_LIST_HEAD(&sums->list);
396
397         if (contig)
398                 offset = file_start;
399         else
400                 offset = page_offset(bvec->bv_page) + bvec->bv_offset;
401
402         ordered = btrfs_lookup_ordered_extent(inode, offset);
403         BUG_ON(!ordered);
404         sums->bytenr = ordered->start;
405
406         while (bio_index < bio->bi_vcnt) {
407                 if (!contig)
408                         offset = page_offset(bvec->bv_page) + bvec->bv_offset;
409
410                 if (!contig && (offset >= ordered->file_offset + ordered->len ||
411                     offset < ordered->file_offset)) {
412                         unsigned long bytes_left;
413                         sums->len = this_sum_bytes;
414                         this_sum_bytes = 0;
415                         btrfs_add_ordered_sum(inode, ordered, sums);
416                         btrfs_put_ordered_extent(ordered);
417
418                         bytes_left = bio->bi_size - total_bytes;
419
420                         sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
421                                        GFP_NOFS);
422                         BUG_ON(!sums);
423                         sector_sum = sums->sums;
424                         sums->len = bytes_left;
425                         ordered = btrfs_lookup_ordered_extent(inode, offset);
426                         BUG_ON(!ordered);
427                         sums->bytenr = ordered->start;
428                 }
429
430                 data = kmap_atomic(bvec->bv_page, KM_USER0);
431                 sector_sum->sum = ~(u32)0;
432                 sector_sum->sum = btrfs_csum_data(root,
433                                                   data + bvec->bv_offset,
434                                                   sector_sum->sum,
435                                                   bvec->bv_len);
436                 kunmap_atomic(data, KM_USER0);
437                 btrfs_csum_final(sector_sum->sum,
438                                  (char *)&sector_sum->sum);
439                 sector_sum->bytenr = disk_bytenr;
440
441                 sector_sum++;
442                 bio_index++;
443                 total_bytes += bvec->bv_len;
444                 this_sum_bytes += bvec->bv_len;
445                 disk_bytenr += bvec->bv_len;
446                 offset += bvec->bv_len;
447                 bvec++;
448         }
449         this_sum_bytes = 0;
450         btrfs_add_ordered_sum(inode, ordered, sums);
451         btrfs_put_ordered_extent(ordered);
452         return 0;
453 }
454
455 /*
456  * helper function for csum removal, this expects the
457  * key to describe the csum pointed to by the path, and it expects
458  * the csum to overlap the range [bytenr, len]
459  *
460  * The csum should not be entirely contained in the range and the
461  * range should not be entirely contained in the csum.
462  *
463  * This calls btrfs_truncate_item with the correct args based on the
464  * overlap, and fixes up the key as required.
465  */
466 static noinline int truncate_one_csum(struct btrfs_trans_handle *trans,
467                                       struct btrfs_root *root,
468                                       struct btrfs_path *path,
469                                       struct btrfs_key *key,
470                                       u64 bytenr, u64 len)
471 {
472         struct extent_buffer *leaf;
473         u16 csum_size =
474                 btrfs_super_csum_size(&root->fs_info->super_copy);
475         u64 csum_end;
476         u64 end_byte = bytenr + len;
477         u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
478         int ret;
479
480         leaf = path->nodes[0];
481         csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
482         csum_end <<= root->fs_info->sb->s_blocksize_bits;
483         csum_end += key->offset;
484
485         if (key->offset < bytenr && csum_end <= end_byte) {
486                 /*
487                  *         [ bytenr - len ]
488                  *         [   ]
489                  *   [csum     ]
490                  *   A simple truncate off the end of the item
491                  */
492                 u32 new_size = (bytenr - key->offset) >> blocksize_bits;
493                 new_size *= csum_size;
494                 ret = btrfs_truncate_item(trans, root, path, new_size, 1);
495                 BUG_ON(ret);
496         } else if (key->offset >= bytenr && csum_end > end_byte &&
497                    end_byte > key->offset) {
498                 /*
499                  *         [ bytenr - len ]
500                  *                 [ ]
501                  *                 [csum     ]
502                  * we need to truncate from the beginning of the csum
503                  */
504                 u32 new_size = (csum_end - end_byte) >> blocksize_bits;
505                 new_size *= csum_size;
506
507                 ret = btrfs_truncate_item(trans, root, path, new_size, 0);
508                 BUG_ON(ret);
509
510                 key->offset = end_byte;
511                 ret = btrfs_set_item_key_safe(trans, root, path, key);
512                 BUG_ON(ret);
513         } else {
514                 BUG();
515         }
516         return 0;
517 }
518
519 /*
520  * deletes the csum items from the csum tree for a given
521  * range of bytes.
522  */
523 int btrfs_del_csums(struct btrfs_trans_handle *trans,
524                     struct btrfs_root *root, u64 bytenr, u64 len)
525 {
526         struct btrfs_path *path;
527         struct btrfs_key key;
528         u64 end_byte = bytenr + len;
529         u64 csum_end;
530         struct extent_buffer *leaf;
531         int ret;
532         u16 csum_size =
533                 btrfs_super_csum_size(&root->fs_info->super_copy);
534         int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
535
536         root = root->fs_info->csum_root;
537
538         path = btrfs_alloc_path();
539         if (!path)
540                 return -ENOMEM;
541
542         while (1) {
543                 key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
544                 key.offset = end_byte - 1;
545                 key.type = BTRFS_EXTENT_CSUM_KEY;
546
547                 path->leave_spinning = 1;
548                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
549                 if (ret > 0) {
550                         if (path->slots[0] == 0)
551                                 goto out;
552                         path->slots[0]--;
553                 } else if (ret < 0) {
554                         goto out;
555                 }
556
557                 leaf = path->nodes[0];
558                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
559
560                 if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
561                     key.type != BTRFS_EXTENT_CSUM_KEY) {
562                         break;
563                 }
564
565                 if (key.offset >= end_byte)
566                         break;
567
568                 csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
569                 csum_end <<= blocksize_bits;
570                 csum_end += key.offset;
571
572                 /* this csum ends before we start, we're done */
573                 if (csum_end <= bytenr)
574                         break;
575
576                 /* delete the entire item, it is inside our range */
577                 if (key.offset >= bytenr && csum_end <= end_byte) {
578                         ret = btrfs_del_item(trans, root, path);
579                         BUG_ON(ret);
580                         if (key.offset == bytenr)
581                                 break;
582                 } else if (key.offset < bytenr && csum_end > end_byte) {
583                         unsigned long offset;
584                         unsigned long shift_len;
585                         unsigned long item_offset;
586                         /*
587                          *        [ bytenr - len ]
588                          *     [csum                ]
589                          *
590                          * Our bytes are in the middle of the csum,
591                          * we need to split this item and insert a new one.
592                          *
593                          * But we can't drop the path because the
594                          * csum could change, get removed, extended etc.
595                          *
596                          * The trick here is the max size of a csum item leaves
597                          * enough room in the tree block for a single
598                          * item header.  So, we split the item in place,
599                          * adding a new header pointing to the existing
600                          * bytes.  Then we loop around again and we have
601                          * a nicely formed csum item that we can neatly
602                          * truncate.
603                          */
604                         offset = (bytenr - key.offset) >> blocksize_bits;
605                         offset *= csum_size;
606
607                         shift_len = (len >> blocksize_bits) * csum_size;
608
609                         item_offset = btrfs_item_ptr_offset(leaf,
610                                                             path->slots[0]);
611
612                         memset_extent_buffer(leaf, 0, item_offset + offset,
613                                              shift_len);
614                         key.offset = bytenr;
615
616                         /*
617                          * btrfs_split_item returns -EAGAIN when the
618                          * item changed size or key
619                          */
620                         ret = btrfs_split_item(trans, root, path, &key, offset);
621                         BUG_ON(ret && ret != -EAGAIN);
622
623                         key.offset = end_byte - 1;
624                 } else {
625                         ret = truncate_one_csum(trans, root, path,
626                                                 &key, bytenr, len);
627                         BUG_ON(ret);
628                         if (key.offset < bytenr)
629                                 break;
630                 }
631                 btrfs_release_path(root, path);
632         }
633 out:
634         btrfs_free_path(path);
635         return 0;
636 }
637
638 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
639                            struct btrfs_root *root,
640                            struct btrfs_ordered_sum *sums)
641 {
642         u64 bytenr;
643         int ret;
644         struct btrfs_key file_key;
645         struct btrfs_key found_key;
646         u64 next_offset;
647         u64 total_bytes = 0;
648         int found_next;
649         struct btrfs_path *path;
650         struct btrfs_csum_item *item;
651         struct btrfs_csum_item *item_end;
652         struct extent_buffer *leaf = NULL;
653         u64 csum_offset;
654         struct btrfs_sector_sum *sector_sum;
655         u32 nritems;
656         u32 ins_size;
657         char *eb_map;
658         char *eb_token;
659         unsigned long map_len;
660         unsigned long map_start;
661         u16 csum_size =
662                 btrfs_super_csum_size(&root->fs_info->super_copy);
663
664         path = btrfs_alloc_path();
665         BUG_ON(!path);
666         sector_sum = sums->sums;
667 again:
668         next_offset = (u64)-1;
669         found_next = 0;
670         file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
671         file_key.offset = sector_sum->bytenr;
672         bytenr = sector_sum->bytenr;
673         btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
674
675         item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
676         if (!IS_ERR(item)) {
677                 leaf = path->nodes[0];
678                 ret = 0;
679                 goto found;
680         }
681         ret = PTR_ERR(item);
682         if (ret != -EFBIG && ret != -ENOENT)
683                 goto fail_unlock;
684
685         if (ret == -EFBIG) {
686                 u32 item_size;
687                 /* we found one, but it isn't big enough yet */
688                 leaf = path->nodes[0];
689                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
690                 if ((item_size / csum_size) >=
691                     MAX_CSUM_ITEMS(root, csum_size)) {
692                         /* already at max size, make a new one */
693                         goto insert;
694                 }
695         } else {
696                 int slot = path->slots[0] + 1;
697                 /* we didn't find a csum item, insert one */
698                 nritems = btrfs_header_nritems(path->nodes[0]);
699                 if (path->slots[0] >= nritems - 1) {
700                         ret = btrfs_next_leaf(root, path);
701                         if (ret == 1)
702                                 found_next = 1;
703                         if (ret != 0)
704                                 goto insert;
705                         slot = 0;
706                 }
707                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
708                 if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
709                     found_key.type != BTRFS_EXTENT_CSUM_KEY) {
710                         found_next = 1;
711                         goto insert;
712                 }
713                 next_offset = found_key.offset;
714                 found_next = 1;
715                 goto insert;
716         }
717
718         /*
719          * at this point, we know the tree has an item, but it isn't big
720          * enough yet to put our csum in.  Grow it
721          */
722         btrfs_release_path(root, path);
723         ret = btrfs_search_slot(trans, root, &file_key, path,
724                                 csum_size, 1);
725         if (ret < 0)
726                 goto fail_unlock;
727
728         if (ret > 0) {
729                 if (path->slots[0] == 0)
730                         goto insert;
731                 path->slots[0]--;
732         }
733
734         leaf = path->nodes[0];
735         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
736         csum_offset = (bytenr - found_key.offset) >>
737                         root->fs_info->sb->s_blocksize_bits;
738
739         if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
740             found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
741             csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
742                 goto insert;
743         }
744
745         if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
746             csum_size) {
747                 u32 diff = (csum_offset + 1) * csum_size;
748
749                 /*
750                  * is the item big enough already?  we dropped our lock
751                  * before and need to recheck
752                  */
753                 if (diff < btrfs_item_size_nr(leaf, path->slots[0]))
754                         goto csum;
755
756                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
757                 if (diff != csum_size)
758                         goto insert;
759
760                 ret = btrfs_extend_item(trans, root, path, diff);
761                 BUG_ON(ret);
762                 goto csum;
763         }
764
765 insert:
766         btrfs_release_path(root, path);
767         csum_offset = 0;
768         if (found_next) {
769                 u64 tmp = total_bytes + root->sectorsize;
770                 u64 next_sector = sector_sum->bytenr;
771                 struct btrfs_sector_sum *next = sector_sum + 1;
772
773                 while (tmp < sums->len) {
774                         if (next_sector + root->sectorsize != next->bytenr)
775                                 break;
776                         tmp += root->sectorsize;
777                         next_sector = next->bytenr;
778                         next++;
779                 }
780                 tmp = min(tmp, next_offset - file_key.offset);
781                 tmp >>= root->fs_info->sb->s_blocksize_bits;
782                 tmp = max((u64)1, tmp);
783                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
784                 ins_size = csum_size * tmp;
785         } else {
786                 ins_size = csum_size;
787         }
788         path->leave_spinning = 1;
789         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
790                                       ins_size);
791         path->leave_spinning = 0;
792         if (ret < 0)
793                 goto fail_unlock;
794         if (ret != 0) {
795                 WARN_ON(1);
796                 goto fail_unlock;
797         }
798 csum:
799         leaf = path->nodes[0];
800         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
801         ret = 0;
802         item = (struct btrfs_csum_item *)((unsigned char *)item +
803                                           csum_offset * csum_size);
804 found:
805         item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
806         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
807                                       btrfs_item_size_nr(leaf, path->slots[0]));
808         eb_token = NULL;
809 next_sector:
810
811         if (!eb_token ||
812            (unsigned long)item + csum_size >= map_start + map_len) {
813                 int err;
814
815                 if (eb_token)
816                         unmap_extent_buffer(leaf, eb_token, KM_USER1);
817                 eb_token = NULL;
818                 err = map_private_extent_buffer(leaf, (unsigned long)item,
819                                                 csum_size,
820                                                 &eb_token, &eb_map,
821                                                 &map_start, &map_len, KM_USER1);
822                 if (err)
823                         eb_token = NULL;
824         }
825         if (eb_token) {
826                 memcpy(eb_token + ((unsigned long)item & (PAGE_CACHE_SIZE - 1)),
827                        &sector_sum->sum, csum_size);
828         } else {
829                 write_extent_buffer(leaf, &sector_sum->sum,
830                                     (unsigned long)item, csum_size);
831         }
832
833         total_bytes += root->sectorsize;
834         sector_sum++;
835         if (total_bytes < sums->len) {
836                 item = (struct btrfs_csum_item *)((char *)item +
837                                                   csum_size);
838                 if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
839                     sector_sum->bytenr) {
840                         bytenr = sector_sum->bytenr;
841                         goto next_sector;
842                 }
843         }
844         if (eb_token) {
845                 unmap_extent_buffer(leaf, eb_token, KM_USER1);
846                 eb_token = NULL;
847         }
848         btrfs_mark_buffer_dirty(path->nodes[0]);
849         if (total_bytes < sums->len) {
850                 btrfs_release_path(root, path);
851                 cond_resched();
852                 goto again;
853         }
854 out:
855         btrfs_free_path(path);
856         return ret;
857
858 fail_unlock:
859         goto out;
860 }