Root/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
37int 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);
77out:
78    btrfs_free_path(path);
79    return ret;
80}
81
82struct 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;
127fail:
128    if (ret > 0)
129        ret = -ENOENT;
130    return ERR_PTR(ret);
131}
132
133
134int 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
152int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode,
153              struct bio *bio, u32 *dst)
154{
155    u32 sum;
156    struct bio_vec *bvec = bio->bi_io_vec;
157    int bio_index = 0;
158    u64 offset;
159    u64 item_start_offset = 0;
160    u64 item_last_offset = 0;
161    u64 disk_bytenr;
162    u32 diff;
163    u16 csum_size =
164        btrfs_super_csum_size(&root->fs_info->super_copy);
165    int ret;
166    struct btrfs_path *path;
167    struct btrfs_csum_item *item = NULL;
168    struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
169
170    path = btrfs_alloc_path();
171    if (bio->bi_size > PAGE_CACHE_SIZE * 8)
172        path->reada = 2;
173
174    WARN_ON(bio->bi_vcnt <= 0);
175
176    disk_bytenr = (u64)bio->bi_sector << 9;
177    while (bio_index < bio->bi_vcnt) {
178        offset = page_offset(bvec->bv_page) + bvec->bv_offset;
179        ret = btrfs_find_ordered_sum(inode, offset, disk_bytenr, &sum);
180        if (ret == 0)
181            goto found;
182
183        if (!item || disk_bytenr < item_start_offset ||
184            disk_bytenr >= item_last_offset) {
185            struct btrfs_key found_key;
186            u32 item_size;
187
188            if (item)
189                btrfs_release_path(root, path);
190            item = btrfs_lookup_csum(NULL, root->fs_info->csum_root,
191                         path, disk_bytenr, 0);
192            if (IS_ERR(item)) {
193                ret = PTR_ERR(item);
194                if (ret == -ENOENT || ret == -EFBIG)
195                    ret = 0;
196                sum = 0;
197                if (BTRFS_I(inode)->root->root_key.objectid ==
198                    BTRFS_DATA_RELOC_TREE_OBJECTID) {
199                    set_extent_bits(io_tree, offset,
200                        offset + bvec->bv_len - 1,
201                        EXTENT_NODATASUM, GFP_NOFS);
202                } else {
203                    printk(KERN_INFO "btrfs no csum found "
204                           "for inode %lu start %llu\n",
205                           inode->i_ino,
206                           (unsigned long long)offset);
207                }
208                item = NULL;
209                btrfs_release_path(root, path);
210                goto found;
211            }
212            btrfs_item_key_to_cpu(path->nodes[0], &found_key,
213                          path->slots[0]);
214
215            item_start_offset = found_key.offset;
216            item_size = btrfs_item_size_nr(path->nodes[0],
217                               path->slots[0]);
218            item_last_offset = item_start_offset +
219                (item_size / csum_size) *
220                root->sectorsize;
221            item = btrfs_item_ptr(path->nodes[0], path->slots[0],
222                          struct btrfs_csum_item);
223        }
224        /*
225         * this byte range must be able to fit inside
226         * a single leaf so it will also fit inside a u32
227         */
228        diff = disk_bytenr - item_start_offset;
229        diff = diff / root->sectorsize;
230        diff = diff * csum_size;
231
232        read_extent_buffer(path->nodes[0], &sum,
233                   ((unsigned long)item) + diff,
234                   csum_size);
235found:
236        if (dst)
237            *dst++ = sum;
238        else
239            set_state_private(io_tree, offset, sum);
240        disk_bytenr += bvec->bv_len;
241        bio_index++;
242        bvec++;
243    }
244    btrfs_free_path(path);
245    return 0;
246}
247
248int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
249                 struct list_head *list)
250{
251    struct btrfs_key key;
252    struct btrfs_path *path;
253    struct extent_buffer *leaf;
254    struct btrfs_ordered_sum *sums;
255    struct btrfs_sector_sum *sector_sum;
256    struct btrfs_csum_item *item;
257    unsigned long offset;
258    int ret;
259    size_t size;
260    u64 csum_end;
261    u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
262
263    path = btrfs_alloc_path();
264    BUG_ON(!path);
265
266    key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
267    key.offset = start;
268    key.type = BTRFS_EXTENT_CSUM_KEY;
269
270    ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
271    if (ret < 0)
272        goto fail;
273    if (ret > 0 && path->slots[0] > 0) {
274        leaf = path->nodes[0];
275        btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
276        if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
277            key.type == BTRFS_EXTENT_CSUM_KEY) {
278            offset = (start - key.offset) >>
279                 root->fs_info->sb->s_blocksize_bits;
280            if (offset * csum_size <
281                btrfs_item_size_nr(leaf, path->slots[0] - 1))
282                path->slots[0]--;
283        }
284    }
285
286    while (start <= end) {
287        leaf = path->nodes[0];
288        if (path->slots[0] >= btrfs_header_nritems(leaf)) {
289            ret = btrfs_next_leaf(root, path);
290            if (ret < 0)
291                goto fail;
292            if (ret > 0)
293                break;
294            leaf = path->nodes[0];
295        }
296
297        btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
298        if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
299            key.type != BTRFS_EXTENT_CSUM_KEY)
300            break;
301
302        btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
303        if (key.offset > end)
304            break;
305
306        if (key.offset > start)
307            start = key.offset;
308
309        size = btrfs_item_size_nr(leaf, path->slots[0]);
310        csum_end = key.offset + (size / csum_size) * root->sectorsize;
311        if (csum_end <= start) {
312            path->slots[0]++;
313            continue;
314        }
315
316        csum_end = min(csum_end, end + 1);
317        item = btrfs_item_ptr(path->nodes[0], path->slots[0],
318                      struct btrfs_csum_item);
319        while (start < csum_end) {
320            size = min_t(size_t, csum_end - start,
321                    MAX_ORDERED_SUM_BYTES(root));
322            sums = kzalloc(btrfs_ordered_sum_size(root, size),
323                    GFP_NOFS);
324            BUG_ON(!sums);
325
326            sector_sum = sums->sums;
327            sums->bytenr = start;
328            sums->len = size;
329
330            offset = (start - key.offset) >>
331                root->fs_info->sb->s_blocksize_bits;
332            offset *= csum_size;
333
334            while (size > 0) {
335                read_extent_buffer(path->nodes[0],
336                        &sector_sum->sum,
337                        ((unsigned long)item) +
338                        offset, csum_size);
339                sector_sum->bytenr = start;
340
341                size -= root->sectorsize;
342                start += root->sectorsize;
343                offset += csum_size;
344                sector_sum++;
345            }
346            list_add_tail(&sums->list, list);
347        }
348        path->slots[0]++;
349    }
350    ret = 0;
351fail:
352    btrfs_free_path(path);
353    return ret;
354}
355
356int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
357               struct bio *bio, u64 file_start, int contig)
358{
359    struct btrfs_ordered_sum *sums;
360    struct btrfs_sector_sum *sector_sum;
361    struct btrfs_ordered_extent *ordered;
362    char *data;
363    struct bio_vec *bvec = bio->bi_io_vec;
364    int bio_index = 0;
365    unsigned long total_bytes = 0;
366    unsigned long this_sum_bytes = 0;
367    u64 offset;
368    u64 disk_bytenr;
369
370    WARN_ON(bio->bi_vcnt <= 0);
371    sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
372    if (!sums)
373        return -ENOMEM;
374
375    sector_sum = sums->sums;
376    disk_bytenr = (u64)bio->bi_sector << 9;
377    sums->len = bio->bi_size;
378    INIT_LIST_HEAD(&sums->list);
379
380    if (contig)
381        offset = file_start;
382    else
383        offset = page_offset(bvec->bv_page) + bvec->bv_offset;
384
385    ordered = btrfs_lookup_ordered_extent(inode, offset);
386    BUG_ON(!ordered);
387    sums->bytenr = ordered->start;
388
389    while (bio_index < bio->bi_vcnt) {
390        if (!contig)
391            offset = page_offset(bvec->bv_page) + bvec->bv_offset;
392
393        if (!contig && (offset >= ordered->file_offset + ordered->len ||
394            offset < ordered->file_offset)) {
395            unsigned long bytes_left;
396            sums->len = this_sum_bytes;
397            this_sum_bytes = 0;
398            btrfs_add_ordered_sum(inode, ordered, sums);
399            btrfs_put_ordered_extent(ordered);
400
401            bytes_left = bio->bi_size - total_bytes;
402
403            sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
404                       GFP_NOFS);
405            BUG_ON(!sums);
406            sector_sum = sums->sums;
407            sums->len = bytes_left;
408            ordered = btrfs_lookup_ordered_extent(inode, offset);
409            BUG_ON(!ordered);
410            sums->bytenr = ordered->start;
411        }
412
413        data = kmap_atomic(bvec->bv_page, KM_USER0);
414        sector_sum->sum = ~(u32)0;
415        sector_sum->sum = btrfs_csum_data(root,
416                          data + bvec->bv_offset,
417                          sector_sum->sum,
418                          bvec->bv_len);
419        kunmap_atomic(data, KM_USER0);
420        btrfs_csum_final(sector_sum->sum,
421                 (char *)&sector_sum->sum);
422        sector_sum->bytenr = disk_bytenr;
423
424        sector_sum++;
425        bio_index++;
426        total_bytes += bvec->bv_len;
427        this_sum_bytes += bvec->bv_len;
428        disk_bytenr += bvec->bv_len;
429        offset += bvec->bv_len;
430        bvec++;
431    }
432    this_sum_bytes = 0;
433    btrfs_add_ordered_sum(inode, ordered, sums);
434    btrfs_put_ordered_extent(ordered);
435    return 0;
436}
437
438/*
439 * helper function for csum removal, this expects the
440 * key to describe the csum pointed to by the path, and it expects
441 * the csum to overlap the range [bytenr, len]
442 *
443 * The csum should not be entirely contained in the range and the
444 * range should not be entirely contained in the csum.
445 *
446 * This calls btrfs_truncate_item with the correct args based on the
447 * overlap, and fixes up the key as required.
448 */
449static noinline int truncate_one_csum(struct btrfs_trans_handle *trans,
450                      struct btrfs_root *root,
451                      struct btrfs_path *path,
452                      struct btrfs_key *key,
453                      u64 bytenr, u64 len)
454{
455    struct extent_buffer *leaf;
456    u16 csum_size =
457        btrfs_super_csum_size(&root->fs_info->super_copy);
458    u64 csum_end;
459    u64 end_byte = bytenr + len;
460    u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
461    int ret;
462
463    leaf = path->nodes[0];
464    csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
465    csum_end <<= root->fs_info->sb->s_blocksize_bits;
466    csum_end += key->offset;
467
468    if (key->offset < bytenr && csum_end <= end_byte) {
469        /*
470         * [ bytenr - len ]
471         * [ ]
472         * [csum ]
473         * A simple truncate off the end of the item
474         */
475        u32 new_size = (bytenr - key->offset) >> blocksize_bits;
476        new_size *= csum_size;
477        ret = btrfs_truncate_item(trans, root, path, new_size, 1);
478        BUG_ON(ret);
479    } else if (key->offset >= bytenr && csum_end > end_byte &&
480           end_byte > key->offset) {
481        /*
482         * [ bytenr - len ]
483         * [ ]
484         * [csum ]
485         * we need to truncate from the beginning of the csum
486         */
487        u32 new_size = (csum_end - end_byte) >> blocksize_bits;
488        new_size *= csum_size;
489
490        ret = btrfs_truncate_item(trans, root, path, new_size, 0);
491        BUG_ON(ret);
492
493        key->offset = end_byte;
494        ret = btrfs_set_item_key_safe(trans, root, path, key);
495        BUG_ON(ret);
496    } else {
497        BUG();
498    }
499    return 0;
500}
501
502/*
503 * deletes the csum items from the csum tree for a given
504 * range of bytes.
505 */
506int btrfs_del_csums(struct btrfs_trans_handle *trans,
507            struct btrfs_root *root, u64 bytenr, u64 len)
508{
509    struct btrfs_path *path;
510    struct btrfs_key key;
511    u64 end_byte = bytenr + len;
512    u64 csum_end;
513    struct extent_buffer *leaf;
514    int ret;
515    u16 csum_size =
516        btrfs_super_csum_size(&root->fs_info->super_copy);
517    int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
518
519    root = root->fs_info->csum_root;
520
521    path = btrfs_alloc_path();
522
523    while (1) {
524        key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
525        key.offset = end_byte - 1;
526        key.type = BTRFS_EXTENT_CSUM_KEY;
527
528        path->leave_spinning = 1;
529        ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
530        if (ret > 0) {
531            if (path->slots[0] == 0)
532                goto out;
533            path->slots[0]--;
534        }
535        leaf = path->nodes[0];
536        btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
537
538        if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
539            key.type != BTRFS_EXTENT_CSUM_KEY) {
540            break;
541        }
542
543        if (key.offset >= end_byte)
544            break;
545
546        csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
547        csum_end <<= blocksize_bits;
548        csum_end += key.offset;
549
550        /* this csum ends before we start, we're done */
551        if (csum_end <= bytenr)
552            break;
553
554        /* delete the entire item, it is inside our range */
555        if (key.offset >= bytenr && csum_end <= end_byte) {
556            ret = btrfs_del_item(trans, root, path);
557            BUG_ON(ret);
558            if (key.offset == bytenr)
559                break;
560        } else if (key.offset < bytenr && csum_end > end_byte) {
561            unsigned long offset;
562            unsigned long shift_len;
563            unsigned long item_offset;
564            /*
565             * [ bytenr - len ]
566             * [csum ]
567             *
568             * Our bytes are in the middle of the csum,
569             * we need to split this item and insert a new one.
570             *
571             * But we can't drop the path because the
572             * csum could change, get removed, extended etc.
573             *
574             * The trick here is the max size of a csum item leaves
575             * enough room in the tree block for a single
576             * item header. So, we split the item in place,
577             * adding a new header pointing to the existing
578             * bytes. Then we loop around again and we have
579             * a nicely formed csum item that we can neatly
580             * truncate.
581             */
582            offset = (bytenr - key.offset) >> blocksize_bits;
583            offset *= csum_size;
584
585            shift_len = (len >> blocksize_bits) * csum_size;
586
587            item_offset = btrfs_item_ptr_offset(leaf,
588                                path->slots[0]);
589
590            memset_extent_buffer(leaf, 0, item_offset + offset,
591                         shift_len);
592            key.offset = bytenr;
593
594            /*
595             * btrfs_split_item returns -EAGAIN when the
596             * item changed size or key
597             */
598            ret = btrfs_split_item(trans, root, path, &key, offset);
599            BUG_ON(ret && ret != -EAGAIN);
600
601            key.offset = end_byte - 1;
602        } else {
603            ret = truncate_one_csum(trans, root, path,
604                        &key, bytenr, len);
605            BUG_ON(ret);
606            if (key.offset < bytenr)
607                break;
608        }
609        btrfs_release_path(root, path);
610    }
611out:
612    btrfs_free_path(path);
613    return 0;
614}
615
616int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
617               struct btrfs_root *root,
618               struct btrfs_ordered_sum *sums)
619{
620    u64 bytenr;
621    int ret;
622    struct btrfs_key file_key;
623    struct btrfs_key found_key;
624    u64 next_offset;
625    u64 total_bytes = 0;
626    int found_next;
627    struct btrfs_path *path;
628    struct btrfs_csum_item *item;
629    struct btrfs_csum_item *item_end;
630    struct extent_buffer *leaf = NULL;
631    u64 csum_offset;
632    struct btrfs_sector_sum *sector_sum;
633    u32 nritems;
634    u32 ins_size;
635    char *eb_map;
636    char *eb_token;
637    unsigned long map_len;
638    unsigned long map_start;
639    u16 csum_size =
640        btrfs_super_csum_size(&root->fs_info->super_copy);
641
642    path = btrfs_alloc_path();
643    BUG_ON(!path);
644    sector_sum = sums->sums;
645again:
646    next_offset = (u64)-1;
647    found_next = 0;
648    file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
649    file_key.offset = sector_sum->bytenr;
650    bytenr = sector_sum->bytenr;
651    btrfs_set_key_type(&file_key, BTRFS_EXTENT_CSUM_KEY);
652
653    item = btrfs_lookup_csum(trans, root, path, sector_sum->bytenr, 1);
654    if (!IS_ERR(item)) {
655        leaf = path->nodes[0];
656        ret = 0;
657        goto found;
658    }
659    ret = PTR_ERR(item);
660    if (ret == -EFBIG) {
661        u32 item_size;
662        /* we found one, but it isn't big enough yet */
663        leaf = path->nodes[0];
664        item_size = btrfs_item_size_nr(leaf, path->slots[0]);
665        if ((item_size / csum_size) >=
666            MAX_CSUM_ITEMS(root, csum_size)) {
667            /* already at max size, make a new one */
668            goto insert;
669        }
670    } else {
671        int slot = path->slots[0] + 1;
672        /* we didn't find a csum item, insert one */
673        nritems = btrfs_header_nritems(path->nodes[0]);
674        if (path->slots[0] >= nritems - 1) {
675            ret = btrfs_next_leaf(root, path);
676            if (ret == 1)
677                found_next = 1;
678            if (ret != 0)
679                goto insert;
680            slot = 0;
681        }
682        btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
683        if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
684            found_key.type != BTRFS_EXTENT_CSUM_KEY) {
685            found_next = 1;
686            goto insert;
687        }
688        next_offset = found_key.offset;
689        found_next = 1;
690        goto insert;
691    }
692
693    /*
694     * at this point, we know the tree has an item, but it isn't big
695     * enough yet to put our csum in. Grow it
696     */
697    btrfs_release_path(root, path);
698    ret = btrfs_search_slot(trans, root, &file_key, path,
699                csum_size, 1);
700    if (ret < 0)
701        goto fail_unlock;
702
703    if (ret > 0) {
704        if (path->slots[0] == 0)
705            goto insert;
706        path->slots[0]--;
707    }
708
709    leaf = path->nodes[0];
710    btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
711    csum_offset = (bytenr - found_key.offset) >>
712            root->fs_info->sb->s_blocksize_bits;
713
714    if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
715        found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
716        csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
717        goto insert;
718    }
719
720    if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
721        csum_size) {
722        u32 diff = (csum_offset + 1) * csum_size;
723
724        /*
725         * is the item big enough already? we dropped our lock
726         * before and need to recheck
727         */
728        if (diff < btrfs_item_size_nr(leaf, path->slots[0]))
729            goto csum;
730
731        diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
732        if (diff != csum_size)
733            goto insert;
734
735        ret = btrfs_extend_item(trans, root, path, diff);
736        BUG_ON(ret);
737        goto csum;
738    }
739
740insert:
741    btrfs_release_path(root, path);
742    csum_offset = 0;
743    if (found_next) {
744        u64 tmp = total_bytes + root->sectorsize;
745        u64 next_sector = sector_sum->bytenr;
746        struct btrfs_sector_sum *next = sector_sum + 1;
747
748        while (tmp < sums->len) {
749            if (next_sector + root->sectorsize != next->bytenr)
750                break;
751            tmp += root->sectorsize;
752            next_sector = next->bytenr;
753            next++;
754        }
755        tmp = min(tmp, next_offset - file_key.offset);
756        tmp >>= root->fs_info->sb->s_blocksize_bits;
757        tmp = max((u64)1, tmp);
758        tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root, csum_size));
759        ins_size = csum_size * tmp;
760    } else {
761        ins_size = csum_size;
762    }
763    path->leave_spinning = 1;
764    ret = btrfs_insert_empty_item(trans, root, path, &file_key,
765                      ins_size);
766    path->leave_spinning = 0;
767    if (ret < 0)
768        goto fail_unlock;
769    if (ret != 0) {
770        WARN_ON(1);
771        goto fail_unlock;
772    }
773csum:
774    leaf = path->nodes[0];
775    item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
776    ret = 0;
777    item = (struct btrfs_csum_item *)((unsigned char *)item +
778                      csum_offset * csum_size);
779found:
780    item_end = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
781    item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
782                      btrfs_item_size_nr(leaf, path->slots[0]));
783    eb_token = NULL;
784next_sector:
785
786    if (!eb_token ||
787       (unsigned long)item + csum_size >= map_start + map_len) {
788        int err;
789
790        if (eb_token)
791            unmap_extent_buffer(leaf, eb_token, KM_USER1);
792        eb_token = NULL;
793        err = map_private_extent_buffer(leaf, (unsigned long)item,
794                        csum_size,
795                        &eb_token, &eb_map,
796                        &map_start, &map_len, KM_USER1);
797        if (err)
798            eb_token = NULL;
799    }
800    if (eb_token) {
801        memcpy(eb_token + ((unsigned long)item & (PAGE_CACHE_SIZE - 1)),
802               &sector_sum->sum, csum_size);
803    } else {
804        write_extent_buffer(leaf, &sector_sum->sum,
805                    (unsigned long)item, csum_size);
806    }
807
808    total_bytes += root->sectorsize;
809    sector_sum++;
810    if (total_bytes < sums->len) {
811        item = (struct btrfs_csum_item *)((char *)item +
812                          csum_size);
813        if (item < item_end && bytenr + PAGE_CACHE_SIZE ==
814            sector_sum->bytenr) {
815            bytenr = sector_sum->bytenr;
816            goto next_sector;
817        }
818    }
819    if (eb_token) {
820        unmap_extent_buffer(leaf, eb_token, KM_USER1);
821        eb_token = NULL;
822    }
823    btrfs_mark_buffer_dirty(path->nodes[0]);
824    if (total_bytes < sums->len) {
825        btrfs_release_path(root, path);
826        cond_resched();
827        goto again;
828    }
829out:
830    btrfs_free_path(path);
831    return ret;
832
833fail_unlock:
834    goto out;
835}
836

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