SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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 "ctree.h"
  20 #include "disk-io.h"
  21 #include "transaction.h"
  22 #include "print-tree.h"
  23
  24 #define MAX_CSUM_ITEMS(r) ((((BTRFS_LEAF_DATA_SIZE(r) - \
  25                                sizeof(struct btrfs_item) * 2) / \
  26                                BTRFS_CRC32_SIZE) - 1))
  27 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
  28                                struct btrfs_root *root,
  29                                u64 objectid, u64 pos,
  30                                u64 offset, u64 disk_num_bytes,
  31                                u64 num_bytes)
  32 {
  33         int ret = 0;
  34         struct btrfs_file_extent_item *item;
  35         struct btrfs_key file_key;
  36         struct btrfs_path *path;
  37         struct extent_buffer *leaf;
  38
  39         path = btrfs_alloc_path();
  40         BUG_ON(!path);
  41         file_key.objectid = objectid;
  42         file_key.offset = pos;
  43         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
  44
  45         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
  46                                       sizeof(*item));
  47         if (ret < 0)
  48                 goto out;
  49         BUG_ON(ret);
  50         leaf = path->nodes[0];
  51         item = btrfs_item_ptr(leaf, path->slots[0],
  52                               struct btrfs_file_extent_item);
  53         btrfs_set_file_extent_disk_bytenr(leaf, item, offset);
  54         btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
  55         btrfs_set_file_extent_offset(leaf, item, 0);
  56         btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
  57         btrfs_set_file_extent_generation(leaf, item, trans->transid);
  58         btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
  59         btrfs_mark_buffer_dirty(leaf);
  60 out:
  61         btrfs_free_path(path);
  62         return ret;
  63 }
  64
  65 struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
  66                                           struct btrfs_root *root,
  67                                           struct btrfs_path *path,
  68                                           u64 objectid, u64 offset,
  69                                           int cow)
  70 {
  71         int ret;
  72         struct btrfs_key file_key;
  73         struct btrfs_key found_key;
  74         struct btrfs_csum_item *item;
  75         struct extent_buffer *leaf;
  76         u64 csum_offset = 0;
  77         int csums_in_item;
  78
  79         file_key.objectid = objectid;
  80         file_key.offset = offset;
  81         btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
  82         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
  83         if (ret < 0)
  84                 goto fail;
  85         leaf = path->nodes[0];
  86         if (ret > 0) {
  87                 ret = 1;
  88                 if (path->slots[0] == 0)
  89                         goto fail;
  90                 path->slots[0]--;
  91                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
  92                 if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
  93                     found_key.objectid != objectid) {
  94                         goto fail;
  95                 }
  96                 csum_offset = (offset - found_key.offset) >>
  97                                 root->fs_info->sb->s_blocksize_bits;
  98                 csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
  99                 csums_in_item /= BTRFS_CRC32_SIZE;
 100
 101                 if (csum_offset >= csums_in_item) {
 102                         ret = -EFBIG;
 103                         goto fail;
 104                 }
 105         }
 106         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 107         item = (struct btrfs_csum_item *)((unsigned char *)item +
 108                                           csum_offset * BTRFS_CRC32_SIZE);
 109         return item;
 110 fail:
 111         if (ret > 0)
 112                 ret = -ENOENT;
 113         return ERR_PTR(ret);
 114 }
 115
 116
 117 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 118                              struct btrfs_root *root,
 119                              struct btrfs_path *path, u64 objectid,
 120                              u64 offset, int mod)
 121 {
 122         int ret;
 123         struct btrfs_key file_key;
 124         int ins_len = mod < 0 ? -1 : 0;
 125         int cow = mod != 0;
 126
 127         file_key.objectid = objectid;
 128         file_key.offset = offset;
 129         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
 130         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 131         return ret;
 132 }
 133
 134 int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
 135                           struct btrfs_root *root,
 136                           struct inode *inode,
 137                           u64 objectid, u64 offset,
 138                           char *data, size_t len)
 139 {
 140         int ret;
 141         struct btrfs_key file_key;
 142         struct btrfs_key found_key;
 143         u64 next_offset = (u64)-1;
 144         int found_next = 0;
 145         struct btrfs_path *path;
 146         struct btrfs_csum_item *item;
 147         struct extent_buffer *leaf = NULL;
 148         u64 csum_offset;
 149         u32 csum_result = ~(u32)0;
 150         u32 nritems;
 151         u32 ins_size;
 152
 153         path = btrfs_alloc_path();
 154         BUG_ON(!path);
 155
 156         file_key.objectid = objectid;
 157         file_key.offset = offset;
 158         btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
 159
 160         item = btrfs_lookup_csum(trans, root, path, objectid, offset, 1);
 161         if (!IS_ERR(item)) {
 162                 leaf = path->nodes[0];
 163                 goto found;
 164         }
 165         ret = PTR_ERR(item);
 166         if (ret == -EFBIG) {
 167                 u32 item_size;
 168                 /* we found one, but it isn't big enough yet */
 169                 leaf = path->nodes[0];
 170                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
 171                 if ((item_size / BTRFS_CRC32_SIZE) >= MAX_CSUM_ITEMS(root)) {
 172                         /* already at max size, make a new one */
 173                         goto insert;
 174                 }
 175         } else {
 176                 int slot = path->slots[0] + 1;
 177                 /* we didn't find a csum item, insert one */
 178                 nritems = btrfs_header_nritems(path->nodes[0]);
 179                 if (path->slots[0] >= nritems - 1) {
 180                         ret = btrfs_next_leaf(root, path);
 181                         if (ret == 1) {
 182                                 found_next = 1;
 183                         } else if (ret == 0) {
 184                                 slot = 0;
 185                         } else {
 186                                 goto insert;
 187                         }
 188                 }
 189                 btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
 190                 if (found_key.objectid != objectid ||
 191                     found_key.type != BTRFS_CSUM_ITEM_KEY) {
 192                         found_next = 1;
 193                         goto insert;
 194                 }
 195                 next_offset = found_key.offset;
 196                 found_next = 1;
 197                 goto insert;
 198         }
 199
 200         /*
 201          * at this point, we know the tree has an item, but it isn't big
 202          * enough yet to put our csum in.  Grow it
 203          */
 204         btrfs_release_path(root, path);
 205         ret = btrfs_search_slot(trans, root, &file_key, path,
 206                                 BTRFS_CRC32_SIZE, 1);
 207         if (ret < 0)
 208                 goto fail;
 209         if (ret == 0) {
 210                 BUG();
 211         }
 212         if (path->slots[0] == 0) {
 213                 goto insert;
 214         }
 215         path->slots[0]--;
 216         leaf = path->nodes[0];
 217         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 218         csum_offset = (offset - found_key.offset) >>
 219                         root->fs_info->sb->s_blocksize_bits;
 220         if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
 221             found_key.objectid != objectid ||
 222             csum_offset >= MAX_CSUM_ITEMS(root)) {
 223                 goto insert;
 224         }
 225         if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
 226             BTRFS_CRC32_SIZE) {
 227                 u32 diff = (csum_offset + 1) * BTRFS_CRC32_SIZE;
 228                 diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
 229                 if (diff != BTRFS_CRC32_SIZE)
 230                         goto insert;
 231                 ret = btrfs_extend_item(trans, root, path, diff);
 232                 BUG_ON(ret);
 233                 goto csum;
 234         }
 235
 236 insert:
 237         btrfs_release_path(root, path);
 238         csum_offset = 0;
 239         if (found_next) {
 240                 u64 tmp = min((u64)i_size_read(inode), next_offset);
 241                 tmp -= offset + root->sectorsize - 1;
 242                 tmp >>= root->fs_info->sb->s_blocksize_bits;
 243                 tmp = max((u64)1, tmp);
 244                 tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root));
 245                 ins_size = BTRFS_CRC32_SIZE * tmp;
 246         } else {
 247                 ins_size = BTRFS_CRC32_SIZE;
 248         }
 249         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 250                                       ins_size);
 251         if (ret < 0)
 252                 goto fail;
 253         if (ret != 0) {
 254                 WARN_ON(1);
 255                 goto fail;
 256         }
 257 csum:
 258         leaf = path->nodes[0];
 259         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 260         ret = 0;
 261         item = (struct btrfs_csum_item *)((unsigned char *)item +
 262                                           csum_offset * BTRFS_CRC32_SIZE);
 263 found:
 264         csum_result = btrfs_csum_data(root, data, csum_result, len);
 265         btrfs_csum_final(csum_result, (char *)&csum_result);
 266         write_extent_buffer(leaf, &csum_result, (unsigned long)item,
 267                             BTRFS_CRC32_SIZE);
 268         btrfs_mark_buffer_dirty(path->nodes[0]);
 269 fail:
 270         btrfs_release_path(root, path);
 271         btrfs_free_path(path);
 272         return ret;
 273 }
 274
 275 int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
 276                         struct btrfs_root *root, struct btrfs_path *path,
 277                         u64 isize)
 278 {
 279         struct btrfs_key key;
 280         struct extent_buffer *leaf = path->nodes[0];
 281         int slot = path->slots[0];
 282         int ret;
 283         u32 new_item_size;
 284         u64 new_item_span;
 285         u64 blocks;
 286
 287         btrfs_item_key_to_cpu(leaf, &key, slot);
 288         if (isize <= key.offset)
 289                 return 0;
 290         new_item_span = isize - key.offset;
 291         blocks = (new_item_span + root->sectorsize - 1) >>
 292                 root->fs_info->sb->s_blocksize_bits;
 293         new_item_size = blocks * BTRFS_CRC32_SIZE;
 294         if (new_item_size >= btrfs_item_size_nr(leaf, slot))
 295                 return 0;
 296         ret = btrfs_truncate_item(trans, root, path, new_item_size);
 297         BUG_ON(ret);
 298         return ret;
 299 }
 300