fs/btrfs/file-item.c

   1 #include <linux/module.h>
   2 #include "ctree.h"
   3 #include "disk-io.h"
   4 #include "transaction.h"
   5
   6 #define MAX_CSUM_ITEMS(r) ((((BTRFS_LEAF_DATA_SIZE(r) - \
   7                                  sizeof(struct btrfs_item) * 2) / \
   8                                 sizeof(struct btrfs_csum_item)) - 1))
   9 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
  10                                struct btrfs_root *root,
  11                                u64 objectid, u64 pos,
  12                                u64 offset, u64 num_blocks)
  13 {
  14         int ret = 0;
  15         struct btrfs_file_extent_item *item;
  16         struct btrfs_key file_key;
  17         struct btrfs_path *path;
  18
  19         path = btrfs_alloc_path();
  20         BUG_ON(!path);
  21         btrfs_init_path(path);
  22         file_key.objectid = objectid;
  23         file_key.offset = pos;
  24         file_key.flags = 0;
  25         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
  26
  27         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
  28                                       sizeof(*item));
  29         BUG_ON(ret);
  30         item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
  31                               struct btrfs_file_extent_item);
  32         btrfs_set_file_extent_disk_blocknr(item, offset);
  33         btrfs_set_file_extent_disk_num_blocks(item, num_blocks);
  34         btrfs_set_file_extent_offset(item, 0);
  35         btrfs_set_file_extent_num_blocks(item, num_blocks);
  36         btrfs_set_file_extent_generation(item, trans->transid);
  37         btrfs_mark_buffer_dirty(path->nodes[0]);
  38
  39         btrfs_release_path(root, path);
  40         btrfs_free_path(path);
  41         return 0;
  42 }
  43
  44 struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
  45                                           struct btrfs_root *root,
  46                                           struct btrfs_path *path,
  47                                           u64 objectid, u64 offset,
  48                                           int cow)
  49 {
  50         int ret;
  51         struct btrfs_key file_key;
  52         struct btrfs_key found_key;
  53         struct btrfs_csum_item *item;
  54         struct btrfs_leaf *leaf;
  55         u64 csum_offset = 0;
  56         int csums_in_item;
  57
  58         file_key.objectid = objectid;
  59         file_key.offset = offset;
  60         file_key.flags = 0;
  61         btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
  62         ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
  63         if (ret < 0)
  64                 goto fail;
  65         leaf = btrfs_buffer_leaf(path->nodes[0]);
  66         if (ret > 0) {
  67                 ret = 1;
  68                 if (path->slots[0] == 0)
  69                         goto fail;
  70                 path->slots[0]--;
  71                 btrfs_disk_key_to_cpu(&found_key,
  72                                       &leaf->items[path->slots[0]].key);
  73                 if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
  74                     found_key.objectid != objectid) {
  75                         goto fail;
  76                 }
  77                 csum_offset = (offset - found_key.offset) >>
  78                                 root->fs_info->sb->s_blocksize_bits;
  79                 csums_in_item = btrfs_item_size(leaf->items + path->slots[0]);
  80                 csums_in_item /= sizeof(struct btrfs_csum_item);
  81
  82                 if (csum_offset >= csums_in_item) {
  83                         ret = -EFBIG;
  84                         goto fail;
  85                 }
  86         }
  87         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
  88         item += csum_offset;
  89         return item;
  90 fail:
  91         if (ret > 0)
  92                 ret = -ENOENT;
  93         return ERR_PTR(ret);
  94 }
  95
  96
  97 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
  98                              struct btrfs_root *root,
  99                              struct btrfs_path *path, u64 objectid,
 100                              u64 offset, int mod)
 101 {
 102         int ret;
 103         struct btrfs_key file_key;
 104         int ins_len = mod < 0 ? -1 : 0;
 105         int cow = mod != 0;
 106
 107         file_key.objectid = objectid;
 108         file_key.offset = offset;
 109         file_key.flags = 0;
 110         btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
 111         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 112         return ret;
 113 }
 114
 115 int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
 116                           struct btrfs_root *root,
 117                           u64 objectid, u64 offset,
 118                           char *data, size_t len)
 119 {
 120         int ret;
 121         struct btrfs_key file_key;
 122         struct btrfs_key found_key;
 123         struct btrfs_path *path;
 124         struct btrfs_csum_item *item;
 125         struct btrfs_leaf *leaf;
 126         u64 csum_offset;
 127
 128         path = btrfs_alloc_path();
 129         BUG_ON(!path);
 130
 131         file_key.objectid = objectid;
 132         file_key.offset = offset;
 133         file_key.flags = 0;
 134         btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
 135
 136         item = btrfs_lookup_csum(trans, root, path, objectid, offset, 1);
 137         if (!IS_ERR(item))
 138                 goto found;
 139         ret = PTR_ERR(item);
 140         if (ret == -EFBIG) {
 141                 u32 item_size;
 142                 /* we found one, but it isn't big enough yet */
 143                 leaf = btrfs_buffer_leaf(path->nodes[0]);
 144                 item_size = btrfs_item_size(leaf->items + path->slots[0]);
 145                 if ((item_size / sizeof(struct btrfs_csum_item)) >=
 146                     MAX_CSUM_ITEMS(root)) {
 147                         /* already at max size, make a new one */
 148                         goto insert;
 149                 }
 150         } else {
 151                 /* we didn't find a csum item, insert one */
 152                 goto insert;
 153         }
 154
 155         /*
 156          * at this point, we know the tree has an item, but it isn't big
 157          * enough yet to put our csum in.  Grow it
 158          */
 159         btrfs_release_path(root, path);
 160         ret = btrfs_search_slot(trans, root, &file_key, path,
 161                                 sizeof(struct btrfs_csum_item), 1);
 162         if (ret < 0)
 163                 goto fail;
 164         if (ret == 0) {
 165                 BUG();
 166         }
 167         if (path->slots[0] == 0) {
 168                 goto insert;
 169         }
 170         path->slots[0]--;
 171         leaf = btrfs_buffer_leaf(path->nodes[0]);
 172         btrfs_disk_key_to_cpu(&found_key, &leaf->items[path->slots[0]].key);
 173         csum_offset = (offset - found_key.offset) >>
 174                         root->fs_info->sb->s_blocksize_bits;
 175         if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
 176             found_key.objectid != objectid ||
 177             csum_offset >= MAX_CSUM_ITEMS(root)) {
 178                 WARN_ON(1);
 179                 goto insert;
 180         }
 181         if (csum_offset >= btrfs_item_size(leaf->items + path->slots[0]) /
 182             sizeof(struct btrfs_csum_item)) {
 183                 u32 diff = (csum_offset + 1) * sizeof(struct btrfs_csum_item);
 184                 diff = diff - btrfs_item_size(leaf->items + path->slots[0]);
 185                 WARN_ON(diff != sizeof(struct btrfs_csum_item));
 186                 ret = btrfs_extend_item(trans, root, path, diff);
 187                 BUG_ON(ret);
 188                 goto csum;
 189         }
 190
 191 insert:
 192         btrfs_release_path(root, path);
 193         csum_offset = 0;
 194         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 195                                       sizeof(struct btrfs_csum_item));
 196         if (ret != 0) {
 197                 printk("at insert for %Lu %u %Lu ret is %d\n", file_key.objectid, file_key.flags, file_key.offset, ret);
 198                 WARN_ON(1);
 199                 goto fail;
 200         }
 201 csum:
 202         item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
 203                               struct btrfs_csum_item);
 204         ret = 0;
 205         item += csum_offset;
 206 found:
 207         btrfs_check_bounds(item->csum, BTRFS_CSUM_SIZE, path->nodes[0]->b_data, root->fs_info->sb->s_blocksize);
 208         ret = btrfs_csum_data(root, data, len, item->csum);
 209         btrfs_mark_buffer_dirty(path->nodes[0]);
 210 fail:
 211         btrfs_release_path(root, path);
 212         btrfs_free_path(path);
 213         return ret;
 214 }
 215
 216 int btrfs_csum_verify_file_block(struct btrfs_root *root,
 217                                  u64 objectid, u64 offset,
 218                                  char *data, size_t len)
 219 {
 220         int ret;
 221         struct btrfs_key file_key;
 222         struct btrfs_path *path;
 223         struct btrfs_csum_item *item;
 224         char result[BTRFS_CSUM_SIZE];
 225
 226         path = btrfs_alloc_path();
 227         BUG_ON(!path);
 228         btrfs_init_path(path);
 229         file_key.objectid = objectid;
 230         file_key.offset = offset;
 231         file_key.flags = 0;
 232         btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
 233         mutex_lock(&root->fs_info->fs_mutex);
 234
 235         item = btrfs_lookup_csum(NULL, root, path, objectid, offset, 0);
 236         if (IS_ERR(item)) {
 237                 ret = PTR_ERR(item);
 238                 /* a csum that isn't present is a preallocated region. */
 239                 if (ret == -ENOENT || ret == -EFBIG)
 240                         ret = 1;
 241                 goto fail;
 242         }
 243
 244         ret = btrfs_csum_data(root, data, len, result);
 245         WARN_ON(ret);
 246         if (memcmp(result, item->csum, BTRFS_CSUM_SIZE))
 247                 ret = 1;
 248 fail:
 249         btrfs_release_path(root, path);
 250         btrfs_free_path(path);
 251         mutex_unlock(&root->fs_info->fs_mutex);
 252         return ret;
 253 }
 254