fs/btrfs/super.c

   1 #include <linux/module.h>
   2 #include <linux/buffer_head.h>
   3 #include <linux/fs.h>
   4 #include <linux/pagemap.h>
   5 #include <linux/highmem.h>
   6 #include <linux/time.h>
   7 #include <linux/init.h>
   8 #include <linux/string.h>
   9 #include <linux/smp_lock.h>
  10 #include <linux/backing-dev.h>
  11 #include <linux/mpage.h>
  12 #include "ctree.h"
  13 #include "disk-io.h"
  14 #include "transaction.h"
  15
  16 #define BTRFS_SUPER_MAGIC 0x9123682E
  17
  18 static struct inode_operations btrfs_dir_inode_operations;
  19 static struct super_operations btrfs_super_ops;
  20 static struct file_operations btrfs_dir_file_operations;
  21 static struct inode_operations btrfs_file_inode_operations;
  22 static struct address_space_operations btrfs_aops;
  23 static struct file_operations btrfs_file_operations;
  24
  25 static void btrfs_read_locked_inode(struct inode *inode)
  26 {
  27         struct btrfs_path path;
  28         struct btrfs_inode_item *inode_item;
  29         struct btrfs_root *root = btrfs_sb(inode->i_sb);
  30         int ret;
  31         btrfs_init_path(&path);
  32         ret = btrfs_lookup_inode(NULL, root, &path, inode->i_ino, 0);
  33         if (ret) {
  34                 make_bad_inode(inode);
  35                 btrfs_release_path(root, &path);
  36                 return;
  37         }
  38         inode_item = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]),
  39                                   path.slots[0],
  40                                   struct btrfs_inode_item);
  41
  42         inode->i_mode = btrfs_inode_mode(inode_item);
  43         inode->i_nlink = btrfs_inode_nlink(inode_item);
  44         inode->i_uid = btrfs_inode_uid(inode_item);
  45         inode->i_gid = btrfs_inode_gid(inode_item);
  46         inode->i_size = btrfs_inode_size(inode_item);
  47         inode->i_atime.tv_sec = btrfs_timespec_sec(&inode_item->atime);
  48         inode->i_atime.tv_nsec = btrfs_timespec_nsec(&inode_item->atime);
  49         inode->i_mtime.tv_sec = btrfs_timespec_sec(&inode_item->mtime);
  50         inode->i_mtime.tv_nsec = btrfs_timespec_nsec(&inode_item->mtime);
  51         inode->i_ctime.tv_sec = btrfs_timespec_sec(&inode_item->ctime);
  52         inode->i_ctime.tv_nsec = btrfs_timespec_nsec(&inode_item->ctime);
  53         inode->i_blocks = btrfs_inode_nblocks(inode_item);
  54         inode->i_generation = btrfs_inode_generation(inode_item);
  55         btrfs_release_path(root, &path);
  56         switch (inode->i_mode & S_IFMT) {
  57 #if 0
  58         default:
  59                 init_special_inode(inode, inode->i_mode,
  60                                    btrfs_inode_rdev(inode_item));
  61                 break;
  62 #endif
  63         case S_IFREG:
  64                 inode->i_mapping->a_ops = &btrfs_aops;
  65                 inode->i_fop = &btrfs_file_operations;
  66                 inode->i_op = &btrfs_file_inode_operations;
  67                 break;
  68         case S_IFDIR:
  69                 inode->i_op = &btrfs_dir_inode_operations;
  70                 inode->i_fop = &btrfs_dir_file_operations;
  71                 break;
  72         case S_IFLNK:
  73                 // inode->i_op = &page_symlink_inode_operations;
  74                 break;
  75         }
  76         return;
  77 }
  78
  79 static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
  80 {
  81         struct btrfs_path path;
  82         struct btrfs_root *root;
  83         struct btrfs_trans_handle *trans;
  84         const char *name = dentry->d_name.name;
  85         int name_len = dentry->d_name.len;
  86         int ret;
  87         u64 objectid;
  88         struct btrfs_dir_item *di;
  89
  90         btrfs_init_path(&path);
  91         root = btrfs_sb(dir->i_sb);
  92         mutex_lock(&root->fs_info->fs_mutex);
  93         trans = btrfs_start_transaction(root, 1);
  94
  95         ret = btrfs_lookup_dir_item(trans, root, &path, dir->i_ino,
  96                                     name, name_len, -1);
  97         if (ret < 0)
  98                 goto err;
  99         if (ret > 0) {
 100                 ret = -ENOENT;
 101                 goto err;
 102         }
 103         di = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
 104                             struct btrfs_dir_item);
 105         objectid = btrfs_dir_objectid(di);
 106
 107         ret = btrfs_del_item(trans, root, &path);
 108         BUG_ON(ret);
 109         dentry->d_inode->i_ctime = dir->i_ctime;
 110 err:
 111         btrfs_release_path(root, &path);
 112         btrfs_end_transaction(trans, root);
 113         mutex_unlock(&root->fs_info->fs_mutex);
 114         if (ret == 0)
 115                 inode_dec_link_count(dentry->d_inode);
 116         return ret;
 117 }
 118
 119 static int btrfs_free_inode(struct btrfs_trans_handle *trans,
 120                             struct btrfs_root *root,
 121                             struct inode *inode)
 122 {
 123         u64 objectid = inode->i_ino;
 124         struct btrfs_path path;
 125         struct btrfs_inode_map_item *map;
 126         struct btrfs_key stat_data_key;
 127         int ret;
 128         clear_inode(inode);
 129         btrfs_init_path(&path);
 130         ret = btrfs_lookup_inode_map(trans, root, &path, objectid, -1);
 131         if (ret) {
 132                 if (ret > 0)
 133                         ret = -ENOENT;
 134                 btrfs_release_path(root, &path);
 135                 goto error;
 136         }
 137         map = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
 138                             struct btrfs_inode_map_item);
 139         btrfs_disk_key_to_cpu(&stat_data_key, &map->key);
 140         ret = btrfs_del_item(trans, root->fs_info->inode_root, &path);
 141         BUG_ON(ret);
 142         btrfs_release_path(root, &path);
 143         btrfs_init_path(&path);
 144
 145         ret = btrfs_lookup_inode(trans, root, &path, objectid, -1);
 146         BUG_ON(ret);
 147         ret = btrfs_del_item(trans, root, &path);
 148         BUG_ON(ret);
 149         btrfs_release_path(root, &path);
 150 error:
 151         return ret;
 152 }
 153
 154 static void btrfs_delete_inode(struct inode *inode)
 155 {
 156         struct btrfs_trans_handle *trans;
 157         struct btrfs_root *root = btrfs_sb(inode->i_sb);
 158         truncate_inode_pages(&inode->i_data, 0);
 159         if (is_bad_inode(inode)) {
 160                 goto no_delete;
 161         }
 162         inode->i_size = 0;
 163         if (inode->i_blocks)
 164                 WARN_ON(1);
 165
 166         mutex_lock(&root->fs_info->fs_mutex);
 167         trans = btrfs_start_transaction(root, 1);
 168         btrfs_free_inode(trans, root, inode);
 169         btrfs_end_transaction(trans, root);
 170         mutex_unlock(&root->fs_info->fs_mutex);
 171         return;
 172 no_delete:
 173         clear_inode(inode);
 174 }
 175
 176
 177 static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry,
 178                               ino_t *ino)
 179 {
 180         const char *name = dentry->d_name.name;
 181         int namelen = dentry->d_name.len;
 182         struct btrfs_dir_item *di;
 183         struct btrfs_path path;
 184         struct btrfs_root *root = btrfs_sb(dir->i_sb);
 185         int ret;
 186
 187         btrfs_init_path(&path);
 188         ret = btrfs_lookup_dir_item(NULL, root, &path, dir->i_ino, name,
 189                                     namelen, 0);
 190         if (ret || !btrfs_match_dir_item_name(root, &path, name, namelen)) {
 191                 *ino = 0;
 192                 goto out;
 193         }
 194         di = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
 195                             struct btrfs_dir_item);
 196         *ino = btrfs_dir_objectid(di);
 197 out:
 198         btrfs_release_path(root, &path);
 199         return ret;
 200 }
 201
 202 static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
 203                                    struct nameidata *nd)
 204 {
 205         struct inode * inode;
 206         ino_t ino;
 207         int ret;
 208
 209         if (dentry->d_name.len > BTRFS_NAME_LEN)
 210                 return ERR_PTR(-ENAMETOOLONG);
 211
 212         ret = btrfs_inode_by_name(dir, dentry, &ino);
 213         if (ret < 0)
 214                 return ERR_PTR(ret);
 215         inode = NULL;
 216         if (ino) {
 217                 inode = iget(dir->i_sb, ino);
 218                 if (!inode)
 219                         return ERR_PTR(-EACCES);
 220         }
 221         return d_splice_alias(inode, dentry);
 222 }
 223
 224 static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 225 {
 226         struct inode *inode = filp->f_path.dentry->d_inode;
 227         struct btrfs_root *root = btrfs_sb(inode->i_sb);
 228         struct btrfs_item *item;
 229         struct btrfs_dir_item *di;
 230         struct btrfs_key key;
 231         struct btrfs_path path;
 232         int ret;
 233         u32 nritems;
 234         struct btrfs_leaf *leaf;
 235         int slot;
 236         int advance;
 237         unsigned char d_type = DT_UNKNOWN;
 238         int over = 0;
 239
 240         key.objectid = inode->i_ino;
 241         key.flags = 0;
 242         btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
 243         key.offset = filp->f_pos;
 244         btrfs_init_path(&path);
 245         ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
 246         if (ret < 0) {
 247                 goto err;
 248         }
 249         advance = 0;
 250         while(1) {
 251                 leaf = btrfs_buffer_leaf(path.nodes[0]);
 252                 nritems = btrfs_header_nritems(&leaf->header);
 253                 slot = path.slots[0];
 254                 if (advance || slot >= nritems) {
 255                         if (slot >= nritems -1) {
 256                                 ret = btrfs_next_leaf(root, &path);
 257                                 if (ret)
 258                                         break;
 259                                 leaf = btrfs_buffer_leaf(path.nodes[0]);
 260                                 nritems = btrfs_header_nritems(&leaf->header);
 261                                 slot = path.slots[0];
 262                         } else {
 263                                 slot++;
 264                                 path.slots[0]++;
 265                         }
 266                 }
 267                 advance = 1;
 268                 item = leaf->items + slot;
 269                 if (btrfs_disk_key_objectid(&item->key) != key.objectid)
 270                         break;
 271                 if (btrfs_disk_key_type(&item->key) != BTRFS_DIR_ITEM_KEY)
 272                         continue;
 273                 if (btrfs_disk_key_offset(&item->key) < filp->f_pos)
 274                         continue;
 275
 276                 advance = 1;
 277                 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
 278                 over = filldir(dirent, (const char *)(di + 1),
 279                                btrfs_dir_name_len(di),
 280                                btrfs_disk_key_offset(&item->key),
 281                                btrfs_dir_objectid(di), d_type);
 282                 if (over) {
 283                         filp->f_pos = btrfs_disk_key_offset(&item->key);
 284                         break;
 285                 }
 286                 filp->f_pos = btrfs_disk_key_offset(&item->key) + 1;
 287         }
 288         ret = 0;
 289 err:
 290         btrfs_release_path(root, &path);
 291         return ret;
 292 }
 293
 294 static void btrfs_put_super (struct super_block * sb)
 295 {
 296         struct btrfs_root *root = btrfs_sb(sb);
 297         int ret;
 298
 299         ret = close_ctree(root);
 300         if (ret) {
 301                 printk("close ctree returns %d\n", ret);
 302         }
 303         sb->s_fs_info = NULL;
 304 }
 305
 306 static int btrfs_fill_super(struct super_block * sb, void * data, int silent)
 307 {
 308         struct inode * inode;
 309         struct dentry * root_dentry;
 310         struct btrfs_super_block *disk_super;
 311         struct buffer_head *bh;
 312         struct btrfs_root *root;
 313
 314         sb->s_maxbytes = MAX_LFS_FILESIZE;
 315         sb->s_blocksize = PAGE_CACHE_SIZE;
 316         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 317         sb->s_magic = BTRFS_SUPER_MAGIC;
 318         sb->s_op = &btrfs_super_ops;
 319         sb->s_time_gran = 1;
 320
 321         bh = sb_bread(sb, BTRFS_SUPER_INFO_OFFSET / sb->s_blocksize);
 322         if (!bh) {
 323                 printk("btrfs: unable to read on disk super\n");
 324                 return -EIO;
 325         }
 326         disk_super = (struct btrfs_super_block *)bh->b_data;
 327         root = open_ctree(sb, bh, disk_super);
 328         sb->s_fs_info = root;
 329         if (!root) {
 330                 printk("btrfs: open_ctree failed\n");
 331                 return -EIO;
 332         }
 333         printk("read in super total blocks %Lu root %Lu\n",
 334                btrfs_super_total_blocks(disk_super),
 335                btrfs_super_root_dir(disk_super));
 336
 337         inode = iget_locked(sb, btrfs_super_root_dir(disk_super));
 338         if (!inode)
 339                 return -ENOMEM;
 340         if (inode->i_state & I_NEW) {
 341                 btrfs_read_locked_inode(inode);
 342                 unlock_new_inode(inode);
 343         }
 344
 345         root_dentry = d_alloc_root(inode);
 346         if (!root_dentry) {
 347                 iput(inode);
 348                 return -ENOMEM;
 349         }
 350         sb->s_root = root_dentry;
 351
 352         return 0;
 353 }
 354
 355 static void fill_inode_item(struct btrfs_inode_item *item,
 356                             struct inode *inode)
 357 {
 358         btrfs_set_inode_uid(item, inode->i_uid);
 359         btrfs_set_inode_gid(item, inode->i_gid);
 360         btrfs_set_inode_size(item, inode->i_size);
 361         btrfs_set_inode_mode(item, inode->i_mode);
 362         btrfs_set_inode_nlink(item, inode->i_nlink);
 363         btrfs_set_timespec_sec(&item->atime, inode->i_atime.tv_sec);
 364         btrfs_set_timespec_nsec(&item->atime, inode->i_atime.tv_nsec);
 365         btrfs_set_timespec_sec(&item->mtime, inode->i_mtime.tv_sec);
 366         btrfs_set_timespec_nsec(&item->mtime, inode->i_mtime.tv_nsec);
 367         btrfs_set_timespec_sec(&item->ctime, inode->i_ctime.tv_sec);
 368         btrfs_set_timespec_nsec(&item->ctime, inode->i_ctime.tv_nsec);
 369         btrfs_set_inode_nblocks(item, inode->i_blocks);
 370         btrfs_set_inode_generation(item, inode->i_generation);
 371 }
 372
 373 static int btrfs_update_inode(struct btrfs_trans_handle *trans,
 374                               struct btrfs_root *root,
 375                               struct inode *inode)
 376 {
 377         struct btrfs_inode_item *inode_item;
 378         struct btrfs_path path;
 379         int ret;
 380
 381         btrfs_init_path(&path);
 382
 383         ret = btrfs_lookup_inode(trans, root, &path, inode->i_ino, 1);
 384         if (ret) {
 385                 if (ret > 0)
 386                         ret = -ENOENT;
 387                 goto failed;
 388         }
 389
 390         inode_item = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]),
 391                                   path.slots[0],
 392                                   struct btrfs_inode_item);
 393
 394         fill_inode_item(inode_item, inode);
 395         mark_buffer_dirty(path.nodes[0]);
 396 failed:
 397         btrfs_release_path(root, &path);
 398         return 0;
 399 }
 400
 401 static int btrfs_write_inode(struct inode *inode, int wait)
 402 {
 403         struct btrfs_root *root = btrfs_sb(inode->i_sb);
 404         struct btrfs_trans_handle *trans;
 405         int ret;
 406
 407         mutex_lock(&root->fs_info->fs_mutex);
 408         trans = btrfs_start_transaction(root, 1);
 409         ret = btrfs_update_inode(trans, root, inode);
 410         if (wait)
 411                 btrfs_commit_transaction(trans, root);
 412         else
 413                 btrfs_end_transaction(trans, root);
 414         mutex_unlock(&root->fs_info->fs_mutex);
 415         return ret;
 416 }
 417
 418 static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 419                                      struct inode *dir, int mode)
 420 {
 421         struct inode *inode;
 422         struct btrfs_inode_item inode_item;
 423         struct btrfs_root *root = btrfs_sb(dir->i_sb);
 424         struct btrfs_key key;
 425         int ret;
 426         u64 objectid;
 427
 428         inode = new_inode(dir->i_sb);
 429         if (!inode)
 430                 return ERR_PTR(-ENOMEM);
 431
 432         ret = btrfs_find_free_objectid(trans, root, dir->i_ino, &objectid);
 433         BUG_ON(ret);
 434
 435         inode->i_uid = current->fsuid;
 436         inode->i_gid = current->fsgid;
 437         inode->i_mode = mode;
 438         inode->i_ino = objectid;
 439         inode->i_blocks = 0;
 440         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
 441         fill_inode_item(&inode_item, inode);
 442
 443         key.objectid = objectid;
 444         key.flags = 0;
 445         key.offset = 0;
 446         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
 447         ret = btrfs_insert_inode_map(trans, root, objectid, &key);
 448         BUG_ON(ret);
 449
 450         ret = btrfs_insert_inode(trans, root, objectid, &inode_item);
 451         BUG_ON(ret);
 452
 453         insert_inode_hash(inode);
 454         return inode;
 455 }
 456
 457 static int btrfs_add_link(struct btrfs_trans_handle *trans,
 458                             struct dentry *dentry, struct inode *inode)
 459 {
 460         int ret;
 461         ret = btrfs_insert_dir_item(trans, btrfs_sb(inode->i_sb),
 462                                     dentry->d_name.name, dentry->d_name.len,
 463                                     dentry->d_parent->d_inode->i_ino,
 464                                     inode->i_ino, 0);
 465         if (ret == 0) {
 466                 dentry->d_parent->d_inode->i_size += dentry->d_name.len;
 467                 ret = btrfs_update_inode(trans, btrfs_sb(inode->i_sb),
 468                                          dentry->d_parent->d_inode);
 469         }
 470
 471         return ret;
 472 }
 473
 474 static int btrfs_add_nondir(struct btrfs_trans_handle *trans,
 475                             struct dentry *dentry, struct inode *inode)
 476 {
 477         int err = btrfs_add_link(trans, dentry, inode);
 478         if (!err) {
 479                 d_instantiate(dentry, inode);
 480                 return 0;
 481         }
 482         return err;
 483 }
 484
 485 static int btrfs_create(struct inode *dir, struct dentry *dentry,
 486                         int mode, struct nameidata *nd)
 487 {
 488         struct btrfs_trans_handle *trans;
 489         struct btrfs_root *root = btrfs_sb(dir->i_sb);
 490         struct inode *inode;
 491         int err;
 492         int drop_inode = 0;
 493
 494         mutex_lock(&root->fs_info->fs_mutex);
 495         trans = btrfs_start_transaction(root, 1);
 496         inode = btrfs_new_inode(trans, dir, mode);
 497         err = PTR_ERR(inode);
 498         if (IS_ERR(inode))
 499                 goto out_unlock;
 500         // FIXME mark the inode dirty
 501         err = btrfs_add_nondir(trans, dentry, inode);
 502         if (err)
 503                 drop_inode = 1;
 504         else {
 505                 inode->i_mapping->a_ops = &btrfs_aops;
 506                 inode->i_fop = &btrfs_file_operations;
 507                 inode->i_op = &btrfs_file_inode_operations;
 508         }
 509         dir->i_sb->s_dirt = 1;
 510         btrfs_end_transaction(trans, root);
 511 out_unlock:
 512         mutex_unlock(&root->fs_info->fs_mutex);
 513         if (drop_inode) {
 514                 inode_dec_link_count(inode);
 515                 iput(inode);
 516         }
 517         return err;
 518 }
 519
 520 static int btrfs_make_empty_dir(struct btrfs_trans_handle *trans,
 521                                 struct inode *inode, struct inode *dir)
 522 {
 523         struct btrfs_root *root = btrfs_sb(inode->i_sb);
 524         int ret;
 525         char buf[2];
 526         buf[0] = '.';
 527         buf[1] = '.';
 528
 529         ret = btrfs_insert_dir_item(trans, root, buf, 1, inode->i_ino,
 530                                     inode->i_ino, 1);
 531         if (ret)
 532                 goto error;
 533         ret = btrfs_insert_dir_item(trans, root, buf, 2, inode->i_ino,
 534                                     dir->i_ino, 1);
 535         if (ret)
 536                 goto error;
 537         inode->i_size = 3;
 538         ret = btrfs_update_inode(trans, root, inode);
 539 error:
 540         return ret;
 541 }
 542
 543 static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 544 {
 545         struct inode *inode;
 546         struct btrfs_trans_handle *trans;
 547         struct btrfs_root *root = btrfs_sb(dir->i_sb);
 548         int err = 0;
 549         int drop_on_err = 0;
 550
 551         mutex_lock(&root->fs_info->fs_mutex);
 552         trans = btrfs_start_transaction(root, 1);
 553         if (IS_ERR(trans)) {
 554                 err = PTR_ERR(trans);
 555                 goto out_unlock;
 556         }
 557         inode = btrfs_new_inode(trans, dir, S_IFDIR | mode);
 558         if (IS_ERR(inode)) {
 559                 err = PTR_ERR(inode);
 560                 goto out_fail;
 561         }
 562         drop_on_err = 1;
 563         inode->i_op = &btrfs_dir_inode_operations;
 564         inode->i_fop = &btrfs_dir_file_operations;
 565
 566         err = btrfs_make_empty_dir(trans, inode, dir);
 567         if (err)
 568                 goto out_fail;
 569         err = btrfs_add_link(trans, dentry, inode);
 570         if (err)
 571                 goto out_fail;
 572         d_instantiate(dentry, inode);
 573         drop_on_err = 0;
 574
 575 out_fail:
 576         btrfs_end_transaction(trans, root);
 577 out_unlock:
 578         mutex_unlock(&root->fs_info->fs_mutex);
 579         if (drop_on_err)
 580                 iput(inode);
 581         return err;
 582 }
 583
 584 static int btrfs_sync_fs(struct super_block *sb, int wait)
 585 {
 586         struct btrfs_trans_handle *trans;
 587         struct btrfs_root *root;
 588         int ret;
 589
 590         sb->s_dirt = 0;
 591         if (!wait) {
 592                 filemap_flush(sb->s_bdev->bd_inode->i_mapping);
 593                 return 0;
 594         }
 595         filemap_write_and_wait(sb->s_bdev->bd_inode->i_mapping);
 596
 597         root = btrfs_sb(sb);
 598         mutex_lock(&root->fs_info->fs_mutex);
 599         trans = btrfs_start_transaction(root, 1);
 600         ret = btrfs_commit_transaction(trans, root);
 601         sb->s_dirt = 0;
 602         BUG_ON(ret);
 603 printk("btrfs sync_fs\n");
 604         mutex_unlock(&root->fs_info->fs_mutex);
 605         return 0;
 606 }
 607
 608 static int btrfs_get_block(struct inode *inode, sector_t iblock,
 609                            struct buffer_head *result, int create)
 610 {
 611         int ret;
 612         int err = 0;
 613         u64 blocknr;
 614         u64 extent_start = 0;
 615         u64 extent_end = 0;
 616         u64 objectid = inode->i_ino;
 617         struct btrfs_path path;
 618         struct btrfs_root *root = btrfs_sb(inode->i_sb);
 619         struct btrfs_trans_handle *trans = NULL;
 620         struct btrfs_file_extent_item *item;
 621         struct btrfs_leaf *leaf;
 622         struct btrfs_disk_key *found_key;
 623
 624         btrfs_init_path(&path);
 625         mutex_lock(&root->fs_info->fs_mutex);
 626         if (create)
 627                 trans = btrfs_start_transaction(root, 1);
 628
 629
 630         ret = btrfs_lookup_file_extent(trans, root, &path,
 631                                        inode->i_ino, iblock, 1, 0);
 632         if (ret < 0) {
 633                 btrfs_release_path(root, &path);
 634                 err = ret;
 635                 goto out;
 636         }
 637
 638         if (ret != 0) {
 639                 if (path.slots[0] == 0) {
 640                         btrfs_release_path(root, &path);
 641                         goto allocate;
 642                 }
 643                 path.slots[0]--;
 644         }
 645
 646         item = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
 647                               struct btrfs_file_extent_item);
 648         leaf = btrfs_buffer_leaf(path.nodes[0]);
 649         blocknr = btrfs_file_extent_disk_blocknr(item);
 650         blocknr += btrfs_file_extent_offset(item);
 651
 652         /* exact match found, use it */
 653         if (ret == 0) {
 654                 err = 0;
 655                 map_bh(result, inode->i_sb, blocknr);
 656                 btrfs_release_path(root, &path);
 657                 goto out;
 658         }
 659
 660         /* are we inside the extent that was found? */
 661         found_key = &leaf->items[path.slots[0]].key;
 662         if (btrfs_disk_key_objectid(found_key) != objectid ||
 663             btrfs_disk_key_type(found_key) != BTRFS_EXTENT_DATA_KEY) {
 664                 extent_end = 0;
 665                 extent_start = 0;
 666                 btrfs_release_path(root, &path);
 667                 goto allocate;
 668         }
 669
 670         extent_start = btrfs_disk_key_offset(&leaf->items[path.slots[0]].key);
 671         extent_start += btrfs_file_extent_offset(item);
 672         extent_end = extent_start + btrfs_file_extent_num_blocks(item);
 673         btrfs_release_path(root, &path);
 674         if (iblock >= extent_start && iblock < extent_end) {
 675                 err = 0;
 676                 map_bh(result, inode->i_sb, blocknr + iblock - extent_start);
 677                 goto out;
 678         }
 679 allocate:
 680         /* ok, create a new extent */
 681         if (!create) {
 682                 err = 0;
 683                 goto out;
 684         }
 685         ret = btrfs_alloc_file_extent(trans, root, objectid, iblock,
 686                                       1, extent_end, &blocknr);
 687         if (ret) {
 688                 err = ret;
 689                 goto out;
 690         }
 691         map_bh(result, inode->i_sb, blocknr);
 692
 693 out:
 694         if (trans)
 695                 btrfs_end_transaction(trans, root);
 696         mutex_unlock(&root->fs_info->fs_mutex);
 697         return err;
 698 }
 699
 700 static int btrfs_prepare_write(struct file *file, struct page *page,
 701                                unsigned from, unsigned to)
 702 {
 703         return nobh_prepare_write(page, from, to, btrfs_get_block);
 704 }
 705
 706 static void btrfs_write_super(struct super_block *sb)
 707 {
 708         btrfs_sync_fs(sb, 1);
 709 }
 710
 711 static int btrfs_readpage(struct file *file, struct page *page)
 712 {
 713         return mpage_readpage(page, btrfs_get_block);
 714 }
 715
 716 static int btrfs_readpages(struct file *file, struct address_space *mapping,
 717                            struct list_head *pages, unsigned nr_pages)
 718 {
 719         return mpage_readpages(mapping, pages, nr_pages, btrfs_get_block);
 720 }
 721
 722 static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
 723 {
 724         return nobh_writepage(page, btrfs_get_block, wbc);
 725 }
 726
 727 static int btrfs_get_sb(struct file_system_type *fs_type,
 728         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 729 {
 730         return get_sb_bdev(fs_type, flags, dev_name, data,
 731                            btrfs_fill_super, mnt);
 732 }
 733
 734 static struct file_system_type btrfs_fs_type = {
 735         .owner          = THIS_MODULE,
 736         .name           = "btrfs",
 737         .get_sb         = btrfs_get_sb,
 738         .kill_sb        = kill_block_super,
 739         .fs_flags       = FS_REQUIRES_DEV,
 740 };
 741
 742 static struct super_operations btrfs_super_ops = {
 743         .statfs         = simple_statfs,
 744         .delete_inode   = btrfs_delete_inode,
 745         .put_super      = btrfs_put_super,
 746         .read_inode     = btrfs_read_locked_inode,
 747         .write_super    = btrfs_write_super,
 748         .sync_fs        = btrfs_sync_fs,
 749         .write_inode    = btrfs_write_inode,
 750 };
 751
 752 static struct inode_operations btrfs_dir_inode_operations = {
 753         .lookup         = btrfs_lookup,
 754         .create         = btrfs_create,
 755         .unlink         = btrfs_unlink,
 756         .mkdir          = btrfs_mkdir,
 757 };
 758
 759 static struct file_operations btrfs_dir_file_operations = {
 760         .llseek         = generic_file_llseek,
 761         .read           = generic_read_dir,
 762         .readdir        = btrfs_readdir,
 763 };
 764
 765 static struct address_space_operations btrfs_aops = {
 766         .readpage       = btrfs_readpage,
 767         .readpages      = btrfs_readpages,
 768         .writepage      = btrfs_writepage,
 769         .sync_page      = block_sync_page,
 770         .prepare_write  = btrfs_prepare_write,
 771         .commit_write   = nobh_commit_write,
 772 };
 773
 774 static struct inode_operations btrfs_file_inode_operations = {
 775         .truncate       = NULL,
 776 };
 777
 778 static struct file_operations btrfs_file_operations = {
 779         .llseek         = generic_file_llseek,
 780         .read           = do_sync_read,
 781         .write          = do_sync_write,
 782         .aio_read       = generic_file_aio_read,
 783         .aio_write      = generic_file_aio_write,
 784         .mmap           = generic_file_mmap,
 785         .open           = generic_file_open,
 786         .sendfile       = generic_file_sendfile,
 787         .splice_read    = generic_file_splice_read,
 788         .splice_write   = generic_file_splice_write,
 789 };
 790
 791 static int __init init_btrfs_fs(void)
 792 {
 793         printk("btrfs loaded!\n");
 794         return register_filesystem(&btrfs_fs_type);
 795 }
 796
 797 static void __exit exit_btrfs_fs(void)
 798 {
 799         unregister_filesystem(&btrfs_fs_type);
 800         printk("btrfs unloaded\n");
 801 }
 802
 803 module_init(init_btrfs_fs)
 804 module_exit(exit_btrfs_fs)
 805
 806 MODULE_LICENSE("GPL");