fs/btrfs/disk-io.c

   1 #include <linux/module.h>
   2 #include <linux/fs.h>
   3 #include <linux/blkdev.h>
   4 #include <linux/crypto.h>
   5 #include <linux/scatterlist.h>
   6 #include <linux/swap.h>
   7 #include "ctree.h"
   8 #include "disk-io.h"
   9 #include "transaction.h"
  10
  11
  12 static int check_tree_block(struct btrfs_root *root, struct buffer_head *buf)
  13 {
  14         struct btrfs_node *node = btrfs_buffer_node(buf);
  15         if (buf->b_blocknr != btrfs_header_blocknr(&node->header)) {
  16                 BUG();
  17         }
  18         if (root->node && btrfs_header_parentid(&node->header) !=
  19             btrfs_header_parentid(btrfs_buffer_header(root->node))) {
  20                 BUG();
  21         }
  22         return 0;
  23 }
  24
  25 struct buffer_head *btrfs_find_tree_block(struct btrfs_root *root, u64 blocknr)
  26 {
  27         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
  28         int blockbits = root->fs_info->sb->s_blocksize_bits;
  29         unsigned long index = blocknr >> (PAGE_CACHE_SHIFT - blockbits);
  30         struct page *page;
  31         struct buffer_head *bh;
  32         struct buffer_head *head;
  33         struct buffer_head *ret = NULL;
  34
  35         page = find_lock_page(mapping, index);
  36         if (!page)
  37                 return NULL;
  38
  39         if (!page_has_buffers(page))
  40                 goto out_unlock;
  41
  42         head = page_buffers(page);
  43         bh = head;
  44         do {
  45                 if (buffer_mapped(bh) && bh->b_blocknr == blocknr) {
  46                         ret = bh;
  47                         get_bh(bh);
  48                         goto out_unlock;
  49                 }
  50                 bh = bh->b_this_page;
  51         } while (bh != head);
  52 out_unlock:
  53         unlock_page(page);
  54         if (ret)
  55                 touch_buffer(ret);
  56         page_cache_release(page);
  57         return ret;
  58 }
  59
  60 struct buffer_head *btrfs_find_create_tree_block(struct btrfs_root *root,
  61                                                  u64 blocknr)
  62 {
  63         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
  64         int blockbits = root->fs_info->sb->s_blocksize_bits;
  65         unsigned long index = blocknr >> (PAGE_CACHE_SHIFT - blockbits);
  66         struct page *page;
  67         struct buffer_head *bh;
  68         struct buffer_head *head;
  69         struct buffer_head *ret = NULL;
  70         u64 first_block = index << (PAGE_CACHE_SHIFT - blockbits);
  71
  72         page = grab_cache_page(mapping, index);
  73         if (!page)
  74                 return NULL;
  75
  76         if (!page_has_buffers(page))
  77                 create_empty_buffers(page, root->fs_info->sb->s_blocksize, 0);
  78         head = page_buffers(page);
  79         bh = head;
  80         do {
  81                 if (!buffer_mapped(bh)) {
  82                         bh->b_bdev = root->fs_info->sb->s_bdev;
  83                         bh->b_blocknr = first_block;
  84                         set_buffer_mapped(bh);
  85                 }
  86                 if (bh->b_blocknr == blocknr) {
  87                         ret = bh;
  88                         get_bh(bh);
  89                         goto out_unlock;
  90                 }
  91                 bh = bh->b_this_page;
  92                 first_block++;
  93         } while (bh != head);
  94 out_unlock:
  95         unlock_page(page);
  96         if (ret)
  97                 touch_buffer(ret);
  98         page_cache_release(page);
  99         return ret;
 100 }
 101
 102 static sector_t max_block(struct block_device *bdev)
 103 {
 104         sector_t retval = ~((sector_t)0);
 105         loff_t sz = i_size_read(bdev->bd_inode);
 106
 107         if (sz) {
 108                 unsigned int size = block_size(bdev);
 109                 unsigned int sizebits = blksize_bits(size);
 110                 retval = (sz >> sizebits);
 111         }
 112         return retval;
 113 }
 114
 115 static int btree_get_block(struct inode *inode, sector_t iblock,
 116                            struct buffer_head *bh, int create)
 117 {
 118         if (iblock >= max_block(inode->i_sb->s_bdev)) {
 119                 if (create)
 120                         return -EIO;
 121
 122                 /*
 123                  * for reads, we're just trying to fill a partial page.
 124                  * return a hole, they will have to call get_block again
 125                  * before they can fill it, and they will get -EIO at that
 126                  * time
 127                  */
 128                 return 0;
 129         }
 130         bh->b_bdev = inode->i_sb->s_bdev;
 131         bh->b_blocknr = iblock;
 132         set_buffer_mapped(bh);
 133         return 0;
 134 }
 135
 136 int btrfs_csum_data(struct btrfs_root * root, char *data, size_t len,
 137                     char *result)
 138 {
 139         struct scatterlist sg;
 140         struct crypto_hash *tfm = root->fs_info->hash_tfm;
 141         struct hash_desc desc;
 142         int ret;
 143
 144         desc.tfm = tfm;
 145         desc.flags = 0;
 146         sg_init_one(&sg, data, len);
 147         spin_lock(&root->fs_info->hash_lock);
 148         ret = crypto_hash_digest(&desc, &sg, 1, result);
 149         spin_unlock(&root->fs_info->hash_lock);
 150         if (ret) {
 151                 printk("sha256 digest failed\n");
 152         }
 153         return ret;
 154 }
 155 static int csum_tree_block(struct btrfs_root *root, struct buffer_head *bh,
 156                            int verify)
 157 {
 158         char result[BTRFS_CSUM_SIZE];
 159         int ret;
 160         struct btrfs_node *node;
 161
 162         return 0;
 163         ret = btrfs_csum_data(root, bh->b_data + BTRFS_CSUM_SIZE,
 164                               bh->b_size - BTRFS_CSUM_SIZE, result);
 165         if (ret)
 166                 return ret;
 167         if (verify) {
 168                 if (memcmp(bh->b_data, result, BTRFS_CSUM_SIZE)) {
 169                         printk("checksum verify failed on %lu\n",
 170                                bh->b_blocknr);
 171                         return 1;
 172                 }
 173         } else {
 174                 node = btrfs_buffer_node(bh);
 175                 memcpy(node->header.csum, result, BTRFS_CSUM_SIZE);
 176         }
 177         return 0;
 178 }
 179
 180 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 181 {
 182 #if 0
 183         struct buffer_head *bh;
 184         struct btrfs_root *root = btrfs_sb(page->mapping->host->i_sb);
 185         struct buffer_head *head;
 186         if (!page_has_buffers(page)) {
 187                 create_empty_buffers(page, root->fs_info->sb->s_blocksize,
 188                                         (1 << BH_Dirty)|(1 << BH_Uptodate));
 189         }
 190         head = page_buffers(page);
 191         bh = head;
 192         do {
 193                 if (buffer_dirty(bh))
 194                         csum_tree_block(root, bh, 0);
 195                 bh = bh->b_this_page;
 196         } while (bh != head);
 197 #endif
 198         return block_write_full_page(page, btree_get_block, wbc);
 199 }
 200
 201 static int btree_readpage(struct file * file, struct page * page)
 202 {
 203         return block_read_full_page(page, btree_get_block);
 204 }
 205
 206 static struct address_space_operations btree_aops = {
 207         .readpage       = btree_readpage,
 208         .writepage      = btree_writepage,
 209         .sync_page      = block_sync_page,
 210 };
 211
 212 struct buffer_head *read_tree_block(struct btrfs_root *root, u64 blocknr)
 213 {
 214         struct buffer_head *bh = NULL;
 215
 216         bh = btrfs_find_create_tree_block(root, blocknr);
 217         if (!bh)
 218                 return bh;
 219         lock_buffer(bh);
 220         if (!buffer_uptodate(bh)) {
 221                 get_bh(bh);
 222                 bh->b_end_io = end_buffer_read_sync;
 223                 submit_bh(READ, bh);
 224                 wait_on_buffer(bh);
 225                 if (!buffer_uptodate(bh))
 226                         goto fail;
 227                 csum_tree_block(root, bh, 1);
 228         } else {
 229                 unlock_buffer(bh);
 230         }
 231         if (check_tree_block(root, bh))
 232                 BUG();
 233         return bh;
 234 fail:
 235         brelse(bh);
 236         return NULL;
 237
 238 }
 239
 240 int dirty_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 241                      struct buffer_head *buf)
 242 {
 243         mark_buffer_dirty(buf);
 244         return 0;
 245 }
 246
 247 int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 248                      struct buffer_head *buf)
 249 {
 250         clear_buffer_dirty(buf);
 251         return 0;
 252 }
 253
 254 static int __setup_root(struct btrfs_super_block *super,
 255                         struct btrfs_root *root,
 256                         struct btrfs_fs_info *fs_info,
 257                         u64 objectid)
 258 {
 259         root->node = NULL;
 260         root->commit_root = NULL;
 261         root->blocksize = btrfs_super_blocksize(super);
 262         root->ref_cows = 0;
 263         root->fs_info = fs_info;
 264         memset(&root->root_key, 0, sizeof(root->root_key));
 265         memset(&root->root_item, 0, sizeof(root->root_item));
 266         return 0;
 267 }
 268
 269 static int find_and_setup_root(struct btrfs_super_block *super,
 270                                struct btrfs_root *tree_root,
 271                                struct btrfs_fs_info *fs_info,
 272                                u64 objectid,
 273                                struct btrfs_root *root)
 274 {
 275         int ret;
 276
 277         __setup_root(super, root, fs_info, objectid);
 278         ret = btrfs_find_last_root(tree_root, objectid,
 279                                    &root->root_item, &root->root_key);
 280         BUG_ON(ret);
 281
 282         root->node = read_tree_block(root,
 283                                      btrfs_root_blocknr(&root->root_item));
 284         BUG_ON(!root->node);
 285         return 0;
 286 }
 287
 288 struct btrfs_root *open_ctree(struct super_block *sb,
 289                               struct buffer_head *sb_buffer,
 290                               struct btrfs_super_block *disk_super)
 291 {
 292         struct btrfs_root *root = kmalloc(sizeof(struct btrfs_root),
 293                                           GFP_NOFS);
 294         struct btrfs_root *extent_root = kmalloc(sizeof(struct btrfs_root),
 295                                                  GFP_NOFS);
 296         struct btrfs_root *tree_root = kmalloc(sizeof(struct btrfs_root),
 297                                                GFP_NOFS);
 298         struct btrfs_root *inode_root = kmalloc(sizeof(struct btrfs_root),
 299                                                 GFP_NOFS);
 300         struct btrfs_fs_info *fs_info = kmalloc(sizeof(*fs_info),
 301                                                 GFP_NOFS);
 302         int ret;
 303
 304         if (!btrfs_super_root(disk_super)) {
 305                 return NULL;
 306         }
 307         init_bit_radix(&fs_info->pinned_radix);
 308         init_bit_radix(&fs_info->pending_del_radix);
 309         sb_set_blocksize(sb, sb_buffer->b_size);
 310         fs_info->running_transaction = NULL;
 311         fs_info->fs_root = root;
 312         fs_info->tree_root = tree_root;
 313         fs_info->extent_root = extent_root;
 314         fs_info->inode_root = inode_root;
 315         fs_info->last_inode_alloc = 0;
 316         fs_info->last_inode_alloc_dirid = 0;
 317         fs_info->disk_super = disk_super;
 318         fs_info->sb = sb;
 319         fs_info->btree_inode = new_inode(sb);
 320         fs_info->btree_inode->i_ino = 1;
 321         fs_info->btree_inode->i_size = sb->s_bdev->bd_inode->i_size;
 322         fs_info->btree_inode->i_mapping->a_ops = &btree_aops;
 323         insert_inode_hash(fs_info->btree_inode);
 324
 325         mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS);
 326         fs_info->hash_tfm = crypto_alloc_hash("sha256", 0, CRYPTO_ALG_ASYNC);
 327         spin_lock_init(&fs_info->hash_lock);
 328
 329         if (!fs_info->hash_tfm || IS_ERR(fs_info->hash_tfm)) {
 330                 printk("failed to allocate sha256 hash\n");
 331                 return NULL;
 332         }
 333
 334         mutex_init(&fs_info->trans_mutex);
 335         mutex_init(&fs_info->fs_mutex);
 336         memset(&fs_info->current_insert, 0, sizeof(fs_info->current_insert));
 337         memset(&fs_info->last_insert, 0, sizeof(fs_info->last_insert));
 338
 339         __setup_root(disk_super, tree_root, fs_info, BTRFS_ROOT_TREE_OBJECTID);
 340
 341         fs_info->sb_buffer = read_tree_block(tree_root, sb_buffer->b_blocknr);
 342
 343         if (!fs_info->sb_buffer) {
 344 printk("failed2\n");
 345                 return NULL;
 346         }
 347         brelse(sb_buffer);
 348         sb_buffer = NULL;
 349         disk_super = (struct btrfs_super_block *)fs_info->sb_buffer->b_data;
 350         fs_info->disk_super = disk_super;
 351
 352         tree_root->node = read_tree_block(tree_root,
 353                                           btrfs_super_root(disk_super));
 354         BUG_ON(!tree_root->node);
 355
 356         ret = find_and_setup_root(disk_super, tree_root, fs_info,
 357                                   BTRFS_EXTENT_TREE_OBJECTID, extent_root);
 358         BUG_ON(ret);
 359
 360         ret = find_and_setup_root(disk_super, tree_root, fs_info,
 361                                   BTRFS_INODE_MAP_OBJECTID, inode_root);
 362         BUG_ON(ret);
 363
 364         ret = find_and_setup_root(disk_super, tree_root, fs_info,
 365                                   BTRFS_FS_TREE_OBJECTID, root);
 366         BUG_ON(ret);
 367         root->commit_root = root->node;
 368         get_bh(root->node);
 369         root->ref_cows = 1;
 370         root->fs_info->generation = root->root_key.offset + 1;
 371         return root;
 372 }
 373
 374 int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root
 375                       *root)
 376 {
 377         struct buffer_head *bh = root->fs_info->sb_buffer;
 378         btrfs_set_super_root(root->fs_info->disk_super,
 379                              root->fs_info->tree_root->node->b_blocknr);
 380         lock_buffer(bh);
 381         clear_buffer_dirty(bh);
 382         csum_tree_block(root, bh, 0);
 383         bh->b_end_io = end_buffer_write_sync;
 384         get_bh(bh);
 385         submit_bh(WRITE, bh);
 386         wait_on_buffer(bh);
 387         if (!buffer_uptodate(bh)) {
 388                 WARN_ON(1);
 389                 return -EIO;
 390         }
 391         return 0;
 392 }
 393
 394 int close_ctree(struct btrfs_root *root)
 395 {
 396         int ret;
 397         struct btrfs_trans_handle *trans;
 398
 399         trans = btrfs_start_transaction(root, 1);
 400         btrfs_commit_transaction(trans, root);
 401         /* run commit again to  drop the original snapshot */
 402         trans = btrfs_start_transaction(root, 1);
 403         btrfs_commit_transaction(trans, root);
 404         ret = btrfs_write_and_wait_transaction(NULL, root);
 405         BUG_ON(ret);
 406         write_ctree_super(NULL, root);
 407
 408         if (root->node)
 409                 btrfs_block_release(root, root->node);
 410         if (root->fs_info->extent_root->node)
 411                 btrfs_block_release(root->fs_info->extent_root,
 412                                     root->fs_info->extent_root->node);
 413         if (root->fs_info->inode_root->node)
 414                 btrfs_block_release(root->fs_info->inode_root,
 415                                     root->fs_info->inode_root->node);
 416         if (root->fs_info->tree_root->node)
 417                 btrfs_block_release(root->fs_info->tree_root,
 418                                     root->fs_info->tree_root->node);
 419         btrfs_block_release(root, root->commit_root);
 420         btrfs_block_release(root, root->fs_info->sb_buffer);
 421         crypto_free_hash(root->fs_info->hash_tfm);
 422         truncate_inode_pages(root->fs_info->btree_inode->i_mapping, 0);
 423         iput(root->fs_info->btree_inode);
 424         kfree(root->fs_info->extent_root);
 425         kfree(root->fs_info->inode_root);
 426         kfree(root->fs_info->tree_root);
 427         kfree(root->fs_info);
 428         kfree(root);
 429         return 0;
 430 }
 431
 432 void btrfs_block_release(struct btrfs_root *root, struct buffer_head *buf)
 433 {
 434         brelse(buf);
 435 }
 436