git.oblomov.eu Git - linux-2.6/blob - fs/squashfs/inode.c

   1 /*
   2  * Squashfs - a compressed read only filesystem for Linux
   3  *
   4  * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
   5  * Phillip Lougher <phillip@lougher.demon.co.uk>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version 2,
  10  * or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  20  *
  21  * inode.c
  22  */
  23
  24 /*
  25  * This file implements code to create and read inodes from disk.
  26  *
  27  * Inodes in Squashfs are identified by a 48-bit inode which encodes the
  28  * location of the compressed metadata block containing the inode, and the byte
  29  * offset into that block where the inode is placed (<block, offset>).
  30  *
  31  * To maximise compression there are different inodes for each file type
  32  * (regular file, directory, device, etc.), the inode contents and length
  33  * varying with the type.
  34  *
  35  * To further maximise compression, two types of regular file inode and
  36  * directory inode are defined: inodes optimised for frequently occurring
  37  * regular files and directories, and extended types where extra
  38  * information has to be stored.
  39  */
  40
  41 #include <linux/fs.h>
  42 #include <linux/vfs.h>
  43 #include <linux/zlib.h>
  44
  45 #include "squashfs_fs.h"
  46 #include "squashfs_fs_sb.h"
  47 #include "squashfs_fs_i.h"
  48 #include "squashfs.h"
  49
  50 /*
  51  * Initialise VFS inode with the base inode information common to all
  52  * Squashfs inode types.  Sqsh_ino contains the unswapped base inode
  53  * off disk.
  54  */
  55 static int squashfs_new_inode(struct super_block *sb, struct inode *inode,
  56                                 struct squashfs_base_inode *sqsh_ino)
  57 {
  58         int err;
  59
  60         err = squashfs_get_id(sb, le16_to_cpu(sqsh_ino->uid), &inode->i_uid);
  61         if (err)
  62                 return err;
  63
  64         err = squashfs_get_id(sb, le16_to_cpu(sqsh_ino->guid), &inode->i_gid);
  65         if (err)
  66                 return err;
  67
  68         inode->i_ino = le32_to_cpu(sqsh_ino->inode_number);
  69         inode->i_mtime.tv_sec = le32_to_cpu(sqsh_ino->mtime);
  70         inode->i_atime.tv_sec = inode->i_mtime.tv_sec;
  71         inode->i_ctime.tv_sec = inode->i_mtime.tv_sec;
  72         inode->i_mode = le16_to_cpu(sqsh_ino->mode);
  73         inode->i_size = 0;
  74
  75         return err;
  76 }
  77
  78
  79 struct inode *squashfs_iget(struct super_block *sb, long long ino,
  80                                 unsigned int ino_number)
  81 {
  82         struct inode *inode = iget_locked(sb, ino_number);
  83         int err;
  84
  85         TRACE("Entered squashfs_iget\n");
  86
  87         if (!inode)
  88                 return ERR_PTR(-ENOMEM);
  89         if (!(inode->i_state & I_NEW))
  90                 return inode;
  91
  92         err = squashfs_read_inode(inode, ino);
  93         if (err) {
  94                 iget_failed(inode);
  95                 return ERR_PTR(err);
  96         }
  97
  98         unlock_new_inode(inode);
  99         return inode;
 100 }
 101
 102
 103 /*
 104  * Initialise VFS inode by reading inode from inode table (compressed
 105  * metadata).  The format and amount of data read depends on type.
 106  */
 107 int squashfs_read_inode(struct inode *inode, long long ino)
 108 {
 109         struct super_block *sb = inode->i_sb;
 110         struct squashfs_sb_info *msblk = sb->s_fs_info;
 111         u64 block = SQUASHFS_INODE_BLK(ino) + msblk->inode_table;
 112         int err, type, offset = SQUASHFS_INODE_OFFSET(ino);
 113         union squashfs_inode squashfs_ino;
 114         struct squashfs_base_inode *sqshb_ino = &squashfs_ino.base;
 115
 116         TRACE("Entered squashfs_read_inode\n");
 117
 118         /*
 119          * Read inode base common to all inode types.
 120          */
 121         err = squashfs_read_metadata(sb, sqshb_ino, &block,
 122                                 &offset, sizeof(*sqshb_ino));
 123         if (err < 0)
 124                 goto failed_read;
 125
 126         err = squashfs_new_inode(sb, inode, sqshb_ino);
 127         if (err)
 128                 goto failed_read;
 129
 130         block = SQUASHFS_INODE_BLK(ino) + msblk->inode_table;
 131         offset = SQUASHFS_INODE_OFFSET(ino);
 132
 133         type = le16_to_cpu(sqshb_ino->inode_type);
 134         switch (type) {
 135         case SQUASHFS_REG_TYPE: {
 136                 unsigned int frag_offset, frag_size, frag;
 137                 u64 frag_blk;
 138                 struct squashfs_reg_inode *sqsh_ino = &squashfs_ino.reg;
 139
 140                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 141                                                         sizeof(*sqsh_ino));
 142                 if (err < 0)
 143                         goto failed_read;
 144
 145                 frag = le32_to_cpu(sqsh_ino->fragment);
 146                 if (frag != SQUASHFS_INVALID_FRAG) {
 147                         frag_offset = le32_to_cpu(sqsh_ino->offset);
 148                         frag_size = squashfs_frag_lookup(sb, frag, &frag_blk);
 149                         if (frag_size < 0) {
 150                                 err = frag_size;
 151                                 goto failed_read;
 152                         }
 153                 } else {
 154                         frag_blk = SQUASHFS_INVALID_BLK;
 155                         frag_size = 0;
 156                         frag_offset = 0;
 157                 }
 158
 159                 inode->i_nlink = 1;
 160                 inode->i_size = le32_to_cpu(sqsh_ino->file_size);
 161                 inode->i_fop = &generic_ro_fops;
 162                 inode->i_mode |= S_IFREG;
 163                 inode->i_blocks = ((inode->i_size - 1) >> 9) + 1;
 164                 squashfs_i(inode)->fragment_block = frag_blk;
 165                 squashfs_i(inode)->fragment_size = frag_size;
 166                 squashfs_i(inode)->fragment_offset = frag_offset;
 167                 squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
 168                 squashfs_i(inode)->block_list_start = block;
 169                 squashfs_i(inode)->offset = offset;
 170                 inode->i_data.a_ops = &squashfs_aops;
 171
 172                 TRACE("File inode %x:%x, start_block %llx, block_list_start "
 173                         "%llx, offset %x\n", SQUASHFS_INODE_BLK(ino),
 174                         offset, squashfs_i(inode)->start, block, offset);
 175                 break;
 176         }
 177         case SQUASHFS_LREG_TYPE: {
 178                 unsigned int frag_offset, frag_size, frag;
 179                 u64 frag_blk;
 180                 struct squashfs_lreg_inode *sqsh_ino = &squashfs_ino.lreg;
 181
 182                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 183                                                         sizeof(*sqsh_ino));
 184                 if (err < 0)
 185                         goto failed_read;
 186
 187                 frag = le32_to_cpu(sqsh_ino->fragment);
 188                 if (frag != SQUASHFS_INVALID_FRAG) {
 189                         frag_offset = le32_to_cpu(sqsh_ino->offset);
 190                         frag_size = squashfs_frag_lookup(sb, frag, &frag_blk);
 191                         if (frag_size < 0) {
 192                                 err = frag_size;
 193                                 goto failed_read;
 194                         }
 195                 } else {
 196                         frag_blk = SQUASHFS_INVALID_BLK;
 197                         frag_size = 0;
 198                         frag_offset = 0;
 199                 }
 200
 201                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 202                 inode->i_size = le64_to_cpu(sqsh_ino->file_size);
 203                 inode->i_fop = &generic_ro_fops;
 204                 inode->i_mode |= S_IFREG;
 205                 inode->i_blocks = ((inode->i_size -
 206                                 le64_to_cpu(sqsh_ino->sparse) - 1) >> 9) + 1;
 207
 208                 squashfs_i(inode)->fragment_block = frag_blk;
 209                 squashfs_i(inode)->fragment_size = frag_size;
 210                 squashfs_i(inode)->fragment_offset = frag_offset;
 211                 squashfs_i(inode)->start = le64_to_cpu(sqsh_ino->start_block);
 212                 squashfs_i(inode)->block_list_start = block;
 213                 squashfs_i(inode)->offset = offset;
 214                 inode->i_data.a_ops = &squashfs_aops;
 215
 216                 TRACE("File inode %x:%x, start_block %llx, block_list_start "
 217                         "%llx, offset %x\n", SQUASHFS_INODE_BLK(ino),
 218                         offset, squashfs_i(inode)->start, block, offset);
 219                 break;
 220         }
 221         case SQUASHFS_DIR_TYPE: {
 222                 struct squashfs_dir_inode *sqsh_ino = &squashfs_ino.dir;
 223
 224                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 225                                 sizeof(*sqsh_ino));
 226                 if (err < 0)
 227                         goto failed_read;
 228
 229                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 230                 inode->i_size = le16_to_cpu(sqsh_ino->file_size);
 231                 inode->i_op = &squashfs_dir_inode_ops;
 232                 inode->i_fop = &squashfs_dir_ops;
 233                 inode->i_mode |= S_IFDIR;
 234                 squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
 235                 squashfs_i(inode)->offset = le16_to_cpu(sqsh_ino->offset);
 236                 squashfs_i(inode)->dir_idx_cnt = 0;
 237                 squashfs_i(inode)->parent = le32_to_cpu(sqsh_ino->parent_inode);
 238
 239                 TRACE("Directory inode %x:%x, start_block %llx, offset %x\n",
 240                                 SQUASHFS_INODE_BLK(ino), offset,
 241                                 squashfs_i(inode)->start,
 242                                 le16_to_cpu(sqsh_ino->offset));
 243                 break;
 244         }
 245         case SQUASHFS_LDIR_TYPE: {
 246                 struct squashfs_ldir_inode *sqsh_ino = &squashfs_ino.ldir;
 247
 248                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 249                                 sizeof(*sqsh_ino));
 250                 if (err < 0)
 251                         goto failed_read;
 252
 253                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 254                 inode->i_size = le32_to_cpu(sqsh_ino->file_size);
 255                 inode->i_op = &squashfs_dir_inode_ops;
 256                 inode->i_fop = &squashfs_dir_ops;
 257                 inode->i_mode |= S_IFDIR;
 258                 squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
 259                 squashfs_i(inode)->offset = le16_to_cpu(sqsh_ino->offset);
 260                 squashfs_i(inode)->dir_idx_start = block;
 261                 squashfs_i(inode)->dir_idx_offset = offset;
 262                 squashfs_i(inode)->dir_idx_cnt = le16_to_cpu(sqsh_ino->i_count);
 263                 squashfs_i(inode)->parent = le32_to_cpu(sqsh_ino->parent_inode);
 264
 265                 TRACE("Long directory inode %x:%x, start_block %llx, offset "
 266                                 "%x\n", SQUASHFS_INODE_BLK(ino), offset,
 267                                 squashfs_i(inode)->start,
 268                                 le16_to_cpu(sqsh_ino->offset));
 269                 break;
 270         }
 271         case SQUASHFS_SYMLINK_TYPE:
 272         case SQUASHFS_LSYMLINK_TYPE: {
 273                 struct squashfs_symlink_inode *sqsh_ino = &squashfs_ino.symlink;
 274
 275                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 276                                 sizeof(*sqsh_ino));
 277                 if (err < 0)
 278                         goto failed_read;
 279
 280                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 281                 inode->i_size = le32_to_cpu(sqsh_ino->symlink_size);
 282                 inode->i_op = &page_symlink_inode_operations;
 283                 inode->i_data.a_ops = &squashfs_symlink_aops;
 284                 inode->i_mode |= S_IFLNK;
 285                 squashfs_i(inode)->start = block;
 286                 squashfs_i(inode)->offset = offset;
 287
 288                 TRACE("Symbolic link inode %x:%x, start_block %llx, offset "
 289                                 "%x\n", SQUASHFS_INODE_BLK(ino), offset,
 290                                 block, offset);
 291                 break;
 292         }
 293         case SQUASHFS_BLKDEV_TYPE:
 294         case SQUASHFS_CHRDEV_TYPE:
 295         case SQUASHFS_LBLKDEV_TYPE:
 296         case SQUASHFS_LCHRDEV_TYPE: {
 297                 struct squashfs_dev_inode *sqsh_ino = &squashfs_ino.dev;
 298                 unsigned int rdev;
 299
 300                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 301                                 sizeof(*sqsh_ino));
 302                 if (err < 0)
 303                         goto failed_read;
 304
 305                 if (type == SQUASHFS_CHRDEV_TYPE)
 306                         inode->i_mode |= S_IFCHR;
 307                 else
 308                         inode->i_mode |= S_IFBLK;
 309                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 310                 rdev = le32_to_cpu(sqsh_ino->rdev);
 311                 init_special_inode(inode, inode->i_mode, new_decode_dev(rdev));
 312
 313                 TRACE("Device inode %x:%x, rdev %x\n",
 314                                 SQUASHFS_INODE_BLK(ino), offset, rdev);
 315                 break;
 316         }
 317         case SQUASHFS_FIFO_TYPE:
 318         case SQUASHFS_SOCKET_TYPE:
 319         case SQUASHFS_LFIFO_TYPE:
 320         case SQUASHFS_LSOCKET_TYPE: {
 321                 struct squashfs_ipc_inode *sqsh_ino = &squashfs_ino.ipc;
 322
 323                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 324                                 sizeof(*sqsh_ino));
 325                 if (err < 0)
 326                         goto failed_read;
 327
 328                 if (type == SQUASHFS_FIFO_TYPE)
 329                         inode->i_mode |= S_IFIFO;
 330                 else
 331                         inode->i_mode |= S_IFSOCK;
 332                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 333                 init_special_inode(inode, inode->i_mode, 0);
 334                 break;
 335         }
 336         default:
 337                 ERROR("Unknown inode type %d in squashfs_iget!\n", type);
 338                 return -EINVAL;
 339         }
 340
 341         return 0;
 342
 343 failed_read:
 344         ERROR("Unable to read inode 0x%llx\n", ino);
 345         return err;
 346 }