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;
 137                 int frag_size;
 138                 u64 frag_blk;
 139                 struct squashfs_reg_inode *sqsh_ino = &squashfs_ino.reg;
 140
 141                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 142                                                         sizeof(*sqsh_ino));
 143                 if (err < 0)
 144                         goto failed_read;
 145
 146                 frag = le32_to_cpu(sqsh_ino->fragment);
 147                 if (frag != SQUASHFS_INVALID_FRAG) {
 148                         frag_offset = le32_to_cpu(sqsh_ino->offset);
 149                         frag_size = squashfs_frag_lookup(sb, frag, &frag_blk);
 150                         if (frag_size < 0) {
 151                                 err = frag_size;
 152                                 goto failed_read;
 153                         }
 154                 } else {
 155                         frag_blk = SQUASHFS_INVALID_BLK;
 156                         frag_size = 0;
 157                         frag_offset = 0;
 158                 }
 159
 160                 inode->i_nlink = 1;
 161                 inode->i_size = le32_to_cpu(sqsh_ino->file_size);
 162                 inode->i_fop = &generic_ro_fops;
 163                 inode->i_mode |= S_IFREG;
 164                 inode->i_blocks = ((inode->i_size - 1) >> 9) + 1;
 165                 squashfs_i(inode)->fragment_block = frag_blk;
 166                 squashfs_i(inode)->fragment_size = frag_size;
 167                 squashfs_i(inode)->fragment_offset = frag_offset;
 168                 squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
 169                 squashfs_i(inode)->block_list_start = block;
 170                 squashfs_i(inode)->offset = offset;
 171                 inode->i_data.a_ops = &squashfs_aops;
 172
 173                 TRACE("File inode %x:%x, start_block %llx, block_list_start "
 174                         "%llx, offset %x\n", SQUASHFS_INODE_BLK(ino),
 175                         offset, squashfs_i(inode)->start, block, offset);
 176                 break;
 177         }
 178         case SQUASHFS_LREG_TYPE: {
 179                 unsigned int frag_offset, frag;
 180                 int frag_size;
 181                 u64 frag_blk;
 182                 struct squashfs_lreg_inode *sqsh_ino = &squashfs_ino.lreg;
 183
 184                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 185                                                         sizeof(*sqsh_ino));
 186                 if (err < 0)
 187                         goto failed_read;
 188
 189                 frag = le32_to_cpu(sqsh_ino->fragment);
 190                 if (frag != SQUASHFS_INVALID_FRAG) {
 191                         frag_offset = le32_to_cpu(sqsh_ino->offset);
 192                         frag_size = squashfs_frag_lookup(sb, frag, &frag_blk);
 193                         if (frag_size < 0) {
 194                                 err = frag_size;
 195                                 goto failed_read;
 196                         }
 197                 } else {
 198                         frag_blk = SQUASHFS_INVALID_BLK;
 199                         frag_size = 0;
 200                         frag_offset = 0;
 201                 }
 202
 203                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 204                 inode->i_size = le64_to_cpu(sqsh_ino->file_size);
 205                 inode->i_fop = &generic_ro_fops;
 206                 inode->i_mode |= S_IFREG;
 207                 inode->i_blocks = ((inode->i_size -
 208                                 le64_to_cpu(sqsh_ino->sparse) - 1) >> 9) + 1;
 209
 210                 squashfs_i(inode)->fragment_block = frag_blk;
 211                 squashfs_i(inode)->fragment_size = frag_size;
 212                 squashfs_i(inode)->fragment_offset = frag_offset;
 213                 squashfs_i(inode)->start = le64_to_cpu(sqsh_ino->start_block);
 214                 squashfs_i(inode)->block_list_start = block;
 215                 squashfs_i(inode)->offset = offset;
 216                 inode->i_data.a_ops = &squashfs_aops;
 217
 218                 TRACE("File inode %x:%x, start_block %llx, block_list_start "
 219                         "%llx, offset %x\n", SQUASHFS_INODE_BLK(ino),
 220                         offset, squashfs_i(inode)->start, block, offset);
 221                 break;
 222         }
 223         case SQUASHFS_DIR_TYPE: {
 224                 struct squashfs_dir_inode *sqsh_ino = &squashfs_ino.dir;
 225
 226                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 227                                 sizeof(*sqsh_ino));
 228                 if (err < 0)
 229                         goto failed_read;
 230
 231                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 232                 inode->i_size = le16_to_cpu(sqsh_ino->file_size);
 233                 inode->i_op = &squashfs_dir_inode_ops;
 234                 inode->i_fop = &squashfs_dir_ops;
 235                 inode->i_mode |= S_IFDIR;
 236                 squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
 237                 squashfs_i(inode)->offset = le16_to_cpu(sqsh_ino->offset);
 238                 squashfs_i(inode)->dir_idx_cnt = 0;
 239                 squashfs_i(inode)->parent = le32_to_cpu(sqsh_ino->parent_inode);
 240
 241                 TRACE("Directory inode %x:%x, start_block %llx, offset %x\n",
 242                                 SQUASHFS_INODE_BLK(ino), offset,
 243                                 squashfs_i(inode)->start,
 244                                 le16_to_cpu(sqsh_ino->offset));
 245                 break;
 246         }
 247         case SQUASHFS_LDIR_TYPE: {
 248                 struct squashfs_ldir_inode *sqsh_ino = &squashfs_ino.ldir;
 249
 250                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 251                                 sizeof(*sqsh_ino));
 252                 if (err < 0)
 253                         goto failed_read;
 254
 255                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 256                 inode->i_size = le32_to_cpu(sqsh_ino->file_size);
 257                 inode->i_op = &squashfs_dir_inode_ops;
 258                 inode->i_fop = &squashfs_dir_ops;
 259                 inode->i_mode |= S_IFDIR;
 260                 squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
 261                 squashfs_i(inode)->offset = le16_to_cpu(sqsh_ino->offset);
 262                 squashfs_i(inode)->dir_idx_start = block;
 263                 squashfs_i(inode)->dir_idx_offset = offset;
 264                 squashfs_i(inode)->dir_idx_cnt = le16_to_cpu(sqsh_ino->i_count);
 265                 squashfs_i(inode)->parent = le32_to_cpu(sqsh_ino->parent_inode);
 266
 267                 TRACE("Long directory inode %x:%x, start_block %llx, offset "
 268                                 "%x\n", SQUASHFS_INODE_BLK(ino), offset,
 269                                 squashfs_i(inode)->start,
 270                                 le16_to_cpu(sqsh_ino->offset));
 271                 break;
 272         }
 273         case SQUASHFS_SYMLINK_TYPE:
 274         case SQUASHFS_LSYMLINK_TYPE: {
 275                 struct squashfs_symlink_inode *sqsh_ino = &squashfs_ino.symlink;
 276
 277                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 278                                 sizeof(*sqsh_ino));
 279                 if (err < 0)
 280                         goto failed_read;
 281
 282                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 283                 inode->i_size = le32_to_cpu(sqsh_ino->symlink_size);
 284                 inode->i_op = &page_symlink_inode_operations;
 285                 inode->i_data.a_ops = &squashfs_symlink_aops;
 286                 inode->i_mode |= S_IFLNK;
 287                 squashfs_i(inode)->start = block;
 288                 squashfs_i(inode)->offset = offset;
 289
 290                 TRACE("Symbolic link inode %x:%x, start_block %llx, offset "
 291                                 "%x\n", SQUASHFS_INODE_BLK(ino), offset,
 292                                 block, offset);
 293                 break;
 294         }
 295         case SQUASHFS_BLKDEV_TYPE:
 296         case SQUASHFS_CHRDEV_TYPE:
 297         case SQUASHFS_LBLKDEV_TYPE:
 298         case SQUASHFS_LCHRDEV_TYPE: {
 299                 struct squashfs_dev_inode *sqsh_ino = &squashfs_ino.dev;
 300                 unsigned int rdev;
 301
 302                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 303                                 sizeof(*sqsh_ino));
 304                 if (err < 0)
 305                         goto failed_read;
 306
 307                 if (type == SQUASHFS_CHRDEV_TYPE)
 308                         inode->i_mode |= S_IFCHR;
 309                 else
 310                         inode->i_mode |= S_IFBLK;
 311                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 312                 rdev = le32_to_cpu(sqsh_ino->rdev);
 313                 init_special_inode(inode, inode->i_mode, new_decode_dev(rdev));
 314
 315                 TRACE("Device inode %x:%x, rdev %x\n",
 316                                 SQUASHFS_INODE_BLK(ino), offset, rdev);
 317                 break;
 318         }
 319         case SQUASHFS_FIFO_TYPE:
 320         case SQUASHFS_SOCKET_TYPE:
 321         case SQUASHFS_LFIFO_TYPE:
 322         case SQUASHFS_LSOCKET_TYPE: {
 323                 struct squashfs_ipc_inode *sqsh_ino = &squashfs_ino.ipc;
 324
 325                 err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
 326                                 sizeof(*sqsh_ino));
 327                 if (err < 0)
 328                         goto failed_read;
 329
 330                 if (type == SQUASHFS_FIFO_TYPE)
 331                         inode->i_mode |= S_IFIFO;
 332                 else
 333                         inode->i_mode |= S_IFSOCK;
 334                 inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 335                 init_special_inode(inode, inode->i_mode, 0);
 336                 break;
 337         }
 338         default:
 339                 ERROR("Unknown inode type %d in squashfs_iget!\n", type);
 340                 return -EINVAL;
 341         }
 342
 343         return 0;
 344
 345 failed_read:
 346         ERROR("Unable to read inode 0x%llx\n", ino);
 347         return err;
 348 }