Squashfs: inode operations

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>

diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c
new file mode 100644 (file)
index 0000000..7a63398
--- /dev/null
+++ b/fs/squashfs/inode.c
@@ -0,0 +1,346 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * inode.c
+ */
+
+/*
+ * This file implements code to create and read inodes from disk.
+ *
+ * Inodes in Squashfs are identified by a 48-bit inode which encodes the
+ * location of the compressed metadata block containing the inode, and the byte
+ * offset into that block where the inode is placed (<block, offset>).
+ *
+ * To maximise compression there are different inodes for each file type
+ * (regular file, directory, device, etc.), the inode contents and length
+ * varying with the type.
+ *
+ * To further maximise compression, two types of regular file inode and
+ * directory inode are defined: inodes optimised for frequently occurring
+ * regular files and directories, and extended types where extra
+ * information has to be stored.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/zlib.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+/*
+ * Initialise VFS inode with the base inode information common to all
+ * Squashfs inode types.  Sqsh_ino contains the unswapped base inode
+ * off disk.
+ */
+static int squashfs_new_inode(struct super_block *sb, struct inode *inode,
+                               struct squashfs_base_inode *sqsh_ino)
+{
+       int err;
+
+       err = squashfs_get_id(sb, le16_to_cpu(sqsh_ino->uid), &inode->i_uid);
+       if (err)
+               return err;
+
+       err = squashfs_get_id(sb, le16_to_cpu(sqsh_ino->guid), &inode->i_gid);
+       if (err)
+               return err;
+
+       inode->i_ino = le32_to_cpu(sqsh_ino->inode_number);
+       inode->i_mtime.tv_sec = le32_to_cpu(sqsh_ino->mtime);
+       inode->i_atime.tv_sec = inode->i_mtime.tv_sec;
+       inode->i_ctime.tv_sec = inode->i_mtime.tv_sec;
+       inode->i_mode = le16_to_cpu(sqsh_ino->mode);
+       inode->i_size = 0;
+
+       return err;
+}
+
+
+struct inode *squashfs_iget(struct super_block *sb, long long ino,
+                               unsigned int ino_number)
+{
+       struct inode *inode = iget_locked(sb, ino_number);
+       int err;
+
+       TRACE("Entered squashfs_iget\n");
+
+       if (!inode)
+               return ERR_PTR(-ENOMEM);
+       if (!(inode->i_state & I_NEW))
+               return inode;
+
+       err = squashfs_read_inode(inode, ino);
+       if (err) {
+               iget_failed(inode);
+               return ERR_PTR(err);
+       }
+
+       unlock_new_inode(inode);
+       return inode;
+}
+
+
+/*
+ * Initialise VFS inode by reading inode from inode table (compressed
+ * metadata).  The format and amount of data read depends on type.
+ */
+int squashfs_read_inode(struct inode *inode, long long ino)
+{
+       struct super_block *sb = inode->i_sb;
+       struct squashfs_sb_info *msblk = sb->s_fs_info;
+       u64 block = SQUASHFS_INODE_BLK(ino) + msblk->inode_table;
+       int err, type, offset = SQUASHFS_INODE_OFFSET(ino);
+       union squashfs_inode squashfs_ino;
+       struct squashfs_base_inode *sqshb_ino = &squashfs_ino.base;
+
+       TRACE("Entered squashfs_read_inode\n");
+
+       /*
+        * Read inode base common to all inode types.
+        */
+       err = squashfs_read_metadata(sb, sqshb_ino, &block,
+                               &offset, sizeof(*sqshb_ino));
+       if (err < 0)
+               goto failed_read;
+
+       err = squashfs_new_inode(sb, inode, sqshb_ino);
+       if (err)
+               goto failed_read;
+
+       block = SQUASHFS_INODE_BLK(ino) + msblk->inode_table;
+       offset = SQUASHFS_INODE_OFFSET(ino);
+
+       type = le16_to_cpu(sqshb_ino->inode_type);
+       switch (type) {
+       case SQUASHFS_REG_TYPE: {
+               unsigned int frag_offset, frag_size, frag;
+               u64 frag_blk;
+               struct squashfs_reg_inode *sqsh_ino = &squashfs_ino.reg;
+
+               err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
+                                                       sizeof(*sqsh_ino));
+               if (err < 0)
+                       goto failed_read;
+
+               frag = le32_to_cpu(sqsh_ino->fragment);
+               if (frag != SQUASHFS_INVALID_FRAG) {
+                       frag_offset = le32_to_cpu(sqsh_ino->offset);
+                       frag_size = squashfs_frag_lookup(sb, frag, &frag_blk);
+                       if (frag_size < 0) {
+                               err = frag_size;
+                               goto failed_read;
+                       }
+               } else {
+                       frag_blk = SQUASHFS_INVALID_BLK;
+                       frag_size = 0;
+                       frag_offset = 0;
+               }
+
+               inode->i_nlink = 1;
+               inode->i_size = le32_to_cpu(sqsh_ino->file_size);
+               inode->i_fop = &generic_ro_fops;
+               inode->i_mode |= S_IFREG;
+               inode->i_blocks = ((inode->i_size - 1) >> 9) + 1;
+               squashfs_i(inode)->fragment_block = frag_blk;
+               squashfs_i(inode)->fragment_size = frag_size;
+               squashfs_i(inode)->fragment_offset = frag_offset;
+               squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
+               squashfs_i(inode)->block_list_start = block;
+               squashfs_i(inode)->offset = offset;
+               inode->i_data.a_ops = &squashfs_aops;
+
+               TRACE("File inode %x:%x, start_block %llx, block_list_start "
+                       "%llx, offset %x\n", SQUASHFS_INODE_BLK(ino),
+                       offset, squashfs_i(inode)->start, block, offset);
+               break;
+       }
+       case SQUASHFS_LREG_TYPE: {
+               unsigned int frag_offset, frag_size, frag;
+               u64 frag_blk;
+               struct squashfs_lreg_inode *sqsh_ino = &squashfs_ino.lreg;
+
+               err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
+                                                       sizeof(*sqsh_ino));
+               if (err < 0)
+                       goto failed_read;
+
+               frag = le32_to_cpu(sqsh_ino->fragment);
+               if (frag != SQUASHFS_INVALID_FRAG) {
+                       frag_offset = le32_to_cpu(sqsh_ino->offset);
+                       frag_size = squashfs_frag_lookup(sb, frag, &frag_blk);
+                       if (frag_size < 0) {
+                               err = frag_size;
+                               goto failed_read;
+                       }
+               } else {
+                       frag_blk = SQUASHFS_INVALID_BLK;
+                       frag_size = 0;
+                       frag_offset = 0;
+               }
+
+               inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
+               inode->i_size = le64_to_cpu(sqsh_ino->file_size);
+               inode->i_fop = &generic_ro_fops;
+               inode->i_mode |= S_IFREG;
+               inode->i_blocks = ((inode->i_size -
+                               le64_to_cpu(sqsh_ino->sparse) - 1) >> 9) + 1;
+
+               squashfs_i(inode)->fragment_block = frag_blk;
+               squashfs_i(inode)->fragment_size = frag_size;
+               squashfs_i(inode)->fragment_offset = frag_offset;
+               squashfs_i(inode)->start = le64_to_cpu(sqsh_ino->start_block);
+               squashfs_i(inode)->block_list_start = block;
+               squashfs_i(inode)->offset = offset;
+               inode->i_data.a_ops = &squashfs_aops;
+
+               TRACE("File inode %x:%x, start_block %llx, block_list_start "
+                       "%llx, offset %x\n", SQUASHFS_INODE_BLK(ino),
+                       offset, squashfs_i(inode)->start, block, offset);
+               break;
+       }
+       case SQUASHFS_DIR_TYPE: {
+               struct squashfs_dir_inode *sqsh_ino = &squashfs_ino.dir;
+
+               err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
+                               sizeof(*sqsh_ino));
+               if (err < 0)
+                       goto failed_read;
+
+               inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
+               inode->i_size = le16_to_cpu(sqsh_ino->file_size);
+               inode->i_op = &squashfs_dir_inode_ops;
+               inode->i_fop = &squashfs_dir_ops;
+               inode->i_mode |= S_IFDIR;
+               squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
+               squashfs_i(inode)->offset = le16_to_cpu(sqsh_ino->offset);
+               squashfs_i(inode)->dir_idx_cnt = 0;
+               squashfs_i(inode)->parent = le32_to_cpu(sqsh_ino->parent_inode);
+
+               TRACE("Directory inode %x:%x, start_block %llx, offset %x\n",
+                               SQUASHFS_INODE_BLK(ino), offset,
+                               squashfs_i(inode)->start,
+                               le16_to_cpu(sqsh_ino->offset));
+               break;
+       }
+       case SQUASHFS_LDIR_TYPE: {
+               struct squashfs_ldir_inode *sqsh_ino = &squashfs_ino.ldir;
+
+               err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
+                               sizeof(*sqsh_ino));
+               if (err < 0)
+                       goto failed_read;
+
+               inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
+               inode->i_size = le32_to_cpu(sqsh_ino->file_size);
+               inode->i_op = &squashfs_dir_inode_ops;
+               inode->i_fop = &squashfs_dir_ops;
+               inode->i_mode |= S_IFDIR;
+               squashfs_i(inode)->start = le32_to_cpu(sqsh_ino->start_block);
+               squashfs_i(inode)->offset = le16_to_cpu(sqsh_ino->offset);
+               squashfs_i(inode)->dir_idx_start = block;
+               squashfs_i(inode)->dir_idx_offset = offset;
+               squashfs_i(inode)->dir_idx_cnt = le16_to_cpu(sqsh_ino->i_count);
+               squashfs_i(inode)->parent = le32_to_cpu(sqsh_ino->parent_inode);
+
+               TRACE("Long directory inode %x:%x, start_block %llx, offset "
+                               "%x\n", SQUASHFS_INODE_BLK(ino), offset,
+                               squashfs_i(inode)->start,
+                               le16_to_cpu(sqsh_ino->offset));
+               break;
+       }
+       case SQUASHFS_SYMLINK_TYPE:
+       case SQUASHFS_LSYMLINK_TYPE: {
+               struct squashfs_symlink_inode *sqsh_ino = &squashfs_ino.symlink;
+
+               err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
+                               sizeof(*sqsh_ino));
+               if (err < 0)
+                       goto failed_read;
+
+               inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
+               inode->i_size = le32_to_cpu(sqsh_ino->symlink_size);
+               inode->i_op = &page_symlink_inode_operations;
+               inode->i_data.a_ops = &squashfs_symlink_aops;
+               inode->i_mode |= S_IFLNK;
+               squashfs_i(inode)->start = block;
+               squashfs_i(inode)->offset = offset;
+
+               TRACE("Symbolic link inode %x:%x, start_block %llx, offset "
+                               "%x\n", SQUASHFS_INODE_BLK(ino), offset,
+                               block, offset);
+               break;
+       }
+       case SQUASHFS_BLKDEV_TYPE:
+       case SQUASHFS_CHRDEV_TYPE:
+       case SQUASHFS_LBLKDEV_TYPE:
+       case SQUASHFS_LCHRDEV_TYPE: {
+               struct squashfs_dev_inode *sqsh_ino = &squashfs_ino.dev;
+               unsigned int rdev;
+
+               err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
+                               sizeof(*sqsh_ino));
+               if (err < 0)
+                       goto failed_read;
+
+               if (type == SQUASHFS_CHRDEV_TYPE)
+                       inode->i_mode |= S_IFCHR;
+               else
+                       inode->i_mode |= S_IFBLK;
+               inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
+               rdev = le32_to_cpu(sqsh_ino->rdev);
+               init_special_inode(inode, inode->i_mode, new_decode_dev(rdev));
+
+               TRACE("Device inode %x:%x, rdev %x\n",
+                               SQUASHFS_INODE_BLK(ino), offset, rdev);
+               break;
+       }
+       case SQUASHFS_FIFO_TYPE:
+       case SQUASHFS_SOCKET_TYPE:
+       case SQUASHFS_LFIFO_TYPE:
+       case SQUASHFS_LSOCKET_TYPE: {
+               struct squashfs_ipc_inode *sqsh_ino = &squashfs_ino.ipc;
+
+               err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
+                               sizeof(*sqsh_ino));
+               if (err < 0)
+                       goto failed_read;
+
+               if (type == SQUASHFS_FIFO_TYPE)
+                       inode->i_mode |= S_IFIFO;
+               else
+                       inode->i_mode |= S_IFSOCK;
+               inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
+               init_special_inode(inode, inode->i_mode, 0);
+               break;
+       }
+       default:
+               ERROR("Unknown inode type %d in squashfs_iget!\n", type);
+               return -EINVAL;
+       }
+
+       return 0;
+
+failed_read:
+       ERROR("Unable to read inode 0x%llx\n", ino);
+       return err;
+}