Squashfs: inode operations

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

1 files changed, 346 insertions, 0 deletions

diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c
new file mode 100644
index 000000000000..7a63398bb855
--- /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;
+}