/* * 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. * * super.c */ /* * This file implements code to read the superblock, read and initialise * in-memory structures at mount time, and all the VFS glue code to register * the filesystem. */ #include <linux/fs.h> #include <linux/vfs.h> #include <linux/slab.h> #include <linux/mutex.h> #include <linux/pagemap.h> #include <linux/init.h> #include <linux/module.h> #include <linux/zlib.h> #include <linux/magic.h> #include "squashfs_fs.h" #include "squashfs_fs_sb.h" #include "squashfs_fs_i.h" #include "squashfs.h" static struct file_system_type squashfs_fs_type; static struct super_operations squashfs_super_ops; static int supported_squashfs_filesystem(short major, short minor, short comp) { if (major < SQUASHFS_MAJOR) { ERROR("Major/Minor mismatch, older Squashfs %d.%d " "filesystems are unsupported\n", major, minor); return -EINVAL; } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) { ERROR("Major/Minor mismatch, trying to mount newer " "%d.%d filesystem\n", major, minor); ERROR("Please update your kernel\n"); return -EINVAL; } if (comp != ZLIB_COMPRESSION) return -EINVAL; return 0; } static int squashfs_fill_super(struct super_block *sb, void *data, int silent) { struct squashfs_sb_info *msblk; struct squashfs_super_block *sblk = NULL; char b[BDEVNAME_SIZE]; struct inode *root; long long root_inode; unsigned short flags; unsigned int fragments; u64 lookup_table_start; int err; TRACE("Entered squashfs_fill_superblock\n"); sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL); if (sb->s_fs_info == NULL) { ERROR("Failed to allocate squashfs_sb_info\n"); return -ENOMEM; } msblk = sb->s_fs_info; msblk->stream.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL); if (msblk->stream.workspace == NULL) { ERROR("Failed to allocate zlib workspace\n"); goto failure; } sblk = kzalloc(sizeof(*sblk), GFP_KERNEL); if (sblk == NULL) { ERROR("Failed to allocate squashfs_super_block\n"); goto failure; } msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE); msblk->devblksize_log2 = ffz(~msblk->devblksize); mutex_init(&msblk->read_data_mutex); mutex_init(&msblk->meta_index_mutex); /* * msblk->bytes_used is checked in squashfs_read_table to ensure reads * are not beyond filesystem end. But as we're using * squashfs_read_table here to read the superblock (including the value * of bytes_used) we need to set it to an initial sensible dummy value */ msblk->bytes_used = sizeof(*sblk); err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk)); if (err < 0) { ERROR("unable to read squashfs_super_block\n"); goto failed_mount; } /* Check it is a SQUASHFS superblock */ sb->s_magic = le32_to_cpu(sblk->s_magic); if (sb->s_magic != SQUASHFS_MAGIC) { if (!silent) ERROR("Can't find a SQUASHFS superblock on %s\n", bdevname(sb->s_bdev, b)); err = -EINVAL; goto failed_mount; } /* Check the MAJOR & MINOR versions and compression type */ err = supported_squashfs_filesystem(le16_to_cpu(sblk->s_major), le16_to_cpu(sblk->s_minor), le16_to_cpu(sblk->compression)); if (err < 0) goto failed_mount; err = -EINVAL; /* * Check if there's xattrs in the filesystem. These are not * supported in this version, so warn that they will be ignored. */ if (le64_to_cpu(sblk->xattr_table_start) != SQUASHFS_INVALID_BLK) ERROR("Xattrs in filesystem, these will be ignored\n"); /* Check the filesystem does not extend beyond the end of the block device */ msblk->bytes_used = le64_to_cpu(sblk->bytes_used); if (msblk->bytes_used < 0 || msblk->bytes_used > i_size_read(sb->s_bdev->bd_inode)) goto failed_mount; /* Check block size for sanity */ msblk->block_size = le32_to_cpu(sblk->block_size); if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE) goto failed_mount; msblk->block_log = le16_to_cpu(sblk->block_log); if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) goto failed_mount; /* Check the root inode for sanity */ root_inode = le64_to_cpu(sblk->root_inode); if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) goto failed_mount; msblk->inode_table = le64_to_cpu(sblk->inode_table_start); msblk->directory_table = le64_to_cpu(sblk->directory_table_start); msblk->inodes = le32_to_cpu(sblk->inodes); flags = le16_to_cpu(sblk->flags); TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b)); TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) ? "un" : ""); TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) ? "un" : ""); TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); TRACE("Block size %d\n", msblk->block_size); TRACE("Number of inodes %d\n", msblk->inodes); TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments)); TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids)); TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); TRACE("sblk->fragment_table_start %llx\n", (u64) le64_to_cpu(sblk->fragment_table_start)); TRACE("sblk->id_table_start %llx\n", (u64) le64_to_cpu(sblk->id_table_start)); sb->s_maxbytes = MAX_LFS_FILESIZE; sb->s_flags |= MS_RDONLY; sb->s_op = &squashfs_super_ops; err = -ENOMEM; msblk->block_cache = squashfs_cache_init("metadata", SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); if (msblk->block_cache == NULL) goto failed_mount; /* Allocate read_page block */ msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size); if (msblk->read_page == NULL) { ERROR("Failed to allocate read_page block\n"); goto failed_mount; } /* Allocate and read id index table */ msblk->id_table = squashfs_read_id_index_table(sb, le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids)); if (IS_ERR(msblk->id_table)) { err = PTR_ERR(msblk->id_table); msblk->id_table = NULL; goto failed_mount; } fragments = le32_to_cpu(sblk->fragments); if (fragments == 0) goto allocate_lookup_table; msblk->fragment_cache = squashfs_cache_init("fragment", SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); if (msblk->fragment_cache == NULL) { err = -ENOMEM; goto failed_mount; } /* Allocate and read fragment index table */ msblk->fragment_index = squashfs_read_fragment_index_table(sb, le64_to_cpu(sblk->fragment_table_start), fragments); if (IS_ERR(msblk->fragment_index)) { err = PTR_ERR(msblk->fragment_index); msblk->fragment_index = NULL; goto failed_mount; } allocate_lookup_table: lookup_table_start = le64_to_cpu(sblk->lookup_table_start); if (lookup_table_start == SQUASHFS_INVALID_BLK) goto allocate_root; /* Allocate and read inode lookup table */ msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, lookup_table_start, msblk->inodes); if (IS_ERR(msblk->inode_lookup_table)) { err = PTR_ERR(msblk->inode_lookup_table); msblk->inode_lookup_table = NULL; goto failed_mount; } sb->s_export_op = &squashfs_export_ops; allocate_root: root = new_inode(sb); if (!root) { err = -ENOMEM; goto failed_mount; } err = squashfs_read_inode(root, root_inode); if (err) { iget_failed(root); goto failed_mount; } insert_inode_hash(root); sb->s_root = d_alloc_root(root); if (sb->s_root == NULL) { ERROR("Root inode create failed\n"); err = -ENOMEM; iput(root); goto failed_mount; } TRACE("Leaving squashfs_fill_super\n"); kfree(sblk); return 0; failed_mount: squashfs_cache_delete(msblk->block_cache); squashfs_cache_delete(msblk->fragment_cache); squashfs_cache_delete(msblk->read_page); kfree(msblk->inode_lookup_table); kfree(msblk->fragment_index); kfree(msblk->id_table); kfree(msblk->stream.workspace); kfree(sb->s_fs_info); sb->s_fs_info = NULL; kfree(sblk); return err; failure: kfree(msblk->stream.workspace); kfree(sb->s_fs_info); sb->s_fs_info = NULL; return -ENOMEM; } static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) { struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; TRACE("Entered squashfs_statfs\n"); buf->f_type = SQUASHFS_MAGIC; buf->f_bsize = msblk->block_size; buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; buf->f_bfree = buf->f_bavail = 0; buf->f_files = msblk->inodes; buf->f_ffree = 0; buf->f_namelen = SQUASHFS_NAME_LEN; return 0; } static int squashfs_remount(struct super_block *sb, int *flags, char *data) { *flags |= MS_RDONLY; return 0; } static void squashfs_put_super(struct super_block *sb) { if (sb->s_fs_info) { struct squashfs_sb_info *sbi = sb->s_fs_info; squashfs_cache_delete(sbi->block_cache); squashfs_cache_delete(sbi->fragment_cache); squashfs_cache_delete(sbi->read_page); kfree(sbi->id_table); kfree(sbi->fragment_index); kfree(sbi->meta_index); kfree(sbi->stream.workspace); kfree(sb->s_fs_info); sb->s_fs_info = NULL; } } static int squashfs_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { return get_sb_bdev(fs_type, flags, dev_name, data, squashfs_fill_super, mnt); } static struct kmem_cache *squashfs_inode_cachep; static void init_once(void *foo) { struct squashfs_inode_info *ei = foo; inode_init_once(&ei->vfs_inode); } static int __init init_inodecache(void) { squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", sizeof(struct squashfs_inode_info), 0, SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once); return squashfs_inode_cachep ? 0 : -ENOMEM; } static void destroy_inodecache(void) { kmem_cache_destroy(squashfs_inode_cachep); } static int __init init_squashfs_fs(void) { int err = init_inodecache(); if (err) return err; err = register_filesystem(&squashfs_fs_type); if (err) { destroy_inodecache(); return err; } printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) " "Phillip Lougher\n"); return 0; } static void __exit exit_squashfs_fs(void) { unregister_filesystem(&squashfs_fs_type); destroy_inodecache(); } static struct inode *squashfs_alloc_inode(struct super_block *sb) { struct squashfs_inode_info *ei = kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); return ei ? &ei->vfs_inode : NULL; } static void squashfs_destroy_inode(struct inode *inode) { kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); } static struct file_system_type squashfs_fs_type = { .owner = THIS_MODULE, .name = "squashfs", .get_sb = squashfs_get_sb, .kill_sb = kill_block_super, .fs_flags = FS_REQUIRES_DEV }; static struct super_operations squashfs_super_ops = { .alloc_inode = squashfs_alloc_inode, .destroy_inode = squashfs_destroy_inode, .statfs = squashfs_statfs, .put_super = squashfs_put_super, .remount_fs = squashfs_remount }; module_init(init_squashfs_fs); module_exit(exit_squashfs_fs); MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>"); MODULE_LICENSE("GPL");