diff options
Diffstat (limited to 'fs/squashfs/super.c')
| -rw-r--r-- | fs/squashfs/super.c | 508 |
1 files changed, 508 insertions, 0 deletions
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c new file mode 100644 index 000000000..5056babe0 --- /dev/null +++ b/fs/squashfs/super.c @@ -0,0 +1,508 @@ +/* + * Squashfs - a compressed read only filesystem for Linux + * + * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 + * Phillip Lougher <phillip@squashfs.org.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. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#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/magic.h> +#include <linux/xattr.h> + +#include "squashfs_fs.h" +#include "squashfs_fs_sb.h" +#include "squashfs_fs_i.h" +#include "squashfs.h" +#include "decompressor.h" +#include "xattr.h" + +static struct file_system_type squashfs_fs_type; +static const struct super_operations squashfs_super_ops; + +static const struct squashfs_decompressor *supported_squashfs_filesystem(short + major, short minor, short id) +{ + const struct squashfs_decompressor *decompressor; + + if (major < SQUASHFS_MAJOR) { + ERROR("Major/Minor mismatch, older Squashfs %d.%d " + "filesystems are unsupported\n", major, minor); + return NULL; + } 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 NULL; + } + + decompressor = squashfs_lookup_decompressor(id); + if (!decompressor->supported) { + ERROR("Filesystem uses \"%s\" compression. This is not " + "supported\n", decompressor->name); + return NULL; + } + + return decompressor; +} + + +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, xattr_id_table_start, next_table; + 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->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); + msblk->devblksize_log2 = ffz(~msblk->devblksize); + + 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); + sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk)); + + if (IS_ERR(sblk)) { + ERROR("unable to read squashfs_super_block\n"); + err = PTR_ERR(sblk); + sblk = NULL; + goto failed_mount; + } + + err = -EINVAL; + + /* 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)); + goto failed_mount; + } + + /* Check the MAJOR & MINOR versions and lookup compression type */ + msblk->decompressor = supported_squashfs_filesystem( + le16_to_cpu(sblk->s_major), + le16_to_cpu(sblk->s_minor), + le16_to_cpu(sblk->compression)); + if (msblk->decompressor == NULL) + goto failed_mount; + + /* 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; + + /* + * Check the system page size is not larger than the filesystem + * block size (by default 128K). This is currently not supported. + */ + if (PAGE_CACHE_SIZE > msblk->block_size) { + ERROR("Page size > filesystem block size (%d). This is " + "currently not supported!\n", msblk->block_size); + goto failed_mount; + } + + /* Check block log for sanity */ + msblk->block_log = le16_to_cpu(sblk->block_log); + if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) + goto failed_mount; + + /* Check that block_size and block_log match */ + if (msblk->block_size != (1 << msblk->block_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", + squashfs_max_decompressors(), msblk->block_size); + if (msblk->read_page == NULL) { + ERROR("Failed to allocate read_page block\n"); + goto failed_mount; + } + + msblk->stream = squashfs_decompressor_setup(sb, flags); + if (IS_ERR(msblk->stream)) { + err = PTR_ERR(msblk->stream); + msblk->stream = NULL; + goto failed_mount; + } + + /* Handle xattrs */ + sb->s_xattr = squashfs_xattr_handlers; + xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start); + if (xattr_id_table_start == SQUASHFS_INVALID_BLK) { + next_table = msblk->bytes_used; + goto allocate_id_index_table; + } + + /* Allocate and read xattr id lookup table */ + msblk->xattr_id_table = squashfs_read_xattr_id_table(sb, + xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids); + if (IS_ERR(msblk->xattr_id_table)) { + ERROR("unable to read xattr id index table\n"); + err = PTR_ERR(msblk->xattr_id_table); + msblk->xattr_id_table = NULL; + if (err != -ENOTSUPP) + goto failed_mount; + } + next_table = msblk->xattr_table; + +allocate_id_index_table: + /* Allocate and read id index table */ + msblk->id_table = squashfs_read_id_index_table(sb, + le64_to_cpu(sblk->id_table_start), next_table, + le16_to_cpu(sblk->no_ids)); + if (IS_ERR(msblk->id_table)) { + ERROR("unable to read id index table\n"); + err = PTR_ERR(msblk->id_table); + msblk->id_table = NULL; + goto failed_mount; + } + next_table = le64_to_cpu(msblk->id_table[0]); + + /* Handle inode lookup table */ + lookup_table_start = le64_to_cpu(sblk->lookup_table_start); + if (lookup_table_start == SQUASHFS_INVALID_BLK) + goto handle_fragments; + + /* Allocate and read inode lookup table */ + msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, + lookup_table_start, next_table, msblk->inodes); + if (IS_ERR(msblk->inode_lookup_table)) { + ERROR("unable to read inode lookup table\n"); + err = PTR_ERR(msblk->inode_lookup_table); + msblk->inode_lookup_table = NULL; + goto failed_mount; + } + next_table = le64_to_cpu(msblk->inode_lookup_table[0]); + + sb->s_export_op = &squashfs_export_ops; + +handle_fragments: + fragments = le32_to_cpu(sblk->fragments); + if (fragments == 0) + goto check_directory_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), next_table, fragments); + if (IS_ERR(msblk->fragment_index)) { + ERROR("unable to read fragment index table\n"); + err = PTR_ERR(msblk->fragment_index); + msblk->fragment_index = NULL; + goto failed_mount; + } + next_table = le64_to_cpu(msblk->fragment_index[0]); + +check_directory_table: + /* Sanity check directory_table */ + if (msblk->directory_table > next_table) { + err = -EINVAL; + goto failed_mount; + } + + /* Sanity check inode_table */ + if (msblk->inode_table >= msblk->directory_table) { + err = -EINVAL; + goto failed_mount; + } + + /* allocate root */ + root = new_inode(sb); + if (!root) { + err = -ENOMEM; + goto failed_mount; + } + + err = squashfs_read_inode(root, root_inode); + if (err) { + make_bad_inode(root); + iput(root); + goto failed_mount; + } + insert_inode_hash(root); + + sb->s_root = d_make_root(root); + if (sb->s_root == NULL) { + ERROR("Root inode create failed\n"); + err = -ENOMEM; + 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); + squashfs_decompressor_destroy(msblk); + kfree(msblk->inode_lookup_table); + kfree(msblk->fragment_index); + kfree(msblk->id_table); + kfree(msblk->xattr_id_table); + kfree(sb->s_fs_info); + sb->s_fs_info = NULL; + kfree(sblk); + return err; +} + + +static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) +{ + struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; + u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev); + + 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; + buf->f_fsid.val[0] = (u32)id; + buf->f_fsid.val[1] = (u32)(id >> 32); + + return 0; +} + + +static int squashfs_remount(struct super_block *sb, int *flags, char *data) +{ + sync_filesystem(sb); + *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); + squashfs_decompressor_destroy(sbi); + kfree(sbi->id_table); + kfree(sbi->fragment_index); + kfree(sbi->meta_index); + kfree(sbi->inode_lookup_table); + kfree(sbi->xattr_id_table); + kfree(sb->s_fs_info); + sb->s_fs_info = NULL; + } +} + + +static struct dentry *squashfs_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data) +{ + return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super); +} + + +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) +{ + /* + * Make sure all delayed rcu free inodes are flushed before we + * destroy cache. + */ + rcu_barrier(); + 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; + } + + pr_info("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_i_callback(struct rcu_head *head) +{ + struct inode *inode = container_of(head, struct inode, i_rcu); + kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); +} + +static void squashfs_destroy_inode(struct inode *inode) +{ + call_rcu(&inode->i_rcu, squashfs_i_callback); +} + + +static struct file_system_type squashfs_fs_type = { + .owner = THIS_MODULE, + .name = "squashfs", + .mount = squashfs_mount, + .kill_sb = kill_block_super, + .fs_flags = FS_REQUIRES_DEV +}; +MODULE_ALIAS_FS("squashfs"); + +static const 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@squashfs.org.uk>"); +MODULE_LICENSE("GPL"); |