diff options
Diffstat (limited to 'fs/cramfs/inode.c')
| -rw-r--r-- | fs/cramfs/inode.c | 611 |
1 files changed, 611 insertions, 0 deletions
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c new file mode 100644 index 000000000..355c522f3 --- /dev/null +++ b/fs/cramfs/inode.c @@ -0,0 +1,611 @@ +/* + * Compressed rom filesystem for Linux. + * + * Copyright (C) 1999 Linus Torvalds. + * + * This file is released under the GPL. + */ + +/* + * These are the VFS interfaces to the compressed rom filesystem. + * The actual compression is based on zlib, see the other files. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/fs.h> +#include <linux/pagemap.h> +#include <linux/init.h> +#include <linux/string.h> +#include <linux/blkdev.h> +#include <linux/slab.h> +#include <linux/vfs.h> +#include <linux/mutex.h> +#include <uapi/linux/cramfs_fs.h> +#include <linux/uaccess.h> + +#include "internal.h" + +/* + * cramfs super-block data in memory + */ +struct cramfs_sb_info { + unsigned long magic; + unsigned long size; + unsigned long blocks; + unsigned long files; + unsigned long flags; +}; + +static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb) +{ + return sb->s_fs_info; +} + +static const struct super_operations cramfs_ops; +static const struct inode_operations cramfs_dir_inode_operations; +static const struct file_operations cramfs_directory_operations; +static const struct address_space_operations cramfs_aops; + +static DEFINE_MUTEX(read_mutex); + + +/* These macros may change in future, to provide better st_ino semantics. */ +#define OFFSET(x) ((x)->i_ino) + +static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset) +{ + if (!cino->offset) + return offset + 1; + if (!cino->size) + return offset + 1; + + /* + * The file mode test fixes buggy mkcramfs implementations where + * cramfs_inode->offset is set to a non zero value for entries + * which did not contain data, like devices node and fifos. + */ + switch (cino->mode & S_IFMT) { + case S_IFREG: + case S_IFDIR: + case S_IFLNK: + return cino->offset << 2; + default: + break; + } + return offset + 1; +} + +static struct inode *get_cramfs_inode(struct super_block *sb, + const struct cramfs_inode *cramfs_inode, unsigned int offset) +{ + struct inode *inode; + static struct timespec zerotime; + + inode = iget_locked(sb, cramino(cramfs_inode, offset)); + if (!inode) + return ERR_PTR(-ENOMEM); + if (!(inode->i_state & I_NEW)) + return inode; + + switch (cramfs_inode->mode & S_IFMT) { + case S_IFREG: + inode->i_fop = &generic_ro_fops; + inode->i_data.a_ops = &cramfs_aops; + break; + case S_IFDIR: + inode->i_op = &cramfs_dir_inode_operations; + inode->i_fop = &cramfs_directory_operations; + break; + case S_IFLNK: + inode->i_op = &page_symlink_inode_operations; + inode->i_data.a_ops = &cramfs_aops; + break; + default: + init_special_inode(inode, cramfs_inode->mode, + old_decode_dev(cramfs_inode->size)); + } + + inode->i_mode = cramfs_inode->mode; + i_uid_write(inode, cramfs_inode->uid); + i_gid_write(inode, cramfs_inode->gid); + + /* if the lower 2 bits are zero, the inode contains data */ + if (!(inode->i_ino & 3)) { + inode->i_size = cramfs_inode->size; + inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1; + } + + /* Struct copy intentional */ + inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime; + /* inode->i_nlink is left 1 - arguably wrong for directories, + but it's the best we can do without reading the directory + contents. 1 yields the right result in GNU find, even + without -noleaf option. */ + + unlock_new_inode(inode); + + return inode; +} + +/* + * We have our own block cache: don't fill up the buffer cache + * with the rom-image, because the way the filesystem is set + * up the accesses should be fairly regular and cached in the + * page cache and dentry tree anyway.. + * + * This also acts as a way to guarantee contiguous areas of up to + * BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to + * worry about end-of-buffer issues even when decompressing a full + * page cache. + */ +#define READ_BUFFERS (2) +/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */ +#define NEXT_BUFFER(_ix) ((_ix) ^ 1) + +/* + * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed" + * data that takes up more space than the original and with unlucky + * alignment. + */ +#define BLKS_PER_BUF_SHIFT (2) +#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT) +#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE) + +static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE]; +static unsigned buffer_blocknr[READ_BUFFERS]; +static struct super_block *buffer_dev[READ_BUFFERS]; +static int next_buffer; + +/* + * Returns a pointer to a buffer containing at least LEN bytes of + * filesystem starting at byte offset OFFSET into the filesystem. + */ +static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len) +{ + struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping; + struct page *pages[BLKS_PER_BUF]; + unsigned i, blocknr, buffer; + unsigned long devsize; + char *data; + + if (!len) + return NULL; + blocknr = offset >> PAGE_CACHE_SHIFT; + offset &= PAGE_CACHE_SIZE - 1; + + /* Check if an existing buffer already has the data.. */ + for (i = 0; i < READ_BUFFERS; i++) { + unsigned int blk_offset; + + if (buffer_dev[i] != sb) + continue; + if (blocknr < buffer_blocknr[i]) + continue; + blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT; + blk_offset += offset; + if (blk_offset + len > BUFFER_SIZE) + continue; + return read_buffers[i] + blk_offset; + } + + devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT; + + /* Ok, read in BLKS_PER_BUF pages completely first. */ + for (i = 0; i < BLKS_PER_BUF; i++) { + struct page *page = NULL; + + if (blocknr + i < devsize) { + page = read_mapping_page(mapping, blocknr + i, NULL); + /* synchronous error? */ + if (IS_ERR(page)) + page = NULL; + } + pages[i] = page; + } + + for (i = 0; i < BLKS_PER_BUF; i++) { + struct page *page = pages[i]; + + if (page) { + wait_on_page_locked(page); + if (!PageUptodate(page)) { + /* asynchronous error */ + page_cache_release(page); + pages[i] = NULL; + } + } + } + + buffer = next_buffer; + next_buffer = NEXT_BUFFER(buffer); + buffer_blocknr[buffer] = blocknr; + buffer_dev[buffer] = sb; + + data = read_buffers[buffer]; + for (i = 0; i < BLKS_PER_BUF; i++) { + struct page *page = pages[i]; + + if (page) { + memcpy(data, kmap(page), PAGE_CACHE_SIZE); + kunmap(page); + page_cache_release(page); + } else + memset(data, 0, PAGE_CACHE_SIZE); + data += PAGE_CACHE_SIZE; + } + return read_buffers[buffer] + offset; +} + +static void cramfs_kill_sb(struct super_block *sb) +{ + struct cramfs_sb_info *sbi = CRAMFS_SB(sb); + + kill_block_super(sb); + kfree(sbi); +} + +static int cramfs_remount(struct super_block *sb, int *flags, char *data) +{ + sync_filesystem(sb); + *flags |= MS_RDONLY; + return 0; +} + +static int cramfs_fill_super(struct super_block *sb, void *data, int silent) +{ + int i; + struct cramfs_super super; + unsigned long root_offset; + struct cramfs_sb_info *sbi; + struct inode *root; + + sb->s_flags |= MS_RDONLY; + + sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL); + if (!sbi) + return -ENOMEM; + sb->s_fs_info = sbi; + + /* Invalidate the read buffers on mount: think disk change.. */ + mutex_lock(&read_mutex); + for (i = 0; i < READ_BUFFERS; i++) + buffer_blocknr[i] = -1; + + /* Read the first block and get the superblock from it */ + memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super)); + mutex_unlock(&read_mutex); + + /* Do sanity checks on the superblock */ + if (super.magic != CRAMFS_MAGIC) { + /* check for wrong endianness */ + if (super.magic == CRAMFS_MAGIC_WEND) { + if (!silent) + pr_err("wrong endianness\n"); + return -EINVAL; + } + + /* check at 512 byte offset */ + mutex_lock(&read_mutex); + memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super)); + mutex_unlock(&read_mutex); + if (super.magic != CRAMFS_MAGIC) { + if (super.magic == CRAMFS_MAGIC_WEND && !silent) + pr_err("wrong endianness\n"); + else if (!silent) + pr_err("wrong magic\n"); + return -EINVAL; + } + } + + /* get feature flags first */ + if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) { + pr_err("unsupported filesystem features\n"); + return -EINVAL; + } + + /* Check that the root inode is in a sane state */ + if (!S_ISDIR(super.root.mode)) { + pr_err("root is not a directory\n"); + return -EINVAL; + } + /* correct strange, hard-coded permissions of mkcramfs */ + super.root.mode |= (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH); + + root_offset = super.root.offset << 2; + if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) { + sbi->size = super.size; + sbi->blocks = super.fsid.blocks; + sbi->files = super.fsid.files; + } else { + sbi->size = 1<<28; + sbi->blocks = 0; + sbi->files = 0; + } + sbi->magic = super.magic; + sbi->flags = super.flags; + if (root_offset == 0) + pr_info("empty filesystem"); + else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) && + ((root_offset != sizeof(struct cramfs_super)) && + (root_offset != 512 + sizeof(struct cramfs_super)))) + { + pr_err("bad root offset %lu\n", root_offset); + return -EINVAL; + } + + /* Set it all up.. */ + sb->s_op = &cramfs_ops; + root = get_cramfs_inode(sb, &super.root, 0); + if (IS_ERR(root)) + return PTR_ERR(root); + sb->s_root = d_make_root(root); + if (!sb->s_root) + return -ENOMEM; + return 0; +} + +static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf) +{ + struct super_block *sb = dentry->d_sb; + u64 id = huge_encode_dev(sb->s_bdev->bd_dev); + + buf->f_type = CRAMFS_MAGIC; + buf->f_bsize = PAGE_CACHE_SIZE; + buf->f_blocks = CRAMFS_SB(sb)->blocks; + buf->f_bfree = 0; + buf->f_bavail = 0; + buf->f_files = CRAMFS_SB(sb)->files; + buf->f_ffree = 0; + buf->f_fsid.val[0] = (u32)id; + buf->f_fsid.val[1] = (u32)(id >> 32); + buf->f_namelen = CRAMFS_MAXPATHLEN; + return 0; +} + +/* + * Read a cramfs directory entry. + */ +static int cramfs_readdir(struct file *file, struct dir_context *ctx) +{ + struct inode *inode = file_inode(file); + struct super_block *sb = inode->i_sb; + char *buf; + unsigned int offset; + + /* Offset within the thing. */ + if (ctx->pos >= inode->i_size) + return 0; + offset = ctx->pos; + /* Directory entries are always 4-byte aligned */ + if (offset & 3) + return -EINVAL; + + buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + while (offset < inode->i_size) { + struct cramfs_inode *de; + unsigned long nextoffset; + char *name; + ino_t ino; + umode_t mode; + int namelen; + + mutex_lock(&read_mutex); + de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN); + name = (char *)(de+1); + + /* + * Namelengths on disk are shifted by two + * and the name padded out to 4-byte boundaries + * with zeroes. + */ + namelen = de->namelen << 2; + memcpy(buf, name, namelen); + ino = cramino(de, OFFSET(inode) + offset); + mode = de->mode; + mutex_unlock(&read_mutex); + nextoffset = offset + sizeof(*de) + namelen; + for (;;) { + if (!namelen) { + kfree(buf); + return -EIO; + } + if (buf[namelen-1]) + break; + namelen--; + } + if (!dir_emit(ctx, buf, namelen, ino, mode >> 12)) + break; + + ctx->pos = offset = nextoffset; + } + kfree(buf); + return 0; +} + +/* + * Lookup and fill in the inode data.. + */ +static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) +{ + unsigned int offset = 0; + struct inode *inode = NULL; + int sorted; + + mutex_lock(&read_mutex); + sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS; + while (offset < dir->i_size) { + struct cramfs_inode *de; + char *name; + int namelen, retval; + int dir_off = OFFSET(dir) + offset; + + de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN); + name = (char *)(de+1); + + /* Try to take advantage of sorted directories */ + if (sorted && (dentry->d_name.name[0] < name[0])) + break; + + namelen = de->namelen << 2; + offset += sizeof(*de) + namelen; + + /* Quick check that the name is roughly the right length */ + if (((dentry->d_name.len + 3) & ~3) != namelen) + continue; + + for (;;) { + if (!namelen) { + inode = ERR_PTR(-EIO); + goto out; + } + if (name[namelen-1]) + break; + namelen--; + } + if (namelen != dentry->d_name.len) + continue; + retval = memcmp(dentry->d_name.name, name, namelen); + if (retval > 0) + continue; + if (!retval) { + inode = get_cramfs_inode(dir->i_sb, de, dir_off); + break; + } + /* else (retval < 0) */ + if (sorted) + break; + } +out: + mutex_unlock(&read_mutex); + if (IS_ERR(inode)) + return ERR_CAST(inode); + d_add(dentry, inode); + return NULL; +} + +static int cramfs_readpage(struct file *file, struct page *page) +{ + struct inode *inode = page->mapping->host; + u32 maxblock; + int bytes_filled; + void *pgdata; + + maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; + bytes_filled = 0; + pgdata = kmap(page); + + if (page->index < maxblock) { + struct super_block *sb = inode->i_sb; + u32 blkptr_offset = OFFSET(inode) + page->index*4; + u32 start_offset, compr_len; + + start_offset = OFFSET(inode) + maxblock*4; + mutex_lock(&read_mutex); + if (page->index) + start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4, + 4); + compr_len = (*(u32 *) cramfs_read(sb, blkptr_offset, 4) - + start_offset); + mutex_unlock(&read_mutex); + + if (compr_len == 0) + ; /* hole */ + else if (unlikely(compr_len > (PAGE_CACHE_SIZE << 1))) { + pr_err("bad compressed blocksize %u\n", + compr_len); + goto err; + } else { + mutex_lock(&read_mutex); + bytes_filled = cramfs_uncompress_block(pgdata, + PAGE_CACHE_SIZE, + cramfs_read(sb, start_offset, compr_len), + compr_len); + mutex_unlock(&read_mutex); + if (unlikely(bytes_filled < 0)) + goto err; + } + } + + memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled); + flush_dcache_page(page); + kunmap(page); + SetPageUptodate(page); + unlock_page(page); + return 0; + +err: + kunmap(page); + ClearPageUptodate(page); + SetPageError(page); + unlock_page(page); + return 0; +} + +static const struct address_space_operations cramfs_aops = { + .readpage = cramfs_readpage +}; + +/* + * Our operations: + */ + +/* + * A directory can only readdir + */ +static const struct file_operations cramfs_directory_operations = { + .llseek = generic_file_llseek, + .read = generic_read_dir, + .iterate = cramfs_readdir, +}; + +static const struct inode_operations cramfs_dir_inode_operations = { + .lookup = cramfs_lookup, +}; + +static const struct super_operations cramfs_ops = { + .remount_fs = cramfs_remount, + .statfs = cramfs_statfs, +}; + +static struct dentry *cramfs_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data) +{ + return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super); +} + +static struct file_system_type cramfs_fs_type = { + .owner = THIS_MODULE, + .name = "cramfs", + .mount = cramfs_mount, + .kill_sb = cramfs_kill_sb, + .fs_flags = FS_REQUIRES_DEV, +}; +MODULE_ALIAS_FS("cramfs"); + +static int __init init_cramfs_fs(void) +{ + int rv; + + rv = cramfs_uncompress_init(); + if (rv < 0) + return rv; + rv = register_filesystem(&cramfs_fs_type); + if (rv < 0) + cramfs_uncompress_exit(); + return rv; +} + +static void __exit exit_cramfs_fs(void) +{ + cramfs_uncompress_exit(); + unregister_filesystem(&cramfs_fs_type); +} + +module_init(init_cramfs_fs) +module_exit(exit_cramfs_fs) +MODULE_LICENSE("GPL"); |