123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613 |
- /*
- * 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_nohighmem(inode);
- 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_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_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_SHIFT;
- offset &= PAGE_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_SHIFT;
- blk_offset += offset;
- if (blk_offset + len > BUFFER_SIZE)
- continue;
- return read_buffers[i] + blk_offset;
- }
- devsize = mapping->host->i_size >> PAGE_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 */
- put_page(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_SIZE);
- kunmap(page);
- put_page(page);
- } else
- memset(data, 0, PAGE_SIZE);
- data += PAGE_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_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_SIZE - 1) >> PAGE_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_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_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_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_shared = 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");
|