--- /dev/null
+/*
+ * 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");
Code Review / kvmfornfv.git / blobdiff