[deliverable/linux.git] / fs / cramfs / inode.c

/*
 * 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.
 */

#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/cramfs_fs.h>
#include <linux/slab.h>
#include <linux/cramfs_fs_sb.h>
#include <linux/buffer_head.h>
#include <linux/vfs.h>
#include <linux/mutex.h>

#include <asm/uaccess.h>

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(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,
	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;
	inode->i_uid = cramfs_inode->uid;
	inode->i_gid = 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_async(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_put_super(struct super_block *sb)
{
	kfree(sb->s_fs_info);
	sb->s_fs_info = NULL;
}

static int cramfs_remount(struct super_block *sb, int *flags, char *data)
{
	*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 endianess */
		if (super.magic == CRAMFS_MAGIC_WEND) {
			if (!silent)
				printk(KERN_ERR "cramfs: wrong endianess\n");
			goto out;
		}

		/* 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)
				printk(KERN_ERR "cramfs: wrong endianess\n");
			else if (!silent)
				printk(KERN_ERR "cramfs: wrong magic\n");
			goto out;
		}
	}

	/* get feature flags first */
	if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
		printk(KERN_ERR "cramfs: unsupported filesystem features\n");
		goto out;
	}

	/* Check that the root inode is in a sane state */
	if (!S_ISDIR(super.root.mode)) {
		printk(KERN_ERR "cramfs: root is not a directory\n");
		goto out;
	}
	/* 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)
		printk(KERN_INFO "cramfs: empty filesystem");
	else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
		 ((root_offset != sizeof(struct cramfs_super)) &&
		  (root_offset != 512 + sizeof(struct cramfs_super))))
	{
		printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
		goto out;
	}

	/* Set it all up.. */
	sb->s_op = &cramfs_ops;
	root = get_cramfs_inode(sb, &super.root, 0);
	if (!root)
		goto out;
	sb->s_root = d_alloc_root(root);
	if (!sb->s_root) {
		iput(root);
		goto out;
	}
	return 0;
out:
	kfree(sbi);
	sb->s_fs_info = NULL;
	return -EINVAL;
}

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 *filp, void *dirent, filldir_t filldir)
{
	struct inode *inode = filp->f_path.dentry->d_inode;
	struct super_block *sb = inode->i_sb;
	char *buf;
	unsigned int offset;
	int copied;

	/* Offset within the thing. */
	offset = filp->f_pos;
	if (offset >= inode->i_size)
		return 0;
	/* Directory entries are always 4-byte aligned */
	if (offset & 3)
		return -EINVAL;

	buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	copied = 0;
	while (offset < inode->i_size) {
		struct cramfs_inode *de;
		unsigned long nextoffset;
		char *name;
		ino_t ino;
		mode_t mode;
		int namelen, error;

		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--;
		}
		error = filldir(dirent, buf, namelen, offset, ino, mode >> 12);
		if (error)
			break;

		offset = nextoffset;
		filp->f_pos = offset;
		copied++;
	}
	kfree(buf);
	return 0;
}

/*
 * Lookup and fill in the inode data..
 */
static struct dentry * cramfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
	unsigned int offset = 0;
	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) {
				mutex_unlock(&read_mutex);
				return ERR_PTR(-EIO);
			}
			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) {
			struct cramfs_inode entry = *de;
			mutex_unlock(&read_mutex);
			d_add(dentry, get_cramfs_inode(dir->i_sb, &entry, dir_off));
			return NULL;
		}
		/* else (retval < 0) */
		if (sorted)
			break;
	}
	mutex_unlock(&read_mutex);
	d_add(dentry, NULL);
	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("cramfs: 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,
	.readdir	= cramfs_readdir,
};

static const struct inode_operations cramfs_dir_inode_operations = {
	.lookup		= cramfs_lookup,
};

static const struct super_operations cramfs_ops = {
	.put_super	= cramfs_put_super,
	.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	= kill_block_super,
	.fs_flags	= FS_REQUIRES_DEV,
};

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");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Compressed rom filesystem for Linux.
	3	*
	4	* Copyright (C) 1999 Linus Torvalds.
	5	*
	6	* This file is released under the GPL.
	7	*/
	8
	9	/*
	10	* These are the VFS interfaces to the compressed rom filesystem.
	11	* The actual compression is based on zlib, see the other files.
	12	*/
	13
	14	#include <linux/module.h>
	15	#include <linux/fs.h>
	16	#include <linux/pagemap.h>
	17	#include <linux/init.h>
	18	#include <linux/string.h>
	19	#include <linux/blkdev.h>
	20	#include <linux/cramfs_fs.h>
	21	#include <linux/slab.h>
	22	#include <linux/cramfs_fs_sb.h>
	23	#include <linux/buffer_head.h>
	24	#include <linux/vfs.h>
353ab6e9	25	#include <linux/mutex.h>
1da177e4 LT	26
	27	#include <asm/uaccess.h>
	28
ee9b6d61	29	static const struct super_operations cramfs_ops;
754661f1	30	static const struct inode_operations cramfs_dir_inode_operations;
4b6f5d20	31	static const struct file_operations cramfs_directory_operations;
f5e54d6e	32	static const struct address_space_operations cramfs_aops;
1da177e4	33
353ab6e9	34	static DEFINE_MUTEX(read_mutex);
1da177e4 LT	35
1da177e4 LT	36
6f772fe6	37	/* These macros may change in future, to provide better st_ino semantics. */
1da177e4 LT	38	#define OFFSET(x) ((x)->i_ino)
1da177e4 LT	39
6f772fe6	40	static unsigned long cramino(struct cramfs_inode *cino, unsigned int offset)
a97c9bf3	41	{
6f772fe6 SS	42	if (!cino->offset)
	43	return offset + 1;
	44	if (!cino->size)
	45	return offset + 1;
	46
	47	/*
	48	* The file mode test fixes buggy mkcramfs implementations where
	49	* cramfs_inode->offset is set to a non zero value for entries
	50	* which did not contain data, like devices node and fifos.
	51	*/
	52	switch (cino->mode & S_IFMT) {
	53	case S_IFREG:
	54	case S_IFDIR:
	55	case S_IFLNK:
	56	return cino->offset << 2;
	57	default:
	58	break;
	59	}
	60	return offset + 1;
	61	}
	62
	63	static struct inode get_cramfs_inode(struct super_block sb,
	64	struct cramfs_inode *cramfs_inode, unsigned int offset)
	65	{
	66	struct inode *inode;
77b8a75f	67	static struct timespec zerotime;
6f772fe6 SS	68
	69	inode = iget_locked(sb, cramino(cramfs_inode, offset));
	70	if (!inode)
	71	return ERR_PTR(-ENOMEM);
	72	if (!(inode->i_state & I_NEW))
	73	return inode;
	74
	75	switch (cramfs_inode->mode & S_IFMT) {
	76	case S_IFREG:
	77	inode->i_fop = &generic_ro_fops;
	78	inode->i_data.a_ops = &cramfs_aops;
	79	break;
	80	case S_IFDIR:
	81	inode->i_op = &cramfs_dir_inode_operations;
	82	inode->i_fop = &cramfs_directory_operations;
	83	break;
	84	case S_IFLNK:
	85	inode->i_op = &page_symlink_inode_operations;
	86	inode->i_data.a_ops = &cramfs_aops;
	87	break;
	88	default:
	89	init_special_inode(inode, cramfs_inode->mode,
	90	old_decode_dev(cramfs_inode->size));
	91	}
	92
77b8a75f AV	93	inode->i_mode = cramfs_inode->mode;
77b8a75f AV	94	inode->i_uid = cramfs_inode->uid;
77b8a75f	95	inode->i_gid = cramfs_inode->gid;
6f772fe6 SS	96
	97	/* if the lower 2 bits are zero, the inode contains data */
	98	if (!(inode->i_ino & 3)) {
	99	inode->i_size = cramfs_inode->size;
	100	inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
	101	}
	102
77b8a75f AV	103	/* Struct copy intentional */
	104	inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
	105	/* inode->i_nlink is left 1 - arguably wrong for directories,
	106	but it's the best we can do without reading the directory
	107	contents. 1 yields the right result in GNU find, even
	108	without -noleaf option. */
a97c9bf3	109
6f772fe6 SS	110	unlock_new_inode(inode);
6f772fe6 SS	111
1da177e4 LT	112	return inode;
	113	}
	114
	115	/*
	116	* We have our own block cache: don't fill up the buffer cache
	117	* with the rom-image, because the way the filesystem is set
	118	* up the accesses should be fairly regular and cached in the
	119	* page cache and dentry tree anyway..
	120	*
	121	* This also acts as a way to guarantee contiguous areas of up to
	122	* BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to
	123	* worry about end-of-buffer issues even when decompressing a full
	124	* page cache.
	125	*/
	126	#define READ_BUFFERS (2)
	127	/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
	128	#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
	129
	130	/*
	131	* BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
	132	* data that takes up more space than the original and with unlucky
	133	* alignment.
	134	*/
	135	#define BLKS_PER_BUF_SHIFT (2)
	136	#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
	137	#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE)
	138
	139	static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
	140	static unsigned buffer_blocknr[READ_BUFFERS];
	141	static struct super_block * buffer_dev[READ_BUFFERS];
	142	static int next_buffer;
	143
	144	/*
	145	* Returns a pointer to a buffer containing at least LEN bytes of
	146	* filesystem starting at byte offset OFFSET into the filesystem.
	147	*/
	148	static void cramfs_read(struct super_block sb, unsigned int offset, unsigned int len)
	149	{
	150	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
	151	struct page *pages[BLKS_PER_BUF];
6bbfb077	152	unsigned i, blocknr, buffer;
1da177e4 LT	153	unsigned long devsize;
	154	char *data;
	155
	156	if (!len)
	157	return NULL;
	158	blocknr = offset >> PAGE_CACHE_SHIFT;
	159	offset &= PAGE_CACHE_SIZE - 1;
	160
	161	/* Check if an existing buffer already has the data.. */
	162	for (i = 0; i < READ_BUFFERS; i++) {
	163	unsigned int blk_offset;
	164
	165	if (buffer_dev[i] != sb)
	166	continue;
	167	if (blocknr < buffer_blocknr[i])
	168	continue;
	169	blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
	170	blk_offset += offset;
	171	if (blk_offset + len > BUFFER_SIZE)
	172	continue;
	173	return read_buffers[i] + blk_offset;
	174	}
	175
	176	devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
	177
	178	/* Ok, read in BLKS_PER_BUF pages completely first. */
1da177e4 LT	179	for (i = 0; i < BLKS_PER_BUF; i++) {
	180	struct page *page = NULL;
	181
	182	if (blocknr + i < devsize) {
6fe6900e NP	183	page = read_mapping_page_async(mapping, blocknr + i,
6fe6900e NP	184	NULL);
1da177e4 LT	185	/* synchronous error? */
	186	if (IS_ERR(page))
	187	page = NULL;
	188	}
	189	pages[i] = page;
	190	}
	191
	192	for (i = 0; i < BLKS_PER_BUF; i++) {
	193	struct page *page = pages[i];
	194	if (page) {
	195	wait_on_page_locked(page);
	196	if (!PageUptodate(page)) {
	197	/* asynchronous error */
	198	page_cache_release(page);
	199	pages[i] = NULL;
	200	}
	201	}
	202	}
	203
	204	buffer = next_buffer;
	205	next_buffer = NEXT_BUFFER(buffer);
	206	buffer_blocknr[buffer] = blocknr;
	207	buffer_dev[buffer] = sb;
	208
	209	data = read_buffers[buffer];
	210	for (i = 0; i < BLKS_PER_BUF; i++) {
	211	struct page *page = pages[i];
	212	if (page) {
	213	memcpy(data, kmap(page), PAGE_CACHE_SIZE);
	214	kunmap(page);
	215	page_cache_release(page);
	216	} else
	217	memset(data, 0, PAGE_CACHE_SIZE);
	218	data += PAGE_CACHE_SIZE;
	219	}
	220	return read_buffers[buffer] + offset;
	221	}
	222
	223	static void cramfs_put_super(struct super_block *sb)
	224	{
	225	kfree(sb->s_fs_info);
	226	sb->s_fs_info = NULL;
	227	}
	228
	229	static int cramfs_remount(struct super_block sb, int flags, char *data)
	230	{
	231	*flags \|= MS_RDONLY;
	232	return 0;
	233	}
	234
	235	static int cramfs_fill_super(struct super_block sb, void data, int silent)
	236	{
	237	int i;
	238	struct cramfs_super super;
	239	unsigned long root_offset;
	240	struct cramfs_sb_info *sbi;
	241	struct inode *root;
	242
	243	sb->s_flags \|= MS_RDONLY;
	244
f8314dc6	245	sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
1da177e4 LT	246	if (!sbi)
	247	return -ENOMEM;
	248	sb->s_fs_info = sbi;
1da177e4 LT	249
1da177e4 LT	250	/* Invalidate the read buffers on mount: think disk change.. */
353ab6e9	251	mutex_lock(&read_mutex);
1da177e4 LT	252	for (i = 0; i < READ_BUFFERS; i++)
	253	buffer_blocknr[i] = -1;
	254
	255	/* Read the first block and get the superblock from it */
	256	memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
353ab6e9	257	mutex_unlock(&read_mutex);
1da177e4 LT	258
	259	/* Do sanity checks on the superblock */
	260	if (super.magic != CRAMFS_MAGIC) {
ac8d35c5 AD	261	/* check for wrong endianess */
	262	if (super.magic == CRAMFS_MAGIC_WEND) {
	263	if (!silent)
	264	printk(KERN_ERR "cramfs: wrong endianess\n");
	265	goto out;
	266	}
	267
1da177e4	268	/* check at 512 byte offset */
353ab6e9	269	mutex_lock(&read_mutex);
1da177e4	270	memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
353ab6e9	271	mutex_unlock(&read_mutex);
1da177e4	272	if (super.magic != CRAMFS_MAGIC) {
ac8d35c5 AD	273	if (super.magic == CRAMFS_MAGIC_WEND && !silent)
	274	printk(KERN_ERR "cramfs: wrong endianess\n");
	275	else if (!silent)
1da177e4 LT	276	printk(KERN_ERR "cramfs: wrong magic\n");
	277	goto out;
	278	}
	279	}
	280
	281	/* get feature flags first */
	282	if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
	283	printk(KERN_ERR "cramfs: unsupported filesystem features\n");
	284	goto out;
	285	}
	286
	287	/* Check that the root inode is in a sane state */
	288	if (!S_ISDIR(super.root.mode)) {
	289	printk(KERN_ERR "cramfs: root is not a directory\n");
	290	goto out;
	291	}
6f772fe6 SS	292	/* correct strange, hard-coded permissions of mkcramfs */
	293	super.root.mode \|= (S_IRUSR \| S_IXUSR \| S_IRGRP \| S_IXGRP \| S_IROTH \| S_IXOTH);
	294
1da177e4 LT	295	root_offset = super.root.offset << 2;
	296	if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
	297	sbi->size=super.size;
	298	sbi->blocks=super.fsid.blocks;
	299	sbi->files=super.fsid.files;
	300	} else {
	301	sbi->size=1<<28;
	302	sbi->blocks=0;
	303	sbi->files=0;
	304	}
	305	sbi->magic=super.magic;
	306	sbi->flags=super.flags;
	307	if (root_offset == 0)
	308	printk(KERN_INFO "cramfs: empty filesystem");
	309	else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
	310	((root_offset != sizeof(struct cramfs_super)) &&
	311	(root_offset != 512 + sizeof(struct cramfs_super))))
	312	{
	313	printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
	314	goto out;
	315	}
	316
	317	/* Set it all up.. */
	318	sb->s_op = &cramfs_ops;
6f772fe6	319	root = get_cramfs_inode(sb, &super.root, 0);
1da177e4 LT	320	if (!root)
	321	goto out;
	322	sb->s_root = d_alloc_root(root);
	323	if (!sb->s_root) {
	324	iput(root);
	325	goto out;
	326	}
	327	return 0;
	328	out:
	329	kfree(sbi);
	330	sb->s_fs_info = NULL;
	331	return -EINVAL;
	332	}
	333
726c3342	334	static int cramfs_statfs(struct dentry dentry, struct kstatfs buf)
1da177e4	335	{
726c3342	336	struct super_block *sb = dentry->d_sb;
94ea77ac	337	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
726c3342	338
1da177e4 LT	339	buf->f_type = CRAMFS_MAGIC;
	340	buf->f_bsize = PAGE_CACHE_SIZE;
	341	buf->f_blocks = CRAMFS_SB(sb)->blocks;
	342	buf->f_bfree = 0;
	343	buf->f_bavail = 0;
	344	buf->f_files = CRAMFS_SB(sb)->files;
	345	buf->f_ffree = 0;
94ea77ac CL	346	buf->f_fsid.val[0] = (u32)id;
94ea77ac CL	347	buf->f_fsid.val[1] = (u32)(id >> 32);
1da177e4 LT	348	buf->f_namelen = CRAMFS_MAXPATHLEN;
	349	return 0;
	350	}
	351
	352	/*
	353	* Read a cramfs directory entry.
	354	*/
	355	static int cramfs_readdir(struct file filp, void dirent, filldir_t filldir)
	356	{
352d8af7	357	struct inode *inode = filp->f_path.dentry->d_inode;
1da177e4 LT	358	struct super_block *sb = inode->i_sb;
	359	char *buf;
	360	unsigned int offset;
	361	int copied;
	362
	363	/* Offset within the thing. */
	364	offset = filp->f_pos;
	365	if (offset >= inode->i_size)
	366	return 0;
	367	/* Directory entries are always 4-byte aligned */
	368	if (offset & 3)
	369	return -EINVAL;
	370
4176ed59	371	buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
1da177e4 LT	372	if (!buf)
	373	return -ENOMEM;
	374
	375	copied = 0;
	376	while (offset < inode->i_size) {
	377	struct cramfs_inode *de;
	378	unsigned long nextoffset;
	379	char *name;
	380	ino_t ino;
	381	mode_t mode;
	382	int namelen, error;
	383
353ab6e9	384	mutex_lock(&read_mutex);
4176ed59	385	de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
1da177e4 LT	386	name = (char *)(de+1);
	387
	388	/*
	389	* Namelengths on disk are shifted by two
	390	* and the name padded out to 4-byte boundaries
	391	* with zeroes.
	392	*/
	393	namelen = de->namelen << 2;
	394	memcpy(buf, name, namelen);
6f772fe6	395	ino = cramino(de, OFFSET(inode) + offset);
1da177e4	396	mode = de->mode;
353ab6e9	397	mutex_unlock(&read_mutex);
1da177e4 LT	398	nextoffset = offset + sizeof(*de) + namelen;
	399	for (;;) {
	400	if (!namelen) {
	401	kfree(buf);
	402	return -EIO;
	403	}
	404	if (buf[namelen-1])
	405	break;
	406	namelen--;
	407	}
	408	error = filldir(dirent, buf, namelen, offset, ino, mode >> 12);
	409	if (error)
	410	break;
	411
	412	offset = nextoffset;
	413	filp->f_pos = offset;
	414	copied++;
	415	}
	416	kfree(buf);
	417	return 0;
	418	}
	419
	420	/*
	421	* Lookup and fill in the inode data..
	422	*/
	423	static struct dentry * cramfs_lookup(struct inode dir, struct dentry dentry, struct nameidata *nd)
	424	{
	425	unsigned int offset = 0;
	426	int sorted;
	427
353ab6e9	428	mutex_lock(&read_mutex);
1da177e4 LT	429	sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
	430	while (offset < dir->i_size) {
	431	struct cramfs_inode *de;
	432	char *name;
	433	int namelen, retval;
6f772fe6	434	int dir_off = OFFSET(dir) + offset;
1da177e4	435
6f772fe6	436	de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
1da177e4 LT	437	name = (char *)(de+1);
	438
	439	/* Try to take advantage of sorted directories */
	440	if (sorted && (dentry->d_name.name[0] < name[0]))
	441	break;
	442
	443	namelen = de->namelen << 2;
	444	offset += sizeof(*de) + namelen;
	445
	446	/* Quick check that the name is roughly the right length */
	447	if (((dentry->d_name.len + 3) & ~3) != namelen)
	448	continue;
	449
	450	for (;;) {
	451	if (!namelen) {
353ab6e9	452	mutex_unlock(&read_mutex);
1da177e4 LT	453	return ERR_PTR(-EIO);
	454	}
	455	if (name[namelen-1])
	456	break;
	457	namelen--;
	458	}
	459	if (namelen != dentry->d_name.len)
	460	continue;
	461	retval = memcmp(dentry->d_name.name, name, namelen);
	462	if (retval > 0)
	463	continue;
	464	if (!retval) {
	465	struct cramfs_inode entry = *de;
353ab6e9	466	mutex_unlock(&read_mutex);
6f772fe6	467	d_add(dentry, get_cramfs_inode(dir->i_sb, &entry, dir_off));
1da177e4 LT	468	return NULL;
	469	}
	470	/* else (retval < 0) */
	471	if (sorted)
	472	break;
	473	}
353ab6e9	474	mutex_unlock(&read_mutex);
1da177e4 LT	475	d_add(dentry, NULL);
	476	return NULL;
	477	}
	478
	479	static int cramfs_readpage(struct file file, struct page page)
	480	{
	481	struct inode *inode = page->mapping->host;
98310e58 DV	482	u32 maxblock;
98310e58 DV	483	int bytes_filled;
1da177e4 LT	484	void *pgdata;
	485
	486	maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
	487	bytes_filled = 0;
98310e58 DV	488	pgdata = kmap(page);
98310e58 DV	489
1da177e4 LT	490	if (page->index < maxblock) {
	491	struct super_block *sb = inode->i_sb;
	492	u32 blkptr_offset = OFFSET(inode) + page->index*4;
	493	u32 start_offset, compr_len;
	494
	495	start_offset = OFFSET(inode) + maxblock*4;
353ab6e9	496	mutex_lock(&read_mutex);
1da177e4	497	if (page->index)
98310e58 DV	498	start_offset = (u32 ) cramfs_read(sb, blkptr_offset-4,
	499	4);
	500	compr_len = ((u32 ) cramfs_read(sb, blkptr_offset, 4) -
	501	start_offset);
353ab6e9	502	mutex_unlock(&read_mutex);
98310e58	503
1da177e4 LT	504	if (compr_len == 0)
1da177e4 LT	505	; /* hole */
98310e58 DV	506	else if (unlikely(compr_len > (PAGE_CACHE_SIZE << 1))) {
	507	pr_err("cramfs: bad compressed blocksize %u\n",
	508	compr_len);
	509	goto err;
	510	} else {
353ab6e9	511	mutex_lock(&read_mutex);
1da177e4 LT	512	bytes_filled = cramfs_uncompress_block(pgdata,
	513	PAGE_CACHE_SIZE,
	514	cramfs_read(sb, start_offset, compr_len),
	515	compr_len);
353ab6e9	516	mutex_unlock(&read_mutex);
98310e58 DV	517	if (unlikely(bytes_filled < 0))
98310e58 DV	518	goto err;
1da177e4	519	}
98310e58 DV	520	}
98310e58 DV	521
1da177e4	522	memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
1da177e4	523	flush_dcache_page(page);
98310e58	524	kunmap(page);
1da177e4 LT	525	SetPageUptodate(page);
	526	unlock_page(page);
	527	return 0;
98310e58 DV	528
	529	err:
	530	kunmap(page);
	531	ClearPageUptodate(page);
	532	SetPageError(page);
	533	unlock_page(page);
	534	return 0;
1da177e4 LT	535	}
1da177e4 LT	536
f5e54d6e	537	static const struct address_space_operations cramfs_aops = {
1da177e4 LT	538	.readpage = cramfs_readpage
	539	};
	540
	541	/*
	542	* Our operations:
	543	*/
	544
	545	/*
	546	* A directory can only readdir
	547	*/
4b6f5d20	548	static const struct file_operations cramfs_directory_operations = {
1da177e4 LT	549	.llseek = generic_file_llseek,
	550	.read = generic_read_dir,
	551	.readdir = cramfs_readdir,
	552	};
	553
754661f1	554	static const struct inode_operations cramfs_dir_inode_operations = {
1da177e4 LT	555	.lookup = cramfs_lookup,
	556	};
	557
ee9b6d61	558	static const struct super_operations cramfs_ops = {
1da177e4 LT	559	.put_super = cramfs_put_super,
	560	.remount_fs = cramfs_remount,
	561	.statfs = cramfs_statfs,
	562	};
	563
152a0836 AV	564	static struct dentry cramfs_mount(struct file_system_type fs_type,
152a0836 AV	565	int flags, const char dev_name, void data)
1da177e4	566	{
152a0836	567	return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
1da177e4 LT	568	}
	569
	570	static struct file_system_type cramfs_fs_type = {
	571	.owner = THIS_MODULE,
	572	.name = "cramfs",
152a0836	573	.mount = cramfs_mount,
1da177e4 LT	574	.kill_sb = kill_block_super,
	575	.fs_flags = FS_REQUIRES_DEV,
	576	};
	577
	578	static int __init init_cramfs_fs(void)
	579	{
50d44ed0 AD	580	int rv;
	581
	582	rv = cramfs_uncompress_init();
	583	if (rv < 0)
	584	return rv;
	585	rv = register_filesystem(&cramfs_fs_type);
	586	if (rv < 0)
	587	cramfs_uncompress_exit();
	588	return rv;
1da177e4 LT	589	}
	590
	591	static void __exit exit_cramfs_fs(void)
	592	{
	593	cramfs_uncompress_exit();
	594	unregister_filesystem(&cramfs_fs_type);
	595	}
	596
	597	module_init(init_cramfs_fs)
	598	module_exit(exit_cramfs_fs)
	599	MODULE_LICENSE("GPL");