[GitHub/mt8127/android_kernel_alcatel_ttab.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/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(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_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 endianness */
		if (super.magic == CRAMFS_MAGIC_WEND) {
			if (!silent)
				printk(KERN_ERR "cramfs: wrong endianness\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 endianness\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 (IS_ERR(root))
		goto out;
	sb->s_root = d_make_root(root);
	if (!sb->s_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 = file_inode(filp);
	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;
		umode_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, 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("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,
};
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");
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>
1da177e4	23	#include <linux/vfs.h>
353ab6e9	24	#include <linux/mutex.h>
1da177e4 LT	25
	26	#include <asm/uaccess.h>
	27
ee9b6d61	28	static const struct super_operations cramfs_ops;
754661f1	29	static const struct inode_operations cramfs_dir_inode_operations;
4b6f5d20	30	static const struct file_operations cramfs_directory_operations;
f5e54d6e	31	static const struct address_space_operations cramfs_aops;
1da177e4	32
353ab6e9	33	static DEFINE_MUTEX(read_mutex);
1da177e4 LT	34
1da177e4 LT	35
6f772fe6	36	/* These macros may change in future, to provide better st_ino semantics. */
1da177e4 LT	37	#define OFFSET(x) ((x)->i_ino)
1da177e4 LT	38
0577d1ba	39	static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)
a97c9bf3	40	{
6f772fe6 SS	41	if (!cino->offset)
	42	return offset + 1;
	43	if (!cino->size)
	44	return offset + 1;
	45
	46	/*
	47	* The file mode test fixes buggy mkcramfs implementations where
	48	* cramfs_inode->offset is set to a non zero value for entries
	49	* which did not contain data, like devices node and fifos.
	50	*/
	51	switch (cino->mode & S_IFMT) {
	52	case S_IFREG:
	53	case S_IFDIR:
	54	case S_IFLNK:
	55	return cino->offset << 2;
	56	default:
	57	break;
	58	}
	59	return offset + 1;
	60	}
	61
	62	static struct inode get_cramfs_inode(struct super_block sb,
0577d1ba	63	const struct cramfs_inode *cramfs_inode, unsigned int offset)
6f772fe6 SS	64	{
6f772fe6 SS	65	struct inode *inode;
77b8a75f	66	static struct timespec zerotime;
6f772fe6 SS	67
	68	inode = iget_locked(sb, cramino(cramfs_inode, offset));
	69	if (!inode)
	70	return ERR_PTR(-ENOMEM);
	71	if (!(inode->i_state & I_NEW))
	72	return inode;
	73
	74	switch (cramfs_inode->mode & S_IFMT) {
	75	case S_IFREG:
	76	inode->i_fop = &generic_ro_fops;
	77	inode->i_data.a_ops = &cramfs_aops;
	78	break;
	79	case S_IFDIR:
	80	inode->i_op = &cramfs_dir_inode_operations;
	81	inode->i_fop = &cramfs_directory_operations;
	82	break;
	83	case S_IFLNK:
	84	inode->i_op = &page_symlink_inode_operations;
	85	inode->i_data.a_ops = &cramfs_aops;
	86	break;
	87	default:
	88	init_special_inode(inode, cramfs_inode->mode,
	89	old_decode_dev(cramfs_inode->size));
	90	}
	91
77b8a75f	92	inode->i_mode = cramfs_inode->mode;
a7d9cfe9 EB	93	i_uid_write(inode, cramfs_inode->uid);
a7d9cfe9 EB	94	i_gid_write(inode, cramfs_inode->gid);
6f772fe6 SS	95
	96	/* if the lower 2 bits are zero, the inode contains data */
	97	if (!(inode->i_ino & 3)) {
	98	inode->i_size = cramfs_inode->size;
	99	inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
	100	}
	101
77b8a75f AV	102	/* Struct copy intentional */
	103	inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
	104	/* inode->i_nlink is left 1 - arguably wrong for directories,
	105	but it's the best we can do without reading the directory
	106	contents. 1 yields the right result in GNU find, even
	107	without -noleaf option. */
a97c9bf3	108
6f772fe6 SS	109	unlock_new_inode(inode);
6f772fe6 SS	110
1da177e4 LT	111	return inode;
	112	}
	113
	114	/*
	115	* We have our own block cache: don't fill up the buffer cache
	116	* with the rom-image, because the way the filesystem is set
	117	* up the accesses should be fairly regular and cached in the
	118	* page cache and dentry tree anyway..
	119	*
	120	* This also acts as a way to guarantee contiguous areas of up to
	121	* BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to
	122	* worry about end-of-buffer issues even when decompressing a full
	123	* page cache.
	124	*/
	125	#define READ_BUFFERS (2)
	126	/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
	127	#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
	128
	129	/*
	130	* BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
	131	* data that takes up more space than the original and with unlucky
	132	* alignment.
	133	*/
	134	#define BLKS_PER_BUF_SHIFT (2)
	135	#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
	136	#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE)
	137
	138	static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
	139	static unsigned buffer_blocknr[READ_BUFFERS];
	140	static struct super_block * buffer_dev[READ_BUFFERS];
	141	static int next_buffer;
	142
	143	/*
	144	* Returns a pointer to a buffer containing at least LEN bytes of
	145	* filesystem starting at byte offset OFFSET into the filesystem.
	146	*/
	147	static void cramfs_read(struct super_block sb, unsigned int offset, unsigned int len)
	148	{
	149	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
	150	struct page *pages[BLKS_PER_BUF];
6bbfb077	151	unsigned i, blocknr, buffer;
1da177e4 LT	152	unsigned long devsize;
	153	char *data;
	154
	155	if (!len)
	156	return NULL;
	157	blocknr = offset >> PAGE_CACHE_SHIFT;
	158	offset &= PAGE_CACHE_SIZE - 1;
	159
	160	/* Check if an existing buffer already has the data.. */
	161	for (i = 0; i < READ_BUFFERS; i++) {
	162	unsigned int blk_offset;
	163
	164	if (buffer_dev[i] != sb)
	165	continue;
	166	if (blocknr < buffer_blocknr[i])
	167	continue;
	168	blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
	169	blk_offset += offset;
	170	if (blk_offset + len > BUFFER_SIZE)
	171	continue;
	172	return read_buffers[i] + blk_offset;
	173	}
	174
	175	devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
	176
	177	/* Ok, read in BLKS_PER_BUF pages completely first. */
1da177e4 LT	178	for (i = 0; i < BLKS_PER_BUF; i++) {
	179	struct page *page = NULL;
	180
	181	if (blocknr + i < devsize) {
6fe6900e NP	182	page = read_mapping_page_async(mapping, blocknr + i,
6fe6900e NP	183	NULL);
1da177e4 LT	184	/* synchronous error? */
	185	if (IS_ERR(page))
	186	page = NULL;
	187	}
	188	pages[i] = page;
	189	}
	190
	191	for (i = 0; i < BLKS_PER_BUF; i++) {
	192	struct page *page = pages[i];
	193	if (page) {
	194	wait_on_page_locked(page);
	195	if (!PageUptodate(page)) {
	196	/* asynchronous error */
	197	page_cache_release(page);
	198	pages[i] = NULL;
	199	}
	200	}
	201	}
	202
	203	buffer = next_buffer;
	204	next_buffer = NEXT_BUFFER(buffer);
	205	buffer_blocknr[buffer] = blocknr;
	206	buffer_dev[buffer] = sb;
	207
	208	data = read_buffers[buffer];
	209	for (i = 0; i < BLKS_PER_BUF; i++) {
	210	struct page *page = pages[i];
	211	if (page) {
	212	memcpy(data, kmap(page), PAGE_CACHE_SIZE);
	213	kunmap(page);
	214	page_cache_release(page);
	215	} else
	216	memset(data, 0, PAGE_CACHE_SIZE);
	217	data += PAGE_CACHE_SIZE;
	218	}
	219	return read_buffers[buffer] + offset;
	220	}
	221
	222	static void cramfs_put_super(struct super_block *sb)
	223	{
	224	kfree(sb->s_fs_info);
	225	sb->s_fs_info = NULL;
	226	}
	227
	228	static int cramfs_remount(struct super_block sb, int flags, char *data)
	229	{
	230	*flags \|= MS_RDONLY;
	231	return 0;
	232	}
	233
	234	static int cramfs_fill_super(struct super_block sb, void data, int silent)
	235	{
	236	int i;
	237	struct cramfs_super super;
	238	unsigned long root_offset;
	239	struct cramfs_sb_info *sbi;
	240	struct inode *root;
	241
	242	sb->s_flags \|= MS_RDONLY;
	243
f8314dc6	244	sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
1da177e4 LT	245	if (!sbi)
	246	return -ENOMEM;
	247	sb->s_fs_info = sbi;
1da177e4 LT	248
1da177e4 LT	249	/* Invalidate the read buffers on mount: think disk change.. */
353ab6e9	250	mutex_lock(&read_mutex);
1da177e4 LT	251	for (i = 0; i < READ_BUFFERS; i++)
	252	buffer_blocknr[i] = -1;
	253
	254	/* Read the first block and get the superblock from it */
	255	memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
353ab6e9	256	mutex_unlock(&read_mutex);
1da177e4 LT	257
	258	/* Do sanity checks on the superblock */
	259	if (super.magic != CRAMFS_MAGIC) {
0cc785ec	260	/* check for wrong endianness */
ac8d35c5 AD	261	if (super.magic == CRAMFS_MAGIC_WEND) {
ac8d35c5 AD	262	if (!silent)
0cc785ec	263	printk(KERN_ERR "cramfs: wrong endianness\n");
ac8d35c5 AD	264	goto out;
	265	}
	266
1da177e4	267	/* check at 512 byte offset */
353ab6e9	268	mutex_lock(&read_mutex);
1da177e4	269	memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
353ab6e9	270	mutex_unlock(&read_mutex);
1da177e4	271	if (super.magic != CRAMFS_MAGIC) {
ac8d35c5	272	if (super.magic == CRAMFS_MAGIC_WEND && !silent)
0cc785ec	273	printk(KERN_ERR "cramfs: wrong endianness\n");
ac8d35c5	274	else if (!silent)
1da177e4 LT	275	printk(KERN_ERR "cramfs: wrong magic\n");
	276	goto out;
	277	}
	278	}
	279
	280	/* get feature flags first */
	281	if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
	282	printk(KERN_ERR "cramfs: unsupported filesystem features\n");
	283	goto out;
	284	}
	285
	286	/* Check that the root inode is in a sane state */
	287	if (!S_ISDIR(super.root.mode)) {
	288	printk(KERN_ERR "cramfs: root is not a directory\n");
	289	goto out;
	290	}
6f772fe6 SS	291	/* correct strange, hard-coded permissions of mkcramfs */
	292	super.root.mode \|= (S_IRUSR \| S_IXUSR \| S_IRGRP \| S_IXGRP \| S_IROTH \| S_IXOTH);
	293
1da177e4 LT	294	root_offset = super.root.offset << 2;
	295	if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
	296	sbi->size=super.size;
	297	sbi->blocks=super.fsid.blocks;
	298	sbi->files=super.fsid.files;
	299	} else {
	300	sbi->size=1<<28;
	301	sbi->blocks=0;
	302	sbi->files=0;
	303	}
	304	sbi->magic=super.magic;
	305	sbi->flags=super.flags;
	306	if (root_offset == 0)
	307	printk(KERN_INFO "cramfs: empty filesystem");
	308	else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
	309	((root_offset != sizeof(struct cramfs_super)) &&
	310	(root_offset != 512 + sizeof(struct cramfs_super))))
	311	{
	312	printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
	313	goto out;
	314	}
	315
	316	/* Set it all up.. */
	317	sb->s_op = &cramfs_ops;
6f772fe6	318	root = get_cramfs_inode(sb, &super.root, 0);
0577d1ba	319	if (IS_ERR(root))
1da177e4	320	goto out;
48fde701 AV	321	sb->s_root = d_make_root(root);
48fde701 AV	322	if (!sb->s_root)
1da177e4	323	goto out;
1da177e4 LT	324	return 0;
	325	out:
	326	kfree(sbi);
	327	sb->s_fs_info = NULL;
	328	return -EINVAL;
	329	}
	330
726c3342	331	static int cramfs_statfs(struct dentry dentry, struct kstatfs buf)
1da177e4	332	{
726c3342	333	struct super_block *sb = dentry->d_sb;
94ea77ac	334	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
726c3342	335
1da177e4 LT	336	buf->f_type = CRAMFS_MAGIC;
	337	buf->f_bsize = PAGE_CACHE_SIZE;
	338	buf->f_blocks = CRAMFS_SB(sb)->blocks;
	339	buf->f_bfree = 0;
	340	buf->f_bavail = 0;
	341	buf->f_files = CRAMFS_SB(sb)->files;
	342	buf->f_ffree = 0;
94ea77ac CL	343	buf->f_fsid.val[0] = (u32)id;
94ea77ac CL	344	buf->f_fsid.val[1] = (u32)(id >> 32);
1da177e4 LT	345	buf->f_namelen = CRAMFS_MAXPATHLEN;
	346	return 0;
	347	}
	348
	349	/*
	350	* Read a cramfs directory entry.
	351	*/
	352	static int cramfs_readdir(struct file filp, void dirent, filldir_t filldir)
	353	{
496ad9aa	354	struct inode *inode = file_inode(filp);
1da177e4 LT	355	struct super_block *sb = inode->i_sb;
	356	char *buf;
	357	unsigned int offset;
	358	int copied;
	359
	360	/* Offset within the thing. */
	361	offset = filp->f_pos;
	362	if (offset >= inode->i_size)
	363	return 0;
	364	/* Directory entries are always 4-byte aligned */
	365	if (offset & 3)
	366	return -EINVAL;
	367
4176ed59	368	buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
1da177e4 LT	369	if (!buf)
	370	return -ENOMEM;
	371
	372	copied = 0;
	373	while (offset < inode->i_size) {
	374	struct cramfs_inode *de;
	375	unsigned long nextoffset;
	376	char *name;
	377	ino_t ino;
175a4eb7	378	umode_t mode;
1da177e4 LT	379	int namelen, error;
1da177e4 LT	380
353ab6e9	381	mutex_lock(&read_mutex);
4176ed59	382	de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
1da177e4 LT	383	name = (char *)(de+1);
	384
	385	/*
	386	* Namelengths on disk are shifted by two
	387	* and the name padded out to 4-byte boundaries
	388	* with zeroes.
	389	*/
	390	namelen = de->namelen << 2;
	391	memcpy(buf, name, namelen);
6f772fe6	392	ino = cramino(de, OFFSET(inode) + offset);
1da177e4	393	mode = de->mode;
353ab6e9	394	mutex_unlock(&read_mutex);
1da177e4 LT	395	nextoffset = offset + sizeof(*de) + namelen;
	396	for (;;) {
	397	if (!namelen) {
	398	kfree(buf);
	399	return -EIO;
	400	}
	401	if (buf[namelen-1])
	402	break;
	403	namelen--;
	404	}
	405	error = filldir(dirent, buf, namelen, offset, ino, mode >> 12);
	406	if (error)
	407	break;
	408
	409	offset = nextoffset;
	410	filp->f_pos = offset;
	411	copied++;
	412	}
	413	kfree(buf);
	414	return 0;
	415	}
	416
	417	/*
	418	* Lookup and fill in the inode data..
	419	*/
00cd8dd3	420	static struct dentry * cramfs_lookup(struct inode dir, struct dentry dentry, unsigned int flags)
1da177e4 LT	421	{
1da177e4 LT	422	unsigned int offset = 0;
0577d1ba	423	struct inode *inode = NULL;
1da177e4 LT	424	int sorted;
1da177e4 LT	425
353ab6e9	426	mutex_lock(&read_mutex);
1da177e4 LT	427	sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
	428	while (offset < dir->i_size) {
	429	struct cramfs_inode *de;
	430	char *name;
	431	int namelen, retval;
6f772fe6	432	int dir_off = OFFSET(dir) + offset;
1da177e4	433
6f772fe6	434	de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
1da177e4 LT	435	name = (char *)(de+1);
	436
	437	/* Try to take advantage of sorted directories */
	438	if (sorted && (dentry->d_name.name[0] < name[0]))
	439	break;
	440
	441	namelen = de->namelen << 2;
	442	offset += sizeof(*de) + namelen;
	443
	444	/* Quick check that the name is roughly the right length */
	445	if (((dentry->d_name.len + 3) & ~3) != namelen)
	446	continue;
	447
	448	for (;;) {
	449	if (!namelen) {
0577d1ba AV	450	inode = ERR_PTR(-EIO);
0577d1ba AV	451	goto out;
1da177e4 LT	452	}
	453	if (name[namelen-1])
	454	break;
	455	namelen--;
	456	}
	457	if (namelen != dentry->d_name.len)
	458	continue;
	459	retval = memcmp(dentry->d_name.name, name, namelen);
	460	if (retval > 0)
	461	continue;
	462	if (!retval) {
0577d1ba AV	463	inode = get_cramfs_inode(dir->i_sb, de, dir_off);
0577d1ba AV	464	break;
1da177e4 LT	465	}
	466	/* else (retval < 0) */
	467	if (sorted)
	468	break;
	469	}
0577d1ba	470	out:
353ab6e9	471	mutex_unlock(&read_mutex);
0577d1ba AV	472	if (IS_ERR(inode))
	473	return ERR_CAST(inode);
	474	d_add(dentry, inode);
1da177e4 LT	475	return NULL;
	476	}
	477
	478	static int cramfs_readpage(struct file file, struct page page)
	479	{
	480	struct inode *inode = page->mapping->host;
98310e58 DV	481	u32 maxblock;
98310e58 DV	482	int bytes_filled;
1da177e4 LT	483	void *pgdata;
	484
	485	maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
	486	bytes_filled = 0;
98310e58 DV	487	pgdata = kmap(page);
98310e58 DV	488
1da177e4 LT	489	if (page->index < maxblock) {
	490	struct super_block *sb = inode->i_sb;
	491	u32 blkptr_offset = OFFSET(inode) + page->index*4;
	492	u32 start_offset, compr_len;
	493
	494	start_offset = OFFSET(inode) + maxblock*4;
353ab6e9	495	mutex_lock(&read_mutex);
1da177e4	496	if (page->index)
98310e58 DV	497	start_offset = (u32 ) cramfs_read(sb, blkptr_offset-4,
	498	4);
	499	compr_len = ((u32 ) cramfs_read(sb, blkptr_offset, 4) -
	500	start_offset);
353ab6e9	501	mutex_unlock(&read_mutex);
98310e58	502
1da177e4 LT	503	if (compr_len == 0)
1da177e4 LT	504	; /* hole */
98310e58 DV	505	else if (unlikely(compr_len > (PAGE_CACHE_SIZE << 1))) {
	506	pr_err("cramfs: bad compressed blocksize %u\n",
	507	compr_len);
	508	goto err;
	509	} else {
353ab6e9	510	mutex_lock(&read_mutex);
1da177e4 LT	511	bytes_filled = cramfs_uncompress_block(pgdata,
	512	PAGE_CACHE_SIZE,
	513	cramfs_read(sb, start_offset, compr_len),
	514	compr_len);
353ab6e9	515	mutex_unlock(&read_mutex);
98310e58 DV	516	if (unlikely(bytes_filled < 0))
98310e58 DV	517	goto err;
1da177e4	518	}
98310e58 DV	519	}
98310e58 DV	520
1da177e4	521	memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
1da177e4	522	flush_dcache_page(page);
98310e58	523	kunmap(page);
1da177e4 LT	524	SetPageUptodate(page);
	525	unlock_page(page);
	526	return 0;
98310e58 DV	527
	528	err:
	529	kunmap(page);
	530	ClearPageUptodate(page);
	531	SetPageError(page);
	532	unlock_page(page);
	533	return 0;
1da177e4 LT	534	}
1da177e4 LT	535
f5e54d6e	536	static const struct address_space_operations cramfs_aops = {
1da177e4 LT	537	.readpage = cramfs_readpage
	538	};
	539
	540	/*
	541	* Our operations:
	542	*/
	543
	544	/*
	545	* A directory can only readdir
	546	*/
4b6f5d20	547	static const struct file_operations cramfs_directory_operations = {
1da177e4 LT	548	.llseek = generic_file_llseek,
	549	.read = generic_read_dir,
	550	.readdir = cramfs_readdir,
	551	};
	552
754661f1	553	static const struct inode_operations cramfs_dir_inode_operations = {
1da177e4 LT	554	.lookup = cramfs_lookup,
	555	};
	556
ee9b6d61	557	static const struct super_operations cramfs_ops = {
1da177e4 LT	558	.put_super = cramfs_put_super,
	559	.remount_fs = cramfs_remount,
	560	.statfs = cramfs_statfs,
	561	};
	562
152a0836 AV	563	static struct dentry cramfs_mount(struct file_system_type fs_type,
152a0836 AV	564	int flags, const char dev_name, void data)
1da177e4	565	{
152a0836	566	return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
1da177e4 LT	567	}
	568
	569	static struct file_system_type cramfs_fs_type = {
	570	.owner = THIS_MODULE,
	571	.name = "cramfs",
152a0836	572	.mount = cramfs_mount,
1da177e4 LT	573	.kill_sb = kill_block_super,
	574	.fs_flags = FS_REQUIRES_DEV,
	575	};
7f78e035	576	MODULE_ALIAS_FS("cramfs");
1da177e4 LT	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");