[net-next-2.6.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 two macros may change in future, to provide better st_ino
   semantics. */
#define CRAMINO(x)	(((x)->offset && (x)->size)?(x)->offset<<2:1)
#define OFFSET(x)	((x)->i_ino)

static void setup_inode(struct inode *inode, struct cramfs_inode * cramfs_inode)
{
	static struct timespec zerotime;
	inode->i_mode = cramfs_inode->mode;
	inode->i_uid = cramfs_inode->uid;
	inode->i_size = cramfs_inode->size;
	inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
	inode->i_gid = cramfs_inode->gid;
	/* 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. */
	if (S_ISREG(inode->i_mode)) {
		inode->i_fop = &generic_ro_fops;
		inode->i_data.a_ops = &cramfs_aops;
	} else if (S_ISDIR(inode->i_mode)) {
		inode->i_op = &cramfs_dir_inode_operations;
		inode->i_fop = &cramfs_directory_operations;
	} else if (S_ISLNK(inode->i_mode)) {
		inode->i_op = &page_symlink_inode_operations;
		inode->i_data.a_ops = &cramfs_aops;
	} else {
		init_special_inode(inode, inode->i_mode,
			old_decode_dev(cramfs_inode->size));
	}
}

static struct inode *get_cramfs_inode(struct super_block *sb,
				struct cramfs_inode * cramfs_inode)
{
	struct inode *inode;
	if (CRAMINO(cramfs_inode) == 1) {
		inode = new_inode(sb);
		if (inode) {
			inode->i_ino = 1;
			setup_inode(inode, cramfs_inode);
		}
	} else {
		inode = iget_locked(sb, CRAMINO(cramfs_inode));
		if (inode && (inode->i_state & I_NEW)) {
			setup_inode(inode, cramfs_inode);
			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;
	}
	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);
	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);
		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;

		de = cramfs_read(dir->i_sb, OFFSET(dir) + offset, 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));
			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
	36
	37	/* These two macros may change in future, to provide better st_ino
	38	semantics. */
ff3aea0e	39	#define CRAMINO(x) (((x)->offset && (x)->size)?(x)->offset<<2:1)
1da177e4 LT	40	#define OFFSET(x) ((x)->i_ino)
1da177e4 LT	41
77b8a75f	42	static void setup_inode(struct inode inode, struct cramfs_inode cramfs_inode)
a97c9bf3	43	{
77b8a75f AV	44	static struct timespec zerotime;
	45	inode->i_mode = cramfs_inode->mode;
	46	inode->i_uid = cramfs_inode->uid;
	47	inode->i_size = cramfs_inode->size;
	48	inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
	49	inode->i_gid = cramfs_inode->gid;
	50	/* Struct copy intentional */
	51	inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
	52	/* inode->i_nlink is left 1 - arguably wrong for directories,
	53	but it's the best we can do without reading the directory
	54	contents. 1 yields the right result in GNU find, even
	55	without -noleaf option. */
	56	if (S_ISREG(inode->i_mode)) {
	57	inode->i_fop = &generic_ro_fops;
	58	inode->i_data.a_ops = &cramfs_aops;
	59	} else if (S_ISDIR(inode->i_mode)) {
	60	inode->i_op = &cramfs_dir_inode_operations;
	61	inode->i_fop = &cramfs_directory_operations;
	62	} else if (S_ISLNK(inode->i_mode)) {
	63	inode->i_op = &page_symlink_inode_operations;
	64	inode->i_data.a_ops = &cramfs_aops;
	65	} else {
	66	init_special_inode(inode, inode->i_mode,
	67	old_decode_dev(cramfs_inode->size));
	68	}
a97c9bf3 DJ	69	}
	70
	71	static struct inode get_cramfs_inode(struct super_block sb,
	72	struct cramfs_inode * cramfs_inode)
1da177e4	73	{
77b8a75f AV	74	struct inode *inode;
	75	if (CRAMINO(cramfs_inode) == 1) {
	76	inode = new_inode(sb);
	77	if (inode) {
	78	inode->i_ino = 1;
	79	setup_inode(inode, cramfs_inode);
	80	}
	81	} else {
	82	inode = iget_locked(sb, CRAMINO(cramfs_inode));
b845ff8f	83	if (inode && (inode->i_state & I_NEW)) {
77b8a75f AV	84	setup_inode(inode, cramfs_inode);
77b8a75f AV	85	unlock_new_inode(inode);
82d63fc9	86	}
1da177e4 LT	87	}
	88	return inode;
	89	}
	90
	91	/*
	92	* We have our own block cache: don't fill up the buffer cache
	93	* with the rom-image, because the way the filesystem is set
	94	* up the accesses should be fairly regular and cached in the
	95	* page cache and dentry tree anyway..
	96	*
	97	* This also acts as a way to guarantee contiguous areas of up to
	98	* BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to
	99	* worry about end-of-buffer issues even when decompressing a full
	100	* page cache.
	101	*/
	102	#define READ_BUFFERS (2)
	103	/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
	104	#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
	105
	106	/*
	107	* BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
	108	* data that takes up more space than the original and with unlucky
	109	* alignment.
	110	*/
	111	#define BLKS_PER_BUF_SHIFT (2)
	112	#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
	113	#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE)
	114
	115	static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
	116	static unsigned buffer_blocknr[READ_BUFFERS];
	117	static struct super_block * buffer_dev[READ_BUFFERS];
	118	static int next_buffer;
	119
	120	/*
	121	* Returns a pointer to a buffer containing at least LEN bytes of
	122	* filesystem starting at byte offset OFFSET into the filesystem.
	123	*/
	124	static void cramfs_read(struct super_block sb, unsigned int offset, unsigned int len)
	125	{
	126	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
	127	struct page *pages[BLKS_PER_BUF];
6bbfb077	128	unsigned i, blocknr, buffer;
1da177e4 LT	129	unsigned long devsize;
	130	char *data;
	131
	132	if (!len)
	133	return NULL;
	134	blocknr = offset >> PAGE_CACHE_SHIFT;
	135	offset &= PAGE_CACHE_SIZE - 1;
	136
	137	/* Check if an existing buffer already has the data.. */
	138	for (i = 0; i < READ_BUFFERS; i++) {
	139	unsigned int blk_offset;
	140
	141	if (buffer_dev[i] != sb)
	142	continue;
	143	if (blocknr < buffer_blocknr[i])
	144	continue;
	145	blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
	146	blk_offset += offset;
	147	if (blk_offset + len > BUFFER_SIZE)
	148	continue;
	149	return read_buffers[i] + blk_offset;
	150	}
	151
	152	devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
	153
	154	/* Ok, read in BLKS_PER_BUF pages completely first. */
1da177e4 LT	155	for (i = 0; i < BLKS_PER_BUF; i++) {
	156	struct page *page = NULL;
	157
	158	if (blocknr + i < devsize) {
6fe6900e NP	159	page = read_mapping_page_async(mapping, blocknr + i,
6fe6900e NP	160	NULL);
1da177e4 LT	161	/* synchronous error? */
	162	if (IS_ERR(page))
	163	page = NULL;
	164	}
	165	pages[i] = page;
	166	}
	167
	168	for (i = 0; i < BLKS_PER_BUF; i++) {
	169	struct page *page = pages[i];
	170	if (page) {
	171	wait_on_page_locked(page);
	172	if (!PageUptodate(page)) {
	173	/* asynchronous error */
	174	page_cache_release(page);
	175	pages[i] = NULL;
	176	}
	177	}
	178	}
	179
	180	buffer = next_buffer;
	181	next_buffer = NEXT_BUFFER(buffer);
	182	buffer_blocknr[buffer] = blocknr;
	183	buffer_dev[buffer] = sb;
	184
	185	data = read_buffers[buffer];
	186	for (i = 0; i < BLKS_PER_BUF; i++) {
	187	struct page *page = pages[i];
	188	if (page) {
	189	memcpy(data, kmap(page), PAGE_CACHE_SIZE);
	190	kunmap(page);
	191	page_cache_release(page);
	192	} else
	193	memset(data, 0, PAGE_CACHE_SIZE);
	194	data += PAGE_CACHE_SIZE;
	195	}
	196	return read_buffers[buffer] + offset;
	197	}
	198
	199	static void cramfs_put_super(struct super_block *sb)
	200	{
	201	kfree(sb->s_fs_info);
	202	sb->s_fs_info = NULL;
	203	}
	204
	205	static int cramfs_remount(struct super_block sb, int flags, char *data)
	206	{
	207	*flags \|= MS_RDONLY;
	208	return 0;
	209	}
	210
	211	static int cramfs_fill_super(struct super_block sb, void data, int silent)
	212	{
	213	int i;
	214	struct cramfs_super super;
	215	unsigned long root_offset;
	216	struct cramfs_sb_info *sbi;
	217	struct inode *root;
	218
	219	sb->s_flags \|= MS_RDONLY;
	220
f8314dc6	221	sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
1da177e4 LT	222	if (!sbi)
	223	return -ENOMEM;
	224	sb->s_fs_info = sbi;
1da177e4 LT	225
1da177e4 LT	226	/* Invalidate the read buffers on mount: think disk change.. */
353ab6e9	227	mutex_lock(&read_mutex);
1da177e4 LT	228	for (i = 0; i < READ_BUFFERS; i++)
	229	buffer_blocknr[i] = -1;
	230
	231	/* Read the first block and get the superblock from it */
	232	memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
353ab6e9	233	mutex_unlock(&read_mutex);
1da177e4 LT	234
	235	/* Do sanity checks on the superblock */
	236	if (super.magic != CRAMFS_MAGIC) {
ac8d35c5 AD	237	/* check for wrong endianess */
	238	if (super.magic == CRAMFS_MAGIC_WEND) {
	239	if (!silent)
	240	printk(KERN_ERR "cramfs: wrong endianess\n");
	241	goto out;
	242	}
	243
1da177e4	244	/* check at 512 byte offset */
353ab6e9	245	mutex_lock(&read_mutex);
1da177e4	246	memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
353ab6e9	247	mutex_unlock(&read_mutex);
1da177e4	248	if (super.magic != CRAMFS_MAGIC) {
ac8d35c5 AD	249	if (super.magic == CRAMFS_MAGIC_WEND && !silent)
	250	printk(KERN_ERR "cramfs: wrong endianess\n");
	251	else if (!silent)
1da177e4 LT	252	printk(KERN_ERR "cramfs: wrong magic\n");
	253	goto out;
	254	}
	255	}
	256
	257	/* get feature flags first */
	258	if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
	259	printk(KERN_ERR "cramfs: unsupported filesystem features\n");
	260	goto out;
	261	}
	262
	263	/* Check that the root inode is in a sane state */
	264	if (!S_ISDIR(super.root.mode)) {
	265	printk(KERN_ERR "cramfs: root is not a directory\n");
	266	goto out;
	267	}
	268	root_offset = super.root.offset << 2;
	269	if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
	270	sbi->size=super.size;
	271	sbi->blocks=super.fsid.blocks;
	272	sbi->files=super.fsid.files;
	273	} else {
	274	sbi->size=1<<28;
	275	sbi->blocks=0;
	276	sbi->files=0;
	277	}
	278	sbi->magic=super.magic;
	279	sbi->flags=super.flags;
	280	if (root_offset == 0)
	281	printk(KERN_INFO "cramfs: empty filesystem");
	282	else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
	283	((root_offset != sizeof(struct cramfs_super)) &&
	284	(root_offset != 512 + sizeof(struct cramfs_super))))
	285	{
	286	printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
	287	goto out;
	288	}
	289
	290	/* Set it all up.. */
	291	sb->s_op = &cramfs_ops;
	292	root = get_cramfs_inode(sb, &super.root);
	293	if (!root)
	294	goto out;
	295	sb->s_root = d_alloc_root(root);
	296	if (!sb->s_root) {
	297	iput(root);
	298	goto out;
	299	}
	300	return 0;
	301	out:
	302	kfree(sbi);
	303	sb->s_fs_info = NULL;
	304	return -EINVAL;
	305	}
	306
726c3342	307	static int cramfs_statfs(struct dentry dentry, struct kstatfs buf)
1da177e4	308	{
726c3342	309	struct super_block *sb = dentry->d_sb;
94ea77ac	310	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
726c3342	311
1da177e4 LT	312	buf->f_type = CRAMFS_MAGIC;
	313	buf->f_bsize = PAGE_CACHE_SIZE;
	314	buf->f_blocks = CRAMFS_SB(sb)->blocks;
	315	buf->f_bfree = 0;
	316	buf->f_bavail = 0;
	317	buf->f_files = CRAMFS_SB(sb)->files;
	318	buf->f_ffree = 0;
94ea77ac CL	319	buf->f_fsid.val[0] = (u32)id;
94ea77ac CL	320	buf->f_fsid.val[1] = (u32)(id >> 32);
1da177e4 LT	321	buf->f_namelen = CRAMFS_MAXPATHLEN;
	322	return 0;
	323	}
	324
	325	/*
	326	* Read a cramfs directory entry.
	327	*/
	328	static int cramfs_readdir(struct file filp, void dirent, filldir_t filldir)
	329	{
352d8af7	330	struct inode *inode = filp->f_path.dentry->d_inode;
1da177e4 LT	331	struct super_block *sb = inode->i_sb;
	332	char *buf;
	333	unsigned int offset;
	334	int copied;
	335
	336	/* Offset within the thing. */
	337	offset = filp->f_pos;
	338	if (offset >= inode->i_size)
	339	return 0;
	340	/* Directory entries are always 4-byte aligned */
	341	if (offset & 3)
	342	return -EINVAL;
	343
4176ed59	344	buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
1da177e4 LT	345	if (!buf)
	346	return -ENOMEM;
	347
	348	copied = 0;
	349	while (offset < inode->i_size) {
	350	struct cramfs_inode *de;
	351	unsigned long nextoffset;
	352	char *name;
	353	ino_t ino;
	354	mode_t mode;
	355	int namelen, error;
	356
353ab6e9	357	mutex_lock(&read_mutex);
4176ed59	358	de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
1da177e4 LT	359	name = (char *)(de+1);
	360
	361	/*
	362	* Namelengths on disk are shifted by two
	363	* and the name padded out to 4-byte boundaries
	364	* with zeroes.
	365	*/
	366	namelen = de->namelen << 2;
	367	memcpy(buf, name, namelen);
	368	ino = CRAMINO(de);
	369	mode = de->mode;
353ab6e9	370	mutex_unlock(&read_mutex);
1da177e4 LT	371	nextoffset = offset + sizeof(*de) + namelen;
	372	for (;;) {
	373	if (!namelen) {
	374	kfree(buf);
	375	return -EIO;
	376	}
	377	if (buf[namelen-1])
	378	break;
	379	namelen--;
	380	}
	381	error = filldir(dirent, buf, namelen, offset, ino, mode >> 12);
	382	if (error)
	383	break;
	384
	385	offset = nextoffset;
	386	filp->f_pos = offset;
	387	copied++;
	388	}
	389	kfree(buf);
	390	return 0;
	391	}
	392
	393	/*
	394	* Lookup and fill in the inode data..
	395	*/
	396	static struct dentry * cramfs_lookup(struct inode dir, struct dentry dentry, struct nameidata *nd)
	397	{
	398	unsigned int offset = 0;
	399	int sorted;
	400
353ab6e9	401	mutex_lock(&read_mutex);
1da177e4 LT	402	sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
	403	while (offset < dir->i_size) {
	404	struct cramfs_inode *de;
	405	char *name;
	406	int namelen, retval;
	407
4176ed59	408	de = cramfs_read(dir->i_sb, OFFSET(dir) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
1da177e4 LT	409	name = (char *)(de+1);
	410
	411	/* Try to take advantage of sorted directories */
	412	if (sorted && (dentry->d_name.name[0] < name[0]))
	413	break;
	414
	415	namelen = de->namelen << 2;
	416	offset += sizeof(*de) + namelen;
	417
	418	/* Quick check that the name is roughly the right length */
	419	if (((dentry->d_name.len + 3) & ~3) != namelen)
	420	continue;
	421
	422	for (;;) {
	423	if (!namelen) {
353ab6e9	424	mutex_unlock(&read_mutex);
1da177e4 LT	425	return ERR_PTR(-EIO);
	426	}
	427	if (name[namelen-1])
	428	break;
	429	namelen--;
	430	}
	431	if (namelen != dentry->d_name.len)
	432	continue;
	433	retval = memcmp(dentry->d_name.name, name, namelen);
	434	if (retval > 0)
	435	continue;
	436	if (!retval) {
	437	struct cramfs_inode entry = *de;
353ab6e9	438	mutex_unlock(&read_mutex);
1da177e4 LT	439	d_add(dentry, get_cramfs_inode(dir->i_sb, &entry));
	440	return NULL;
	441	}
	442	/* else (retval < 0) */
	443	if (sorted)
	444	break;
	445	}
353ab6e9	446	mutex_unlock(&read_mutex);
1da177e4 LT	447	d_add(dentry, NULL);
	448	return NULL;
	449	}
	450
	451	static int cramfs_readpage(struct file file, struct page page)
	452	{
	453	struct inode *inode = page->mapping->host;
98310e58 DV	454	u32 maxblock;
98310e58 DV	455	int bytes_filled;
1da177e4 LT	456	void *pgdata;
	457
	458	maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
	459	bytes_filled = 0;
98310e58 DV	460	pgdata = kmap(page);
98310e58 DV	461
1da177e4 LT	462	if (page->index < maxblock) {
	463	struct super_block *sb = inode->i_sb;
	464	u32 blkptr_offset = OFFSET(inode) + page->index*4;
	465	u32 start_offset, compr_len;
	466
	467	start_offset = OFFSET(inode) + maxblock*4;
353ab6e9	468	mutex_lock(&read_mutex);
1da177e4	469	if (page->index)
98310e58 DV	470	start_offset = (u32 ) cramfs_read(sb, blkptr_offset-4,
	471	4);
	472	compr_len = ((u32 ) cramfs_read(sb, blkptr_offset, 4) -
	473	start_offset);
353ab6e9	474	mutex_unlock(&read_mutex);
98310e58	475
1da177e4 LT	476	if (compr_len == 0)
1da177e4 LT	477	; /* hole */
98310e58 DV	478	else if (unlikely(compr_len > (PAGE_CACHE_SIZE << 1))) {
	479	pr_err("cramfs: bad compressed blocksize %u\n",
	480	compr_len);
	481	goto err;
	482	} else {
353ab6e9	483	mutex_lock(&read_mutex);
1da177e4 LT	484	bytes_filled = cramfs_uncompress_block(pgdata,
	485	PAGE_CACHE_SIZE,
	486	cramfs_read(sb, start_offset, compr_len),
	487	compr_len);
353ab6e9	488	mutex_unlock(&read_mutex);
98310e58 DV	489	if (unlikely(bytes_filled < 0))
98310e58 DV	490	goto err;
1da177e4	491	}
98310e58 DV	492	}
98310e58 DV	493
1da177e4	494	memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
1da177e4	495	flush_dcache_page(page);
98310e58	496	kunmap(page);
1da177e4 LT	497	SetPageUptodate(page);
	498	unlock_page(page);
	499	return 0;
98310e58 DV	500
	501	err:
	502	kunmap(page);
	503	ClearPageUptodate(page);
	504	SetPageError(page);
	505	unlock_page(page);
	506	return 0;
1da177e4 LT	507	}
1da177e4 LT	508
f5e54d6e	509	static const struct address_space_operations cramfs_aops = {
1da177e4 LT	510	.readpage = cramfs_readpage
	511	};
	512
	513	/*
	514	* Our operations:
	515	*/
	516
	517	/*
	518	* A directory can only readdir
	519	*/
4b6f5d20	520	static const struct file_operations cramfs_directory_operations = {
1da177e4 LT	521	.llseek = generic_file_llseek,
	522	.read = generic_read_dir,
	523	.readdir = cramfs_readdir,
	524	};
	525
754661f1	526	static const struct inode_operations cramfs_dir_inode_operations = {
1da177e4 LT	527	.lookup = cramfs_lookup,
	528	};
	529
ee9b6d61	530	static const struct super_operations cramfs_ops = {
1da177e4 LT	531	.put_super = cramfs_put_super,
	532	.remount_fs = cramfs_remount,
	533	.statfs = cramfs_statfs,
	534	};
	535
152a0836 AV	536	static struct dentry cramfs_mount(struct file_system_type fs_type,
152a0836 AV	537	int flags, const char dev_name, void data)
1da177e4	538	{
152a0836	539	return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
1da177e4 LT	540	}
	541
	542	static struct file_system_type cramfs_fs_type = {
	543	.owner = THIS_MODULE,
	544	.name = "cramfs",
152a0836	545	.mount = cramfs_mount,
1da177e4 LT	546	.kill_sb = kill_block_super,
	547	.fs_flags = FS_REQUIRES_DEV,
	548	};
	549
	550	static int __init init_cramfs_fs(void)
	551	{
50d44ed0 AD	552	int rv;
	553
	554	rv = cramfs_uncompress_init();
	555	if (rv < 0)
	556	return rv;
	557	rv = register_filesystem(&cramfs_fs_type);
	558	if (rv < 0)
	559	cramfs_uncompress_exit();
	560	return rv;
1da177e4 LT	561	}
	562
	563	static void __exit exit_cramfs_fs(void)
	564	{
	565	cramfs_uncompress_exit();
	566	unregister_filesystem(&cramfs_fs_type);
	567	}
	568
	569	module_init(init_cramfs_fs)
	570	module_exit(exit_cramfs_fs)
	571	MODULE_LICENSE("GPL");