[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 <asm/semaphore.h>

#include <asm/uaccess.h>

static struct super_operations cramfs_ops;
static struct inode_operations cramfs_dir_inode_operations;
static struct file_operations cramfs_directory_operations;
static struct address_space_operations cramfs_aops;

static DECLARE_MUTEX(read_mutex);


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

static struct inode *get_cramfs_inode(struct super_block *sb, struct cramfs_inode * cramfs_inode)
{
	struct inode * inode = new_inode(sb);
	static struct timespec zerotime;

	if (inode) {
		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_blksize = PAGE_CACHE_SIZE;
		inode->i_gid = cramfs_inode->gid;
		/* Struct copy intentional */
		inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
		inode->i_ino = CRAMINO(cramfs_inode);
		/* 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. */
		insert_inode_hash(inode);
		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 {
			inode->i_size = 0;
			inode->i_blocks = 0;
			init_special_inode(inode, inode->i_mode,
				old_decode_dev(cramfs_inode->size));
		}
	}
	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, unread;
	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. */
	unread = 0;
	for (i = 0; i < BLKS_PER_BUF; i++) {
		struct page *page = NULL;

		if (blocknr + i < devsize) {
			page = read_cache_page(mapping, blocknr + i,
				(filler_t *)mapping->a_ops->readpage,
				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 = kmalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
	if (!sbi)
		return -ENOMEM;
	sb->s_fs_info = sbi;
	memset(sbi, 0, sizeof(struct cramfs_sb_info));

	/* Invalidate the read buffers on mount: think disk change.. */
	down(&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));
	up(&read_mutex);

	/* Do sanity checks on the superblock */
	if (super.magic != CRAMFS_MAGIC) {
		/* check at 512 byte offset */
		down(&read_mutex);
		memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
		up(&read_mutex);
		if (super.magic != CRAMFS_MAGIC) {
			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 super_block *sb, struct kstatfs *buf)
{
	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_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_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(256, 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;

		down(&read_mutex);
		de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+256);
		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;
		up(&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;

	down(&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)+256);
		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) {
				up(&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;
			up(&read_mutex);
			d_add(dentry, get_cramfs_inode(dir->i_sb, &entry));
			return NULL;
		}
		/* else (retval < 0) */
		if (sorted)
			break;
	}
	up(&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, bytes_filled;
	void *pgdata;

	maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
	bytes_filled = 0;
	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;
		down(&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);
		up(&read_mutex);
		pgdata = kmap(page);
		if (compr_len == 0)
			; /* hole */
		else {
			down(&read_mutex);
			bytes_filled = cramfs_uncompress_block(pgdata,
				 PAGE_CACHE_SIZE,
				 cramfs_read(sb, start_offset, compr_len),
				 compr_len);
			up(&read_mutex);
		}
	} else
		pgdata = kmap(page);
	memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
	kunmap(page);
	flush_dcache_page(page);
	SetPageUptodate(page);
	unlock_page(page);
	return 0;
}

static struct address_space_operations cramfs_aops = {
	.readpage = cramfs_readpage
};

/*
 * Our operations:
 */

/*
 * A directory can only readdir
 */
static struct file_operations cramfs_directory_operations = {
	.llseek		= generic_file_llseek,
	.read		= generic_read_dir,
	.readdir	= cramfs_readdir,
};

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

static struct super_operations cramfs_ops = {
	.put_super	= cramfs_put_super,
	.remount_fs	= cramfs_remount,
	.statfs		= cramfs_statfs,
};

static struct super_block *cramfs_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data)
{
	return get_sb_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
}

static struct file_system_type cramfs_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "cramfs",
	.get_sb		= cramfs_get_sb,
	.kill_sb	= kill_block_super,
	.fs_flags	= FS_REQUIRES_DEV,
};

static int __init init_cramfs_fs(void)
{
	cramfs_uncompress_init();
	return register_filesystem(&cramfs_fs_type);
}

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