[linux-2.6-block.git] / fs / romfs / super.c

/* Block- or MTD-based romfs
 *
 * Copyright © 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * Derived from: ROMFS file system, Linux implementation
 *
 * Copyright © 1997-1999  Janos Farkas <chexum@shadow.banki.hu>
 *
 * Using parts of the minix filesystem
 * Copyright © 1991, 1992  Linus Torvalds
 *
 * and parts of the affs filesystem additionally
 * Copyright © 1993  Ray Burr
 * Copyright © 1996  Hans-Joachim Widmaier
 *
 * Changes
 *					Changed for 2.1.19 modules
 *	Jan 1997			Initial release
 *	Jun 1997			2.1.43+ changes
 *					Proper page locking in readpage
 *					Changed to work with 2.1.45+ fs
 *	Jul 1997			Fixed follow_link
 *			2.1.47
 *					lookup shouldn't return -ENOENT
 *					from Horst von Brand:
 *					  fail on wrong checksum
 *					  double unlock_super was possible
 *					  correct namelen for statfs
 *					spotted by Bill Hawes:
 *					  readlink shouldn't iput()
 *	Jun 1998	2.1.106		from Avery Pennarun: glibc scandir()
 *					  exposed a problem in readdir
 *			2.1.107		code-freeze spellchecker run
 *	Aug 1998			2.1.118+ VFS changes
 *	Sep 1998	2.1.122		another VFS change (follow_link)
 *	Apr 1999	2.2.7		no more EBADF checking in
 *					  lookup/readdir, use ERR_PTR
 *	Jun 1999	2.3.6		d_alloc_root use changed
 *			2.3.9		clean up usage of ENOENT/negative
 *					  dentries in lookup
 *					clean up page flags setting
 *					  (error, uptodate, locking) in
 *					  in readpage
 *					use init_special_inode for
 *					  fifos/sockets (and streamline) in
 *					  read_inode, fix _ops table order
 *	Aug 1999	2.3.16		__initfunc() => __init change
 *	Oct 1999	2.3.24		page->owner hack obsoleted
 *	Nov 1999	2.3.27		2.3.25+ page->offset => index change
 *
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/parser.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/statfs.h>
#include <linux/mtd/super.h>
#include <linux/ctype.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/uaccess.h>
#include "internal.h"

static struct kmem_cache *romfs_inode_cachep;

static const umode_t romfs_modemap[8] = {
	0,			/* hard link */
	S_IFDIR  | 0644,	/* directory */
	S_IFREG  | 0644,	/* regular file */
	S_IFLNK  | 0777,	/* symlink */
	S_IFBLK  | 0600,	/* blockdev */
	S_IFCHR  | 0600,	/* chardev */
	S_IFSOCK | 0644,	/* socket */
	S_IFIFO  | 0644		/* FIFO */
};

static const unsigned char romfs_dtype_table[] = {
	DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
};

static struct inode *romfs_iget(struct super_block *sb, unsigned long pos);

/*
 * read a page worth of data from the image
 */
static int romfs_readpage(struct file *file, struct page *page)
{
	struct inode *inode = page->mapping->host;
	loff_t offset, size;
	unsigned long fillsize, pos;
	void *buf;
	int ret;

	buf = kmap(page);
	if (!buf)
		return -ENOMEM;

	/* 32 bit warning -- but not for us :) */
	offset = page_offset(page);
	size = i_size_read(inode);
	fillsize = 0;
	ret = 0;
	if (offset < size) {
		size -= offset;
		fillsize = size > PAGE_SIZE ? PAGE_SIZE : size;

		pos = ROMFS_I(inode)->i_dataoffset + offset;

		ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize);
		if (ret < 0) {
			SetPageError(page);
			fillsize = 0;
			ret = -EIO;
		}
	}

	if (fillsize < PAGE_SIZE)
		memset(buf + fillsize, 0, PAGE_SIZE - fillsize);
	if (ret == 0)
		SetPageUptodate(page);

	flush_dcache_page(page);
	kunmap(page);
	unlock_page(page);
	return ret;
}

static const struct address_space_operations romfs_aops = {
	.readpage	= romfs_readpage
};

/*
 * read the entries from a directory
 */
static int romfs_readdir(struct file *file, struct dir_context *ctx)
{
	struct inode *i = file_inode(file);
	struct romfs_inode ri;
	unsigned long offset, maxoff;
	int j, ino, nextfh;
	char fsname[ROMFS_MAXFN];	/* XXX dynamic? */
	int ret;

	maxoff = romfs_maxsize(i->i_sb);

	offset = ctx->pos;
	if (!offset) {
		offset = i->i_ino & ROMFH_MASK;
		ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
		if (ret < 0)
			goto out;
		offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	}

	/* Not really failsafe, but we are read-only... */
	for (;;) {
		if (!offset || offset >= maxoff) {
			offset = maxoff;
			ctx->pos = offset;
			goto out;
		}
		ctx->pos = offset;

		/* Fetch inode info */
		ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
		if (ret < 0)
			goto out;

		j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE,
				      sizeof(fsname) - 1);
		if (j < 0)
			goto out;

		ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j);
		if (ret < 0)
			goto out;
		fsname[j] = '\0';

		ino = offset;
		nextfh = be32_to_cpu(ri.next);
		if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
			ino = be32_to_cpu(ri.spec);
		if (!dir_emit(ctx, fsname, j, ino,
			    romfs_dtype_table[nextfh & ROMFH_TYPE]))
			goto out;

		offset = nextfh & ROMFH_MASK;
	}
out:
	return 0;
}

/*
 * look up an entry in a directory
 */
static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry,
				   unsigned int flags)
{
	unsigned long offset, maxoff;
	struct inode *inode;
	struct romfs_inode ri;
	const char *name;		/* got from dentry */
	int len, ret;

	offset = dir->i_ino & ROMFH_MASK;
	ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE);
	if (ret < 0)
		goto error;

	/* search all the file entries in the list starting from the one
	 * pointed to by the directory's special data */
	maxoff = romfs_maxsize(dir->i_sb);
	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;

	name = dentry->d_name.name;
	len = dentry->d_name.len;

	for (;;) {
		if (!offset || offset >= maxoff)
			goto out0;

		ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri));
		if (ret < 0)
			goto error;

		/* try to match the first 16 bytes of name */
		ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,
				       len);
		if (ret < 0)
			goto error;
		if (ret == 1)
			break;

		/* next entry */
		offset = be32_to_cpu(ri.next) & ROMFH_MASK;
	}

	/* Hard link handling */
	if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
		offset = be32_to_cpu(ri.spec) & ROMFH_MASK;

	inode = romfs_iget(dir->i_sb, offset);
	if (IS_ERR(inode)) {
		ret = PTR_ERR(inode);
		goto error;
	}
	goto outi;

	/*
	 * it's a bit funky, _lookup needs to return an error code
	 * (negative) or a NULL, both as a dentry.  ENOENT should not
	 * be returned, instead we need to create a negative dentry by
	 * d_add(dentry, NULL); and return 0 as no error.
	 * (Although as I see, it only matters on writable file
	 * systems).
	 */
out0:
	inode = NULL;
outi:
	d_add(dentry, inode);
	ret = 0;
error:
	return ERR_PTR(ret);
}

static const struct file_operations romfs_dir_operations = {
	.read		= generic_read_dir,
	.iterate_shared	= romfs_readdir,
	.llseek		= generic_file_llseek,
};

static const struct inode_operations romfs_dir_inode_operations = {
	.lookup		= romfs_lookup,
};

/*
 * get a romfs inode based on its position in the image (which doubles as the
 * inode number)
 */
static struct inode *romfs_iget(struct super_block *sb, unsigned long pos)
{
	struct romfs_inode_info *inode;
	struct romfs_inode ri;
	struct inode *i;
	unsigned long nlen;
	unsigned nextfh;
	int ret;
	umode_t mode;

	/* we might have to traverse a chain of "hard link" file entries to get
	 * to the actual file */
	for (;;) {
		ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));
		if (ret < 0)
			goto error;

		/* XXX: do romfs_checksum here too (with name) */

		nextfh = be32_to_cpu(ri.next);
		if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
			break;

		pos = be32_to_cpu(ri.spec) & ROMFH_MASK;
	}

	/* determine the length of the filename */
	nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);
	if (IS_ERR_VALUE(nlen))
		goto eio;

	/* get an inode for this image position */
	i = iget_locked(sb, pos);
	if (!i)
		return ERR_PTR(-ENOMEM);

	if (!(i->i_state & I_NEW))
		return i;

	/* precalculate the data offset */
	inode = ROMFS_I(i);
	inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;
	inode->i_dataoffset = pos + inode->i_metasize;

	set_nlink(i, 1);		/* Hard to decide.. */
	i->i_size = be32_to_cpu(ri.size);
	i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
	i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0;

	/* set up mode and ops */
	mode = romfs_modemap[nextfh & ROMFH_TYPE];

	switch (nextfh & ROMFH_TYPE) {
	case ROMFH_DIR:
		i->i_size = ROMFS_I(i)->i_metasize;
		i->i_op = &romfs_dir_inode_operations;
		i->i_fop = &romfs_dir_operations;
		if (nextfh & ROMFH_EXEC)
			mode |= S_IXUGO;
		break;
	case ROMFH_REG:
		i->i_fop = &romfs_ro_fops;
		i->i_data.a_ops = &romfs_aops;
		if (nextfh & ROMFH_EXEC)
			mode |= S_IXUGO;
		break;
	case ROMFH_SYM:
		i->i_op = &page_symlink_inode_operations;
		inode_nohighmem(i);
		i->i_data.a_ops = &romfs_aops;
		mode |= S_IRWXUGO;
		break;
	default:
		/* depending on MBZ for sock/fifos */
		nextfh = be32_to_cpu(ri.spec);
		init_special_inode(i, mode, MKDEV(nextfh >> 16,
						  nextfh & 0xffff));
		break;
	}

	i->i_mode = mode;

	unlock_new_inode(i);
	return i;

eio:
	ret = -EIO;
error:
	pr_err("read error for inode 0x%lx\n", pos);
	return ERR_PTR(ret);
}

/*
 * allocate a new inode
 */
static struct inode *romfs_alloc_inode(struct super_block *sb)
{
	struct romfs_inode_info *inode;

	inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL);
	return inode ? &inode->vfs_inode : NULL;
}

/*
 * return a spent inode to the slab cache
 */
static void romfs_i_callback(struct rcu_head *head)
{
	struct inode *inode = container_of(head, struct inode, i_rcu);

	kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
}

static void romfs_destroy_inode(struct inode *inode)
{
	call_rcu(&inode->i_rcu, romfs_i_callback);
}

/*
 * get filesystem statistics
 */
static int romfs_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 = ROMFS_MAGIC;
	buf->f_namelen = ROMFS_MAXFN;
	buf->f_bsize = ROMBSIZE;
	buf->f_bfree = buf->f_bavail = buf->f_ffree;
	buf->f_blocks =
		(romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;
	buf->f_fsid.val[0] = (u32)id;
	buf->f_fsid.val[1] = (u32)(id >> 32);
	return 0;
}

/*
 * remounting must involve read-only
 */
static int romfs_remount(struct super_block *sb, int *flags, char *data)
{
	sync_filesystem(sb);
	*flags |= MS_RDONLY;
	return 0;
}

static const struct super_operations romfs_super_ops = {
	.alloc_inode	= romfs_alloc_inode,
	.destroy_inode	= romfs_destroy_inode,
	.statfs		= romfs_statfs,
	.remount_fs	= romfs_remount,
};

/*
 * checksum check on part of a romfs filesystem
 */
static __u32 romfs_checksum(const void *data, int size)
{
	const __be32 *ptr = data;
	__u32 sum;

	sum = 0;
	size >>= 2;
	while (size > 0) {
		sum += be32_to_cpu(*ptr++);
		size--;
	}
	return sum;
}

/*
 * fill in the superblock
 */
static int romfs_fill_super(struct super_block *sb, void *data, int silent)
{
	struct romfs_super_block *rsb;
	struct inode *root;
	unsigned long pos, img_size;
	const char *storage;
	size_t len;
	int ret;

#ifdef CONFIG_BLOCK
	if (!sb->s_mtd) {
		sb_set_blocksize(sb, ROMBSIZE);
	} else {
		sb->s_blocksize = ROMBSIZE;
		sb->s_blocksize_bits = blksize_bits(ROMBSIZE);
	}
#endif

	sb->s_maxbytes = 0xFFFFFFFF;
	sb->s_magic = ROMFS_MAGIC;
	sb->s_flags |= MS_RDONLY | MS_NOATIME;
	sb->s_op = &romfs_super_ops;

	/* read the image superblock and check it */
	rsb = kmalloc(512, GFP_KERNEL);
	if (!rsb)
		return -ENOMEM;

	sb->s_fs_info = (void *) 512;
	ret = romfs_dev_read(sb, 0, rsb, 512);
	if (ret < 0)
		goto error_rsb;

	img_size = be32_to_cpu(rsb->size);

	if (sb->s_mtd && img_size > sb->s_mtd->size)
		goto error_rsb_inval;

	sb->s_fs_info = (void *) img_size;

	if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 ||
	    img_size < ROMFH_SIZE) {
		if (!silent)
			pr_warn("VFS: Can't find a romfs filesystem on dev %s.\n",
			       sb->s_id);
		goto error_rsb_inval;
	}

	if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
		pr_err("bad initial checksum on dev %s.\n", sb->s_id);
		goto error_rsb_inval;
	}

	storage = sb->s_mtd ? "MTD" : "the block layer";

	len = strnlen(rsb->name, ROMFS_MAXFN);
	if (!silent)
		pr_notice("Mounting image '%*.*s' through %s\n",
			  (unsigned) len, (unsigned) len, rsb->name, storage);

	kfree(rsb);
	rsb = NULL;

	/* find the root directory */
	pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;

	root = romfs_iget(sb, pos);
	if (IS_ERR(root))
		return PTR_ERR(root);

	sb->s_root = d_make_root(root);
	if (!sb->s_root)
		return -ENOMEM;

	return 0;

error_rsb_inval:
	ret = -EINVAL;
error_rsb:
	kfree(rsb);
	return ret;
}

/*
 * get a superblock for mounting
 */
static struct dentry *romfs_mount(struct file_system_type *fs_type,
			int flags, const char *dev_name,
			void *data)
{
	struct dentry *ret = ERR_PTR(-EINVAL);

#ifdef CONFIG_ROMFS_ON_MTD
	ret = mount_mtd(fs_type, flags, dev_name, data, romfs_fill_super);
#endif
#ifdef CONFIG_ROMFS_ON_BLOCK
	if (ret == ERR_PTR(-EINVAL))
		ret = mount_bdev(fs_type, flags, dev_name, data,
				  romfs_fill_super);
#endif
	return ret;
}

/*
 * destroy a romfs superblock in the appropriate manner
 */
static void romfs_kill_sb(struct super_block *sb)
{
#ifdef CONFIG_ROMFS_ON_MTD
	if (sb->s_mtd) {
		kill_mtd_super(sb);
		return;
	}
#endif
#ifdef CONFIG_ROMFS_ON_BLOCK
	if (sb->s_bdev) {
		kill_block_super(sb);
		return;
	}
#endif
}

static struct file_system_type romfs_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "romfs",
	.mount		= romfs_mount,
	.kill_sb	= romfs_kill_sb,
	.fs_flags	= FS_REQUIRES_DEV,
};
MODULE_ALIAS_FS("romfs");

/*
 * inode storage initialiser
 */
static void romfs_i_init_once(void *_inode)
{
	struct romfs_inode_info *inode = _inode;

	inode_init_once(&inode->vfs_inode);
}

/*
 * romfs module initialisation
 */
static int __init init_romfs_fs(void)
{
	int ret;

	pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n");

	romfs_inode_cachep =
		kmem_cache_create("romfs_i",
				  sizeof(struct romfs_inode_info), 0,
				  SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD |
				  SLAB_ACCOUNT, romfs_i_init_once);

	if (!romfs_inode_cachep) {
		pr_err("Failed to initialise inode cache\n");
		return -ENOMEM;
	}
	ret = register_filesystem(&romfs_fs_type);
	if (ret) {
		pr_err("Failed to register filesystem\n");
		goto error_register;
	}
	return 0;

error_register:
	kmem_cache_destroy(romfs_inode_cachep);
	return ret;
}

/*
 * romfs module removal
 */
static void __exit exit_romfs_fs(void)
{
	unregister_filesystem(&romfs_fs_type);
	/*
	 * Make sure all delayed rcu free inodes are flushed before we
	 * destroy cache.
	 */
	rcu_barrier();
	kmem_cache_destroy(romfs_inode_cachep);
}

module_init(init_romfs_fs);
module_exit(exit_romfs_fs);

MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */
Commit	Line	Data
da4458bd DH	1	/* Block- or MTD-based romfs
	2	*
	3	* Copyright © 2007 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* Derived from: ROMFS file system, Linux implementation
	7	*
	8	* Copyright © 1997-1999 Janos Farkas <chexum@shadow.banki.hu>
	9	*
	10	* Using parts of the minix filesystem
	11	* Copyright © 1991, 1992 Linus Torvalds
	12	*
	13	* and parts of the affs filesystem additionally
	14	* Copyright © 1993 Ray Burr
	15	* Copyright © 1996 Hans-Joachim Widmaier
	16	*
	17	* Changes
	18	* Changed for 2.1.19 modules
	19	* Jan 1997 Initial release
	20	* Jun 1997 2.1.43+ changes
	21	* Proper page locking in readpage
	22	* Changed to work with 2.1.45+ fs
	23	* Jul 1997 Fixed follow_link
	24	* 2.1.47
	25	* lookup shouldn't return -ENOENT
	26	* from Horst von Brand:
	27	* fail on wrong checksum
	28	* double unlock_super was possible
	29	* correct namelen for statfs
	30	* spotted by Bill Hawes:
	31	* readlink shouldn't iput()
	32	* Jun 1998 2.1.106 from Avery Pennarun: glibc scandir()
	33	* exposed a problem in readdir
	34	* 2.1.107 code-freeze spellchecker run
	35	* Aug 1998 2.1.118+ VFS changes
	36	* Sep 1998 2.1.122 another VFS change (follow_link)
	37	* Apr 1999 2.2.7 no more EBADF checking in
	38	* lookup/readdir, use ERR_PTR
	39	* Jun 1999 2.3.6 d_alloc_root use changed
	40	* 2.3.9 clean up usage of ENOENT/negative
	41	* dentries in lookup
	42	* clean up page flags setting
	43	* (error, uptodate, locking) in
	44	* in readpage
	45	* use init_special_inode for
	46	* fifos/sockets (and streamline) in
	47	* read_inode, fix _ops table order
	48	* Aug 1999 2.3.16 __initfunc() => __init change
	49	* Oct 1999 2.3.24 page->owner hack obsoleted
	50	* Nov 1999 2.3.27 2.3.25+ page->offset => index change
	51	*
	52	*
	53	* This program is free software; you can redistribute it and/or
	54	* modify it under the terms of the GNU General Public Licence
	55	* as published by the Free Software Foundation; either version
	56	* 2 of the Licence, or (at your option) any later version.
	57	*/
	58
ca9e5368 FF	59	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
ca9e5368 FF	60
da4458bd DH	61	#include <linux/module.h>
	62	#include <linux/string.h>
	63	#include <linux/fs.h>
	64	#include <linux/time.h>
	65	#include <linux/slab.h>
	66	#include <linux/init.h>
	67	#include <linux/blkdev.h>
	68	#include <linux/parser.h>
	69	#include <linux/mount.h>
	70	#include <linux/namei.h>
	71	#include <linux/statfs.h>
	72	#include <linux/mtd/super.h>
	73	#include <linux/ctype.h>
	74	#include <linux/highmem.h>
	75	#include <linux/pagemap.h>
	76	#include <linux/uaccess.h>
	77	#include "internal.h"
	78
	79	static struct kmem_cache *romfs_inode_cachep;
	80
	81	static const umode_t romfs_modemap[8] = {
	82	0, /* hard link */
	83	S_IFDIR \| 0644, /* directory */
	84	S_IFREG \| 0644, /* regular file */
	85	S_IFLNK \| 0777, /* symlink */
	86	S_IFBLK \| 0600, /* blockdev */
	87	S_IFCHR \| 0600, /* chardev */
	88	S_IFSOCK \| 0644, /* socket */
	89	S_IFIFO \| 0644 /* FIFO */
	90	};
	91
	92	static const unsigned char romfs_dtype_table[] = {
	93	DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
	94	};
	95
	96	static struct inode romfs_iget(struct super_block sb, unsigned long pos);
	97
	98	/*
	99	* read a page worth of data from the image
	100	*/
	101	static int romfs_readpage(struct file file, struct page page)
	102	{
	103	struct inode *inode = page->mapping->host;
	104	loff_t offset, size;
	105	unsigned long fillsize, pos;
	106	void *buf;
	107	int ret;
	108
	109	buf = kmap(page);
	110	if (!buf)
	111	return -ENOMEM;
	112
	113	/* 32 bit warning -- but not for us :) */
	114	offset = page_offset(page);
	115	size = i_size_read(inode);
	116	fillsize = 0;
	117	ret = 0;
	118	if (offset < size) {
	119	size -= offset;
	120	fillsize = size > PAGE_SIZE ? PAGE_SIZE : size;
	121
	122	pos = ROMFS_I(inode)->i_dataoffset + offset;
	123
	124	ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize);
125	if (ret < 0) {
126	SetPageError(page);
127	fillsize = 0;
128	ret = -EIO;
129	}
130	}
131
132	if (fillsize < PAGE_SIZE)
133	memset(buf + fillsize, 0, PAGE_SIZE - fillsize);
134	if (ret == 0)
135	SetPageUptodate(page);
136
137	flush_dcache_page(page);
138	kunmap(page);
139	unlock_page(page);
140	return ret;
141	}
142
143	static const struct address_space_operations romfs_aops = {
144	.readpage = romfs_readpage
145	};
146
147	/*
148	* read the entries from a directory
149	*/
3903b38c	150	static int romfs_readdir(struct file file, struct dir_context ctx)
da4458bd	151	{
3903b38c	152	struct inode *i = file_inode(file);
da4458bd DH	153	struct romfs_inode ri;
	154	unsigned long offset, maxoff;
	155	int j, ino, nextfh;
da4458bd DH	156	char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
	157	int ret;
	158
	159	maxoff = romfs_maxsize(i->i_sb);
	160
3903b38c	161	offset = ctx->pos;
da4458bd DH	162	if (!offset) {
	163	offset = i->i_ino & ROMFH_MASK;
	164	ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
	165	if (ret < 0)
	166	goto out;
	167	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	168	}
	169
	170	/* Not really failsafe, but we are read-only... */
	171	for (;;) {
	172	if (!offset \|\| offset >= maxoff) {
	173	offset = maxoff;
3903b38c	174	ctx->pos = offset;
da4458bd DH	175	goto out;
da4458bd DH	176	}
3903b38c	177	ctx->pos = offset;
da4458bd DH	178
	179	/* Fetch inode info */
	180	ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
	181	if (ret < 0)
	182	goto out;
	183
	184	j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE,
	185	sizeof(fsname) - 1);
	186	if (j < 0)
	187	goto out;
	188
	189	ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j);
	190	if (ret < 0)
	191	goto out;
	192	fsname[j] = '\0';
	193
	194	ino = offset;
	195	nextfh = be32_to_cpu(ri.next);
	196	if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
	197	ino = be32_to_cpu(ri.spec);
3903b38c AV	198	if (!dir_emit(ctx, fsname, j, ino,
3903b38c AV	199	romfs_dtype_table[nextfh & ROMFH_TYPE]))
da4458bd DH	200	goto out;
da4458bd DH	201
da4458bd DH	202	offset = nextfh & ROMFH_MASK;
da4458bd DH	203	}
da4458bd	204	out:
3903b38c	205	return 0;
da4458bd DH	206	}
	207
	208	/*
	209	* look up an entry in a directory
	210	*/
	211	static struct dentry romfs_lookup(struct inode dir, struct dentry *dentry,
00cd8dd3	212	unsigned int flags)
da4458bd DH	213	{
	214	unsigned long offset, maxoff;
	215	struct inode *inode;
	216	struct romfs_inode ri;
	217	const char name; / got from dentry */
	218	int len, ret;
	219
	220	offset = dir->i_ino & ROMFH_MASK;
	221	ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE);
	222	if (ret < 0)
	223	goto error;
	224
	225	/* search all the file entries in the list starting from the one
	226	* pointed to by the directory's special data */
	227	maxoff = romfs_maxsize(dir->i_sb);
	228	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	229
	230	name = dentry->d_name.name;
	231	len = dentry->d_name.len;
	232
	233	for (;;) {
	234	if (!offset \|\| offset >= maxoff)
	235	goto out0;
	236
	237	ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri));
	238	if (ret < 0)
	239	goto error;
	240
	241	/* try to match the first 16 bytes of name */
84baf74b DH	242	ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,
84baf74b DH	243	len);
da4458bd DH	244	if (ret < 0)
	245	goto error;
	246	if (ret == 1)
	247	break;
	248
	249	/* next entry */
	250	offset = be32_to_cpu(ri.next) & ROMFH_MASK;
	251	}
	252
	253	/* Hard link handling */
	254	if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
	255	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	256
	257	inode = romfs_iget(dir->i_sb, offset);
	258	if (IS_ERR(inode)) {
	259	ret = PTR_ERR(inode);
	260	goto error;
	261	}
	262	goto outi;
	263
	264	/*
	265	* it's a bit funky, _lookup needs to return an error code
	266	* (negative) or a NULL, both as a dentry. ENOENT should not
	267	* be returned, instead we need to create a negative dentry by
	268	* d_add(dentry, NULL); and return 0 as no error.
	269	* (Although as I see, it only matters on writable file
	270	* systems).
	271	*/
	272	out0:
	273	inode = NULL;
	274	outi:
	275	d_add(dentry, inode);
	276	ret = 0;
	277	error:
	278	return ERR_PTR(ret);
	279	}
	280
	281	static const struct file_operations romfs_dir_operations = {
	282	.read = generic_read_dir,
d375570f AV	283	.iterate_shared = romfs_readdir,
d375570f AV	284	.llseek = generic_file_llseek,
da4458bd DH	285	};
da4458bd DH	286
6e1d5dcc	287	static const struct inode_operations romfs_dir_inode_operations = {
da4458bd DH	288	.lookup = romfs_lookup,
	289	};
	290
	291	/*
	292	* get a romfs inode based on its position in the image (which doubles as the
	293	* inode number)
	294	*/
	295	static struct inode romfs_iget(struct super_block sb, unsigned long pos)
	296	{
	297	struct romfs_inode_info *inode;
	298	struct romfs_inode ri;
	299	struct inode *i;
	300	unsigned long nlen;
774e33e7 RK	301	unsigned nextfh;
774e33e7 RK	302	int ret;
da4458bd DH	303	umode_t mode;
	304
	305	/* we might have to traverse a chain of "hard link" file entries to get
	306	* to the actual file */
	307	for (;;) {
	308	ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));
	309	if (ret < 0)
	310	goto error;
	311
	312	/* XXX: do romfs_checksum here too (with name) */
	313
	314	nextfh = be32_to_cpu(ri.next);
	315	if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
	316	break;
	317
	318	pos = be32_to_cpu(ri.spec) & ROMFH_MASK;
	319	}
	320
	321	/* determine the length of the filename */
	322	nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);
	323	if (IS_ERR_VALUE(nlen))
	324	goto eio;
	325
	326	/* get an inode for this image position */
	327	i = iget_locked(sb, pos);
	328	if (!i)
	329	return ERR_PTR(-ENOMEM);
	330
	331	if (!(i->i_state & I_NEW))
	332	return i;
	333
	334	/* precalculate the data offset */
	335	inode = ROMFS_I(i);
	336	inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;
	337	inode->i_dataoffset = pos + inode->i_metasize;
	338
bfe86848	339	set_nlink(i, 1); /* Hard to decide.. */
da4458bd DH	340	i->i_size = be32_to_cpu(ri.size);
	341	i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
	342	i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0;
	343
	344	/* set up mode and ops */
	345	mode = romfs_modemap[nextfh & ROMFH_TYPE];
	346
	347	switch (nextfh & ROMFH_TYPE) {
	348	case ROMFH_DIR:
	349	i->i_size = ROMFS_I(i)->i_metasize;
	350	i->i_op = &romfs_dir_inode_operations;
	351	i->i_fop = &romfs_dir_operations;
	352	if (nextfh & ROMFH_EXEC)
	353	mode \|= S_IXUGO;
	354	break;
	355	case ROMFH_REG:
	356	i->i_fop = &romfs_ro_fops;
	357	i->i_data.a_ops = &romfs_aops;
da4458bd DH	358	if (nextfh & ROMFH_EXEC)
	359	mode \|= S_IXUGO;
	360	break;
	361	case ROMFH_SYM:
	362	i->i_op = &page_symlink_inode_operations;
21fc61c7	363	inode_nohighmem(i);
da4458bd DH	364	i->i_data.a_ops = &romfs_aops;
	365	mode \|= S_IRWXUGO;
	366	break;
	367	default:
	368	/* depending on MBZ for sock/fifos */
	369	nextfh = be32_to_cpu(ri.spec);
	370	init_special_inode(i, mode, MKDEV(nextfh >> 16,
	371	nextfh & 0xffff));
	372	break;
	373	}
	374
	375	i->i_mode = mode;
	376
	377	unlock_new_inode(i);
	378	return i;
	379
	380	eio:
	381	ret = -EIO;
	382	error:
ca9e5368	383	pr_err("read error for inode 0x%lx\n", pos);
da4458bd DH	384	return ERR_PTR(ret);
	385	}
	386
	387	/*
	388	* allocate a new inode
	389	*/
	390	static struct inode romfs_alloc_inode(struct super_block sb)
	391	{
	392	struct romfs_inode_info *inode;
b6d53b1b	393
da4458bd DH	394	inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL);
	395	return inode ? &inode->vfs_inode : NULL;
	396	}
	397
	398	/*
	399	* return a spent inode to the slab cache
	400	*/
fa0d7e3d	401	static void romfs_i_callback(struct rcu_head *head)
da4458bd	402	{
fa0d7e3d	403	struct inode *inode = container_of(head, struct inode, i_rcu);
b6d53b1b	404
da4458bd DH	405	kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
	406	}
	407
fa0d7e3d NP	408	static void romfs_destroy_inode(struct inode *inode)
	409	{
	410	call_rcu(&inode->i_rcu, romfs_i_callback);
	411	}
	412
da4458bd DH	413	/*
	414	* get filesystem statistics
	415	*/
	416	static int romfs_statfs(struct dentry dentry, struct kstatfs buf)
	417	{
8a59f5d2 CL	418	struct super_block *sb = dentry->d_sb;
	419	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
	420
da4458bd DH	421	buf->f_type = ROMFS_MAGIC;
	422	buf->f_namelen = ROMFS_MAXFN;
	423	buf->f_bsize = ROMBSIZE;
	424	buf->f_bfree = buf->f_bavail = buf->f_ffree;
	425	buf->f_blocks =
	426	(romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;
8a59f5d2 CL	427	buf->f_fsid.val[0] = (u32)id;
8a59f5d2 CL	428	buf->f_fsid.val[1] = (u32)(id >> 32);
da4458bd DH	429	return 0;
	430	}
	431
	432	/*
	433	* remounting must involve read-only
	434	*/
	435	static int romfs_remount(struct super_block sb, int flags, char *data)
	436	{
02b9984d	437	sync_filesystem(sb);
da4458bd DH	438	*flags \|= MS_RDONLY;
	439	return 0;
	440	}
	441
	442	static const struct super_operations romfs_super_ops = {
	443	.alloc_inode = romfs_alloc_inode,
	444	.destroy_inode = romfs_destroy_inode,
	445	.statfs = romfs_statfs,
	446	.remount_fs = romfs_remount,
	447	};
	448
	449	/*
	450	* checksum check on part of a romfs filesystem
	451	*/
	452	static __u32 romfs_checksum(const void *data, int size)
	453	{
	454	const __be32 *ptr = data;
	455	__u32 sum;
	456
	457	sum = 0;
	458	size >>= 2;
	459	while (size > 0) {
	460	sum += be32_to_cpu(*ptr++);
	461	size--;
	462	}
	463	return sum;
	464	}
	465
	466	/*
	467	* fill in the superblock
	468	*/
	469	static int romfs_fill_super(struct super_block sb, void data, int silent)
	470	{
	471	struct romfs_super_block *rsb;
	472	struct inode *root;
	473	unsigned long pos, img_size;
	474	const char *storage;
	475	size_t len;
	476	int ret;
	477
	478	#ifdef CONFIG_BLOCK
	479	if (!sb->s_mtd) {
	480	sb_set_blocksize(sb, ROMBSIZE);
	481	} else {
	482	sb->s_blocksize = ROMBSIZE;
	483	sb->s_blocksize_bits = blksize_bits(ROMBSIZE);
	484	}
	485	#endif
	486
	487	sb->s_maxbytes = 0xFFFFFFFF;
	488	sb->s_magic = ROMFS_MAGIC;
	489	sb->s_flags \|= MS_RDONLY \| MS_NOATIME;
	490	sb->s_op = &romfs_super_ops;
	491
	492	/* read the image superblock and check it */
	493	rsb = kmalloc(512, GFP_KERNEL);
	494	if (!rsb)
	495	return -ENOMEM;
	496
	497	sb->s_fs_info = (void *) 512;
	498	ret = romfs_dev_read(sb, 0, rsb, 512);
	499	if (ret < 0)
	500	goto error_rsb;
	501
502	img_size = be32_to_cpu(rsb->size);
503
504	if (sb->s_mtd && img_size > sb->s_mtd->size)
505	goto error_rsb_inval;
506
507	sb->s_fs_info = (void *) img_size;
508
509	if (rsb->word0 != ROMSB_WORD0 \|\| rsb->word1 != ROMSB_WORD1 \|\|
510	img_size < ROMFH_SIZE) {
511	if (!silent)
3d79d314	512	pr_warn("VFS: Can't find a romfs filesystem on dev %s.\n",
da4458bd DH	513	sb->s_id);
	514	goto error_rsb_inval;
	515	}
	516
	517	if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
ca9e5368	518	pr_err("bad initial checksum on dev %s.\n", sb->s_id);
da4458bd DH	519	goto error_rsb_inval;
	520	}
	521
	522	storage = sb->s_mtd ? "MTD" : "the block layer";
	523
	524	len = strnlen(rsb->name, ROMFS_MAXFN);
	525	if (!silent)
ca9e5368 FF	526	pr_notice("Mounting image '%.s' through %s\n",
ca9e5368 FF	527	(unsigned) len, (unsigned) len, rsb->name, storage);
da4458bd DH	528
	529	kfree(rsb);
	530	rsb = NULL;
	531
	532	/* find the root directory */
	533	pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;
	534
	535	root = romfs_iget(sb, pos);
a21f3c2a	536	if (IS_ERR(root))
40e2c71d	537	return PTR_ERR(root);
da4458bd	538
48fde701	539	sb->s_root = d_make_root(root);
da4458bd	540	if (!sb->s_root)
40e2c71d	541	return -ENOMEM;
da4458bd DH	542
	543	return 0;
	544
da4458bd DH	545	error_rsb_inval:
	546	ret = -EINVAL;
	547	error_rsb:
7e32b7bb	548	kfree(rsb);
da4458bd DH	549	return ret;
	550	}
	551
	552	/*
	553	* get a superblock for mounting
	554	*/
848b83a5	555	static struct dentry romfs_mount(struct file_system_type fs_type,
da4458bd	556	int flags, const char *dev_name,
848b83a5	557	void *data)
da4458bd	558	{
848b83a5	559	struct dentry *ret = ERR_PTR(-EINVAL);
da4458bd DH	560
da4458bd DH	561	#ifdef CONFIG_ROMFS_ON_MTD
848b83a5	562	ret = mount_mtd(fs_type, flags, dev_name, data, romfs_fill_super);
da4458bd DH	563	#endif
da4458bd DH	564	#ifdef CONFIG_ROMFS_ON_BLOCK
848b83a5 AV	565	if (ret == ERR_PTR(-EINVAL))
	566	ret = mount_bdev(fs_type, flags, dev_name, data,
	567	romfs_fill_super);
da4458bd DH	568	#endif
	569	return ret;
	570	}
	571
	572	/*
	573	* destroy a romfs superblock in the appropriate manner
	574	*/
	575	static void romfs_kill_sb(struct super_block *sb)
	576	{
	577	#ifdef CONFIG_ROMFS_ON_MTD
	578	if (sb->s_mtd) {
	579	kill_mtd_super(sb);
	580	return;
	581	}
	582	#endif
	583	#ifdef CONFIG_ROMFS_ON_BLOCK
	584	if (sb->s_bdev) {
	585	kill_block_super(sb);
	586	return;
	587	}
	588	#endif
	589	}
	590
	591	static struct file_system_type romfs_fs_type = {
	592	.owner = THIS_MODULE,
	593	.name = "romfs",
848b83a5	594	.mount = romfs_mount,
da4458bd DH	595	.kill_sb = romfs_kill_sb,
	596	.fs_flags = FS_REQUIRES_DEV,
	597	};
7f78e035	598	MODULE_ALIAS_FS("romfs");
da4458bd DH	599
	600	/*
	601	* inode storage initialiser
	602	*/
	603	static void romfs_i_init_once(void *_inode)
	604	{
	605	struct romfs_inode_info *inode = _inode;
	606
	607	inode_init_once(&inode->vfs_inode);
	608	}
	609
	610	/*
	611	* romfs module initialisation
	612	*/
	613	static int __init init_romfs_fs(void)
	614	{
	615	int ret;
	616
3d79d314	617	pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n");
da4458bd DH	618
	619	romfs_inode_cachep =
	620	kmem_cache_create("romfs_i",
	621	sizeof(struct romfs_inode_info), 0,
5d097056 VD	622	SLAB_RECLAIM_ACCOUNT \| SLAB_MEM_SPREAD \|
5d097056 VD	623	SLAB_ACCOUNT, romfs_i_init_once);
da4458bd DH	624
da4458bd DH	625	if (!romfs_inode_cachep) {
ca9e5368	626	pr_err("Failed to initialise inode cache\n");
da4458bd DH	627	return -ENOMEM;
	628	}
	629	ret = register_filesystem(&romfs_fs_type);
	630	if (ret) {
ca9e5368	631	pr_err("Failed to register filesystem\n");
da4458bd DH	632	goto error_register;
	633	}
	634	return 0;
	635
	636	error_register:
	637	kmem_cache_destroy(romfs_inode_cachep);
	638	return ret;
	639	}
	640
	641	/*
	642	* romfs module removal
	643	*/
	644	static void __exit exit_romfs_fs(void)
	645	{
	646	unregister_filesystem(&romfs_fs_type);
8c0a8537 KS	647	/*
	648	* Make sure all delayed rcu free inodes are flushed before we
	649	* destroy cache.
	650	*/
	651	rcu_barrier();
da4458bd DH	652	kmem_cache_destroy(romfs_inode_cachep);
	653	}
	654
	655	module_init(init_romfs_fs);
	656	module_exit(exit_romfs_fs);
	657
	658	MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
	659	MODULE_AUTHOR("Red Hat, Inc.");
	660	MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */