[deliverable/linux.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.
 */

#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	= romfs_readdir,
	.llseek		= default_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 (i->i_sb->s_mtd)
			i->i_data.backing_dev_info =
				i->i_sb->s_mtd->backing_dev_info;
		if (nextfh & ROMFH_EXEC)
			mode |= S_IXUGO;
		break;
	case ROMFH_SYM:
		i->i_op = &page_symlink_inode_operations;
		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:
	printk(KERN_ERR "ROMFS: 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)
{
	*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)
			printk(KERN_WARNING "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))) {
		printk(KERN_ERR "ROMFS: 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)
		printk(KERN_NOTICE "ROMFS: 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))
		goto error;

	sb->s_root = d_make_root(root);
	if (!sb->s_root)
		goto error;

	return 0;

error:
	return -EINVAL;
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;

	printk(KERN_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,
				  romfs_i_init_once);

	if (!romfs_inode_cachep) {
		printk(KERN_ERR
		       "ROMFS error: Failed to initialise inode cache\n");
		return -ENOMEM;
	}
	ret = register_filesystem(&romfs_fs_type);
	if (ret) {
		printk(KERN_ERR "ROMFS error: 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
	59	#include <linux/module.h>
	60	#include <linux/string.h>
	61	#include <linux/fs.h>
	62	#include <linux/time.h>
	63	#include <linux/slab.h>
	64	#include <linux/init.h>
65	#include <linux/blkdev.h>
66	#include <linux/parser.h>
67	#include <linux/mount.h>
68	#include <linux/namei.h>
69	#include <linux/statfs.h>
70	#include <linux/mtd/super.h>
71	#include <linux/ctype.h>
72	#include <linux/highmem.h>
73	#include <linux/pagemap.h>
74	#include <linux/uaccess.h>
75	#include "internal.h"
76
77	static struct kmem_cache *romfs_inode_cachep;
78
79	static const umode_t romfs_modemap[8] = {
80	0, /* hard link */
81	S_IFDIR \| 0644, /* directory */
82	S_IFREG \| 0644, /* regular file */
83	S_IFLNK \| 0777, /* symlink */
84	S_IFBLK \| 0600, /* blockdev */
85	S_IFCHR \| 0600, /* chardev */
86	S_IFSOCK \| 0644, /* socket */
87	S_IFIFO \| 0644 /* FIFO */
88	};
89
90	static const unsigned char romfs_dtype_table[] = {
91	DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
92	};
93
94	static struct inode romfs_iget(struct super_block sb, unsigned long pos);
95
96	/*
97	* read a page worth of data from the image
98	*/
99	static int romfs_readpage(struct file file, struct page page)
100	{
101	struct inode *inode = page->mapping->host;
102	loff_t offset, size;
103	unsigned long fillsize, pos;
104	void *buf;
105	int ret;
106
107	buf = kmap(page);
108	if (!buf)
109	return -ENOMEM;
110
111	/* 32 bit warning -- but not for us :) */
112	offset = page_offset(page);
113	size = i_size_read(inode);
114	fillsize = 0;
115	ret = 0;
116	if (offset < size) {
117	size -= offset;
118	fillsize = size > PAGE_SIZE ? PAGE_SIZE : size;
119
120	pos = ROMFS_I(inode)->i_dataoffset + offset;
121
122	ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize);
123	if (ret < 0) {
124	SetPageError(page);
125	fillsize = 0;
126	ret = -EIO;
127	}
128	}
129
130	if (fillsize < PAGE_SIZE)
131	memset(buf + fillsize, 0, PAGE_SIZE - fillsize);
132	if (ret == 0)
133	SetPageUptodate(page);
134
135	flush_dcache_page(page);
136	kunmap(page);
137	unlock_page(page);
138	return ret;
139	}
140
141	static const struct address_space_operations romfs_aops = {
142	.readpage = romfs_readpage
143	};
144
145	/*
146	* read the entries from a directory
147	*/
3903b38c	148	static int romfs_readdir(struct file file, struct dir_context ctx)
da4458bd	149	{
3903b38c	150	struct inode *i = file_inode(file);
da4458bd DH	151	struct romfs_inode ri;
	152	unsigned long offset, maxoff;
	153	int j, ino, nextfh;
da4458bd DH	154	char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
	155	int ret;
	156
	157	maxoff = romfs_maxsize(i->i_sb);
	158
3903b38c	159	offset = ctx->pos;
da4458bd DH	160	if (!offset) {
	161	offset = i->i_ino & ROMFH_MASK;
	162	ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
	163	if (ret < 0)
	164	goto out;
	165	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	166	}
	167
	168	/* Not really failsafe, but we are read-only... */
	169	for (;;) {
	170	if (!offset \|\| offset >= maxoff) {
	171	offset = maxoff;
3903b38c	172	ctx->pos = offset;
da4458bd DH	173	goto out;
da4458bd DH	174	}
3903b38c	175	ctx->pos = offset;
da4458bd DH	176
	177	/* Fetch inode info */
	178	ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
	179	if (ret < 0)
	180	goto out;
	181
	182	j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE,
	183	sizeof(fsname) - 1);
	184	if (j < 0)
	185	goto out;
	186
	187	ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j);
	188	if (ret < 0)
	189	goto out;
	190	fsname[j] = '\0';
	191
	192	ino = offset;
	193	nextfh = be32_to_cpu(ri.next);
	194	if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
	195	ino = be32_to_cpu(ri.spec);
3903b38c AV	196	if (!dir_emit(ctx, fsname, j, ino,
3903b38c AV	197	romfs_dtype_table[nextfh & ROMFH_TYPE]))
da4458bd DH	198	goto out;
da4458bd DH	199
da4458bd DH	200	offset = nextfh & ROMFH_MASK;
da4458bd DH	201	}
da4458bd	202	out:
3903b38c	203	return 0;
da4458bd DH	204	}
	205
	206	/*
	207	* look up an entry in a directory
	208	*/
	209	static struct dentry romfs_lookup(struct inode dir, struct dentry *dentry,
00cd8dd3	210	unsigned int flags)
da4458bd DH	211	{
	212	unsigned long offset, maxoff;
	213	struct inode *inode;
	214	struct romfs_inode ri;
	215	const char name; / got from dentry */
	216	int len, ret;
	217
	218	offset = dir->i_ino & ROMFH_MASK;
	219	ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE);
	220	if (ret < 0)
	221	goto error;
	222
	223	/* search all the file entries in the list starting from the one
	224	* pointed to by the directory's special data */
	225	maxoff = romfs_maxsize(dir->i_sb);
	226	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	227
	228	name = dentry->d_name.name;
	229	len = dentry->d_name.len;
	230
	231	for (;;) {
	232	if (!offset \|\| offset >= maxoff)
	233	goto out0;
	234
	235	ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri));
	236	if (ret < 0)
	237	goto error;
	238
	239	/* try to match the first 16 bytes of name */
84baf74b DH	240	ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,
84baf74b DH	241	len);
da4458bd DH	242	if (ret < 0)
	243	goto error;
	244	if (ret == 1)
	245	break;
	246
	247	/* next entry */
	248	offset = be32_to_cpu(ri.next) & ROMFH_MASK;
	249	}
	250
	251	/* Hard link handling */
	252	if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
	253	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	254
	255	inode = romfs_iget(dir->i_sb, offset);
	256	if (IS_ERR(inode)) {
	257	ret = PTR_ERR(inode);
	258	goto error;
	259	}
	260	goto outi;
	261
	262	/*
	263	* it's a bit funky, _lookup needs to return an error code
	264	* (negative) or a NULL, both as a dentry. ENOENT should not
	265	* be returned, instead we need to create a negative dentry by
	266	* d_add(dentry, NULL); and return 0 as no error.
	267	* (Although as I see, it only matters on writable file
	268	* systems).
	269	*/
	270	out0:
	271	inode = NULL;
	272	outi:
	273	d_add(dentry, inode);
	274	ret = 0;
	275	error:
	276	return ERR_PTR(ret);
	277	}
	278
	279	static const struct file_operations romfs_dir_operations = {
	280	.read = generic_read_dir,
3903b38c	281	.iterate = romfs_readdir,
6038f373	282	.llseek = default_llseek,
da4458bd DH	283	};
da4458bd DH	284
6e1d5dcc	285	static const struct inode_operations romfs_dir_inode_operations = {
da4458bd DH	286	.lookup = romfs_lookup,
	287	};
	288
	289	/*
	290	* get a romfs inode based on its position in the image (which doubles as the
	291	* inode number)
	292	*/
	293	static struct inode romfs_iget(struct super_block sb, unsigned long pos)
	294	{
	295	struct romfs_inode_info *inode;
	296	struct romfs_inode ri;
	297	struct inode *i;
	298	unsigned long nlen;
774e33e7 RK	299	unsigned nextfh;
774e33e7 RK	300	int ret;
da4458bd DH	301	umode_t mode;
	302
	303	/* we might have to traverse a chain of "hard link" file entries to get
	304	* to the actual file */
	305	for (;;) {
	306	ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));
	307	if (ret < 0)
	308	goto error;
	309
	310	/* XXX: do romfs_checksum here too (with name) */
	311
	312	nextfh = be32_to_cpu(ri.next);
	313	if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
	314	break;
	315
	316	pos = be32_to_cpu(ri.spec) & ROMFH_MASK;
	317	}
	318
	319	/* determine the length of the filename */
	320	nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);
	321	if (IS_ERR_VALUE(nlen))
	322	goto eio;
	323
	324	/* get an inode for this image position */
	325	i = iget_locked(sb, pos);
	326	if (!i)
	327	return ERR_PTR(-ENOMEM);
	328
	329	if (!(i->i_state & I_NEW))
	330	return i;
	331
	332	/* precalculate the data offset */
	333	inode = ROMFS_I(i);
	334	inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;
	335	inode->i_dataoffset = pos + inode->i_metasize;
	336
bfe86848	337	set_nlink(i, 1); /* Hard to decide.. */
da4458bd DH	338	i->i_size = be32_to_cpu(ri.size);
	339	i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
	340	i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0;
	341
	342	/* set up mode and ops */
	343	mode = romfs_modemap[nextfh & ROMFH_TYPE];
	344
	345	switch (nextfh & ROMFH_TYPE) {
	346	case ROMFH_DIR:
	347	i->i_size = ROMFS_I(i)->i_metasize;
	348	i->i_op = &romfs_dir_inode_operations;
	349	i->i_fop = &romfs_dir_operations;
	350	if (nextfh & ROMFH_EXEC)
	351	mode \|= S_IXUGO;
	352	break;
	353	case ROMFH_REG:
	354	i->i_fop = &romfs_ro_fops;
	355	i->i_data.a_ops = &romfs_aops;
	356	if (i->i_sb->s_mtd)
	357	i->i_data.backing_dev_info =
	358	i->i_sb->s_mtd->backing_dev_info;
	359	if (nextfh & ROMFH_EXEC)
	360	mode \|= S_IXUGO;
	361	break;
	362	case ROMFH_SYM:
	363	i->i_op = &page_symlink_inode_operations;
	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:
	383	printk(KERN_ERR "ROMFS: read error for inode 0x%lx\n", pos);
	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;
	393	inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL);
	394	return inode ? &inode->vfs_inode : NULL;
	395	}
	396
	397	/*
	398	* return a spent inode to the slab cache
	399	*/
fa0d7e3d	400	static void romfs_i_callback(struct rcu_head *head)
da4458bd	401	{
fa0d7e3d	402	struct inode *inode = container_of(head, struct inode, i_rcu);
da4458bd DH	403	kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
	404	}
	405
fa0d7e3d NP	406	static void romfs_destroy_inode(struct inode *inode)
	407	{
	408	call_rcu(&inode->i_rcu, romfs_i_callback);
	409	}
	410
da4458bd DH	411	/*
	412	* get filesystem statistics
	413	*/
	414	static int romfs_statfs(struct dentry dentry, struct kstatfs buf)
	415	{
8a59f5d2 CL	416	struct super_block *sb = dentry->d_sb;
	417	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
	418
da4458bd DH	419	buf->f_type = ROMFS_MAGIC;
	420	buf->f_namelen = ROMFS_MAXFN;
	421	buf->f_bsize = ROMBSIZE;
	422	buf->f_bfree = buf->f_bavail = buf->f_ffree;
	423	buf->f_blocks =
	424	(romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;
8a59f5d2 CL	425	buf->f_fsid.val[0] = (u32)id;
8a59f5d2 CL	426	buf->f_fsid.val[1] = (u32)(id >> 32);
da4458bd DH	427	return 0;
	428	}
	429
	430	/*
	431	* remounting must involve read-only
	432	*/
	433	static int romfs_remount(struct super_block sb, int flags, char *data)
	434	{
	435	*flags \|= MS_RDONLY;
	436	return 0;
	437	}
	438
	439	static const struct super_operations romfs_super_ops = {
	440	.alloc_inode = romfs_alloc_inode,
	441	.destroy_inode = romfs_destroy_inode,
	442	.statfs = romfs_statfs,
	443	.remount_fs = romfs_remount,
	444	};
	445
	446	/*
	447	* checksum check on part of a romfs filesystem
	448	*/
	449	static __u32 romfs_checksum(const void *data, int size)
	450	{
	451	const __be32 *ptr = data;
	452	__u32 sum;
	453
	454	sum = 0;
	455	size >>= 2;
	456	while (size > 0) {
	457	sum += be32_to_cpu(*ptr++);
	458	size--;
	459	}
	460	return sum;
	461	}
	462
	463	/*
	464	* fill in the superblock
	465	*/
	466	static int romfs_fill_super(struct super_block sb, void data, int silent)
	467	{
	468	struct romfs_super_block *rsb;
	469	struct inode *root;
	470	unsigned long pos, img_size;
	471	const char *storage;
	472	size_t len;
	473	int ret;
	474
	475	#ifdef CONFIG_BLOCK
	476	if (!sb->s_mtd) {
	477	sb_set_blocksize(sb, ROMBSIZE);
	478	} else {
	479	sb->s_blocksize = ROMBSIZE;
	480	sb->s_blocksize_bits = blksize_bits(ROMBSIZE);
	481	}
	482	#endif
	483
	484	sb->s_maxbytes = 0xFFFFFFFF;
	485	sb->s_magic = ROMFS_MAGIC;
	486	sb->s_flags \|= MS_RDONLY \| MS_NOATIME;
	487	sb->s_op = &romfs_super_ops;
	488
	489	/* read the image superblock and check it */
	490	rsb = kmalloc(512, GFP_KERNEL);
491	if (!rsb)
492	return -ENOMEM;
493
494	sb->s_fs_info = (void *) 512;
495	ret = romfs_dev_read(sb, 0, rsb, 512);
496	if (ret < 0)
497	goto error_rsb;
498
499	img_size = be32_to_cpu(rsb->size);
500
501	if (sb->s_mtd && img_size > sb->s_mtd->size)
502	goto error_rsb_inval;
503
504	sb->s_fs_info = (void *) img_size;
505
506	if (rsb->word0 != ROMSB_WORD0 \|\| rsb->word1 != ROMSB_WORD1 \|\|
507	img_size < ROMFH_SIZE) {
508	if (!silent)
509	printk(KERN_WARNING "VFS:"
510	" Can't find a romfs filesystem on dev %s.\n",
511	sb->s_id);
512	goto error_rsb_inval;
513	}
514
515	if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
516	printk(KERN_ERR "ROMFS: bad initial checksum on dev %s.\n",
517	sb->s_id);
518	goto error_rsb_inval;
519	}
520
521	storage = sb->s_mtd ? "MTD" : "the block layer";
522
523	len = strnlen(rsb->name, ROMFS_MAXFN);
524	if (!silent)
525	printk(KERN_NOTICE "ROMFS: Mounting image '%.s' through %s\n",
526	(unsigned) len, (unsigned) len, rsb->name, storage);
527
528	kfree(rsb);
529	rsb = NULL;
530
531	/* find the root directory */
532	pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;
533
534	root = romfs_iget(sb, pos);
a21f3c2a	535	if (IS_ERR(root))
da4458bd DH	536	goto error;
da4458bd DH	537
48fde701	538	sb->s_root = d_make_root(root);
da4458bd	539	if (!sb->s_root)
48fde701	540	goto error;
da4458bd DH	541
	542	return 0;
	543
da4458bd DH	544	error:
	545	return -EINVAL;
	546	error_rsb_inval:
	547	ret = -EINVAL;
	548	error_rsb:
7e32b7bb	549	kfree(rsb);
da4458bd DH	550	return ret;
	551	}
	552
	553	/*
	554	* get a superblock for mounting
	555	*/
848b83a5	556	static struct dentry romfs_mount(struct file_system_type fs_type,
da4458bd	557	int flags, const char *dev_name,
848b83a5	558	void *data)
da4458bd	559	{
848b83a5	560	struct dentry *ret = ERR_PTR(-EINVAL);
da4458bd DH	561
da4458bd DH	562	#ifdef CONFIG_ROMFS_ON_MTD
848b83a5	563	ret = mount_mtd(fs_type, flags, dev_name, data, romfs_fill_super);
da4458bd DH	564	#endif
da4458bd DH	565	#ifdef CONFIG_ROMFS_ON_BLOCK
848b83a5 AV	566	if (ret == ERR_PTR(-EINVAL))
	567	ret = mount_bdev(fs_type, flags, dev_name, data,
	568	romfs_fill_super);
da4458bd DH	569	#endif
	570	return ret;
	571	}
	572
	573	/*
	574	* destroy a romfs superblock in the appropriate manner
	575	*/
	576	static void romfs_kill_sb(struct super_block *sb)
	577	{
	578	#ifdef CONFIG_ROMFS_ON_MTD
	579	if (sb->s_mtd) {
	580	kill_mtd_super(sb);
	581	return;
	582	}
	583	#endif
	584	#ifdef CONFIG_ROMFS_ON_BLOCK
	585	if (sb->s_bdev) {
	586	kill_block_super(sb);
	587	return;
	588	}
	589	#endif
	590	}
	591
	592	static struct file_system_type romfs_fs_type = {
	593	.owner = THIS_MODULE,
	594	.name = "romfs",
848b83a5	595	.mount = romfs_mount,
da4458bd DH	596	.kill_sb = romfs_kill_sb,
	597	.fs_flags = FS_REQUIRES_DEV,
	598	};
7f78e035	599	MODULE_ALIAS_FS("romfs");
da4458bd DH	600
	601	/*
	602	* inode storage initialiser
	603	*/
	604	static void romfs_i_init_once(void *_inode)
	605	{
	606	struct romfs_inode_info *inode = _inode;
	607
	608	inode_init_once(&inode->vfs_inode);
	609	}
	610
	611	/*
	612	* romfs module initialisation
	613	*/
	614	static int __init init_romfs_fs(void)
	615	{
	616	int ret;
	617
	618	printk(KERN_INFO "ROMFS MTD (C) 2007 Red Hat, Inc.\n");
	619
	620	romfs_inode_cachep =
	621	kmem_cache_create("romfs_i",
	622	sizeof(struct romfs_inode_info), 0,
	623	SLAB_RECLAIM_ACCOUNT \| SLAB_MEM_SPREAD,
	624	romfs_i_init_once);
	625
	626	if (!romfs_inode_cachep) {
	627	printk(KERN_ERR
	628	"ROMFS error: Failed to initialise inode cache\n");
	629	return -ENOMEM;
	630	}
	631	ret = register_filesystem(&romfs_fs_type);
	632	if (ret) {
	633	printk(KERN_ERR "ROMFS error: Failed to register filesystem\n");
	634	goto error_register;
	635	}
	636	return 0;
	637
	638	error_register:
	639	kmem_cache_destroy(romfs_inode_cachep);
	640	return ret;
	641	}
	642
	643	/*
	644	* romfs module removal
	645	*/
	646	static void __exit exit_romfs_fs(void)
	647	{
	648	unregister_filesystem(&romfs_fs_type);
8c0a8537 KS	649	/*
	650	* Make sure all delayed rcu free inodes are flushed before we
	651	* destroy cache.
	652	*/
	653	rcu_barrier();
da4458bd DH	654	kmem_cache_destroy(romfs_inode_cachep);
	655	}
	656
	657	module_init(init_romfs_fs);
	658	module_exit(exit_romfs_fs);
	659
	660	MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
	661	MODULE_AUTHOR("Red Hat, Inc.");
	662	MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */