[mirror_ubuntu-bionic-kernel.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 <linux/major.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 = 0;

	/* When calling huge_encode_dev(),
	 * use sb->s_bdev->bd_dev when,
	 *   - CONFIG_ROMFS_ON_BLOCK defined
	 * use sb->s_dev when,
	 *   - CONFIG_ROMFS_ON_BLOCK undefined and
	 *   - CONFIG_ROMFS_ON_MTD defined
	 * leave id as 0 when,
	 *   - CONFIG_ROMFS_ON_BLOCK undefined and
	 *   - CONFIG_ROMFS_ON_MTD undefined
	 */
	if (sb->s_bdev)
		id = huge_encode_dev(sb->s_bdev->bd_dev);
	else if (sb->s_dev)
		id = huge_encode_dev(sb->s_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 |= SB_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 |= SB_RDONLY | SB_NOATIME;
	sb->s_op = &romfs_super_ops;

#ifdef CONFIG_ROMFS_ON_MTD
	/* Use same dev ID from the underlying mtdblock device */
	if (sb->s_mtd)
		sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
#endif
	/* 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>
f598f82e	77	#include <linux/major.h>
da4458bd DH	78	#include "internal.h"
	79
	80	static struct kmem_cache *romfs_inode_cachep;
	81
	82	static const umode_t romfs_modemap[8] = {
	83	0, /* hard link */
	84	S_IFDIR \| 0644, /* directory */
	85	S_IFREG \| 0644, /* regular file */
	86	S_IFLNK \| 0777, /* symlink */
	87	S_IFBLK \| 0600, /* blockdev */
	88	S_IFCHR \| 0600, /* chardev */
	89	S_IFSOCK \| 0644, /* socket */
	90	S_IFIFO \| 0644 /* FIFO */
	91	};
	92
	93	static const unsigned char romfs_dtype_table[] = {
	94	DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
	95	};
	96
	97	static struct inode romfs_iget(struct super_block sb, unsigned long pos);
	98
	99	/*
	100	* read a page worth of data from the image
	101	*/
	102	static int romfs_readpage(struct file file, struct page page)
	103	{
	104	struct inode *inode = page->mapping->host;
	105	loff_t offset, size;
	106	unsigned long fillsize, pos;
	107	void *buf;
	108	int ret;
	109
	110	buf = kmap(page);
	111	if (!buf)
	112	return -ENOMEM;
	113
	114	/* 32 bit warning -- but not for us :) */
	115	offset = page_offset(page);
	116	size = i_size_read(inode);
	117	fillsize = 0;
	118	ret = 0;
	119	if (offset < size) {
	120	size -= offset;
	121	fillsize = size > PAGE_SIZE ? PAGE_SIZE : size;
	122
	123	pos = ROMFS_I(inode)->i_dataoffset + offset;
	124
	125	ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize);
	126	if (ret < 0) {
	127	SetPageError(page);
	128	fillsize = 0;
	129	ret = -EIO;
	130	}
	131	}
	132
	133	if (fillsize < PAGE_SIZE)
	134	memset(buf + fillsize, 0, PAGE_SIZE - fillsize);
	135	if (ret == 0)
	136	SetPageUptodate(page);
	137
	138	flush_dcache_page(page);
	139	kunmap(page);
	140	unlock_page(page);
	141	return ret;
142	}
143
144	static const struct address_space_operations romfs_aops = {
145	.readpage = romfs_readpage
146	};
147
148	/*
149	* read the entries from a directory
150	*/
3903b38c	151	static int romfs_readdir(struct file file, struct dir_context ctx)
da4458bd	152	{
3903b38c	153	struct inode *i = file_inode(file);
da4458bd DH	154	struct romfs_inode ri;
	155	unsigned long offset, maxoff;
	156	int j, ino, nextfh;
da4458bd DH	157	char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
	158	int ret;
	159
	160	maxoff = romfs_maxsize(i->i_sb);
	161
3903b38c	162	offset = ctx->pos;
da4458bd DH	163	if (!offset) {
	164	offset = i->i_ino & ROMFH_MASK;
	165	ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
	166	if (ret < 0)
	167	goto out;
	168	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	169	}
	170
	171	/* Not really failsafe, but we are read-only... */
	172	for (;;) {
	173	if (!offset \|\| offset >= maxoff) {
	174	offset = maxoff;
3903b38c	175	ctx->pos = offset;
da4458bd DH	176	goto out;
da4458bd DH	177	}
3903b38c	178	ctx->pos = offset;
da4458bd DH	179
	180	/* Fetch inode info */
	181	ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
	182	if (ret < 0)
	183	goto out;
	184
	185	j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE,
	186	sizeof(fsname) - 1);
	187	if (j < 0)
	188	goto out;
	189
	190	ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j);
	191	if (ret < 0)
	192	goto out;
	193	fsname[j] = '\0';
	194
	195	ino = offset;
	196	nextfh = be32_to_cpu(ri.next);
	197	if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
	198	ino = be32_to_cpu(ri.spec);
3903b38c AV	199	if (!dir_emit(ctx, fsname, j, ino,
3903b38c AV	200	romfs_dtype_table[nextfh & ROMFH_TYPE]))
da4458bd DH	201	goto out;
da4458bd DH	202
da4458bd DH	203	offset = nextfh & ROMFH_MASK;
da4458bd DH	204	}
da4458bd	205	out:
3903b38c	206	return 0;
da4458bd DH	207	}
	208
	209	/*
	210	* look up an entry in a directory
	211	*/
	212	static struct dentry romfs_lookup(struct inode dir, struct dentry *dentry,
00cd8dd3	213	unsigned int flags)
da4458bd DH	214	{
	215	unsigned long offset, maxoff;
	216	struct inode *inode;
	217	struct romfs_inode ri;
	218	const char name; / got from dentry */
	219	int len, ret;
	220
	221	offset = dir->i_ino & ROMFH_MASK;
	222	ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE);
	223	if (ret < 0)
	224	goto error;
	225
	226	/* search all the file entries in the list starting from the one
	227	* pointed to by the directory's special data */
	228	maxoff = romfs_maxsize(dir->i_sb);
	229	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	230
	231	name = dentry->d_name.name;
	232	len = dentry->d_name.len;
	233
	234	for (;;) {
	235	if (!offset \|\| offset >= maxoff)
	236	goto out0;
	237
	238	ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri));
	239	if (ret < 0)
	240	goto error;
	241
	242	/* try to match the first 16 bytes of name */
84baf74b DH	243	ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,
84baf74b DH	244	len);
da4458bd DH	245	if (ret < 0)
	246	goto error;
	247	if (ret == 1)
	248	break;
	249
	250	/* next entry */
	251	offset = be32_to_cpu(ri.next) & ROMFH_MASK;
	252	}
	253
	254	/* Hard link handling */
	255	if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
	256	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	257
	258	inode = romfs_iget(dir->i_sb, offset);
	259	if (IS_ERR(inode)) {
	260	ret = PTR_ERR(inode);
	261	goto error;
	262	}
	263	goto outi;
	264
	265	/*
	266	* it's a bit funky, _lookup needs to return an error code
	267	* (negative) or a NULL, both as a dentry. ENOENT should not
	268	* be returned, instead we need to create a negative dentry by
	269	* d_add(dentry, NULL); and return 0 as no error.
	270	* (Although as I see, it only matters on writable file
	271	* systems).
	272	*/
	273	out0:
	274	inode = NULL;
	275	outi:
	276	d_add(dentry, inode);
	277	ret = 0;
	278	error:
	279	return ERR_PTR(ret);
	280	}
	281
	282	static const struct file_operations romfs_dir_operations = {
	283	.read = generic_read_dir,
d375570f AV	284	.iterate_shared = romfs_readdir,
d375570f AV	285	.llseek = generic_file_llseek,
da4458bd DH	286	};
da4458bd DH	287
6e1d5dcc	288	static const struct inode_operations romfs_dir_inode_operations = {
da4458bd DH	289	.lookup = romfs_lookup,
	290	};
	291
	292	/*
	293	* get a romfs inode based on its position in the image (which doubles as the
	294	* inode number)
	295	*/
	296	static struct inode romfs_iget(struct super_block sb, unsigned long pos)
	297	{
	298	struct romfs_inode_info *inode;
	299	struct romfs_inode ri;
	300	struct inode *i;
	301	unsigned long nlen;
774e33e7 RK	302	unsigned nextfh;
774e33e7 RK	303	int ret;
da4458bd DH	304	umode_t mode;
	305
	306	/* we might have to traverse a chain of "hard link" file entries to get
	307	* to the actual file */
	308	for (;;) {
	309	ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));
	310	if (ret < 0)
	311	goto error;
	312
	313	/* XXX: do romfs_checksum here too (with name) */
	314
	315	nextfh = be32_to_cpu(ri.next);
	316	if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
	317	break;
	318
	319	pos = be32_to_cpu(ri.spec) & ROMFH_MASK;
	320	}
	321
	322	/* determine the length of the filename */
	323	nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);
	324	if (IS_ERR_VALUE(nlen))
	325	goto eio;
	326
	327	/* get an inode for this image position */
	328	i = iget_locked(sb, pos);
	329	if (!i)
	330	return ERR_PTR(-ENOMEM);
	331
	332	if (!(i->i_state & I_NEW))
	333	return i;
	334
	335	/* precalculate the data offset */
	336	inode = ROMFS_I(i);
	337	inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;
	338	inode->i_dataoffset = pos + inode->i_metasize;
	339
bfe86848	340	set_nlink(i, 1); /* Hard to decide.. */
da4458bd DH	341	i->i_size = be32_to_cpu(ri.size);
	342	i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
	343	i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0;
	344
	345	/* set up mode and ops */
	346	mode = romfs_modemap[nextfh & ROMFH_TYPE];
	347
	348	switch (nextfh & ROMFH_TYPE) {
	349	case ROMFH_DIR:
	350	i->i_size = ROMFS_I(i)->i_metasize;
	351	i->i_op = &romfs_dir_inode_operations;
	352	i->i_fop = &romfs_dir_operations;
	353	if (nextfh & ROMFH_EXEC)
	354	mode \|= S_IXUGO;
	355	break;
	356	case ROMFH_REG:
	357	i->i_fop = &romfs_ro_fops;
	358	i->i_data.a_ops = &romfs_aops;
da4458bd DH	359	if (nextfh & ROMFH_EXEC)
	360	mode \|= S_IXUGO;
	361	break;
	362	case ROMFH_SYM:
	363	i->i_op = &page_symlink_inode_operations;
21fc61c7	364	inode_nohighmem(i);
da4458bd DH	365	i->i_data.a_ops = &romfs_aops;
	366	mode \|= S_IRWXUGO;
	367	break;
	368	default:
	369	/* depending on MBZ for sock/fifos */
	370	nextfh = be32_to_cpu(ri.spec);
	371	init_special_inode(i, mode, MKDEV(nextfh >> 16,
	372	nextfh & 0xffff));
	373	break;
	374	}
	375
	376	i->i_mode = mode;
	377
	378	unlock_new_inode(i);
	379	return i;
	380
	381	eio:
	382	ret = -EIO;
	383	error:
ca9e5368	384	pr_err("read error for inode 0x%lx\n", pos);
da4458bd DH	385	return ERR_PTR(ret);
	386	}
	387
	388	/*
	389	* allocate a new inode
	390	*/
	391	static struct inode romfs_alloc_inode(struct super_block sb)
	392	{
	393	struct romfs_inode_info *inode;
b6d53b1b	394
da4458bd DH	395	inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL);
	396	return inode ? &inode->vfs_inode : NULL;
	397	}
	398
	399	/*
	400	* return a spent inode to the slab cache
	401	*/
fa0d7e3d	402	static void romfs_i_callback(struct rcu_head *head)
da4458bd	403	{
fa0d7e3d	404	struct inode *inode = container_of(head, struct inode, i_rcu);
b6d53b1b	405
da4458bd DH	406	kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
	407	}
	408
fa0d7e3d NP	409	static void romfs_destroy_inode(struct inode *inode)
	410	{
	411	call_rcu(&inode->i_rcu, romfs_i_callback);
	412	}
	413
da4458bd DH	414	/*
	415	* get filesystem statistics
	416	*/
	417	static int romfs_statfs(struct dentry dentry, struct kstatfs buf)
	418	{
8a59f5d2	419	struct super_block *sb = dentry->d_sb;
f598f82e CL	420	u64 id = 0;
	421
	422	/* When calling huge_encode_dev(),
	423	* use sb->s_bdev->bd_dev when,
	424	* - CONFIG_ROMFS_ON_BLOCK defined
	425	* use sb->s_dev when,
	426	* - CONFIG_ROMFS_ON_BLOCK undefined and
	427	* - CONFIG_ROMFS_ON_MTD defined
	428	* leave id as 0 when,
	429	* - CONFIG_ROMFS_ON_BLOCK undefined and
	430	* - CONFIG_ROMFS_ON_MTD undefined
	431	*/
	432	if (sb->s_bdev)
	433	id = huge_encode_dev(sb->s_bdev->bd_dev);
	434	else if (sb->s_dev)
	435	id = huge_encode_dev(sb->s_dev);
8a59f5d2	436
da4458bd DH	437	buf->f_type = ROMFS_MAGIC;
	438	buf->f_namelen = ROMFS_MAXFN;
	439	buf->f_bsize = ROMBSIZE;
	440	buf->f_bfree = buf->f_bavail = buf->f_ffree;
	441	buf->f_blocks =
	442	(romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;
8a59f5d2 CL	443	buf->f_fsid.val[0] = (u32)id;
8a59f5d2 CL	444	buf->f_fsid.val[1] = (u32)(id >> 32);
da4458bd DH	445	return 0;
	446	}
	447
	448	/*
	449	* remounting must involve read-only
	450	*/
	451	static int romfs_remount(struct super_block sb, int flags, char *data)
	452	{
02b9984d	453	sync_filesystem(sb);
1751e8a6	454	*flags \|= SB_RDONLY;
da4458bd DH	455	return 0;
	456	}
	457
	458	static const struct super_operations romfs_super_ops = {
	459	.alloc_inode = romfs_alloc_inode,
	460	.destroy_inode = romfs_destroy_inode,
	461	.statfs = romfs_statfs,
	462	.remount_fs = romfs_remount,
	463	};
	464
	465	/*
	466	* checksum check on part of a romfs filesystem
	467	*/
	468	static __u32 romfs_checksum(const void *data, int size)
	469	{
	470	const __be32 *ptr = data;
	471	__u32 sum;
	472
	473	sum = 0;
	474	size >>= 2;
	475	while (size > 0) {
	476	sum += be32_to_cpu(*ptr++);
	477	size--;
	478	}
	479	return sum;
	480	}
	481
	482	/*
	483	* fill in the superblock
	484	*/
	485	static int romfs_fill_super(struct super_block sb, void data, int silent)
	486	{
	487	struct romfs_super_block *rsb;
	488	struct inode *root;
	489	unsigned long pos, img_size;
	490	const char *storage;
	491	size_t len;
	492	int ret;
	493
	494	#ifdef CONFIG_BLOCK
	495	if (!sb->s_mtd) {
	496	sb_set_blocksize(sb, ROMBSIZE);
	497	} else {
	498	sb->s_blocksize = ROMBSIZE;
	499	sb->s_blocksize_bits = blksize_bits(ROMBSIZE);
	500	}
	501	#endif
	502
	503	sb->s_maxbytes = 0xFFFFFFFF;
	504	sb->s_magic = ROMFS_MAGIC;
1751e8a6	505	sb->s_flags \|= SB_RDONLY \| SB_NOATIME;
da4458bd DH	506	sb->s_op = &romfs_super_ops;
da4458bd DH	507
f598f82e CL	508	#ifdef CONFIG_ROMFS_ON_MTD
	509	/* Use same dev ID from the underlying mtdblock device */
	510	if (sb->s_mtd)
	511	sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
	512	#endif
da4458bd DH	513	/* read the image superblock and check it */
	514	rsb = kmalloc(512, GFP_KERNEL);
	515	if (!rsb)
	516	return -ENOMEM;
	517
	518	sb->s_fs_info = (void *) 512;
	519	ret = romfs_dev_read(sb, 0, rsb, 512);
	520	if (ret < 0)
	521	goto error_rsb;
	522
	523	img_size = be32_to_cpu(rsb->size);
	524
	525	if (sb->s_mtd && img_size > sb->s_mtd->size)
	526	goto error_rsb_inval;
	527
	528	sb->s_fs_info = (void *) img_size;
	529
	530	if (rsb->word0 != ROMSB_WORD0 \|\| rsb->word1 != ROMSB_WORD1 \|\|
	531	img_size < ROMFH_SIZE) {
	532	if (!silent)
3d79d314	533	pr_warn("VFS: Can't find a romfs filesystem on dev %s.\n",
da4458bd DH	534	sb->s_id);
	535	goto error_rsb_inval;
	536	}
	537
	538	if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
ca9e5368	539	pr_err("bad initial checksum on dev %s.\n", sb->s_id);
da4458bd DH	540	goto error_rsb_inval;
	541	}
	542
	543	storage = sb->s_mtd ? "MTD" : "the block layer";
	544
	545	len = strnlen(rsb->name, ROMFS_MAXFN);
	546	if (!silent)
ca9e5368 FF	547	pr_notice("Mounting image '%.s' through %s\n",
ca9e5368 FF	548	(unsigned) len, (unsigned) len, rsb->name, storage);
da4458bd DH	549
	550	kfree(rsb);
	551	rsb = NULL;
	552
	553	/* find the root directory */
	554	pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;
	555
	556	root = romfs_iget(sb, pos);
a21f3c2a	557	if (IS_ERR(root))
40e2c71d	558	return PTR_ERR(root);
da4458bd	559
48fde701	560	sb->s_root = d_make_root(root);
da4458bd	561	if (!sb->s_root)
40e2c71d	562	return -ENOMEM;
da4458bd DH	563
	564	return 0;
	565
da4458bd DH	566	error_rsb_inval:
	567	ret = -EINVAL;
	568	error_rsb:
7e32b7bb	569	kfree(rsb);
da4458bd DH	570	return ret;
	571	}
	572
	573	/*
	574	* get a superblock for mounting
	575	*/
848b83a5	576	static struct dentry romfs_mount(struct file_system_type fs_type,
da4458bd	577	int flags, const char *dev_name,
848b83a5	578	void *data)
da4458bd	579	{
848b83a5	580	struct dentry *ret = ERR_PTR(-EINVAL);
da4458bd DH	581
da4458bd DH	582	#ifdef CONFIG_ROMFS_ON_MTD
848b83a5	583	ret = mount_mtd(fs_type, flags, dev_name, data, romfs_fill_super);
da4458bd DH	584	#endif
da4458bd DH	585	#ifdef CONFIG_ROMFS_ON_BLOCK
848b83a5 AV	586	if (ret == ERR_PTR(-EINVAL))
	587	ret = mount_bdev(fs_type, flags, dev_name, data,
	588	romfs_fill_super);
da4458bd DH	589	#endif
	590	return ret;
	591	}
	592
	593	/*
	594	* destroy a romfs superblock in the appropriate manner
	595	*/
	596	static void romfs_kill_sb(struct super_block *sb)
	597	{
	598	#ifdef CONFIG_ROMFS_ON_MTD
	599	if (sb->s_mtd) {
	600	kill_mtd_super(sb);
	601	return;
	602	}
	603	#endif
	604	#ifdef CONFIG_ROMFS_ON_BLOCK
	605	if (sb->s_bdev) {
	606	kill_block_super(sb);
	607	return;
	608	}
	609	#endif
	610	}
	611
	612	static struct file_system_type romfs_fs_type = {
	613	.owner = THIS_MODULE,
	614	.name = "romfs",
848b83a5	615	.mount = romfs_mount,
da4458bd DH	616	.kill_sb = romfs_kill_sb,
	617	.fs_flags = FS_REQUIRES_DEV,
	618	};
7f78e035	619	MODULE_ALIAS_FS("romfs");
da4458bd DH	620
	621	/*
	622	* inode storage initialiser
	623	*/
	624	static void romfs_i_init_once(void *_inode)
	625	{
	626	struct romfs_inode_info *inode = _inode;
	627
	628	inode_init_once(&inode->vfs_inode);
	629	}
	630
	631	/*
	632	* romfs module initialisation
	633	*/
	634	static int __init init_romfs_fs(void)
	635	{
	636	int ret;
	637
3d79d314	638	pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n");
da4458bd DH	639
	640	romfs_inode_cachep =
	641	kmem_cache_create("romfs_i",
	642	sizeof(struct romfs_inode_info), 0,
5d097056 VD	643	SLAB_RECLAIM_ACCOUNT \| SLAB_MEM_SPREAD \|
5d097056 VD	644	SLAB_ACCOUNT, romfs_i_init_once);
da4458bd DH	645
da4458bd DH	646	if (!romfs_inode_cachep) {
ca9e5368	647	pr_err("Failed to initialise inode cache\n");
da4458bd DH	648	return -ENOMEM;
	649	}
	650	ret = register_filesystem(&romfs_fs_type);
	651	if (ret) {
ca9e5368	652	pr_err("Failed to register filesystem\n");
da4458bd DH	653	goto error_register;
	654	}
	655	return 0;
	656
	657	error_register:
	658	kmem_cache_destroy(romfs_inode_cachep);
	659	return ret;
	660	}
	661
	662	/*
	663	* romfs module removal
	664	*/
	665	static void __exit exit_romfs_fs(void)
	666	{
	667	unregister_filesystem(&romfs_fs_type);
8c0a8537 KS	668	/*
	669	* Make sure all delayed rcu free inodes are flushed before we
	670	* destroy cache.
	671	*/
	672	rcu_barrier();
da4458bd DH	673	kmem_cache_destroy(romfs_inode_cachep);
	674	}
	675
	676	module_init(init_romfs_fs);
	677	module_exit(exit_romfs_fs);
	678
	679	MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
	680	MODULE_AUTHOR("Red Hat, Inc.");
	681	MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */