[linux.git] / fs / romfs / super.c

/* Block- or MTD-based romfs
 *
 * Copyright © 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * Derived from: ROMFS file system, Linux implementation
 *
 * Copyright © 1997-1999  Janos Farkas <[email protected]>
 *
 * 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 read_folio
 *					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 read_folio
 *					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/fs_context.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_read_folio(struct file *file, struct folio *folio)
{
	struct page *page = &folio->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 = {
	.read_folio	= romfs_read_folio
};

/*
 * 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 = NULL;
	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)
			break;

		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) {
			/* 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);
			break;
		}

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

	return d_splice_alias(inode, dentry);
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);
	inode_set_mtime_to_ts(i,
			      inode_set_atime_to_ts(i, inode_set_ctime(i, 0, 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;
	i->i_blocks = (i->i_size + 511) >> 9;

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

/*
 * return a spent inode to the slab cache
 */
static void romfs_free_inode(struct inode *inode)
{
	kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
}

/*
 * 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 = u64_to_fsid(id);
	return 0;
}

/*
 * remounting must involve read-only
 */
static int romfs_reconfigure(struct fs_context *fc)
{
	sync_filesystem(fc->root->d_sb);
	fc->sb_flags |= SB_RDONLY;
	return 0;
}

static const struct super_operations romfs_super_ops = {
	.alloc_inode	= romfs_alloc_inode,
	.free_inode	= romfs_free_inode,
	.statfs		= romfs_statfs,
};

/*
 * 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, struct fs_context *fc)
{
	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_time_min = 0;
	sb->s_time_max = 0;
	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 (!(fc->sb_flags & SB_SILENT))
			errorf(fc, "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 (!(fc->sb_flags & SB_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 int romfs_get_tree(struct fs_context *fc)
{
	int ret = -EINVAL;

#ifdef CONFIG_ROMFS_ON_MTD
	ret = get_tree_mtd(fc, romfs_fill_super);
#endif
#ifdef CONFIG_ROMFS_ON_BLOCK
	if (ret == -EINVAL)
		ret = get_tree_bdev(fc, romfs_fill_super);
#endif
	return ret;
}

static const struct fs_context_operations romfs_context_ops = {
	.get_tree	= romfs_get_tree,
	.reconfigure	= romfs_reconfigure,
};

/*
 * Set up the filesystem mount context.
 */
static int romfs_init_fs_context(struct fs_context *fc)
{
	fc->ops = &romfs_context_ops;
	return 0;
}

/*
 * destroy a romfs superblock in the appropriate manner
 */
static void romfs_kill_sb(struct super_block *sb)
{
	generic_shutdown_super(sb);

#ifdef CONFIG_ROMFS_ON_MTD
	if (sb->s_mtd) {
		put_mtd_device(sb->s_mtd);
		sb->s_mtd = NULL;
	}
#endif
#ifdef CONFIG_ROMFS_ON_BLOCK
	if (sb->s_bdev) {
		sync_blockdev(sb->s_bdev);
		bdev_release(sb->s_bdev_handle);
	}
#endif
}

static struct file_system_type romfs_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "romfs",
	.init_fs_context = romfs_init_fs_context,
	.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 ([email protected])
	5	*
	6	* Derived from: ROMFS file system, Linux implementation
	7	*
	8	* Copyright © 1997-1999 Janos Farkas <[email protected]>
	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
f91dbd02	21	* Proper page locking in read_folio
da4458bd DH	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
f91dbd02	44	* in read_folio
da4458bd DH	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>
b9417599	68	#include <linux/fs_context.h>
da4458bd DH	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	*/
f91dbd02	102	static int romfs_read_folio(struct file file, struct folio folio)
da4458bd	103	{
f91dbd02	104	struct page *page = &folio->page;
da4458bd DH	105	struct inode *inode = page->mapping->host;
	106	loff_t offset, size;
	107	unsigned long fillsize, pos;
	108	void *buf;
	109	int ret;
	110
	111	buf = kmap(page);
	112	if (!buf)
	113	return -ENOMEM;
	114
	115	/* 32 bit warning -- but not for us :) */
	116	offset = page_offset(page);
	117	size = i_size_read(inode);
	118	fillsize = 0;
	119	ret = 0;
	120	if (offset < size) {
	121	size -= offset;
	122	fillsize = size > PAGE_SIZE ? PAGE_SIZE : size;
	123
	124	pos = ROMFS_I(inode)->i_dataoffset + offset;
	125
	126	ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize);
	127	if (ret < 0) {
	128	SetPageError(page);
	129	fillsize = 0;
	130	ret = -EIO;
	131	}
	132	}
	133
	134	if (fillsize < PAGE_SIZE)
	135	memset(buf + fillsize, 0, PAGE_SIZE - fillsize);
	136	if (ret == 0)
	137	SetPageUptodate(page);
	138
	139	flush_dcache_page(page);
	140	kunmap(page);
	141	unlock_page(page);
	142	return ret;
	143	}
	144
	145	static const struct address_space_operations romfs_aops = {
f91dbd02	146	.read_folio = romfs_read_folio
da4458bd DH	147	};
	148
	149	/*
	150	* read the entries from a directory
	151	*/
3903b38c	152	static int romfs_readdir(struct file file, struct dir_context ctx)
da4458bd	153	{
3903b38c	154	struct inode *i = file_inode(file);
da4458bd DH	155	struct romfs_inode ri;
	156	unsigned long offset, maxoff;
	157	int j, ino, nextfh;
da4458bd DH	158	char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
	159	int ret;
	160
	161	maxoff = romfs_maxsize(i->i_sb);
	162
3903b38c	163	offset = ctx->pos;
da4458bd DH	164	if (!offset) {
	165	offset = i->i_ino & ROMFH_MASK;
	166	ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
	167	if (ret < 0)
	168	goto out;
	169	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	170	}
	171
	172	/* Not really failsafe, but we are read-only... */
	173	for (;;) {
	174	if (!offset \|\| offset >= maxoff) {
	175	offset = maxoff;
3903b38c	176	ctx->pos = offset;
da4458bd DH	177	goto out;
da4458bd DH	178	}
3903b38c	179	ctx->pos = offset;
da4458bd DH	180
	181	/* Fetch inode info */
	182	ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
	183	if (ret < 0)
	184	goto out;
	185
	186	j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE,
	187	sizeof(fsname) - 1);
	188	if (j < 0)
	189	goto out;
	190
	191	ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j);
	192	if (ret < 0)
	193	goto out;
	194	fsname[j] = '\0';
	195
	196	ino = offset;
	197	nextfh = be32_to_cpu(ri.next);
	198	if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
	199	ino = be32_to_cpu(ri.spec);
3903b38c AV	200	if (!dir_emit(ctx, fsname, j, ino,
3903b38c AV	201	romfs_dtype_table[nextfh & ROMFH_TYPE]))
da4458bd DH	202	goto out;
da4458bd DH	203
da4458bd DH	204	offset = nextfh & ROMFH_MASK;
da4458bd DH	205	}
da4458bd	206	out:
3903b38c	207	return 0;
da4458bd DH	208	}
	209
	210	/*
	211	* look up an entry in a directory
	212	*/
	213	static struct dentry romfs_lookup(struct inode dir, struct dentry *dentry,
00cd8dd3	214	unsigned int flags)
da4458bd DH	215	{
da4458bd DH	216	unsigned long offset, maxoff;
8130c151	217	struct inode *inode = NULL;
da4458bd DH	218	struct romfs_inode ri;
	219	const char name; / got from dentry */
	220	int len, ret;
	221
	222	offset = dir->i_ino & ROMFH_MASK;
	223	ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE);
	224	if (ret < 0)
	225	goto error;
	226
	227	/* search all the file entries in the list starting from the one
	228	* pointed to by the directory's special data */
	229	maxoff = romfs_maxsize(dir->i_sb);
	230	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	231
	232	name = dentry->d_name.name;
	233	len = dentry->d_name.len;
	234
	235	for (;;) {
	236	if (!offset \|\| offset >= maxoff)
8130c151	237	break;
da4458bd DH	238
	239	ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri));
	240	if (ret < 0)
	241	goto error;
	242
	243	/* try to match the first 16 bytes of name */
84baf74b DH	244	ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,
84baf74b DH	245	len);
da4458bd DH	246	if (ret < 0)
da4458bd DH	247	goto error;
8130c151 AV	248	if (ret == 1) {
	249	/* Hard link handling */
	250	if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
	251	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
	252	inode = romfs_iget(dir->i_sb, offset);
da4458bd	253	break;
8130c151	254	}
da4458bd DH	255
	256	/* next entry */
	257	offset = be32_to_cpu(ri.next) & ROMFH_MASK;
	258	}
	259
8130c151	260	return d_splice_alias(inode, dentry);
da4458bd DH	261	error:
	262	return ERR_PTR(ret);
	263	}
	264
	265	static const struct file_operations romfs_dir_operations = {
	266	.read = generic_read_dir,
d375570f AV	267	.iterate_shared = romfs_readdir,
d375570f AV	268	.llseek = generic_file_llseek,
da4458bd DH	269	};
da4458bd DH	270
6e1d5dcc	271	static const struct inode_operations romfs_dir_inode_operations = {
da4458bd DH	272	.lookup = romfs_lookup,
	273	};
	274
	275	/*
	276	* get a romfs inode based on its position in the image (which doubles as the
	277	* inode number)
	278	*/
	279	static struct inode romfs_iget(struct super_block sb, unsigned long pos)
	280	{
	281	struct romfs_inode_info *inode;
	282	struct romfs_inode ri;
	283	struct inode *i;
	284	unsigned long nlen;
774e33e7 RK	285	unsigned nextfh;
774e33e7 RK	286	int ret;
da4458bd DH	287	umode_t mode;
	288
	289	/* we might have to traverse a chain of "hard link" file entries to get
	290	* to the actual file */
	291	for (;;) {
	292	ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));
	293	if (ret < 0)
	294	goto error;
	295
	296	/* XXX: do romfs_checksum here too (with name) */
	297
	298	nextfh = be32_to_cpu(ri.next);
	299	if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
	300	break;
	301
	302	pos = be32_to_cpu(ri.spec) & ROMFH_MASK;
	303	}
	304
	305	/* determine the length of the filename */
	306	nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);
	307	if (IS_ERR_VALUE(nlen))
	308	goto eio;
	309
	310	/* get an inode for this image position */
	311	i = iget_locked(sb, pos);
	312	if (!i)
	313	return ERR_PTR(-ENOMEM);
	314
	315	if (!(i->i_state & I_NEW))
	316	return i;
	317
	318	/* precalculate the data offset */
	319	inode = ROMFS_I(i);
	320	inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;
	321	inode->i_dataoffset = pos + inode->i_metasize;
	322
bfe86848	323	set_nlink(i, 1); /* Hard to decide.. */
da4458bd	324	i->i_size = be32_to_cpu(ri.size);
f26c93d3 JL	325	inode_set_mtime_to_ts(i,
f26c93d3 JL	326	inode_set_atime_to_ts(i, inode_set_ctime(i, 0, 0)));
da4458bd DH	327
	328	/* set up mode and ops */
	329	mode = romfs_modemap[nextfh & ROMFH_TYPE];
	330
	331	switch (nextfh & ROMFH_TYPE) {
	332	case ROMFH_DIR:
	333	i->i_size = ROMFS_I(i)->i_metasize;
	334	i->i_op = &romfs_dir_inode_operations;
	335	i->i_fop = &romfs_dir_operations;
	336	if (nextfh & ROMFH_EXEC)
	337	mode \|= S_IXUGO;
	338	break;
	339	case ROMFH_REG:
	340	i->i_fop = &romfs_ro_fops;
	341	i->i_data.a_ops = &romfs_aops;
da4458bd DH	342	if (nextfh & ROMFH_EXEC)
	343	mode \|= S_IXUGO;
	344	break;
	345	case ROMFH_SYM:
	346	i->i_op = &page_symlink_inode_operations;
21fc61c7	347	inode_nohighmem(i);
da4458bd DH	348	i->i_data.a_ops = &romfs_aops;
	349	mode \|= S_IRWXUGO;
	350	break;
	351	default:
	352	/* depending on MBZ for sock/fifos */
	353	nextfh = be32_to_cpu(ri.spec);
	354	init_special_inode(i, mode, MKDEV(nextfh >> 16,
	355	nextfh & 0xffff));
	356	break;
	357	}
	358
	359	i->i_mode = mode;
d9bc85de	360	i->i_blocks = (i->i_size + 511) >> 9;
da4458bd DH	361
	362	unlock_new_inode(i);
	363	return i;
	364
	365	eio:
	366	ret = -EIO;
	367	error:
ca9e5368	368	pr_err("read error for inode 0x%lx\n", pos);
da4458bd DH	369	return ERR_PTR(ret);
	370	}
	371
	372	/*
	373	* allocate a new inode
	374	*/
	375	static struct inode romfs_alloc_inode(struct super_block sb)
	376	{
	377	struct romfs_inode_info *inode;
b6d53b1b	378
fd60b288	379	inode = alloc_inode_sb(sb, romfs_inode_cachep, GFP_KERNEL);
da4458bd DH	380	return inode ? &inode->vfs_inode : NULL;
	381	}
	382
	383	/*
	384	* return a spent inode to the slab cache
	385	*/
bcb8d71b	386	static void romfs_free_inode(struct inode *inode)
da4458bd DH	387	{
	388	kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
	389	}
	390
	391	/*
	392	* get filesystem statistics
	393	*/
	394	static int romfs_statfs(struct dentry dentry, struct kstatfs buf)
	395	{
8a59f5d2	396	struct super_block *sb = dentry->d_sb;
f598f82e CL	397	u64 id = 0;
	398
	399	/* When calling huge_encode_dev(),
	400	* use sb->s_bdev->bd_dev when,
	401	* - CONFIG_ROMFS_ON_BLOCK defined
	402	* use sb->s_dev when,
	403	* - CONFIG_ROMFS_ON_BLOCK undefined and
	404	* - CONFIG_ROMFS_ON_MTD defined
	405	* leave id as 0 when,
	406	* - CONFIG_ROMFS_ON_BLOCK undefined and
	407	* - CONFIG_ROMFS_ON_MTD undefined
	408	*/
	409	if (sb->s_bdev)
	410	id = huge_encode_dev(sb->s_bdev->bd_dev);
	411	else if (sb->s_dev)
	412	id = huge_encode_dev(sb->s_dev);
8a59f5d2	413
da4458bd DH	414	buf->f_type = ROMFS_MAGIC;
	415	buf->f_namelen = ROMFS_MAXFN;
	416	buf->f_bsize = ROMBSIZE;
	417	buf->f_bfree = buf->f_bavail = buf->f_ffree;
	418	buf->f_blocks =
	419	(romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;
6d1349c7	420	buf->f_fsid = u64_to_fsid(id);
da4458bd DH	421	return 0;
	422	}
	423
	424	/*
	425	* remounting must involve read-only
	426	*/
b9417599	427	static int romfs_reconfigure(struct fs_context *fc)
da4458bd	428	{
b9417599 DH	429	sync_filesystem(fc->root->d_sb);
b9417599 DH	430	fc->sb_flags \|= SB_RDONLY;
da4458bd DH	431	return 0;
	432	}
	433
	434	static const struct super_operations romfs_super_ops = {
	435	.alloc_inode = romfs_alloc_inode,
bcb8d71b	436	.free_inode = romfs_free_inode,
da4458bd	437	.statfs = romfs_statfs,
da4458bd DH	438	};
	439
	440	/*
	441	* checksum check on part of a romfs filesystem
	442	*/
	443	static __u32 romfs_checksum(const void *data, int size)
	444	{
	445	const __be32 *ptr = data;
	446	__u32 sum;
	447
	448	sum = 0;
	449	size >>= 2;
	450	while (size > 0) {
	451	sum += be32_to_cpu(*ptr++);
	452	size--;
	453	}
	454	return sum;
	455	}
	456
	457	/*
	458	* fill in the superblock
	459	*/
b9417599	460	static int romfs_fill_super(struct super_block sb, struct fs_context fc)
da4458bd DH	461	{
	462	struct romfs_super_block *rsb;
	463	struct inode *root;
	464	unsigned long pos, img_size;
	465	const char *storage;
	466	size_t len;
	467	int ret;
	468
	469	#ifdef CONFIG_BLOCK
	470	if (!sb->s_mtd) {
	471	sb_set_blocksize(sb, ROMBSIZE);
	472	} else {
	473	sb->s_blocksize = ROMBSIZE;
	474	sb->s_blocksize_bits = blksize_bits(ROMBSIZE);
	475	}
	476	#endif
	477
	478	sb->s_maxbytes = 0xFFFFFFFF;
	479	sb->s_magic = ROMFS_MAGIC;
1751e8a6	480	sb->s_flags \|= SB_RDONLY \| SB_NOATIME;
22b13969 DD	481	sb->s_time_min = 0;
22b13969 DD	482	sb->s_time_max = 0;
da4458bd DH	483	sb->s_op = &romfs_super_ops;
da4458bd DH	484
f598f82e CL	485	#ifdef CONFIG_ROMFS_ON_MTD
	486	/* Use same dev ID from the underlying mtdblock device */
	487	if (sb->s_mtd)
	488	sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
	489	#endif
da4458bd DH	490	/* read the image superblock and check it */
	491	rsb = kmalloc(512, GFP_KERNEL);
	492	if (!rsb)
	493	return -ENOMEM;
	494
	495	sb->s_fs_info = (void *) 512;
	496	ret = romfs_dev_read(sb, 0, rsb, 512);
	497	if (ret < 0)
	498	goto error_rsb;
	499
	500	img_size = be32_to_cpu(rsb->size);
	501
	502	if (sb->s_mtd && img_size > sb->s_mtd->size)
	503	goto error_rsb_inval;
	504
	505	sb->s_fs_info = (void *) img_size;
	506
	507	if (rsb->word0 != ROMSB_WORD0 \|\| rsb->word1 != ROMSB_WORD1 \|\|
	508	img_size < ROMFH_SIZE) {
b9417599 DH	509	if (!(fc->sb_flags & SB_SILENT))
b9417599 DH	510	errorf(fc, "VFS: Can't find a romfs filesystem on dev %s.\n",
da4458bd DH	511	sb->s_id);
	512	goto error_rsb_inval;
	513	}
	514
	515	if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
ca9e5368	516	pr_err("bad initial checksum on dev %s.\n", sb->s_id);
da4458bd DH	517	goto error_rsb_inval;
	518	}
	519
	520	storage = sb->s_mtd ? "MTD" : "the block layer";
	521
	522	len = strnlen(rsb->name, ROMFS_MAXFN);
b9417599	523	if (!(fc->sb_flags & SB_SILENT))
ca9e5368 FF	524	pr_notice("Mounting image '%.s' through %s\n",
ca9e5368 FF	525	(unsigned) len, (unsigned) len, rsb->name, storage);
da4458bd DH	526
	527	kfree(rsb);
	528	rsb = NULL;
	529
	530	/* find the root directory */
	531	pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;
	532
	533	root = romfs_iget(sb, pos);
a21f3c2a	534	if (IS_ERR(root))
40e2c71d	535	return PTR_ERR(root);
da4458bd	536
48fde701	537	sb->s_root = d_make_root(root);
da4458bd	538	if (!sb->s_root)
40e2c71d	539	return -ENOMEM;
da4458bd DH	540
	541	return 0;
	542
da4458bd DH	543	error_rsb_inval:
	544	ret = -EINVAL;
	545	error_rsb:
7e32b7bb	546	kfree(rsb);
da4458bd DH	547	return ret;
	548	}
	549
	550	/*
	551	* get a superblock for mounting
	552	*/
b9417599	553	static int romfs_get_tree(struct fs_context *fc)
da4458bd	554	{
b9417599	555	int ret = -EINVAL;
da4458bd DH	556
da4458bd DH	557	#ifdef CONFIG_ROMFS_ON_MTD
b9417599	558	ret = get_tree_mtd(fc, romfs_fill_super);
da4458bd DH	559	#endif
da4458bd DH	560	#ifdef CONFIG_ROMFS_ON_BLOCK
b9417599 DH	561	if (ret == -EINVAL)
b9417599 DH	562	ret = get_tree_bdev(fc, romfs_fill_super);
da4458bd DH	563	#endif
	564	return ret;
	565	}
	566
b9417599 DH	567	static const struct fs_context_operations romfs_context_ops = {
	568	.get_tree = romfs_get_tree,
	569	.reconfigure = romfs_reconfigure,
	570	};
	571
	572	/*
	573	* Set up the filesystem mount context.
	574	*/
	575	static int romfs_init_fs_context(struct fs_context *fc)
	576	{
	577	fc->ops = &romfs_context_ops;
	578	return 0;
	579	}
	580
da4458bd DH	581	/*
	582	* destroy a romfs superblock in the appropriate manner
	583	*/
	584	static void romfs_kill_sb(struct super_block *sb)
	585	{
aca740ce JK	586	generic_shutdown_super(sb);
aca740ce JK	587
da4458bd DH	588	#ifdef CONFIG_ROMFS_ON_MTD
da4458bd DH	589	if (sb->s_mtd) {
aca740ce JK	590	put_mtd_device(sb->s_mtd);
aca740ce JK	591	sb->s_mtd = NULL;
da4458bd DH	592	}
	593	#endif
	594	#ifdef CONFIG_ROMFS_ON_BLOCK
	595	if (sb->s_bdev) {
aca740ce	596	sync_blockdev(sb->s_bdev);
f4a48bc3	597	bdev_release(sb->s_bdev_handle);
da4458bd DH	598	}
	599	#endif
	600	}
	601
	602	static struct file_system_type romfs_fs_type = {
	603	.owner = THIS_MODULE,
	604	.name = "romfs",
b9417599	605	.init_fs_context = romfs_init_fs_context,
da4458bd DH	606	.kill_sb = romfs_kill_sb,
	607	.fs_flags = FS_REQUIRES_DEV,
	608	};
7f78e035	609	MODULE_ALIAS_FS("romfs");
da4458bd DH	610
	611	/*
	612	* inode storage initialiser
	613	*/
	614	static void romfs_i_init_once(void *_inode)
	615	{
	616	struct romfs_inode_info *inode = _inode;
	617
	618	inode_init_once(&inode->vfs_inode);
	619	}
	620
	621	/*
	622	* romfs module initialisation
	623	*/
	624	static int __init init_romfs_fs(void)
	625	{
	626	int ret;
	627
3d79d314	628	pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n");
da4458bd DH	629
	630	romfs_inode_cachep =
	631	kmem_cache_create("romfs_i",
	632	sizeof(struct romfs_inode_info), 0,
5d097056 VD	633	SLAB_RECLAIM_ACCOUNT \| SLAB_MEM_SPREAD \|
5d097056 VD	634	SLAB_ACCOUNT, romfs_i_init_once);
da4458bd DH	635
da4458bd DH	636	if (!romfs_inode_cachep) {
ca9e5368	637	pr_err("Failed to initialise inode cache\n");
da4458bd DH	638	return -ENOMEM;
	639	}
	640	ret = register_filesystem(&romfs_fs_type);
	641	if (ret) {
ca9e5368	642	pr_err("Failed to register filesystem\n");
da4458bd DH	643	goto error_register;
	644	}
	645	return 0;
	646
	647	error_register:
	648	kmem_cache_destroy(romfs_inode_cachep);
	649	return ret;
	650	}
	651
	652	/*
	653	* romfs module removal
	654	*/
	655	static void __exit exit_romfs_fs(void)
	656	{
	657	unregister_filesystem(&romfs_fs_type);
8c0a8537 KS	658	/*
	659	* Make sure all delayed rcu free inodes are flushed before we
	660	* destroy cache.
	661	*/
	662	rcu_barrier();
da4458bd DH	663	kmem_cache_destroy(romfs_inode_cachep);
	664	}
	665
	666	module_init(init_romfs_fs);
	667	module_exit(exit_romfs_fs);
	668
	669	MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
	670	MODULE_AUTHOR("Red Hat, Inc.");
	671	MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */