NOMMU: Make it possible for RomFS to use MTD devices directly

Change RomFS so that it can use MTD devices directly - without the intercession
of the block layer - as well as using block devices.

This permits RomFS:

 (1) to use the MTD direct mapping facility available under NOMMU conditions if
     the underlying device is directly accessible by the CPU (including XIP);

 (2) and thus to be used when the block layer is disabled.

RomFS can be configured with support just for MTD devices, just for Block
devices or for both.  If RomFS is configured for both, then it will treat
mtdblock device files as MTD backing stores, not block layer backing stores.

I tested this using a CONFIG_MMU=n CONFIG_BLOCK=n kernel running on my FRV
board with a RomFS image installed on the mtdram test device.  I see my test
program being run XIP:

	# cat /proc/maps
	...
	c0c000b0-c0c01f8c r-xs 00000000 1f:00 144        /mnt/doshm
	...

GDB on the kernel can be used to show that these addresses are within the
set-aside RAM space.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Bernd Schmidt <bernd.schmidt@analog.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 0 insertions, 665 deletions

diff --git a/fs/romfs/inode.c b/fs/romfs/inode.c
deleted file mode 100644
index 98a232f7196..00000000000
--- a/fs/romfs/inode.c
+++ /dev/null
@@ -1,665 +0,0 @@
-/*
- * ROMFS file system, Linux implementation
- *
- * Copyright (C) 1997-1999  Janos Farkas <chexum@shadow.banki.hu>
- *
- * Using parts of the minix filesystem
- * Copyright (C) 1991, 1992  Linus Torvalds
- *
- * and parts of the affs filesystem additionally
- * Copyright (C) 1993  Ray Burr
- * Copyright (C) 1996  Hans-Joachim Widmaier
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- *
- * 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
- */
-
-/* todo:
- *	- see Documentation/filesystems/romfs.txt
- *	- use allocated, not stack memory for file names?
- *	- considering write access...
- *	- network (tftp) files?
- *	- merge back some _op tables
- */
-
-/*
- * Sorry about some optimizations and for some goto's.  I just wanted
- * to squeeze some more bytes out of this code.. :)
- */
-
-#include <linux/module.h>
-#include <linux/types.h>
-#include <linux/errno.h>
-#include <linux/slab.h>
-#include <linux/romfs_fs.h>
-#include <linux/fs.h>
-#include <linux/init.h>
-#include <linux/pagemap.h>
-#include <linux/smp_lock.h>
-#include <linux/buffer_head.h>
-#include <linux/vfs.h>
-
-#include <asm/uaccess.h>
-
-struct romfs_inode_info {
-	unsigned long i_metasize;	/* size of non-data area */
-	unsigned long i_dataoffset;	/* from the start of fs */
-	struct inode vfs_inode;
-};
-
-static struct inode *romfs_iget(struct super_block *, unsigned long);
-
-/* instead of private superblock data */
-static inline unsigned long romfs_maxsize(struct super_block *sb)
-{
-	return (unsigned long)sb->s_fs_info;
-}
-
-static inline struct romfs_inode_info *ROMFS_I(struct inode *inode)
-{
-	return container_of(inode, struct romfs_inode_info, vfs_inode);
-}
-
-static __u32
-romfs_checksum(void *data, int size)
-{
-	__u32 sum;
-	__be32 *ptr;
-
-	sum = 0; ptr = data;
-	size>>=2;
-	while (size>0) {
-		sum += be32_to_cpu(*ptr++);
-		size--;
-	}
-	return sum;
-}
-
-static const struct super_operations romfs_ops;
-
-static int romfs_fill_super(struct super_block *s, void *data, int silent)
-{
-	struct buffer_head *bh;
-	struct romfs_super_block *rsb;
-	struct inode *root;
-	int sz, ret = -EINVAL;
-
-	/* I would parse the options here, but there are none.. :) */
-
-	sb_set_blocksize(s, ROMBSIZE);
-	s->s_maxbytes = 0xFFFFFFFF;
-
-	bh = sb_bread(s, 0);
-	if (!bh) {
-		/* XXX merge with other printk? */
-                printk ("romfs: unable to read superblock\n");
-		goto outnobh;
-	}
-
-	rsb = (struct romfs_super_block *)bh->b_data;
-	sz = be32_to_cpu(rsb->size);
-	if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1
-	   || sz < ROMFH_SIZE) {
-		if (!silent)
-			printk ("VFS: Can't find a romfs filesystem on dev "
-				"%s.\n", s->s_id);
-		goto out;
-	}
-	if (romfs_checksum(rsb, min_t(int, sz, 512))) {
-		printk ("romfs: bad initial checksum on dev "
-			"%s.\n", s->s_id);
-		goto out;
-	}
-
-	s->s_magic = ROMFS_MAGIC;
-	s->s_fs_info = (void *)(long)sz;
-
-	s->s_flags |= MS_RDONLY;
-
-	/* Find the start of the fs */
-	sz = (ROMFH_SIZE +
-	      strnlen(rsb->name, ROMFS_MAXFN) + 1 + ROMFH_PAD)
-	     & ROMFH_MASK;
-
-	s->s_op	= &romfs_ops;
-	root = romfs_iget(s, sz);
-	if (IS_ERR(root)) {
-		ret = PTR_ERR(root);
-		goto out;
-	}
-
-	ret = -ENOMEM;
-	s->s_root = d_alloc_root(root);
-	if (!s->s_root)
-		goto outiput;
-
-	brelse(bh);
-	return 0;
-
-outiput:
-	iput(root);
-out:
-	brelse(bh);
-outnobh:
-	return ret;
-}
-
-/* That's simple too. */
-
-static int
-romfs_statfs(struct dentry *dentry, struct kstatfs *buf)
-{
-	buf->f_type = ROMFS_MAGIC;
-	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_namelen = ROMFS_MAXFN;
-	return 0;
-}
-
-/* some helper routines */
-
-static int
-romfs_strnlen(struct inode *i, unsigned long offset, unsigned long count)
-{
-	struct buffer_head *bh;
-	unsigned long avail, maxsize, res;
-
-	maxsize = romfs_maxsize(i->i_sb);
-	if (offset >= maxsize)
-		return -1;
-
-	/* strnlen is almost always valid */
-	if (count > maxsize || offset+count > maxsize)
-		count = maxsize-offset;
-
-	bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
-	if (!bh)
-		return -1;		/* error */
-
-	avail = ROMBSIZE - (offset & ROMBMASK);
-	maxsize = min_t(unsigned long, count, avail);
-	res = strnlen(((char *)bh->b_data)+(offset&ROMBMASK), maxsize);
-	brelse(bh);
-
-	if (res < maxsize)
-		return res;		/* found all of it */
-
-	while (res < count) {
-		offset += maxsize;
-
-		bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
-		if (!bh)
-			return -1;
-		maxsize = min_t(unsigned long, count - res, ROMBSIZE);
-		avail = strnlen(bh->b_data, maxsize);
-		res += avail;
-		brelse(bh);
-		if (avail < maxsize)
-			return res;
-	}
-	return res;
-}
-
-static int
-romfs_copyfrom(struct inode *i, void *dest, unsigned long offset, unsigned long count)
-{
-	struct buffer_head *bh;
-	unsigned long avail, maxsize, res;
-
-	maxsize = romfs_maxsize(i->i_sb);
-	if (offset >= maxsize || count > maxsize || offset+count>maxsize)
-		return -1;
-
-	bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
-	if (!bh)
-		return -1;		/* error */
-
-	avail = ROMBSIZE - (offset & ROMBMASK);
-	maxsize = min_t(unsigned long, count, avail);
-	memcpy(dest, ((char *)bh->b_data) + (offset & ROMBMASK), maxsize);
-	brelse(bh);
-
-	res = maxsize;			/* all of it */
-
-	while (res < count) {
-		offset += maxsize;
-		dest += maxsize;
-
-		bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
-		if (!bh)
-			return -1;
-		maxsize = min_t(unsigned long, count - res, ROMBSIZE);
-		memcpy(dest, bh->b_data, maxsize);
-		brelse(bh);
-		res += maxsize;
-	}
-	return res;
-}
-
-static unsigned char romfs_dtype_table[] = {
-	DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
-};
-
-static int
-romfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
-{
-	struct inode *i = filp->f_path.dentry->d_inode;
-	struct romfs_inode ri;
-	unsigned long offset, maxoff;
-	int j, ino, nextfh;
-	int stored = 0;
-	char fsname[ROMFS_MAXFN];	/* XXX dynamic? */
-
-	lock_kernel();
-
-	maxoff = romfs_maxsize(i->i_sb);
-
-	offset = filp->f_pos;
-	if (!offset) {
-		offset = i->i_ino & ROMFH_MASK;
-		if (romfs_copyfrom(i, &ri, offset, ROMFH_SIZE) <= 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;
-			filp->f_pos = offset;
-			goto out;
-		}
-		filp->f_pos = offset;
-
-		/* Fetch inode info */
-		if (romfs_copyfrom(i, &ri, offset, ROMFH_SIZE) <= 0)
-			goto out;
-
-		j = romfs_strnlen(i, offset+ROMFH_SIZE, sizeof(fsname)-1);
-		if (j < 0)
-			goto out;
-
-		fsname[j]=0;
-		romfs_copyfrom(i, fsname, offset+ROMFH_SIZE, j);
-
-		ino = offset;
-		nextfh = be32_to_cpu(ri.next);
-		if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
-			ino = be32_to_cpu(ri.spec);
-		if (filldir(dirent, fsname, j, offset, ino,
-			    romfs_dtype_table[nextfh & ROMFH_TYPE]) < 0) {
-			goto out;
-		}
-		stored++;
-		offset = nextfh & ROMFH_MASK;
-	}
-out:
-	unlock_kernel();
-	return stored;
-}
-
-static struct dentry *
-romfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
-{
-	unsigned long offset, maxoff;
-	long res;
-	int fslen;
-	struct inode *inode = NULL;
-	char fsname[ROMFS_MAXFN];	/* XXX dynamic? */
-	struct romfs_inode ri;
-	const char *name;		/* got from dentry */
-	int len;
-
-	res = -EACCES;			/* placeholder for "no data here" */
-	offset = dir->i_ino & ROMFH_MASK;
-	lock_kernel();
-	if (romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0)
-		goto error;
-
-	maxoff = romfs_maxsize(dir->i_sb);
-	offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
-
-	/* OK, now find the file whose name is in "dentry" in the
-	 * directory specified by "dir".  */
-
-	name = dentry->d_name.name;
-	len = dentry->d_name.len;
-
-	for(;;) {
-		if (!offset || offset >= maxoff)
-			goto success; /* negative success */
-		if (romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0)
-			goto error;
-
-		/* try to match the first 16 bytes of name */
-		fslen = romfs_strnlen(dir, offset+ROMFH_SIZE, ROMFH_SIZE);
-		if (len < ROMFH_SIZE) {
-			if (len == fslen) {
-				/* both are shorter, and same size */
-				romfs_copyfrom(dir, fsname, offset+ROMFH_SIZE, len+1);
-				if (strncmp (name, fsname, len) == 0)
-					break;
-			}
-		} else if (fslen >= ROMFH_SIZE) {
-			/* both are longer; XXX optimize max size */
-			fslen = romfs_strnlen(dir, offset+ROMFH_SIZE, sizeof(fsname)-1);
-			if (len == fslen) {
-				romfs_copyfrom(dir, fsname, offset+ROMFH_SIZE, len+1);
-				if (strncmp(name, fsname, len) == 0)
-					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)) {
-		res = PTR_ERR(inode);
-		goto error;
-	}
-
-success:
-	d_add(dentry, inode);
-	res = 0;
-error:
-	unlock_kernel();
-	return ERR_PTR(res);
-}
-
-/*
- * Ok, we do readpage, to be able to execute programs.  Unfortunately,
- * we can't use bmap, since we may have looser alignments.
- */
-
-static int
-romfs_readpage(struct file *file, struct page * page)
-{
-	struct inode *inode = page->mapping->host;
-	loff_t offset, size;
-	unsigned long filled;
-	void *buf;
-	int result = -EIO;
-
-	page_cache_get(page);
-	lock_kernel();
-	buf = kmap(page);
-	if (!buf)
-		goto err_out;
-
-	/* 32 bit warning -- but not for us :) */
-	offset = page_offset(page);
-	size = i_size_read(inode);
-	filled = 0;
-	result = 0;
-	if (offset < size) {
-		unsigned long readlen;
-
-		size -= offset;
-		readlen = size > PAGE_SIZE ? PAGE_SIZE : size;
-
-		filled = romfs_copyfrom(inode, buf, ROMFS_I(inode)->i_dataoffset+offset, readlen);
-
-		if (filled != readlen) {
-			SetPageError(page);
-			filled = 0;
-			result = -EIO;
-		}
-	}
-
-	if (filled < PAGE_SIZE)
-		memset(buf + filled, 0, PAGE_SIZE-filled);
-
-	if (!result)
-		SetPageUptodate(page);
-	flush_dcache_page(page);
-
-	unlock_page(page);
-
-	kunmap(page);
-err_out:
-	page_cache_release(page);
-	unlock_kernel();
-
-	return result;
-}
-
-/* Mapping from our types to the kernel */
-
-static const struct address_space_operations romfs_aops = {
-	.readpage = romfs_readpage
-};
-
-static const struct file_operations romfs_dir_operations = {
-	.read		= generic_read_dir,
-	.readdir	= romfs_readdir,
-};
-
-static const struct inode_operations romfs_dir_inode_operations = {
-	.lookup		= romfs_lookup,
-};
-
-static mode_t romfs_modemap[] =
-{
-	0, S_IFDIR+0644, S_IFREG+0644, S_IFLNK+0777,
-	S_IFBLK+0600, S_IFCHR+0600, S_IFSOCK+0644, S_IFIFO+0644
-};
-
-static struct inode *
-romfs_iget(struct super_block *sb, unsigned long ino)
-{
-	int nextfh, ret;
-	struct romfs_inode ri;
-	struct inode *i;
-
-	ino &= ROMFH_MASK;
-	i = iget_locked(sb, ino);
-	if (!i)
-		return ERR_PTR(-ENOMEM);
-	if (!(i->i_state & I_NEW))
-		return i;
-
-	i->i_mode = 0;
-
-	/* Loop for finding the real hard link */
-	for(;;) {
-		if (romfs_copyfrom(i, &ri, ino, ROMFH_SIZE) <= 0) {
-			printk(KERN_ERR "romfs: read error for inode 0x%lx\n",
-				ino);
-			iget_failed(i);
-			return ERR_PTR(-EIO);
-		}
-		/* XXX: do romfs_checksum here too (with name) */
-
-		nextfh = be32_to_cpu(ri.next);
-		if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
-			break;
-
-		ino = be32_to_cpu(ri.spec) & ROMFH_MASK;
-	}
-
-	i->i_nlink = 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;
-
-        /* Precalculate the data offset */
-	ret = romfs_strnlen(i, ino + ROMFH_SIZE, ROMFS_MAXFN);
-	if (ret >= 0)
-		ino = (ROMFH_SIZE + ret + 1 + ROMFH_PAD) & ROMFH_MASK;
-	else
-		ino = 0;
-
-        ROMFS_I(i)->i_metasize = ino;
-        ROMFS_I(i)->i_dataoffset = ino+(i->i_ino&ROMFH_MASK);
-
-        /* Compute permissions */
-        ino = romfs_modemap[nextfh & ROMFH_TYPE];
-	/* only "normal" files have ops */
-	switch (nextfh & ROMFH_TYPE) {
-		case 1:
-			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)
-				ino |= S_IXUGO;
-			i->i_mode = ino;
-			break;
-		case 2:
-			i->i_fop = &generic_ro_fops;
-			i->i_data.a_ops = &romfs_aops;
-			if (nextfh & ROMFH_EXEC)
-				ino |= S_IXUGO;
-			i->i_mode = ino;
-			break;
-		case 3:
-			i->i_op = &page_symlink_inode_operations;
-			i->i_data.a_ops = &romfs_aops;
-			i->i_mode = ino | S_IRWXUGO;
-			break;
-		default:
-			/* depending on MBZ for sock/fifos */
-			nextfh = be32_to_cpu(ri.spec);
-			init_special_inode(i, ino,
-					MKDEV(nextfh>>16,nextfh&0xffff));
-	}
-	unlock_new_inode(i);
-	return i;
-}
-
-static struct kmem_cache * romfs_inode_cachep;
-
-static struct inode *romfs_alloc_inode(struct super_block *sb)
-{
-	struct romfs_inode_info *ei;
-	ei = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL);
-	if (!ei)
-		return NULL;
-	return &ei->vfs_inode;
-}
-
-static void romfs_destroy_inode(struct inode *inode)
-{
-	kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
-}
-
-static void init_once(void *foo)
-{
-	struct romfs_inode_info *ei = foo;
-
-	inode_init_once(&ei->vfs_inode);
-}
-
-static int init_inodecache(void)
-{
-	romfs_inode_cachep = kmem_cache_create("romfs_inode_cache",
-					     sizeof(struct romfs_inode_info),
-					     0, (SLAB_RECLAIM_ACCOUNT|
-						SLAB_MEM_SPREAD),
-					     init_once);
-	if (romfs_inode_cachep == NULL)
-		return -ENOMEM;
-	return 0;
-}
-
-static void destroy_inodecache(void)
-{
-	kmem_cache_destroy(romfs_inode_cachep);
-}
-
-static int romfs_remount(struct super_block *sb, int *flags, char *data)
-{
-	*flags |= MS_RDONLY;
-	return 0;
-}
-
-static const struct super_operations romfs_ops = {
-	.alloc_inode	= romfs_alloc_inode,
-	.destroy_inode	= romfs_destroy_inode,
-	.statfs		= romfs_statfs,
-	.remount_fs	= romfs_remount,
-};
-
-static int romfs_get_sb(struct file_system_type *fs_type,
-	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
-{
-	return get_sb_bdev(fs_type, flags, dev_name, data, romfs_fill_super,
-			   mnt);
-}
-
-static struct file_system_type romfs_fs_type = {
-	.owner		= THIS_MODULE,
-	.name		= "romfs",
-	.get_sb		= romfs_get_sb,
-	.kill_sb	= kill_block_super,
-	.fs_flags	= FS_REQUIRES_DEV,
-};
-
-static int __init init_romfs_fs(void)
-{
-	int err = init_inodecache();
-	if (err)
-		goto out1;
-        err = register_filesystem(&romfs_fs_type);
-	if (err)
-		goto out;
-	return 0;
-out:
-	destroy_inodecache();
-out1:
-	return err;
-}
-
-static void __exit exit_romfs_fs(void)
-{
-	unregister_filesystem(&romfs_fs_type);
-	destroy_inodecache();
-}
-
-/* Yes, works even as a module... :) */
-
-module_init(init_romfs_fs)
-module_exit(exit_romfs_fs)
-MODULE_LICENSE("GPL");