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|
/*
* 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;
};
/* 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 list_entry(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 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;
/* 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 = iget(s, sz);
if (!root)
goto out;
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 -EINVAL;
}
/* That's simple too. */
static int
romfs_statfs(struct super_block *sb, 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(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
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