/* inode.c
 * 
 * Inode and Superblock handling for the EFS filesystem
 *
 * (C) 1995,96 Christian Vogelgsang
 */
 
#include <linux/module.h>
#include <linux/init.h>		/* __initfunc */
#include <linux/fs.h>
#include <linux/efs_fs.h>
#include <linux/efs_fs_i.h>
#include <linux/efs_fs_sb.h>
#include <linux/locks.h>

#include <asm/uaccess.h>

/* ----- Define the operations for the Superblock ----- */
void efs_read_inode(struct inode *);
void efs_put_inode(struct inode *);
void efs_put_super(struct super_block *);
int efs_statfs(struct super_block *, struct statfs *,int );

static struct super_operations efs_sops = {
	efs_read_inode, 
	NULL, /* write_inode */
	efs_put_inode, /* put_inode */
	NULL, /* delete_inode */
	NULL, /* notify_change */
	efs_put_super, 
	NULL, /* write_super */
	efs_statfs, 
	NULL
};

static void efs_put_inode(struct inode *i) {
  printk("efs_put_inode: iput()ting inode %d\n", i->i_ino);
}


/* ----- Conversion utilities ----- 
   Get 16- and 32-bit unsigned values in big-endian format from a byte buffer
*/
__u32 ConvertLong(__u8 *buf, int offset)
{
	return *((__u32 *)(buf + offset));
	/*  return  (__u32)buf[offset+3] |
	    ((__u32)buf[offset+2])<<8 |
	    ((__u32)buf[offset+1])<<16 |
	    ((__u32)buf[offset])<<24;
	    */
}

__u16 ConvertShort(__u8 *buf, int offset)
{
	return *((__u16 *)(buf + offset));
	/*
	  return (__u16)buf[offset+1] |
	  ((__u16)buf[offset])<<8;
	  */
}


/* ----- Install/Remove Module ----- 
 These procedures are used to install/remove our filesystem
 module in the linux kernel
*/

/* describe filesystem */
struct super_block *efs_read_super(struct super_block *s, void *d, int sil);

static struct file_system_type efs_fs_type = {
	"efs",
	FS_REQUIRES_DEV,
	efs_read_super,
	NULL
};

__initfunc(int init_efs_fs(void)) {
	return register_filesystem(&efs_fs_type);
}

#ifdef MODULE
EXPORT_NO_SYMBOLS;

/* install module */
int init_module(void)
{
	return init_efs_fs();
}

/* remove module */
void cleanup_module(void)
{
	unregister_filesystem(&efs_fs_type);
}
#endif /* MODULE */

#ifdef DEBUG_EFS
void efs_dump_super(struct efs_super_block *sb) {
	printk("efs_super_block @ 0x%p:\n", sb);
	printk("size:     %0#8lX   firstcg:  %0#8lX\n", sb->s_size, sb->s_firstcg);
	printk("cgfsize:  %0#8lX   cgisize:  %0#8hX\n", sb->s_cgfsize,sb->s_cgisize);
	printk("sectors:  %0#8hX   heads:    %0#8hX\n", sb->s_sectors, sb->s_heads);
	printk("ncg:      %0#8hX   dirty:    %0#8hX\n", sb->s_ncg, sb->s_dirty);
	printk("time:     %0#8lX   magic:    %0#8lX\n", sb->s_time, sb->s_magic);
	printk("fname:    %.6s   fpack:    %.6s\n", sb->s_fname, sb->s_fpack);
	printk("bmsize:   %0#8lX   tfree:    %0#8lX\n", sb->s_bmsize, sb->s_tfree);
	printk("tinode:   %0#8lX   bmblock:  %0#8lX\n", sb->s_tinode, sb->s_bmblock);
	printk("replsb:   %0#8lX   lastiall: %0#8lX\n", sb->s_replsb,
	       sb->s_lastialloc);
	printk("checksum: %0#8lX\n", sb->s_checksum);
} 

void efs_dump_inode(struct efs_disk_inode *di) {
	printk("efs_disk_inode @ 0x%p: ", di);
	printk("[%o %hd %hd %u %u %u %u %u #ext=%hd %u %u]\n",
	       di->di_mode, di->di_nlink, di->di_uid, di->di_gid, di->di_size,
	       di->di_atime, di->di_mtime, di->di_ctime, di->di_gen, 
	       di->di_numextents, di->di_version);
}
#endif

/* ----- efs_checkVolDesc -----
   Analyse the first block of a CD and check 
   if it's a valid efs volume descriptor

   blk    - buffer with the data of first block
   silent - 0 -> verbose

   return : 0 - error ; >0 - start block of filesystem
*/
#if 0
static __u32 efs_checkVolDesc(__u8 *blk,int silent)
{
	__u32 magic;
	__u8 *ptr;
	__u8 name[10];
	__u32 pos,len;
	int i;

	/* is the magic cookie here? */
	magic = ConvertLong(blk,0);
	if(magic!=0x0be5a941) {
		printk("EFS: no magic on first block\n");
		return 0;
	}
  
	/* Walk through the entries of the VD */
	/* Quite useless, but gives nice output ;-) */
	ptr = blk + EFS_VD_ENTRYFIRST;
	name[8] = 0;
	while(*ptr) {
		for(i=0;i<8;i++)
			name[i] = ptr[i];

		/* start and length of entry */
		pos = ConvertLong(ptr,EFS_VD_ENTRYPOS);
		len = ConvertLong(ptr,EFS_VD_ENTRYLEN);

		if(!silent) 
			printk("EFS: VolDesc: %8s blk: %08lx len: %08lx\n",
			       name,pos,len);
    
		ptr+=EFS_VD_ENTRYSIZE;
	}

	pos = ConvertLong(blk,EFS_VD_FS_START);
	printk("EFS: FS start: %08lx\n",pos);
	return pos;
}
#endif

/* ----- efs_checkSuper ----- 
 Check if the given block is a valid EFS-superblock
 
 sbi    - my EFS superblock info
 block  - block that must be examined

 return - 0 ok, -1 error
*/
static int efs_verify_super(struct efs_super_block *sb, 
			    struct efs_sb_info *sbi, 
			    int silent)
{
	__u32    magic;

	magic = sb->s_magic;
	/* check if the magic cookie is here */
	if((magic!=EFS_MAGIC1)&&(magic!=EFS_MAGIC2)) {
		printk("EFS: magic %#X doesn't match %#X or %#X!\n",
		       magic, EFS_MAGIC1, EFS_MAGIC2);
		return -1;
	}

	/* XXX should check csum */
  
	sbi->total_blocks = sb->s_size;
	sbi->first_block  = sb->s_firstcg;
	sbi->group_size   = sb->s_cgfsize;
	sbi->inode_blocks = sb->s_cgisize;
	sbi->total_groups = sb->s_ncg;
    
	return 0;    
}


/* ----- efs_read_super ----- 
   read_super: if the fs gets mounted this procedure is called to
   check if the filesystem is valid and to fill the superblock struct
   
   s     - superblock struct
   d     - options for fs (unused)
   sil   - flag to be silent
   
   return - filled s struct or NULL on error
 */

struct super_block *efs_read_super(struct super_block *s, void *d, int silent)
{
	struct buffer_head *bh;
	struct efs_sb_info *sb_info = (struct efs_sb_info *)&s->u.efs_sb;
	struct efs_super_block *es;
	int error = 0;
	int dev = s->s_dev;
	struct inode *root_inode = NULL;

	MOD_INC_USE_COUNT;
  
	/* say hello to my log file! */
#ifdef EFS_DEBUG
	if(!silent)
		printk("EFS: --- Filesystem ---\n");
#endif
	/* set blocksize to 512 */
	set_blocksize(dev, EFS_BLOCK_SIZE);
  
	lock_super(s);
  
#if 0  
	/* Read first block of CD: the Volume Descriptor */
	bh = bread(dev, 0, EFS_BLOCK_SIZE);
	if(bh) {
		sb_info->fs_start = efs_checkVolDesc((__u8 *)bh->b_data,silent);
		if(sb_info->fs_start==0) {
			printk("EFS: failed checking Volume Descriptor\n");
			/* error++; */
		}
		brelse(bh);
	} else {
		printk("EFS: cannot read the first block\n");
		error++;
	}
#endif 0

	/* Read the Superblock */
	if(!error) {	
#ifdef DEBUG_EFS
		if (!silent)
			printk("EFS: reading superblock.\n");
#endif
		bh = bread(dev, EFS_BLK_SUPER,  EFS_BLOCK_SIZE );
		if(bh) {
			es = (struct efs_super_block *)(bh->b_data);
#ifdef DEBUG_EFS
			if(!silent)
				efs_dump_super(es);
#endif
			if(efs_verify_super(es, sb_info, silent)) {
				printk("EFS: failed checking Superblock\n");
				error++;
			}
			brelse(bh);
		} else {
			printk("EFS: cannot read the superblock\n");
			error++;
		}
	} 
  
	if(!error) {
		s->s_blocksize = EFS_BLOCK_SIZE;
		s->s_blocksize_bits = EFS_BLOCK_SIZE_BITS;
    
		s->s_magic	= EFS_SUPER_MAGIC;
		s->s_flags	= MS_RDONLY;
		s->s_op	= &efs_sops;
		s->s_dev	= dev;
		root_inode = iget(s, EFS_ROOT_INODE);
		s->s_root = d_alloc_root(root_inode, NULL);
		if (!s->s_root) {
			error++;
			printk("EFS: couldn't allocate root inode!\n");
		}
	}

	unlock_super(s);
  
	if(check_disk_change(s->s_dev)) {
		printk("EFS: Device changed!\n");
		error++;
	}

	/* We found errors -> say goodbye! */
	if(error) {
		s->s_dev = 0;
		d_delete(s->s_root);	/* XXX is this enough? */
		printk("EFS: init failed with %d errors\n", error);
		brelse(bh);
		MOD_DEC_USE_COUNT;
		return NULL;
	} 

	return s;
}


/* ----- efs_put_super ----- 
   put_super: remove the filesystem and the module use count

   s - superblock
*/
void efs_put_super(struct super_block *s)
{
	lock_super(s);
	s->s_dev = 0;
	unlock_super(s);
	MOD_DEC_USE_COUNT;
}


/* ----- efs_statfs ----- 
   statfs: get informatio on the filesystem
   
   s   - superblock of fs
   buf - statfs struct that has to be filled
*/
int efs_statfs(struct super_block *s, struct statfs *buf,int bufsize)
{
	struct efs_sb_info *sbi = (struct efs_sb_info *)&s->u.generic_sbp;
	struct statfs tmp;

	tmp.f_type = EFS_SUPER_MAGIC;
	tmp.f_bsize = EFS_BLOCK_SIZE;
	tmp.f_blocks = sbi->total_blocks;
	tmp.f_bfree = 0;
	tmp.f_bavail = 0;
	tmp.f_files = 100; /* don't know how to calculate the correct value */
	tmp.f_ffree = 0;
	tmp.f_namelen = NAME_MAX;

	return copy_to_user(buf,&tmp,bufsize) ? -EFAULT : 0;
}


/* ----- efs_read_inode ----- 
   read an inode specified by in->i_ino from disk, fill the inode
   structure and install the correct handler for the file type
   
   in   - inode struct
*/
void efs_read_inode(struct inode *in)
{
	struct buffer_head *bh;
	struct efs_sb_info *sbi = (struct efs_sb_info *)&in->i_sb->u.generic_sbp;
	__u32 blk,off;
	int error = 0;
  
	/* Calc the discblock and the offset for inode (4 Nodes fit in one block) */
	blk = in->i_ino >> 2; 
	blk = sbi->fs_start + sbi->first_block + 
		(sbi->group_size * (blk / sbi->inode_blocks)) +
		(blk % sbi->inode_blocks);
	off = (in->i_ino&3)<<7;
  
	/* Read the block with the inode from disk */
#ifdef DEBUG_EFS
	printk("EFS: looking for inode %#lx\n", in->i_ino);
#endif
	bh = bread(in->i_dev,blk,EFS_BLOCK_SIZE);
	if(bh) {
    
		struct efs_disk_inode *di = (struct efs_disk_inode *)(bh->b_data + off);
		__u16 numext;
		struct efs_inode_info *ini = &in->u.efs_i;
		__u32 rdev;
		int i;
    
		/* fill in standard inode infos */
		in->i_mtime = efs_swab32(di->di_mtime);
		in->i_ctime = efs_swab32(di->di_ctime);
		in->i_atime = efs_swab32(di->di_atime);
		in->i_size  = efs_swab32(di->di_size);
		in->i_nlink = efs_swab16(di->di_nlink);
		in->i_uid   = efs_swab16(di->di_uid);
		in->i_gid   = efs_swab16(di->di_gid);
		in->i_mode  = efs_swab16(di->di_mode);

		/* Special files store their rdev value where the extends of
		   a regular file are found */
		/*    rdev = ConvertLong(rawnode,EFS_IN_EXTENTS);*/
		/* XXX this isn't right */
		rdev = efs_swab32(*(__u32 *)&di->di_u.di_dev); 
    
		/* -----------------------------------------------------------------
		   The following values are stored in my private part of the Inode.
		   They are necessary for further operations with the file */

		/* get the number of extends the inode posseses */
		numext = efs_swab16(di->di_numextents);

		/* if this inode has more than EFS_MAX_EXTENDS then the extends are
		   stored not directly in the inode but indirect on an extra block.
		   The address of the extends-block is stored in the inode */
		if(numext>EFS_MAX_EXTENTS) { 
			struct buffer_head *bh2;
			printk("EFS: inode #%lx has > EFS_MAX_EXTENTS (%d)\n",
			       in->i_ino, numext);

			/* Store the discblock and offset of extend-list in Inode info */
			ini->extblk = sbi->fs_start + efs_swab32((__u32)(di->di_u.di_extents));

			/* read INI_MAX_EXT extents from the indirect block */
			printk("EFS: ");
			bh2 = bread(in->i_dev,ini->extblk,EFS_BLOCK_SIZE);
			if(bh2) {
			  union efs_extent *ptr = 
			    (union efs_extent *)bh2->b_data;
				for(i=0;i<EFS_MAX_EXTENTS;i++) {
					ini->extents[i].ex_bytes[0] = efs_swab32(ptr[i].ex_bytes[0]);
					ini->extents[i].ex_bytes[1] = efs_swab32(ptr[i].ex_bytes[1]);
				}
				brelse(bh2);
			} else
				printk("efs: failed reading indirect extents!\n");

		} else {
#ifdef DEBUG_EFS
			printk("EFS: inode %#lx is direct (woohoo!)\n",
			       in->i_ino);
#endif
			/* The extends are found in the inode block */
			ini->extblk = blk;
      
			/* copy extends directly from rawinode */
			for(i=0;i<numext;i++) {
				ini->extents[i].ex_bytes[0] = efs_swab32(di->di_u.di_extents[i].ex_bytes[0]);
				ini->extents[i].ex_bytes[1] = efs_swab32(di->di_u.di_extents[i].ex_bytes[1]);
			}
		}
		ini->tot = numext;
		ini->cur = 0;

		brelse(bh);
    
#ifdef DEBUG_EFS
		printk("%lx inode: blk %lx numext %x\n",in->i_ino,ini->extblk,numext);
		efs_dump_inode(di);
#endif

		/* Install the filetype Handler */
		switch(in->i_mode & S_IFMT) {
		case S_IFDIR: 
			in->i_op = &efs_dir_in_ops; 
			break;
		case S_IFREG:
			in->i_op = &efs_file_in_ops;
			break;
		case S_IFLNK:
			in->i_op = &efs_symlink_in_ops;
			break;
		case S_IFCHR:
			in->i_rdev = rdev;
			in->i_op = &chrdev_inode_operations; 
			break;
		case S_IFBLK:
			in->i_rdev = rdev;
			in->i_op = &blkdev_inode_operations; 
			break;
		case S_IFIFO:
			init_fifo(in);
			break;    
		default:
			printk("EFS: Unsupported inode Mode %o\n",(unsigned int)(in->i_mode));
			error++;
			break;
		}
        
	} else {
		printk("EFS: Inode: failed bread!\n");
		error++;
	}
  
	/* failed inode */
	if(error) {
		printk("EFS: read inode failed with %d errors\n",error);
		in->i_mtime = in->i_atime = in->i_ctime = 0;
		in->i_size = 0;
		in->i_nlink = 1;
		in->i_uid = in->i_gid = 0;
		in->i_mode = S_IFREG;
		in->i_op = NULL;   
	}
}