/*
   * Optimized MPEG FS - inode and super operations.
   * Copyright (C) 2006 Bob Copeland <me@bobcopeland.com>
   * Released under GPL v2.
   */

  #include <linux/module.h>
  #include <linux/sched.h>

  #include <linux/slab.h>

  #include <linux/fs.h>
  #include <linux/vfs.h>
  #include <linux/parser.h>
  #include <linux/buffer_head.h>
  #include <linux/vmalloc.h>

  #include <linux/writeback.h>

  #include <linux/crc-itu-t.h>
  #include "omfs.h"
  
  MODULE_AUTHOR("Bob Copeland <me@bobcopeland.com>");
  MODULE_DESCRIPTION("OMFS (ReplayTV/Karma) Filesystem for Linux");
  MODULE_LICENSE("GPL");

  struct buffer_head *omfs_bread(struct super_block *sb, sector_t block)
  {
  	struct omfs_sb_info *sbi = OMFS_SB(sb);
  	if (block >= sbi->s_num_blocks)
  		return NULL;
  
  	return sb_bread(sb, clus_to_blk(sbi, block));
  }

  struct inode *omfs_new_inode(struct inode *dir, umode_t mode)

  {
  	struct inode *inode;
  	u64 new_block;
  	int err;
  	int len;
  	struct omfs_sb_info *sbi = OMFS_SB(dir->i_sb);
  
  	inode = new_inode(dir->i_sb);
  	if (!inode)
  		return ERR_PTR(-ENOMEM);
  
  	err = omfs_allocate_range(dir->i_sb, sbi->s_mirrors, sbi->s_mirrors,
  			&new_block, &len);
  	if (err)
  		goto fail;
  
  	inode->i_ino = new_block;

  	inode_init_owner(inode, NULL, mode);

  	inode->i_mapping->a_ops = &omfs_aops;
  
  	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  	switch (mode & S_IFMT) {
  	case S_IFDIR:
  		inode->i_op = &omfs_dir_inops;
  		inode->i_fop = &omfs_dir_operations;
  		inode->i_size = sbi->s_sys_blocksize;
  		inc_nlink(inode);
  		break;
  	case S_IFREG:
  		inode->i_op = &omfs_file_inops;
  		inode->i_fop = &omfs_file_operations;
  		inode->i_size = 0;
  		break;
  	}
  
  	insert_inode_hash(inode);
  	mark_inode_dirty(inode);
  	return inode;
  fail:
  	make_bad_inode(inode);
  	iput(inode);
  	return ERR_PTR(err);
  }
  
  /*
   * Update the header checksums for a dirty inode based on its contents.
   * Caller is expected to hold the buffer head underlying oi and mark it
   * dirty.
   */
  static void omfs_update_checksums(struct omfs_inode *oi)
  {
  	int xor, i, ofs = 0, count;
  	u16 crc = 0;
  	unsigned char *ptr = (unsigned char *) oi;
  
  	count = be32_to_cpu(oi->i_head.h_body_size);
  	ofs = sizeof(struct omfs_header);
  
  	crc = crc_itu_t(crc, ptr + ofs, count);
  	oi->i_head.h_crc = cpu_to_be16(crc);
  
  	xor = ptr[0];
  	for (i = 1; i < OMFS_XOR_COUNT; i++)
  		xor ^= ptr[i];
  
  	oi->i_head.h_check_xor = xor;
  }

  static int __omfs_write_inode(struct inode *inode, int wait)

  {
  	struct omfs_inode *oi;
  	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
  	struct buffer_head *bh, *bh2;

  	u64 ctime;
  	int i;
  	int ret = -EIO;
  	int sync_failed = 0;
  
  	/* get current inode since we may have written sibling ptrs etc. */

  	bh = omfs_bread(inode->i_sb, inode->i_ino);

  	if (!bh)
  		goto out;
  
  	oi = (struct omfs_inode *) bh->b_data;
  
  	oi->i_head.h_self = cpu_to_be64(inode->i_ino);
  	if (S_ISDIR(inode->i_mode))
  		oi->i_type = OMFS_DIR;
  	else if (S_ISREG(inode->i_mode))
  		oi->i_type = OMFS_FILE;
  	else {
  		printk(KERN_WARNING "omfs: unknown file type: %d
  ",
  			inode->i_mode);
  		goto out_brelse;
  	}
  
  	oi->i_head.h_body_size = cpu_to_be32(sbi->s_sys_blocksize -
  		sizeof(struct omfs_header));
  	oi->i_head.h_version = 1;
  	oi->i_head.h_type = OMFS_INODE_NORMAL;
  	oi->i_head.h_magic = OMFS_IMAGIC;
  	oi->i_size = cpu_to_be64(inode->i_size);
  
  	ctime = inode->i_ctime.tv_sec * 1000LL +
  		((inode->i_ctime.tv_nsec + 999)/1000);
  	oi->i_ctime = cpu_to_be64(ctime);
  
  	omfs_update_checksums(oi);
  
  	mark_buffer_dirty(bh);
  	if (wait) {
  		sync_dirty_buffer(bh);
  		if (buffer_req(bh) && !buffer_uptodate(bh))
  			sync_failed = 1;
  	}
  
  	/* if mirroring writes, copy to next fsblock */
  	for (i = 1; i < sbi->s_mirrors; i++) {

  		bh2 = omfs_bread(inode->i_sb, inode->i_ino + i);

  		if (!bh2)
  			goto out_brelse;
  
  		memcpy(bh2->b_data, bh->b_data, bh->b_size);
  		mark_buffer_dirty(bh2);
  		if (wait) {
  			sync_dirty_buffer(bh2);
  			if (buffer_req(bh2) && !buffer_uptodate(bh2))
  				sync_failed = 1;
  		}
  		brelse(bh2);
  	}
  	ret = (sync_failed) ? -EIO : 0;
  out_brelse:
  	brelse(bh);
  out:
  	return ret;
  }

  static int omfs_write_inode(struct inode *inode, struct writeback_control *wbc)
  {
  	return __omfs_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
  }

  int omfs_sync_inode(struct inode *inode)
  {

  	return __omfs_write_inode(inode, 1);

  }
  
  /*
   * called when an entry is deleted, need to clear the bits in the
   * bitmaps.
   */

  static void omfs_evict_inode(struct inode *inode)

  {
  	truncate_inode_pages(&inode->i_data, 0);

  	end_writeback(inode);
  
  	if (inode->i_nlink)
  		return;

  
  	if (S_ISREG(inode->i_mode)) {
  		inode->i_size = 0;
  		omfs_shrink_inode(inode);
  	}
  
  	omfs_clear_range(inode->i_sb, inode->i_ino, 2);

  }
  
  struct inode *omfs_iget(struct super_block *sb, ino_t ino)
  {
  	struct omfs_sb_info *sbi = OMFS_SB(sb);
  	struct omfs_inode *oi;
  	struct buffer_head *bh;

  	u64 ctime;
  	unsigned long nsecs;
  	struct inode *inode;
  
  	inode = iget_locked(sb, ino);
  	if (!inode)
  		return ERR_PTR(-ENOMEM);
  	if (!(inode->i_state & I_NEW))
  		return inode;

  	bh = omfs_bread(inode->i_sb, ino);

  	if (!bh)
  		goto iget_failed;
  
  	oi = (struct omfs_inode *)bh->b_data;
  
  	/* check self */
  	if (ino != be64_to_cpu(oi->i_head.h_self))
  		goto fail_bh;
  
  	inode->i_uid = sbi->s_uid;
  	inode->i_gid = sbi->s_gid;
  
  	ctime = be64_to_cpu(oi->i_ctime);
  	nsecs = do_div(ctime, 1000) * 1000L;
  
  	inode->i_atime.tv_sec = ctime;
  	inode->i_mtime.tv_sec = ctime;
  	inode->i_ctime.tv_sec = ctime;
  	inode->i_atime.tv_nsec = nsecs;
  	inode->i_mtime.tv_nsec = nsecs;
  	inode->i_ctime.tv_nsec = nsecs;
  
  	inode->i_mapping->a_ops = &omfs_aops;
  
  	switch (oi->i_type) {
  	case OMFS_DIR:
  		inode->i_mode = S_IFDIR | (S_IRWXUGO & ~sbi->s_dmask);
  		inode->i_op = &omfs_dir_inops;
  		inode->i_fop = &omfs_dir_operations;

  		inode->i_size = sbi->s_sys_blocksize;

  		inc_nlink(inode);
  		break;
  	case OMFS_FILE:
  		inode->i_mode = S_IFREG | (S_IRWXUGO & ~sbi->s_fmask);
  		inode->i_fop = &omfs_file_operations;
  		inode->i_size = be64_to_cpu(oi->i_size);
  		break;
  	}
  	brelse(bh);
  	unlock_new_inode(inode);
  	return inode;
  fail_bh:
  	brelse(bh);
  iget_failed:
  	iget_failed(inode);
  	return ERR_PTR(-EIO);
  }
  
  static void omfs_put_super(struct super_block *sb)
  {
  	struct omfs_sb_info *sbi = OMFS_SB(sb);
  	kfree(sbi->s_imap);
  	kfree(sbi);
  	sb->s_fs_info = NULL;
  }
  
  static int omfs_statfs(struct dentry *dentry, struct kstatfs *buf)
  {
  	struct super_block *s = dentry->d_sb;
  	struct omfs_sb_info *sbi = OMFS_SB(s);

  	u64 id = huge_encode_dev(s->s_bdev->bd_dev);

  	buf->f_type = OMFS_MAGIC;
  	buf->f_bsize = sbi->s_blocksize;
  	buf->f_blocks = sbi->s_num_blocks;
  	buf->f_files = sbi->s_num_blocks;
  	buf->f_namelen = OMFS_NAMELEN;

  	buf->f_fsid.val[0] = (u32)id;
  	buf->f_fsid.val[1] = (u32)(id >> 32);

  
  	buf->f_bfree = buf->f_bavail = buf->f_ffree =
  		omfs_count_free(s);

  	return 0;
  }

  static const struct super_operations omfs_sops = {

  	.write_inode	= omfs_write_inode,

  	.evict_inode	= omfs_evict_inode,

  	.put_super	= omfs_put_super,
  	.statfs		= omfs_statfs,
  	.show_options	= generic_show_options,
  };
  
  /*
   * For Rio Karma, there is an on-disk free bitmap whose location is
   * stored in the root block.  For ReplayTV, there is no such free bitmap
   * so we have to walk the tree.  Both inodes and file data are allocated
   * from the same map.  This array can be big (300k) so we allocate
   * in units of the blocksize.
   */
  static int omfs_get_imap(struct super_block *sb)
  {
  	int bitmap_size;
  	int array_size;
  	int count;
  	struct omfs_sb_info *sbi = OMFS_SB(sb);
  	struct buffer_head *bh;
  	unsigned long **ptr;
  	sector_t block;
  
  	bitmap_size = DIV_ROUND_UP(sbi->s_num_blocks, 8);
  	array_size = DIV_ROUND_UP(bitmap_size, sb->s_blocksize);
  
  	if (sbi->s_bitmap_ino == ~0ULL)
  		goto out;
  
  	sbi->s_imap_size = array_size;
  	sbi->s_imap = kzalloc(array_size * sizeof(unsigned long *), GFP_KERNEL);
  	if (!sbi->s_imap)
  		goto nomem;
  
  	block = clus_to_blk(sbi, sbi->s_bitmap_ino);

  	if (block >= sbi->s_num_blocks)
  		goto nomem;

  	ptr = sbi->s_imap;
  	for (count = bitmap_size; count > 0; count -= sb->s_blocksize) {
  		bh = sb_bread(sb, block++);
  		if (!bh)
  			goto nomem_free;
  		*ptr = kmalloc(sb->s_blocksize, GFP_KERNEL);
  		if (!*ptr) {
  			brelse(bh);
  			goto nomem_free;
  		}
  		memcpy(*ptr, bh->b_data, sb->s_blocksize);
  		if (count < sb->s_blocksize)
  			memset((void *)*ptr + count, 0xff,
  				sb->s_blocksize - count);
  		brelse(bh);
  		ptr++;
  	}
  out:
  	return 0;
  
  nomem_free:
  	for (count = 0; count < array_size; count++)
  		kfree(sbi->s_imap[count]);
  
  	kfree(sbi->s_imap);
  nomem:
  	sbi->s_imap = NULL;
  	sbi->s_imap_size = 0;
  	return -ENOMEM;
  }
  
  enum {
  	Opt_uid, Opt_gid, Opt_umask, Opt_dmask, Opt_fmask
  };

  static const match_table_t tokens = {

  	{Opt_uid, "uid=%u"},
  	{Opt_gid, "gid=%u"},
  	{Opt_umask, "umask=%o"},
  	{Opt_dmask, "dmask=%o"},
  	{Opt_fmask, "fmask=%o"},
  };
  
  static int parse_options(char *options, struct omfs_sb_info *sbi)
  {
  	char *p;
  	substring_t args[MAX_OPT_ARGS];
  	int option;
  
  	if (!options)
  		return 1;
  
  	while ((p = strsep(&options, ",")) != NULL) {
  		int token;
  		if (!*p)
  			continue;
  
  		token = match_token(p, tokens, args);
  		switch (token) {
  		case Opt_uid:
  			if (match_int(&args[0], &option))
  				return 0;
  			sbi->s_uid = option;
  			break;
  		case Opt_gid:
  			if (match_int(&args[0], &option))
  				return 0;
  			sbi->s_gid = option;
  			break;
  		case Opt_umask:
  			if (match_octal(&args[0], &option))
  				return 0;
  			sbi->s_fmask = sbi->s_dmask = option;
  			break;
  		case Opt_dmask:
  			if (match_octal(&args[0], &option))
  				return 0;
  			sbi->s_dmask = option;
  			break;
  		case Opt_fmask:
  			if (match_octal(&args[0], &option))
  				return 0;
  			sbi->s_fmask = option;
  			break;
  		default:
  			return 0;
  		}
  	}
  	return 1;
  }
  
  static int omfs_fill_super(struct super_block *sb, void *data, int silent)
  {
  	struct buffer_head *bh, *bh2;
  	struct omfs_super_block *omfs_sb;
  	struct omfs_root_block *omfs_rb;
  	struct omfs_sb_info *sbi;
  	struct inode *root;

  	int ret = -EINVAL;
  
  	save_mount_options(sb, (char *) data);
  
  	sbi = kzalloc(sizeof(struct omfs_sb_info), GFP_KERNEL);
  	if (!sbi)
  		return -ENOMEM;
  
  	sb->s_fs_info = sbi;

  	sbi->s_uid = current_uid();
  	sbi->s_gid = current_gid();

  	sbi->s_dmask = sbi->s_fmask = current_umask();

  
  	if (!parse_options((char *) data, sbi))
  		goto end;
  
  	sb->s_maxbytes = 0xffffffff;
  
  	sb_set_blocksize(sb, 0x200);
  
  	bh = sb_bread(sb, 0);
  	if (!bh)
  		goto end;
  
  	omfs_sb = (struct omfs_super_block *)bh->b_data;
  
  	if (omfs_sb->s_magic != cpu_to_be32(OMFS_MAGIC)) {
  		if (!silent)
  			printk(KERN_ERR "omfs: Invalid superblock (%x)
  ",
  				   omfs_sb->s_magic);
  		goto out_brelse_bh;
  	}
  	sb->s_magic = OMFS_MAGIC;
  
  	sbi->s_num_blocks = be64_to_cpu(omfs_sb->s_num_blocks);
  	sbi->s_blocksize = be32_to_cpu(omfs_sb->s_blocksize);
  	sbi->s_mirrors = be32_to_cpu(omfs_sb->s_mirrors);
  	sbi->s_root_ino = be64_to_cpu(omfs_sb->s_root_block);
  	sbi->s_sys_blocksize = be32_to_cpu(omfs_sb->s_sys_blocksize);
  	mutex_init(&sbi->s_bitmap_lock);
  
  	if (sbi->s_sys_blocksize > PAGE_SIZE) {
  		printk(KERN_ERR "omfs: sysblock size (%d) is out of range
  ",
  			sbi->s_sys_blocksize);
  		goto out_brelse_bh;
  	}
  
  	if (sbi->s_blocksize < sbi->s_sys_blocksize ||
  	    sbi->s_blocksize > OMFS_MAX_BLOCK_SIZE) {
  		printk(KERN_ERR "omfs: block size (%d) is out of range
  ",
  			sbi->s_blocksize);
  		goto out_brelse_bh;
  	}
  
  	/*
  	 * Use sys_blocksize as the fs block since it is smaller than a
  	 * page while the fs blocksize can be larger.
  	 */
  	sb_set_blocksize(sb, sbi->s_sys_blocksize);
  
  	/*
  	 * ...and the difference goes into a shift.  sys_blocksize is always
  	 * a power of two factor of blocksize.
  	 */
  	sbi->s_block_shift = get_bitmask_order(sbi->s_blocksize) -
  		get_bitmask_order(sbi->s_sys_blocksize);

  	bh2 = omfs_bread(sb, be64_to_cpu(omfs_sb->s_root_block));

  	if (!bh2)
  		goto out_brelse_bh;
  
  	omfs_rb = (struct omfs_root_block *)bh2->b_data;
  
  	sbi->s_bitmap_ino = be64_to_cpu(omfs_rb->r_bitmap);
  	sbi->s_clustersize = be32_to_cpu(omfs_rb->r_clustersize);
  
  	if (sbi->s_num_blocks != be64_to_cpu(omfs_rb->r_num_blocks)) {
  		printk(KERN_ERR "omfs: block count discrepancy between "
  			"super and root blocks (%llx, %llx)
  ",

  			(unsigned long long)sbi->s_num_blocks,
  			(unsigned long long)be64_to_cpu(omfs_rb->r_num_blocks));

  		goto out_brelse_bh2;
  	}

  	if (sbi->s_bitmap_ino != ~0ULL &&
  	    sbi->s_bitmap_ino > sbi->s_num_blocks) {
  		printk(KERN_ERR "omfs: free space bitmap location is corrupt "
  			"(%llx, total blocks %llx)
  ",
  			(unsigned long long) sbi->s_bitmap_ino,
  			(unsigned long long) sbi->s_num_blocks);
  		goto out_brelse_bh2;
  	}

  	if (sbi->s_clustersize < 1 ||
  	    sbi->s_clustersize > OMFS_MAX_CLUSTER_SIZE) {
  		printk(KERN_ERR "omfs: cluster size out of range (%d)",
  			sbi->s_clustersize);
  		goto out_brelse_bh2;
  	}

  	ret = omfs_get_imap(sb);
  	if (ret)
  		goto out_brelse_bh2;
  
  	sb->s_op = &omfs_sops;
  
  	root = omfs_iget(sb, be64_to_cpu(omfs_rb->r_root_dir));
  	if (IS_ERR(root)) {
  		ret = PTR_ERR(root);
  		goto out_brelse_bh2;
  	}
  
  	sb->s_root = d_alloc_root(root);
  	if (!sb->s_root) {
  		iput(root);
  		goto out_brelse_bh2;
  	}
  	printk(KERN_DEBUG "omfs: Mounted volume %s
  ", omfs_rb->r_name);
  
  	ret = 0;
  out_brelse_bh2:
  	brelse(bh2);
  out_brelse_bh:
  	brelse(bh);
  end:

  	if (ret)
  		kfree(sbi);

  	return ret;
  }

  static struct dentry *omfs_mount(struct file_system_type *fs_type,
  			int flags, const char *dev_name, void *data)

  {

  	return mount_bdev(fs_type, flags, dev_name, data, omfs_fill_super);

  }
  
  static struct file_system_type omfs_fs_type = {
  	.owner = THIS_MODULE,
  	.name = "omfs",

  	.mount = omfs_mount,

  	.kill_sb = kill_block_super,
  	.fs_flags = FS_REQUIRES_DEV,
  };
  
  static int __init init_omfs_fs(void)
  {
  	return register_filesystem(&omfs_fs_type);
  }
  
  static void __exit exit_omfs_fs(void)
  {
  	unregister_filesystem(&omfs_fs_type);
  }
  
  module_init(init_omfs_fs);
  module_exit(exit_omfs_fs);