/*
   *	fs/bfs/dir.c
   *	BFS directory operations.
   *	Copyright (C) 1999,2000  Tigran Aivazian <tigran@veritas.com>
   *      Made endianness-clean by Andrew Stribblehill <ads@wompom.org> 2005
   */
  
  #include <linux/time.h>
  #include <linux/string.h>
  #include <linux/fs.h>
  #include <linux/buffer_head.h>
  #include <linux/sched.h>
  #include "bfs.h"
  
  #undef DEBUG
  
  #ifdef DEBUG
  #define dprintf(x...)	printf(x)
  #else
  #define dprintf(x...)
  #endif
  
  static int bfs_add_entry(struct inode *dir, const unsigned char *name,
  						int namelen, int ino);
  static struct buffer_head *bfs_find_entry(struct inode *dir,
  				const unsigned char *name, int namelen,
  				struct bfs_dirent **res_dir);
  
  static int bfs_readdir(struct file *f, struct dir_context *ctx)
  {
  	struct inode *dir = file_inode(f);
  	struct buffer_head *bh;
  	struct bfs_dirent *de;
  	unsigned int offset;
  	int block;
  
  	if (ctx->pos & (BFS_DIRENT_SIZE - 1)) {
  		printf("Bad f_pos=%08lx for %s:%08lx
  ",
  					(unsigned long)ctx->pos,
  					dir->i_sb->s_id, dir->i_ino);
  		return -EINVAL;
  	}
  
  	while (ctx->pos < dir->i_size) {
  		offset = ctx->pos & (BFS_BSIZE - 1);
  		block = BFS_I(dir)->i_sblock + (ctx->pos >> BFS_BSIZE_BITS);
  		bh = sb_bread(dir->i_sb, block);
  		if (!bh) {
  			ctx->pos += BFS_BSIZE - offset;
  			continue;
  		}
  		do {
  			de = (struct bfs_dirent *)(bh->b_data + offset);
  			if (de->ino) {
  				int size = strnlen(de->name, BFS_NAMELEN);
  				if (!dir_emit(ctx, de->name, size,
  						le16_to_cpu(de->ino),
  						DT_UNKNOWN)) {
  					brelse(bh);
  					return 0;
  				}
  			}
  			offset += BFS_DIRENT_SIZE;
  			ctx->pos += BFS_DIRENT_SIZE;
  		} while ((offset < BFS_BSIZE) && (ctx->pos < dir->i_size));
  		brelse(bh);
  	}
  	return 0;
  }
  
  const struct file_operations bfs_dir_operations = {
  	.read		= generic_read_dir,
  	.iterate	= bfs_readdir,
  	.fsync		= generic_file_fsync,
  	.llseek		= generic_file_llseek,
  };
  
  extern void dump_imap(const char *, struct super_block *);
  
  static int bfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
  						bool excl)
  {
  	int err;
  	struct inode *inode;
  	struct super_block *s = dir->i_sb;
  	struct bfs_sb_info *info = BFS_SB(s);
  	unsigned long ino;
  
  	inode = new_inode(s);
  	if (!inode)
  		return -ENOSPC;
  	mutex_lock(&info->bfs_lock);
  	ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1);
  	if (ino > info->si_lasti) {
  		mutex_unlock(&info->bfs_lock);
  		iput(inode);
  		return -ENOSPC;
  	}
  	set_bit(ino, info->si_imap);
  	info->si_freei--;
  	inode_init_owner(inode, dir, mode);
  	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
  	inode->i_blocks = 0;
  	inode->i_op = &bfs_file_inops;
  	inode->i_fop = &bfs_file_operations;
  	inode->i_mapping->a_ops = &bfs_aops;
  	inode->i_ino = ino;
  	BFS_I(inode)->i_dsk_ino = ino;
  	BFS_I(inode)->i_sblock = 0;
  	BFS_I(inode)->i_eblock = 0;
  	insert_inode_hash(inode);
          mark_inode_dirty(inode);
  	dump_imap("create", s);
  
  	err = bfs_add_entry(dir, dentry->d_name.name, dentry->d_name.len,
  							inode->i_ino);
  	if (err) {
  		inode_dec_link_count(inode);
  		mutex_unlock(&info->bfs_lock);
  		iput(inode);
  		return err;
  	}
  	mutex_unlock(&info->bfs_lock);
  	d_instantiate(dentry, inode);
  	return 0;
  }
  
  static struct dentry *bfs_lookup(struct inode *dir, struct dentry *dentry,
  						unsigned int flags)
  {
  	struct inode *inode = NULL;
  	struct buffer_head *bh;
  	struct bfs_dirent *de;
  	struct bfs_sb_info *info = BFS_SB(dir->i_sb);
  
  	if (dentry->d_name.len > BFS_NAMELEN)
  		return ERR_PTR(-ENAMETOOLONG);
  
  	mutex_lock(&info->bfs_lock);
  	bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
  	if (bh) {
  		unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
  		brelse(bh);
  		inode = bfs_iget(dir->i_sb, ino);
  		if (IS_ERR(inode)) {
  			mutex_unlock(&info->bfs_lock);
  			return ERR_CAST(inode);
  		}
  	}
  	mutex_unlock(&info->bfs_lock);
  	d_add(dentry, inode);
  	return NULL;
  }
  
  static int bfs_link(struct dentry *old, struct inode *dir,
  						struct dentry *new)
  {
  	struct inode *inode = old->d_inode;
  	struct bfs_sb_info *info = BFS_SB(inode->i_sb);
  	int err;
  
  	mutex_lock(&info->bfs_lock);
  	err = bfs_add_entry(dir, new->d_name.name, new->d_name.len,
  							inode->i_ino);
  	if (err) {
  		mutex_unlock(&info->bfs_lock);
  		return err;
  	}
  	inc_nlink(inode);
  	inode->i_ctime = CURRENT_TIME_SEC;
  	mark_inode_dirty(inode);
  	ihold(inode);
  	d_instantiate(new, inode);
  	mutex_unlock(&info->bfs_lock);
  	return 0;
  }
  
  static int bfs_unlink(struct inode *dir, struct dentry *dentry)
  {
  	int error = -ENOENT;
  	struct inode *inode = dentry->d_inode;
  	struct buffer_head *bh;
  	struct bfs_dirent *de;
  	struct bfs_sb_info *info = BFS_SB(inode->i_sb);
  
  	mutex_lock(&info->bfs_lock);
  	bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
  	if (!bh || (le16_to_cpu(de->ino) != inode->i_ino))
  		goto out_brelse;
  
  	if (!inode->i_nlink) {
  		printf("unlinking non-existent file %s:%lu (nlink=%d)
  ",
  					inode->i_sb->s_id, inode->i_ino,
  					inode->i_nlink);
  		set_nlink(inode, 1);
  	}
  	de->ino = 0;
  	mark_buffer_dirty_inode(bh, dir);
  	dir->i_ctime = dir->i_mtime = CURRENT_TIME_SEC;
  	mark_inode_dirty(dir);
  	inode->i_ctime = dir->i_ctime;
  	inode_dec_link_count(inode);
  	error = 0;
  
  out_brelse:
  	brelse(bh);
  	mutex_unlock(&info->bfs_lock);
  	return error;
  }
  
  static int bfs_rename(struct inode *old_dir, struct dentry *old_dentry,
  			struct inode *new_dir, struct dentry *new_dentry)
  {
  	struct inode *old_inode, *new_inode;
  	struct buffer_head *old_bh, *new_bh;
  	struct bfs_dirent *old_de, *new_de;
  	struct bfs_sb_info *info;
  	int error = -ENOENT;
  
  	old_bh = new_bh = NULL;
  	old_inode = old_dentry->d_inode;
  	if (S_ISDIR(old_inode->i_mode))
  		return -EINVAL;
  
  	info = BFS_SB(old_inode->i_sb);
  
  	mutex_lock(&info->bfs_lock);
  	old_bh = bfs_find_entry(old_dir, 
  				old_dentry->d_name.name, 
  				old_dentry->d_name.len, &old_de);
  
  	if (!old_bh || (le16_to_cpu(old_de->ino) != old_inode->i_ino))
  		goto end_rename;
  
  	error = -EPERM;
  	new_inode = new_dentry->d_inode;
  	new_bh = bfs_find_entry(new_dir, 
  				new_dentry->d_name.name, 
  				new_dentry->d_name.len, &new_de);
  
  	if (new_bh && !new_inode) {
  		brelse(new_bh);
  		new_bh = NULL;
  	}
  	if (!new_bh) {
  		error = bfs_add_entry(new_dir, 
  					new_dentry->d_name.name,
  					new_dentry->d_name.len,
  					old_inode->i_ino);
  		if (error)
  			goto end_rename;
  	}
  	old_de->ino = 0;
  	old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC;
  	mark_inode_dirty(old_dir);
  	if (new_inode) {
  		new_inode->i_ctime = CURRENT_TIME_SEC;
  		inode_dec_link_count(new_inode);
  	}
  	mark_buffer_dirty_inode(old_bh, old_dir);
  	error = 0;
  
  end_rename:
  	mutex_unlock(&info->bfs_lock);
  	brelse(old_bh);
  	brelse(new_bh);
  	return error;
  }
  
  const struct inode_operations bfs_dir_inops = {
  	.create			= bfs_create,
  	.lookup			= bfs_lookup,
  	.link			= bfs_link,
  	.unlink			= bfs_unlink,
  	.rename			= bfs_rename,
  };
  
  static int bfs_add_entry(struct inode *dir, const unsigned char *name,
  							int namelen, int ino)
  {
  	struct buffer_head *bh;
  	struct bfs_dirent *de;
  	int block, sblock, eblock, off, pos;
  	int i;
  
  	dprintf("name=%s, namelen=%d
  ", name, namelen);
  
  	if (!namelen)
  		return -ENOENT;
  	if (namelen > BFS_NAMELEN)
  		return -ENAMETOOLONG;
  
  	sblock = BFS_I(dir)->i_sblock;
  	eblock = BFS_I(dir)->i_eblock;
  	for (block = sblock; block <= eblock; block++) {
  		bh = sb_bread(dir->i_sb, block);
  		if (!bh)
  			return -ENOSPC;
  		for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) {
  			de = (struct bfs_dirent *)(bh->b_data + off);
  			if (!de->ino) {
  				pos = (block - sblock) * BFS_BSIZE + off;
  				if (pos >= dir->i_size) {
  					dir->i_size += BFS_DIRENT_SIZE;
  					dir->i_ctime = CURRENT_TIME_SEC;
  				}
  				dir->i_mtime = CURRENT_TIME_SEC;
  				mark_inode_dirty(dir);
  				de->ino = cpu_to_le16((u16)ino);
  				for (i = 0; i < BFS_NAMELEN; i++)
  					de->name[i] =
  						(i < namelen) ? name[i] : 0;
  				mark_buffer_dirty_inode(bh, dir);
  				brelse(bh);
  				return 0;
  			}
  		}
  		brelse(bh);
  	}
  	return -ENOSPC;
  }
  
  static inline int bfs_namecmp(int len, const unsigned char *name,
  							const char *buffer)
  {
  	if ((len < BFS_NAMELEN) && buffer[len])
  		return 0;
  	return !memcmp(name, buffer, len);
  }
  
  static struct buffer_head *bfs_find_entry(struct inode *dir,
  			const unsigned char *name, int namelen,
  			struct bfs_dirent **res_dir)
  {
  	unsigned long block = 0, offset = 0;
  	struct buffer_head *bh = NULL;
  	struct bfs_dirent *de;
  
  	*res_dir = NULL;
  	if (namelen > BFS_NAMELEN)
  		return NULL;
  
  	while (block * BFS_BSIZE + offset < dir->i_size) {
  		if (!bh) {
  			bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
  			if (!bh) {
  				block++;
  				continue;
  			}
  		}
  		de = (struct bfs_dirent *)(bh->b_data + offset);
  		offset += BFS_DIRENT_SIZE;
  		if (le16_to_cpu(de->ino) &&
  				bfs_namecmp(namelen, name, de->name)) {
  			*res_dir = de;
  			return bh;
  		}
  		if (offset < bh->b_size)
  			continue;
  		brelse(bh);
  		bh = NULL;
  		offset = 0;
  		block++;
  	}
  	brelse(bh);
  	return NULL;
  }