text: /*
   * namei.c
   *
   * Copyright (c) 1999 Al Smith
   *
   * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
   */
  
  #include <linux/buffer_head.h>
  #include <linux/string.h>
  #include <linux/exportfs.h>
  #include "efs.h"
  
  
  static efs_ino_t efs_find_entry(struct inode *inode, const char *name, int len) {
  	struct buffer_head *bh;
  
  	int			slot, namelen;
  	char			*nameptr;
  	struct efs_dir		*dirblock;
  	struct efs_dentry	*dirslot;
  	efs_ino_t		inodenum;
  	efs_block_t		block;
   
  	if (inode->i_size & (EFS_DIRBSIZE-1))
  		pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE\n",
  			__func__);
  
  	for(block = 0; block < inode->i_blocks; block++) {
  
  		bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
  		if (!bh) {
  			pr_err("%s(): failed to read dir block %d\n",
  			       __func__, block);
  			return 0;
  		}
      
  		dirblock = (struct efs_dir *) bh->b_data;
  
  		if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
  			pr_err("%s(): invalid directory block\n", __func__);
  			brelse(bh);
  			return(0);
  		}
  
  		for(slot = 0; slot < dirblock->slots; slot++) {
  			dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
  
  			namelen  = dirslot->namelen;
  			nameptr  = dirslot->name;
  
  			if ((namelen == len) && (!memcmp(name, nameptr, len))) {
  				inodenum = be32_to_cpu(dirslot->inode);
  				brelse(bh);
  				return(inodenum);
  			}
  		}
  		brelse(bh);
  	}
  	return(0);
  }
  
  struct dentry *efs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
  {
  	efs_ino_t inodenum;
  	struct inode *inode = NULL;
  
  	inodenum = efs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
  	if (inodenum)
  		inode = efs_iget(dir->i_sb, inodenum);
  
  	return d_splice_alias(inode, dentry);
  }
  
  static struct inode *efs_nfs_get_inode(struct super_block *sb, u64 ino,
  		u32 generation)
  {
  	struct inode *inode;
  
  	if (ino == 0)
  		return ERR_PTR(-ESTALE);
  	inode = efs_iget(sb, ino);
  	if (IS_ERR(inode))
  		return ERR_CAST(inode);
  
  	if (generation && inode->i_generation != generation) {
  		iput(inode);
  		return ERR_PTR(-ESTALE);
  	}
  
  	return inode;
  }
  
  struct dentry *efs_fh_to_dentry(struct super_block *sb, struct fid *fid,
  		int fh_len, int fh_type)
  {
  	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
  				    efs_nfs_get_inode);
  }
  
  struct dentry *efs_fh_to_parent(struct super_block *sb, struct fid *fid,
  		int fh_len, int fh_type)
  {
  	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
  				    efs_nfs_get_inode);
  }
  
  struct dentry *efs_get_parent(struct dentry *child)
  {
  	struct dentry *parent = ERR_PTR(-ENOENT);
  	efs_ino_t ino;
  
  	ino = efs_find_entry(child->d_inode, "..", 2);
  	if (ino)
  		parent = d_obtain_alias(efs_iget(child->d_inode->i_sb, ino));
  
  	return parent;
  }
  