LXR linux/fs/efs/namei.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * namei.c
   4 *
   5 * Copyright (c) 1999 Al Smith
   6 *
   7 * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
   8 */
   9
  10#include <linux/buffer_head.h>
  11#include <linux/string.h>
  12#include <linux/exportfs.h>
  13#include "efs.h"
  14
  15
  16static efs_ino_t efs_find_entry(struct inode *inode, const char *name, int len)
  17{
  18        struct buffer_head *bh;
  19
  20        int                     slot, namelen;
  21        char                    *nameptr;
  22        struct efs_dir          *dirblock;
  23        struct efs_dentry       *dirslot;
  24        efs_ino_t               inodenum;
  25        efs_block_t             block;
  26 
  27        if (inode->i_size & (EFS_DIRBSIZE-1))
  28                pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE\n",
  29                        __func__);
  30
  31        for(block = 0; block < inode->i_blocks; block++) {
  32
  33                bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
  34                if (!bh) {
  35                        pr_err("%s(): failed to read dir block %d\n",
  36                               __func__, block);
  37                        return 0;
  38                }
  39    
  40                dirblock = (struct efs_dir *) bh->b_data;
  41
  42                if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
  43                        pr_err("%s(): invalid directory block\n", __func__);
  44                        brelse(bh);
  45                        return 0;
  46                }
  47
  48                for (slot = 0; slot < dirblock->slots; slot++) {
  49                        dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
  50
  51                        namelen  = dirslot->namelen;
  52                        nameptr  = dirslot->name;
  53
  54                        if ((namelen == len) && (!memcmp(name, nameptr, len))) {
  55                                inodenum = be32_to_cpu(dirslot->inode);
  56                                brelse(bh);
  57                                return inodenum;
  58                        }
  59                }
  60                brelse(bh);
  61        }
  62        return 0;
  63}
  64
  65struct dentry *efs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
  66{
  67        efs_ino_t inodenum;
  68        struct inode *inode = NULL;
  69
  70        inodenum = efs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
  71        if (inodenum)
  72                inode = efs_iget(dir->i_sb, inodenum);
  73
  74        return d_splice_alias(inode, dentry);
  75}
  76
  77static struct inode *efs_nfs_get_inode(struct super_block *sb, u64 ino,
  78                u32 generation)
  79{
  80        struct inode *inode;
  81
  82        if (ino == 0)
  83                return ERR_PTR(-ESTALE);
  84        inode = efs_iget(sb, ino);
  85        if (IS_ERR(inode))
  86                return ERR_CAST(inode);
  87
  88        if (generation && inode->i_generation != generation) {
  89                iput(inode);
  90                return ERR_PTR(-ESTALE);
  91        }
  92
  93        return inode;
  94}
  95
  96struct dentry *efs_fh_to_dentry(struct super_block *sb, struct fid *fid,
  97                int fh_len, int fh_type)
  98{
  99        return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
 100                                    efs_nfs_get_inode);
 101}
 102
 103struct dentry *efs_fh_to_parent(struct super_block *sb, struct fid *fid,
 104                int fh_len, int fh_type)
 105{
 106        return generic_fh_to_parent(sb, fid, fh_len, fh_type,
 107                                    efs_nfs_get_inode);
 108}
 109
 110struct dentry *efs_get_parent(struct dentry *child)
 111{
 112        struct dentry *parent = ERR_PTR(-ENOENT);
 113        efs_ino_t ino;
 114
 115        ino = efs_find_entry(d_inode(child), "..", 2);
 116        if (ino)
 117                parent = d_obtain_alias(efs_iget(child->d_sb, ino));
 118
 119        return parent;
 120}
 121