fs/efs/dir.c

   1 /*
   2  * dir.c
   3  *
   4  * Copyright (c) 1999 Al Smith
   5  */
   6
   7 #include <linux/buffer_head.h>
   8 #include "efs.h"
   9
  10 static int efs_readdir(struct file *, void *, filldir_t);
  11
  12 const struct file_operations efs_dir_operations = {
  13         .llseek         = generic_file_llseek,
  14         .read           = generic_read_dir,
  15         .readdir        = efs_readdir,
  16 };
  17
  18 const struct inode_operations efs_dir_inode_operations = {
  19         .lookup         = efs_lookup,
  20 };
  21
  22 static int efs_readdir(struct file *filp, void *dirent, filldir_t filldir) {
  23         struct inode *inode = file_inode(filp);
  24         struct buffer_head *bh;
  25
  26         struct efs_dir          *dirblock;
  27         struct efs_dentry       *dirslot;
  28         efs_ino_t               inodenum;
  29         efs_block_t             block;
  30         int                     slot, namelen;
  31         char                    *nameptr;
  32
  33         if (inode->i_size & (EFS_DIRBSIZE-1))
  34                 printk(KERN_WARNING "EFS: WARNING: readdir(): directory size not a multiple of EFS_DIRBSIZE\n");
  35
  36         /* work out where this entry can be found */
  37         block = filp->f_pos >> EFS_DIRBSIZE_BITS;
  38
  39         /* each block contains at most 256 slots */
  40         slot  = filp->f_pos & 0xff;
  41
  42         /* look at all blocks */
  43         while (block < inode->i_blocks) {
  44                 /* read the dir block */
  45                 bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
  46
  47                 if (!bh) {
  48                         printk(KERN_ERR "EFS: readdir(): failed to read dir block %d\n", block);
  49                         break;
  50                 }
  51
  52                 dirblock = (struct efs_dir *) bh->b_data;
  53
  54                 if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
  55                         printk(KERN_ERR "EFS: readdir(): invalid directory block\n");
  56                         brelse(bh);
  57                         break;
  58                 }
  59
  60                 while (slot < dirblock->slots) {
  61                         if (dirblock->space[slot] == 0) {
  62                                 slot++;
  63                                 continue;
  64                         }
  65
  66                         dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
  67
  68                         inodenum = be32_to_cpu(dirslot->inode);
  69                         namelen  = dirslot->namelen;
  70                         nameptr  = dirslot->name;
  71
  72 #ifdef DEBUG
  73                         printk(KERN_DEBUG "EFS: readdir(): block %d slot %d/%d: inode %u, name \"%s\", namelen %u\n", block, slot, dirblock->slots-1, inodenum, nameptr, namelen);
  74 #endif
  75                         if (namelen > 0) {
  76                                 /* found the next entry */
  77                                 filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;
  78
  79                                 /* copy filename and data in dirslot */
  80                                 filldir(dirent, nameptr, namelen, filp->f_pos, inodenum, DT_UNKNOWN);
  81
  82                                 /* sanity check */
  83                                 if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) {
  84                                         printk(KERN_WARNING "EFS: directory entry %d exceeds directory block\n", slot);
  85                                         slot++;
  86                                         continue;
  87                                 }
  88
  89                                 /* store position of next slot */
  90                                 if (++slot == dirblock->slots) {
  91                                         slot = 0;
  92                                         block++;
  93                                 }
  94                                 brelse(bh);
  95                                 filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;
  96                                 goto out;
  97                         }
  98                         slot++;
  99                 }
 100                 brelse(bh);
 101
 102                 slot = 0;
 103                 block++;
 104         }
 105
 106         filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;
 107 out:
 108         return 0;
 109 }
 110