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 <linux/smp_lock.h>
   9 #include "efs.h"
  10
  11 static int efs_readdir(struct file *, void *, filldir_t);
  12
  13 const struct file_operations efs_dir_operations = {
  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 = filp->f_path.dentry->d_inode;
  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         lock_kernel();
  37
  38         /* work out where this entry can be found */
  39         block = filp->f_pos >> EFS_DIRBSIZE_BITS;
  40
  41         /* each block contains at most 256 slots */
  42         slot  = filp->f_pos & 0xff;
  43
  44         /* look at all blocks */
  45         while (block < inode->i_blocks) {
  46                 /* read the dir block */
  47                 bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
  48
  49                 if (!bh) {
  50                         printk(KERN_ERR "EFS: readdir(): failed to read dir block %d\n", block);
  51                         break;
  52                 }
  53
  54                 dirblock = (struct efs_dir *) bh->b_data;
  55
  56                 if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
  57                         printk(KERN_ERR "EFS: readdir(): invalid directory block\n");
  58                         brelse(bh);
  59                         break;
  60                 }
  61
  62                 while (slot < dirblock->slots) {
  63                         if (dirblock->space[slot] == 0) {
  64                                 slot++;
  65                                 continue;
  66                         }
  67
  68                         dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
  69
  70                         inodenum = be32_to_cpu(dirslot->inode);
  71                         namelen  = dirslot->namelen;
  72                         nameptr  = dirslot->name;
  73
  74 #ifdef DEBUG
  75                         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);
  76 #endif
  77                         if (namelen > 0) {
  78                                 /* found the next entry */
  79                                 filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;
  80
  81                                 /* copy filename and data in dirslot */
  82                                 filldir(dirent, nameptr, namelen, filp->f_pos, inodenum, DT_UNKNOWN);
  83
  84                                 /* sanity check */
  85                                 if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) {
  86                                         printk(KERN_WARNING "EFS: directory entry %d exceeds directory block\n", slot);
  87                                         slot++;
  88                                         continue;
  89                                 }
  90
  91                                 /* store position of next slot */
  92                                 if (++slot == dirblock->slots) {
  93                                         slot = 0;
  94                                         block++;
  95                                 }
  96                                 brelse(bh);
  97                                 filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;
  98                                 goto out;
  99                         }
 100                         slot++;
 101                 }
 102                 brelse(bh);
 103
 104                 slot = 0;
 105                 block++;
 106         }
 107
 108         filp->f_pos = (block << EFS_DIRBSIZE_BITS) | slot;
 109 out:
 110         unlock_kernel();
 111         return 0;
 112 }
 113