fs/affs/dir.c

   1 /*
   2  *  linux/fs/affs/dir.c
   3  *
   4  *  (c) 1996  Hans-Joachim Widmaier - Rewritten
   5  *
   6  *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
   7  *
   8  *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
   9  *
  10  *  (C) 1991  Linus Torvalds - minix filesystem
  11  *
  12  *  affs directory handling functions
  13  *
  14  */
  15
  16 #include "affs.h"
  17
  18 static int affs_readdir(struct file *, void *, filldir_t);
  19
  20 const struct file_operations affs_dir_operations = {
  21         .read           = generic_read_dir,
  22         .readdir        = affs_readdir,
  23         .fsync          = file_fsync,
  24 };
  25
  26 /*
  27  * directories can handle most operations...
  28  */
  29 struct inode_operations affs_dir_inode_operations = {
  30         .create         = affs_create,
  31         .lookup         = affs_lookup,
  32         .link           = affs_link,
  33         .unlink         = affs_unlink,
  34         .symlink        = affs_symlink,
  35         .mkdir          = affs_mkdir,
  36         .rmdir          = affs_rmdir,
  37         .rename         = affs_rename,
  38         .setattr        = affs_notify_change,
  39 };
  40
  41 static int
  42 affs_readdir(struct file *filp, void *dirent, filldir_t filldir)
  43 {
  44         struct inode            *inode = filp->f_dentry->d_inode;
  45         struct super_block      *sb = inode->i_sb;
  46         struct buffer_head      *dir_bh;
  47         struct buffer_head      *fh_bh;
  48         unsigned char           *name;
  49         int                      namelen;
  50         u32                      i;
  51         int                      hash_pos;
  52         int                      chain_pos;
  53         u32                      f_pos;
  54         u32                      ino;
  55         int                      stored;
  56         int                      res;
  57
  58         pr_debug("AFFS: readdir(ino=%lu,f_pos=%lx)\n",inode->i_ino,(unsigned long)filp->f_pos);
  59
  60         stored = 0;
  61         res    = -EIO;
  62         dir_bh = NULL;
  63         fh_bh  = NULL;
  64         f_pos  = filp->f_pos;
  65
  66         if (f_pos == 0) {
  67                 filp->private_data = (void *)0;
  68                 if (filldir(dirent, ".", 1, f_pos, inode->i_ino, DT_DIR) < 0)
  69                         return 0;
  70                 filp->f_pos = f_pos = 1;
  71                 stored++;
  72         }
  73         if (f_pos == 1) {
  74                 if (filldir(dirent, "..", 2, f_pos, parent_ino(filp->f_dentry), DT_DIR) < 0)
  75                         return stored;
  76                 filp->f_pos = f_pos = 2;
  77                 stored++;
  78         }
  79
  80         affs_lock_dir(inode);
  81         chain_pos = (f_pos - 2) & 0xffff;
  82         hash_pos  = (f_pos - 2) >> 16;
  83         if (chain_pos == 0xffff) {
  84                 affs_warning(sb, "readdir", "More than 65535 entries in chain");
  85                 chain_pos = 0;
  86                 hash_pos++;
  87                 filp->f_pos = ((hash_pos << 16) | chain_pos) + 2;
  88         }
  89         dir_bh = affs_bread(sb, inode->i_ino);
  90         if (!dir_bh)
  91                 goto readdir_out;
  92
  93         /* If the directory hasn't changed since the last call to readdir(),
  94          * we can jump directly to where we left off.
  95          */
  96         ino = (u32)(long)filp->private_data;
  97         if (ino && filp->f_version == inode->i_version) {
  98                 pr_debug("AFFS: readdir() left off=%d\n", ino);
  99                 goto inside;
 100         }
 101
 102         ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
 103         for (i = 0; ino && i < chain_pos; i++) {
 104                 fh_bh = affs_bread(sb, ino);
 105                 if (!fh_bh) {
 106                         affs_error(sb, "readdir","Cannot read block %d", i);
 107                         goto readdir_out;
 108                 }
 109                 ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
 110                 affs_brelse(fh_bh);
 111                 fh_bh = NULL;
 112         }
 113         if (ino)
 114                 goto inside;
 115         hash_pos++;
 116
 117         for (; hash_pos < AFFS_SB(sb)->s_hashsize; hash_pos++) {
 118                 ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
 119                 if (!ino)
 120                         continue;
 121                 f_pos = (hash_pos << 16) + 2;
 122 inside:
 123                 do {
 124                         fh_bh = affs_bread(sb, ino);
 125                         if (!fh_bh) {
 126                                 affs_error(sb, "readdir","Cannot read block %d", ino);
 127                                 goto readdir_done;
 128                         }
 129
 130                         namelen = min(AFFS_TAIL(sb, fh_bh)->name[0], (u8)30);
 131                         name = AFFS_TAIL(sb, fh_bh)->name + 1;
 132                         pr_debug("AFFS: readdir(): filldir(\"%.*s\", ino=%u), hash=%d, f_pos=%x\n",
 133                                  namelen, name, ino, hash_pos, f_pos);
 134                         if (filldir(dirent, name, namelen, f_pos, ino, DT_UNKNOWN) < 0)
 135                                 goto readdir_done;
 136                         stored++;
 137                         f_pos++;
 138                         ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
 139                         affs_brelse(fh_bh);
 140                         fh_bh = NULL;
 141                 } while (ino);
 142         }
 143 readdir_done:
 144         filp->f_pos = f_pos;
 145         filp->f_version = inode->i_version;
 146         filp->private_data = (void *)(long)ino;
 147         res = stored;
 148
 149 readdir_out:
 150         affs_brelse(dir_bh);
 151         affs_brelse(fh_bh);
 152         affs_unlock_dir(inode);
 153         pr_debug("AFFS: readdir()=%d\n", stored);
 154         return res;
 155 }