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         .llseek         = generic_file_llseek,
  23         .readdir        = affs_readdir,
  24         .fsync          = affs_file_fsync,
  25 };
  26
  27 /*
  28  * directories can handle most operations...
  29  */
  30 const struct inode_operations affs_dir_inode_operations = {
  31         .create         = affs_create,
  32         .lookup         = affs_lookup,
  33         .link           = affs_link,
  34         .unlink         = affs_unlink,
  35         .symlink        = affs_symlink,
  36         .mkdir          = affs_mkdir,
  37         .rmdir          = affs_rmdir,
  38         .rename         = affs_rename,
  39         .setattr        = affs_notify_change,
  40 };
  41
  42 static int
  43 affs_readdir(struct file *filp, void *dirent, filldir_t filldir)
  44 {
  45         struct inode            *inode = filp->f_path.dentry->d_inode;
  46         struct super_block      *sb = inode->i_sb;
  47         struct buffer_head      *dir_bh;
  48         struct buffer_head      *fh_bh;
  49         unsigned char           *name;
  50         int                      namelen;
  51         u32                      i;
  52         int                      hash_pos;
  53         int                      chain_pos;
  54         u32                      f_pos;
  55         u32                      ino;
  56         int                      stored;
  57         int                      res;
  58
  59         pr_debug("AFFS: readdir(ino=%lu,f_pos=%lx)\n",inode->i_ino,(unsigned long)filp->f_pos);
  60
  61         stored = 0;
  62         res    = -EIO;
  63         dir_bh = NULL;
  64         fh_bh  = NULL;
  65         f_pos  = filp->f_pos;
  66
  67         if (f_pos == 0) {
  68                 filp->private_data = (void *)0;
  69                 if (filldir(dirent, ".", 1, f_pos, inode->i_ino, DT_DIR) < 0)
  70                         return 0;
  71                 filp->f_pos = f_pos = 1;
  72                 stored++;
  73         }
  74         if (f_pos == 1) {
  75                 if (filldir(dirent, "..", 2, f_pos, parent_ino(filp->f_path.dentry), DT_DIR) < 0)
  76                         return stored;
  77                 filp->f_pos = f_pos = 2;
  78                 stored++;
  79         }
  80
  81         affs_lock_dir(inode);
  82         chain_pos = (f_pos - 2) & 0xffff;
  83         hash_pos  = (f_pos - 2) >> 16;
  84         if (chain_pos == 0xffff) {
  85                 affs_warning(sb, "readdir", "More than 65535 entries in chain");
  86                 chain_pos = 0;
  87                 hash_pos++;
  88                 filp->f_pos = ((hash_pos << 16) | chain_pos) + 2;
  89         }
  90         dir_bh = affs_bread(sb, inode->i_ino);
  91         if (!dir_bh)
  92                 goto readdir_out;
  93
  94         /* If the directory hasn't changed since the last call to readdir(),
  95          * we can jump directly to where we left off.
  96          */
  97         ino = (u32)(long)filp->private_data;
  98         if (ino && filp->f_version == inode->i_version) {
  99                 pr_debug("AFFS: readdir() left off=%d\n", ino);
 100                 goto inside;
 101         }
 102
 103         ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
 104         for (i = 0; ino && i < chain_pos; i++) {
 105                 fh_bh = affs_bread(sb, ino);
 106                 if (!fh_bh) {
 107                         affs_error(sb, "readdir","Cannot read block %d", i);
 108                         goto readdir_out;
 109                 }
 110                 ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
 111                 affs_brelse(fh_bh);
 112                 fh_bh = NULL;
 113         }
 114         if (ino)
 115                 goto inside;
 116         hash_pos++;
 117
 118         for (; hash_pos < AFFS_SB(sb)->s_hashsize; hash_pos++) {
 119                 ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
 120                 if (!ino)
 121                         continue;
 122                 f_pos = (hash_pos << 16) + 2;
 123 inside:
 124                 do {
 125                         fh_bh = affs_bread(sb, ino);
 126                         if (!fh_bh) {
 127                                 affs_error(sb, "readdir","Cannot read block %d", ino);
 128                                 goto readdir_done;
 129                         }
 130
 131                         namelen = min(AFFS_TAIL(sb, fh_bh)->name[0], (u8)30);
 132                         name = AFFS_TAIL(sb, fh_bh)->name + 1;
 133                         pr_debug("AFFS: readdir(): filldir(\"%.*s\", ino=%u), hash=%d, f_pos=%x\n",
 134                                  namelen, name, ino, hash_pos, f_pos);
 135                         if (filldir(dirent, name, namelen, f_pos, ino, DT_UNKNOWN) < 0)
 136                                 goto readdir_done;
 137                         stored++;
 138                         f_pos++;
 139                         ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
 140                         affs_brelse(fh_bh);
 141                         fh_bh = NULL;
 142                 } while (ino);
 143         }
 144 readdir_done:
 145         filp->f_pos = f_pos;
 146         filp->f_version = inode->i_version;
 147         filp->private_data = (void *)(long)ino;
 148         res = stored;
 149
 150 readdir_out:
 151         affs_brelse(dir_bh);
 152         affs_brelse(fh_bh);
 153         affs_unlock_dir(inode);
 154         pr_debug("AFFS: readdir()=%d\n", stored);
 155         return res;
 156 }