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 *, struct dir_context *);
  19
  20 const struct file_operations affs_dir_operations = {
  21         .read           = generic_read_dir,
  22         .llseek         = generic_file_llseek,
  23         .iterate        = 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 *file, struct dir_context *ctx)
  44 {
  45         struct inode            *inode = file_inode(file);
  46         struct super_block      *sb = inode->i_sb;
  47         struct buffer_head      *dir_bh = NULL;
  48         struct buffer_head      *fh_bh = NULL;
  49         unsigned char           *name;
  50         int                      namelen;
  51         u32                      i;
  52         int                      hash_pos;
  53         int                      chain_pos;
  54         u32                      ino;
  55         int                      error = 0;
  56
  57         pr_debug("%s(ino=%lu,f_pos=%llx)\n", __func__, inode->i_ino, ctx->pos);
  58
  59         if (ctx->pos < 2) {
  60                 file->private_data = (void *)0;
  61                 if (!dir_emit_dots(file, ctx))
  62                         return 0;
  63         }
  64
  65         affs_lock_dir(inode);
  66         chain_pos = (ctx->pos - 2) & 0xffff;
  67         hash_pos  = (ctx->pos - 2) >> 16;
  68         if (chain_pos == 0xffff) {
  69                 affs_warning(sb, "readdir", "More than 65535 entries in chain");
  70                 chain_pos = 0;
  71                 hash_pos++;
  72                 ctx->pos = ((hash_pos << 16) | chain_pos) + 2;
  73         }
  74         dir_bh = affs_bread(sb, inode->i_ino);
  75         if (!dir_bh)
  76                 goto out_unlock_dir;
  77
  78         /* If the directory hasn't changed since the last call to readdir(),
  79          * we can jump directly to where we left off.
  80          */
  81         ino = (u32)(long)file->private_data;
  82         if (ino && file->f_version == inode->i_version) {
  83                 pr_debug("readdir() left off=%d\n", ino);
  84                 goto inside;
  85         }
  86
  87         ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
  88         for (i = 0; ino && i < chain_pos; i++) {
  89                 fh_bh = affs_bread(sb, ino);
  90                 if (!fh_bh) {
  91                         affs_error(sb, "readdir","Cannot read block %d", i);
  92                         error = -EIO;
  93                         goto out_brelse_dir;
  94                 }
  95                 ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
  96                 affs_brelse(fh_bh);
  97                 fh_bh = NULL;
  98         }
  99         if (ino)
 100                 goto inside;
 101         hash_pos++;
 102
 103         for (; hash_pos < AFFS_SB(sb)->s_hashsize; hash_pos++) {
 104                 ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
 105                 if (!ino)
 106                         continue;
 107                 ctx->pos = (hash_pos << 16) + 2;
 108 inside:
 109                 do {
 110                         fh_bh = affs_bread(sb, ino);
 111                         if (!fh_bh) {
 112                                 affs_error(sb, "readdir",
 113                                            "Cannot read block %d", ino);
 114                                 break;
 115                         }
 116
 117                         namelen = min(AFFS_TAIL(sb, fh_bh)->name[0],
 118                                       (u8)AFFSNAMEMAX);
 119                         name = AFFS_TAIL(sb, fh_bh)->name + 1;
 120                         pr_debug("readdir(): dir_emit(\"%.*s\", ino=%u), hash=%d, f_pos=%llx\n",
 121                                  namelen, name, ino, hash_pos, ctx->pos);
 122
 123                         if (!dir_emit(ctx, name, namelen, ino, DT_UNKNOWN))
 124                                 goto done;
 125                         ctx->pos++;
 126                         ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
 127                         affs_brelse(fh_bh);
 128                         fh_bh = NULL;
 129                 } while (ino);
 130         }
 131 done:
 132         file->f_version = inode->i_version;
 133         file->private_data = (void *)(long)ino;
 134         affs_brelse(fh_bh);
 135
 136 out_brelse_dir:
 137         affs_brelse(dir_bh);
 138
 139 out_unlock_dir:
 140         affs_unlock_dir(inode);
 141         return error;
 142 }