LXR linux/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
  18static int affs_readdir(struct file *, struct dir_context *);
  19
  20const 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 */
  30const 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
  42static int
  43affs_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;
 108inside:
 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        }
 131done:
 132        file->f_version = inode->i_version;
 133        file->private_data = (void *)(long)ino;
 134        affs_brelse(fh_bh);
 135
 136out_brelse_dir:
 137        affs_brelse(dir_bh);
 138
 139out_unlock_dir:
 140        affs_unlock_dir(inode);
 141        return error;
 142}
 143