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 *, void *, filldir_t);
  19
  20const 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 */
  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 *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;
 123inside:
 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        }
 144readdir_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
 150readdir_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}
 157