fs/affs/dir.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/affs/dir.c
   4  *
   5  *  (c) 1996  Hans-Joachim Widmaier - Rewritten
   6  *
   7  *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
   8  *
   9  *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
  10  *
  11  *  (C) 1991  Linus Torvalds - minix filesystem
  12  *
  13  *  affs directory handling functions
  14  *
  15  */
  16
  17 #include "affs.h"
  18
  19 static int affs_readdir(struct file *, struct dir_context *);
  20
  21 const struct file_operations affs_dir_operations = {
  22         .read           = generic_read_dir,
  23         .llseek         = generic_file_llseek,
  24         .iterate_shared = affs_readdir,
  25         .fsync          = affs_file_fsync,
  26 };
  27
  28 /*
  29  * directories can handle most operations...
  30  */
  31 const struct inode_operations affs_dir_inode_operations = {
  32         .create         = affs_create,
  33         .lookup         = affs_lookup,
  34         .link           = affs_link,
  35         .unlink         = affs_unlink,
  36         .symlink        = affs_symlink,
  37         .mkdir          = affs_mkdir,
  38         .rmdir          = affs_rmdir,
  39         .rename         = affs_rename2,
  40         .setattr        = affs_notify_change,
  41 };
  42
  43 static int
  44 affs_readdir(struct file *file, struct dir_context *ctx)
  45 {
  46         struct inode            *inode = file_inode(file);
  47         struct super_block      *sb = inode->i_sb;
  48         struct buffer_head      *dir_bh = NULL;
  49         struct buffer_head      *fh_bh = NULL;
  50         unsigned char           *name;
  51         int                      namelen;
  52         u32                      i;
  53         int                      hash_pos;
  54         int                      chain_pos;
  55         u32                      ino;
  56         int                      error = 0;
  57
  58         pr_debug("%s(ino=%lu,f_pos=%llx)\n", __func__, inode->i_ino, ctx->pos);
  59
  60         if (ctx->pos < 2) {
  61                 file->private_data = (void *)0;
  62                 if (!dir_emit_dots(file, ctx))
  63                         return 0;
  64         }
  65
  66         affs_lock_dir(inode);
  67         chain_pos = (ctx->pos - 2) & 0xffff;
  68         hash_pos  = (ctx->pos - 2) >> 16;
  69         if (chain_pos == 0xffff) {
  70                 affs_warning(sb, "readdir", "More than 65535 entries in chain");
  71                 chain_pos = 0;
  72                 hash_pos++;
  73                 ctx->pos = ((hash_pos << 16) | chain_pos) + 2;
  74         }
  75         dir_bh = affs_bread(sb, inode->i_ino);
  76         if (!dir_bh)
  77                 goto out_unlock_dir;
  78
  79         /* If the directory hasn't changed since the last call to readdir(),
  80          * we can jump directly to where we left off.
  81          */
  82         ino = (u32)(long)file->private_data;
  83         if (ino && file->f_version == inode->i_version) {
  84                 pr_debug("readdir() left off=%d\n", ino);
  85                 goto inside;
  86         }
  87
  88         ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
  89         for (i = 0; ino && i < chain_pos; i++) {
  90                 fh_bh = affs_bread(sb, ino);
  91                 if (!fh_bh) {
  92                         affs_error(sb, "readdir","Cannot read block %d", i);
  93                         error = -EIO;
  94                         goto out_brelse_dir;
  95                 }
  96                 ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
  97                 affs_brelse(fh_bh);
  98                 fh_bh = NULL;
  99         }
 100         if (ino)
 101                 goto inside;
 102         hash_pos++;
 103
 104         for (; hash_pos < AFFS_SB(sb)->s_hashsize; hash_pos++) {
 105                 ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
 106                 if (!ino)
 107                         continue;
 108                 ctx->pos = (hash_pos << 16) + 2;
 109 inside:
 110                 do {
 111                         fh_bh = affs_bread(sb, ino);
 112                         if (!fh_bh) {
 113                                 affs_error(sb, "readdir",
 114                                            "Cannot read block %d", ino);
 115                                 break;
 116                         }
 117
 118                         namelen = min(AFFS_TAIL(sb, fh_bh)->name[0],
 119                                       (u8)AFFSNAMEMAX);
 120                         name = AFFS_TAIL(sb, fh_bh)->name + 1;
 121                         pr_debug("readdir(): dir_emit(\"%.*s\", ino=%u), hash=%d, f_pos=%llx\n",
 122                                  namelen, name, ino, hash_pos, ctx->pos);
 123
 124                         if (!dir_emit(ctx, name, namelen, ino, DT_UNKNOWN))
 125                                 goto done;
 126                         ctx->pos++;
 127                         ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
 128                         affs_brelse(fh_bh);
 129                         fh_bh = NULL;
 130                 } while (ino);
 131         }
 132 done:
 133         file->f_version = inode->i_version;
 134         file->private_data = (void *)(long)ino;
 135         affs_brelse(fh_bh);
 136
 137 out_brelse_dir:
 138         affs_brelse(dir_bh);
 139
 140 out_unlock_dir:
 141         affs_unlock_dir(inode);
 142         return error;
 143 }