LXR linux/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 <linux/iversion.h>
  18#include "affs.h"
  19
  20static int affs_readdir(struct file *, struct dir_context *);
  21
  22const struct file_operations affs_dir_operations = {
  23        .read           = generic_read_dir,
  24        .llseek         = generic_file_llseek,
  25        .iterate_shared = affs_readdir,
  26        .fsync          = affs_file_fsync,
  27};
  28
  29/*
  30 * directories can handle most operations...
  31 */
  32const struct inode_operations affs_dir_inode_operations = {
  33        .create         = affs_create,
  34        .lookup         = affs_lookup,
  35        .link           = affs_link,
  36        .unlink         = affs_unlink,
  37        .symlink        = affs_symlink,
  38        .mkdir          = affs_mkdir,
  39        .rmdir          = affs_rmdir,
  40        .rename         = affs_rename2,
  41        .setattr        = affs_notify_change,
  42};
  43
  44static int
  45affs_readdir(struct file *file, struct dir_context *ctx)
  46{
  47        struct inode            *inode = file_inode(file);
  48        struct super_block      *sb = inode->i_sb;
  49        struct buffer_head      *dir_bh = NULL;
  50        struct buffer_head      *fh_bh = NULL;
  51        unsigned char           *name;
  52        int                      namelen;
  53        u32                      i;
  54        int                      hash_pos;
  55        int                      chain_pos;
  56        u32                      ino;
  57        int                      error = 0;
  58
  59        pr_debug("%s(ino=%lu,f_pos=%llx)\n", __func__, inode->i_ino, ctx->pos);
  60
  61        if (ctx->pos < 2) {
  62                file->private_data = (void *)0;
  63                if (!dir_emit_dots(file, ctx))
  64                        return 0;
  65        }
  66
  67        affs_lock_dir(inode);
  68        chain_pos = (ctx->pos - 2) & 0xffff;
  69        hash_pos  = (ctx->pos - 2) >> 16;
  70        if (chain_pos == 0xffff) {
  71                affs_warning(sb, "readdir", "More than 65535 entries in chain");
  72                chain_pos = 0;
  73                hash_pos++;
  74                ctx->pos = ((hash_pos << 16) | chain_pos) + 2;
  75        }
  76        dir_bh = affs_bread(sb, inode->i_ino);
  77        if (!dir_bh)
  78                goto out_unlock_dir;
  79
  80        /* If the directory hasn't changed since the last call to readdir(),
  81         * we can jump directly to where we left off.
  82         */
  83        ino = (u32)(long)file->private_data;
  84        if (ino && inode_eq_iversion(inode, file->f_version)) {
  85                pr_debug("readdir() left off=%d\n", ino);
  86                goto inside;
  87        }
  88
  89        ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
  90        for (i = 0; ino && i < chain_pos; i++) {
  91                fh_bh = affs_bread(sb, ino);
  92                if (!fh_bh) {
  93                        affs_error(sb, "readdir","Cannot read block %d", i);
  94                        error = -EIO;
  95                        goto out_brelse_dir;
  96                }
  97                ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
  98                affs_brelse(fh_bh);
  99                fh_bh = NULL;
 100        }
 101        if (ino)
 102                goto inside;
 103        hash_pos++;
 104
 105        for (; hash_pos < AFFS_SB(sb)->s_hashsize; hash_pos++) {
 106                ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
 107                if (!ino)
 108                        continue;
 109                ctx->pos = (hash_pos << 16) + 2;
 110inside:
 111                do {
 112                        fh_bh = affs_bread(sb, ino);
 113                        if (!fh_bh) {
 114                                affs_error(sb, "readdir",
 115                                           "Cannot read block %d", ino);
 116                                break;
 117                        }
 118
 119                        namelen = min(AFFS_TAIL(sb, fh_bh)->name[0],
 120                                      (u8)AFFSNAMEMAX);
 121                        name = AFFS_TAIL(sb, fh_bh)->name + 1;
 122                        pr_debug("readdir(): dir_emit(\"%.*s\", ino=%u), hash=%d, f_pos=%llx\n",
 123                                 namelen, name, ino, hash_pos, ctx->pos);
 124
 125                        if (!dir_emit(ctx, name, namelen, ino, DT_UNKNOWN))
 126                                goto done;
 127                        ctx->pos++;
 128                        ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
 129                        affs_brelse(fh_bh);
 130                        fh_bh = NULL;
 131                } while (ino);
 132        }
 133done:
 134        file->f_version = inode_query_iversion(inode);
 135        file->private_data = (void *)(long)ino;
 136        affs_brelse(fh_bh);
 137
 138out_brelse_dir:
 139        affs_brelse(dir_bh);
 140
 141out_unlock_dir:
 142        affs_unlock_dir(inode);
 143        return error;
 144}
 145