linux/fs/affs/dir.c
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   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
  56        pr_debug("AFFS: readdir(ino=%lu,f_pos=%lx)\n",inode->i_ino,(unsigned long)ctx->pos);
  57
  58        if (ctx->pos < 2) {
  59                file->private_data = (void *)0;
  60                if (!dir_emit_dots(file, ctx))
  61                        return 0;
  62        }
  63
  64        affs_lock_dir(inode);
  65        chain_pos = (ctx->pos - 2) & 0xffff;
  66        hash_pos  = (ctx->pos - 2) >> 16;
  67        if (chain_pos == 0xffff) {
  68                affs_warning(sb, "readdir", "More than 65535 entries in chain");
  69                chain_pos = 0;
  70                hash_pos++;
  71                ctx->pos = ((hash_pos << 16) | chain_pos) + 2;
  72        }
  73        dir_bh = affs_bread(sb, inode->i_ino);
  74        if (!dir_bh)
  75                goto readdir_out;
  76
  77        /* If the directory hasn't changed since the last call to readdir(),
  78         * we can jump directly to where we left off.
  79         */
  80        ino = (u32)(long)file->private_data;
  81        if (ino && file->f_version == inode->i_version) {
  82                pr_debug("AFFS: readdir() left off=%d\n", ino);
  83                goto inside;
  84        }
  85
  86        ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
  87        for (i = 0; ino && i < chain_pos; i++) {
  88                fh_bh = affs_bread(sb, ino);
  89                if (!fh_bh) {
  90                        affs_error(sb, "readdir","Cannot read block %d", i);
  91                        return -EIO;
  92                }
  93                ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
  94                affs_brelse(fh_bh);
  95                fh_bh = NULL;
  96        }
  97        if (ino)
  98                goto inside;
  99        hash_pos++;
 100
 101        for (; hash_pos < AFFS_SB(sb)->s_hashsize; hash_pos++) {
 102                ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
 103                if (!ino)
 104                        continue;
 105                ctx->pos = (hash_pos << 16) + 2;
 106inside:
 107                do {
 108                        fh_bh = affs_bread(sb, ino);
 109                        if (!fh_bh) {
 110                                affs_error(sb, "readdir","Cannot read block %d", ino);
 111                                break;
 112                        }
 113
 114                        namelen = min(AFFS_TAIL(sb, fh_bh)->name[0], (u8)30);
 115                        name = AFFS_TAIL(sb, fh_bh)->name + 1;
 116                        pr_debug("AFFS: readdir(): filldir(\"%.*s\", ino=%u), hash=%d, f_pos=%x\n",
 117                                 namelen, name, ino, hash_pos, (u32)ctx->pos);
 118                        if (!dir_emit(ctx, name, namelen, ino, DT_UNKNOWN))
 119                                goto readdir_done;
 120                        ctx->pos++;
 121                        ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
 122                        affs_brelse(fh_bh);
 123                        fh_bh = NULL;
 124                } while (ino);
 125        }
 126readdir_done:
 127        file->f_version = inode->i_version;
 128        file->private_data = (void *)(long)ino;
 129
 130readdir_out:
 131        affs_brelse(dir_bh);
 132        affs_brelse(fh_bh);
 133        affs_unlock_dir(inode);
 134        return 0;
 135}
 136
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