original development tree for Linux kernel GTP module; now long in mainline.
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/*
* linux/fs/affs/dir.c
*
* (c) 1996 Hans-Joachim Widmaier - Rewritten
*
* (C) 1993 Ray Burr - Modified for Amiga FFS filesystem.
*
* (C) 1992 Eric Youngdale Modified for ISO 9660 filesystem.
*
* (C) 1991 Linus Torvalds - minix filesystem
*
* affs directory handling functions
*
*/
#include "affs.h"
static int affs_readdir(struct file *, struct dir_context *);
const struct file_operations affs_dir_operations = {
.read = generic_read_dir,
.llseek = generic_file_llseek,
.iterate = affs_readdir,
.fsync = affs_file_fsync,
};
/*
* directories can handle most operations...
*/
const struct inode_operations affs_dir_inode_operations = {
.create = affs_create,
.lookup = affs_lookup,
.link = affs_link,
.unlink = affs_unlink,
.symlink = affs_symlink,
.mkdir = affs_mkdir,
.rmdir = affs_rmdir,
.rename = affs_rename,
.setattr = affs_notify_change,
};
static int
affs_readdir(struct file *file, struct dir_context *ctx)
{
struct inode *inode = file_inode(file);
struct super_block *sb = inode->i_sb;
struct buffer_head *dir_bh = NULL;
struct buffer_head *fh_bh = NULL;
unsigned char *name;
int namelen;
u32 i;
int hash_pos;
int chain_pos;
u32 ino;
pr_debug("AFFS: readdir(ino=%lu,f_pos=%lx)\n",inode->i_ino,(unsigned long)ctx->pos);
if (ctx->pos < 2) {
file->private_data = (void *)0;
if (!dir_emit_dots(file, ctx))
return 0;
}
affs_lock_dir(inode);
chain_pos = (ctx->pos - 2) & 0xffff;
hash_pos = (ctx->pos - 2) >> 16;
if (chain_pos == 0xffff) {
affs_warning(sb, "readdir", "More than 65535 entries in chain");
chain_pos = 0;
hash_pos++;
ctx->pos = ((hash_pos << 16) | chain_pos) + 2;
}
dir_bh = affs_bread(sb, inode->i_ino);
if (!dir_bh)
goto readdir_out;
/* If the directory hasn't changed since the last call to readdir(),
* we can jump directly to where we left off.
*/
ino = (u32)(long)file->private_data;
if (ino && file->f_version == inode->i_version) {
pr_debug("AFFS: readdir() left off=%d\n", ino);
goto inside;
}
ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
for (i = 0; ino && i < chain_pos; i++) {
fh_bh = affs_bread(sb, ino);
if (!fh_bh) {
affs_error(sb, "readdir","Cannot read block %d", i);
return -EIO;
}
ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
affs_brelse(fh_bh);
fh_bh = NULL;
}
if (ino)
goto inside;
hash_pos++;
for (; hash_pos < AFFS_SB(sb)->s_hashsize; hash_pos++) {
ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
if (!ino)
continue;
ctx->pos = (hash_pos << 16) + 2;
inside:
do {
fh_bh = affs_bread(sb, ino);
if (!fh_bh) {
affs_error(sb, "readdir","Cannot read block %d", ino);
break;
}
namelen = min(AFFS_TAIL(sb, fh_bh)->name[0], (u8)30);
name = AFFS_TAIL(sb, fh_bh)->name + 1;
pr_debug("AFFS: readdir(): filldir(\"%.*s\", ino=%u), hash=%d, f_pos=%x\n",
namelen, name, ino, hash_pos, (u32)ctx->pos);
if (!dir_emit(ctx, name, namelen, ino, DT_UNKNOWN))
goto readdir_done;
ctx->pos++;
ino = be32_to_cpu(AFFS_TAIL(sb, fh_bh)->hash_chain);
affs_brelse(fh_bh);
fh_bh = NULL;
} while (ino);
}
readdir_done:
file->f_version = inode->i_version;
file->private_data = (void *)(long)ino;
readdir_out:
affs_brelse(dir_bh);
affs_brelse(fh_bh);
affs_unlock_dir(inode);
return 0;
}