linux/fs/ext4/dir.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/ext4/dir.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card ([email protected])
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/dir.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  ext4 directory handling functions
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller ([email protected]), 1995
 *
 * Hash Tree Directory indexing (c) 2001  Daniel Phillips
 *
 */

#include <linux/fs.h>
#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <linux/iversion.h>
#include <linux/unicode.h>
#include "ext4.h"
#include "xattr.h"

static int ext4_dx_readdir(struct file *, struct dir_context *);

/**
 * is_dx_dir() - check if a directory is using htree indexing
 * @inode: directory inode
 *
 * Check if the given dir-inode refers to an htree-indexed directory
 * (or a directory which could potentially get converted to use htree
 * indexing).
 *
 * Return 1 if it is a dx dir, 0 if not
 */
static int is_dx_dir(struct inode *inode)
{ … }

static bool is_fake_dir_entry(struct ext4_dir_entry_2 *de)
{ … }

/*
 * Return 0 if the directory entry is OK, and 1 if there is a problem
 *
 * Note: this is the opposite of what ext2 and ext3 historically returned...
 *
 * bh passed here can be an inode block or a dir data block, depending
 * on the inode inline data flag.
 */
int __ext4_check_dir_entry(const char *function, unsigned int line,
			   struct inode *dir, struct file *filp,
			   struct ext4_dir_entry_2 *de,
			   struct buffer_head *bh, char *buf, int size,
			   unsigned int offset)
{ … }

static int ext4_readdir(struct file *file, struct dir_context *ctx)
{ … }

static inline int is_32bit_api(void)
{ … }

/*
 * These functions convert from the major/minor hash to an f_pos
 * value for dx directories
 *
 * Upper layer (for example NFS) should specify FMODE_32BITHASH or
 * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
 * directly on both 32-bit and 64-bit nodes, under such case, neither
 * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
 */
static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
{ … }

static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
{ … }

static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
{ … }

/*
 * Return 32- or 64-bit end-of-file for dx directories
 */
static inline loff_t ext4_get_htree_eof(struct file *filp)
{ … }


/*
 * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
 * directories, where the "offset" is in terms of the filename hash
 * value instead of the byte offset.
 *
 * Because we may return a 64-bit hash that is well beyond offset limits,
 * we need to pass the max hash as the maximum allowable offset in
 * the htree directory case.
 *
 * For non-htree, ext4_llseek already chooses the proper max offset.
 */
static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
{ … }

/*
 * This structure holds the nodes of the red-black tree used to store
 * the directory entry in hash order.
 */
struct fname { … };

/*
 * This function implements a non-recursive way of freeing all of the
 * nodes in the red-black tree.
 */
static void free_rb_tree_fname(struct rb_root *root)
{ … }


static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
							   loff_t pos)
{ … }

void ext4_htree_free_dir_info(struct dir_private_info *p)
{ … }

/*
 * Given a directory entry, enter it into the fname rb tree.
 *
 * When filename encryption is enabled, the dirent will hold the
 * encrypted filename, while the htree will hold decrypted filename.
 * The decrypted filename is passed in via ent_name.  parameter.
 */
int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
			     __u32 minor_hash,
			    struct ext4_dir_entry_2 *dirent,
			    struct fscrypt_str *ent_name)
{ … }



/*
 * This is a helper function for ext4_dx_readdir.  It calls filldir
 * for all entries on the fname linked list.  (Normally there is only
 * one entry on the linked list, unless there are 62 bit hash collisions.)
 */
static int call_filldir(struct file *file, struct dir_context *ctx,
			struct fname *fname)
{ … }

static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
{ … }

static int ext4_release_dir(struct inode *inode, struct file *filp)
{ … }

int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
		      int buf_size)
{ … }

const struct file_operations ext4_dir_operations = …;