linux/fs/ext2/dir.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/ext2/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
 *
 *  ext2 directory handling functions
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller ([email protected]), 1995
 *
 * All code that works with directory layout had been switched to pagecache
 * and moved here. AV
 */

#include "ext2.h"
#include <linux/buffer_head.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/iversion.h>

ext2_dirent;

/*
 * Tests against MAX_REC_LEN etc were put in place for 64k block
 * sizes; if that is not possible on this arch, we can skip
 * those tests and speed things up.
 */
static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
{ … }

static inline __le16 ext2_rec_len_to_disk(unsigned len)
{ … }

/*
 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
 * more robust, but we have what we have
 */
static inline unsigned ext2_chunk_size(struct inode *inode)
{ … }

/*
 * Return the offset into page `page_nr' of the last valid
 * byte in that page, plus one.
 */
static unsigned
ext2_last_byte(struct inode *inode, unsigned long page_nr)
{ … }

static void ext2_commit_chunk(struct folio *folio, loff_t pos, unsigned len)
{ … }

static bool ext2_check_folio(struct folio *folio, int quiet, char *kaddr)
{ … }

/*
 * Calls to ext2_get_folio()/folio_release_kmap() must be nested according
 * to the rules documented in kmap_local_folio()/kunmap_local().
 *
 * NOTE: ext2_find_entry() and ext2_dotdot() act as a call
 * to folio_release_kmap() and should be treated as a call to
 * folio_release_kmap() for nesting purposes.
 */
static void *ext2_get_folio(struct inode *dir, unsigned long n,
				   int quiet, struct folio **foliop)
{ … }

/*
 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
 *
 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
 */
static inline int ext2_match (int len, const char * const name,
					struct ext2_dir_entry_2 * de)
{ … }

/*
 * p is at least 6 bytes before the end of page
 */
static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
{ … }

static inline unsigned 
ext2_validate_entry(char *base, unsigned offset, unsigned mask)
{ … }

static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
{ … }

static int
ext2_readdir(struct file *file, struct dir_context *ctx)
{ … }

/*
 *	ext2_find_entry()
 *
 * finds an entry in the specified directory with the wanted name. It
 * returns the page in which the entry was found (as a parameter - res_page),
 * and the entry itself. Page is returned mapped and unlocked.
 * Entry is guaranteed to be valid.
 *
 * On Success folio_release_kmap() should be called on *foliop.
 *
 * NOTE: Calls to ext2_get_folio()/folio_release_kmap() must be nested
 * according to the rules documented in kmap_local_folio()/kunmap_local().
 *
 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_folio()
 * and should be treated as a call to ext2_get_folio() for nesting
 * purposes.
 */
struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
			const struct qstr *child, struct folio **foliop)
{ … }

/*
 * Return the '..' directory entry and the page in which the entry was found
 * (as a parameter - p).
 *
 * On Success folio_release_kmap() should be called on *foliop.
 *
 * NOTE: Calls to ext2_get_folio()/folio_release_kmap() must be nested
 * according to the rules documented in kmap_local_folio()/kunmap_local().
 *
 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_folio()
 * and should be treated as a call to ext2_get_folio() for nesting
 * purposes.
 */
struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct folio **foliop)
{ … }

int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino)
{ … }

static int ext2_prepare_chunk(struct folio *folio, loff_t pos, unsigned len)
{ … }

static int ext2_handle_dirsync(struct inode *dir)
{ … }

int ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
		struct folio *folio, struct inode *inode, bool update_times)
{ … }

/*
 *	Parent is locked.
 */
int ext2_add_link (struct dentry *dentry, struct inode *inode)
{ … }

/*
 * ext2_delete_entry deletes a directory entry by merging it with the
 * previous entry. Page is up-to-date.
 */
int ext2_delete_entry(struct ext2_dir_entry_2 *dir, struct folio *folio)
{ … }

/*
 * Set the first fragment of directory.
 */
int ext2_make_empty(struct inode *inode, struct inode *parent)
{ … }

/*
 * routine to check that the specified directory is empty (for rmdir)
 */
int ext2_empty_dir(struct inode *inode)
{ … }

const struct file_operations ext2_dir_operations = …;