path: root/fs/f2fs/dir.c

// SPDX-License-Identifier: GPL-2.0
/*
 * fs/f2fs/dir.c
 *
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 *             http://www.samsung.com/
 */
#include <linux/unaligned.h>
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include <linux/sched/signal.h>
#include <linux/unicode.h>
#include "f2fs.h"
#include "node.h"
#include "acl.h"
#include "xattr.h"
#include <trace/events/f2fs.h>

#if IS_ENABLED(CONFIG_UNICODE)
extern struct kmem_cache *f2fs_cf_name_slab;
#endif

static unsigned long dir_blocks(struct inode *inode)
{
	return ((unsigned long long) (i_size_read(inode) + PAGE_SIZE - 1))
							>> PAGE_SHIFT;
}

static unsigned int dir_buckets(unsigned int level, int dir_level)
{
	if (level + dir_level < MAX_DIR_HASH_DEPTH / 2)
		return BIT(level + dir_level);
	else
		return MAX_DIR_BUCKETS;
}

static unsigned int bucket_blocks(unsigned int level)
{
	if (level < MAX_DIR_HASH_DEPTH / 2)
		return 2;
	else
		return 4;
}

#if IS_ENABLED(CONFIG_UNICODE)
/* If @dir is casefolded, initialize @fname->cf_name from @fname->usr_fname. */
int f2fs_init_casefolded_name(const struct inode *dir,
			      struct f2fs_filename *fname)
{
	struct super_block *sb = dir->i_sb;
	unsigned char *buf;
	int len;

	if (IS_CASEFOLDED(dir) &&
	    !is_dot_dotdot(fname->usr_fname->name, fname->usr_fname->len)) {
		buf = f2fs_kmem_cache_alloc(f2fs_cf_name_slab,
					    GFP_NOFS, false, F2FS_SB(sb));
		if (!buf)
			return -ENOMEM;

		len = utf8_casefold(sb->s_encoding, fname->usr_fname,
				    buf, F2FS_NAME_LEN);
		if (len <= 0) {
			kmem_cache_free(f2fs_cf_name_slab, buf);
			if (sb_has_strict_encoding(sb))
				return -EINVAL;
			/* fall back to treating name as opaque byte sequence */
			return 0;
		}
		fname->cf_name.name = buf;
		fname->cf_name.len = len;
	}

	return 0;
}

void f2fs_free_casefolded_name(struct f2fs_filename *fname)
{
	unsigned char *buf = (unsigned char *)fname->cf_name.name;

	if (buf) {
		kmem_cache_free(f2fs_cf_name_slab, buf);
		fname->cf_name.name = NULL;
	}
}
#endif /* CONFIG_UNICODE */

static int __f2fs_setup_filename(const struct inode *dir,
				 const struct fscrypt_name *crypt_name,
				 struct f2fs_filename *fname)
{
	int err;

	memset(fname, 0, sizeof(*fname));

	fname->usr_fname = crypt_name->usr_fname;
	fname->disk_name = crypt_name->disk_name;
#ifdef CONFIG_FS_ENCRYPTION
	fname->crypto_buf = crypt_name->crypto_buf;
#endif
	if (crypt_name->is_nokey_name) {
		/* hash was decoded from the no-key name */
		fname->hash = cpu_to_le32(crypt_name->hash);
	} else {
		err = f2fs_init_casefolded_name(dir, fname);
		if (err) {
			f2fs_free_filename(fname);
			return err;
		}
		f2fs_hash_filename(dir, fname);
	}
	return 0;
}

/*
 * Prepare to search for @iname in @dir.  This is similar to
 * fscrypt_setup_filename(), but this also handles computing the casefolded name
 * and the f2fs dirhash if needed, then packing all the information about this
 * filename up into a 'struct f2fs_filename'.
 */
int f2fs_setup_filename(struct inode *dir, const struct qstr *iname,
			int lookup, struct f2fs_filename *fname)
{
	struct fscrypt_name crypt_name;
	int err;

	err = fscrypt_setup_filename(dir, iname, lookup, &crypt_name);
	if (err)
		return err;

	return __f2fs_setup_filename(dir, &crypt_name, fname);
}

/*
 * Prepare to look up @dentry in @dir.  This is similar to
 * fscrypt_prepare_lookup(), but this also handles computing the casefolded name
 * and the f2fs dirhash if needed, then packing all the information about this
 * filename up into a 'struct f2fs_filename'.
 */
int f2fs_prepare_lookup(struct inode *dir, struct dentry *dentry,
			struct f2fs_filename *fname)
{
	struct fscrypt_name crypt_name;
	int err;

	err = fscrypt_prepare_lookup(dir, dentry, &crypt_name);
	if (err)
		return err;

	return __f2fs_setup_filename(dir, &crypt_name, fname);
}

void f2fs_free_filename(struct f2fs_filename *fname)
{
#ifdef CONFIG_FS_ENCRYPTION
	kfree(fname->crypto_buf.name);
	fname->crypto_buf.name = NULL;
#endif
	f2fs_free_casefolded_name(fname);
}

static unsigned long dir_block_index(unsigned int level,
				int dir_level, unsigned int idx)
{
	unsigned long i;
	unsigned long bidx = 0;

	for (i = 0; i < level; i++)
		bidx += mul_u32_u32(dir_buckets(i, dir_level),
				    bucket_blocks(i));