path: root/fs/ntfs3/super.c

// SPDX-License-Identifier: GPL-2.0
/*
 *
 * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
 *
 *
 *                 terminology
 *
 * cluster - allocation unit     - 512,1K,2K,4K,...,2M
 * vcn - virtual cluster number  - Offset inside the file in clusters.
 * vbo - virtual byte offset     - Offset inside the file in bytes.
 * lcn - logical cluster number  - 0 based cluster in clusters heap.
 * lbo - logical byte offset     - Absolute position inside volume.
 * run - maps VCN to LCN         - Stored in attributes in packed form.
 * attr - attribute segment      - std/name/data etc records inside MFT.
 * mi  - MFT inode               - One MFT record(usually 1024 bytes or 4K), consists of attributes.
 * ni  - NTFS inode              - Extends linux inode. consists of one or more mft inodes.
 * index - unit inside directory - 2K, 4K, <=page size, does not depend on cluster size.
 *
 * WSL - Windows Subsystem for Linux
 * https://docs.microsoft.com/en-us/windows/wsl/file-permissions
 * It stores uid/gid/mode/dev in xattr
 *
 * ntfs allows up to 2^64 clusters per volume.
 * It means you should use 64 bits lcn to operate with ntfs.
 * Implementation of ntfs.sys uses only 32 bits lcn.
 * Default ntfs3 uses 32 bits lcn too.
 * ntfs3 built with CONFIG_NTFS3_64BIT_CLUSTER (ntfs3_64) uses 64 bits per lcn.
 *
 *
 *     ntfs limits, cluster size is 4K (2^12)
 * -----------------------------------------------------------------------------
 * | Volume size   | Clusters | ntfs.sys | ntfs3  | ntfs3_64 | mkntfs | chkdsk |
 * -----------------------------------------------------------------------------
 * | < 16T, 2^44   |  < 2^32  |  yes     |  yes   |   yes    |  yes   |  yes   |
 * | > 16T, 2^44   |  > 2^32  |  no      |  no    |   yes    |  yes   |  yes   |
 * ----------------------------------------------------------|------------------
 *
 * To mount large volumes as ntfs one should use large cluster size (up to 2M)
 * The maximum volume size in this case is 2^32 * 2^21 = 2^53 = 8P
 *
 *     ntfs limits, cluster size is 2M (2^21)
 * -----------------------------------------------------------------------------
 * | < 8P, 2^53    |  < 2^32  |  yes     |  yes   |   yes    |  yes   |  yes   |
 * | > 8P, 2^53    |  > 2^32  |  no      |  no    |   yes    |  yes   |  yes   |
 * ----------------------------------------------------------|------------------
 *
 */

#include <linux/blkdev.h>
#include <linux/buffer_head.h>
#include <linux/exportfs.h>
#include <linux/fs.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/log2.h>
#include <linux/minmax.h>
#include <linux/module.h>
#include <linux/nls.h>
#include <linux/seq_file.h>
#include <linux/statfs.h>

#include "debug.h"
#include "ntfs.h"
#include "ntfs_fs.h"
#ifdef CONFIG_NTFS3_LZX_XPRESS
#include "lib/lib.h"
#endif

#ifdef CONFIG_PRINTK
/*
 * ntfs_printk - Trace warnings/notices/errors.
 *
 * Thanks Joe Perches <joe@perches.com> for implementation
 */
void ntfs_printk(const struct super_block *sb, const char *fmt, ...)
{
	struct va_format vaf;
	va_list args;
	int level;
	struct ntfs_sb_info *sbi = sb->s_fs_info;

	/* Should we use different ratelimits for warnings/notices/errors? */
	if (!___ratelimit(&sbi->msg_ratelimit, "ntfs3"))
		return;

	va_start(args, fmt);

	level = printk_get_level(fmt);
	vaf.fmt = printk_skip_level(fmt);
	vaf.va = &args;
	printk("%c%cntfs3: %s: %pV\n", KERN_SOH_ASCII, level, sb->s_id, &vaf);

	va_end(args);
}

static char s_name_buf[512];
static atomic_t s_name_buf_cnt = ATOMIC_INIT(1); // 1 means 'free s_name_buf'.

/*
 * ntfs_inode_printk
 *
 * Print warnings/notices/errors about inode using name or inode number.
 */
void ntfs_inode_printk(struct inode *inode, const char *fmt, ...)
{
	struct super_block *sb = inode->i_sb;
	struct ntfs_sb_info *sbi = sb->s_fs_info;
	char *name;
	va_list args;
	struct va_format vaf;
	int level;

	if (!___ratelimit(&sbi->msg_ratelimit, "ntfs3"))
		return;

	/* Use static allocated buffer, if possible. */
	name = atomic_dec_and_test(&s_name_buf_cnt) ?
			     s_name_buf :
			     kmalloc(sizeof(s_name_buf), GFP_NOFS);

	if (name) {
		struct dentry *de = d_find_alias(inode);
		const u32 name_len = ARRAY_SIZE(s_name_buf) - 1;

		if (de) {
			spin_lock(&de->d_lock);
			snprintf(name, name_len, " \"%s\"", de->d_name.name);
			spin_unlock(&de->d_lock);
			name[name_len] = 0; /* To be sure. */
		} else {
			name[0] = 0;
		}
		dput(de); /* Cocci warns if placed in branch