staging: exfat: add exfat filesystem code to staging

The exfat code needs a lot of work to get it into "real" shape for
the fs/ part of the kernel, so put it into drivers/staging/ for now so
that it can be worked on by everyone in the community.

The full specification of the filesystem can be found at:
  https://docs.microsoft.com/en-us/windows/win32/fileio/exfat-specificationSigned-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20190828160817.6250-1-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -6097,6 +6097,11 @@ F:	include/trace/events/mdio.h
 F:	include/uapi/linux/mdio.h
 F:	include/uapi/linux/mii.h
 
+EXFAT FILE SYSTEM
+M:	Valdis Kletnieks <valdis.kletnieks@vt.edu>
+S:	Maintained
+F:	fs/exfat/
+
 EXT2 FILE SYSTEM
 M:	Jan Kara <jack@suse.com>
 L:	linux-ext4@vger.kernel.org

drivers/staging/Kconfig

@@ -118,4 +118,6 @@ source "drivers/staging/kpc2000/Kconfig"
 
 source "drivers/staging/isdn/Kconfig"
 
+source "drivers/staging/exfat/Kconfig"
+
 endif # STAGING

drivers/staging/Makefile

@@ -49,3 +49,4 @@ obj-$(CONFIG_XIL_AXIS_FIFO)	+= axis-fifo/
 obj-$(CONFIG_FIELDBUS_DEV)     += fieldbus/
 obj-$(CONFIG_KPC2000)		+= kpc2000/
 obj-$(CONFIG_ISDN_CAPI)		+= isdn/
+obj-$(CONFIG_EXFAT_FS)		+= exfat/

drivers/staging/exfat/Kconfig

+config EXFAT_FS
+	tristate "exFAT fs support"
+	select NLS
+	help
+	  This adds support for the exFAT file system.
+
+config EXFAT_DISCARD
+	bool "enable discard support"
+	depends on EXFAT_FS
+	default y
+
+config EXFAT_DELAYED_SYNC
+	bool "enable delayed sync"
+	depends on EXFAT_FS
+	default n
+
+config EXFAT_KERNEL_DEBUG
+	bool "enable kernel debug features via ioctl"
+	depends on EXFAT_FS
+	default n
+
+config EXFAT_DEBUG_MSG
+	bool "print debug messages"
+	depends on EXFAT_FS
+	default n
+
+config EXFAT_DEFAULT_CODEPAGE
+	int "Default codepage for exFAT"
+	default 437
+	depends on EXFAT_FS
+	help
+	  This option should be set to the codepage of your exFAT filesystems.
+
+config EXFAT_DEFAULT_IOCHARSET
+	string "Default iocharset for exFAT"
+	default "utf8"
+	depends on EXFAT_FS
+	help
+	  Set this to the default input/output character set you'd like exFAT to use.

drivers/staging/exfat/Makefile

+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_EXFAT_FS) += exfat.o
+
+exfat-y :=	exfat_core.o	\
+		exfat_super.o	\
+		exfat_blkdev.o	\
+		exfat_cache.o	\
+		exfat_nls.o	\
+		exfat_upcase.o

drivers/staging/exfat/TODO

+exfat_core.c - ffsReadFile - the goto err_out seem to leak a brelse().
+same for ffsWriteFile.
+
+exfat_core.c - fs_sync(sb,0) all over the place looks fishy as hell.
+There's only one place that calls it with a non-zero argument.
+
+ffsTruncateFile -  if (old_size <= new_size) {
+That doesn't look right. How did it ever work? Are they relying on lazy
+block allocation when actual writes happen? If nothing else, it never
+does the 'fid->size = new_size' and do the inode update....
+
+ffsSetAttr() is just dangling in the breeze, not wired up at all...

drivers/staging/exfat/exfat_blkdev.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
+ */
+
+#include <linux/blkdev.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+#include "exfat.h"
+
+void bdev_open(struct super_block *sb)
+{
+	struct bd_info_t *p_bd = &(EXFAT_SB(sb)->bd_info);
+
+	if (p_bd->opened)
+		return;
+
+	p_bd->sector_size      = bdev_logical_block_size(sb->s_bdev);
+	p_bd->sector_size_bits = ilog2(p_bd->sector_size);
+	p_bd->sector_size_mask = p_bd->sector_size - 1;
+	p_bd->num_sectors      = i_size_read(sb->s_bdev->bd_inode) >>
+				 p_bd->sector_size_bits;
+	p_bd->opened = true;
+}
+
+void bdev_close(struct super_block *sb)
+{
+	struct bd_info_t *p_bd = &(EXFAT_SB(sb)->bd_info);
+
+	p_bd->opened = false;
+}
+
+int bdev_read(struct super_block *sb, sector_t secno, struct buffer_head **bh,
+	      u32 num_secs, bool read)
+{
+	struct bd_info_t *p_bd = &(EXFAT_SB(sb)->bd_info);
+	struct fs_info_t *p_fs = &(EXFAT_SB(sb)->fs_info);
+#ifdef CONFIG_EXFAT_KERNEL_DEBUG
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	long flags = sbi->debug_flags;
+
+	if (flags & EXFAT_DEBUGFLAGS_ERROR_RW)
+		return FFS_MEDIAERR;
+#endif /* CONFIG_EXFAT_KERNEL_DEBUG */
+
+	if (!p_bd->opened)
+		return FFS_MEDIAERR;
+
+	if (*bh)
+		__brelse(*bh);
+
+	if (read)
+		*bh = __bread(sb->s_bdev, secno,
+			      num_secs << p_bd->sector_size_bits);
+	else
+		*bh = __getblk(sb->s_bdev, secno,
+			       num_secs << p_bd->sector_size_bits);
+
+	if (*bh)
+		return 0;
+
+	WARN(!p_fs->dev_ejected,
+	     "[EXFAT] No bh, device seems wrong or to be ejected.\n");
+
+	return FFS_MEDIAERR;
+}
+
+int bdev_write(struct super_block *sb, sector_t secno, struct buffer_head *bh,
+	       u32 num_secs, bool sync)
+{
+	s32 count;
+	struct buffer_head *bh2;
+	struct bd_info_t *p_bd = &(EXFAT_SB(sb)->bd_info);
+	struct fs_info_t *p_fs = &(EXFAT_SB(sb)->fs_info);
+#ifdef CONFIG_EXFAT_KERNEL_DEBUG
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	long flags = sbi->debug_flags;
+
+	if (flags & EXFAT_DEBUGFLAGS_ERROR_RW)
+		return FFS_MEDIAERR;
+#endif /* CONFIG_EXFAT_KERNEL_DEBUG */
+
+	if (!p_bd->opened)
+		return FFS_MEDIAERR;
+
+	if (secno == bh->b_blocknr) {
+		lock_buffer(bh);
+		set_buffer_uptodate(bh);
+		mark_buffer_dirty(bh);
+		unlock_buffer(bh);
+		if (sync && (sync_dirty_buffer(bh) != 0))
+			return FFS_MEDIAERR;
+	} else {
+		count = num_secs << p_bd->sector_size_bits;
+
+		bh2 = __getblk(sb->s_bdev, secno, count);
+		if (!bh2)
+			goto no_bh;
+
+		lock_buffer(bh2);
+		memcpy(bh2->b_data, bh->b_data, count);
+		set_buffer_uptodate(bh2);
+		mark_buffer_dirty(bh2);
+		unlock_buffer(bh2);
+		if (sync && (sync_dirty_buffer(bh2) != 0)) {
+			__brelse(bh2);
+			goto no_bh;
+		}
+		__brelse(bh2);
+	}
+
+	return 0;
+
+no_bh:
+	WARN(!p_fs->dev_ejected,
+	     "[EXFAT] No bh, device seems wrong or to be ejected.\n");
+
+	return FFS_MEDIAERR;
+}
+
+int bdev_sync(struct super_block *sb)
+{
+	struct bd_info_t *p_bd = &(EXFAT_SB(sb)->bd_info);
+#ifdef CONFIG_EXFAT_KERNEL_DEBUG
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	long flags = sbi->debug_flags;
+
+	if (flags & EXFAT_DEBUGFLAGS_ERROR_RW)
+		return FFS_MEDIAERR;
+#endif /* CONFIG_EXFAT_KERNEL_DEBUG */
+
+	if (!p_bd->opened)
+		return FFS_MEDIAERR;
+
+	return sync_blockdev(sb->s_bdev);
+}

drivers/staging/exfat/exfat_nls.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
+ */
+
+#include <linux/string.h>
+#include <linux/nls.h>
+#include "exfat.h"
+
+static u16 bad_dos_chars[] = {
+	/* + , ; = [ ] */
+	0x002B, 0x002C, 0x003B, 0x003D, 0x005B, 0x005D,
+	0xFF0B, 0xFF0C, 0xFF1B, 0xFF1D, 0xFF3B, 0xFF3D,
+	0
+};
+
+static u16 bad_uni_chars[] = {
+	/* " * / : < > ? \ | */
+	0x0022,         0x002A, 0x002F, 0x003A,
+	0x003C, 0x003E, 0x003F, 0x005C, 0x007C,
+	0
+};
+
+static int convert_ch_to_uni(struct nls_table *nls, u16 *uni, u8 *ch,
+			     bool *lossy)
+{
+	int len;
+
+	*uni = 0x0;
+
+	if (ch[0] < 0x80) {
+		*uni = (u16)ch[0];
+		return 1;
+	}
+
+	len = nls->char2uni(ch, NLS_MAX_CHARSET_SIZE, uni);
+	if (len < 0) {
+		/* conversion failed */
+		pr_info("%s: fail to use nls\n", __func__);
+		if (lossy)
+			*lossy = true;
+		*uni = (u16)'_';
+		if (!strcmp(nls->charset, "utf8"))
+			return 1;
+		else
+			return 2;
+	}
+
+	return len;
+}
+
+static int convert_uni_to_ch(struct nls_table *nls, u8 *ch, u16 uni,
+			     bool *lossy)
+{
+	int len;
+
+	ch[0] = 0x0;
+
+	if (uni < 0x0080) {
+		ch[0] = (u8)uni;
+		return 1;
+	}
+
+	len = nls->uni2char(uni, ch, NLS_MAX_CHARSET_SIZE);
+	if (len < 0) {
+		/* conversion failed */
+		pr_info("%s: fail to use nls\n", __func__);
+		if (lossy)
+			*lossy = true;
+		ch[0] = '_';
+		return 1;
+	}
+
+	return len;
+}
+
+u16 nls_upper(struct super_block *sb, u16 a)
+{
+	struct fs_info_t *p_fs = &(EXFAT_SB(sb)->fs_info);
+
+	if (EXFAT_SB(sb)->options.casesensitive)
+		return a;
+	if (p_fs->vol_utbl && p_fs->vol_utbl[get_col_index(a)])
+		return p_fs->vol_utbl[get_col_index(a)][get_row_index(a)];
+	else
+		return a;
+}
+
+static u16 *nls_wstrchr(u16 *str, u16 wchar)
+{
+	while (*str) {
+		if (*(str++) == wchar)
+			return str;
+	}
+
+	return NULL;
+}
+
+int nls_dosname_cmp(struct super_block *sb, u8 *a, u8 *b)
+{
+	return strncmp(a, b, DOS_NAME_LENGTH);
+}
+
+int nls_uniname_cmp(struct super_block *sb, u16 *a, u16 *b)
+{
+	int i;
+
+	for (i = 0; i < MAX_NAME_LENGTH; i++, a++, b++) {
+		if (nls_upper(sb, *a) != nls_upper(sb, *b))
+			return 1;
+		if (*a == 0x0)
+			return 0;
+	}
+	return 0;
+}
+
+void nls_uniname_to_dosname(struct super_block *sb,
+			    struct dos_name_t *p_dosname,
+			    struct uni_name_t *p_uniname, bool *p_lossy)
+{
+	int i, j, len;
+	bool lossy = false;
+	u8 buf[MAX_CHARSET_SIZE];
+	u8 lower = 0, upper = 0;
+	u8 *dosname = p_dosname->name;
+	u16 *uniname = p_uniname->name;
+	u16 *p, *last_period;
+	struct nls_table *nls = EXFAT_SB(sb)->nls_disk;
+
+	for (i = 0; i < DOS_NAME_LENGTH; i++)
+		*(dosname + i) = ' ';
+
+	if (!nls_uniname_cmp(sb, uniname, (u16 *)UNI_CUR_DIR_NAME)) {
+		*(dosname) = '.';
+		p_dosname->name_case = 0x0;
+		if (p_lossy)
+			*p_lossy = false;
+		return;
+	}
+
+	if (!nls_uniname_cmp(sb, uniname, (u16 *)UNI_PAR_DIR_NAME)) {
+		*(dosname) = '.';
+		*(dosname + 1) = '.';
+		p_dosname->name_case = 0x0;
+		if (p_lossy)
+			*p_lossy = false;
+		return;
+	}
+
+	/* search for the last embedded period */
+	last_period = NULL;
+	for (p = uniname; *p; p++) {
+		if (*p == (u16)'.')
+			last_period = p;
+	}
+
+	i = 0;
+	while (i < DOS_NAME_LENGTH) {
+		if (i == 8) {
+			if (!last_period)
+				break;
+
+			if (uniname <= last_period) {
+				if (uniname < last_period)
+					lossy = true;
+				uniname = last_period + 1;
+			}
+		}
+
+		if (*uniname == (u16)'\0') {
+			break;
+		} else if (*uniname == (u16)' ') {
+			lossy = true;
+		} else if (*uniname == (u16)'.') {
+			if (uniname < last_period)
+				lossy = true;
+			else
+				i = 8;
+		} else if (nls_wstrchr(bad_dos_chars, *uniname)) {
+			lossy = true;
+			*(dosname + i) = '_';
+			i++;
+		} else {
+			len = convert_uni_to_ch(nls, buf, *uniname, &lossy);
+
+			if (len > 1) {
+				if ((i >= 8) && ((i + len) > DOS_NAME_LENGTH))
+					break;
+
+				if ((i < 8) && ((i + len) > 8)) {
+					i = 8;
+					continue;
+				}
+
+				lower = 0xFF;
+
+				for (j = 0; j < len; j++, i++)
+					*(dosname + i) = *(buf + j);
+			} else { /* len == 1 */
+				if ((*buf >= 'a') && (*buf <= 'z')) {
+					*(dosname + i) = *buf - ('a' - 'A');
+
+					if (i < 8)
+						lower |= 0x08;
+					else
+						lower |= 0x10;
+				} else if ((*buf >= 'A') && (*buf <= 'Z')) {
+					*(dosname + i) = *buf;
+
+					if (i < 8)
+						upper |= 0x08;
+					else
+						upper |= 0x10;
+				} else {
+					*(dosname + i) = *buf;
+				}
+				i++;
+			}
+		}
+
+		uniname++;
+	}
+
+	if (*dosname == 0xE5)
+		*dosname = 0x05;
+
+	if (*uniname != 0x0)
+		lossy = TRUE;
+
+	if (upper & lower)
+		p_dosname->name_case = 0xFF;
+	else
+		p_dosname->name_case = lower;
+
+	if (p_lossy)
+		*p_lossy = lossy;
+}
+
+void nls_dosname_to_uniname(struct super_block *sb,
+			    struct uni_name_t *p_uniname,
+			    struct dos_name_t *p_dosname)
+{
+	int i = 0, j, n = 0;
+	u8 buf[DOS_NAME_LENGTH + 2];
+	u8 *dosname = p_dosname->name;
+	u16 *uniname = p_uniname->name;
+	struct nls_table *nls = EXFAT_SB(sb)->nls_disk;
+
+	if (*dosname == 0x05) {
+		*buf = 0xE5;
+		i++;
+		n++;
+	}
+
+	for (; i < 8; i++, n++) {
+		if (*(dosname + i) == ' ')
+			break;
+
+		if ((*(dosname + i) >= 'A') && (*(dosname + i) <= 'Z') &&
+		    (p_dosname->name_case & 0x08))
+			*(buf + n) = *(dosname + i) + ('a' - 'A');
+		else
+			*(buf + n) = *(dosname + i);
+	}
+	if (*(dosname + 8) != ' ') {
+		*(buf + n) = '.';
+		n++;
+	}
+
+	for (i = 8; i < DOS_NAME_LENGTH; i++, n++) {
+		if (*(dosname + i) == ' ')
+			break;
+
+		if ((*(dosname + i) >= 'A') && (*(dosname + i) <= 'Z') &&
+		    (p_dosname->name_case & 0x10))
+			*(buf + n) = *(dosname + i) + ('a' - 'A');
+		else
+			*(buf + n) = *(dosname + i);
+	}
+	*(buf + n) = '\0';
+
+	i = 0;
+	j = 0;
+	while (j < (MAX_NAME_LENGTH - 1)) {
+		if (*(buf + i) == '\0')
+			break;
+
+		i += convert_ch_to_uni(nls, uniname, (buf + i), NULL);
+
+		uniname++;
+		j++;
+	}
+
+	*uniname = (u16)'\0';
+}
+
+void nls_uniname_to_cstring(struct super_block *sb, u8 *p_cstring,
+			    struct uni_name_t *p_uniname)
+{
+	int i, j, len;
+	u8 buf[MAX_CHARSET_SIZE];
+	u16 *uniname = p_uniname->name;
+	struct nls_table *nls = EXFAT_SB(sb)->nls_io;
+
+	if (!nls) {
+		len = utf16s_to_utf8s(uniname, MAX_NAME_LENGTH,
+				      UTF16_HOST_ENDIAN, p_cstring,
+				      MAX_NAME_LENGTH);
+		p_cstring[len] = 0;
+		return;
+	}
+
+	i = 0;
+	while (i < (MAX_NAME_LENGTH - 1)) {
+		if (*uniname == (u16)'\0')
+			break;
+
+		len = convert_uni_to_ch(nls, buf, *uniname, NULL);
+
+		if (len > 1) {
+			for (j = 0; j < len; j++)
+				*p_cstring++ = (char)*(buf + j);
+		} else { /* len == 1 */
+			*p_cstring++ = (char)*buf;
+		}
+
+		uniname++;
+		i++;
+	}
+
+	*p_cstring = '\0';
+}
+
+void nls_cstring_to_uniname(struct super_block *sb,
+			    struct uni_name_t *p_uniname, u8 *p_cstring,
+			    bool *p_lossy)
+{
+	int i, j;
+	bool lossy = false;
+	u8 *end_of_name;
+	u8 upname[MAX_NAME_LENGTH * 2];
+	u16 *uniname = p_uniname->name;
+	struct nls_table *nls = EXFAT_SB(sb)->nls_io;
+
+	/* strip all trailing spaces */
+	end_of_name = p_cstring + strlen(p_cstring);
+
+	while (*(--end_of_name) == ' ') {
+		if (end_of_name < p_cstring)
+			break;
+	}
+	*(++end_of_name) = '\0';
+
+	if (strcmp(p_cstring, ".") && strcmp(p_cstring, "..")) {
+		/* strip all trailing periods */
+		while (*(--end_of_name) == '.') {
+			if (end_of_name < p_cstring)
+				break;
+		}
+		*(++end_of_name) = '\0';
+	}
+
+	if (*p_cstring == '\0')
+		lossy = true;
+
+	if (!nls) {
+		i = utf8s_to_utf16s(p_cstring, MAX_NAME_LENGTH,
+				    UTF16_HOST_ENDIAN, uniname,
+				    MAX_NAME_LENGTH);
+		for (j = 0; j < i; j++)
+			SET16_A(upname + j * 2, nls_upper(sb, uniname[j]));
+		uniname[i] = '\0';
+	} else {
+		i = 0;
+		j = 0;
+		while (j < (MAX_NAME_LENGTH - 1)) {
+			if (*(p_cstring + i) == '\0')
+				break;
+
+			i += convert_ch_to_uni(nls, uniname,
+					       (u8 *)(p_cstring + i), &lossy);
+
+			if ((*uniname < 0x0020) ||
+			    nls_wstrchr(bad_uni_chars, *uniname))
+				lossy = true;
+
+			SET16_A(upname + j * 2, nls_upper(sb, *uniname));
+
+			uniname++;
+			j++;
+		}
+
+		if (*(p_cstring + i) != '\0')
+			lossy = true;
+		*uniname = (u16)'\0';
+	}
+
+	p_uniname->name_len = j;
+	p_uniname->name_hash = calc_checksum_2byte(upname, j << 1, 0,
+						   CS_DEFAULT);
+
+	if (p_lossy)
+		*p_lossy = lossy;
+}