[GitHub/LineageOS/android_kernel_samsung_universal7580.git] / fs / sdfat / fatent.c

/*
 *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

/************************************************************************/
/*                                                                      */
/*  PROJECT : exFAT & FAT12/16/32 File System                           */
/*  FILE    : fatent.c                                                  */
/*  PURPOSE : sdFAT FAT entry manager                                   */
/*                                                                      */
/*----------------------------------------------------------------------*/
/*  NOTES                                                               */
/*                                                                      */
/*                                                                      */
/************************************************************************/

#include <asm/unaligned.h>

#include "sdfat.h"
#include "core.h"

/*----------------------------------------------------------------------*/
/*  Global Variable Definitions                                         */
/*----------------------------------------------------------------------*/
/* All buffer structures are protected w/ fsi->v_sem */

/*----------------------------------------------------------------------*/
/*  Static functions                                                    */
/*----------------------------------------------------------------------*/

/*======================================================================*/
/*  FAT Read/Write Functions                                            */
/*======================================================================*/
/* in : sb, loc
 * out: content
 * returns 0 on success, -1 on error
 */
static s32 exfat_ent_get(struct super_block *sb, u32 loc, u32 *content)
{
	u32 off, _content;
	u64 sec;
	u8 *fat_sector;
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	/* fsi->vol_type == EXFAT */
	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-2));
	off = (loc << 2) & (u32)(sb->s_blocksize - 1);

	fat_sector = fcache_getblk(sb, sec);
	if (!fat_sector)
		return -EIO;

	_content = le32_to_cpu(*(__le32 *)(&fat_sector[off]));

	/* remap reserved clusters to simplify code */
	if (_content >= CLUSTER_32(0xFFFFFFF8))
		_content = CLUS_EOF;

	*content = CLUSTER_32(_content);
	return 0;
}

static s32 exfat_ent_set(struct super_block *sb, u32 loc, u32 content)
{
	u32 off;
	u64 sec;
	u8 *fat_sector;
	__le32 *fat_entry;
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-2));
	off = (loc << 2) & (u32)(sb->s_blocksize - 1);

	fat_sector = fcache_getblk(sb, sec);
	if (!fat_sector)
		return -EIO;

	fat_entry = (__le32 *)&(fat_sector[off]);
	*fat_entry = cpu_to_le32(content);

	return fcache_modify(sb, sec);
}

#define FATENT_FAT32_VALID_MASK		(0x0FFFFFFFU)
#define FATENT_FAT32_IGNORE_MASK	(0xF0000000U)
static s32 fat32_ent_get(struct super_block *sb, u32 loc, u32 *content)
{
	u32 off, _content;
	u64 sec;
	u8 *fat_sector;
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-2));
	off = (loc << 2) & (u32)(sb->s_blocksize - 1);

	fat_sector = fcache_getblk(sb, sec);
	if (!fat_sector)
		return -EIO;

	_content = le32_to_cpu(*(__le32 *)(&fat_sector[off]));
	_content &= FATENT_FAT32_VALID_MASK;

	/* remap reserved clusters to simplify code */
	if (_content == CLUSTER_32(0x0FFFFFF7U))
		_content = CLUS_BAD;
	else if (_content >= CLUSTER_32(0x0FFFFFF8U))
		_content = CLUS_EOF;

	*content = CLUSTER_32(_content);
	return 0;
}

static s32 fat32_ent_set(struct super_block *sb, u32 loc, u32 content)
{
	u32 off;
	u64 sec;
	u8 *fat_sector;
	__le32 *fat_entry;
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	content &= FATENT_FAT32_VALID_MASK;

	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-2));
	off = (loc << 2) & (u32)(sb->s_blocksize - 1);

	fat_sector = fcache_getblk(sb, sec);
	if (!fat_sector)
		return -EIO;

	fat_entry = (__le32 *)&(fat_sector[off]);
	content |= (le32_to_cpu(*fat_entry) & FATENT_FAT32_IGNORE_MASK);
	*fat_entry = cpu_to_le32(content);

	return fcache_modify(sb, sec);
}

#define FATENT_FAT16_VALID_MASK		(0x0000FFFFU)
static s32 fat16_ent_get(struct super_block *sb, u32 loc, u32 *content)
{
	u32 off, _content;
	u64 sec;
	u8 *fat_sector;
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-1));
	off = (loc << 1) & (u32)(sb->s_blocksize - 1);

	fat_sector = fcache_getblk(sb, sec);
	if (!fat_sector)
		return -EIO;

	_content = (u32)le16_to_cpu(*(__le16 *)(&fat_sector[off]));
	_content &= FATENT_FAT16_VALID_MASK;

	/* remap reserved clusters to simplify code */
	if (_content == CLUSTER_16(0xFFF7U))
		_content = CLUS_BAD;
	else if (_content >= CLUSTER_16(0xFFF8U))
		_content = CLUS_EOF;

	*content = CLUSTER_32(_content);
	return 0;
}

static s32 fat16_ent_set(struct super_block *sb, u32 loc, u32 content)
{
	u32 off;
	u64 sec;
	u8 *fat_sector;
	__le16 *fat_entry;
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	content &= FATENT_FAT16_VALID_MASK;

	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-1));
	off = (loc << 1) & (u32)(sb->s_blocksize - 1);

	fat_sector = fcache_getblk(sb, sec);
	if (!fat_sector)
		return -EIO;

	fat_entry = (__le16 *)&(fat_sector[off]);
	*fat_entry = cpu_to_le16(content);

	return fcache_modify(sb, sec);
}

#define FATENT_FAT12_VALID_MASK		(0x00000FFFU)
static s32 fat12_ent_get(struct super_block *sb, u32 loc, u32 *content)
{
	u32 off, _content;
	u64 sec;
	u8 *fat_sector;
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	sec = fsi->FAT1_start_sector + ((loc + (loc >> 1)) >> sb->s_blocksize_bits);
	off = (loc + (loc >> 1)) & (u32)(sb->s_blocksize - 1);

	fat_sector = fcache_getblk(sb, sec);
	if (!fat_sector)
		return -EIO;

	if (off == (u32)(sb->s_blocksize - 1)) {
		_content  = (u32) fat_sector[off];

		fat_sector = fcache_getblk(sb, ++sec);
		if (!fat_sector)
			return -EIO;

		_content |= (u32) fat_sector[0] << 8;
	} else {
		_content = get_unaligned_le16(&fat_sector[off]);
	}

	if (loc & 1)
		_content >>= 4;

	_content &= FATENT_FAT12_VALID_MASK;

	/* remap reserved clusters to simplify code */
	if (_content == CLUSTER_16(0x0FF7U))
		_content = CLUS_BAD;
	else if (_content >= CLUSTER_16(0x0FF8U))
		_content = CLUS_EOF;

	*content = CLUSTER_32(_content);
	return 0;
}

static s32 fat12_ent_set(struct super_block *sb, u32 loc, u32 content)
{
	u32 off;
	u64 sec;
	u8 *fat_sector, *fat_entry;
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	content &= FATENT_FAT12_VALID_MASK;

	sec = fsi->FAT1_start_sector + ((loc + (loc >> 1)) >> sb->s_blocksize_bits);
	off = (loc + (loc >> 1)) & (u32)(sb->s_blocksize - 1);

	fat_sector = fcache_getblk(sb, sec);
	if (!fat_sector)
		return -EIO;

	if (loc & 1) { /* odd */

		content <<= 4;

		if (off == (u32)(sb->s_blocksize-1)) {
			fat_sector[off] = (u8)(content | (fat_sector[off] & 0x0F));
			if (fcache_modify(sb, sec))
				return -EIO;

			fat_sector = fcache_getblk(sb, ++sec);
			if (!fat_sector)
				return -EIO;

			fat_sector[0] = (u8)(content >> 8);
		} else {
			fat_entry = &(fat_sector[off]);
			content |= 0x000F & get_unaligned_le16(fat_entry);
			put_unaligned_le16(content, fat_entry);
		}
	} else { /* even */
		fat_sector[off] = (u8)(content);

		if (off == (u32)(sb->s_blocksize-1)) {
			fat_sector[off] = (u8)(content);
			if (fcache_modify(sb, sec))
				return -EIO;

			fat_sector = fcache_getblk(sb, ++sec);
			if (!fat_sector)
				return -EIO;

			fat_sector[0] = (u8)((fat_sector[0] & 0xF0) | (content >> 8));
		} else {
			fat_entry = &(fat_sector[off]);
			content |= 0xF000 & get_unaligned_le16(fat_entry);
			put_unaligned_le16(content, fat_entry);
		}
	}
	return fcache_modify(sb, sec);
}


static FATENT_OPS_T fat12_ent_ops = {
	fat12_ent_get,
	fat12_ent_set
};

static FATENT_OPS_T fat16_ent_ops = {
	fat16_ent_get,
	fat16_ent_set
};

static FATENT_OPS_T fat32_ent_ops = {
	fat32_ent_get,
	fat32_ent_set
};

static FATENT_OPS_T exfat_ent_ops = {
	exfat_ent_get,
	exfat_ent_set
};

s32 fat_ent_ops_init(struct super_block *sb)
{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	switch (fsi->vol_type) {
	case EXFAT:
		fsi->fatent_ops = &exfat_ent_ops;
		break;
	case FAT32:
		fsi->fatent_ops = &fat32_ent_ops;
		break;
	case FAT16:
		fsi->fatent_ops = &fat16_ent_ops;
		break;
	case FAT12:
		fsi->fatent_ops = &fat12_ent_ops;
		break;
	default:
		fsi->fatent_ops = NULL;
		EMSG("Unknown volume type : %d", (int)fsi->vol_type);
		return -ENOTSUPP;
	}

	return 0;
}

static inline bool is_reserved_clus(u32 clus)
{
	if (IS_CLUS_FREE(clus))
		return true;
	if (IS_CLUS_EOF(clus))
		return true;
	if (IS_CLUS_BAD(clus))
		return true;
	return false;
}

s32 fat_ent_get(struct super_block *sb, u32 loc, u32 *content)
{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	s32 err;

	if (!is_valid_clus(fsi, loc)) {
		sdfat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", loc);
		return -EIO;
	}

	err = fsi->fatent_ops->ent_get(sb, loc, content);
	if (err) {
		sdfat_fs_error(sb, "failed to access to FAT "
				"(entry 0x%08x, err:%d)", loc, err);
		return err;
	}

	if (!is_reserved_clus(*content) && !is_valid_clus(fsi, *content)) {
		sdfat_fs_error(sb, "invalid access to FAT (entry 0x%08x) "
			"bogus content (0x%08x)", loc, *content);
		return -EIO;
	}

	return 0;
}

s32 fat_ent_set(struct super_block *sb, u32 loc, u32 content)
{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	return fsi->fatent_ops->ent_set(sb, loc, content);
}

s32 fat_ent_get_safe(struct super_block *sb, u32 loc, u32 *content)
{
	s32 err = fat_ent_get(sb, loc, content);

	if (err)
		return err;

	if (IS_CLUS_FREE(*content)) {
		sdfat_fs_error(sb, "invalid access to FAT free cluster "
				"(entry 0x%08x)", loc);
		return -EIO;
	}

	if (IS_CLUS_BAD(*content)) {
		sdfat_fs_error(sb, "invalid access to FAT bad cluster "
				"(entry 0x%08x)", loc);
		return -EIO;
	}

	return 0;
}

/* end of fatent.c */
Commit	Line	Data
45e430a1 PK	1	/*
	2	* Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public License
	6	* as published by the Free Software Foundation; either version 2
	7	* of the License, or (at your option) any later version.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; if not, see <http://www.gnu.org/licenses/>.
	16	*/
	17
	18	/************************************************************************/
	19	/* */
	20	/* PROJECT : exFAT & FAT12/16/32 File System */
	21	/* FILE : fatent.c */
	22	/* PURPOSE : sdFAT FAT entry manager */
	23	/* */
	24	/----------------------------------------------------------------------/
	25	/* NOTES */
	26	/* */
	27	/* */
	28	/************************************************************************/
	29
	30	#include <asm/unaligned.h>
	31
	32	#include "sdfat.h"
	33	#include "core.h"
	34
	35	/----------------------------------------------------------------------/
	36	/* Global Variable Definitions */
	37	/----------------------------------------------------------------------/
	38	/* All buffer structures are protected w/ fsi->v_sem */
	39
	40	/----------------------------------------------------------------------/
	41	/* Static functions */
	42	/----------------------------------------------------------------------/
	43
	44	/======================================================================/
	45	/* FAT Read/Write Functions */
	46	/======================================================================/
	47	/* in : sb, loc
	48	* out: content
	49	* returns 0 on success, -1 on error
	50	*/
	51	static s32 exfat_ent_get(struct super_block sb, u32 loc, u32 content)
	52	{
e9692b33 PK	53	u32 off, _content;
e9692b33 PK	54	u64 sec;
45e430a1 PK	55	u8 *fat_sector;
	56	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	57
	58	/* fsi->vol_type == EXFAT */
	59	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-2));
	60	off = (loc << 2) & (u32)(sb->s_blocksize - 1);
	61
	62	fat_sector = fcache_getblk(sb, sec);
	63	if (!fat_sector)
	64	return -EIO;
	65
	66	_content = le32_to_cpu((__le32 )(&fat_sector[off]));
	67
	68	/* remap reserved clusters to simplify code */
	69	if (_content >= CLUSTER_32(0xFFFFFFF8))
	70	_content = CLUS_EOF;
	71
	72	*content = CLUSTER_32(_content);
	73	return 0;
	74	}
	75
	76	static s32 exfat_ent_set(struct super_block *sb, u32 loc, u32 content)
	77	{
e9692b33 PK	78	u32 off;
e9692b33 PK	79	u64 sec;
45e430a1 PK	80	u8 *fat_sector;
	81	__le32 *fat_entry;
	82	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	83
	84	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-2));
	85	off = (loc << 2) & (u32)(sb->s_blocksize - 1);
	86
	87	fat_sector = fcache_getblk(sb, sec);
	88	if (!fat_sector)
	89	return -EIO;
	90
	91	fat_entry = (__le32 *)&(fat_sector[off]);
	92	*fat_entry = cpu_to_le32(content);
	93
	94	return fcache_modify(sb, sec);
	95	}
	96
	97	#define FATENT_FAT32_VALID_MASK (0x0FFFFFFFU)
	98	#define FATENT_FAT32_IGNORE_MASK (0xF0000000U)
	99	static s32 fat32_ent_get(struct super_block sb, u32 loc, u32 content)
	100	{
e9692b33 PK	101	u32 off, _content;
e9692b33 PK	102	u64 sec;
45e430a1 PK	103	u8 *fat_sector;
	104	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	105
	106	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-2));
	107	off = (loc << 2) & (u32)(sb->s_blocksize - 1);
	108
	109	fat_sector = fcache_getblk(sb, sec);
	110	if (!fat_sector)
	111	return -EIO;
	112
	113	_content = le32_to_cpu((__le32 )(&fat_sector[off]));
	114	_content &= FATENT_FAT32_VALID_MASK;
	115
	116	/* remap reserved clusters to simplify code */
	117	if (_content == CLUSTER_32(0x0FFFFFF7U))
	118	_content = CLUS_BAD;
	119	else if (_content >= CLUSTER_32(0x0FFFFFF8U))
	120	_content = CLUS_EOF;
	121
	122	*content = CLUSTER_32(_content);
	123	return 0;
	124	}
	125
	126	static s32 fat32_ent_set(struct super_block *sb, u32 loc, u32 content)
	127	{
e9692b33 PK	128	u32 off;
e9692b33 PK	129	u64 sec;
45e430a1 PK	130	u8 *fat_sector;
	131	__le32 *fat_entry;
	132	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	133
	134	content &= FATENT_FAT32_VALID_MASK;
	135
	136	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-2));
	137	off = (loc << 2) & (u32)(sb->s_blocksize - 1);
	138
	139	fat_sector = fcache_getblk(sb, sec);
	140	if (!fat_sector)
	141	return -EIO;
	142
	143	fat_entry = (__le32 *)&(fat_sector[off]);
	144	content \|= (le32_to_cpu(*fat_entry) & FATENT_FAT32_IGNORE_MASK);
	145	*fat_entry = cpu_to_le32(content);
	146
	147	return fcache_modify(sb, sec);
	148	}
	149
	150	#define FATENT_FAT16_VALID_MASK (0x0000FFFFU)
	151	static s32 fat16_ent_get(struct super_block sb, u32 loc, u32 content)
	152	{
e9692b33 PK	153	u32 off, _content;
e9692b33 PK	154	u64 sec;
45e430a1 PK	155	u8 *fat_sector;
	156	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	157
	158	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-1));
	159	off = (loc << 1) & (u32)(sb->s_blocksize - 1);
	160
	161	fat_sector = fcache_getblk(sb, sec);
	162	if (!fat_sector)
	163	return -EIO;
	164
	165	_content = (u32)le16_to_cpu((__le16 )(&fat_sector[off]));
	166	_content &= FATENT_FAT16_VALID_MASK;
	167
	168	/* remap reserved clusters to simplify code */
	169	if (_content == CLUSTER_16(0xFFF7U))
	170	_content = CLUS_BAD;
	171	else if (_content >= CLUSTER_16(0xFFF8U))
	172	_content = CLUS_EOF;
	173
	174	*content = CLUSTER_32(_content);
	175	return 0;
	176	}
	177
	178	static s32 fat16_ent_set(struct super_block *sb, u32 loc, u32 content)
	179	{
e9692b33 PK	180	u32 off;
e9692b33 PK	181	u64 sec;
45e430a1 PK	182	u8 *fat_sector;
	183	__le16 *fat_entry;
	184	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	185
	186	content &= FATENT_FAT16_VALID_MASK;
	187
	188	sec = fsi->FAT1_start_sector + (loc >> (sb->s_blocksize_bits-1));
	189	off = (loc << 1) & (u32)(sb->s_blocksize - 1);
	190
	191	fat_sector = fcache_getblk(sb, sec);
	192	if (!fat_sector)
	193	return -EIO;
	194
	195	fat_entry = (__le16 *)&(fat_sector[off]);
	196	*fat_entry = cpu_to_le16(content);
	197
	198	return fcache_modify(sb, sec);
	199	}
	200
	201	#define FATENT_FAT12_VALID_MASK (0x00000FFFU)
	202	static s32 fat12_ent_get(struct super_block sb, u32 loc, u32 content)
	203	{
e9692b33 PK	204	u32 off, _content;
e9692b33 PK	205	u64 sec;
45e430a1 PK	206	u8 *fat_sector;
	207	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	208
	209	sec = fsi->FAT1_start_sector + ((loc + (loc >> 1)) >> sb->s_blocksize_bits);
	210	off = (loc + (loc >> 1)) & (u32)(sb->s_blocksize - 1);
	211
	212	fat_sector = fcache_getblk(sb, sec);
	213	if (!fat_sector)
	214	return -EIO;
	215
	216	if (off == (u32)(sb->s_blocksize - 1)) {
	217	_content = (u32) fat_sector[off];
	218
	219	fat_sector = fcache_getblk(sb, ++sec);
	220	if (!fat_sector)
	221	return -EIO;
	222
	223	_content \|= (u32) fat_sector[0] << 8;
	224	} else {
	225	_content = get_unaligned_le16(&fat_sector[off]);
	226	}
	227
	228	if (loc & 1)
	229	_content >>= 4;
	230
	231	_content &= FATENT_FAT12_VALID_MASK;
	232
	233	/* remap reserved clusters to simplify code */
	234	if (_content == CLUSTER_16(0x0FF7U))
	235	_content = CLUS_BAD;
	236	else if (_content >= CLUSTER_16(0x0FF8U))
	237	_content = CLUS_EOF;
	238
	239	*content = CLUSTER_32(_content);
	240	return 0;
	241	}
	242
	243	static s32 fat12_ent_set(struct super_block *sb, u32 loc, u32 content)
	244	{
e9692b33 PK	245	u32 off;
e9692b33 PK	246	u64 sec;
45e430a1 PK	247	u8 fat_sector, fat_entry;
	248	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	249
	250	content &= FATENT_FAT12_VALID_MASK;
	251
	252	sec = fsi->FAT1_start_sector + ((loc + (loc >> 1)) >> sb->s_blocksize_bits);
	253	off = (loc + (loc >> 1)) & (u32)(sb->s_blocksize - 1);
	254
	255	fat_sector = fcache_getblk(sb, sec);
	256	if (!fat_sector)
	257	return -EIO;
	258
	259	if (loc & 1) { /* odd */
	260
	261	content <<= 4;
	262
	263	if (off == (u32)(sb->s_blocksize-1)) {
	264	fat_sector[off] = (u8)(content \| (fat_sector[off] & 0x0F));
	265	if (fcache_modify(sb, sec))
	266	return -EIO;
	267
	268	fat_sector = fcache_getblk(sb, ++sec);
	269	if (!fat_sector)
	270	return -EIO;
	271
	272	fat_sector[0] = (u8)(content >> 8);
	273	} else {
	274	fat_entry = &(fat_sector[off]);
	275	content \|= 0x000F & get_unaligned_le16(fat_entry);
	276	put_unaligned_le16(content, fat_entry);
	277	}
	278	} else { /* even */
	279	fat_sector[off] = (u8)(content);
	280
	281	if (off == (u32)(sb->s_blocksize-1)) {
	282	fat_sector[off] = (u8)(content);
	283	if (fcache_modify(sb, sec))
	284	return -EIO;
	285
	286	fat_sector = fcache_getblk(sb, ++sec);
	287	if (!fat_sector)
	288	return -EIO;
	289
	290	fat_sector[0] = (u8)((fat_sector[0] & 0xF0) \| (content >> 8));
	291	} else {
	292	fat_entry = &(fat_sector[off]);
	293	content \|= 0xF000 & get_unaligned_le16(fat_entry);
	294	put_unaligned_le16(content, fat_entry);
	295	}
	296	}
	297	return fcache_modify(sb, sec);
	298	}
	299
	300
	301	static FATENT_OPS_T fat12_ent_ops = {
	302	fat12_ent_get,
	303	fat12_ent_set
	304	};
	305
	306	static FATENT_OPS_T fat16_ent_ops = {
	307	fat16_ent_get,
	308	fat16_ent_set
	309	};
	310
311	static FATENT_OPS_T fat32_ent_ops = {
312	fat32_ent_get,
313	fat32_ent_set
314	};
315
316	static FATENT_OPS_T exfat_ent_ops = {
317	exfat_ent_get,
318	exfat_ent_set
319	};
320
321	s32 fat_ent_ops_init(struct super_block *sb)
322	{
323	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
324
325	switch (fsi->vol_type) {
326	case EXFAT:
327	fsi->fatent_ops = &exfat_ent_ops;
328	break;
329	case FAT32:
330	fsi->fatent_ops = &fat32_ent_ops;
331	break;
332	case FAT16:
333	fsi->fatent_ops = &fat16_ent_ops;
334	break;
335	case FAT12:
336	fsi->fatent_ops = &fat12_ent_ops;
337	break;
338	default:
339	fsi->fatent_ops = NULL;
340	EMSG("Unknown volume type : %d", (int)fsi->vol_type);
341	return -ENOTSUPP;
342	}
343
344	return 0;
345	}
346
347	static inline bool is_reserved_clus(u32 clus)
348	{
349	if (IS_CLUS_FREE(clus))
350	return true;
351	if (IS_CLUS_EOF(clus))
352	return true;
353	if (IS_CLUS_BAD(clus))
354	return true;
355	return false;
356	}
357
45e430a1 PK	358	s32 fat_ent_get(struct super_block sb, u32 loc, u32 content)
	359	{
	360	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	361	s32 err;
	362
	363	if (!is_valid_clus(fsi, loc)) {
	364	sdfat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", loc);
	365	return -EIO;
	366	}
	367
	368	err = fsi->fatent_ops->ent_get(sb, loc, content);
	369	if (err) {
	370	sdfat_fs_error(sb, "failed to access to FAT "
	371	"(entry 0x%08x, err:%d)", loc, err);
	372	return err;
	373	}
	374
	375	if (!is_reserved_clus(content) && !is_valid_clus(fsi, content)) {
	376	sdfat_fs_error(sb, "invalid access to FAT (entry 0x%08x) "
	377	"bogus content (0x%08x)", loc, *content);
	378	return -EIO;
	379	}
	380
	381	return 0;
	382	}
	383
	384	s32 fat_ent_set(struct super_block *sb, u32 loc, u32 content)
	385	{
	386	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	387
	388	return fsi->fatent_ops->ent_set(sb, loc, content);
	389	}
	390
	391	s32 fat_ent_get_safe(struct super_block sb, u32 loc, u32 content)
	392	{
	393	s32 err = fat_ent_get(sb, loc, content);
	394
	395	if (err)
	396	return err;
	397
	398	if (IS_CLUS_FREE(*content)) {
	399	sdfat_fs_error(sb, "invalid access to FAT free cluster "
	400	"(entry 0x%08x)", loc);
	401	return -EIO;
	402	}
	403
	404	if (IS_CLUS_BAD(*content)) {
	405	sdfat_fs_error(sb, "invalid access to FAT bad cluster "
	406	"(entry 0x%08x)", loc);
	407	return -EIO;
	408	}
	409
	410	return 0;
	411	}
	412
	413	/* end of fatent.c */