fs/sdfat/blkdev.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  *  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    : blkdev.c                                                  */
 /*  PURPOSE : sdFAT Block Device Driver Glue Layer                      */
 /*                                                                      */
 /*----------------------------------------------------------------------*/
 /*  NOTES                                                               */
 /*                                                                      */
 /************************************************************************/

 #include <linux/blkdev.h>
 #include <linux/log2.h>
 #include <linux/backing-dev.h>

 #include "sdfat.h"

 /*----------------------------------------------------------------------*/
 /*  Constant & Macro Definitions                                        */
 /*----------------------------------------------------------------------*/

 /*----------------------------------------------------------------------*/
 /*  Global Variable Definitions                                         */
 /*----------------------------------------------------------------------*/

 /*----------------------------------------------------------------------*/
 /*  Local Variable Definitions                                          */
 /*----------------------------------------------------------------------*/

 /*----------------------------------------------------------------------*/
 /*  FUNCTIONS WHICH HAS KERNEL VERSION DEPENDENCY                       */
 /************************************************************************/

 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 0, 0)
 	/* EMPTY */
 #else /* LINUX_VERSION_CODE < KERNEL_VERSION(4, 0, 0) */
 static struct backing_dev_info *inode_to_bdi(struct inode *bd_inode)
 {
 	return bd_inode->i_mapping->backing_dev_info;
 }
 #endif

 /*======================================================================*/
 /*  Function Definitions                                                */
 /*======================================================================*/
 s32 bdev_open_dev(struct super_block *sb)
 {
 	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

 	if (fsi->bd_opened)
 		return 0;

 	fsi->bd_opened = true;
 	return 0;
 }

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

 	fsi->bd_opened = false;
 	return 0;
 }

 static inline s32 block_device_ejected(struct super_block *sb)
 {
 	struct inode *bd_inode = sb->s_bdev->bd_inode;
 	struct backing_dev_info *bdi = inode_to_bdi(bd_inode);

 	return (bdi->dev == NULL);
 }

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

 	if (block_device_ejected(sb)) {
 		if (!(fsi->prev_eio & SDFAT_EIO_BDI)) {
 			fsi->prev_eio |= SDFAT_EIO_BDI;
 			sdfat_log_msg(sb, KERN_ERR, "%s: block device is "
 				"eliminated.(bdi:%p)", __func__, sb->s_bdi);
 		}
 		return -ENXIO;
 	}

 	return 0;
 }

 #if IS_BUILTIN(CONFIG_SDFAT_FS)
 static void __bdev_readahead(struct super_block *sb, u64 secno, u64 num_secs)
 {
 	u32 sects_per_page = (PAGE_SIZE >> sb->s_blocksize_bits);
 	struct blk_plug plug;
 	u64 i;

 	blk_start_plug(&plug);
 	for (i = 0; i < num_secs; i++) {
 		if (i && !(i & (sects_per_page - 1)))
 			blk_flush_plug(current);
 		sb_breadahead(sb, (sector_t)(secno + i));
 	}
 	blk_finish_plug(&plug);
 }
 #else
 static void __bdev_readahead(struct super_block *sb, u64 secno, u64 num_secs)
 {
 	u64 i;

 	for (i = 0; i < num_secs; i++)
 		sb_breadahead(sb, (sector_t)(secno + i));
 }
 #endif

 /* Make a readahead request */
 s32 bdev_readahead(struct super_block *sb, u64 secno, u64 num_secs)
 {
 	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

 	if (!fsi->bd_opened)
 		return -EIO;

 	__bdev_readahead(sb, secno, num_secs);

 	return 0;
 }

 s32 bdev_mread(struct super_block *sb, u64 secno, struct buffer_head **bh, u64 num_secs, s32 read)
 {
 	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
 	u8 blksize_bits = sb->s_blocksize_bits;
 #ifdef CONFIG_SDFAT_DBG_IOCTL
 	struct sdfat_sb_info *sbi = SDFAT_SB(sb);
 	long flags = sbi->debug_flags;

 	if (flags & SDFAT_DEBUGFLAGS_ERROR_RW)
 		return -EIO;
 #endif /* CONFIG_SDFAT_DBG_IOCTL */

 	if (!fsi->bd_opened)
 		return -EIO;

 	brelse(*bh);

 	if (read)
 		*bh = __bread(sb->s_bdev, (sector_t)secno, num_secs << blksize_bits);
 	else
 		*bh = __getblk(sb->s_bdev, (sector_t)secno, num_secs << blksize_bits);

 	/* read successfully */
 	if (*bh)
 		return 0;

 	/*
 	 * patch 1.2.4 : reset ONCE warning message per volume.
 	 */
 	if (!(fsi->prev_eio & SDFAT_EIO_READ)) {
 		fsi->prev_eio |= SDFAT_EIO_READ;
 		sdfat_log_msg(sb, KERN_ERR, "%s: No bh. I/O error.", __func__);
 		sdfat_debug_warn_on(1);
 	}

 	return -EIO;
 }

 s32 bdev_mwrite(struct super_block *sb, u64 secno, struct buffer_head *bh, u64 num_secs, s32 sync)
 {
 	u64 count;
 	struct buffer_head *bh2;
 	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
 #ifdef CONFIG_SDFAT_DBG_IOCTL
 	struct sdfat_sb_info *sbi = SDFAT_SB(sb);
 	long flags = sbi->debug_flags;

 	if (flags & SDFAT_DEBUGFLAGS_ERROR_RW)
 		return -EIO;
 #endif /* CONFIG_SDFAT_DBG_IOCTL */

 	if (!fsi->bd_opened)
 		return -EIO;

 	if (secno == bh->b_blocknr) {
 		set_buffer_uptodate(bh);
 		mark_buffer_dirty(bh);
 		if (sync && (sync_dirty_buffer(bh) != 0))
 			return -EIO;
 	} else {
 		count = num_secs << sb->s_blocksize_bits;

 		bh2 = __getblk(sb->s_bdev, (sector_t)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:
 	/*
 	 * patch 1.2.4 : reset ONCE warning message per volume.
 	 */
 	if (!(fsi->prev_eio & SDFAT_EIO_WRITE)) {
 		fsi->prev_eio |= SDFAT_EIO_WRITE;
 		sdfat_log_msg(sb, KERN_ERR, "%s: No bh. I/O error.", __func__);
 		sdfat_debug_warn_on(1);
 	}

 	return -EIO;
 }

 s32 bdev_sync_all(struct super_block *sb)
 {
 	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
 #ifdef CONFIG_SDFAT_DBG_IOCTL
 	struct sdfat_sb_info *sbi = SDFAT_SB(sb);
 	long flags = sbi->debug_flags;

 	if (flags & SDFAT_DEBUGFLAGS_ERROR_RW)
 		return -EIO;
 #endif /* CONFIG_SDFAT_DBG_IOCTL */

 	if (!fsi->bd_opened)
 		return -EIO;

 	return sync_blockdev(sb->s_bdev);
 }

 /*
  *  Sector Read/Write Functions
  */
 s32 read_sect(struct super_block *sb, u64 sec, struct buffer_head **bh, s32 read)
 {
 	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

 	BUG_ON(!bh);
 	if ((sec >= fsi->num_sectors) && (fsi->num_sectors > 0)) {
 		sdfat_fs_error_ratelimit(sb,
 				"%s: out of range (sect:%llu)", __func__, sec);
 		return -EIO;
 	}

 	if (bdev_mread(sb, sec, bh, 1, read)) {
 		sdfat_fs_error_ratelimit(sb,
 				"%s: I/O error (sect:%llu)", __func__, sec);
 		return -EIO;
 	}

 	return 0;
 }

 s32 write_sect(struct super_block *sb, u64 sec, struct buffer_head *bh, s32 sync)
 {
 	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

 	BUG_ON(!bh);
 	if ((sec >= fsi->num_sectors) && (fsi->num_sectors > 0)) {
 		sdfat_fs_error_ratelimit(sb,
 				"%s: out of range (sect:%llu)", __func__, sec);
 		return -EIO;
 	}

 	if (bdev_mwrite(sb, sec, bh, 1, sync)) {
 		sdfat_fs_error_ratelimit(sb, "%s: I/O error (sect:%llu)",
 						__func__, sec);
 		return -EIO;
 	}

 	return 0;
 }

 s32 read_msect(struct super_block *sb, u64 sec, struct buffer_head **bh, u64 num_secs, s32 read)
 {
 	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

 	BUG_ON(!bh);
 	if (((sec+num_secs) > fsi->num_sectors) && (fsi->num_sectors > 0)) {
 		sdfat_fs_error_ratelimit(sb, "%s: out of range(sect:%llu len:%llu)",
 						__func__, sec, num_secs);
 		return -EIO;
 	}

 	if (bdev_mread(sb, sec, bh, num_secs, read)) {
 		sdfat_fs_error_ratelimit(sb, "%s: I/O error (sect:%llu len:%llu)",
 						__func__, sec, num_secs);
 		return -EIO;
 	}

 	return 0;
 }

 s32 write_msect(struct super_block *sb, u64 sec, struct buffer_head *bh, u64 num_secs, s32 sync)
 {
 	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

 	BUG_ON(!bh);
 	if (((sec+num_secs) > fsi->num_sectors) && (fsi->num_sectors > 0)) {
 		sdfat_fs_error_ratelimit(sb, "%s: out of range(sect:%llu len:%llu)",
 						__func__, sec, num_secs);
 		return -EIO;
 	}


 	if (bdev_mwrite(sb, sec, bh, num_secs, sync)) {
 		sdfat_fs_error_ratelimit(sb, "%s: I/O error (sect:%llu len:%llu)",
 						__func__, sec, num_secs);
 		return -EIO;
 	}

 	return 0;
 }

 static inline void __blkdev_write_bhs(struct buffer_head **bhs, s32 nr_bhs)
 {
 	s32 i;

 	for (i = 0; i < nr_bhs; i++)
 		write_dirty_buffer(bhs[i], WRITE);
 }

 static inline s32 __blkdev_sync_bhs(struct buffer_head **bhs, s32 nr_bhs)
 {
 	s32 i, err = 0;

 	for (i = 0; i < nr_bhs; i++) {
 		wait_on_buffer(bhs[i]);
 		if (!err && !buffer_uptodate(bhs[i]))
 			err = -EIO;
 	}
 	return err;
 }

 static inline s32 __buffer_zeroed(struct super_block *sb, u64 blknr, u64 num_secs)
 {
 	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
 	s32 nr_bhs = MAX_BUF_PER_PAGE;
 	u64 last_blknr = blknr + num_secs;
 	s32 err, i, n;
 	struct blk_plug plug;

 	/* Zeroing the unused blocks on this cluster */
 	n = 0;
 	blk_start_plug(&plug);
 	while (blknr < last_blknr) {
 		bhs[n] = sb_getblk(sb, (sector_t)blknr);
 		if (!bhs[n]) {
 			err = -ENOMEM;
 			blk_finish_plug(&plug);
 			goto error;
 		}
 		memset(bhs[n]->b_data, 0, sb->s_blocksize);
 		set_buffer_uptodate(bhs[n]);
 		mark_buffer_dirty(bhs[n]);

 		n++;
 		blknr++;

 		if (blknr == last_blknr)
 			break;

 		if (n == nr_bhs) {
 			__blkdev_write_bhs(bhs, n);

 			for (i = 0; i < n; i++)
 				brelse(bhs[i]);
 			n = 0;
 		}
 	}
 	__blkdev_write_bhs(bhs, n);
 	blk_finish_plug(&plug);

 	err = __blkdev_sync_bhs(bhs, n);
 	if (err)
 		goto error;

 	for (i = 0; i < n; i++)
 		brelse(bhs[i]);

 	return 0;

 error:
 	EMSG("%s: failed zeroed sect %llu\n", __func__, blknr);
 	for (i = 0; i < n; i++)
 		bforget(bhs[i]);

 	return err;
 }

 s32 write_msect_zero(struct super_block *sb, u64 sec, u64 num_secs)
 {
 	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

 	if (((sec+num_secs) > fsi->num_sectors) && (fsi->num_sectors > 0)) {
 		sdfat_fs_error_ratelimit(sb, "%s: out of range(sect:%llu len:%llu)",
 						__func__, sec, num_secs);
 		return -EIO;
 	}

 	/* Just return -EAGAIN if it is failed */
 	if (__buffer_zeroed(sb, sec, num_secs))
 		return -EAGAIN;

 	return 0;
 } /* end of write_msect_zero */

 /* end of blkdev.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 : blkdev.c */
	/* PURPOSE : sdFAT Block Device Driver Glue Layer */
	/* */
	/----------------------------------------------------------------------/
	/* NOTES */
	/* */
	/************************************************************************/

	#include <linux/blkdev.h>
	#include <linux/log2.h>
	#include <linux/backing-dev.h>

	#include "sdfat.h"

	/----------------------------------------------------------------------/
	/* Constant & Macro Definitions */
	/----------------------------------------------------------------------/

	/----------------------------------------------------------------------/
	/* Global Variable Definitions */
	/----------------------------------------------------------------------/

	/----------------------------------------------------------------------/
	/* Local Variable Definitions */
	/----------------------------------------------------------------------/

	/----------------------------------------------------------------------/
	/* FUNCTIONS WHICH HAS KERNEL VERSION DEPENDENCY */
	/************************************************************************/

	#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 0, 0)
	/* EMPTY */
	#else /* LINUX_VERSION_CODE < KERNEL_VERSION(4, 0, 0) */
	static struct backing_dev_info inode_to_bdi(struct inode bd_inode)
	{
	return bd_inode->i_mapping->backing_dev_info;
	}
	#endif

	/======================================================================/
	/* Function Definitions */
	/======================================================================/
	s32 bdev_open_dev(struct super_block *sb)
	{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	if (fsi->bd_opened)
	return 0;

	fsi->bd_opened = true;
	return 0;
	}

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

	fsi->bd_opened = false;
	return 0;
	}

	static inline s32 block_device_ejected(struct super_block *sb)
	{
	struct inode *bd_inode = sb->s_bdev->bd_inode;
	struct backing_dev_info *bdi = inode_to_bdi(bd_inode);

	return (bdi->dev == NULL);
	}

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

	if (block_device_ejected(sb)) {
	if (!(fsi->prev_eio & SDFAT_EIO_BDI)) {
	fsi->prev_eio \|= SDFAT_EIO_BDI;
	sdfat_log_msg(sb, KERN_ERR, "%s: block device is "
	"eliminated.(bdi:%p)", __func__, sb->s_bdi);
	}
	return -ENXIO;
	}

	return 0;
	}

	#if IS_BUILTIN(CONFIG_SDFAT_FS)
	static void __bdev_readahead(struct super_block *sb, u64 secno, u64 num_secs)
	{
	u32 sects_per_page = (PAGE_SIZE >> sb->s_blocksize_bits);
	struct blk_plug plug;
	u64 i;

	blk_start_plug(&plug);
	for (i = 0; i < num_secs; i++) {
	if (i && !(i & (sects_per_page - 1)))
	blk_flush_plug(current);
	sb_breadahead(sb, (sector_t)(secno + i));
	}
	blk_finish_plug(&plug);
	}
	#else
	static void __bdev_readahead(struct super_block *sb, u64 secno, u64 num_secs)
	{
	u64 i;

	for (i = 0; i < num_secs; i++)
	sb_breadahead(sb, (sector_t)(secno + i));
	}
	#endif

	/* Make a readahead request */
	s32 bdev_readahead(struct super_block *sb, u64 secno, u64 num_secs)
	{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	if (!fsi->bd_opened)
	return -EIO;

	__bdev_readahead(sb, secno, num_secs);

	return 0;
	}

	s32 bdev_mread(struct super_block sb, u64 secno, struct buffer_head *bh, u64 num_secs, s32 read)
	{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	u8 blksize_bits = sb->s_blocksize_bits;
	#ifdef CONFIG_SDFAT_DBG_IOCTL
	struct sdfat_sb_info *sbi = SDFAT_SB(sb);
	long flags = sbi->debug_flags;

	if (flags & SDFAT_DEBUGFLAGS_ERROR_RW)
	return -EIO;
	#endif /* CONFIG_SDFAT_DBG_IOCTL */

	if (!fsi->bd_opened)
	return -EIO;

	brelse(*bh);

	if (read)
	*bh = __bread(sb->s_bdev, (sector_t)secno, num_secs << blksize_bits);
	else
	*bh = __getblk(sb->s_bdev, (sector_t)secno, num_secs << blksize_bits);

	/* read successfully */
	if (*bh)
	return 0;

	/*
	* patch 1.2.4 : reset ONCE warning message per volume.
	*/
	if (!(fsi->prev_eio & SDFAT_EIO_READ)) {
	fsi->prev_eio \|= SDFAT_EIO_READ;
	sdfat_log_msg(sb, KERN_ERR, "%s: No bh. I/O error.", __func__);
	sdfat_debug_warn_on(1);
	}

	return -EIO;
	}

	s32 bdev_mwrite(struct super_block sb, u64 secno, struct buffer_head bh, u64 num_secs, s32 sync)
	{
	u64 count;
	struct buffer_head *bh2;
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	#ifdef CONFIG_SDFAT_DBG_IOCTL
	struct sdfat_sb_info *sbi = SDFAT_SB(sb);
	long flags = sbi->debug_flags;

	if (flags & SDFAT_DEBUGFLAGS_ERROR_RW)
	return -EIO;
	#endif /* CONFIG_SDFAT_DBG_IOCTL */

	if (!fsi->bd_opened)
	return -EIO;

	if (secno == bh->b_blocknr) {
	set_buffer_uptodate(bh);
	mark_buffer_dirty(bh);
	if (sync && (sync_dirty_buffer(bh) != 0))
	return -EIO;
	} else {
	count = num_secs << sb->s_blocksize_bits;

	bh2 = __getblk(sb->s_bdev, (sector_t)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:
	/*
	* patch 1.2.4 : reset ONCE warning message per volume.
	*/
	if (!(fsi->prev_eio & SDFAT_EIO_WRITE)) {
	fsi->prev_eio \|= SDFAT_EIO_WRITE;
	sdfat_log_msg(sb, KERN_ERR, "%s: No bh. I/O error.", __func__);
	sdfat_debug_warn_on(1);
	}

	return -EIO;
	}

	s32 bdev_sync_all(struct super_block *sb)
	{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);
	#ifdef CONFIG_SDFAT_DBG_IOCTL
	struct sdfat_sb_info *sbi = SDFAT_SB(sb);
	long flags = sbi->debug_flags;

	if (flags & SDFAT_DEBUGFLAGS_ERROR_RW)
	return -EIO;
	#endif /* CONFIG_SDFAT_DBG_IOCTL */

	if (!fsi->bd_opened)
	return -EIO;

	return sync_blockdev(sb->s_bdev);
	}

	/*
	* Sector Read/Write Functions
	*/
	s32 read_sect(struct super_block sb, u64 sec, struct buffer_head *bh, s32 read)
	{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	BUG_ON(!bh);
	if ((sec >= fsi->num_sectors) && (fsi->num_sectors > 0)) {
	sdfat_fs_error_ratelimit(sb,
	"%s: out of range (sect:%llu)", __func__, sec);
	return -EIO;
	}

	if (bdev_mread(sb, sec, bh, 1, read)) {
	sdfat_fs_error_ratelimit(sb,
	"%s: I/O error (sect:%llu)", __func__, sec);
	return -EIO;
	}

	return 0;
	}

	s32 write_sect(struct super_block sb, u64 sec, struct buffer_head bh, s32 sync)
	{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	BUG_ON(!bh);
	if ((sec >= fsi->num_sectors) && (fsi->num_sectors > 0)) {
	sdfat_fs_error_ratelimit(sb,
	"%s: out of range (sect:%llu)", __func__, sec);
	return -EIO;
	}

	if (bdev_mwrite(sb, sec, bh, 1, sync)) {
	sdfat_fs_error_ratelimit(sb, "%s: I/O error (sect:%llu)",
	__func__, sec);
	return -EIO;
	}

	return 0;
	}

	s32 read_msect(struct super_block sb, u64 sec, struct buffer_head *bh, u64 num_secs, s32 read)
	{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	BUG_ON(!bh);
	if (((sec+num_secs) > fsi->num_sectors) && (fsi->num_sectors > 0)) {
	sdfat_fs_error_ratelimit(sb, "%s: out of range(sect:%llu len:%llu)",
	__func__, sec, num_secs);
	return -EIO;
	}

	if (bdev_mread(sb, sec, bh, num_secs, read)) {
	sdfat_fs_error_ratelimit(sb, "%s: I/O error (sect:%llu len:%llu)",
	__func__, sec, num_secs);
	return -EIO;
	}

	return 0;
	}

	s32 write_msect(struct super_block sb, u64 sec, struct buffer_head bh, u64 num_secs, s32 sync)
	{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	BUG_ON(!bh);
	if (((sec+num_secs) > fsi->num_sectors) && (fsi->num_sectors > 0)) {
	sdfat_fs_error_ratelimit(sb, "%s: out of range(sect:%llu len:%llu)",
	__func__, sec, num_secs);
	return -EIO;
	}


	if (bdev_mwrite(sb, sec, bh, num_secs, sync)) {
	sdfat_fs_error_ratelimit(sb, "%s: I/O error (sect:%llu len:%llu)",
	__func__, sec, num_secs);
	return -EIO;
	}

	return 0;
	}

	static inline void __blkdev_write_bhs(struct buffer_head **bhs, s32 nr_bhs)
	{
	s32 i;

	for (i = 0; i < nr_bhs; i++)
	write_dirty_buffer(bhs[i], WRITE);
	}

	static inline s32 __blkdev_sync_bhs(struct buffer_head **bhs, s32 nr_bhs)
	{
	s32 i, err = 0;

	for (i = 0; i < nr_bhs; i++) {
	wait_on_buffer(bhs[i]);
	if (!err && !buffer_uptodate(bhs[i]))
	err = -EIO;
	}
	return err;
	}

	static inline s32 __buffer_zeroed(struct super_block *sb, u64 blknr, u64 num_secs)
	{
	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
	s32 nr_bhs = MAX_BUF_PER_PAGE;
	u64 last_blknr = blknr + num_secs;
	s32 err, i, n;
	struct blk_plug plug;

	/* Zeroing the unused blocks on this cluster */
	n = 0;
	blk_start_plug(&plug);
	while (blknr < last_blknr) {
	bhs[n] = sb_getblk(sb, (sector_t)blknr);
	if (!bhs[n]) {
	err = -ENOMEM;
	blk_finish_plug(&plug);
	goto error;
	}
	memset(bhs[n]->b_data, 0, sb->s_blocksize);
	set_buffer_uptodate(bhs[n]);
	mark_buffer_dirty(bhs[n]);

	n++;
	blknr++;

	if (blknr == last_blknr)
	break;

	if (n == nr_bhs) {
	__blkdev_write_bhs(bhs, n);

	for (i = 0; i < n; i++)
	brelse(bhs[i]);
	n = 0;
	}
	}
	__blkdev_write_bhs(bhs, n);
	blk_finish_plug(&plug);

	err = __blkdev_sync_bhs(bhs, n);
	if (err)
	goto error;

	for (i = 0; i < n; i++)
	brelse(bhs[i]);

	return 0;

	error:
	EMSG("%s: failed zeroed sect %llu\n", __func__, blknr);
	for (i = 0; i < n; i++)
	bforget(bhs[i]);

	return err;
	}

	s32 write_msect_zero(struct super_block *sb, u64 sec, u64 num_secs)
	{
	FS_INFO_T *fsi = &(SDFAT_SB(sb)->fsi);

	if (((sec+num_secs) > fsi->num_sectors) && (fsi->num_sectors > 0)) {
	sdfat_fs_error_ratelimit(sb, "%s: out of range(sect:%llu len:%llu)",
	__func__, sec, num_secs);
	return -EIO;
	}

	/* Just return -EAGAIN if it is failed */
	if (__buffer_zeroed(sb, sec, num_secs))
	return -EAGAIN;

	return 0;
	} /* end of write_msect_zero */

	/* end of blkdev.c */