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-specification

Signed-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.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 136 insertions, 0 deletions

diff --git a/drivers/staging/exfat/exfat_blkdev.c b/drivers/staging/exfat/exfat_blkdev.c
new file mode 100644
index 000000000000..f086c75e7076
--- /dev/null
+++ b/drivers/staging/exfat/exfat_blkdev.c
@@ -0,0 +1,136 @@
+// 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);
+}