From 723428bebe3105ad3c3406e416402d1831b482c4 Mon Sep 17 00:00:00 2001
From: Andrew Lee <alee14498@protonmail.com>
Date: Sun, 15 Aug 2021 00:16:45 -0400
Subject: Inital commit

---
 linux/fs/block_dev.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 linux/fs/block_dev.c

(limited to 'linux/fs/block_dev.c')

diff --git a/linux/fs/block_dev.c b/linux/fs/block_dev.c
new file mode 100644
index 0000000..7bbae6a
--- /dev/null
+++ b/linux/fs/block_dev.c
@@ -0,0 +1,86 @@
+#include <errno.h>
+
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <asm/segment.h>
+
+#define NR_BLK_DEV ((sizeof (rd_blk))/(sizeof (rd_blk[0])))
+
+int block_write(int dev, long * pos, char * buf, int count)
+{
+	int block = *pos / BLOCK_SIZE;
+	int offset = *pos % BLOCK_SIZE;
+	int chars;
+	int written = 0;
+	struct buffer_head * bh;
+	register char * p;
+
+	while (count>0) {
+		bh = bread(dev,block);
+		if (!bh)
+			return written?written:-EIO;
+		chars = (count<BLOCK_SIZE) ? count : BLOCK_SIZE;
+		p = offset + bh->b_data;
+		offset = 0;
+		block++;
+		*pos += chars;
+		written += chars;
+		count -= chars;
+		while (chars-->0)
+			*(p++) = get_fs_byte(buf++);
+		bh->b_dirt = 1;
+		brelse(bh);
+	}
+	return written;
+}
+
+int block_read(int dev, unsigned long * pos, char * buf, int count)
+{
+	int block = *pos / BLOCK_SIZE;
+	int offset = *pos % BLOCK_SIZE;
+	int chars;
+	int read = 0;
+	struct buffer_head * bh;
+	register char * p;
+
+	while (count>0) {
+		bh = bread(dev,block);
+		if (!bh)
+			return read?read:-EIO;
+		chars = (count<BLOCK_SIZE) ? count : BLOCK_SIZE;
+		p = offset + bh->b_data;
+		offset = 0;
+		block++;
+		*pos += chars;
+		read += chars;
+		count -= chars;
+		while (chars-->0)
+			put_fs_byte(*(p++),buf++);
+		bh->b_dirt = 1;
+		brelse(bh);
+	}
+	return read;
+}
+
+extern void rw_hd(int rw, struct buffer_head * bh);
+
+typedef void (*blk_fn)(int rw, struct buffer_head * bh);
+
+static blk_fn rd_blk[]={
+	NULL,		/* nodev */
+	NULL,		/* dev mem */
+	NULL,		/* dev fd */
+	rw_hd,		/* dev hd */
+	NULL,		/* dev ttyx */
+	NULL,		/* dev tty */
+	NULL};		/* dev lp */
+
+void ll_rw_block(int rw, struct buffer_head * bh)
+{
+	blk_fn blk_addr;
+	unsigned int major;
+
+	if ((major=MAJOR(bh->b_dev)) >= NR_BLK_DEV || !(blk_addr=rd_blk[major]))
+		panic("Trying to read nonexistent block-device");
+	blk_addr(rw, bh);
+}
-- 
cgit v1.2.3