ADD file via upload

fs/block_dev.c

@@ -0,0 +1,73 @@
+/*
+ *  linux/fs/block_dev.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+#include <errno.h>
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <asm/segment.h>
+#include <asm/system.h>
+
+int block_write(int dev, long * pos, char * buf, int count)
+{
+	int block = *pos >> BLOCK_SIZE_BITS;
+	int offset = *pos & (BLOCK_SIZE-1);
+	int chars;
+	int written = 0;
+	struct buffer_head * bh;
+	register char * p;
+
+	while (count>0) {
+		chars = BLOCK_SIZE - offset;
+		if (chars > count)
+			chars=count;
+		if (chars == BLOCK_SIZE)
+			bh = getblk(dev,block);
+		else
+			bh = breada(dev,block,block+1,block+2,-1);
+		block++;
+		if (!bh)
+			return written?written:-EIO;
+		p = offset + bh->b_data;
+		offset = 0;
+		*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_BITS;
+	int offset = *pos & (BLOCK_SIZE-1);
+	int chars;
+	int read = 0;
+	struct buffer_head * bh;
+	register char * p;
+
+	while (count>0) {
+		chars = BLOCK_SIZE-offset;
+		if (chars > count)
+			chars = count;
+		if (!(bh = breada(dev,block,block+1,block+2,-1)))
+			return read?read:-EIO;
+		block++;
+		p = offset + bh->b_data;
+		offset = 0;
+		*pos += chars;
+		read += chars;
+		count -= chars;
+		while (chars-->0)
+			put_fs_byte(*(p++),buf++);
+		brelse(bh);
+	}
+	return read;
+}