ADD file via upload

fs/file_dev.c

@@ -0,0 +1,90 @@
+/*
+ *  linux/fs/file_dev.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <asm/segment.h>
+
+#define MIN(a,b) (((a)<(b))?(a):(b))
+#define MAX(a,b) (((a)>(b))?(a):(b))
+
+int file_read(struct m_inode * inode, struct file * filp, char * buf, int count)
+{
+	int left,chars,nr;
+	struct buffer_head * bh;
+
+	if ((left=count)<=0)
+		return 0;
+	while (left) {
+		if (nr = bmap(inode,(filp->f_pos)/BLOCK_SIZE)) {
+			if (!(bh=bread(inode->i_dev,nr)))
+				break;
+		} else
+			bh = NULL;
+		nr = filp->f_pos % BLOCK_SIZE;
+		chars = MIN( BLOCK_SIZE-nr , left );
+		filp->f_pos += chars;
+		left -= chars;
+		if (bh) {
+			char * p = nr + bh->b_data;
+			while (chars-->0)
+				put_fs_byte(*(p++),buf++);
+			brelse(bh);
+		} else {
+			while (chars-->0)
+				put_fs_byte(0,buf++);
+		}
+	}
+	inode->i_atime = CURRENT_TIME;
+	return (count-left)?(count-left):-ERROR;
+}
+
+int file_write(struct m_inode * inode, struct file * filp, char * buf, int count)
+{
+	off_t pos;
+	int block,c;
+	struct buffer_head * bh;
+	char * p;
+	int i=0;
+
+/*
+ * ok, append may not work when many processes are writing at the same time
+ * but so what. That way leads to madness anyway.
+ */
+	if (filp->f_flags & O_APPEND)
+		pos = inode->i_size;
+	else
+		pos = filp->f_pos;
+	while (i<count) {
+		if (!(block = create_block(inode,pos/BLOCK_SIZE)))
+			break;
+		if (!(bh=bread(inode->i_dev,block)))
+			break;
+		c = pos % BLOCK_SIZE;
+		p = c + bh->b_data;
+		bh->b_dirt = 1;
+		c = BLOCK_SIZE-c;
+		if (c > count-i) c = count-i;
+		pos += c;
+		if (pos > inode->i_size) {
+			inode->i_size = pos;
+			inode->i_dirt = 1;
+		}
+		i += c;
+		while (c-->0)
+			*(p++) = get_fs_byte(buf++);
+		brelse(bh);
+	}
+	inode->i_mtime = CURRENT_TIME;
+	if (!(filp->f_flags & O_APPEND)) {
+		filp->f_pos = pos;
+		inode->i_ctime = CURRENT_TIME;
+	}
+	return (i?i:-1);
+}