[PATCH] fbdev: Fix return error of fb_write

Fix return code of fb_write():

If at least 1 byte was transferred to the device, return number of bytes,
otherwise:

    - return -EFBIG - if file offset is past the maximum allowable offset or
      size is greater than framebuffer length
    - return -ENOSPC - if size is greater than framebuffer length - offset
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/video/fbmem.c

@@ -669,13 +669,19 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 		total_size = info->fix.smem_len;
 
 	if (p > total_size)
-		return 0;
+		return -EFBIG;
 
-	if (count >= total_size)
+	if (count > total_size) {
+		err = -EFBIG;
 		count = total_size;
+	}
+
+	if (count + p > total_size) {
+		if (!err)
+			err = -ENOSPC;
 
-	if (count + p > total_size)
 		count = total_size - p;
+	}
 
 	buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
 			 GFP_KERNEL);
@@ -717,7 +723,7 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 
 	kfree(buffer);
 
-	return (err) ? err : cnt;
+	return (cnt) ? cnt : err;
 }
 
 #ifdef CONFIG_KMOD