hostfs: Make hostfs_readpage more readable

...to make life easier for future readers of that code.
Signed-off-by: Richard Weinberger <richard@nod.at>

fs/hostfs/hostfs_kern.c

@@ -439,25 +439,27 @@ static int hostfs_readpage(struct file *file, struct page *page)
 {
 	char *buffer;
 	long long start;
-	int err = 0;
+	int bytes_read, ret;
 
 	start = (long long) page->index << PAGE_CACHE_SHIFT;
 	buffer = kmap(page);
-	err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
+	bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
 			PAGE_CACHE_SIZE);
-	if (err < 0)
+	if (bytes_read < 0) {
+		ret = bytes_read;
 		goto out;
+	}
 
-	memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
+	memset(buffer + bytes_read, 0, PAGE_CACHE_SIZE - bytes_read);
 
 	flush_dcache_page(page);
 	SetPageUptodate(page);
 	if (PageError(page)) ClearPageError(page);
-	err = 0;
+	ret = 0;
  out:
 	kunmap(page);
 	unlock_page(page);
-	return err;
+	return ret;
 }
 
 static int hostfs_write_begin(struct file *file, struct address_space *mapping,