fs, net: Move read_descriptor_t to net.h

fs.h has no more need for this typedef; networking is now the sole user
of the read_descriptor_t.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/net.h

@@ -125,6 +125,25 @@ struct socket {
 	struct socket_wq	wq;
 };
 
+/*
+ * "descriptor" for what we're up to with a read.
+ * This allows us to use the same read code yet
+ * have multiple different users of the data that
+ * we read from a file.
+ *
+ * The simplest case just copies the data to user
+ * mode.
+ */
+typedef struct {
+	size_t written;
+	size_t count;
+	union {
+		char __user *buf;
+		void *data;
+	} arg;
+	int error;
+} read_descriptor_t;
+
 struct vm_area_struct;
 struct page;
 struct sockaddr;