[SCSI] iscsi_tcp: split module into lib and lld

As explained in the previous mails, cxgb3i needs iscsi_tcp's
r2t/data_out and data_in procesing so this just moves functions
that both drivers want to use to a new module libiscsi_tcp. The
next patch will hook iscsi_tcp in.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

include/scsi/libiscsi_tcp.h

+/*
+ * iSCSI over TCP/IP Data-Path lib
+ *
+ * Copyright (C) 2008 Mike Christie
+ * Copyright (C) 2008 Red Hat, Inc.  All rights reserved.
+ * maintained by open-iscsi@googlegroups.com
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * See the file COPYING included with this distribution for more details.
+ */
+
+#ifndef LIBISCSI_TCP_H
+#define LIBISCSI_TCP_H
+
+#include <scsi/libiscsi.h>
+
+struct iscsi_tcp_conn;
+struct iscsi_segment;
+struct sk_buff;
+struct hash_desc;
+
+typedef int iscsi_segment_done_fn_t(struct iscsi_tcp_conn *,
+				    struct iscsi_segment *);
+
+struct iscsi_segment {
+	unsigned char		*data;
+	unsigned int		size;
+	unsigned int		copied;
+	unsigned int		total_size;
+	unsigned int		total_copied;
+
+	struct hash_desc	*hash;
+	unsigned char		recv_digest[ISCSI_DIGEST_SIZE];
+	unsigned char		digest[ISCSI_DIGEST_SIZE];
+	unsigned int		digest_len;
+
+	struct scatterlist	*sg;
+	void			*sg_mapped;
+	unsigned int		sg_offset;
+
+	iscsi_segment_done_fn_t	*done;
+};
+
+/* Socket connection recieve helper */
+struct iscsi_tcp_recv {
+	struct iscsi_hdr	*hdr;
+	struct iscsi_segment	segment;
+
+	/* Allocate buffer for BHS + AHS */
+	uint32_t		hdr_buf[64];
+
+	/* copied and flipped values */
+	int			datalen;
+};
+
+struct iscsi_tcp_conn {
+	struct iscsi_conn	*iscsi_conn;
+	void			*dd_data;
+	int			stop_stage;	/* conn_stop() flag: *
+						 * stop to recover,  *
+						 * stop to terminate */
+	/* control data */
+	struct iscsi_tcp_recv	in;		/* TCP receive context */
+	/* CRC32C (Rx) LLD should set this is they do not offload */
+	struct hash_desc	*rx_hash;
+};
+
+struct iscsi_tcp_task {
+	uint32_t		exp_datasn;	/* expected target's R2TSN/DataSN */
+	int			data_offset;
+	struct iscsi_r2t_info	*r2t;		/* in progress solict R2T */
+	struct iscsi_pool	r2tpool;
+	struct kfifo		*r2tqueue;
+	void			*dd_data;
+};
+
+enum {
+	ISCSI_TCP_SEGMENT_DONE,		/* curr seg has been processed */
+	ISCSI_TCP_SKB_DONE,		/* skb is out of data */
+	ISCSI_TCP_CONN_ERR,		/* iscsi layer has fired a conn err */
+	ISCSI_TCP_SUSPENDED,		/* conn is suspended */
+};
+
+extern void iscsi_tcp_hdr_recv_prep(struct iscsi_tcp_conn *tcp_conn);
+extern int iscsi_tcp_recv_skb(struct iscsi_conn *conn, struct sk_buff *skb,
+			      unsigned int offset, bool offloaded, int *status);
+extern void iscsi_tcp_cleanup_task(struct iscsi_task *task);
+extern int iscsi_tcp_task_init(struct iscsi_task *task);
+extern int iscsi_tcp_task_xmit(struct iscsi_task *task);
+
+/* segment helpers */
+extern int iscsi_tcp_recv_segment_is_hdr(struct iscsi_tcp_conn *tcp_conn);
+extern int iscsi_tcp_segment_done(struct iscsi_segment *segment, int recv,
+				  unsigned copied);
+extern void iscsi_tcp_segment_unmap(struct iscsi_segment *segment);
+
+extern void iscsi_segment_init_linear(struct iscsi_segment *segment,
+				      void *data, size_t size,
+				      iscsi_segment_done_fn_t *done,
+				      struct hash_desc *hash);
+extern int
+iscsi_segment_seek_sg(struct iscsi_segment *segment,
+		      struct scatterlist *sg_list, unsigned int sg_count,
+		      unsigned int offset, size_t size,
+		      iscsi_segment_done_fn_t *done, struct hash_desc *hash);
+
+/* digest helpers */
+extern void iscsi_tcp_dgst_header(struct hash_desc *hash, const void *hdr,
+				  size_t hdrlen,
+				  unsigned char digest[ISCSI_DIGEST_SIZE]);
+extern struct iscsi_cls_conn *
+iscsi_tcp_conn_setup(struct iscsi_cls_session *cls_session, int dd_data_size,
+		     uint32_t conn_idx);
+extern void iscsi_tcp_conn_teardown(struct iscsi_cls_conn *cls_conn);
+
+/* misc helpers */
+extern int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session);
+extern void iscsi_tcp_r2tpool_free(struct iscsi_session *session);
+
+extern void iscsi_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
+				     struct iscsi_stats *stats);
+#endif /* LIBISCSI_TCP_H */