path: root/net/sunrpc/xprtrdma/xprt_rdma.h

/* SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause */
/*
 * Copyright (c) 2014-2017 Oracle.  All rights reserved.
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 * General Public License (GPL) Version 2, available from the file
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#ifndef _LINUX_SUNRPC_XPRT_RDMA_H
#define _LINUX_SUNRPC_XPRT_RDMA_H

#include <linux/wait.h> 		/* wait_queue_head_t, etc */
#include <linux/spinlock.h> 		/* spinlock_t, etc */
#include <linux/atomic.h>		/* atomic_t, etc */
#include <linux/kref.h>			/* struct kref */
#include <linux/workqueue.h>		/* struct work_struct */

#include <rdma/rdma_cm.h>		/* RDMA connection api */
#include <rdma/ib_verbs.h>		/* RDMA verbs api */

#include <linux/sunrpc/clnt.h> 		/* rpc_xprt */
#include <linux/sunrpc/rpc_rdma.h> 	/* RPC/RDMA protocol */
#include <linux/sunrpc/xprtrdma.h> 	/* xprt parameters */

#define RDMA_RESOLVE_TIMEOUT	(5000)	/* 5 seconds */
#define RDMA_CONNECT_RETRY_MAX	(2)	/* retries if no listener backlog */

#define RPCRDMA_BIND_TO		(60U * HZ)
#define RPCRDMA_INIT_REEST_TO	(5U * HZ)
#define RPCRDMA_MAX_REEST_TO	(30U * HZ)
#define RPCRDMA_IDLE_DISC_TO	(5U * 60 * HZ)

/*
 * Interface Adapter -- one per transport instance
 */
struct rpcrdma_ia {
	struct rdma_cm_id 	*ri_id;
	struct ib_pd		*ri_pd;
	int			ri_async_rc;
	unsigned int		ri_max_segs;
	unsigned int		ri_max_frwr_depth;
	unsigned int		ri_max_send_sges;
	bool			ri_implicit_roundup;
	enum ib_mr_type		ri_mrtype;
	unsigned long		ri_flags;
	struct completion	ri_done;
	struct completion	ri_remove_done;
};

enum {
	RPCRDMA_IAF_REMOVING = 0,
};

/*
 * RDMA Endpoint -- one per transport instance
 */

struct rpcrdma_ep {
	unsigned int		rep_send_count;
	unsigned int		rep_send_batch;
	unsigned int		rep_max_inline_send;
	unsigned int		rep_max_inline_recv;
	int			rep_connected;
	struct ib_qp_init_attr	rep_attr;
	wait_queue_head_t 	rep_connect_wait;
	struct rpcrdma_connect_private	rep_cm_private;
	struct rdma_conn_param	rep_remote_cma;
	unsigned int		rep_max_requests;	/* set by /proc */
	unsigned int		rep_inline_send;	/* negotiated */
	unsigned int		rep_inline_recv;	/* negotiated */
	int			rep_receive_count;
};

/* Pre-allocate extra Work Requests for handling backward receives
 * and sends. This is a fixed value because the Work Queues are
 * allocated when the forward channel is set up, long before the
 * backchannel is provisioned. This value is two times
 * NFS4_DEF_CB_SLOT_TABLE_SIZE.
 */
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
#define RPCRDMA_BACKWARD_WRS (32)
#else
#define RPCRDMA_BACKWARD_WRS (0)
#endif

/* Registered buffer -- registered kmalloc'd memory for RDMA SEND/RECV
 *
 * The below structure appears at the front of a large region of kmalloc'd
 * memory, which always starts on a good alignment boundary.
 */

struct rpcrdma_regbuf {
	struct ib_sge		rg_iov;
	struct ib_device	*rg_device;
	enum dma_data_direction	rg_direction;
	void			*rg_data;
};

static inline u64 rdmab_addr(struct rpcrdma_regbuf *rb)
{
	return rb->rg_iov.addr;
}

static inline u32 rdmab_length(struct rpcrdma_regbuf *rb)
{
	return rb->rg_iov.length;
}

static inline u32 rdmab_lkey(struct rpcrdma_regbuf *rb)
{
	return rb->rg_iov.lkey;
}

static inline struct ib_device *rdmab_device(struct rpcrdma_regbuf *rb)
{
	return rb->rg_device;
}

static inline void *rdmab_data(const struct rpcrdma_regbuf *rb)
{
	return rb->rg_data;
}

#define RPCRDMA_DEF_GFP		(GFP_NOIO | __GFP_NOWARN)

/* To ensure a transport can always make forward progress,
 * the number of RDMA segments allowed in header chunk lists
 * is capped at 8. This prevents less-capable devices and
 * memory registrations from overrunning the Send buffer
 * while building chunk lists.
 *
 * Elements of the Read list take up more room than the
 * Write list or Reply chunk. 8 read segments means the Read
 * list (or Write list or Reply chunk) cannot consume more
 * than
 *
 * ((8 + 2) * read segment size) + 1 XDR words, or 244 bytes.
 *
 * And the fixed part of the header is another 24 bytes.
 *
 * The smallest inline threshold is 1024 bytes, ensuring that
 * at least 750 bytes are available for RPC messages.
 */
enum {
	RPCRDMA_MAX_HDR_SEGS = 8,
	RPCRDMA_HDRBUF_SIZE = 256,
};

/*
 * struct rpcrdma_rep -- this structure encapsulates state required
 * to receive and complete an RPC Reply, asychronously. It needs
 * several pieces of state:
 *
 *   o receive buffer and ib_sge (donated to provider)
 *   o status of receive (success or not, length, inv rkey)
 *   o bookkeeping state to get run by reply handler (XDR stream)
 *
 * These structures are allocated during transport initialization.
 * N of these are associated with a transport instance, managed by
 * struct rpcrdma_buffer. N is the max number of outstanding RPCs.
 */

struct rpcrdma_rep {
	struct ib_cqe		rr_cqe;
	__be32			rr_xid;
	__be32			rr_vers;
	__be32			rr_proc;
	int			rr_wc_flags;
	u32			rr_inv_rkey;
	bool			rr_temp;
	struct rpcrdma_regbuf	*rr_rdmabuf;
	struct rpcrdma_xprt	*rr_rxprt;
	struct rpc_rqst		*rr_rqst;
	struct xdr_buf		rr_hdrbuf;
	struct xdr_stream	rr_stream;
	struct list_head	rr_list;
	struct ib_recv_wr	rr_recv_wr;
};

/* To reduce the rate at which a transport invokes ib_post_recv
 * (and thus the hardware doorbell rate), xprtrdma posts Receive
 * WRs in batches.
 *
 * Setting this to zero disables Receive post batching.
 */
enum {
	RPCRDMA_MAX_RECV_BATCH = 7,
};

/* struct rpcrdma_sendctx - DMA mapped SGEs to unmap after Send completes
 */
struct rpcrdma_req;
struct rpcrdma_xprt;
struct rpcrdma_sendctx {
	struct ib_send_wr	sc_wr;
	struct ib_cqe		sc_cqe;
	struct ib_device	*sc_device;
	struct rpcrdma_xprt	*sc_xprt;
	struct rpcrdma_req	*sc_req;
	unsigned int		sc_unmap_count;
	struct ib_sge		sc_sges[];
};

/*
 * struct rpcrdma_mr - external memory region metadata
 *
 * An external memory region is any buffer or page that is registered
 * on the fly (ie, not pre-registered).
 */
struct rpcrdma_req;
struct rpcrdma_frwr {
	struct ib_mr			*fr_mr;
	struct ib_cqe			fr_cqe;
	struct completion		fr_linv_done;
	struct rpcrdma_req		*fr_req;
	union {
		struct ib_reg_wr	fr_regwr;
		struct ib_send_wr	fr_invwr;
	};
};

struct rpcrdma_mr {
	struct list_head	mr_list;
	struct scatterlist	*mr_sg;
	int			mr_nents;
	enum dma_data_direction	mr_dir;
	struct rpcrdma_frwr	frwr;
	struct rpcrdma_xprt	*mr_xprt;
	u32			mr_handle;
	u32			mr_length;
	u64			mr_offset;
	struct work_struct	mr_recycle;
	struct list_head	mr_all;
};

/*
 * struct rpcrdma_req -- structure central to the request/reply sequence.
 *
 * N of these are associated with a transport instance, and stored in
 * struct rpcrdma_buffer. N is the max number of outstanding requests.
 *
 * It includes pre-registered buffer memory for send AND recv.
 * The recv buffer, however, is not owned by this structure, and
 * is "donated" to the hardware when a recv is posted. When a
 * reply is handled, the recv buffer used is given back to the
 * struct rpcrdma_req associated with the request.
 *
 * In addition to the basic memory, this structure includes an array
 * of iovs for send operations. The reason is that the iovs passed to
 * ib_post_{send,recv} must not be modified until the work request
 * completes.
 */

/* Maximum number of page-sized "segments" per chunk list to be
 * registered or invalidated. Must handle a Reply chunk:
 */
enum {
	RPCRDMA_MAX_IOV_SEGS	= 3,
	RPCRDMA_MAX_DATA_SEGS	= ((1 * 1024 * 1024) / PAGE_SIZE) + 1,
	RPCRDMA_MAX_SEGS	= RPCRDMA_MAX_DATA_SEGS +
				  RPCRDMA_MAX_IOV_SEGS,
};

struct rpcrdma_mr_seg {		/* chunk descriptors */
	u32		mr_len;		/* length of chunk or segment */
	struct page	*mr_page;	/* owning page, if any */
	char		*mr_offset;	/* kva if no page, else offset */
};

/* The Send SGE array is provisioned to send a maximum size
 * inline request:
 * - RPC-over-RDMA header
 * - xdr_buf head iovec
 * - RPCRDMA_MAX_INLINE bytes, in pages
 * - xdr_buf tail iovec
 *
 * The actual number of array elements consumed by each RPC
 * depends on the device's max_sge limit.
 */
enum {
	RPCRDMA_MIN_SEND_SGES = 3,
	RPCRDMA_MAX_PAGE_SGES = RPCRDMA_MAX_INLINE >> PAGE_SHIFT,
	RPCRDMA_MAX_SEND_SGES = 1 + 1 + RPCRDMA_MAX_PAGE_SGES + 1,
};

struct rpcrdma_buffer;
struct rpcrdma_req {
	struct list_head	rl_list;
	struct rpc_rqst		rl_slot;
	struct rpcrdma_rep	*rl_reply;
	struct xdr_stream	rl_stream;
	struct xdr_buf		rl_hdrbuf;
	struct rpcrdma_sendctx	*rl_sendctx;
	struct rpcrdma_regbuf	*rl_rdmabuf;	/* xprt header */
	struct rpcrdma_regbuf	*rl_sendbuf;	/* rq_snd_buf */
	struct rpcrdma_regbuf	*rl_recvbuf;	/* rq_rcv_buf */

	struct list_head	rl_all;
	struct kref		rl_kref;

	struct