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Commit 9014db20 authored by Stefan Raspl's avatar Stefan Raspl Committed by David S. Miller
Browse files

smc: add support for splice() 



Provide an implementation for splice() when we are using SMC. See
smc_splice_read() for further details.

Signed-off-by: default avatarStefan Raspl <raspl@linux.ibm.com>
Signed-off-by: default avatarUrsula Braun <ubraun@linux.ibm.com&gt;&lt;>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2ef4f27a

net/smc/af_smc.c

+32 −6
Original line number Diff line number Diff line
@@ -1163,10 +1163,12 @@ static int smc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, 
		goto out;

	}



	if (smc->use_fallback)

	if (smc->use_fallback) {

		rc = smc->clcsock->ops->recvmsg(smc->clcsock, msg, len, flags);

	else

		rc = smc_rx_recvmsg(smc, msg, len, flags);

	} else {

		msg->msg_namelen = 0;

		rc = smc_rx_recvmsg(smc, msg, NULL, len, flags);

	}



out:

	release_sock(sk);
@@ -1447,6 +1449,12 @@ static ssize_t smc_sendpage(struct socket *sock, struct page *page, 
	return rc;

}



/* Map the affected portions of the rmbe into an spd, note the number of bytes

 * to splice in conn->splice_pending, and press 'go'. Delays consumer cursor

 * updates till whenever a respective page has been fully processed.

 * Note that subsequent recv() calls have to wait till all splice() processing

 * completed.

 */

static ssize_t smc_splice_read(struct socket *sock, loff_t *ppos,

			       struct pipe_inode_info *pipe, size_t len,

			       unsigned int flags)
@@ -1457,16 +1465,34 @@ static ssize_t smc_splice_read(struct socket *sock, loff_t *ppos, 


	smc = smc_sk(sk);

	lock_sock(sk);

	if ((sk->sk_state != SMC_ACTIVE) && (sk->sk_state != SMC_CLOSED))



	if (sk->sk_state == SMC_INIT ||

	    sk->sk_state == SMC_LISTEN ||

	    sk->sk_state == SMC_CLOSED)

		goto out;



	if (sk->sk_state == SMC_PEERFINCLOSEWAIT) {

		rc = 0;

		goto out;

	}



	if (smc->use_fallback) {

		rc = smc->clcsock->ops->splice_read(smc->clcsock, ppos,

						    pipe, len, flags);

	} else {

		rc = -EOPNOTSUPP;

		if (*ppos) {

			rc = -ESPIPE;

			goto out;

		}

		if (flags & SPLICE_F_NONBLOCK)

			flags = MSG_DONTWAIT;

		else

			flags = 0;

		rc = smc_rx_recvmsg(smc, NULL, pipe, len, flags);

	}

out:

	release_sock(sk);



	return rc;

}

net/smc/smc.h

+3 −0
Original line number Diff line number Diff line
@@ -164,6 +164,9 @@ struct smc_connection { 
	atomic_t		bytes_to_rcv;	/* arrived data,

						 * not yet received

						 */

	atomic_t		splice_pending;	/* number of spliced bytes

						 * pending processing

						 */

#ifndef KERNEL_HAS_ATOMIC64

	spinlock_t		acurs_lock;	/* protect cursors */

#endif

net/smc/smc_rx.c

+147 −16
Original line number Diff line number Diff line
@@ -43,6 +43,116 @@ static void smc_rx_wake_up(struct sock *sk) 
	rcu_read_unlock();

}



/* Update consumer cursor

 *   @conn   connection to update

 *   @cons   consumer cursor

 *   @len    number of Bytes consumed

 */

static void smc_rx_update_consumer(struct smc_connection *conn,

				   union smc_host_cursor cons, size_t len)

{

	smc_curs_add(conn->rmbe_size, &cons, len);

	smc_curs_write(&conn->local_tx_ctrl.cons, smc_curs_read(&cons, conn),

		       conn);

	/* send consumer cursor update if required */

	/* similar to advertising new TCP rcv_wnd if required */

	smc_tx_consumer_update(conn);

}



struct smc_spd_priv {

	struct smc_sock *smc;

	size_t		 len;

};



static void smc_rx_pipe_buf_release(struct pipe_inode_info *pipe,

				    struct pipe_buffer *buf)

{

	struct smc_spd_priv *priv = (struct smc_spd_priv *)buf->private;

	struct smc_sock *smc = priv->smc;

	struct smc_connection *conn;

	union smc_host_cursor cons;

	struct sock *sk = &smc->sk;



	if (sk->sk_state == SMC_CLOSED ||

	    sk->sk_state == SMC_PEERFINCLOSEWAIT ||

	    sk->sk_state == SMC_APPFINCLOSEWAIT)

		goto out;

	conn = &smc->conn;

	lock_sock(sk);

	smc_curs_write(&cons, smc_curs_read(&conn->local_tx_ctrl.cons, conn),

		       conn);

	smc_rx_update_consumer(conn, cons, priv->len);

	release_sock(sk);

	if (atomic_sub_and_test(priv->len, &conn->splice_pending))

		smc_rx_wake_up(sk);

out:

	kfree(priv);

	put_page(buf->page);

	sock_put(sk);

}



static int smc_rx_pipe_buf_nosteal(struct pipe_inode_info *pipe,

				   struct pipe_buffer *buf)

{

	return 1;

}



static const struct pipe_buf_operations smc_pipe_ops = {

	.can_merge = 0,

	.confirm = generic_pipe_buf_confirm,

	.release = smc_rx_pipe_buf_release,

	.steal = smc_rx_pipe_buf_nosteal,

	.get = generic_pipe_buf_get

};



static void smc_rx_spd_release(struct splice_pipe_desc *spd,

			       unsigned int i)

{

	put_page(spd->pages[i]);

}



static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,

			 struct smc_sock *smc)

{

	struct splice_pipe_desc spd;

	struct partial_page partial;

	struct smc_spd_priv *priv;

	struct page *page;

	int bytes;



	page = virt_to_page(smc->conn.rmb_desc->cpu_addr);

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);

	if (!priv)

		return -ENOMEM;

	priv->len = len;

	priv->smc = smc;

	partial.offset = src - (char *)smc->conn.rmb_desc->cpu_addr;

	partial.len = len;

	partial.private = (unsigned long)priv;



	spd.nr_pages_max = 1;

	spd.nr_pages = 1;

	spd.pages = &page;

	spd.partial = &partial;

	spd.ops = &smc_pipe_ops;

	spd.spd_release = smc_rx_spd_release;



	bytes = splice_to_pipe(pipe, &spd);

	if (bytes > 0) {

		sock_hold(&smc->sk);

		get_page(smc->conn.rmb_desc->pages);

		atomic_add(bytes, &smc->conn.splice_pending);

	}



	return bytes;

}



static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)

{

	return atomic_read(&conn->bytes_to_rcv) &&

	       !atomic_read(&conn->splice_pending);

}



/* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted

 *   @smc    smc socket

 *   @timeo  pointer to max seconds to wait, pointer to value 0 for no timeout
@@ -74,19 +184,25 @@ int smc_rx_wait(struct smc_sock *smc, long *timeo, 
	return rc;

}



/* rcvbuf consumer: main API called by socket layer.

 * called under sk lock.

/* smc_rx_recvmsg - receive data from RMBE

 * @msg:	copy data to receive buffer

 * @pipe:	copy data to pipe if set - indicates splice() call

 *

 * rcvbuf consumer: main API called by socket layer.

 * Called under sk lock.

 */

int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len,

		   int flags)

int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,

		   struct pipe_inode_info *pipe, size_t len, int flags)

{

	size_t copylen, read_done = 0, read_remaining = len;

	size_t chunk_len, chunk_off, chunk_len_sum;

	struct smc_connection *conn = &smc->conn;

	int (*func)(struct smc_connection *conn);

	union smc_host_cursor cons;

	int readable, chunk;

	char *rcvbuf_base;

	struct sock *sk;

	int splbytes;

	long timeo;

	int target;		/* Read at least these many bytes */

	int rc;
@@ -102,12 +218,11 @@ int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len, 
	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);

	target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);



	msg->msg_namelen = 0;

	/* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */

	rcvbuf_base = conn->rmb_desc->cpu_addr;



	do { /* while (read_remaining) */

		if (read_done >= target)

		if (read_done >= target || (pipe && read_done))

			break;



		if (atomic_read(&conn->bytes_to_rcv))
@@ -156,11 +271,24 @@ int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len, 
		/* initialize variables for 1st iteration of subsequent loop */

		/* could be just 1 byte, even after waiting on data above */

		readable = atomic_read(&conn->bytes_to_rcv);

		splbytes = atomic_read(&conn->splice_pending);

		if (!readable || (msg && splbytes)) {

			if (splbytes)

				func = smc_rx_data_available_and_no_splice_pend;

			else

				func = smc_rx_data_available;

			smc_rx_wait(smc, &timeo, func);

			continue;

		}



		/* not more than what user space asked for */

		copylen = min_t(size_t, read_remaining, readable);

		smc_curs_write(&cons,

			       smc_curs_read(&conn->local_tx_ctrl.cons, conn),

			       conn);

		/* subsequent splice() calls pick up where previous left */

		if (splbytes)

			smc_curs_add(conn->rmbe_size, &cons, splbytes);

		/* determine chunks where to read from rcvbuf */

		/* either unwrapped case, or 1st chunk of wrapped case */

		chunk_len = min_t(size_t,
@@ -170,9 +298,16 @@ int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len, 
		smc_rmb_sync_sg_for_cpu(conn);

		for (chunk = 0; chunk < 2; chunk++) {

			if (!(flags & MSG_TRUNC)) {

				rc = memcpy_to_msg(msg, rcvbuf_base + chunk_off,

				if (msg) {

					rc = memcpy_to_msg(msg, rcvbuf_base +

							   chunk_off,

							   chunk_len);

				if (rc) {

				} else {

					rc = smc_rx_splice(pipe, rcvbuf_base +

							chunk_off, chunk_len,

							smc);

				}

				if (rc < 0) {

					if (!read_done)

						read_done = -EFAULT;

					smc_rmb_sync_sg_for_device(conn);
@@ -193,18 +328,13 @@ int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len, 


		/* update cursors */

		if (!(flags & MSG_PEEK)) {

			smc_curs_add(conn->rmbe_size, &cons, copylen);

			/* increased in recv tasklet smc_cdc_msg_rcv() */

			smp_mb__before_atomic();

			atomic_sub(copylen, &conn->bytes_to_rcv);

			/* guarantee 0 <= bytes_to_rcv <= rmbe_size */

			smp_mb__after_atomic();

			smc_curs_write(&conn->local_tx_ctrl.cons,

				       smc_curs_read(&cons, conn),

				       conn);

			/* send consumer cursor update if required */

			/* similar to advertising new TCP rcv_wnd if required */

			smc_tx_consumer_update(conn);

			if (msg)

				smc_rx_update_consumer(conn, cons, copylen);

		}

	} while (read_remaining);

out:
@@ -215,4 +345,5 @@ int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len, 
void smc_rx_init(struct smc_sock *smc)

{

	smc->sk.sk_data_ready = smc_rx_wake_up;

	atomic_set(&smc->conn.splice_pending, 0);

}

net/smc/smc_rx.h

+3 −3
Original line number Diff line number Diff line
@@ -18,8 +18,9 @@ 
#include "smc.h"



void smc_rx_init(struct smc_sock *smc);

int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len,

		   int flags);



int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,

		   struct pipe_inode_info *pipe, size_t len, int flags);

int smc_rx_wait(struct smc_sock *smc, long *timeo,

		int (*fcrit)(struct smc_connection *conn));

static inline int smc_rx_data_available(struct smc_connection *conn)
@@ -27,5 +28,4 @@ static inline int smc_rx_data_available(struct smc_connection *conn) 
	return atomic_read(&conn->bytes_to_rcv);

}





#endif /* SMC_RX_H */