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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: Stefan Raspl <raspl@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com><
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stefan Raspl 2018-05-03 18:12:39 +02:00 committed by David S. Miller
parent 2ef4f27ad0
commit 9014db202c
4 changed files with 185 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
net/smc/af_smc.c
View File

@ -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);
@ -1447,9 +1449,15 @@ out:
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)
unsigned int flags)
{
struct sock *sk = sock->sk;
struct smc_sock *smc;
@ -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;
}

3
net/smc/smc.h
View File

@ -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

163
net/smc/smc_rx.c
View File

@ -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 @@ copy:
/* 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 @@ copy:
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,
chunk_len);
if (rc) {
if (msg) {
rc = memcpy_to_msg(msg, rcvbuf_base +
chunk_off,
chunk_len);
} 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 @@ copy:
/* 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 @@ out:
void smc_rx_init(struct smc_sock *smc)
{
smc->sk.sk_data_ready = smc_rx_wake_up;
atomic_set(&smc->conn.splice_pending, 0);
}

6
net/smc/smc_rx.h
View File

@ -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 */