linux-stable/net/sunrpc/socklib.c
Al Viro de4eda9de2 use less confusing names for iov_iter direction initializers
READ/WRITE proved to be actively confusing - the meanings are
"data destination, as used with read(2)" and "data source, as
used with write(2)", but people keep interpreting those as
"we read data from it" and "we write data to it", i.e. exactly
the wrong way.

Call them ITER_DEST and ITER_SOURCE - at least that is harder
to misinterpret...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2022-11-25 13:01:55 -05:00

324 lines
7.8 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/net/sunrpc/socklib.c
*
* Common socket helper routines for RPC client and server
*
* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
*/
#include <linux/compiler.h>
#include <linux/netdevice.h>
#include <linux/gfp.h>
#include <linux/skbuff.h>
#include <linux/types.h>
#include <linux/pagemap.h>
#include <linux/udp.h>
#include <linux/sunrpc/msg_prot.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/xdr.h>
#include <linux/export.h>
#include "socklib.h"
/*
* Helper structure for copying from an sk_buff.
*/
struct xdr_skb_reader {
struct sk_buff *skb;
unsigned int offset;
size_t count;
__wsum csum;
};
typedef size_t (*xdr_skb_read_actor)(struct xdr_skb_reader *desc, void *to,
size_t len);
/**
* xdr_skb_read_bits - copy some data bits from skb to internal buffer
* @desc: sk_buff copy helper
* @to: copy destination
* @len: number of bytes to copy
*
* Possibly called several times to iterate over an sk_buff and copy
* data out of it.
*/
static size_t
xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
{
if (len > desc->count)
len = desc->count;
if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
return 0;
desc->count -= len;
desc->offset += len;
return len;
}
/**
* xdr_skb_read_and_csum_bits - copy and checksum from skb to buffer
* @desc: sk_buff copy helper
* @to: copy destination
* @len: number of bytes to copy
*
* Same as skb_read_bits, but calculate a checksum at the same time.
*/
static size_t xdr_skb_read_and_csum_bits(struct xdr_skb_reader *desc, void *to, size_t len)
{
unsigned int pos;
__wsum csum2;
if (len > desc->count)
len = desc->count;
pos = desc->offset;
csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len);
desc->csum = csum_block_add(desc->csum, csum2, pos);
desc->count -= len;
desc->offset += len;
return len;
}
/**
* xdr_partial_copy_from_skb - copy data out of an skb
* @xdr: target XDR buffer
* @base: starting offset
* @desc: sk_buff copy helper
* @copy_actor: virtual method for copying data
*
*/
static ssize_t
xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb_reader *desc, xdr_skb_read_actor copy_actor)
{
struct page **ppage = xdr->pages;
unsigned int len, pglen = xdr->page_len;
ssize_t copied = 0;
size_t ret;
len = xdr->head[0].iov_len;
if (base < len) {
len -= base;
ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
copied += ret;
if (ret != len || !desc->count)
goto out;
base = 0;
} else
base -= len;
if (unlikely(pglen == 0))
goto copy_tail;
if (unlikely(base >= pglen)) {
base -= pglen;
goto copy_tail;
}
if (base || xdr->page_base) {
pglen -= base;
base += xdr->page_base;
ppage += base >> PAGE_SHIFT;
base &= ~PAGE_MASK;
}
do {
char *kaddr;
/* ACL likes to be lazy in allocating pages - ACLs
* are small by default but can get huge. */
if ((xdr->flags & XDRBUF_SPARSE_PAGES) && *ppage == NULL) {
*ppage = alloc_page(GFP_NOWAIT | __GFP_NOWARN);
if (unlikely(*ppage == NULL)) {
if (copied == 0)
copied = -ENOMEM;
goto out;
}
}
len = PAGE_SIZE;
kaddr = kmap_atomic(*ppage);
if (base) {
len -= base;
if (pglen < len)
len = pglen;
ret = copy_actor(desc, kaddr + base, len);
base = 0;
} else {
if (pglen < len)
len = pglen;
ret = copy_actor(desc, kaddr, len);
}
flush_dcache_page(*ppage);
kunmap_atomic(kaddr);
copied += ret;
if (ret != len || !desc->count)
goto out;
ppage++;
} while ((pglen -= len) != 0);
copy_tail:
len = xdr->tail[0].iov_len;
if (base < len)
copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
out:
return copied;
}
/**
* csum_partial_copy_to_xdr - checksum and copy data
* @xdr: target XDR buffer
* @skb: source skb
*
* We have set things up such that we perform the checksum of the UDP
* packet in parallel with the copies into the RPC client iovec. -DaveM
*/
int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
{
struct xdr_skb_reader desc;
desc.skb = skb;
desc.offset = 0;
desc.count = skb->len - desc.offset;
if (skb_csum_unnecessary(skb))
goto no_checksum;
desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_and_csum_bits) < 0)
return -1;
if (desc.offset != skb->len) {
__wsum csum2;
csum2 = skb_checksum(skb, desc.offset, skb->len - desc.offset, 0);
desc.csum = csum_block_add(desc.csum, csum2, desc.offset);
}
if (desc.count)
return -1;
if (csum_fold(desc.csum))
return -1;
if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
!skb->csum_complete_sw)
netdev_rx_csum_fault(skb->dev, skb);
return 0;
no_checksum:
if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
return -1;
if (desc.count)
return -1;
return 0;
}
EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
static inline int xprt_sendmsg(struct socket *sock, struct msghdr *msg,
size_t seek)
{
if (seek)
iov_iter_advance(&msg->msg_iter, seek);
return sock_sendmsg(sock, msg);
}
static int xprt_send_kvec(struct socket *sock, struct msghdr *msg,
struct kvec *vec, size_t seek)
{
iov_iter_kvec(&msg->msg_iter, ITER_SOURCE, vec, 1, vec->iov_len);
return xprt_sendmsg(sock, msg, seek);
}
static int xprt_send_pagedata(struct socket *sock, struct msghdr *msg,
struct xdr_buf *xdr, size_t base)
{
iov_iter_bvec(&msg->msg_iter, ITER_SOURCE, xdr->bvec, xdr_buf_pagecount(xdr),
xdr->page_len + xdr->page_base);
return xprt_sendmsg(sock, msg, base + xdr->page_base);
}
/* Common case:
* - stream transport
* - sending from byte 0 of the message
* - the message is wholly contained in @xdr's head iovec
*/
static int xprt_send_rm_and_kvec(struct socket *sock, struct msghdr *msg,
rpc_fraghdr marker, struct kvec *vec,
size_t base)
{
struct kvec iov[2] = {
[0] = {
.iov_base = &marker,
.iov_len = sizeof(marker)
},
[1] = *vec,
};
size_t len = iov[0].iov_len + iov[1].iov_len;
iov_iter_kvec(&msg->msg_iter, ITER_SOURCE, iov, 2, len);
return xprt_sendmsg(sock, msg, base);
}
/**
* xprt_sock_sendmsg - write an xdr_buf directly to a socket
* @sock: open socket to send on
* @msg: socket message metadata
* @xdr: xdr_buf containing this request
* @base: starting position in the buffer
* @marker: stream record marker field
* @sent_p: return the total number of bytes successfully queued for sending
*
* Return values:
* On success, returns zero and fills in @sent_p.
* %-ENOTSOCK if @sock is not a struct socket.
*/
int xprt_sock_sendmsg(struct socket *sock, struct msghdr *msg,
struct xdr_buf *xdr, unsigned int base,
rpc_fraghdr marker, unsigned int *sent_p)
{
unsigned int rmsize = marker ? sizeof(marker) : 0;
unsigned int remainder = rmsize + xdr->len - base;
unsigned int want;
int err = 0;
*sent_p = 0;
if (unlikely(!sock))
return -ENOTSOCK;
msg->msg_flags |= MSG_MORE;
want = xdr->head[0].iov_len + rmsize;
if (base < want) {
unsigned int len = want - base;
remainder -= len;
if (remainder == 0)
msg->msg_flags &= ~MSG_MORE;
if (rmsize)
err = xprt_send_rm_and_kvec(sock, msg, marker,
&xdr->head[0], base);
else
err = xprt_send_kvec(sock, msg, &xdr->head[0], base);
if (remainder == 0 || err != len)
goto out;
*sent_p += err;
base = 0;
} else {
base -= want;
}
if (base < xdr->page_len) {
unsigned int len = xdr->page_len - base;
remainder -= len;
if (remainder == 0)
msg->msg_flags &= ~MSG_MORE;
err = xprt_send_pagedata(sock, msg, xdr, base);
if (remainder == 0 || err != len)
goto out;
*sent_p += err;
base = 0;
} else {
base -= xdr->page_len;
}
if (base >= xdr->tail[0].iov_len)
return 0;
msg->msg_flags &= ~MSG_MORE;
err = xprt_send_kvec(sock, msg, &xdr->tail[0], base);
out:
if (err > 0) {
*sent_p += err;
err = 0;
}
return err;
}