Here's the first tranche of patches towards providing a MSG_SPLICE_PAGES
internal sendmsg flag that is intended to replace the ->sendpage() op with
calls to sendmsg(). MSG_SPLICE_PAGES is a hint that tells the protocol
that it should splice the pages supplied if it can and copy them if not.
This will allow splice to pass multiple pages in a single call and allow
certain parts of higher protocols (e.g. sunrpc, iwarp) to pass an entire
message in one go rather than having to send them piecemeal. This should
also make it easier to handle the splicing of multipage folios.
A helper, skb_splice_from_iter() is provided to do the work of splicing or
copying data from an iterator. If a page is determined to be unspliceable
(such as being in the slab), then the helper will give an error.
Note that this facility is not made available to userspace and does not
provide any sort of callback.
This set consists of the following parts:
(1) Define the MSG_SPLICE_PAGES flag and prevent sys_sendmsg() from being
able to set it.
(2) Add an extra argument to skb_append_pagefrags() so that something
other than MAX_SKB_FRAGS can be used (sysctl_max_skb_frags for
example).
(3) Add the skb_splice_from_iter() helper to handle splicing pages into
skbuffs for MSG_SPLICE_PAGES that can be shared by TCP, IP/UDP and
AF_UNIX.
(4) Implement MSG_SPLICE_PAGES support in TCP.
(5) Make do_tcp_sendpages() just wrap sendmsg() and then fold it in to its
various callers.
(6) Implement MSG_SPLICE_PAGES support in IP and make udp_sendpage() just
a wrapper around sendmsg().
(7) Implement MSG_SPLICE_PAGES support in IP6/UDP6.
(8) Implement MSG_SPLICE_PAGES support in AF_UNIX.
(9) Make AF_UNIX copy unspliceable pages.
I've pushed the patches here also:
https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=sendpage-1
The follow-on patches are on branch iov-sendpage on the same tree.
David
Changes
=======
ver #8)
- Order local variables in reverse xmas tree order.
- Remove duplicate coalescence check.
- Warn if sendpage_ok() fails.
ver #7)
- Rebase after merge window.
- In ____sys_sendmsg(), clear internal flags before setting msg_flags.
- Clear internal flags in uring io_send{,_zc}().
- Export skb_splice_from_iter().
- Missed changing a "zc = 1" in tcp_sendmsg_locked().
- Remove now-unused csum_page() from UDP.
- Add a patch to make AF_UNIX sendpage() just a wrapper around sendmsg().
- Return an error if !sendpage_ok() rather than copying for now.
- Drop the page frag allocator patches for the moment.
ver #6)
- Removed a couple of leftover page pointer declarations.
- In TCP, set zc to 0/MSG_ZEROCOPY/MSG_SPLICE_PAGES rather than 0/1/2.
- Add a max-frags argument to skb_append_pagefrags().
- Extract the AF_UNIX helper out into a common helper and use it for
IP/UDP and TCP too.
- udp_sendpage() shouldn't lock the socket around udp_sendmsg().
- udp_sendpage() should only set MSG_MORE if MSG_SENDPAGE_NOTLAST is set.
- In siw, don't clear MSG_SPLICE_PAGES on the last page.
ver #5)
- Dropped the samples patch as it causes lots of failures in the patchwork
32-bit builds due to apparent libc userspace header issues.
- Made the pagefrag alloc patches alter the Google gve driver too.
- Rearranged the patches to put the support in IP before altering UDP.
ver #4)
- Added some sample socket-I/O programs into samples/net/.
- Fix a missing page-get in AF_KCM.
- Init the sgtable and mark the end in AF_ALG when calling
netfs_extract_iter_to_sg().
- Add a destructor func for page frag caches prior to generalising it and
making it per-cpu.
ver #3)
- Dropped the iterator-of-iterators patch.
- Only expunge MSG_SPLICE_PAGES in sys_send[m]msg, not sys_recv[m]msg.
- Split MSG_SPLICE_PAGES code in __ip_append_data() out into helper
functions.
- Implement MSG_SPLICE_PAGES support in __ip6_append_data() using the
above helper functions.
- Rename 'xlength' to 'initial_length'.
- Minimise the changes to sunrpc for the moment.
- Don't give -EOPNOTSUPP if NETIF_F_SG not available, just copy instead.
- Implemented MSG_SPLICE_PAGES support in the TLS, Chelsio-TLS and AF_KCM
code.
ver #2)
- Overhauled the page_frag_alloc() allocator: large folios and per-cpu.
- Got rid of my own zerocopy allocator.
- Use iov_iter_extract_pages() rather poking in iter->bvec.
- Made page splicing fall back to page copying on a page-by-page basis.
- Made splice_to_socket() pass 16 pipe buffers at a time.
- Made AF_ALG/hash use finup/digest where possible in sendmsg.
- Added an iterator-of-iterators, ITER_ITERLIST.
- Made sunrpc use the iterator-of-iterators.
- Converted more drivers.
Link: https://lore.kernel.org/r/[email protected]/ # v1
Link: https://lore.kernel.org/r/[email protected]/ # v2
Link: https://lore.kernel.org/r/[email protected]/ # v3
Link: https://lore.kernel.org/r/[email protected]/ # v4
Link: https://lore.kernel.org/r/[email protected]/ # v5
Link: https://lore.kernel.org/r/[email protected]/ # v6
Link: https://lore.kernel.org/r/[email protected]/ # v7
David Howells (16):
net: Declare MSG_SPLICE_PAGES internal sendmsg() flag
net: Pass max frags into skb_append_pagefrags()
net: Add a function to splice pages into an skbuff for
MSG_SPLICE_PAGES
tcp: Support MSG_SPLICE_PAGES
tcp: Convert do_tcp_sendpages() to use MSG_SPLICE_PAGES
tcp_bpf: Inline do_tcp_sendpages as it's now a wrapper around
tcp_sendmsg
espintcp: Inline do_tcp_sendpages()
tls: Inline do_tcp_sendpages()
siw: Inline do_tcp_sendpages()
tcp: Fold do_tcp_sendpages() into tcp_sendpage_locked()
ip, udp: Support MSG_SPLICE_PAGES
ip6, udp6: Support MSG_SPLICE_PAGES
udp: Convert udp_sendpage() to use MSG_SPLICE_PAGES
ip: Remove ip_append_page()
af_unix: Support MSG_SPLICE_PAGES
unix: Convert udp_sendpage() to use MSG_SPLICE_PAGES
drivers/infiniband/sw/siw/siw_qp_tx.c | 17 +-
include/linux/skbuff.h | 5 +-
include/linux/socket.h | 3 +
include/net/ip.h | 2 -
include/net/tcp.h | 2 -
include/net/tls.h | 2 +-
io_uring/net.c | 2 +
net/core/skbuff.c | 92 ++++++++++-
net/ipv4/ip_output.c | 164 +++-----------------
net/ipv4/tcp.c | 214 ++++++--------------------
net/ipv4/tcp_bpf.c | 20 ++-
net/ipv4/udp.c | 51 +-----
net/ipv6/ip6_output.c | 17 ++
net/socket.c | 2 +
net/tls/tls_main.c | 24 +--
net/unix/af_unix.c | 183 +++++-----------------
net/xfrm/espintcp.c | 10 +-
17 files changed, 278 insertions(+), 532 deletions(-)
Declare MSG_SPLICE_PAGES, an internal sendmsg() flag, that hints to a
network protocol that it should splice pages from the source iterator
rather than copying the data if it can. This flag is added to a list that
is cleared by sendmsg syscalls on entry.
This is intended as a replacement for the ->sendpage() op, allowing a way
to splice in several multipage folios in one go.
Signed-off-by: David Howells <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
cc: "David S. Miller" <[email protected]>
cc: Eric Dumazet <[email protected]>
cc: Jakub Kicinski <[email protected]>
cc: Paolo Abeni <[email protected]>
cc: Jens Axboe <[email protected]>
cc: Matthew Wilcox <[email protected]>
cc: [email protected]
cc: [email protected]
---
Notes:
ver #7)
- In ____sys_sendmsg(), clear internal flags before setting msg_flags.
- Clear internal flags in uring io_send{,_zc}().
include/linux/socket.h | 3 +++
io_uring/net.c | 2 ++
net/socket.c | 2 ++
3 files changed, 7 insertions(+)
diff --git a/include/linux/socket.h b/include/linux/socket.h
index 13c3a237b9c9..bd1cc3238851 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -327,6 +327,7 @@ struct ucred {
*/
#define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */
+#define MSG_SPLICE_PAGES 0x8000000 /* Splice the pages from the iterator in sendmsg() */
#define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */
#define MSG_CMSG_CLOEXEC 0x40000000 /* Set close_on_exec for file
descriptor received through
@@ -337,6 +338,8 @@ struct ucred {
#define MSG_CMSG_COMPAT 0 /* We never have 32 bit fixups */
#endif
+/* Flags to be cleared on entry by sendmsg and sendmmsg syscalls */
+#define MSG_INTERNAL_SENDMSG_FLAGS (MSG_SPLICE_PAGES)
/* Setsockoptions(2) level. Thanks to BSD these must match IPPROTO_xxx */
#define SOL_IP 0
diff --git a/io_uring/net.c b/io_uring/net.c
index 89e839013837..f7cbb3c7a575 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -389,6 +389,7 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
if (flags & MSG_WAITALL)
min_ret = iov_iter_count(&msg.msg_iter);
+ flags &= ~MSG_INTERNAL_SENDMSG_FLAGS;
msg.msg_flags = flags;
ret = sock_sendmsg(sock, &msg);
if (ret < min_ret) {
@@ -1136,6 +1137,7 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
msg_flags |= MSG_DONTWAIT;
if (msg_flags & MSG_WAITALL)
min_ret = iov_iter_count(&msg.msg_iter);
+ msg_flags &= ~MSG_INTERNAL_SENDMSG_FLAGS;
msg.msg_flags = msg_flags;
msg.msg_ubuf = &io_notif_to_data(zc->notif)->uarg;
diff --git a/net/socket.c b/net/socket.c
index b7e01d0fe082..3df96e9ba4e2 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2138,6 +2138,7 @@ int __sys_sendto(int fd, void __user *buff, size_t len, unsigned int flags,
msg.msg_name = (struct sockaddr *)&address;
msg.msg_namelen = addr_len;
}
+ flags &= ~MSG_INTERNAL_SENDMSG_FLAGS;
if (sock->file->f_flags & O_NONBLOCK)
flags |= MSG_DONTWAIT;
msg.msg_flags = flags;
@@ -2483,6 +2484,7 @@ static int ____sys_sendmsg(struct socket *sock, struct msghdr *msg_sys,
msg_sys->msg_control = ctl_buf;
msg_sys->msg_control_is_user = false;
}
+ flags &= ~MSG_INTERNAL_SENDMSG_FLAGS;
msg_sys->msg_flags = flags;
if (sock->file->f_flags & O_NONBLOCK)
Pass the maximum number of fragments into skb_append_pagefrags() rather
than using MAX_SKB_FRAGS so that it can be used from code that wants to
specify sysctl_max_skb_frags.
Signed-off-by: David Howells <[email protected]>
cc: Eric Dumazet <[email protected]>
cc: "David S. Miller" <[email protected]>
cc: David Ahern <[email protected]>
cc: Jakub Kicinski <[email protected]>
cc: Paolo Abeni <[email protected]>
cc: Jens Axboe <[email protected]>
cc: Matthew Wilcox <[email protected]>
cc: [email protected]
---
include/linux/skbuff.h | 2 +-
net/core/skbuff.c | 4 ++--
net/ipv4/ip_output.c | 3 ++-
net/unix/af_unix.c | 2 +-
4 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 00e8c435fa1a..4c0ad48e38ca 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1383,7 +1383,7 @@ static inline int skb_pad(struct sk_buff *skb, int pad)
#define dev_kfree_skb(a) consume_skb(a)
int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
- int offset, size_t size);
+ int offset, size_t size, size_t max_frags);
struct skb_seq_state {
__u32 lower_offset;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 6724a84ebb09..7f53dcb26ad3 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -4188,13 +4188,13 @@ unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
EXPORT_SYMBOL(skb_find_text);
int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
- int offset, size_t size)
+ int offset, size_t size, size_t max_frags)
{
int i = skb_shinfo(skb)->nr_frags;
if (skb_can_coalesce(skb, i, page, offset)) {
skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
- } else if (i < MAX_SKB_FRAGS) {
+ } else if (i < max_frags) {
skb_zcopy_downgrade_managed(skb);
get_page(page);
skb_fill_page_desc_noacc(skb, i, page, offset, size);
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 61892268e8a6..52fc840898d8 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1450,7 +1450,8 @@ ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
if (len > size)
len = size;
- if (skb_append_pagefrags(skb, page, offset, len)) {
+ if (skb_append_pagefrags(skb, page, offset, len,
+ MAX_SKB_FRAGS)) {
err = -EMSGSIZE;
goto error;
}
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index cc695c9f09ec..dd55506b4632 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2349,7 +2349,7 @@ static ssize_t unix_stream_sendpage(struct socket *socket, struct page *page,
newskb = NULL;
}
- if (skb_append_pagefrags(skb, page, offset, size)) {
+ if (skb_append_pagefrags(skb, page, offset, size, MAX_SKB_FRAGS)) {
tail = skb;
goto alloc_skb;
}
do_tcp_sendpages() is now just a small wrapper around tcp_sendmsg_locked(),
so inline it. This is part of replacing ->sendpage() with a call to
sendmsg() with MSG_SPLICE_PAGES set.
Signed-off-by: David Howells <[email protected]>
cc: John Fastabend <[email protected]>
cc: Jakub Sitnicki <[email protected]>
cc: "David S. Miller" <[email protected]>
cc: Eric Dumazet <[email protected]>
cc: David Ahern <[email protected]>
cc: Jakub Kicinski <[email protected]>
cc: Paolo Abeni <[email protected]>
cc: Jens Axboe <[email protected]>
cc: Matthew Wilcox <[email protected]>
cc: [email protected]
cc: [email protected]
---
net/ipv4/tcp_bpf.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 2e9547467edb..0291d15acd19 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -72,11 +72,13 @@ static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes,
{
bool apply = apply_bytes;
struct scatterlist *sge;
+ struct msghdr msghdr = { .msg_flags = flags | MSG_SPLICE_PAGES, };
struct page *page;
int size, ret = 0;
u32 off;
while (1) {
+ struct bio_vec bvec;
bool has_tx_ulp;
sge = sk_msg_elem(msg, msg->sg.start);
@@ -88,16 +90,18 @@ static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes,
tcp_rate_check_app_limited(sk);
retry:
has_tx_ulp = tls_sw_has_ctx_tx(sk);
- if (has_tx_ulp) {
- flags |= MSG_SENDPAGE_NOPOLICY;
- ret = kernel_sendpage_locked(sk,
- page, off, size, flags);
- } else {
- ret = do_tcp_sendpages(sk, page, off, size, flags);
- }
+ if (has_tx_ulp)
+ msghdr.msg_flags |= MSG_SENDPAGE_NOPOLICY;
+ if (flags & MSG_SENDPAGE_NOTLAST)
+ msghdr.msg_flags |= MSG_MORE;
+
+ bvec_set_page(&bvec, page, size, off);
+ iov_iter_bvec(&msghdr.msg_iter, ITER_SOURCE, &bvec, 1, size);
+ ret = tcp_sendmsg_locked(sk, &msghdr, size);
if (ret <= 0)
return ret;
+
if (apply)
apply_bytes -= ret;
msg->sg.size -= ret;
@@ -404,7 +408,7 @@ static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
long timeo;
int flags;
- /* Don't let internal do_tcp_sendpages() flags through */
+ /* Don't let internal sendpage flags through */
flags = (msg->msg_flags & ~MSG_SENDPAGE_DECRYPTED);
flags |= MSG_NO_SHARED_FRAGS;
Make TCP's sendmsg() support MSG_SPLICE_PAGES. This causes pages to be
spliced or copied (if it cannot be spliced) from the source iterator.
This allows ->sendpage() to be replaced by something that can handle
multiple multipage folios in a single transaction.
Signed-off-by: David Howells <[email protected]>
cc: Eric Dumazet <[email protected]>
cc: "David S. Miller" <[email protected]>
cc: David Ahern <[email protected]>
cc: Jakub Kicinski <[email protected]>
cc: Paolo Abeni <[email protected]>
cc: Jens Axboe <[email protected]>
cc: Matthew Wilcox <[email protected]>
cc: [email protected]
---
Notes:
ver #7)
- Missed a "zc = 1" in tcp_sendmsg_locked().
ver #6)
- Set zc to 0/MSG_ZEROCOPY/MSG_SPLICE_PAGES rather than 0/1/2.
- Use common helper.
net/ipv4/tcp.c | 43 ++++++++++++++++++++++++++++++++++++-------
1 file changed, 36 insertions(+), 7 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4d6392c16b7a..026f483f42e3 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1223,7 +1223,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
int flags, err, copied = 0;
int mss_now = 0, size_goal, copied_syn = 0;
int process_backlog = 0;
- bool zc = false;
+ int zc = 0;
long timeo;
flags = msg->msg_flags;
@@ -1234,17 +1234,22 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
if (msg->msg_ubuf) {
uarg = msg->msg_ubuf;
net_zcopy_get(uarg);
- zc = sk->sk_route_caps & NETIF_F_SG;
+ if (sk->sk_route_caps & NETIF_F_SG)
+ zc = MSG_ZEROCOPY;
} else if (sock_flag(sk, SOCK_ZEROCOPY)) {
uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb));
if (!uarg) {
err = -ENOBUFS;
goto out_err;
}
- zc = sk->sk_route_caps & NETIF_F_SG;
- if (!zc)
+ if (sk->sk_route_caps & NETIF_F_SG)
+ zc = MSG_ZEROCOPY;
+ else
uarg_to_msgzc(uarg)->zerocopy = 0;
}
+ } else if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES) && size) {
+ if (sk->sk_route_caps & NETIF_F_SG)
+ zc = MSG_SPLICE_PAGES;
}
if (unlikely(flags & MSG_FASTOPEN || inet_sk(sk)->defer_connect) &&
@@ -1307,7 +1312,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
goto do_error;
while (msg_data_left(msg)) {
- int copy = 0;
+ ssize_t copy = 0;
skb = tcp_write_queue_tail(sk);
if (skb)
@@ -1348,7 +1353,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
if (copy > msg_data_left(msg))
copy = msg_data_left(msg);
- if (!zc) {
+ if (zc == 0) {
bool merge = true;
int i = skb_shinfo(skb)->nr_frags;
struct page_frag *pfrag = sk_page_frag(sk);
@@ -1393,7 +1398,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
page_ref_inc(pfrag->page);
}
pfrag->offset += copy;
- } else {
+ } else if (zc == MSG_ZEROCOPY) {
/* First append to a fragless skb builds initial
* pure zerocopy skb
*/
@@ -1414,6 +1419,30 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
if (err < 0)
goto do_error;
copy = err;
+ } else if (zc == MSG_SPLICE_PAGES) {
+ /* Splice in data if we can; copy if we can't. */
+ if (tcp_downgrade_zcopy_pure(sk, skb))
+ goto wait_for_space;
+ copy = tcp_wmem_schedule(sk, copy);
+ if (!copy)
+ goto wait_for_space;
+
+ err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
+ sk->sk_allocation);
+ if (err < 0) {
+ if (err == -EMSGSIZE) {
+ tcp_mark_push(tp, skb);
+ goto new_segment;
+ }
+ goto do_error;
+ }
+ copy = err;
+
+ if (!(flags & MSG_NO_SHARED_FRAGS))
+ skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
+
+ sk_wmem_queued_add(sk, copy);
+ sk_mem_charge(sk, copy);
}
if (!copied)
do_tcp_sendpages() is now just a small wrapper around tcp_sendmsg_locked(),
so inline it, allowing do_tcp_sendpages() to be removed. This is part of
replacing ->sendpage() with a call to sendmsg() with MSG_SPLICE_PAGES set.
Signed-off-by: David Howells <[email protected]>
cc: Steffen Klassert <[email protected]>
cc: Herbert Xu <[email protected]>
cc: Eric Dumazet <[email protected]>
cc: "David S. Miller" <[email protected]>
cc: David Ahern <[email protected]>
cc: Jakub Kicinski <[email protected]>
cc: Paolo Abeni <[email protected]>
cc: Jens Axboe <[email protected]>
cc: Matthew Wilcox <[email protected]>
cc: [email protected]
---
net/xfrm/espintcp.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/net/xfrm/espintcp.c b/net/xfrm/espintcp.c
index 872b80188e83..3504925babdb 100644
--- a/net/xfrm/espintcp.c
+++ b/net/xfrm/espintcp.c
@@ -205,14 +205,16 @@ static int espintcp_sendskb_locked(struct sock *sk, struct espintcp_msg *emsg,
static int espintcp_sendskmsg_locked(struct sock *sk,
struct espintcp_msg *emsg, int flags)
{
+ struct msghdr msghdr = { .msg_flags = flags | MSG_SPLICE_PAGES, };
struct sk_msg *skmsg = &emsg->skmsg;
struct scatterlist *sg;
int done = 0;
int ret;
- flags |= MSG_SENDPAGE_NOTLAST;
+ msghdr.msg_flags |= MSG_SENDPAGE_NOTLAST;
sg = &skmsg->sg.data[skmsg->sg.start];
do {
+ struct bio_vec bvec;
size_t size = sg->length - emsg->offset;
int offset = sg->offset + emsg->offset;
struct page *p;
@@ -220,11 +222,13 @@ static int espintcp_sendskmsg_locked(struct sock *sk,
emsg->offset = 0;
if (sg_is_last(sg))
- flags &= ~MSG_SENDPAGE_NOTLAST;
+ msghdr.msg_flags &= ~MSG_SENDPAGE_NOTLAST;
p = sg_page(sg);
retry:
- ret = do_tcp_sendpages(sk, p, offset, size, flags);
+ bvec_set_page(&bvec, p, size, offset);
+ iov_iter_bvec(&msghdr.msg_iter, ITER_SOURCE, &bvec, 1, size);
+ ret = tcp_sendmsg_locked(sk, &msghdr, size);
if (ret < 0) {
emsg->offset = offset - sg->offset;
skmsg->sg.start += done;
Add a function to handle MSG_SPLICE_PAGES being passed internally to
sendmsg(). Pages are spliced into the given socket buffer if possible and
copied in if not (e.g. they're slab pages or have a zero refcount).
Signed-off-by: David Howells <[email protected]>
cc: Eric Dumazet <[email protected]>
cc: "David S. Miller" <[email protected]>
cc: David Ahern <[email protected]>
cc: Jakub Kicinski <[email protected]>
cc: Paolo Abeni <[email protected]>
cc: Al Viro <[email protected]>
cc: Jens Axboe <[email protected]>
cc: Matthew Wilcox <[email protected]>
cc: [email protected]
---
Notes:
ver #8)
- Order local variables in reverse xmas tree order.
- Remove duplicate coalescence check.
- Warn if sendpage_ok() fails.
ver #7)
- Export function.
- Never copy data, return -EIO if sendpage_ok() returns false.
include/linux/skbuff.h | 3 ++
net/core/skbuff.c | 88 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 91 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4c0ad48e38ca..1c5f0ac6f8c3 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -5097,5 +5097,8 @@ static inline void skb_mark_for_recycle(struct sk_buff *skb)
#endif
}
+ssize_t skb_splice_from_iter(struct sk_buff *skb, struct iov_iter *iter,
+ ssize_t maxsize, gfp_t gfp);
+
#endif /* __KERNEL__ */
#endif /* _LINUX_SKBUFF_H */
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 7f53dcb26ad3..f4a5b51aed22 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -6892,3 +6892,91 @@ nodefer: __kfree_skb(skb);
if (unlikely(kick) && !cmpxchg(&sd->defer_ipi_scheduled, 0, 1))
smp_call_function_single_async(cpu, &sd->defer_csd);
}
+
+static void skb_splice_csum_page(struct sk_buff *skb, struct page *page,
+ size_t offset, size_t len)
+{
+ const char *kaddr;
+ __wsum csum;
+
+ kaddr = kmap_local_page(page);
+ csum = csum_partial(kaddr + offset, len, 0);
+ kunmap_local(kaddr);
+ skb->csum = csum_block_add(skb->csum, csum, skb->len);
+}
+
+/**
+ * skb_splice_from_iter - Splice (or copy) pages to skbuff
+ * @skb: The buffer to add pages to
+ * @iter: Iterator representing the pages to be added
+ * @maxsize: Maximum amount of pages to be added
+ * @gfp: Allocation flags
+ *
+ * This is a common helper function for supporting MSG_SPLICE_PAGES. It
+ * extracts pages from an iterator and adds them to the socket buffer if
+ * possible, copying them to fragments if not possible (such as if they're slab
+ * pages).
+ *
+ * Returns the amount of data spliced/copied or -EMSGSIZE if there's
+ * insufficient space in the buffer to transfer anything.
+ */
+ssize_t skb_splice_from_iter(struct sk_buff *skb, struct iov_iter *iter,
+ ssize_t maxsize, gfp_t gfp)
+{
+ size_t frag_limit = READ_ONCE(sysctl_max_skb_frags);
+ struct page *pages[8], **ppages = pages;
+ ssize_t spliced = 0, ret = 0;
+ unsigned int i;
+
+ while (iter->count > 0) {
+ ssize_t space, nr;
+ size_t off, len;
+
+ ret = -EMSGSIZE;
+ space = frag_limit - skb_shinfo(skb)->nr_frags;
+ if (space < 0)
+ break;
+
+ /* We might be able to coalesce without increasing nr_frags */
+ nr = clamp_t(size_t, space, 1, ARRAY_SIZE(pages));
+
+ len = iov_iter_extract_pages(iter, &ppages, maxsize, nr, 0, &off);
+ if (len <= 0) {
+ ret = len ?: -EIO;
+ break;
+ }
+
+ i = 0;
+ do {
+ struct page *page = pages[i++];
+ size_t part = min_t(size_t, PAGE_SIZE - off, len);
+
+ ret = -EIO;
+ if (WARN_ON_ONCE(!sendpage_ok(page)))
+ goto out;
+
+ ret = skb_append_pagefrags(skb, page, off, part,
+ frag_limit);
+ if (ret < 0) {
+ iov_iter_revert(iter, len);
+ goto out;
+ }
+
+ if (skb->ip_summed == CHECKSUM_NONE)
+ skb_splice_csum_page(skb, page, off, part);
+
+ off = 0;
+ spliced += part;
+ maxsize -= part;
+ len -= part;
+ } while (len > 0);
+
+ if (maxsize <= 0)
+ break;
+ }
+
+out:
+ skb_len_add(skb, spliced);
+ return spliced ?: ret;
+}
+EXPORT_SYMBOL(skb_splice_from_iter);
There was a conflict with upstream net-next, so I've posted a new version that
fixes that.
David