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ceph: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage() 

Use sendmsg() and MSG_SPLICE_PAGES rather than sendpage in ceph when
transmitting data.  For the moment, this can only transmit one page at a
time because of the architecture of net/ceph/, but if
write_partial_message_data() can be given a bvec[] at a time by the
iteration code, this would allow pages to be sent in a batch.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: Xiubo Li <xiubli@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Link: https://lore.kernel.org/r/20230623225513.2732256-5-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
David Howells 2023-06-23 23:55:01 +01:00 committed by Jakub Kicinski
parent 40a8c17aa7
commit fa094ccae1
1 changed files with 19 additions and 72 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

91
net/ceph/messenger_v2.c
View File

@ -117,91 +117,38 @@ static int ceph_tcp_recv(struct ceph_connection *con)
return ret;
}
static int do_sendmsg(struct socket *sock, struct iov_iter *it)
{
struct msghdr msg = { .msg_flags = CEPH_MSG_FLAGS };
int ret;
msg.msg_iter = *it;
while (iov_iter_count(it)) {
ret = sock_sendmsg(sock, &msg);
if (ret <= 0) {
if (ret == -EAGAIN)
ret = 0;
return ret;
}
iov_iter_advance(it, ret);
}
WARN_ON(msg_data_left(&msg));
return 1;
}
static int do_try_sendpage(struct socket *sock, struct iov_iter *it)
{
struct msghdr msg = { .msg_flags = CEPH_MSG_FLAGS };
struct bio_vec bv;
int ret;
if (WARN_ON(!iov_iter_is_bvec(it)))
return -EINVAL;
while (iov_iter_count(it)) {
/* iov_iter_iovec() for ITER_BVEC */
bvec_set_page(&bv, it->bvec->bv_page,
min(iov_iter_count(it),
it->bvec->bv_len - it->iov_offset),
it->bvec->bv_offset + it->iov_offset);
/*
* sendpage cannot properly handle pages with
* page_count == 0, we need to fall back to sendmsg if
* that's the case.
*
* Same goes for slab pages: skb_can_coalesce() allows
* coalescing neighboring slab objects into a single frag
* which triggers one of hardened usercopy checks.
*/
if (sendpage_ok(bv.bv_page)) {
ret = sock->ops->sendpage(sock, bv.bv_page,
bv.bv_offset, bv.bv_len,
CEPH_MSG_FLAGS);
} else {
iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bv, 1, bv.bv_len);
ret = sock_sendmsg(sock, &msg);
}
if (ret <= 0) {
if (ret == -EAGAIN)
ret = 0;
return ret;
}
iov_iter_advance(it, ret);
}
return 1;
}
/*
* Write as much as possible. The socket is expected to be corked,
* so we don't bother with MSG_MORE/MSG_SENDPAGE_NOTLAST here.
* so we don't bother with MSG_MORE here.
*
* Return:
* 1 - done, nothing (else) to write
* >0 - done, nothing (else) to write
* 0 - socket is full, need to wait
* <0 - error
*/
static int ceph_tcp_send(struct ceph_connection *con)
{
struct msghdr msg = {
.msg_iter = con->v2.out_iter,
.msg_flags = CEPH_MSG_FLAGS,
};
int ret;
if (WARN_ON(!iov_iter_is_bvec(&con->v2.out_iter)))
return -EINVAL;
if (con->v2.out_iter_sendpage)
msg.msg_flags |= MSG_SPLICE_PAGES;
dout("%s con %p have %zu try_sendpage %d\n", __func__, con,
iov_iter_count(&con->v2.out_iter), con->v2.out_iter_sendpage);
if (con->v2.out_iter_sendpage)
ret = do_try_sendpage(con->sock, &con->v2.out_iter);
else
ret = do_sendmsg(con->sock, &con->v2.out_iter);
ret = sock_sendmsg(con->sock, &msg);
if (ret > 0)
iov_iter_advance(&con->v2.out_iter, ret);
else if (ret == -EAGAIN)
ret = 0;
dout("%s con %p ret %d left %zu\n", __func__, con, ret,
iov_iter_count(&con->v2.out_iter));
return ret;