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libceph: Partially revert changes to support MSG_SPLICE_PAGES

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Fix the mishandling of MSG_DONTWAIT and also reinstates the per-page
checking of the source pages (which might have come from a DIO write by
userspace) by partially reverting the changes to support MSG_SPLICE_PAGES
and doing things a little differently.  In messenger_v1:

 (1) The ceph_tcp_sendpage() is resurrected and the callers reverted to use
     that.

 (2) The callers now pass MSG_MORE unconditionally.  Previously, they were
     passing in MSG_MORE|MSG_SENDPAGE_NOTLAST and then degrading that to
     just MSG_MORE on the last call to ->sendpage().

 (3) Make ceph_tcp_sendpage() a wrapper around sendmsg() rather than
     sendpage(), setting MSG_SPLICE_PAGES if sendpage_ok() returns true on
     the page.

In messenger_v2:

 (4) Bring back do_try_sendpage() and make the callers use that.

 (5) Make do_try_sendpage() use sendmsg() for both cases and set
     MSG_SPLICE_PAGES if sendpage_ok() is set.

Fixes: 40a8c17aa7 ("ceph: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage")
Fixes: fa094ccae1 ("ceph: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage()")
Reported-by: Ilya Dryomov <idryomov@gmail.com>
Link: https://lore.kernel.org/r/CAOi1vP9vjLfk3W+AJFeexC93jqPaPUn2dD_4NrzxwoZTbYfOnw@mail.gmail.com/
Link: https://lore.kernel.org/r/CAOi1vP_Bn918j24S94MuGyn+Gxk212btw7yWeDrRcW1U8pc_BA@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.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/3101881.1687801973@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/3111635.1687813501@warthog.procyon.org.uk/ # v2
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Link: https://lore.kernel.org/r/3199652.1687873788@warthog.procyon.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
David Howells 2023-06-27 14:49:48 +01:00 committed by Jakub Kicinski
parent 528a08bcd8
commit 5da4d7b8e6
2 changed files with 107 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
net/ceph/messenger_v1.c
View File

@ -74,6 +74,39 @@ static int ceph_tcp_sendmsg(struct socket *sock, struct kvec *iov,
return r;
}
/*
* @more: MSG_MORE or 0.
*/
static int ceph_tcp_sendpage(struct socket *sock, struct page *page,
int offset, size_t size, int more)
{
struct msghdr msg = {
.msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL | more,
};
struct bio_vec bvec;
int ret;
/*
* MSG_SPLICE_PAGES 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(page))
msg.msg_flags |= MSG_SPLICE_PAGES;
bvec_set_page(&bvec, page, size, offset);
iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);
ret = sock_sendmsg(sock, &msg);
if (ret == -EAGAIN)
ret = 0;
return ret;
}
static void con_out_kvec_reset(struct ceph_connection *con)
{
BUG_ON(con->v1.out_skip);
@ -450,10 +483,6 @@ static int write_partial_message_data(struct ceph_connection *con)
*/
crc = do_datacrc ? le32_to_cpu(msg->footer.data_crc) : 0;
while (cursor->total_resid) {
struct bio_vec bvec;
struct msghdr msghdr = {
.msg_flags = MSG_SPLICE_PAGES,
};
struct page *page;
size_t page_offset;
size_t length;
@ -465,13 +494,8 @@ static int write_partial_message_data(struct ceph_connection *con)
}
page = ceph_msg_data_next(cursor, &page_offset, &length);
if (length != cursor->total_resid)
msghdr.msg_flags |= MSG_MORE;
bvec_set_page(&bvec, page, length, page_offset);
iov_iter_bvec(&msghdr.msg_iter, ITER_SOURCE, &bvec, 1, length);
ret = sock_sendmsg(con->sock, &msghdr);
ret = ceph_tcp_sendpage(con->sock, page, page_offset, length,
MSG_MORE);
if (ret <= 0) {
if (do_datacrc)
msg->footer.data_crc = cpu_to_le32(crc);
@ -501,22 +525,14 @@ static int write_partial_message_data(struct ceph_connection *con)
*/
static int write_partial_skip(struct ceph_connection *con)
{
struct bio_vec bvec;
struct msghdr msghdr = {
.msg_flags = MSG_SPLICE_PAGES | MSG_MORE,
};
int ret;
dout("%s %p %d left\n", __func__, con, con->v1.out_skip);
while (con->v1.out_skip > 0) {
size_t size = min(con->v1.out_skip, (int)PAGE_SIZE);
if (size == con->v1.out_skip)
msghdr.msg_flags &= ~MSG_MORE;
bvec_set_page(&bvec, ZERO_PAGE(0), size, 0);
iov_iter_bvec(&msghdr.msg_iter, ITER_SOURCE, &bvec, 1, size);
ret = sock_sendmsg(con->sock, &msghdr);
ret = ceph_tcp_sendpage(con->sock, ceph_zero_page, 0, size,
MSG_MORE);
if (ret <= 0)
goto out;
con->v1.out_skip -= ret;

88
net/ceph/messenger_v2.c
View File

@ -117,38 +117,90 @@ 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);
/*
* MSG_SPLICE_PAGES 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))
msg.msg_flags |= MSG_SPLICE_PAGES;
else
msg.msg_flags &= ~MSG_SPLICE_PAGES;
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 here.
*
* Return:
* >0 - done, nothing (else) to write
* 1 - 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);
ret = sock_sendmsg(con->sock, &msg);
if (ret > 0)
iov_iter_advance(&con->v2.out_iter, ret);
else if (ret == -EAGAIN)
ret = 0;
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);
dout("%s con %p ret %d left %zu\n", __func__, con, ret,
iov_iter_count(&con->v2.out_iter));
return ret;