From: Long Li <[email protected]> SMB client and server maintain a credit system on the SMBD transport. Credits are used to tell when the client or server can send a packet to the peer, based on current memory or resource usage.
Signed-off-by: Long Li <[email protected]> --- fs/cifs/cifsrdma.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/fs/cifs/cifsrdma.c b/fs/cifs/cifsrdma.c index eb48651..97cde3f 100644 --- a/fs/cifs/cifsrdma.c +++ b/fs/cifs/cifsrdma.c @@ -575,6 +575,46 @@ static int cifs_rdma_post_send_negotiate_req(struct cifs_rdma_info *info) } /* + * Extend the credits to remote peer + * This implements [MS-SMBD] 3.1.5.9 + * The idea is that we should extend credits to remote peer as quickly as + * it's allowed, to maintain data flow. We allocate as much as receive + * buffer as possible, and extend the receive credits to remote peer + * return value: the new credtis being granted. + */ +static int manage_credits_prior_sending(struct cifs_rdma_info *info) +{ + int ret = 0; + struct cifs_rdma_response *response; + int rc; + + if (atomic_read(&info->receive_credit_target) > + atomic_read(&info->receive_credits)) { + while (true) { + response = get_receive_buffer(info); + if (!response) + break; + + response->type = SMBD_TRANSFER_DATA; + response->first_segment = false; + rc = cifs_rdma_post_recv(info, response); + if (rc) { + log_rdma_recv("post_recv failed rc=%d\n", rc); + put_receive_buffer(info, response); + break; + } + + ret++; + } + } + + atomic_add(ret, &info->receive_credits); + log_transport_credit(info); + + return ret; +} + +/* * Send a page * page: the page to send * offset: offset in the page to send @@ -607,6 +647,8 @@ static int cifs_rdma_post_send_page(struct cifs_rdma_info *info, struct page *pa packet = (struct smbd_data_transfer *) request->packet; packet->credits_requested = cpu_to_le16(info->send_credit_target); + packet->credits_granted = + cpu_to_le16(manage_credits_prior_sending(info)); packet->flags = cpu_to_le16(0); packet->reserved = cpu_to_le16(0); @@ -718,6 +760,8 @@ static int cifs_rdma_post_send_empty(struct cifs_rdma_info *info) request->info = info; packet = (struct smbd_data_transfer_no_data *) request->packet; + credits_granted = manage_credits_prior_sending(info); + /* nothing to do? */ if (credits_granted==0 && flags==0) { mempool_free(request, info->request_mempool); @@ -827,6 +871,7 @@ static int cifs_rdma_post_send_data( packet = (struct smbd_data_transfer *) request->packet; packet->credits_requested = cpu_to_le16(info->send_credit_target); + packet->credits_granted = cpu_to_le16(manage_credits_prior_sending(info)); packet->flags = cpu_to_le16(0); packet->reserved = cpu_to_le16(0); -- 2.7.4
