[Patch v2 13/19] CIFS: SMBD: Use registered memory RDMA read for SMB write

Long Li
2017-08-20T19:04:37Z

From: Long Li <longli@microsoft.com>

When sending I/O, if size is larger than rdma_readwrite_threshold we prepare to send SMB WRITE packet for a RDMA read via memory registration. The actual I/O is done out-of-the-band, so modify the relevant fields in the packet accordingly.

Signed-off-by: Long Li <longli@microsoft.com>
---
fs/cifs/smb2pdu.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 5cc5f6c..5581afd 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -48,6 +48,7 @@
#include "smb2glob.h"
#include "cifspdu.h"
#include "cifs_spnego.h"
+#include "smbdirect.h"

/*
* The following table defines the expected "StructureSize" of SMB2 requests
@@ -2716,6 +2717,41 @@ smb2_async_writev(struct cifs_writedata *wdata,
offsetof(struct smb2_write_req, Buffer) - 4);
req->RemainingBytes = 0;

+ /*
+ * If we want to do a server RDMA read, fill in and append
+ * smbd_buffer_descriptor_v1 to the end of write request
+ */
+ if (server->rdma && wdata->bytes >
+ server->smbd_conn->rdma_readwrite_threshold) {
+
+ struct smbd_buffer_descriptor_v1 *v1;
+ bool need_invalidate = server->dialect == SMB30_PROT_ID;
+
+ wdata->mr = smbd_register_mr(
+ server->smbd_conn, wdata->pages,
+ wdata->nr_pages, wdata->tailsz,
+ false, need_invalidate);
+ if (!wdata->mr) {
+ rc = -ENOBUFS;
+ goto async_writev_out;
+ }
+ req->Length = 0;
+ req->DataOffset = 0;
+ req->RemainingBytes =
+ (wdata->nr_pages-1)*PAGE_SIZE + wdata->tailsz;
+ req->Channel = SMB2_CHANNEL_RDMA_V1_INVALIDATE;
+ if (need_invalidate)
+ req->Channel = SMB2_CHANNEL_RDMA_V1;
+ req->WriteChannelInfoOffset =
+ offsetof(struct smb2_write_req, Buffer) - 4;
+ req->WriteChannelInfoLength =
+ sizeof(struct smbd_buffer_descriptor_v1);
+ v1 = (struct smbd_buffer_descriptor_v1 *) &req->Buffer[0];
+ v1->offset = wdata->mr->mr->iova;
+ v1->token = wdata->mr->mr->rkey;
+ v1->length = wdata->mr->mr->length;
+ }
+
/* 4 for rfc1002 length field and 1 for Buffer */
iov[0].iov_len = 4;
iov[0].iov_base = req;
@@ -2729,10 +2765,17 @@ smb2_async_writev(struct cifs_writedata *wdata,
rqst.rq_pagesz = wdata->pagesz;
rqst.rq_tailsz = wdata->tailsz;

+ if (wdata->mr) {
+ iov[1].iov_len += sizeof(struct smbd_buffer_descriptor_v1);
+ rqst.rq_npages = 0;
+ }
+
cifs_dbg(FYI, "async write at %llu %u bytes\n",
wdata->offset, wdata->bytes);

- req->Length = cpu_to_le32(wdata->bytes);
+ /* For RDMA read, I/O size is in RemainingBytes not in Length */
+ if (!wdata->mr)
+ req->Length = cpu_to_le32(wdata->bytes);

inc_rfc1001_len(&req->hdr, wdata->bytes - 1 /* Buffer */);

--
2.7.4