Re: [PATCH v3 12/26] xprtrdma: Port to new memory registration API

[Anna Schumaker <Anna.Schumaker@netapp.com>]

Hi Sagi,

On 10/08/2015 03:50 AM, Sagi Grimberg wrote:
> Instead of maintaining a fastreg page list, keep an sg table
> and convert an array of pages to a sg list. Then call ib_map_mr_sg
> and construct ib_reg_wr.
> 
> Note that the next step would be to have NFS work with sg lists
> as it maps well to sk_frags (see comment from hch
> http://marc.info/?l=linux-rdma&m=143677002622296&w=2).

Looks good to me!

Acked-by: Anna Schumaker <anna.schumaker@netapp.com>
> 
> Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
> Acked-by: Christoph Hellwig <hch@lst.de>
> Tested-by: Steve Wise <swise@opengridcomputing.com>
> Tested-by: Selvin Xavier <selvin.xavier@avagotech.com>
> ---
>  net/sunrpc/xprtrdma/frwr_ops.c  | 112 +++++++++++++++++++++++-----------------
>  net/sunrpc/xprtrdma/xprt_rdma.h |   3 +-
>  2 files changed, 67 insertions(+), 48 deletions(-)
> 
> diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
> index 0d2f46f600b6..3c89f8052786 100644
> --- a/net/sunrpc/xprtrdma/frwr_ops.c
> +++ b/net/sunrpc/xprtrdma/frwr_ops.c
> @@ -151,9 +151,13 @@ __frwr_init(struct rpcrdma_mw *r, struct ib_pd *pd, struct ib_device *device,
>  	f->fr_mr = ib_alloc_mr(pd, IB_MR_TYPE_MEM_REG, depth);
>  	if (IS_ERR(f->fr_mr))
>  		goto out_mr_err;
> -	f->fr_pgl = ib_alloc_fast_reg_page_list(device, depth);
> -	if (IS_ERR(f->fr_pgl))
> +
> +	f->sg = kcalloc(depth, sizeof(*f->sg), GFP_KERNEL);
> +	if (!f->sg)
>  		goto out_list_err;
> +
> +	sg_init_table(f->sg, depth);
> +
>  	return 0;
>  
>  out_mr_err:
> @@ -163,7 +167,7 @@ out_mr_err:
>  	return rc;
>  
>  out_list_err:
> -	rc = PTR_ERR(f->fr_pgl);
> +	rc = -ENOMEM;
>  	dprintk("RPC:       %s: ib_alloc_fast_reg_page_list status %i\n",
>  		__func__, rc);
>  	ib_dereg_mr(f->fr_mr);
> @@ -179,7 +183,7 @@ __frwr_release(struct rpcrdma_mw *r)
>  	if (rc)
>  		dprintk("RPC:       %s: ib_dereg_mr status %i\n",
>  			__func__, rc);
> -	ib_free_fast_reg_page_list(r->r.frmr.fr_pgl);
> +	kfree(r->r.frmr.sg);
>  }
>  
>  static int
> @@ -312,14 +316,11 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
>  	struct rpcrdma_mw *mw;
>  	struct rpcrdma_frmr *frmr;
>  	struct ib_mr *mr;
> -	struct ib_fast_reg_wr fastreg_wr;
> +	struct ib_reg_wr reg_wr;
>  	struct ib_send_wr *bad_wr;
> +	unsigned int dma_nents;
>  	u8 key;
> -	int len, pageoff;
> -	int i, rc;
> -	int seg_len;
> -	u64 pa;
> -	int page_no;
> +	int i, rc, len, n;
>  
>  	mw = seg1->rl_mw;
>  	seg1->rl_mw = NULL;
> @@ -332,64 +333,81 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
>  	} while (mw->r.frmr.fr_state != FRMR_IS_INVALID);
>  	frmr = &mw->r.frmr;
>  	frmr->fr_state = FRMR_IS_VALID;
> +	mr = frmr->fr_mr;
>  
> -	pageoff = offset_in_page(seg1->mr_offset);
> -	seg1->mr_offset -= pageoff;	/* start of page */
> -	seg1->mr_len += pageoff;
> -	len = -pageoff;
>  	if (nsegs > ia->ri_max_frmr_depth)
>  		nsegs = ia->ri_max_frmr_depth;
>  
> -	for (page_no = i = 0; i < nsegs;) {
> -		rpcrdma_map_one(device, seg, direction);
> -		pa = seg->mr_dma;
> -		for (seg_len = seg->mr_len; seg_len > 0; seg_len -= PAGE_SIZE) {
> -			frmr->fr_pgl->page_list[page_no++] = pa;
> -			pa += PAGE_SIZE;
> -		}
> +	for (len = 0, i = 0; i < nsegs;) {
> +		if (seg->mr_page)
> +			sg_set_page(&frmr->sg[i],
> +				    seg->mr_page,
> +				    seg->mr_len,
> +				    offset_in_page(seg->mr_offset));
> +		else
> +			sg_set_buf(&frmr->sg[i], seg->mr_offset,
> +				   seg->mr_len);
> +
>  		len += seg->mr_len;
>  		++seg;
>  		++i;
> +
>  		/* Check for holes */
>  		if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
>  		    offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
>  			break;
>  	}
> +	frmr->sg_nents = i;
> +
> +	dma_nents = ib_dma_map_sg(device, frmr->sg, frmr->sg_nents, direction);
> +	if (!dma_nents) {
> +		pr_err("RPC:       %s: failed to dma map sg %p sg_nents %d\n",
> +		       __func__, frmr->sg, frmr->sg_nents);
> +		return -ENOMEM;
> +	}
> +
> +	n = ib_map_mr_sg(mr, frmr->sg, frmr->sg_nents, PAGE_SIZE);
> +	if (unlikely(n != frmr->sg_nents)) {
> +		pr_err("RPC:       %s: failed to map mr %p (%d/%d)\n",
> +		       __func__, frmr->fr_mr, n, frmr->sg_nents);
> +		rc = n < 0 ? n : -EINVAL;
> +		goto out_senderr;
> +	}
> +
>  	dprintk("RPC:       %s: Using frmr %p to map %d segments (%d bytes)\n",
> -		__func__, mw, i, len);
> -
> -	memset(&fastreg_wr, 0, sizeof(fastreg_wr));
> -	fastreg_wr.wr.wr_id = (unsigned long)(void *)mw;
> -	fastreg_wr.wr.opcode = IB_WR_FAST_REG_MR;
> -	fastreg_wr.iova_start = seg1->mr_dma + pageoff;
> -	fastreg_wr.page_list = frmr->fr_pgl;
> -	fastreg_wr.page_shift = PAGE_SHIFT;
> -	fastreg_wr.page_list_len = page_no;
> -	fastreg_wr.length = len;
> -	fastreg_wr.access_flags = writing ?
> -				IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
> -				IB_ACCESS_REMOTE_READ;
> -	mr = frmr->fr_mr;
> +		__func__, mw, frmr->sg_nents, mr->length);
> +
>  	key = (u8)(mr->rkey & 0x000000FF);
>  	ib_update_fast_reg_key(mr, ++key);
> -	fastreg_wr.rkey = mr->rkey;
> +
> +	reg_wr.wr.next = NULL;
> +	reg_wr.wr.opcode = IB_WR_REG_MR;
> +	reg_wr.wr.wr_id = (uintptr_t)mw;
> +	reg_wr.wr.num_sge = 0;
> +	reg_wr.wr.send_flags = 0;
> +	reg_wr.mr = mr;
> +	reg_wr.key = mr->rkey;
> +	reg_wr.access = writing ?
> +			IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
> +			IB_ACCESS_REMOTE_READ;
>  
>  	DECR_CQCOUNT(&r_xprt->rx_ep);
> -	rc = ib_post_send(ia->ri_id->qp, &fastreg_wr.wr, &bad_wr);
> +	rc = ib_post_send(ia->ri_id->qp, &reg_wr.wr, &bad_wr);
>  	if (rc)
>  		goto out_senderr;
>  
> +	seg1->mr_dir = direction;
>  	seg1->rl_mw = mw;
>  	seg1->mr_rkey = mr->rkey;
> -	seg1->mr_base = seg1->mr_dma + pageoff;
> -	seg1->mr_nsegs = i;
> -	seg1->mr_len = len;
> -	return i;
> +	seg1->mr_base = mr->iova;
> +	seg1->mr_nsegs = frmr->sg_nents;
> +	seg1->mr_len = mr->length;
> +
> +	return frmr->sg_nents;
>  
>  out_senderr:
>  	dprintk("RPC:       %s: ib_post_send status %i\n", __func__, rc);
> -	while (i--)
> -		rpcrdma_unmap_one(device, --seg);
> +	ib_dma_unmap_sg(device, frmr->sg, frmr->sg_nents, direction);
>  	__frwr_queue_recovery(mw);
>  	return rc;
>  }
> @@ -403,22 +421,22 @@ frwr_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
>  	struct rpcrdma_mr_seg *seg1 = seg;
>  	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
>  	struct rpcrdma_mw *mw = seg1->rl_mw;
> +	struct rpcrdma_frmr *frmr = &mw->r.frmr;
>  	struct ib_send_wr invalidate_wr, *bad_wr;
>  	int rc, nsegs = seg->mr_nsegs;
>  
>  	dprintk("RPC:       %s: FRMR %p\n", __func__, mw);
>  
>  	seg1->rl_mw = NULL;
> -	mw->r.frmr.fr_state = FRMR_IS_INVALID;
> +	frmr->fr_state = FRMR_IS_INVALID;
>  
>  	memset(&invalidate_wr, 0, sizeof(invalidate_wr));
>  	invalidate_wr.wr_id = (unsigned long)(void *)mw;
>  	invalidate_wr.opcode = IB_WR_LOCAL_INV;
> -	invalidate_wr.ex.invalidate_rkey = mw->r.frmr.fr_mr->rkey;
> +	invalidate_wr.ex.invalidate_rkey = frmr->fr_mr->rkey;
>  	DECR_CQCOUNT(&r_xprt->rx_ep);
>  
> -	while (seg1->mr_nsegs--)
> -		rpcrdma_unmap_one(ia->ri_device, seg++);
> +	ib_dma_unmap_sg(ia->ri_device, frmr->sg, frmr->sg_nents, seg1->mr_dir);
>  	read_lock(&ia->ri_qplock);
>  	rc = ib_post_send(ia->ri_id->qp, &invalidate_wr, &bad_wr);
>  	read_unlock(&ia->ri_qplock);
> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
> index c09414e6f91b..426a9107c0ff 100644
> --- a/net/sunrpc/xprtrdma/xprt_rdma.h
> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h
> @@ -193,7 +193,8 @@ enum rpcrdma_frmr_state {
>  };
>  
>  struct rpcrdma_frmr {
> -	struct ib_fast_reg_page_list	*fr_pgl;
> +	struct scatterlist		*sg;
> +	unsigned int			sg_nents;
>  	struct ib_mr			*fr_mr;
>  	enum rpcrdma_frmr_state		fr_state;
>  	struct work_struct		fr_work;
>