nvmet-fc: Better size LS buffers

Current code uses NVME_FC_MAX_LS_BUFFER_SIZE (2KB) when allocating
buffers for LS requests and responses. This is considerable overkill
for what is actually defined.

Rework code to have unions for all possible requests and responses
and size based on the unions.  Remove NVME_FC_MAX_LS_BUFFER_SIZE.

Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 38 insertions, 30 deletions

diff --git a/drivers/nvme/host/fc.h b/drivers/nvme/host/fc.h
index d2861cdd58ee..08fa88381d45 100644
--- a/drivers/nvme/host/fc.h
+++ b/drivers/nvme/host/fc.h
@@ -16,6 +16,21 @@
  * ******************  FC-NVME LS HANDLING ******************
  */
 
+union nvmefc_ls_requests {
+	struct fcnvme_ls_cr_assoc_rqst		rq_cr_assoc;
+	struct fcnvme_ls_cr_conn_rqst		rq_cr_conn;
+	struct fcnvme_ls_disconnect_assoc_rqst	rq_dis_assoc;
+	struct fcnvme_ls_disconnect_conn_rqst	rq_dis_conn;
+} __aligned(128);	/* alignment for other things alloc'd with */
+
+union nvmefc_ls_responses {
+	struct fcnvme_ls_rjt			rsp_rjt;
+	struct fcnvme_ls_cr_assoc_acc		rsp_cr_assoc;
+	struct fcnvme_ls_cr_conn_acc		rsp_cr_conn;
+	struct fcnvme_ls_disconnect_assoc_acc	rsp_dis_assoc;
+	struct fcnvme_ls_disconnect_conn_acc	rsp_dis_conn;
+} __aligned(128);	/* alignment for other things alloc'd with */
+
 static inline void
 nvme_fc_format_rsp_hdr(void *buf, u8 ls_cmd, __be32 desc_len, u8 rqst_ls_cmd)
 {
diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
index 1f3118a3b0a3..66de6bd8f4fd 100644
--- a/drivers/nvme/target/fc.c
+++ b/drivers/nvme/target/fc.c
@@ -22,9 +22,6 @@
 
 #define NVMET_LS_CTX_COUNT		256
 
-/* for this implementation, assume small single frame rqst/rsp */
-#define NVME_FC_MAX_LS_BUFFER_SIZE		2048
-
 struct nvmet_fc_tgtport;
 struct nvmet_fc_tgt_assoc;
 
@@ -37,8 +34,8 @@ struct nvmet_fc_ls_iod {
 	struct nvmet_fc_tgtport		*tgtport;
 	struct nvmet_fc_tgt_assoc	*assoc;
 
-	u8				*rqstbuf;
-	u8				*rspbuf;
+	union nvmefc_ls_requests	*rqstbuf;
+	union nvmefc_ls_responses	*rspbuf;
 	u16				rqstdatalen;
 	dma_addr_t			rspdma;
 
@@ -340,15 +337,16 @@ nvmet_fc_alloc_ls_iodlist(struct nvmet_fc_tgtport *tgtport)
 		iod->tgtport = tgtport;
 		list_add_tail(&iod->ls_list, &tgtport->ls_list);
 
-		iod->rqstbuf = kcalloc(2, NVME_FC_MAX_LS_BUFFER_SIZE,
-			GFP_KERNEL);
+		iod->rqstbuf = kzalloc(sizeof(union nvmefc_ls_requests) +
+				       sizeof(union nvmefc_ls_responses),
+				       GFP_KERNEL);
 		if (!iod->rqstbuf)
 			goto out_fail;
 
-		iod->rspbuf = iod->rqstbuf + NVME_FC_MAX_LS_BUFFER_SIZE;
+		iod->rspbuf = (union nvmefc_ls_responses *)&iod->rqstbuf[1];
 
 		iod->rspdma = fc_dma_map_single(tgtport->dev, iod->rspbuf,
-						NVME_FC_MAX_LS_BUFFER_SIZE,
+						sizeof(*iod->rspbuf),
 						DMA_TO_DEVICE);
 		if (fc_dma_mapping_error(tgtport->dev, iod->rspdma))
 			goto out_fail;
@@ -361,7 +359,7 @@ out_fail:
 	list_del(&iod->ls_list);
 	for (iod--, i--; i >= 0; iod--, i--) {
 		fc_dma_unmap_single(tgtport->dev, iod->rspdma,
-				NVME_FC_MAX_LS_BUFFER_SIZE, DMA_TO_DEVICE);
+				sizeof(*iod->rspbuf), DMA_TO_DEVICE);
 		kfree(iod->rqstbuf);
 		list_del(&iod->ls_list);
 	}
@@ -379,7 +377,7 @@ nvmet_fc_free_ls_iodlist(struct nvmet_fc_tgtport *tgtport)
 
 	for (i = 0; i < NVMET_LS_CTX_COUNT; iod++, i++) {
 		fc_dma_unmap_single(tgtport->dev,
-				iod->rspdma, NVME_FC_MAX_LS_BUFFER_SIZE,
+				iod->rspdma, sizeof(*iod->rspbuf),
 				DMA_TO_DEVICE);
 		kfree(iod->rqstbuf);
 		list_del(&iod->ls_list);
@@ -1262,10 +1260,8 @@ static void
 nvmet_fc_ls_create_association(struct nvmet_fc_tgtport *tgtport,
 			struct nvmet_fc_ls_iod *iod)
 {
-	struct fcnvme_ls_cr_assoc_rqst *rqst =
-				(struct fcnvme_ls_cr_assoc_rqst *)iod->rqstbuf;
-	struct fcnvme_ls_cr_assoc_acc *acc =
-				(struct fcnvme_ls_cr_assoc_acc *)iod->rspbuf;
+	struct fcnvme_ls_cr_assoc_rqst *rqst = &iod->rqstbuf->rq_cr_assoc;
+	struct fcnvme_ls_cr_assoc_acc *acc = &iod->rspbuf->rsp_cr_assoc;
 	struct nvmet_fc_tgt_queue *queue;
 	int ret = 0;
 
@@ -1313,7 +1309,7 @@ nvmet_fc_ls_create_association(struct nvmet_fc_tgtport *tgtport,
 			"Create Association LS failed: %s\n",
 			validation_errors[ret]);
 		iod->lsrsp->rsplen = nvme_fc_format_rjt(acc,
-				NVME_FC_MAX_LS_BUFFER_SIZE, rqst->w0.ls_cmd,
+				sizeof(*acc), rqst->w0.ls_cmd,
 				FCNVME_RJT_RC_LOGIC,
 				FCNVME_RJT_EXP_NONE, 0);
 		return;
@@ -1348,10 +1344,8 @@ static void
 nvmet_fc_ls_create_connection(struct nvmet_fc_tgtport *tgtport,
 			struct nvmet_fc_ls_iod *iod)
 {
-	struct fcnvme_ls_cr_conn_rqst *rqst =
-				(struct fcnvme_ls_cr_conn_rqst *)iod->rqstbuf;
-	struct fcnvme_ls_cr_conn_acc *acc =
-				(struct fcnvme_ls_cr_conn_acc *)iod->rspbuf;
+	struct fcnvme_ls_cr_conn_rqst *rqst = &iod->rqstbuf->rq_cr_conn;
+	struct fcnvme_ls_cr_conn_acc *acc = &iod->rspbuf->rsp_cr_conn;
 	struct nvmet_fc_tgt_queue *queue;
 	int ret = 0;
 
@@ -1404,7 +1398,7 @@ nvmet_fc_ls_create_connection(struct nvmet_fc_tgtport *tgtport,
 			"Create Connection LS failed: %s\n",
 			validation_errors[ret]);
 		iod->lsrsp->rsplen = nvme_fc_format_rjt(acc,
-				NVME_FC_MAX_LS_BUFFER_SIZE, rqst->w0.ls_cmd,
+				sizeof(*acc), rqst->w0.ls_cmd,
 				(ret == VERR_NO_ASSOC) ?
 					FCNVME_RJT_RC_INV_ASSOC :
 					FCNVME_RJT_RC_LOGIC,
@@ -1437,9 +1431,9 @@ nvmet_fc_ls_disconnect(struct nvmet_fc_tgtport *tgtport,
 			struct nvmet_fc_ls_iod *iod)
 {
 	struct fcnvme_ls_disconnect_assoc_rqst *rqst =
-			(struct fcnvme_ls_disconnect_assoc_rqst *)iod->rqstbuf;
+						&iod->rqstbuf->rq_dis_assoc;
 	struct fcnvme_ls_disconnect_assoc_acc *acc =
-			(struct fcnvme_ls_disconnect_assoc_acc *)iod->rspbuf;
+						&iod->rspbuf->rsp_dis_assoc;
 	struct nvmet_fc_tgt_assoc *assoc;
 	int ret = 0;
 
@@ -1484,7 +1478,7 @@ nvmet_fc_ls_disconnect(struct nvmet_fc_tgtport *tgtport,
 			"Disconnect LS failed: %s\n",
 			validation_errors[ret]);
 		iod->lsrsp->rsplen = nvme_fc_format_rjt(acc,
-				NVME_FC_MAX_LS_BUFFER_SIZE, rqst->w0.ls_cmd,
+				sizeof(*acc), rqst->w0.ls_cmd,
 				(ret == VERR_NO_ASSOC) ?
 					FCNVME_RJT_RC_INV_ASSOC :
 					FCNVME_RJT_RC_LOGIC,
@@ -1522,7 +1516,7 @@ nvmet_fc_xmt_ls_rsp_done(struct nvmefc_ls_rsp *lsrsp)
 	struct nvmet_fc_tgtport *tgtport = iod->tgtport;
 
 	fc_dma_sync_single_for_cpu(tgtport->dev, iod->rspdma,
-				NVME_FC_MAX_LS_BUFFER_SIZE, DMA_TO_DEVICE);
+				sizeof(*iod->rspbuf), DMA_TO_DEVICE);
 	nvmet_fc_free_ls_iod(tgtport, iod);
 	nvmet_fc_tgtport_put(tgtport);
 }
@@ -1534,7 +1528,7 @@ nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport,
 	int ret;
 
 	fc_dma_sync_single_for_device(tgtport->dev, iod->rspdma,
-				  NVME_FC_MAX_LS_BUFFER_SIZE, DMA_TO_DEVICE);
+				  sizeof(*iod->rspbuf), DMA_TO_DEVICE);
 
 	ret = tgtport->ops->xmt_ls_rsp(&tgtport->fc_target_port, iod->lsrsp);
 	if (ret)
@@ -1548,8 +1542,7 @@ static void
 nvmet_fc_handle_ls_rqst(struct nvmet_fc_tgtport *tgtport,
 			struct nvmet_fc_ls_iod *iod)
 {
-	struct fcnvme_ls_rqst_w0 *w0 =
-			(struct fcnvme_ls_rqst_w0 *)iod->rqstbuf;
+	struct fcnvme_ls_rqst_w0 *w0 = &iod->rqstbuf->rq_cr_assoc.w0;
 
 	iod->lsrsp->nvme_fc_private = iod;
 	iod->lsrsp->rspbuf = iod->rspbuf;
@@ -1580,7 +1573,7 @@ nvmet_fc_handle_ls_rqst(struct nvmet_fc_tgtport *tgtport,
 		break;
 	default:
 		iod->lsrsp->rsplen = nvme_fc_format_rjt(iod->rspbuf,
-				NVME_FC_MAX_LS_BUFFER_SIZE, w0->ls_cmd,
+				sizeof(*iod->rspbuf), w0->ls_cmd,
 				FCNVME_RJT_RC_INVAL, FCNVME_RJT_EXP_NONE, 0);
 	}
 
@@ -1627,7 +1620,7 @@ nvmet_fc_rcv_ls_req(struct nvmet_fc_target_port *target_port,
 	struct nvmet_fc_tgtport *tgtport = targetport_to_tgtport(target_port);
 	struct nvmet_fc_ls_iod *iod;
 
-	if (lsreqbuf_len > NVME_FC_MAX_LS_BUFFER_SIZE)
+	if (lsreqbuf_len > sizeof(union nvmefc_ls_requests))
 		return -E2BIG;
 
 	if (!nvmet_fc_tgtport_get(tgtport))