nvme: rewrite discard support

This rewrites nvme_setup_discard() with blk_add_request_payload().
It allocates only the necessary amount(16 bytes) for the payload.

Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index d23ede73537dcbf35c417691e246c1c8615c3bf6..0bf7f61a0a89edbf67a53ccea50de19be9cf869c 100644 (file)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -363,6 +363,9 @@ static void nvme_free_iod(struct nvme_dev *dev, struct request *req)
        __le64 **list = iod_list(req);
        dma_addr_t prp_dma = iod->first_dma;
 
+       if (req->cmd_flags & REQ_DISCARD)
+               kfree(req->completion_data);
+
        if (iod->npages == 0)
                dma_pool_free(dev->prp_small_pool, list[0], prp_dma);
        for (i = 0; i < iod->npages; i++) {
@@ -524,7 +527,7 @@ static bool nvme_setup_prps(struct nvme_dev *dev, struct request *req,
 }
 
 static int nvme_map_data(struct nvme_dev *dev, struct request *req,
-               struct nvme_command *cmnd)
+               unsigned size, struct nvme_command *cmnd)
 {
        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct request_queue *q = req->q;
@@ -541,7 +544,7 @@ static int nvme_map_data(struct nvme_dev *dev, struct request *req,
        if (!dma_map_sg(dev->dev, iod->sg, iod->nents, dma_dir))
                goto out;
 
-       if (!nvme_setup_prps(dev, req, blk_rq_bytes(req)))
+       if (!nvme_setup_prps(dev, req, size))
                goto out_unmap;
 
        ret = BLK_MQ_RQ_QUEUE_ERROR;
@@ -590,35 +593,41 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
        nvme_free_iod(dev, req);
 }
 
-/*
- * We reuse the small pool to allocate the 16-byte range here as it is not
- * worth having a special pool for these or additional cases to handle freeing
- * the iod.
- */
-static int nvme_setup_discard(struct nvme_queue *nvmeq, struct nvme_ns *ns,
-               struct request *req, struct nvme_command *cmnd)
+static inline int nvme_setup_discard(struct nvme_ns *ns, struct request *req,
+               struct nvme_command *cmnd)
 {
-       struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
        struct nvme_dsm_range *range;
+       struct page *page;
+       int offset;
+       unsigned int nr_bytes = blk_rq_bytes(req);
 
-       range = dma_pool_alloc(nvmeq->dev->prp_small_pool, GFP_ATOMIC,
-                                               &iod->first_dma);
+       range = kmalloc(sizeof(*range), GFP_ATOMIC);
        if (!range)
                return BLK_MQ_RQ_QUEUE_BUSY;
-       iod_list(req)[0] = (__le64 *)range;
-       iod->npages = 0;
 
        range->cattr = cpu_to_le32(0);
-       range->nlb = cpu_to_le32(blk_rq_bytes(req) >> ns->lba_shift);
+       range->nlb = cpu_to_le32(nr_bytes >> ns->lba_shift);
        range->slba = cpu_to_le64(nvme_block_nr(ns, blk_rq_pos(req)));
 
        memset(cmnd, 0, sizeof(*cmnd));
        cmnd->dsm.opcode = nvme_cmd_dsm;
        cmnd->dsm.nsid = cpu_to_le32(ns->ns_id);
-       cmnd->dsm.prp1 = cpu_to_le64(iod->first_dma);
        cmnd->dsm.nr = 0;
        cmnd->dsm.attributes = cpu_to_le32(NVME_DSMGMT_AD);
-       return BLK_MQ_RQ_QUEUE_OK;
+
+       req->completion_data = range;
+       page = virt_to_page(range);
+       offset = offset_in_page(range);
+       blk_add_request_payload(req, page, offset, sizeof(*range));
+
+       /*
+        * we set __data_len back to the size of the area to be discarded
+        * on disk. This allows us to report completion on the full amount
+        * of blocks described by the request.
+        */
+       req->__data_len = nr_bytes;
+
+       return 0;
 }
 
 /*
@@ -653,19 +662,20 @@ static int nvme_queue_rq(struct blk_mq_hw_ctx *hctx,
        if (ret)
                return ret;
 
-       if (req->cmd_flags & REQ_DISCARD) {
-               ret = nvme_setup_discard(nvmeq, ns, req, &cmnd);
-       } else {
-               if (req->cmd_type == REQ_TYPE_DRV_PRIV)
-                       memcpy(&cmnd, req->cmd, sizeof(cmnd));
-               else if (req->cmd_flags & REQ_FLUSH)
-                       nvme_setup_flush(ns, &cmnd);
-               else
-                       nvme_setup_rw(ns, req, &cmnd);
+       if (req->cmd_type == REQ_TYPE_DRV_PRIV)
+               memcpy(&cmnd, req->cmd, sizeof(cmnd));
+       else if (req->cmd_flags & REQ_FLUSH)
+               nvme_setup_flush(ns, &cmnd);
+       else if (req->cmd_flags & REQ_DISCARD)
+               ret = nvme_setup_discard(ns, req, &cmnd);
+       else
+               nvme_setup_rw(ns, req, &cmnd);
 
-               if (req->nr_phys_segments)
-                       ret = nvme_map_data(dev, req, &cmnd);
-       }
+       if (ret)
+               goto out;
+
+       if (req->nr_phys_segments)
+               ret = nvme_map_data(dev, req, map_len, &cmnd);
 
        if (ret)
                goto out;