NVMe: Add discard support for capable devices

This adds discard support to block queues if the nvme device is capable of
deallocating blocks as indicated by the controller's optional command support.
A discard flagged bio request will submit an NVMe deallocate Data Set
Management command for the requested blocks.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

1 files changed, 59 insertions, 1 deletions

diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c
index 9dcefe40380b..26e266072079 100644
--- a/drivers/block/nvme.c
+++ b/drivers/block/nvme.c
@@ -80,6 +80,7 @@ struct nvme_dev {
         char model[40];
         char firmware_rev[8];
         u32 max_hw_sectors;
+        u16 oncs;
 };
 
 /*
@@ -510,6 +511,44 @@ static int nvme_map_bio(struct device *dev, struct nvme_iod *iod,
         return length;
 }
 
+/*
+ * 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_submit_discard(struct nvme_queue *nvmeq, struct nvme_ns *ns,
+                struct bio *bio, struct nvme_iod *iod, int cmdid)
+{
+        struct nvme_dsm_range *range;
+        struct nvme_command *cmnd = &nvmeq->sq_cmds[nvmeq->sq_tail];
+
+        range = dma_pool_alloc(nvmeq->dev->prp_small_pool, GFP_ATOMIC,
+                                                        &iod->first_dma);
+        if (!range)
+                return -ENOMEM;
+
+        iod_list(iod)[0] = (__le64 *)range;
+        iod->npages = 0;
+
+        range->cattr = cpu_to_le32(0);
+        range->nlb = cpu_to_le32(bio->bi_size >> ns->lba_shift);
+        range->slba = cpu_to_le64(bio->bi_sector >> (ns->lba_shift - 9));
+
+        memset(cmnd, 0, sizeof(*cmnd));
+        cmnd->dsm.opcode = nvme_cmd_dsm;
+        cmnd->dsm.command_id = cmdid;
+        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);
+
+        if (++nvmeq->sq_tail == nvmeq->q_depth)
+                nvmeq->sq_tail = 0;
+        writel(nvmeq->sq_tail, nvmeq->q_db);
+
+        return 0;
+}
+
 static int nvme_submit_flush(struct nvme_queue *nvmeq, struct nvme_ns *ns,
                                                                 int cmdid)
 {
@@ -567,6 +606,12 @@ static int nvme_submit_bio_queue(struct nvme_queue *nvmeq, struct nvme_ns *ns,
         if (unlikely(cmdid < 0))
                 goto free_iod;
 
+        if (bio->bi_rw & REQ_DISCARD) {
+                result = nvme_submit_discard(nvmeq, ns, bio, iod, cmdid);
+                if (result)
+                        goto free_cmdid;
+                return result;
+        }
         if ((bio->bi_rw & REQ_FLUSH) && !psegs)
                 return nvme_submit_flush(nvmeq, ns, cmdid);
 
@@ -1347,6 +1392,16 @@ static void nvme_put_ns_idx(int index)
         spin_unlock(&dev_list_lock);
 }
 
+static void nvme_config_discard(struct nvme_ns *ns)
+{
+        u32 logical_block_size = queue_logical_block_size(ns->queue);
+        ns->queue->limits.discard_zeroes_data = 0;
+        ns->queue->limits.discard_alignment = logical_block_size;
+        ns->queue->limits.discard_granularity = logical_block_size;
+        ns->queue->limits.max_discard_sectors = 0xffffffff;
+        queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, ns->queue);
+}
+
 static struct nvme_ns *nvme_alloc_ns(struct nvme_dev *dev, int nsid,
                         struct nvme_id_ns *id, struct nvme_lba_range_type *rt)
 {
@@ -1366,7 +1421,6 @@ static struct nvme_ns *nvme_alloc_ns(struct nvme_dev *dev, int nsid,
         ns->queue->queue_flags = QUEUE_FLAG_DEFAULT;
         queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES, ns->queue);
         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, ns->queue);
-/*      queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, ns->queue); */
         blk_queue_make_request(ns->queue, nvme_make_request);
         ns->dev = dev;
         ns->queue->queuedata = ns;
@@ -1392,6 +1446,9 @@ static struct nvme_ns *nvme_alloc_ns(struct nvme_dev *dev, int nsid,
         sprintf(disk->disk_name, "nvme%dn%d", dev->instance, nsid);
         set_capacity(disk, le64_to_cpup(&id->nsze) << (ns->lba_shift - 9));
 
+        if (dev->oncs & NVME_CTRL_ONCS_DSM)
+                nvme_config_discard(ns);
+
         return ns;
 
  out_free_queue:
@@ -1520,6 +1577,7 @@ static int nvme_dev_add(struct nvme_dev *dev)
 
         ctrl = mem;
         nn = le32_to_cpup(&ctrl->nn);
+        dev->oncs = le16_to_cpup(&ctrl->oncs);
         memcpy(dev->serial, ctrl->sn, sizeof(ctrl->sn));
         memcpy(dev->model, ctrl->mn, sizeof(ctrl->mn));
         memcpy(dev->firmware_rev, ctrl->fr, sizeof(ctrl->fr));