[PATCH 3/5] nvme: lightnvm: return ppa completion status

[Matias Bjørling]

PPAs sent to device is separately acknowledge in a 64bit status
variable. The status is stored in DW0 and DW1 of the completion queue
entry. Store this status inside the nvm_rq for further processing.

This can later be used to implement retry techniques for failed writes
and reads.

Reviewed-by: Christoph Hellwig <h...@lst.de>
Signed-off-by: Matias Bjørling <m...@bjorling.me>
---
 drivers/nvme/host/lightnvm.c | 17 +++++++++++++++--
 include/linux/lightnvm.h     |  1 +
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c
index 42a01a9..9461dd6 100644
--- a/drivers/nvme/host/lightnvm.c
+++ b/drivers/nvme/host/lightnvm.c
@@ -146,6 +146,14 @@ struct nvme_nvm_command {
        };
 };
 
+struct nvme_nvm_completion {
+       __le64  result;         /* Used by LightNVM to return ppa completions */
+       __le16  sq_head;        /* how much of this queue may be reclaimed */
+       __le16  sq_id;          /* submission queue that generated this entry */
+       __u16   command_id;     /* of the command which completed */
+       __le16  status;         /* did the command fail, and if so, why? */
+};
+
 #define NVME_NVM_LP_MLC_PAIRS 886
 struct nvme_nvm_lp_mlc {
        __u16                   num_pairs;
@@ -507,6 +515,10 @@ static inline void nvme_nvm_rqtocmd(struct request *rq, 
struct nvm_rq *rqd,
 static void nvme_nvm_end_io(struct request *rq, int error)
 {
        struct nvm_rq *rqd = rq->end_io_data;
+       struct nvme_nvm_completion *cqe = rq->special;
+
+       if (cqe)
+               rqd->ppa_status = le64_to_cpu(cqe->result);
 
        nvm_end_io(rqd, error);
 
@@ -526,7 +538,8 @@ static int nvme_nvm_submit_io(struct nvm_dev *dev, struct 
nvm_rq *rqd)
        if (IS_ERR(rq))
                return -ENOMEM;
 
-       cmd = kzalloc(sizeof(struct nvme_nvm_command), GFP_KERNEL);
+       cmd = kzalloc(sizeof(struct nvme_nvm_command) +
+                               sizeof(struct nvme_nvm_completion), GFP_KERNEL);
        if (!cmd) {
                blk_mq_free_request(rq);
                return -ENOMEM;
@@ -545,7 +558,7 @@ static int nvme_nvm_submit_io(struct nvm_dev *dev, struct 
nvm_rq *rqd)
 
        rq->cmd = (unsigned char *)cmd;
        rq->cmd_len = sizeof(struct nvme_nvm_command);
-       rq->special = (void *)0;
+       rq->special = cmd + 1;
 
        rq->end_io_data = rqd;
 
diff --git a/include/linux/lightnvm.h b/include/linux/lightnvm.h
index e27161f..643bdf4 100644
--- a/include/linux/lightnvm.h
+++ b/include/linux/lightnvm.h
@@ -238,6 +238,7 @@ struct nvm_rq {
        uint16_t nr_pages;
        uint16_t flags;
 
+       u64 ppa_status; /* ppa media status */
        int error;
 };
 
-- 
2.1.4