NVMe: Retry failed commands with non-fatal errors

For commands returned with failed status, queue these for resubmission
and continue retrying them until success or for a limited amount of
time. The final timeout was arbitrarily chosen so requests can't be
retried indefinitely.

Since these are requeued on the nvmeq that submitted the command, the
callbacks have to take an nvmeq instead of an nvme_dev as a parameter
so that we can use the locked queue to append the iod to retry later.

The nvme_iod conviently can be used to track how long we've been trying
to successfully complete an iod request. The nvme_iod also provides the
nvme prp dma mappings, so I had to move a few things around so we can
keep those mappings.
Signed-off-by: Keith Busch <keith.busch@intel.com>
[fixed checkpatch issue with long line]
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

drivers/block/nvme-scsi.c

@@ -1562,13 +1562,14 @@ static int nvme_trans_send_fw_cmd(struct nvme_ns *ns, struct sg_io_hdr *hdr,
 			res = PTR_ERR(iod);
 			goto out;
 		}
-		length = nvme_setup_prps(dev, &c.common, iod, tot_len,
-								GFP_KERNEL);
+		length = nvme_setup_prps(dev, iod, tot_len, GFP_KERNEL);
 		if (length != tot_len) {
 			res = -ENOMEM;
 			goto out_unmap;
 		}
 
+		c.dlfw.prp1 = cpu_to_le64(sg_dma_address(iod->sg));
+		c.dlfw.prp2 = cpu_to_le64(iod->first_dma);
 		c.dlfw.numd = cpu_to_le32((tot_len/BYTES_TO_DWORDS) - 1);
 		c.dlfw.offset = cpu_to_le32(offset/BYTES_TO_DWORDS);
 	} else if (opcode == nvme_admin_activate_fw) {
@@ -2092,8 +2093,7 @@ static int nvme_trans_do_nvme_io(struct nvme_ns *ns, struct sg_io_hdr *hdr,
 			res = PTR_ERR(iod);
 			goto out;
 		}
-		retcode = nvme_setup_prps(dev, &c.common, iod, unit_len,
-							GFP_KERNEL);
+		retcode = nvme_setup_prps(dev, iod, unit_len, GFP_KERNEL);
 		if (retcode != unit_len) {
 			nvme_unmap_user_pages(dev,
 				(is_write) ? DMA_TO_DEVICE : DMA_FROM_DEVICE,
@@ -2102,6 +2102,8 @@ static int nvme_trans_do_nvme_io(struct nvme_ns *ns, struct sg_io_hdr *hdr,
 			res = -ENOMEM;
 			goto out;
 		}
+		c.rw.prp1 = cpu_to_le64(sg_dma_address(iod->sg));
+		c.rw.prp2 = cpu_to_le64(iod->first_dma);
 
 		nvme_offset += unit_num_blocks;
 

include/linux/nvme.h

@@ -136,6 +136,7 @@ struct nvme_iod {
 	int length;		/* Of data, in bytes */
 	unsigned long start_time;
 	dma_addr_t first_dma;
+	struct list_head node;
 	struct scatterlist sg[0];
 };
 
@@ -151,8 +152,7 @@ static inline u64 nvme_block_nr(struct nvme_ns *ns, sector_t sector)
  */
 void nvme_free_iod(struct nvme_dev *dev, struct nvme_iod *iod);
 
-int nvme_setup_prps(struct nvme_dev *dev, struct nvme_common_command *cmd,
-			struct nvme_iod *iod, int total_len, gfp_t gfp);
+int nvme_setup_prps(struct nvme_dev *, struct nvme_iod *, int , gfp_t);
 struct nvme_iod *nvme_map_user_pages(struct nvme_dev *dev, int write,
 				unsigned long addr, unsigned length);
 void nvme_unmap_user_pages(struct nvme_dev *dev, int write,

include/uapi/linux/nvme.h

@@ -434,6 +434,7 @@ enum {
 	NVME_SC_REFTAG_CHECK		= 0x284,
 	NVME_SC_COMPARE_FAILED		= 0x285,
 	NVME_SC_ACCESS_DENIED		= 0x286,
+	NVME_SC_DNR			= 0x4000,
 };
 
 struct nvme_completion {