block: introduce new block status code type

Currently we use nornal Linux errno values in the block layer, and while
we accept any error a few have overloaded magic meanings.  This patch
instead introduces a new  blk_status_t value that holds block layer specific
status codes and explicitly explains their meaning.  Helpers to convert from
and to the previous special meanings are provided for now, but I suspect
we want to get rid of them in the long run - those drivers that have a
errno input (e.g. networking) usually get errnos that don't know about
the special block layer overloads, and similarly returning them to userspace
will usually return somethings that strictly speaking isn't correct
for file system operations, but that's left as an exercise for later.

For now the set of errors is a very limited set that closely corresponds
to the previous overloaded errno values, but there is some low hanging
fruite to improve it.

blk_status_t (ab)uses the sparse __bitwise annotations to allow for sparse
typechecking, so that we can easily catch places passing the wrong values.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 11 insertions, 18 deletions

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index a60926410438..07e95c7d837a 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -70,29 +70,21 @@ static DEFINE_SPINLOCK(dev_list_lock);
 
 static struct class *nvme_class;
 
-static int nvme_error_status(struct request *req)
+static blk_status_t nvme_error_status(struct request *req)
 {
 	switch (nvme_req(req)->status & 0x7ff) {
 	case NVME_SC_SUCCESS:
-		return 0;
+		return BLK_STS_OK;
 	case NVME_SC_CAP_EXCEEDED:
-		return -ENOSPC;
-	default:
-		return -EIO;
-
-	/*
-	 * XXX: these errors are a nasty side-band protocol to
-	 * drivers/md/dm-mpath.c:noretry_error() that aren't documented
-	 * anywhere..
-	 */
-	case NVME_SC_CMD_SEQ_ERROR:
-		return -EILSEQ;
+		return BLK_STS_NOSPC;
 	case NVME_SC_ONCS_NOT_SUPPORTED:
-		return -EOPNOTSUPP;
+		return BLK_STS_NOTSUPP;
 	case NVME_SC_WRITE_FAULT:
 	case NVME_SC_READ_ERROR:
 	case NVME_SC_UNWRITTEN_BLOCK:
-		return -ENODATA;
+		return BLK_STS_MEDIUM;
+	default:
+		return BLK_STS_IOERR;
 	}
 }
 
@@ -555,15 +547,16 @@ int nvme_submit_user_cmd(struct request_queue *q, struct nvme_command *cmd,
 			result, timeout);
 }
 
-static void nvme_keep_alive_end_io(struct request *rq, int error)
+static void nvme_keep_alive_end_io(struct request *rq, blk_status_t status)
 {
 	struct nvme_ctrl *ctrl = rq->end_io_data;
 
 	blk_mq_free_request(rq);
 
-	if (error) {
+	if (status) {
 		dev_err(ctrl->device,
-			"failed nvme_keep_alive_end_io error=%d\n", error);
+			"failed nvme_keep_alive_end_io error=%d\n",
+				status);
 		return;
 	}