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, 3 insertions, 3 deletions

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 82c33a6edbea..f3387c6089c5 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -177,7 +177,7 @@ typedef struct sg_device { /* holds the state of each scsi generic device */
 } Sg_device;
 
 /* tasklet or soft irq callback */
-static void sg_rq_end_io(struct request *rq, int uptodate);
+static void sg_rq_end_io(struct request *rq, blk_status_t status);
 static int sg_start_req(Sg_request *srp, unsigned char *cmd);
 static int sg_finish_rem_req(Sg_request * srp);
 static int sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size);
@@ -808,7 +808,7 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
 	if (atomic_read(&sdp->detaching)) {
 		if (srp->bio) {
 			scsi_req_free_cmd(scsi_req(srp->rq));
-			blk_end_request_all(srp->rq, -EIO);
+			blk_end_request_all(srp->rq, BLK_STS_IOERR);
 			srp->rq = NULL;
 		}
 
@@ -1300,7 +1300,7 @@ sg_rq_end_io_usercontext(struct work_struct *work)
  * level when a command is completed (or has failed).
  */
 static void
-sg_rq_end_io(struct request *rq, int uptodate)
+sg_rq_end_io(struct request *rq, blk_status_t status)
 {
 	struct sg_request *srp = rq->end_io_data;
 	struct scsi_request *req = scsi_req(rq);