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>

2 files changed, 9 insertions, 6 deletions

diff --git a/drivers/memstick/core/ms_block.c b/drivers/memstick/core/ms_block.c
index 99e651c27fb7..22de7f5ed032 100644
--- a/drivers/memstick/core/ms_block.c
+++ b/drivers/memstick/core/ms_block.c
@@ -1921,12 +1921,13 @@ static void msb_io_work(struct work_struct *work)
 		spin_lock_irqsave(&msb->q_lock, flags);
 
 		if (len)
-			if (!__blk_end_request(msb->req, 0, len))
+			if (!__blk_end_request(msb->req, BLK_STS_OK, len))
 				msb->req = NULL;
 
 		if (error && msb->req) {
+			blk_status_t ret = errno_to_blk_status(error);
 			dbg_verbose("IO: ending one sector of the request with error");
-			if (!__blk_end_request(msb->req, error, msb->page_size))
+			if (!__blk_end_request(msb->req, ret, msb->page_size))
 				msb->req = NULL;
 		}
 
@@ -2014,7 +2015,7 @@ static void msb_submit_req(struct request_queue *q)
 		WARN_ON(!msb->io_queue_stopped);
 
 		while ((req = blk_fetch_request(q)) != NULL)
-			__blk_end_request_all(req, -ENODEV);
+			__blk_end_request_all(req, BLK_STS_IOERR);
 		return;
 	}
 
diff --git a/drivers/memstick/core/mspro_block.c b/drivers/memstick/core/mspro_block.c
index c00d8a266878..8897962781bb 100644
--- a/drivers/memstick/core/mspro_block.c
+++ b/drivers/memstick/core/mspro_block.c
@@ -709,7 +709,8 @@ try_again:
 					       msb->req_sg);
 
 		if (!msb->seg_count) {
-			chunk = __blk_end_request_cur(msb->block_req, -ENOMEM);
+			chunk = __blk_end_request_cur(msb->block_req,
+					BLK_STS_RESOURCE);
 			continue;
 		}
 
@@ -776,7 +777,8 @@ static int mspro_block_complete_req(struct memstick_dev *card, int error)
 		if (error && !t_len)
 			t_len = blk_rq_cur_bytes(msb->block_req);
 
-		chunk = __blk_end_request(msb->block_req, error, t_len);
+		chunk = __blk_end_request(msb->block_req,
+				errno_to_blk_status(error), t_len);
 
 		error = mspro_block_issue_req(card, chunk);
 
@@ -838,7 +840,7 @@ static void mspro_block_submit_req(struct request_queue *q)
 
 	if (msb->eject) {
 		while ((req = blk_fetch_request(q)) != NULL)
-			__blk_end_request_all(req, -ENODEV);
+			__blk_end_request_all(req, BLK_STS_IOERR);
 
 		return;
 	}