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, 4 insertions, 4 deletions

diff --git a/drivers/block/xsysace.c b/drivers/block/xsysace.c
index 757dce2..977fdf0 100644
--- a/drivers/block/xsysace.c
+++ b/drivers/block/xsysace.c
@@ -471,7 +471,7 @@ static struct request *ace_get_next_request(struct request_queue *q)
 		if (!blk_rq_is_passthrough(req))
 			break;
 		blk_start_request(req);
-		__blk_end_request_all(req, -EIO);
+		__blk_end_request_all(req, BLK_STS_IOERR);
 	}
 	return req;
 }
@@ -499,11 +499,11 @@ static void ace_fsm_dostate(struct ace_device *ace)
 
 		/* Drop all in-flight and pending requests */
 		if (ace->req) {
-			__blk_end_request_all(ace->req, -EIO);
+			__blk_end_request_all(ace->req, BLK_STS_IOERR);
 			ace->req = NULL;
 		}
 		while ((req = blk_fetch_request(ace->queue)) != NULL)
-			__blk_end_request_all(req, -EIO);
+			__blk_end_request_all(req, BLK_STS_IOERR);
 
 		/* Drop back to IDLE state and notify waiters */
 		ace->fsm_state = ACE_FSM_STATE_IDLE;
@@ -728,7 +728,7 @@ static void ace_fsm_dostate(struct ace_device *ace)
 		}
 
 		/* bio finished; is there another one? */
-		if (__blk_end_request_cur(ace->req, 0)) {
+		if (__blk_end_request_cur(ace->req, BLK_STS_OK)) {
 			/* dev_dbg(ace->dev, "next block; h=%u c=%u\n",
 			 *      blk_rq_sectors(ace->req),
 			 *      blk_rq_cur_sectors(ace->req));