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, 21 insertions, 16 deletions

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 8273b078686d..6ff94a948a4b 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -1184,9 +1184,10 @@ static void mmc_blk_issue_discard_rq(struct mmc_queue *mq, struct request *req)
 	struct mmc_card *card = md->queue.card;
 	unsigned int from, nr, arg;
 	int err = 0, type = MMC_BLK_DISCARD;
+	blk_status_t status = BLK_STS_OK;
 
 	if (!mmc_can_erase(card)) {
-		err = -EOPNOTSUPP;
+		status = BLK_STS_NOTSUPP;
 		goto fail;
 	}
 
@@ -1212,10 +1213,12 @@ static void mmc_blk_issue_discard_rq(struct mmc_queue *mq, struct request *req)
 		if (!err)
 			err = mmc_erase(card, from, nr, arg);
 	} while (err == -EIO && !mmc_blk_reset(md, card->host, type));
-	if (!err)
+	if (err)
+		status = BLK_STS_IOERR;
+	else
 		mmc_blk_reset_success(md, type);
 fail:
-	blk_end_request(req, err, blk_rq_bytes(req));
+	blk_end_request(req, status, blk_rq_bytes(req));
 }
 
 static void mmc_blk_issue_secdiscard_rq(struct mmc_queue *mq,
@@ -1225,9 +1228,10 @@ static void mmc_blk_issue_secdiscard_rq(struct mmc_queue *mq,
 	struct mmc_card *card = md->queue.card;
 	unsigned int from, nr, arg;
 	int err = 0, type = MMC_BLK_SECDISCARD;
+	blk_status_t status = BLK_STS_OK;
 
 	if (!(mmc_can_secure_erase_trim(card))) {
-		err = -EOPNOTSUPP;
+		status = BLK_STS_NOTSUPP;
 		goto out;
 	}
 
@@ -1254,8 +1258,10 @@ retry:
 	err = mmc_erase(card, from, nr, arg);
 	if (err == -EIO)
 		goto out_retry;
-	if (err)
+	if (err) {
+		status = BLK_STS_IOERR;
 		goto out;
+	}
 
 	if (arg == MMC_SECURE_TRIM1_ARG) {
 		if (card->quirks & MMC_QUIRK_INAND_CMD38) {
@@ -1270,8 +1276,10 @@ retry:
 		err = mmc_erase(card, from, nr, MMC_SECURE_TRIM2_ARG);
 		if (err == -EIO)
 			goto out_retry;
-		if (err)
+		if (err) {
+			status = BLK_STS_IOERR;
 			goto out;
+		}
 	}
 
 out_retry:
@@ -1280,7 +1288,7 @@ out_retry:
 	if (!err)
 		mmc_blk_reset_success(md, type);
 out:
-	blk_end_request(req, err, blk_rq_bytes(req));
+	blk_end_request(req, status, blk_rq_bytes(req));
 }
 
 static void mmc_blk_issue_flush(struct mmc_queue *mq, struct request *req)
@@ -1290,10 +1298,7 @@ static void mmc_blk_issue_flush(struct mmc_queue *mq, struct request *req)
 	int ret = 0;
 
 	ret = mmc_flush_cache(card);
-	if (ret)
-		ret = -EIO;
-
-	blk_end_request_all(req, ret);
+	blk_end_request_all(req, ret ? BLK_STS_IOERR : BLK_STS_OK);
 }
 
 /*
@@ -1641,7 +1646,7 @@ static void mmc_blk_rw_cmd_abort(struct mmc_queue *mq, struct mmc_card *card,
 {
 	if (mmc_card_removed(card))
 		req->rq_flags |= RQF_QUIET;
-	while (blk_end_request(req, -EIO, blk_rq_cur_bytes(req)));
+	while (blk_end_request(req, BLK_STS_IOERR, blk_rq_cur_bytes(req)));
 	mmc_queue_req_free(mq, mqrq);
 }
 
@@ -1661,7 +1666,7 @@ static void mmc_blk_rw_try_restart(struct mmc_queue *mq, struct request *req,
 	 */
 	if (mmc_card_removed(mq->card)) {
 		req->rq_flags |= RQF_QUIET;
-		blk_end_request_all(req, -EIO);
+		blk_end_request_all(req, BLK_STS_IOERR);
 		mmc_queue_req_free(mq, mqrq);
 		return;
 	}
@@ -1743,7 +1748,7 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
 			 */
 			mmc_blk_reset_success(md, type);
 
-			req_pending = blk_end_request(old_req, 0,
+			req_pending = blk_end_request(old_req, BLK_STS_OK,
 						      brq->data.bytes_xfered);
 			/*
 			 * If the blk_end_request function returns non-zero even
@@ -1811,7 +1816,7 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
 			 * time, so we only reach here after trying to
 			 * read a single sector.
 			 */
-			req_pending = blk_end_request(old_req, -EIO,
+			req_pending = blk_end_request(old_req, BLK_STS_IOERR,
 						      brq->data.blksz);
 			if (!req_pending) {
 				mmc_queue_req_free(mq, mq_rq);
@@ -1860,7 +1865,7 @@ void mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 	ret = mmc_blk_part_switch(card, md);
 	if (ret) {
 		if (req) {
-			blk_end_request_all(req, -EIO);
+			blk_end_request_all(req, BLK_STS_IOERR);
 		}
 		goto out;
 	}