[PATCH v2 01/20] block: Add a flag for internal commands

[Bart Van Assche <bvanassche@xxxxxxx>]

From: Hannes Reinecke <hare@xxxxxxx>

Some drivers use a single tag space for requests submitted by the block
layer and driver-internal requests. Driver-internal requests will never
pass through the block layer but require a valid tag. This patch adds a
new request flag REQ_INTERNAL to mark such requests and a terminates any
such commands in blk_execute_rq_nowait() with a WARN_ON_ONCE() to signal
such an invalid usage.

Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: John Garry <john.garry@xxxxxxxxxx>
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
[ bvanassche: modified patch description ]
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
 block/blk-exec.c          | 5 +++++
 include/linux/blk-mq.h    | 5 +++++
 include/linux/blk_types.h | 2 ++
 3 files changed, 12 insertions(+)

diff --git a/block/blk-exec.c b/block/blk-exec.c
index 1b8b47f6e79b..27d2e3779c13 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -53,6 +53,11 @@ void blk_execute_rq_nowait(struct gendisk *bd_disk, struct request *rq,
 	rq->rq_disk = bd_disk;
 	rq->end_io = done;
 
+	if (WARN_ON_ONCE(blk_rq_is_internal(rq))) {
+		blk_mq_end_request(rq, BLK_STS_NOTSUPP);
+		return;
+	}
+
 	blk_account_io_start(rq);
 
 	/*
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 2949d9ac7484..3b42fcdf0c15 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -208,6 +208,11 @@ static inline bool blk_rq_is_passthrough(struct request *rq)
 	return blk_op_is_passthrough(req_op(rq));
 }
 
+static inline bool blk_rq_is_internal(struct request *rq)
+{
+	return rq->cmd_flags & REQ_INTERNAL;
+}
+
 static inline unsigned short req_get_ioprio(struct request *req)
 {
 	return req->ioprio;
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index fe065c394fff..1ae2365e02d1 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -411,6 +411,7 @@ enum req_flag_bits {
 	/* for driver use */
 	__REQ_DRV,
 	__REQ_SWAP,		/* swapping request. */
+	__REQ_INTERNAL,		/* driver-internal command */
 	__REQ_NR_BITS,		/* stops here */
 };
 
@@ -435,6 +436,7 @@ enum req_flag_bits {
 
 #define REQ_DRV			(1ULL << __REQ_DRV)
 #define REQ_SWAP		(1ULL << __REQ_SWAP)
+#define REQ_INTERNAL		(1ULL << __REQ_INTERNAL)
 
 #define REQ_FAILFAST_MASK \
 	(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)