[PATCH v2 1/3] Call scsi_initialize_rq() also for filesystem requests

[Bart Van Assche <bart.vanassche@xxxxxxx>]

If a pass-through request is submitted then blk_get_request()
initializes that request by calling scsi_initialize_rq(). Also
call this function for filesystem requests. Introduce
CMD_INITIALIZED to keep track of whether or not a request has
already been initialized.

Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Johannes Thumshirn <jthumshirn@xxxxxxx>
---
 drivers/scsi/scsi_lib.c  | 28 ++++++++++++++++++++++++----
 include/scsi/scsi_cmnd.h |  3 +++
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 938a7e398cd4..170a725e33ce 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -642,6 +642,11 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
 	if (blk_queue_add_random(q))
 		add_disk_randomness(req->rq_disk);
 
+	if (!blk_rq_is_scsi(req)) {
+		WARN_ON_ONCE(!(cmd->flags & SCMD_INITIALIZED));
+		cmd->flags &= ~SCMD_INITIALIZED;
+	}
+
 	if (req->mq_ctx) {
 		/*
 		 * In the MQ case the command gets freed by __blk_mq_end_request,
@@ -1110,7 +1115,8 @@ EXPORT_SYMBOL(scsi_init_io);
  * scsi_initialize_rq - initialize struct scsi_cmnd.req
  * @rq: Request associated with the SCSI command to be initialized.
  *
- * Called from inside blk_get_request().
+ * Called from inside blk_get_request() for pass-through requests and from
+ * inside scsi_init_command() for filesystem requests.
  */
 void scsi_initialize_rq(struct request *rq)
 {
@@ -1154,7 +1160,13 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
 {
 	void *buf = cmd->sense_buffer;
 	void *prot = cmd->prot_sdb;
-	unsigned int unchecked_isa_dma = cmd->flags & SCMD_UNCHECKED_ISA_DMA;
+	struct request *rq = blk_mq_rq_from_pdu(cmd);
+	unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS;
+
+	if (!blk_rq_is_scsi(rq) && !(flags & SCMD_INITIALIZED)) {
+		flags |= SCMD_INITIALIZED;
+		scsi_initialize_rq(rq);
+	}
 
 	/* zero out the cmd, except for the embedded scsi_request */
 	memset((char *)cmd + sizeof(cmd->req), 0,
@@ -1163,7 +1175,7 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
 	cmd->device = dev;
 	cmd->sense_buffer = buf;
 	cmd->prot_sdb = prot;
-	cmd->flags = unchecked_isa_dma;
+	cmd->flags = flags;
 	INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
 	cmd->jiffies_at_alloc = jiffies;
 
@@ -1350,6 +1362,8 @@ static int scsi_prep_fn(struct request_queue *q, struct request *req)
 
 	ret = scsi_setup_cmnd(sdev, req);
 out:
+	if (ret != BLKPREP_OK)
+		cmd->flags &= ~SCMD_INITIALIZED;
 	return scsi_prep_return(q, req, ret);
 }
 
@@ -1869,6 +1883,7 @@ static int scsi_mq_prep_fn(struct request *req)
 	struct scsi_device *sdev = req->q->queuedata;
 	struct Scsi_Host *shost = sdev->host;
 	struct scatterlist *sg;
+	int ret;
 
 	scsi_init_command(sdev, cmd);
 
@@ -1902,7 +1917,10 @@ static int scsi_mq_prep_fn(struct request *req)
 
 	blk_mq_start_request(req);
 
-	return scsi_setup_cmnd(sdev, req);
+	ret = scsi_setup_cmnd(sdev, req);
+	if (ret != BLK_STS_OK)
+		cmd->flags &= ~SCMD_INITIALIZED;
+	return ret;
 }
 
 static void scsi_mq_done(struct scsi_cmnd *cmd)
@@ -1938,6 +1956,8 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
 		goto out_dec_target_busy;
 
 	if (!(req->rq_flags & RQF_DONTPREP)) {
+		if (!blk_rq_is_scsi(req))
+			WARN_ON_ONCE(cmd->flags & SCMD_INITIALIZED);
 		ret = prep_to_mq(scsi_mq_prep_fn(req));
 		if (ret != BLK_STS_OK)
 			goto out_dec_host_busy;
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index f5afcff8d76f..a9f8f7e79d83 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -57,6 +57,9 @@ struct scsi_pointer {
 /* for scmd->flags */
 #define SCMD_TAGGED		(1 << 0)
 #define SCMD_UNCHECKED_ISA_DMA	(1 << 1)
+#define SCMD_INITIALIZED	(1 << 3)
+/* flags preserved across unprep / reprep */
+#define SCMD_PRESERVED_FLAGS	(SCMD_UNCHECKED_ISA_DMA | SCMD_INITIALIZED)
 
 struct scsi_cmnd {
 	struct scsi_request req;
-- 
2.14.1