Re: [PATCH v2 02/50] core: Use scsi_cmd_to_rq() instead of scsi_cmnd.request

Douglas Gilbert <dgilbert@xxxxxxxxxxxx> · Tue, 18 May 2021 16:01:27 -0400

On 2021-05-18 1:44 p.m., Bart Van Assche wrote:
Prepare for removal of the request pointer by using scsi_cmd_to_rq()
instead. This patch does not change any functionality.

Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
  drivers/scsi/scsi.c         |  2 +-
  drivers/scsi/scsi_error.c   | 14 +++++++-------
  drivers/scsi/scsi_lib.c     | 28 +++++++++++++++-------------
  drivers/scsi/scsi_logging.c | 18 ++++++++++--------
  include/scsi/scsi_cmnd.h    |  6 ++++--
  include/scsi/scsi_device.h  | 16 +++++++++-------
  6 files changed, 46 insertions(+), 38 deletions(-)

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index e9e2f0e15ac8..7d545223dd59 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -197,7 +197,7 @@ void scsi_finish_command(struct scsi_cmnd *cmd)
  				"(result %x)\n", cmd->result));
  
  	good_bytes = scsi_bufflen(cmd);
-	if (!blk_rq_is_passthrough(cmd->request)) {
+	if (!blk_rq_is_passthrough(scsi_cmd_to_rq(cmd))) {
  		int old_good_bytes = good_bytes;
  		drv = scsi_cmd_to_driver(cmd);
  		if (drv->done)
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index d8fafe77dbbe..5af6d87e83aa 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -242,7 +242,7 @@ scsi_abort_command(struct scsi_cmnd *scmd)
   */
  static void scsi_eh_reset(struct scsi_cmnd *scmd)
  {
-	if (!blk_rq_is_passthrough(scmd->request)) {
+	if (!blk_rq_is_passthrough(scsi_cmd_to_rq(scmd))) {
  		struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
  		if (sdrv->eh_reset)
  			sdrv->eh_reset(scmd);
@@ -1188,7 +1188,7 @@ static enum scsi_disposition scsi_request_sense(struct scsi_cmnd *scmd)
  static enum scsi_disposition
  scsi_eh_action(struct scsi_cmnd *scmd, enum scsi_disposition rtn)
  {
-	if (!blk_rq_is_passthrough(scmd->request)) {
+	if (!blk_rq_is_passthrough(scsi_cmd_to_rq(scmd))) {
  		struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
  		if (sdrv->eh_action)
  			rtn = sdrv->eh_action(scmd, rtn);
@@ -1762,16 +1762,16 @@ int scsi_noretry_cmd(struct scsi_cmnd *scmd)
  	case DID_TIME_OUT:
  		goto check_type;
  	case DID_BUS_BUSY:
-		return (scmd->request->cmd_flags & REQ_FAILFAST_TRANSPORT);
+		return scsi_cmd_to_rq(scmd)->cmd_flags & REQ_FAILFAST_TRANSPORT;
  	case DID_PARITY:
-		return (scmd->request->cmd_flags & REQ_FAILFAST_DEV);
+		return scsi_cmd_to_rq(scmd)->cmd_flags & REQ_FAILFAST_DEV;
  	case DID_ERROR:
  		if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
  		    status_byte(scmd->result) == RESERVATION_CONFLICT)
  			return 0;
  		fallthrough;
  	case DID_SOFT_ERROR:
-		return (scmd->request->cmd_flags & REQ_FAILFAST_DRIVER);
+		return scsi_cmd_to_rq(scmd)->cmd_flags & REQ_FAILFAST_DRIVER;
  	}
  
  	if (status_byte(scmd->result) != CHECK_CONDITION)
@@ -1782,8 +1782,8 @@ int scsi_noretry_cmd(struct scsi_cmnd *scmd)
  	 * assume caller has checked sense and determined
  	 * the check condition was retryable.
  	 */
-	if (scmd->request->cmd_flags & REQ_FAILFAST_DEV ||
-	    blk_rq_is_passthrough(scmd->request))
+	if (scsi_cmd_to_rq(scmd)->cmd_flags & REQ_FAILFAST_DEV ||
+	    blk_rq_is_passthrough(scsi_cmd_to_rq(scmd)))
  		return 1;
  
  	return 0;
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 532304d42f00..2e9598c91cee 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -119,13 +119,15 @@ scsi_set_blocked(struct scsi_cmnd *cmd, int reason)
  
  static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd)
  {
-	if (cmd->request->rq_flags & RQF_DONTPREP) {
-		cmd->request->rq_flags &= ~RQF_DONTPREP;
+	struct request *rq = scsi_cmd_to_rq(cmd);
+
+	if (rq->rq_flags & RQF_DONTPREP) {
+		rq->rq_flags &= ~RQF_DONTPREP;
  		scsi_mq_uninit_cmd(cmd);
  	} else {
  		WARN_ON_ONCE(true);
  	}
-	blk_mq_requeue_request(cmd->request, true);
+	blk_mq_requeue_request(rq, true);
  }
  
  /**
@@ -164,7 +166,7 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, bool unbusy)
  	 */
  	cmd->result = 0;
  
-	blk_mq_requeue_request(cmd->request, true);
+	blk_mq_requeue_request(scsi_cmd_to_rq(cmd), true);
  }
  
  /**
@@ -475,7 +477,7 @@ void scsi_run_host_queues(struct Scsi_Host *shost)
  
  static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
  {
-	if (!blk_rq_is_passthrough(cmd->request)) {
+	if (!blk_rq_is_passthrough(scsi_cmd_to_rq(cmd))) {
  		struct scsi_driver *drv = scsi_cmd_to_driver(cmd);
  
  		if (drv->uninit_command)
@@ -626,7 +628,7 @@ static void scsi_io_completion_reprep(struct scsi_cmnd *cmd,
  
  static bool scsi_cmd_runtime_exceeced(struct scsi_cmnd *cmd)
  {
-	struct request *req = cmd->request;
+	struct request *req = scsi_cmd_to_rq(cmd);
  	unsigned long wait_for;
  
  	if (cmd->allowed == SCSI_CMD_RETRIES_NO_LIMIT)
@@ -645,7 +647,7 @@ static bool scsi_cmd_runtime_exceeced(struct scsi_cmnd *cmd)
  static void scsi_io_completion_action(struct scsi_cmnd *cmd, int result)
  {
  	struct request_queue *q = cmd->device->request_queue;
-	struct request *req = cmd->request;
+	struct request *req = scsi_cmd_to_rq(cmd);
  	int level = 0;
  	enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
  	      ACTION_DELAYED_RETRY} action;
@@ -819,7 +821,7 @@ static int scsi_io_completion_nz_result(struct scsi_cmnd *cmd, int result,
  {
  	bool sense_valid;
  	bool sense_current = true;	/* false implies "deferred sense" */
-	struct request *req = cmd->request;
+	struct request *req = scsi_cmd_to_rq(cmd);
  	struct scsi_sense_hdr sshdr;
  
  	sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
@@ -908,7 +910,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
  {
  	int result = cmd->result;
  	struct request_queue *q = cmd->device->request_queue;
-	struct request *req = cmd->request;
+	struct request *req = scsi_cmd_to_rq(cmd);
  	blk_status_t blk_stat = BLK_STS_OK;
  
  	if (unlikely(result))	/* a nz result may or may not be an error */
@@ -979,7 +981,7 @@ static inline bool scsi_cmd_needs_dma_drain(struct scsi_device *sdev,
  blk_status_t scsi_alloc_sgtables(struct scsi_cmnd *cmd)
  {
  	struct scsi_device *sdev = cmd->device;
-	struct request *rq = cmd->request;
+	struct request *rq = scsi_cmd_to_rq(cmd);
  	unsigned short nr_segs = blk_rq_nr_phys_segments(rq);
  	struct scatterlist *last_sg = NULL;
  	blk_status_t ret;
@@ -1108,7 +1110,7 @@ void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
  {
  	void *buf = cmd->sense_buffer;
  	void *prot = cmd->prot_sdb;
-	struct request *rq = blk_mq_rq_from_pdu(cmd);
+	struct request *rq = scsi_cmd_to_rq(cmd);
  	unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS;
  	unsigned long jiffies_at_alloc;
  	int retries, to_clear;
@@ -1573,12 +1575,12 @@ static blk_status_t scsi_prepare_cmd(struct request *req)
  
  static void scsi_mq_done(struct scsi_cmnd *cmd)
  {
-	if (unlikely(blk_should_fake_timeout(cmd->request->q)))
+	if (unlikely(blk_should_fake_timeout(scsi_cmd_to_rq(cmd)->q)))
  		return;
  	if (unlikely(test_and_set_bit(SCMD_STATE_COMPLETE, &cmd->state)))
  		return;
  	trace_scsi_dispatch_cmd_done(cmd);
-	blk_mq_complete_request(cmd->request);
+	blk_mq_complete_request(scsi_cmd_to_rq(cmd));
  }
  
  static void scsi_mq_put_budget(struct request_queue *q, int budget_token)
diff --git a/drivers/scsi/scsi_logging.c b/drivers/scsi/scsi_logging.c
index 8ea44c6595ef..f0ae55ad0973 100644
--- a/drivers/scsi/scsi_logging.c
+++ b/drivers/scsi/scsi_logging.c
@@ -28,8 +28,9 @@ static void scsi_log_release_buffer(char *bufptr)
  
  static inline const char *scmd_name(const struct scsi_cmnd *scmd)
  {
-	return scmd->request->rq_disk ?
-		scmd->request->rq_disk->disk_name : NULL;
+	struct request *rq = scsi_cmd_to_rq((struct scsi_cmnd *)scmd);
+
+	return rq->rq_disk ? rq->rq_disk->disk_name : NULL;
  }
  
  static size_t sdev_format_header(char *logbuf, size_t logbuf_len,
@@ -91,7 +92,7 @@ void scmd_printk(const char *level, const struct scsi_cmnd *scmd,
  	if (!logbuf)
  		return;
  	off = sdev_format_header(logbuf, logbuf_len, scmd_name(scmd),
-				 scmd->request->tag);
+				 scsi_cmd_to_rq((struct scsi_cmnd *)scmd)->tag);
  	if (off < logbuf_len) {
  		va_start(args, fmt);
  		off += vscnprintf(logbuf + off, logbuf_len - off, fmt, args);
@@ -188,7 +189,7 @@ void scsi_print_command(struct scsi_cmnd *cmd)
  		return;
  
  	off = sdev_format_header(logbuf, logbuf_len,
-				 scmd_name(cmd), cmd->request->tag);
+				 scmd_name(cmd), scsi_cmd_to_rq(cmd)->tag);
  	if (off >= logbuf_len)
  		goto out_printk;
  	off += scnprintf(logbuf + off, logbuf_len - off, "CDB: ");
@@ -210,7 +211,7 @@ void scsi_print_command(struct scsi_cmnd *cmd)
  
  			off = sdev_format_header(logbuf, logbuf_len,
  						 scmd_name(cmd),
-						 cmd->request->tag);
+						 scsi_cmd_to_rq(cmd)->tag);
  			if (!WARN_ON(off > logbuf_len - 58)) {
  				off += scnprintf(logbuf + off, logbuf_len - off,
  						 "CDB[%02x]: ", k);
@@ -373,7 +374,8 @@ EXPORT_SYMBOL(__scsi_print_sense);
  /* Normalize and print sense buffer in SCSI command */
  void scsi_print_sense(const struct scsi_cmnd *cmd)
  {
-	scsi_log_print_sense(cmd->device, scmd_name(cmd), cmd->request->tag,
+	scsi_log_print_sense(cmd->device, scmd_name(cmd),
+			     scsi_cmd_to_rq((struct scsi_cmnd *)cmd)->tag,
  			     cmd->sense_buffer, SCSI_SENSE_BUFFERSIZE);
  }
  EXPORT_SYMBOL(scsi_print_sense);
@@ -392,8 +394,8 @@ void scsi_print_result(const struct scsi_cmnd *cmd, const char *msg,
  	if (!logbuf)
  		return;
  
-	off = sdev_format_header(logbuf, logbuf_len,
-				 scmd_name(cmd), cmd->request->tag);
+	off = sdev_format_header(logbuf, logbuf_len, scmd_name(cmd),
+				 scsi_cmd_to_rq((struct scsi_cmnd *)cmd)->tag);
  
  	if (off >= logbuf_len)
  		goto out_printk;
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 6787670d0d16..bd7f73f035be 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -164,7 +164,9 @@ static inline void *scsi_cmd_priv(struct scsi_cmnd *cmd)
  /* make sure not to use it with passthrough commands */
  static inline struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
  {
-	return *(struct scsi_driver **)cmd->request->rq_disk->private_data;
+	struct request *rq = scsi_cmd_to_rq(cmd);
+
+	return *(struct scsi_driver **)rq->rq_disk->private_data;
  }
  
  extern void scsi_finish_command(struct scsi_cmnd *cmd);
@@ -290,7 +292,7 @@ static inline unsigned char scsi_get_prot_type(struct scsi_cmnd *scmd)
  
  static inline sector_t scsi_get_lba(struct scsi_cmnd *scmd)
  {
-	return blk_rq_pos(scmd->request);
+	return blk_rq_pos(scsi_cmd_to_rq(scmd));
  }
  
  static inline unsigned int scsi_prot_interval(struct scsi_cmnd *scmd)
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index ac6ab16abee7..09797a2b779d 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -265,13 +265,15 @@ sdev_prefix_printk(const char *, const struct scsi_device *, const char *,
  __printf(3, 4) void
  scmd_printk(const char *, const struct scsi_cmnd *, const char *, ...);
  
-#define scmd_dbg(scmd, fmt, a...)					   \
-	do {								   \
-		if ((scmd)->request->rq_disk)				   \
-			sdev_dbg((scmd)->device, "[%s] " fmt,		   \
-				 (scmd)->request->rq_disk->disk_name, ##a);\
-		else							   \
-			sdev_dbg((scmd)->device, fmt, ##a);		   \
+#define scmd_dbg(scmd, fmt, a...)				\
+	do {							\
+		struct request *rq = scsi_cmd_to_rq((scmd));	\

When introducing a new name (e.g. rq) in a macro, shouldn't it be prefixed
with either a single or double underscore? There is a good chance rq maybe
in use in the enclosing scope causing a compiler warning.

+								\
+		if (rq->rq_disk)				\
+			sdev_dbg((scmd)->device, "[%s] " fmt,	\
+				 rq->rq_disk->disk_name, ##a);	\
+		else						\
+			sdev_dbg((scmd)->device, fmt, ##a);	\
  	} while (0)
  
  enum scsi_target_state {


To James's point, using fio (or dd, sg_dd, etc) and scsi_debug as the LLD
in before and after runs might show a performance improvement.






