block: cleanup tracing

A couple tweaks to the tracing code:

 - trace the request size for all requests
 - trace request sector and nr_sectors only for fs requests, enforced by
   helpers
 - drop SCSI CDB tracing - we have SCSI tracing for this and are going
   to me the CDB out of the generic struct request soon.

With this the tracing code stops to know about BLOCK_PC requests entirely,
it's just FS vs passthrough requests now, where the latter includes any
driver-private requests.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

include/linux/blktrace_api.h

@@ -110,16 +110,16 @@ struct compat_blk_user_trace_setup {
 
 #endif
 
-#if defined(CONFIG_EVENT_TRACING) && defined(CONFIG_BLOCK)
+extern void blk_fill_rwbs(char *rwbs, unsigned int op, int bytes);
 
-static inline int blk_cmd_buf_len(struct request *rq)
+static inline sector_t blk_rq_trace_sector(struct request *rq)
 {
-	return (rq->cmd_type == REQ_TYPE_BLOCK_PC) ? rq->cmd_len * 3 : 1;
+	return (rq->cmd_type != REQ_TYPE_FS) ? 0 : blk_rq_pos(rq);
 }
 
-extern void blk_dump_cmd(char *buf, struct request *rq);
-extern void blk_fill_rwbs(char *rwbs, unsigned int op, int bytes);
-
-#endif /* CONFIG_EVENT_TRACING && CONFIG_BLOCK */
+static inline unsigned int blk_rq_trace_nr_sectors(struct request *rq)
+{
+	return (rq->cmd_type != REQ_TYPE_FS) ? 0 : blk_rq_sectors(rq);
+}
 
 #endif

include/trace/events/block.h

@@ -73,19 +73,17 @@ DECLARE_EVENT_CLASS(block_rq_with_error,
 		__field(  unsigned int,	nr_sector		)
 		__field(  int,		errors			)
 		__array(  char,		rwbs,	RWBS_LEN	)
-		__dynamic_array( char,	cmd,	blk_cmd_buf_len(rq)	)
+		__dynamic_array( char,	cmd,	1		)
 	),
 
 	TP_fast_assign(
 		__entry->dev	   = rq->rq_disk ? disk_devt(rq->rq_disk) : 0;
-		__entry->sector    = (rq->cmd_type == REQ_TYPE_BLOCK_PC) ?
-					0 : blk_rq_pos(rq);
-		__entry->nr_sector = (rq->cmd_type == REQ_TYPE_BLOCK_PC) ?
-					0 : blk_rq_sectors(rq);
+		__entry->sector    = blk_rq_trace_sector(rq);
+		__entry->nr_sector = blk_rq_trace_nr_sectors(rq);
 		__entry->errors    = rq->errors;
 
 		blk_fill_rwbs(__entry->rwbs, rq->cmd_flags, blk_rq_bytes(rq));
-		blk_dump_cmd(__get_str(cmd), rq);
+		__get_str(cmd)[0] = '\0';
 	),
 
 	TP_printk("%d,%d %s (%s) %llu + %u [%d]",
@@ -153,7 +151,7 @@ TRACE_EVENT(block_rq_complete,
 		__field(  unsigned int,	nr_sector		)
 		__field(  int,		errors			)
 		__array(  char,		rwbs,	RWBS_LEN	)
-		__dynamic_array( char,	cmd,	blk_cmd_buf_len(rq)	)
+		__dynamic_array( char,	cmd,	1		)
 	),
 
 	TP_fast_assign(
@@ -163,7 +161,7 @@ TRACE_EVENT(block_rq_complete,
 		__entry->errors    = rq->errors;
 
 		blk_fill_rwbs(__entry->rwbs, rq->cmd_flags, nr_bytes);
-		blk_dump_cmd(__get_str(cmd), rq);
+		__get_str(cmd)[0] = '\0';
 	),
 
 	TP_printk("%d,%d %s (%s) %llu + %u [%d]",
@@ -186,20 +184,17 @@ DECLARE_EVENT_CLASS(block_rq,
 		__field(  unsigned int,	bytes			)
 		__array(  char,		rwbs,	RWBS_LEN	)
 		__array(  char,         comm,   TASK_COMM_LEN   )
-		__dynamic_array( char,	cmd,	blk_cmd_buf_len(rq)	)
+		__dynamic_array( char,	cmd,	1		)
 	),
 
 	TP_fast_assign(
 		__entry->dev	   = rq->rq_disk ? disk_devt(rq->rq_disk) : 0;
-		__entry->sector    = (rq->cmd_type == REQ_TYPE_BLOCK_PC) ?
-					0 : blk_rq_pos(rq);
-		__entry->nr_sector = (rq->cmd_type == REQ_TYPE_BLOCK_PC) ?
-					0 : blk_rq_sectors(rq);
-		__entry->bytes     = (rq->cmd_type == REQ_TYPE_BLOCK_PC) ?
-					blk_rq_bytes(rq) : 0;
+		__entry->sector    = blk_rq_trace_sector(rq);
+		__entry->nr_sector = blk_rq_trace_nr_sectors(rq);
+		__entry->bytes     = blk_rq_bytes(rq);
 
 		blk_fill_rwbs(__entry->rwbs, rq->cmd_flags, blk_rq_bytes(rq));
-		blk_dump_cmd(__get_str(cmd), rq);
+		__get_str(cmd)[0] = '\0';
 		memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
 	),
 

kernel/trace/blktrace.c

@@ -712,15 +712,13 @@ static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
 	if (likely(!bt))
 		return;
 
-	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
+	if (rq->cmd_type != REQ_TYPE_FS)
 		what |= BLK_TC_ACT(BLK_TC_PC);
-		__blk_add_trace(bt, 0, nr_bytes, req_op(rq), rq->cmd_flags,
-				what, rq->errors, rq->cmd_len, rq->cmd);
-	} else  {
+	else
 		what |= BLK_TC_ACT(BLK_TC_FS);
-		__blk_add_trace(bt, blk_rq_pos(rq), nr_bytes, req_op(rq),
-				rq->cmd_flags, what, rq->errors, 0, NULL);
-	}
+
+	__blk_add_trace(bt, blk_rq_trace_sector(rq), nr_bytes, req_op(rq),
+			rq->cmd_flags, what, rq->errors, 0, NULL);
 }
 
 static void blk_add_trace_rq_abort(void *ignore,
@@ -972,11 +970,7 @@ void blk_add_driver_data(struct request_queue *q,
 	if (likely(!bt))
 		return;
 
-	if (rq->cmd_type == REQ_TYPE_BLOCK_PC)
-		__blk_add_trace(bt, 0, blk_rq_bytes(rq), 0, 0,
-				BLK_TA_DRV_DATA, rq->errors, len, data);
-	else
-		__blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), 0, 0,
+	__blk_add_trace(bt, blk_rq_trace_sector(rq), blk_rq_bytes(rq), 0, 0,
 				BLK_TA_DRV_DATA, rq->errors, len, data);
 }
 EXPORT_SYMBOL_GPL(blk_add_driver_data);
@@ -1752,31 +1746,6 @@ void blk_trace_remove_sysfs(struct device *dev)
 
 #ifdef CONFIG_EVENT_TRACING
 
-void blk_dump_cmd(char *buf, struct request *rq)
-{
-	int i, end;
-	int len = rq->cmd_len;
-	unsigned char *cmd = rq->cmd;
-
-	if (rq->cmd_type != REQ_TYPE_BLOCK_PC) {
-		buf[0] = '\0';
-		return;
-	}
-
-	for (end = len - 1; end >= 0; end--)
-		if (cmd[end])
-			break;
-	end++;
-
-	for (i = 0; i < len; i++) {
-		buf += sprintf(buf, "%s%02x", i == 0 ? "" : " ", cmd[i]);
-		if (i == end && end != len - 1) {
-			sprintf(buf, " ..");
-			break;
-		}
-	}
-}
-
 void blk_fill_rwbs(char *rwbs, unsigned int op, int bytes)
 {
 	int i = 0;