blktrace: correct remap names

This attempts to clarify names utilized during block I/O remap
operations (partition, volume manager). It correctly matches up the
/from/ information for both device & sector. This takes in the concept
from Kosaki Motohiro and extends it to include better naming for the
"device_from" field.

[ Impact: cleanup ]

Signed-off-by: Alan D. Brunelle <[email protected]>
Reviewed-by: Li Zefan <[email protected]>
Reviewed-by: KOSAKI Motohiro <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

include/linux/blktrace_api.h

@@ -116,9 +116,9 @@ struct blk_io_trace {
  * The remap event
  */
 struct blk_io_trace_remap {
-	__be32 device;
 	__be32 device_from;
-	__be64 sector;
+	__be32 device_to;
+	__be64 sector_from;
 };
 
 enum {

include/trace/block.h

@@ -70,7 +70,7 @@ DECLARE_TRACE(block_split,
 
 DECLARE_TRACE(block_remap,
 	TP_PROTO(struct request_queue *q, struct bio *bio, dev_t dev,
-		 sector_t from, sector_t to),
-	      TP_ARGS(q, bio, dev, from, to));
+		 sector_t to, sector_t from),
+	      TP_ARGS(q, bio, dev, to, from));
 
 #endif

kernel/trace/blktrace.c

@@ -830,26 +830,26 @@ static void blk_add_trace_split(struct request_queue *q, struct bio *bio,
  * @q:		queue the io is for
  * @bio:	the source bio
  * @dev:	target device
- * @from:	source sector
  * @to:		target sector
+ * @from:	source sector
  *
  * Description:
  *     Device mapper or raid target sometimes need to split a bio because
  *     it spans a stripe (or similar). Add a trace for that action.
  *
  **/
 static void blk_add_trace_remap(struct request_queue *q, struct bio *bio,
-				       dev_t dev, sector_t from, sector_t to)
+				       dev_t dev, sector_t to, sector_t from)
 {
 	struct blk_trace *bt = q->blk_trace;
 	struct blk_io_trace_remap r;
 
 	if (likely(!bt))
 		return;
 
-	r.device = cpu_to_be32(dev);
-	r.device_from = cpu_to_be32(bio->bi_bdev->bd_dev);
-	r.sector = cpu_to_be64(to);
+	r.device_from = cpu_to_be32(dev);
+	r.device_to   = cpu_to_be32(bio->bi_bdev->bd_dev);
+	r.sector_from = cpu_to_be64(from);
 
 	__blk_add_trace(bt, from, bio->bi_size, bio->bi_rw, BLK_TA_REMAP,
 			!bio_flagged(bio, BIO_UPTODATE), sizeof(r), &r);
@@ -1028,11 +1028,11 @@ static void get_pdu_remap(const struct trace_entry *ent,
 			  struct blk_io_trace_remap *r)
 {
 	const struct blk_io_trace_remap *__r = pdu_start(ent);
-	__u64 sector = __r->sector;
+	__u64 sector_from = __r->sector_from;
 
-	r->device = be32_to_cpu(__r->device);
 	r->device_from = be32_to_cpu(__r->device_from);
-	r->sector = be64_to_cpu(sector);
+	r->device_to   = be32_to_cpu(__r->device_to);
+	r->sector_from = be64_to_cpu(sector_from);
 }
 
 typedef int (blk_log_action_t) (struct trace_iterator *iter, const char *act);
@@ -1148,13 +1148,13 @@ static int blk_log_with_error(struct trace_seq *s,
 
 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)
 {
-	struct blk_io_trace_remap r = { .device = 0, };
+	struct blk_io_trace_remap r = { .device_from = 0, };
 
 	get_pdu_remap(ent, &r);
 	return trace_seq_printf(s, "%llu + %u <- (%d,%d) %llu\n",
-			       t_sector(ent),
-			       t_sec(ent), MAJOR(r.device), MINOR(r.device),
-			       (unsigned long long)r.sector);
+				t_sector(ent), t_sec(ent),
+				MAJOR(r.device_from), MINOR(r.device_from),
+				(unsigned long long)r.sector_from);
 }
 
 static int blk_log_plug(struct trace_seq *s, const struct trace_entry *ent)