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Commit 75afb352 authored by Jun'ichi Nomura's avatar Jun'ichi Nomura Committed by Jens Axboe
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block: Add nr_bios to block_rq_remap tracepoint 

Adding the number of bios in a remapped request to 'block_rq_remap'
tracepoint.

Request remapper clones bios in a request to track the completion
status of each bio. So the number of bios can be useful information
for investigation.

Related discussions:
  http://www.redhat.com/archives/dm-devel/2013-August/msg00084.html
  http://www.redhat.com/archives/dm-devel/2013-September/msg00024.html



Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: default avatarMike Snitzer <snitzer@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7652113c

include/linux/blkdev.h

+11 −0
Original line number Diff line number Diff line
@@ -862,6 +862,17 @@ static inline unsigned int blk_rq_get_max_sectors(struct request *rq) 
	return blk_queue_get_max_sectors(q, rq->cmd_flags);

}



static inline unsigned int blk_rq_count_bios(struct request *rq)

{

	unsigned int nr_bios = 0;

	struct bio *bio;



	__rq_for_each_bio(bio, rq)

		nr_bios++;



	return nr_bios;

}



/*

 * Request issue related functions.

 */

include/trace/events/block.h

+4 −2
Original line number Diff line number Diff line
@@ -618,6 +618,7 @@ TRACE_EVENT(block_rq_remap, 
		__field( unsigned int,	nr_sector	)

		__field( dev_t,		old_dev		)

		__field( sector_t,	old_sector	)

		__field( unsigned int,	nr_bios		)

		__array( char,		rwbs,	RWBS_LEN)

	),
@@ -627,15 +628,16 @@ TRACE_EVENT(block_rq_remap, 
		__entry->nr_sector	= blk_rq_sectors(rq);

		__entry->old_dev	= dev;

		__entry->old_sector	= from;

		__entry->nr_bios	= blk_rq_count_bios(rq);

		blk_fill_rwbs(__entry->rwbs, rq->cmd_flags, blk_rq_bytes(rq));

	),



	TP_printk("%d,%d %s %llu + %u <- (%d,%d) %llu",

	TP_printk("%d,%d %s %llu + %u <- (%d,%d) %llu %u",

		  MAJOR(__entry->dev), MINOR(__entry->dev), __entry->rwbs,

		  (unsigned long long)__entry->sector,

		  __entry->nr_sector,

		  MAJOR(__entry->old_dev), MINOR(__entry->old_dev),

		  (unsigned long long)__entry->old_sector)

		  (unsigned long long)__entry->old_sector, __entry->nr_bios)

);



#endif /* _TRACE_BLOCK_H */