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Commit b0da3f0d authored by Jun'ichi Nomura's avatar Jun'ichi Nomura Committed by Jens Axboe
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Add a tracepoint for block request remapping 



Since 2.6.31 now has request-based device-mapper, it's useful to have
a tracepoint for request-remapping as well as bio-remapping.
This patch adds a tracepoint for request-remapping, trace_block_rq_remap().

Signed-off-by: default avatarKiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Alasdair G Kergon <agk@redhat.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 67efc925

block/blk-core.c

+1 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include "blk.h"



EXPORT_TRACEPOINT_SYMBOL_GPL(block_remap);

EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);

EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);



static int __make_request(struct request_queue *q, struct bio *bio);

include/linux/blktrace_api.h

+1 −1
Original line number Diff line number Diff line
@@ -212,7 +212,7 @@ extern struct attribute_group blk_trace_attr_group; 
# define blk_trace_startstop(q, start)			(-ENOTTY)

# define blk_trace_remove(q)				(-ENOTTY)

# define blk_add_trace_msg(q, fmt, ...)			do { } while (0)

# define blk_trace_remove_sysfs(struct device *dev)	do { } while (0)

# define blk_trace_remove_sysfs(dev)			do { } while (0)

static inline int blk_trace_init_sysfs(struct device *dev)

{

	return 0;

include/trace/events/block.h

+33 −0
Original line number Diff line number Diff line
@@ -488,6 +488,39 @@ TRACE_EVENT(block_remap, 
		  (unsigned long long)__entry->old_sector)

);



TRACE_EVENT(block_rq_remap,



	TP_PROTO(struct request_queue *q, struct request *rq, dev_t dev,

		 sector_t from),



	TP_ARGS(q, rq, dev, from),



	TP_STRUCT__entry(

		__field( dev_t,		dev		)

		__field( sector_t,	sector		)

		__field( unsigned int,	nr_sector	)

		__field( dev_t,		old_dev		)

		__field( sector_t,	old_sector	)

		__array( char,		rwbs,	6	)

	),



	TP_fast_assign(

		__entry->dev		= disk_devt(rq->rq_disk);

		__entry->sector		= blk_rq_pos(rq);

		__entry->nr_sector	= blk_rq_sectors(rq);

		__entry->old_dev	= dev;

		__entry->old_sector	= from;

		blk_fill_rwbs_rq(__entry->rwbs, rq);

	),



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

		  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)

);



#endif /* _TRACE_BLOCK_H */



/* This part must be outside protection */

kernel/trace/blktrace.c

+34 −0
Original line number Diff line number Diff line
@@ -855,6 +855,37 @@ static void blk_add_trace_remap(struct request_queue *q, struct bio *bio, 
			sizeof(r), &r);

}



/**

 * blk_add_trace_rq_remap - Add a trace for a request-remap operation

 * @q:		queue the io is for

 * @rq:		the source request

 * @dev:	target device

 * @from:	source sector

 *

 * Description:

 *     Device mapper remaps request to other devices.

 *     Add a trace for that action.

 *

 **/

static void blk_add_trace_rq_remap(struct request_queue *q,

				   struct request *rq, dev_t dev,

				   sector_t from)

{

	struct blk_trace *bt = q->blk_trace;

	struct blk_io_trace_remap r;



	if (likely(!bt))

		return;



	r.device_from = cpu_to_be32(dev);

	r.device_to   = cpu_to_be32(disk_devt(rq->rq_disk));

	r.sector_from = cpu_to_be64(from);



	__blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),

			rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,

			sizeof(r), &r);

}



/**

 * blk_add_driver_data - Add binary message with driver-specific data

 * @q:		queue the io is for
@@ -922,10 +953,13 @@ static void blk_register_tracepoints(void) 
	WARN_ON(ret);

	ret = register_trace_block_remap(blk_add_trace_remap);

	WARN_ON(ret);

	ret = register_trace_block_rq_remap(blk_add_trace_rq_remap);

	WARN_ON(ret);

}



static void blk_unregister_tracepoints(void)

{

	unregister_trace_block_rq_remap(blk_add_trace_rq_remap);

	unregister_trace_block_remap(blk_add_trace_remap);

	unregister_trace_block_split(blk_add_trace_split);

	unregister_trace_block_unplug_io(blk_add_trace_unplug_io);