[v2] blktrace: Show requests without sector

Commit Message

Jan Kara Feb. 7, 2019, 10:55 a.m. UTC

Currently, blktrace will not show requests that don't have any data as
rq->__sector is initialized to -1 which is out of device range and thus
discarded by act_log_check(). This is most notably the case for cache
flush requests sent to the device. Fix the problem by making
blk_rq_trace_sector() return 0 for requests without initialized sector.

Reviewed-by: Johannes Thumshirn <[e-mail]>
Signed-off-by: Jan Kara <[e-mail]>
---
 include/linux/blktrace_api.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Jens Axboe Feb. 7, 2019, 7:57 p.m. UTC | #1

On 2/7/19 3:55 AM, Jan Kara wrote:
> Currently, blktrace will not show requests that don't have any data as
> rq->__sector is initialized to -1 which is out of device range and thus
> discarded by act_log_check(). This is most notably the case for cache
> flush requests sent to the device. Fix the problem by making
> blk_rq_trace_sector() return 0 for requests without initialized sector.

Much better, thanks. Applied.

Patch

diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index 8804753805ac..7bb2d8de9f30 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -116,7 +116,13 @@  extern void blk_fill_rwbs(char *rwbs, unsigned int op, int bytes);
 
 static inline sector_t blk_rq_trace_sector(struct request *rq)
 {
-	return blk_rq_is_passthrough(rq) ? 0 : blk_rq_pos(rq);
+	/*
+	 * Tracing should ignore starting sector for passthrough requests and
+	 * requests where starting sector didn't get set.
+	 */
+	if (blk_rq_is_passthrough(rq) || blk_rq_pos(rq) == (sector_t)-1)
+		return 0;
+	return blk_rq_pos(rq);
 }
 
 static inline unsigned int blk_rq_trace_nr_sectors(struct request *rq)