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Subject[PATCH 2/3] block: introduce BIO_IN_FLIGHT flag
Date
BIO_IN_FLIGHT flag is used for tracing block I/O completion.
This patch fixes tracing bio-based devices - except DM which
inserts completion tracepoint explicitly - that could not be
traced such event using blktrace.

It won't affect tracing normal (request-based) disk devices
and nested bio handling paths.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
---
block/blk-core.c | 5 +++++
fs/bio.c | 9 +++++++++
include/linux/blk_types.h | 1 +
3 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index a60b46cc9da5..d905f3c81ca7 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -164,6 +164,9 @@ static void req_bio_endio(struct request *rq, struct bio *bio,
if (unlikely(rq->cmd_flags & REQ_QUIET))
set_bit(BIO_QUIET, &bio->bi_flags);

+ /* completion event was already reported in blk_update_request */
+ clear_bit(BIO_IN_FLIGHT, &bio->bi_flags);
+
bio->bi_size -= nbytes;
bio->bi_sector += (nbytes >> 9);

@@ -1545,6 +1548,8 @@ static inline void __generic_make_request(struct bio *bio)

trace_block_bio_queue(q, bio);

+ set_bit(BIO_IN_FLIGHT, &bio->bi_flags);
+
ret = q->make_request_fn(q, bio);
} while (ret);

diff --git a/fs/bio.c b/fs/bio.c
index 9bfade8a609b..c510e93b6312 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -1447,6 +1447,15 @@ void bio_endio(struct bio *bio, int error)
else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
error = -EIO;

+ if (test_bit(BIO_IN_FLIGHT, &bio->bi_flags)) {
+ struct request_queue *q = bdev_get_queue(bio->bi_bdev);
+
+ trace_block_bio_complete(q, bio, error);
+
+ /* prevent duplicated completion event report */
+ clear_bit(BIO_IN_FLIGHT, &bio->bi_flags);
+ }
+
if (bio->bi_end_io)
bio->bi_end_io(bio, error);
}
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 32f0076e844b..daa81a7d1522 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -98,6 +98,7 @@ struct bio {
#define BIO_FS_INTEGRITY 10 /* fs owns integrity data, not block layer */
#define BIO_QUIET 11 /* Make BIO Quiet */
#define BIO_MAPPED_INTEGRITY 12/* integrity metadata has been remapped */
+#define BIO_IN_FLIGHT 13 /* report I/O completion event */
#define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag)))

/*
--
1.7.6


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