[PATCH -next 2/8] md: also clone new io if io accounting is disabled

[Yu Kuai]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

Currently, 'active_io' is grabed before make_reqeust() is called, and
it's dropped immediately make_reqeust() returns. Hence 'active_io'
actually means io is dispatching, not io is inflight.

For raid0 and raid456 that io accounting is enabled, 'active_io' will
also be grabed when bio is cloned for io accounting, and this 'active_io'
is dropped until io is done.

Always clone new bio so that 'active_io' will mean that io is inflight,
raid1 and raid10 will switch to use this method in later patches. Once
these are implemented, it can be cleaned up that 'active_io' is grabed
twice for one io.

Now that bio will be cloned even if io accounting is disabled, also
rename related structure from '*_acct_*' to '*_clone_*'.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
 drivers/md/md.c    | 61 ++++++++++++++++++++++++----------------------
 drivers/md/md.h    |  4 +--
 drivers/md/raid5.c | 18 +++++++-------
 3 files changed, 43 insertions(+), 40 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 42347289195a..5ad8e7f3aebd 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2314,7 +2314,7 @@ int md_integrity_register(struct mddev *mddev)
 	pr_debug("md: data integrity enabled on %s\n", mdname(mddev));
 	if (bioset_integrity_create(&mddev->bio_set, BIO_POOL_SIZE) ||
 	    (mddev->level != 1 && mddev->level != 10 &&
-	     bioset_integrity_create(&mddev->io_acct_set, BIO_POOL_SIZE))) {
+	     bioset_integrity_create(&mddev->io_clone_set, BIO_POOL_SIZE))) {
 		/*
 		 * No need to handle the failure of bioset_integrity_create,
 		 * because the function is called by md_run() -> pers->run(),
@@ -5886,9 +5886,9 @@ int md_run(struct mddev *mddev)
 			goto exit_bio_set;
 	}
 
-	if (!bioset_initialized(&mddev->io_acct_set)) {
-		err = bioset_init(&mddev->io_acct_set, BIO_POOL_SIZE,
-				  offsetof(struct md_io_acct, bio_clone), 0);
+	if (!bioset_initialized(&mddev->io_clone_set)) {
+		err = bioset_init(&mddev->io_clone_set, BIO_POOL_SIZE,
+				  offsetof(struct md_io_clone, bio_clone), 0);
 		if (err)
 			goto exit_sync_set;
 	}
@@ -6070,7 +6070,7 @@ int md_run(struct mddev *mddev)
 	module_put(pers->owner);
 	md_bitmap_destroy(mddev);
 abort:
-	bioset_exit(&mddev->io_acct_set);
+	bioset_exit(&mddev->io_clone_set);
 exit_sync_set:
 	bioset_exit(&mddev->sync_set);
 exit_bio_set:
@@ -6295,7 +6295,7 @@ static void __md_stop(struct mddev *mddev)
 	percpu_ref_exit(&mddev->active_io);
 	bioset_exit(&mddev->bio_set);
 	bioset_exit(&mddev->sync_set);
-	bioset_exit(&mddev->io_acct_set);
+	bioset_exit(&mddev->io_clone_set);
 }
 
 void md_stop(struct mddev *mddev)
@@ -8661,45 +8661,48 @@ void md_submit_discard_bio(struct mddev *mddev, struct md_rdev *rdev,
 }
 EXPORT_SYMBOL_GPL(md_submit_discard_bio);
 
-static void md_end_io_acct(struct bio *bio)
+static void md_end_clone_io(struct bio *bio)
 {
-	struct md_io_acct *md_io_acct = bio->bi_private;
-	struct bio *orig_bio = md_io_acct->orig_bio;
-	struct mddev *mddev = md_io_acct->mddev;
+	struct md_io_clone *md_io_clone = bio->bi_private;
+	struct bio *orig_bio = md_io_clone->orig_bio;
+	struct mddev *mddev = md_io_clone->mddev;
 
 	orig_bio->bi_status = bio->bi_status;
 
-	bio_end_io_acct(orig_bio, md_io_acct->start_time);
+	if (md_io_clone->start_time)
+		bio_end_io_acct(orig_bio, md_io_clone->start_time);
+
 	bio_put(bio);
 	bio_endio(orig_bio);
-
 	percpu_ref_put(&mddev->active_io);
 }
 
+static void md_clone_bio(struct mddev *mddev, struct bio **bio)
+{
+	struct block_device *bdev = (*bio)->bi_bdev;
+	struct md_io_clone *md_io_clone;
+	struct bio *clone =
+		bio_alloc_clone(bdev, *bio, GFP_NOIO, &mddev->io_clone_set);
+
+	md_io_clone = container_of(clone, struct md_io_clone, bio_clone);
+	md_io_clone->orig_bio = *bio;
+	md_io_clone->mddev = mddev;
+	if (blk_queue_io_stat(bdev->bd_disk->queue))
+		md_io_clone->start_time = bio_start_io_acct(*bio);
+
+	clone->bi_end_io = md_end_clone_io;
+	clone->bi_private = md_io_clone;
+	*bio = clone;
+}
+
 /*
  * Used by personalities that don't already clone the bio and thus can't
  * easily add the timestamp to their extended bio structure.
  */
 void md_account_bio(struct mddev *mddev, struct bio **bio)
 {
-	struct block_device *bdev = (*bio)->bi_bdev;
-	struct md_io_acct *md_io_acct;
-	struct bio *clone;
-
-	if (!blk_queue_io_stat(bdev->bd_disk->queue))
-		return;
-
 	percpu_ref_get(&mddev->active_io);
-
-	clone = bio_alloc_clone(bdev, *bio, GFP_NOIO, &mddev->io_acct_set);
-	md_io_acct = container_of(clone, struct md_io_acct, bio_clone);
-	md_io_acct->orig_bio = *bio;
-	md_io_acct->start_time = bio_start_io_acct(*bio);
-	md_io_acct->mddev = mddev;
-
-	clone->bi_end_io = md_end_io_acct;
-	clone->bi_private = md_io_acct;
-	*bio = clone;
+	md_clone_bio(mddev, bio);
 }
 EXPORT_SYMBOL_GPL(md_account_bio);
 
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 11299d94b239..892a598a5029 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -510,7 +510,7 @@ struct mddev {
 	struct bio_set			sync_set; /* for sync operations like
 						   * metadata and bitmap writes
 						   */
-	struct bio_set			io_acct_set; /* for raid0 and raid5 io accounting */
+	struct bio_set			io_clone_set;
 
 	/* Generic flush handling.
 	 * The last to finish preflush schedules a worker to submit
@@ -738,7 +738,7 @@ struct md_thread {
 	void			*private;
 };
 
-struct md_io_acct {
+struct md_io_clone {
 	struct mddev	*mddev;
 	struct bio	*orig_bio;
 	unsigned long	start_time;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 29cf5455d7a5..cef0b400b2ee 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5468,13 +5468,13 @@ static struct bio *remove_bio_from_retry(struct r5conf *conf,
  */
 static void raid5_align_endio(struct bio *bi)
 {
-	struct md_io_acct *md_io_acct = bi->bi_private;
-	struct bio *raid_bi = md_io_acct->orig_bio;
+	struct md_io_clone *md_io_clone = bi->bi_private;
+	struct bio *raid_bi = md_io_clone->orig_bio;
 	struct mddev *mddev;
 	struct r5conf *conf;
 	struct md_rdev *rdev;
 	blk_status_t error = bi->bi_status;
-	unsigned long start_time = md_io_acct->start_time;
+	unsigned long start_time = md_io_clone->start_time;
 
 	bio_put(bi);
 
@@ -5506,7 +5506,7 @@ static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
 	struct md_rdev *rdev;
 	sector_t sector, end_sector, first_bad;
 	int bad_sectors, dd_idx;
-	struct md_io_acct *md_io_acct;
+	struct md_io_clone *md_io_clone;
 	bool did_inc;
 
 	if (!in_chunk_boundary(mddev, raid_bio)) {
@@ -5544,15 +5544,15 @@ static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
 	}
 
 	align_bio = bio_alloc_clone(rdev->bdev, raid_bio, GFP_NOIO,
-				    &mddev->io_acct_set);
-	md_io_acct = container_of(align_bio, struct md_io_acct, bio_clone);
+				    &mddev->io_clone_set);
+	md_io_clone = container_of(align_bio, struct md_io_clone, bio_clone);
 	raid_bio->bi_next = (void *)rdev;
 	if (blk_queue_io_stat(raid_bio->bi_bdev->bd_disk->queue))
-		md_io_acct->start_time = bio_start_io_acct(raid_bio);
-	md_io_acct->orig_bio = raid_bio;
+		md_io_clone->start_time = bio_start_io_acct(raid_bio);
+	md_io_clone->orig_bio = raid_bio;
 
 	align_bio->bi_end_io = raid5_align_endio;
-	align_bio->bi_private = md_io_acct;
+	align_bio->bi_private = md_io_clone;
 	align_bio->bi_iter.bi_sector = sector;
 
 	/* No reshape active, so we can trust rdev->data_offset */
-- 
2.39.2