From: Dennis Zhou <dennis@kernel.org>
To: Jens Axboe <axboe@kernel.dk>, Tejun Heo <tj@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Josef Bacik <josef@toxicpanda.com>
Cc: kernel-team@fb.com, linux-block@vger.kernel.org,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
Dennis Zhou <dennis@kernel.org>, Alasdair Kergon <agk@redhat.com>,
Mike Snitzer <snitzer@redhat.com>
Subject: [PATCH 05/14] dm: set the static flush bio device on demand
Date: Tue, 4 Dec 2018 13:35:51 -0500 [thread overview]
Message-ID: <20181204183600.99746-6-dennis@kernel.org> (raw)
In-Reply-To: <20181204183600.99746-1-dennis@kernel.org>
The next patch changes the macro bio_set_dev() to associate a bio with a
blkg based on the device set. However, dm creates a static bio to be
used as the basis for cloning empty flush bios on creation. The
bio_set_dev() call in alloc_dev() will cause problems with the next
patch adding association to bio_set_dev() because the call is before the
bdev is associated with a gendisk (bd_disk is %NULL). To get around
this, set the device on the static bio every time and use that to clone
to the other bios.
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
---
block/bio.c | 1 +
drivers/md/dm.c | 12 +++++++++++-
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/block/bio.c b/block/bio.c
index 452b8e79b998..41ebb3f8e2fc 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -2021,6 +2021,7 @@ void bio_disassociate_blkg(struct bio *bio)
bio->bi_blkg = NULL;
}
}
+EXPORT_SYMBOL_GPL(bio_disassociate_blkg);
/**
* __bio_associate_blkg - associate a bio with the a blkg
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index a733e4c920af..a2d6f8b33d23 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1417,10 +1417,21 @@ static int __send_empty_flush(struct clone_info *ci)
unsigned target_nr = 0;
struct dm_target *ti;
+ /*
+ * Empty flush uses a statically initialized bio as the base for
+ * cloning, &md->flush_bio. However, blkg association requires that
+ * a bdev is associated with a gendisk, which doesn't happen until the
+ * bdev is opened. So, blkg association is done at issue time of the
+ * flush rather than when the device is created in dm_alloc().
+ */
+ bio_set_dev(ci->bio, ci->io->md->bdev);
+
BUG_ON(bio_has_data(ci->bio));
while ((ti = dm_table_get_target(ci->map, target_nr++)))
__send_duplicate_bios(ci, ti, ti->num_flush_bios, NULL);
+ bio_disassociate_blkg(ci->bio);
+
return 0;
}
@@ -1939,7 +1950,6 @@ static struct mapped_device *alloc_dev(int minor)
goto bad;
bio_init(&md->flush_bio, NULL, 0);
- bio_set_dev(&md->flush_bio, md->bdev);
md->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
dm_stats_init(&md->stats);
--
2.17.1
next prev parent reply other threads:[~2018-12-04 18:36 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-04 18:35 [PATCH v5 00/14] block: always associate blkg and refcount cleanup Dennis Zhou
2018-12-04 18:35 ` [PATCH 01/14] blkcg: fix ref count issue with bio_blkcg() using task_css Dennis Zhou
2018-12-04 18:35 ` [PATCH 02/14] blkcg: update blkg_lookup_create() to do locking Dennis Zhou
2018-12-04 18:35 ` [PATCH 03/14] blkcg: convert blkg_lookup_create() to find closest blkg Dennis Zhou
2018-12-04 18:35 ` [PATCH 04/14] blkcg: introduce common blkg association logic Dennis Zhou
2018-12-04 18:35 ` Dennis Zhou [this message]
2018-12-04 20:28 ` [PATCH 05/14] dm: set the static flush bio device on demand Mike Snitzer
2018-12-04 22:15 ` Dennis Zhou
2018-12-04 18:35 ` [PATCH 06/14] blkcg: associate blkg when associating a device Dennis Zhou
2018-12-04 19:48 ` Josef Bacik
2018-12-04 18:35 ` [PATCH 07/14] blkcg: consolidate bio_issue_init() to be a part of core Dennis Zhou
2018-12-04 19:50 ` Josef Bacik
2018-12-04 18:35 ` [PATCH 08/14] blkcg: associate a blkg for pages being evicted by swap Dennis Zhou
2018-12-04 18:35 ` [PATCH 09/14] blkcg: associate writeback bios with a blkg Dennis Zhou
2018-12-04 18:35 ` [PATCH 10/14] blkcg: remove bio->bi_css and instead use bio->bi_blkg Dennis Zhou
2018-12-04 18:35 ` [PATCH 11/14] blkcg: remove additional reference to the css Dennis Zhou
2018-12-04 19:53 ` Josef Bacik
2018-12-04 18:35 ` [PATCH 12/14] blkcg: remove bio_disassociate_task() Dennis Zhou
2018-12-04 19:53 ` Josef Bacik
2018-12-04 18:35 ` [PATCH 13/14] blkcg: change blkg reference counting to use percpu_ref Dennis Zhou
2018-12-04 19:54 ` Josef Bacik
2018-12-04 18:36 ` [PATCH 14/14] blkcg: rename blkg_try_get() to blkg_tryget() Dennis Zhou
2018-12-05 17:10 [PATCH v6 00/14] block: always associate blkg and refcount cleanup Dennis Zhou
2018-12-05 17:10 ` [PATCH 05/14] dm: set the static flush bio device on demand Dennis Zhou
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