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md/raid10: factor out dereference_rdev_and_rrdev()

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[ Upstream commit b99f8fd2d91eb734f13098aa1cf337edaca454b7 ]

Factor out a helper to get 'rdev' and 'replacement' from config->mirrors.
Just to make code cleaner and prepare to fix the bug of io loss while
'replacement' replace 'rdev'.

There is no functional change.

Signed-off-by: Li Nan <linan122@huawei.com>
Link: https://lore.kernel.org/r/20230701080529.2684932-3-linan666@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>
Stable-dep-of: 673643490b9a ("md/raid10: use dereference_rdev_and_rrdev() to get devices")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Li Nan 2023-07-01 16:05:28 +08:00 committed by Greg Kroah-Hartman
parent 097f30f0ce
commit 27acd8c131
1 changed files with 20 additions and 9 deletions
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29
drivers/md/raid10.c
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@ -1317,6 +1317,25 @@ static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
}
}
static struct md_rdev *dereference_rdev_and_rrdev(struct raid10_info *mirror,
struct md_rdev **prrdev)
{
struct md_rdev *rdev, *rrdev;
rrdev = rcu_dereference(mirror->replacement);
/*
* Read replacement first to prevent reading both rdev and
* replacement as NULL during replacement replace rdev.
*/
smp_mb();
rdev = rcu_dereference(mirror->rdev);
if (rdev == rrdev)
rrdev = NULL;
*prrdev = rrdev;
return rdev;
}
static void wait_blocked_dev(struct mddev *mddev, struct r10bio *r10_bio)
{
int i;
@ -1460,15 +1479,7 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
int d = r10_bio->devs[i].devnum;
struct md_rdev *rdev, *rrdev;
rrdev = rcu_dereference(conf->mirrors[d].replacement);
/*
* Read replacement first to prevent reading both rdev and
* replacement as NULL during replacement replace rdev.
*/
smp_mb();
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev == rrdev)
rrdev = NULL;
rdev = dereference_rdev_and_rrdev(&conf->mirrors[d], &rrdev);
if (rdev && (test_bit(Faulty, &rdev->flags)))
rdev = NULL;
if (rrdev && (test_bit(Faulty, &rrdev->flags)))