6.4-stable review patch. If anyone has any objections, please let me know.
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From: Li Nan linan122@huawei.com
[ 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 --- drivers/md/raid10.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-)
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index ee75b058438f3..f47fd50651c45 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -1321,6 +1321,25 @@ 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; @@ -1464,15 +1483,7 @@ 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)))