diff options
author | Yu Kuai <yukuai3@huawei.com> | 2023-11-25 16:16:00 +0800 |
---|---|---|
committer | Song Liu <song@kernel.org> | 2023-11-27 15:49:04 -0800 |
commit | c891f1fd90e66e584bb1353e1859cef7c9eb36f8 (patch) | |
tree | 564d8541ff7bc4be1145f85bb0ef194c833ea587 /drivers/md/md.c | |
parent | bed9e27baf52a09b7ba2a3714f1e24e17ced386d (diff) |
md: remove flag RemoveSynchronized
rcu is not used correctly here, because synchronize_rcu() is called
before replacing old value, for example:
remove_and_add_spares // other path
synchronize_rcu
// called before replacing old value
set_bit(RemoveSynchronized)
rcu_read_lock()
rdev = conf->mirros[].rdev
pers->hot_remove_disk
conf->mirros[].rdev = NULL;
if (!test_bit(RemoveSynchronized))
synchronize_rcu
/*
* won't be called, and won't wait
* for concurrent readers to be done.
*/
// access rdev after remove_and_add_spares()
rcu_read_unlock()
Fortunately, there is a separate rcu protection to prevent such rdev
to be freed:
md_kick_rdev_from_array //other path
rcu_read_lock()
rdev = conf->mirros[].rdev
list_del_rcu(&rdev->same_set)
rcu_read_unlock()
/*
* rdev can be removed from conf, but
* rdev won't be freed.
*/
synchronize_rcu()
free rdev
Hence remove this useless flag and prepare to remove rcu protection to
access rdev from 'conf'.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231125081604.3939938-2-yukuai1@huaweicloud.com
Diffstat (limited to 'drivers/md/md.c')
-rw-r--r-- | drivers/md/md.c | 37 |
1 files changed, 6 insertions, 31 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index 466bbcb4e230..71b3397dea47 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -9244,44 +9244,19 @@ static int remove_and_add_spares(struct mddev *mddev, struct md_rdev *rdev; int spares = 0; int removed = 0; - bool remove_some = false; if (this && test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) /* Mustn't remove devices when resync thread is running */ return 0; rdev_for_each(rdev, mddev) { - if ((this == NULL || rdev == this) && - rdev->raid_disk >= 0 && - !test_bit(Blocked, &rdev->flags) && - test_bit(Faulty, &rdev->flags) && - atomic_read(&rdev->nr_pending)==0) { - /* Faulty non-Blocked devices with nr_pending == 0 - * never get nr_pending incremented, - * never get Faulty cleared, and never get Blocked set. - * So we can synchronize_rcu now rather than once per device - */ - remove_some = true; - set_bit(RemoveSynchronized, &rdev->flags); - } - } - - if (remove_some) - synchronize_rcu(); - rdev_for_each(rdev, mddev) { - if ((this == NULL || rdev == this) && - (test_bit(RemoveSynchronized, &rdev->flags) || - rdev_removeable(rdev))) { - if (mddev->pers->hot_remove_disk( - mddev, rdev) == 0) { - sysfs_unlink_rdev(mddev, rdev); - rdev->saved_raid_disk = rdev->raid_disk; - rdev->raid_disk = -1; - removed++; - } + if ((this == NULL || rdev == this) && rdev_removeable(rdev) && + !mddev->pers->hot_remove_disk(mddev, rdev)) { + sysfs_unlink_rdev(mddev, rdev); + rdev->saved_raid_disk = rdev->raid_disk; + rdev->raid_disk = -1; + removed++; } - if (remove_some && test_bit(RemoveSynchronized, &rdev->flags)) - clear_bit(RemoveSynchronized, &rdev->flags); } if (removed && mddev->kobj.sd) |