diff options
| author | Yu Kuai <yukuai3@huawei.com> | 2023-11-25 16:16:04 +0800 |
|---|---|---|
| committer | Song Liu <song@kernel.org> | 2023-11-27 15:49:05 -0800 |
| commit | 7ecab28c3b2c26c1a51154d997433e8432eb49ba (patch) | |
| tree | 188da79cbd2529f2ca80abd84c5c5dfdc13d1fb2 /drivers/md | |
| parent | ad8606702f268903b26795e6b93605646fd1a6a8 (diff) | |
md/md-multipath: remove rcu protection to access rdev from conf
Because it's safe to accees rdev from conf:
- If any spinlock is held, because synchronize_rcu() from
md_kick_rdev_from_array() will prevent 'rdev' to be freed until
spinlock is released;
- If there is normal IO inflight, because mddev_suspend() will prevent
rdev to be added or removed from array;
And these will cover all the scenarios in md-multipath.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231125081604.3939938-6-yukuai1@huaweicloud.com
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/md-multipath.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/drivers/md/md-multipath.c b/drivers/md/md-multipath.c index aa77133f3188..19c8625ea642 100644 --- a/drivers/md/md-multipath.c +++ b/drivers/md/md-multipath.c @@ -32,17 +32,15 @@ static int multipath_map (struct mpconf *conf) * now we use the first available disk. */ - rcu_read_lock(); for (i = 0; i < disks; i++) { - struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev); + struct md_rdev *rdev = conf->multipaths[i].rdev; + if (rdev && test_bit(In_sync, &rdev->flags) && !test_bit(Faulty, &rdev->flags)) { atomic_inc(&rdev->nr_pending); - rcu_read_unlock(); return i; } } - rcu_read_unlock(); pr_crit_ratelimited("multipath_map(): no more operational IO paths?\n"); return (-1); @@ -137,14 +135,16 @@ static void multipath_status(struct seq_file *seq, struct mddev *mddev) struct mpconf *conf = mddev->private; int i; + lockdep_assert_held(&mddev->lock); + seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded); - rcu_read_lock(); for (i = 0; i < conf->raid_disks; i++) { - struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev); - seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_"); + struct md_rdev *rdev = READ_ONCE(conf->multipaths[i].rdev); + + seq_printf(seq, "%s", + rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_"); } - rcu_read_unlock(); seq_putc(seq, ']'); } @@ -182,7 +182,7 @@ static void multipath_error (struct mddev *mddev, struct md_rdev *rdev) conf->raid_disks - mddev->degraded); } -static void print_multipath_conf (struct mpconf *conf) +static void print_multipath_conf(struct mpconf *conf) { int i; struct multipath_info *tmp; @@ -195,6 +195,7 @@ static void print_multipath_conf (struct mpconf *conf) pr_debug(" --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded, conf->raid_disks); + lockdep_assert_held(&conf->mddev->reconfig_mutex); for (i = 0; i < conf->raid_disks; i++) { tmp = conf->multipaths + i; if (tmp->rdev) @@ -231,7 +232,7 @@ static int multipath_add_disk(struct mddev *mddev, struct md_rdev *rdev) rdev->raid_disk = path; set_bit(In_sync, &rdev->flags); spin_unlock_irq(&conf->device_lock); - rcu_assign_pointer(p->rdev, rdev); + WRITE_ONCE(p->rdev, rdev); err = 0; break; } @@ -257,7 +258,7 @@ static int multipath_remove_disk(struct mddev *mddev, struct md_rdev *rdev) err = -EBUSY; goto abort; } - p->rdev = NULL; + WRITE_ONCE(p->rdev, NULL); err = md_integrity_register(mddev); } abort: |