summaryrefslogtreecommitdiff
path: root/drivers/md
diff options
context:
space:
mode:
authorYu Kuai <yukuai3@huawei.com>2023-11-25 16:16:04 +0800
committerSong Liu <song@kernel.org>2023-11-27 15:49:05 -0800
commit7ecab28c3b2c26c1a51154d997433e8432eb49ba (patch)
tree188da79cbd2529f2ca80abd84c5c5dfdc13d1fb2 /drivers/md
parentad8606702f268903b26795e6b93605646fd1a6a8 (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.c23
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: