[md PATCH 14/18] md/raid5: add rcu protection to rdev accesses in want_replace

NeilBrown
2016-06-02T06:19:52Z

Being in the middle of resync is no longer protection against failed
rdevs disappearing. So add rcu protection.

Signed-off-by: NeilBrown <neilb@suse.com>
---
drivers/md/raid5.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index e9ad22d64bd7..7da89ee22a31 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3239,15 +3239,16 @@ static int want_replace(struct stripe_head *sh, int disk_idx)
{
struct md_rdev *rdev;
int rv = 0;
- /* Doing recovery so rcu locking not required */
- rdev = sh->raid_conf->disks[disk_idx].replacement;
+
+ rcu_read_lock();
+ rdev = rcu_dereference(sh->raid_conf->disks[disk_idx].replacement);
if (rdev
&& !test_bit(Faulty, &rdev->flags)
&& !test_bit(In_sync, &rdev->flags)
&& (rdev->recovery_offset <= sh->sector
|| rdev->mddev->recovery_cp <= sh->sector))
rv = 1;
-
+ rcu_read_unlock();
return rv;
}