md/raid10: check In_sync flag in 'enough()'.
It isn't really enough to check that the rdev is present, we need to
also be sure that the device is still In_sync.
Doing this requires using rcu_dereference to access the rdev, and
holding the rcu_read_lock() to ensure the rdev doesn't disappear while
we look at it.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 5169ed2..aa8ba07 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1633,6 +1633,7 @@
static int _enough(struct r10conf *conf, int previous, int ignore)
{
int first = 0;
+ int has_enough = 0;
int disks, ncopies;
if (previous) {
disks = conf->prev.raid_disks;
@@ -1642,21 +1643,27 @@
ncopies = conf->geo.near_copies;
}
+ rcu_read_lock();
do {
int n = conf->copies;
int cnt = 0;
int this = first;
while (n--) {
- if (conf->mirrors[this].rdev &&
- this != ignore)
+ struct md_rdev *rdev;
+ if (this != ignore &&
+ (rdev = rcu_dereference(conf->mirrors[this].rdev)) &&
+ test_bit(In_sync, &rdev->flags))
cnt++;
this = (this+1) % disks;
}
if (cnt == 0)
- return 0;
+ goto out;
first = (first + ncopies) % disks;
} while (first != 0);
- return 1;
+ has_enough = 1;
+out:
+ rcu_read_unlock();
+ return has_enough;
}
static int enough(struct r10conf *conf, int ignore)