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drbd: fix null pointer dereference with on-congestion policy when diskless 

We must not look at mdev->actlog, unless we have a get_ldev() reference.
It also does not make much sense to try to disconnect or pull-ahead of
the peer, if we don't have good local data.

Only even consider congestion policies, if our local disk is D_UP_TO_DATE.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Lars Ellenberg 2012-07-30 09:06:26 +02:00 committed by Philipp Reisner
parent 27012382bc
commit 3b9ef85e05
1 changed files with 11 additions and 5 deletions
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16
drivers/block/drbd/drbd_req.c
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@ -823,7 +823,7 @@ static void complete_conflicting_writes(struct drbd_request *req)
}
/* called within req_lock and rcu_read_lock() */
static bool conn_check_congested(struct drbd_conf *mdev)
static void maybe_pull_ahead(struct drbd_conf *mdev)
{
struct drbd_tconn *tconn = mdev->tconn;
struct net_conf *nc;
@ -834,7 +834,14 @@ static bool conn_check_congested(struct drbd_conf *mdev)
on_congestion = nc ? nc->on_congestion : OC_BLOCK;
if (on_congestion == OC_BLOCK ||
tconn->agreed_pro_version < 96)
return false;
return;
/* If I don't even have good local storage, we can not reasonably try
* to pull ahead of the peer. We also need the local reference to make
* sure mdev->act_log is there.
*/
if (!get_ldev_if_state(mdev, D_UP_TO_DATE))
return;
if (nc->cong_fill &&
atomic_read(&mdev->ap_in_flight) >= nc->cong_fill) {
@ -857,8 +864,7 @@ static bool conn_check_congested(struct drbd_conf *mdev)
else /*nc->on_congestion == OC_DISCONNECT */
_drbd_set_state(_NS(mdev, conn, C_DISCONNECTING), 0, NULL);
}
return congested;
put_ldev(mdev);
}
/* If this returns false, and req->private_bio is still set,
@ -923,7 +929,7 @@ static int drbd_process_write_request(struct drbd_request *req)
rcu_read_lock();
remote = drbd_should_do_remote(mdev->state);
if (remote) {
conn_check_congested(mdev);
maybe_pull_ahead(mdev);
remote = drbd_should_do_remote(mdev->state);
}
send_oos = drbd_should_send_out_of_sync(mdev->state);