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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 2012-06-08 14:17:36 +02:00 committed by Philipp Reisner
parent 1ed25b269e
commit 0d5934e3c2
1 changed files with 36 additions and 23 deletions
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59
drivers/block/drbd/drbd_req.c
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@ -770,6 +770,40 @@ static int drbd_may_do_local_read(struct drbd_conf *mdev, sector_t sector, int s
return 0 == drbd_bm_count_bits(mdev, sbnr, ebnr);
}
static void maybe_pull_ahead(struct drbd_conf *mdev)
{
int congested = 0;
/* 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.
* Note: caller has to make sure that net_conf is there.
*/
if (!get_ldev_if_state(mdev, D_UP_TO_DATE))
return;
if (mdev->net_conf->cong_fill &&
atomic_read(&mdev->ap_in_flight) >= mdev->net_conf->cong_fill) {
dev_info(DEV, "Congestion-fill threshold reached\n");
congested = 1;
}
if (mdev->act_log->used >= mdev->net_conf->cong_extents) {
dev_info(DEV, "Congestion-extents threshold reached\n");
congested = 1;
}
if (congested) {
queue_barrier(mdev); /* last barrier, after mirrored writes */
if (mdev->net_conf->on_congestion == OC_PULL_AHEAD)
_drbd_set_state(_NS(mdev, conn, C_AHEAD), 0, NULL);
else /*mdev->net_conf->on_congestion == OC_DISCONNECT */
_drbd_set_state(_NS(mdev, conn, C_DISCONNECTING), 0, NULL);
}
put_ldev(mdev);
}
static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio, unsigned long start_time)
{
const int rw = bio_rw(bio);
@ -977,29 +1011,8 @@ allocate_barrier:
_req_mod(req, queue_for_send_oos);
if (remote &&
mdev->net_conf->on_congestion != OC_BLOCK && mdev->agreed_pro_version >= 96) {
int congested = 0;
if (mdev->net_conf->cong_fill &&
atomic_read(&mdev->ap_in_flight) >= mdev->net_conf->cong_fill) {
dev_info(DEV, "Congestion-fill threshold reached\n");
congested = 1;
}
if (mdev->act_log->used >= mdev->net_conf->cong_extents) {
dev_info(DEV, "Congestion-extents threshold reached\n");
congested = 1;
}
if (congested) {
queue_barrier(mdev); /* last barrier, after mirrored writes */
if (mdev->net_conf->on_congestion == OC_PULL_AHEAD)
_drbd_set_state(_NS(mdev, conn, C_AHEAD), 0, NULL);
else /*mdev->net_conf->on_congestion == OC_DISCONNECT */
_drbd_set_state(_NS(mdev, conn, C_DISCONNECTING), 0, NULL);
}
}
mdev->net_conf->on_congestion != OC_BLOCK && mdev->agreed_pro_version >= 96)
maybe_pull_ahead(mdev);
spin_unlock_irq(&mdev->req_lock);
kfree(b); /* if someone else has beaten us to it... */