From 0d5934e3c258fc5decc4103600c597086fd95a52 Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Fri, 8 Jun 2012 14:17:36 +0200 Subject: [PATCH] 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 Signed-off-by: Lars Ellenberg --- drivers/block/drbd/drbd_req.c | 59 +++++++++++++++++++++-------------- 1 file changed, 36 insertions(+), 23 deletions(-) diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c index 773f4e2d3c1..8e93a6ac9bb 100644 --- a/drivers/block/drbd/drbd_req.c +++ b/drivers/block/drbd/drbd_req.c @@ -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... */