From d93f63028f3bc07bbcf6fe25d8d7d8a50f441bd9 Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Mon, 26 Mar 2012 15:49:13 +0200 Subject: [PATCH] drbd: Fix a potential write ordering issue on SyncTarget nodes Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg --- drivers/block/drbd/drbd_receiver.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c index caf3c3c..8a7f61b 100644 --- a/drivers/block/drbd/drbd_receiver.c +++ b/drivers/block/drbd/drbd_receiver.c @@ -1911,6 +1911,33 @@ static void update_peer_seq(struct drbd_conf *mdev, unsigned int peer_seq) } } +static inline int overlaps(sector_t s1, int l1, sector_t s2, int l2) +{ + return !((s1 + (l1>>9) <= s2) || (s1 >= s2 + (l2>>9))); +} + +/* maybe change sync_ee into interval trees as well? */ +static bool overlaping_resync_write(struct drbd_conf *mdev, struct drbd_peer_request *peer_req) +{ + struct drbd_peer_request *rs_req; + bool rv = 0; + + spin_lock_irq(&mdev->tconn->req_lock); + list_for_each_entry(rs_req, &mdev->sync_ee, w.list) { + if (overlaps(peer_req->i.sector, peer_req->i.size, + rs_req->i.sector, rs_req->i.size)) { + rv = 1; + break; + } + } + spin_unlock_irq(&mdev->tconn->req_lock); + + if (rv) + dev_warn(DEV, "WARN: Avoiding concurrent data/resync write to single sector.\n"); + + return rv; +} + /* Called from receive_Data. * Synchronize packets on sock with packets on msock. * @@ -2192,6 +2219,9 @@ static int receive_Data(struct drbd_tconn *tconn, struct packet_info *pi) list_add(&peer_req->w.list, &mdev->active_ee); spin_unlock_irq(&mdev->tconn->req_lock); + if (mdev->state.conn == C_SYNC_TARGET) + wait_event(mdev->ee_wait, !overlaping_resync_write(mdev, peer_req)); + if (mdev->tconn->agreed_pro_version < 100) { rcu_read_lock(); switch (rcu_dereference(mdev->tconn->net_conf)->wire_protocol) { -- 2.7.4