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authorLars Ellenberg <lars.ellenberg@linbit.com>2012-06-08 14:17:36 +0200
committerPhilipp Reisner <philipp.reisner@linbit.com>2012-06-12 14:35:19 +0200
commit0d5934e3c258fc5decc4103600c597086fd95a52 (patch)
tree1e9810b23c495ffed5f9d1814ea74535b6013ea5 /drivers/block/drbd
parent1ed25b269e3dd5ecc64f17beef9ea21745c39ca6 (diff)
downloadvexpress-lsk-0d5934e3c258fc5decc4103600c597086fd95a52.tar.gz
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>
Diffstat (limited to 'drivers/block/drbd')
-rw-r--r--drivers/block/drbd/drbd_req.c59
1 files 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... */