drbd: Add read_requests tree

We do not do collision detection for read requests, but we still need to
look up the request objects when we receive a package over the network.
Using the same data structure for read and write requests results in
simpler code once the tl_hash and app_reads_hash tables are removed.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 593576fcf64e..d2a78c4ee919 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -260,10 +260,15 @@ void _req_may_be_done(struct drbd_request *req, struct bio_and_error *m)
 
                 /* remove the request from the conflict detection
                  * respective block_id verification hash */
-                if (!hlist_unhashed(&req->collision)) {
+                if (!drbd_interval_empty(&req->i)) {
+                        struct rb_root *root;
+
                         hlist_del(&req->collision);
-                        if (!drbd_interval_empty(&req->i))
-                                drbd_remove_interval(&mdev->write_requests, &req->i);
+                        if (rw == WRITE)
+                                root = &mdev->write_requests;
+                        else
+                                root = &mdev->read_requests;
+                        drbd_remove_interval(root, &req->i);
                 } else
                         D_ASSERT((s & (RQ_NET_MASK & ~RQ_NET_DONE)) == 0);
 
@@ -332,6 +337,7 @@ static int _req_conflicts(struct drbd_request *req)
         struct hlist_head *slot;
 
         D_ASSERT(hlist_unhashed(&req->collision));
+        D_ASSERT(drbd_interval_empty(&req->i));
 
         if (!get_net_conf(mdev))
                 return 0;
@@ -493,6 +499,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
                 /* so we can verify the handle in the answer packet
                  * corresponding hlist_del is in _req_may_be_done() */
                 hlist_add_head(&req->collision, ar_hash_slot(mdev, req->i.sector));
+                drbd_insert_interval(&mdev->read_requests, &req->i);
 
                 set_bit(UNPLUG_REMOTE, &mdev->flags);