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>

3 files changed, 13 insertions, 4 deletions

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 058371318da4..46a4332d3441 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1019,7 +1019,8 @@ struct drbd_conf {
         struct hlist_head *tl_hash;
         unsigned int tl_hash_s;
 
-        /* Interval tree of pending local write requests */
+        /* Interval tree of pending local requests */
+        struct rb_root read_requests;
         struct rb_root write_requests;
 
         /* blocks to resync in this run [unit BM_BLOCK_SIZE] */
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 4d85838f53e3..c0ea5baa9a1b 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -3473,6 +3473,7 @@ struct drbd_conf *drbd_new_device(unsigned int minor)
         /* no need to lock access, we are still initializing this minor device. */
         if (!tl_init(mdev))
                 goto out_no_tl;
+        mdev->read_requests = RB_ROOT;
         mdev->write_requests = RB_ROOT;
 
         mdev->app_reads_hash = kzalloc(APP_R_HSIZE*sizeof(void *), GFP_KERNEL);
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);