drbd: add lists to find oldest pending requests

Adding requests to per-device fifo lists as soon as possible after
allocating them leaves a simple list_first_entry_or_null() to find the
oldest request, regardless what it is still waiting for.

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

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 08fa2dc8cdba..f29f107be9b8 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -318,6 +318,10 @@ struct drbd_request {
         struct list_head tl_requests; /* ring list in the transfer log */
         struct bio *master_bio;       /* master bio pointer */
 
+        /* see struct drbd_device */
+        struct list_head req_pending_master_completion;
+        struct list_head req_pending_local;
+
         /* for generic IO accounting */
         unsigned long start_jif;
 
@@ -738,7 +742,7 @@ struct submit_worker {
         struct workqueue_struct *wq;
         struct work_struct worker;
 
-        spinlock_t lock;
+        /* protected by ..->resource->req_lock */
         struct list_head writes;
 };
 
@@ -795,6 +799,11 @@ struct drbd_device {
         struct rb_root read_requests;
         struct rb_root write_requests;
 
+        /* for statistics and timeouts */
+        /* [0] read, [1] write */
+        struct list_head pending_master_completion[2];
+        struct list_head pending_completion[2];
+
         /* use checksums for *this* resync */
         bool use_csums;
         /* blocks to resync in this run [unit BM_BLOCK_SIZE] */