drbd: Replaced some casts by an union. Improved comments

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

3 files changed, 12 insertions, 8 deletions

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index facb72ccc56b..b0cbfa143775 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -759,7 +759,7 @@ struct digest_info {
 struct drbd_epoch_entry {
         struct drbd_work w;
         struct hlist_node colision;
-        struct drbd_epoch *epoch;
+        struct drbd_epoch *epoch; /* for writes */
         struct drbd_conf *mdev;
         struct page *pages;
         atomic_t pending_bios;
@@ -767,7 +767,10 @@ struct drbd_epoch_entry {
         /* see comments on ee flag bits below */
         unsigned long flags;
         sector_t sector;
-        u64 block_id;
+        union {
+                u64 block_id;
+                struct digest_info *digest;
+        };
 };
 
 /* ee flag bits.
@@ -1032,10 +1035,10 @@ struct drbd_conf {
         spinlock_t epoch_lock;
         unsigned int epochs;
         enum write_ordering_e write_ordering;
-        struct list_head active_ee; /* IO in progress */
-        struct list_head sync_ee;   /* IO in progress */
+        struct list_head active_ee; /* IO in progress (P_DATA gets written to disk) */
+        struct list_head sync_ee;   /* IO in progress (P_RS_DATA_REPLY gets written to disk) */
         struct list_head done_ee;   /* send ack */
-        struct list_head read_ee;   /* IO in progress */
+        struct list_head read_ee;   /* IO in progress (any read) */
         struct list_head net_ee;    /* zero-copy network send in progress */
         struct hlist_head *ee_hash; /* is proteced by req_lock! */
         unsigned int ee_hash_s;
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 5f80b22e711d..0b03e3174f76 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -2097,7 +2097,7 @@ static int receive_DataRequest(struct drbd_conf *mdev, struct p_header *h)
                 if (drbd_recv(mdev, di->digest, digest_size) != digest_size)
                         goto out_free_e;
 
-                e->block_id = (u64)(unsigned long)di;
+                e->digest = di;
                 if (h->command == P_CSUM_RS_REQUEST) {
                         D_ASSERT(mdev->agreed_pro_version >= 89);
                         e->w.cb = w_e_end_csum_rs_req;
@@ -3769,6 +3769,7 @@ static void drbd_disconnect(struct drbd_conf *mdev)
         drbd_thread_stop(&mdev->asender);
         drbd_free_sock(mdev);
 
+        /* wait for current activity to cease. */
         spin_lock_irq(&mdev->req_lock);
         _drbd_wait_ee_list_empty(mdev, &mdev->active_ee);
         _drbd_wait_ee_list_empty(mdev, &mdev->sync_ee);
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 30b8e466a224..f979e22cc6fb 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -1018,7 +1018,7 @@ int w_e_end_csum_rs_req(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 
         drbd_rs_complete_io(mdev, e->sector);
 
-        di = (struct digest_info *)(unsigned long)e->block_id;
+        di = e->digest;
 
         if (likely((e->flags & EE_WAS_ERROR) == 0)) {
                 /* quick hack to try to avoid a race against reconfiguration.
@@ -1126,7 +1126,7 @@ int w_e_end_ov_reply(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
          * the resync lru has been cleaned up already */
         drbd_rs_complete_io(mdev, e->sector);
 
-        di = (struct digest_info *)(unsigned long)e->block_id;
+        di = e->digest;
 
         if (likely((e->flags & EE_WAS_ERROR) == 0)) {
                 digest_size = crypto_hash_digestsize(mdev->verify_tfm);