From dc41731fbfd73d9fbb63d3ff360d4c5dd62deaf1 Mon Sep 17 00:00:00 2001
From: Mykola Golub <mgolub@mirantis.com>
Date: Thu, 30 Jun 2016 14:30:08 +0300
Subject: [PATCH] librbd: discard hangs when 'rbd_skip_partial_discard' is
 enabled

Fixes: http://tracker.ceph.com/issues/16386
Signed-off-by: Mykola Golub <mgolub@mirantis.com>
---
 src/librbd/AioImageRequest.cc | 26 ++++++++++++++++++++------
 src/librbd/AioImageRequest.h  |  3 +++
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/src/librbd/AioImageRequest.cc b/src/librbd/AioImageRequest.cc
index 7292978dba550..0c5a916cde04d 100644
--- a/src/librbd/AioImageRequest.cc
+++ b/src/librbd/AioImageRequest.cc
@@ -264,6 +264,8 @@ void AbstractAioImageWrite::send_request() {
                   !m_image_ctx.journal->is_journal_replaying());
   }
 
+  prune_object_extents(object_extents);
+
   if (!object_extents.empty()) {
     uint64_t journal_tid = 0;
     m_aio_comp->set_request_count(
@@ -392,6 +394,24 @@ uint64_t AioImageDiscard::append_journal_event(
   return tid;
 }
 
+void AioImageDiscard::prune_object_extents(ObjectExtents &object_extents) {
+  CephContext *cct = m_image_ctx.cct;
+  if (!cct->_conf->rbd_skip_partial_discard) {
+    return;
+  }
+
+  for (auto p = object_extents.begin(); p != object_extents.end(); ) {
+    if (p->offset + p->length < m_image_ctx.layout.object_size) {
+      ldout(cct, 20) << " oid " << p->oid << " " << p->offset << "~"
+		     << p->length << " from " << p->buffer_extents
+		     << ": skip partial discard" << dendl;
+      p = object_extents.erase(p);
+    } else {
+      ++p;
+    }
+  }
+}
+
 uint32_t AioImageDiscard::get_cache_request_count(bool journaling) const {
   // extra completion request is required for tracking journal commit
   return (m_image_ctx.object_cacher != nullptr && journaling ? 1 : 0);
@@ -415,8 +435,6 @@ void AioImageDiscard::send_cache_requests(const ObjectExtents &object_extents,
 AioObjectRequest *AioImageDiscard::create_object_request(
     const ObjectExtent &object_extent, const ::SnapContext &snapc,
     Context *on_finish) {
-  CephContext *cct = m_image_ctx.cct;
-
   AioObjectRequest *req;
   if (object_extent.length == m_image_ctx.layout.object_size) {
     req = new AioObjectRemove(&m_image_ctx, object_extent.oid.name,
@@ -427,10 +445,6 @@ AioObjectRequest *AioImageDiscard::create_object_request(
                                 object_extent.objectno, object_extent.offset,
                                 snapc, on_finish);
   } else {
-    if(cct->_conf->rbd_skip_partial_discard) {
-      delete on_finish;
-      return NULL;
-    }
     req = new AioObjectZero(&m_image_ctx, object_extent.oid.name,
                             object_extent.objectno, object_extent.offset,
                             object_extent.length, snapc, on_finish);
diff --git a/src/librbd/AioImageRequest.h b/src/librbd/AioImageRequest.h
index c3987a873105e..b3fc754f889aa 100644
--- a/src/librbd/AioImageRequest.h
+++ b/src/librbd/AioImageRequest.h
@@ -113,6 +113,8 @@ protected:
 
   virtual void send_request();
 
+  virtual void prune_object_extents(ObjectExtents &object_extents) {
+  }
   virtual uint32_t get_cache_request_count(bool journaling) const {
     return 0;
   }
@@ -179,6 +181,7 @@ protected:
     return "aio_discard";
   }
 
+  virtual void prune_object_extents(ObjectExtents &object_extents) override;
   virtual uint32_t get_cache_request_count(bool journaling) const override;
   virtual void send_cache_requests(const ObjectExtents &object_extents,
                                    uint64_t journal_tid);
-- 
2.39.5