From: Mykola Golub <mgolub@suse.com>
Date: Wed, 14 Mar 2018 12:11:56 +0000 (+0200)
Subject: librbd: add function to wait writes unblocked
X-Git-Tag: v14.0.1~590^2~25
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=eed5415aec555adc397e91ef2810a913f9c4e628;p=ceph.git

librbd: add function to wait writes unblocked

Signed-off-by: Mykola Golub <mgolub@suse.com>
---

diff --git a/src/librbd/io/ImageRequestWQ.cc b/src/librbd/io/ImageRequestWQ.cc
index cbcdf1010ab9..2c87e606a209 100644
--- a/src/librbd/io/ImageRequestWQ.cc
+++ b/src/librbd/io/ImageRequestWQ.cc
@@ -540,6 +540,7 @@ void ImageRequestWQ<I>::unblock_writes() {
   CephContext *cct = m_image_ctx.cct;
 
   bool wake_up = false;
+  Contexts waiter_contexts;
   {
     RWLock::WLocker locker(m_lock);
     assert(m_write_blockers > 0);
@@ -549,14 +550,36 @@ void ImageRequestWQ<I>::unblock_writes() {
                   << m_write_blockers << dendl;
     if (m_write_blockers == 0) {
       wake_up = true;
+      std::swap(waiter_contexts, m_unblocked_write_waiter_contexts);
     }
   }
 
   if (wake_up) {
+    for (auto ctx : waiter_contexts) {
+      ctx->complete(0);
+    }
     this->signal();
   }
 }
 
+template <typename I>
+void ImageRequestWQ<I>::wait_on_writes_unblocked(Context *on_unblocked) {
+  assert(m_image_ctx.owner_lock.is_locked());
+  CephContext *cct = m_image_ctx.cct;
+
+  {
+    RWLock::WLocker locker(m_lock);
+    ldout(cct, 20) << &m_image_ctx << ", " << "write_blockers="
+                   << m_write_blockers << dendl;
+    if (!m_unblocked_write_waiter_contexts.empty() || m_write_blockers > 0) {
+      m_unblocked_write_waiter_contexts.push_back(on_unblocked);
+      return;
+    }
+  }
+
+  on_unblocked->complete(0);
+}
+
 template <typename I>
 void ImageRequestWQ<I>::set_require_lock(Direction direction, bool enabled) {
   CephContext *cct = m_image_ctx.cct;
diff --git a/src/librbd/io/ImageRequestWQ.h b/src/librbd/io/ImageRequestWQ.h
index 87e5198da63c..ebb0c4bd305e 100644
--- a/src/librbd/io/ImageRequestWQ.h
+++ b/src/librbd/io/ImageRequestWQ.h
@@ -69,6 +69,8 @@ public:
   void block_writes(Context *on_blocked);
   void unblock_writes();
 
+  void wait_on_writes_unblocked(Context *on_unblocked);
+
   void set_require_lock(Direction direction, bool enabled);
 
   void apply_qos_limit(uint64_t limit, const uint64_t flag);
@@ -93,6 +95,7 @@ private:
   mutable RWLock m_lock;
   Contexts m_write_blocker_contexts;
   uint32_t m_write_blockers = 0;
+  Contexts m_unblocked_write_waiter_contexts;
   bool m_require_lock_on_read = false;
   bool m_require_lock_on_write = false;
   std::atomic<unsigned> m_queued_reads { 0 };