From e5f2bb080e401da89e9d33cdc9d7cd021be726d5 Mon Sep 17 00:00:00 2001
From: Jason Dillaman <dillaman@redhat.com>
Date: Tue, 15 Mar 2016 15:26:05 -0400
Subject: [PATCH] librbd: initial implementation of mirror image promote/demote

Signed-off-by: Jason Dillaman <dillaman@redhat.com>
---
 src/librbd/internal.cc | 85 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 83 insertions(+), 2 deletions(-)

diff --git a/src/librbd/internal.cc b/src/librbd/internal.cc
index 0dd1fd33ac24..8b10bd1bcdb9 100644
--- a/src/librbd/internal.cc
+++ b/src/librbd/internal.cc
@@ -183,6 +183,23 @@ int validate_pool(IoCtx &io_ctx, CephContext *cct) {
   return 0;
 }
 
+int validate_mirroring_enabled(ImageCtx *ictx) {
+  CephContext *cct = ictx->cct;
+  cls::rbd::MirrorImage mirror_image_internal;
+  int r = cls_client::mirror_image_get(&ictx->md_ctx, ictx->id,
+      &mirror_image_internal);
+  if (r < 0 && r != -ENOENT) {
+    lderr(cct) << "failed to retrieve mirroring state: " << cpp_strerror(r)
+      << dendl;
+    return r;
+  } else if (mirror_image_internal.state !=
+               cls::rbd::MirrorImageState::MIRROR_IMAGE_STATE_ENABLED) {
+    lderr(cct) << "mirroring is not currently enabled" << dendl;
+    return -EINVAL;
+  }
+  return 0;
+}
+
 } // anonymous namespace
 
   int detect_format(IoCtx &io_ctx, const string &name,
@@ -2487,13 +2504,77 @@ int validate_pool(IoCtx &io_ctx, CephContext *cct) {
     CephContext *cct = ictx->cct;
     ldout(cct, 20) << __func__ << ": ictx=" << ictx << ", "
                    << "force=" << force << dendl;
-    return -EOPNOTSUPP;
+
+    int r = validate_mirroring_enabled(ictx);
+    if (r < 0) {
+      return r;
+    }
+
+    std::string mirror_uuid;
+    r = Journal<>::get_tag_owner(ictx, &mirror_uuid);
+    if (r < 0) {
+      lderr(cct) << "failed to determine tag ownership: " << cpp_strerror(r)
+                 << dendl;
+      return r;
+    } else if (mirror_uuid == Journal<>::LOCAL_MIRROR_UUID) {
+      lderr(cct) << "image is already primary" << dendl;
+      return -EINVAL;
+    } else if (mirror_uuid != Journal<>::ORPHAN_MIRROR_UUID && !force) {
+      lderr(cct) << "image is still primary within a remote cluster" << dendl;
+      return -EBUSY;
+    }
+
+    // TODO: need interlock with local rbd-mirror daemon to ensure it has stopped
+    //       replay
+
+    r = Journal<>::allocate_tag(ictx, Journal<>::LOCAL_MIRROR_UUID);
+    if (r < 0) {
+      lderr(cct) << "failed to promote image: " << cpp_strerror(r)
+                 << dendl;
+      return r;
+    }
+    return 0;
   }
 
   int mirror_image_demote(ImageCtx *ictx) {
     CephContext *cct = ictx->cct;
     ldout(cct, 20) << __func__ << ": ictx=" << ictx << dendl;
-    return -EOPNOTSUPP;
+
+    int r = validate_mirroring_enabled(ictx);
+    if (r < 0) {
+      return r;
+    }
+
+    bool is_primary;
+    r = Journal<>::is_tag_owner(ictx, &is_primary);
+    if (r < 0) {
+      lderr(cct) << "failed to determine tag ownership: " << cpp_strerror(r)
+                 << dendl;
+      return r;
+    }
+
+    if (!is_primary) {
+      lderr(cct) << "image is not currently the primary" << dendl;
+      return -EINVAL;
+    }
+
+    RWLock::RLocker owner_lock(ictx->owner_lock);
+    C_SaferCond lock_ctx;
+    ictx->exclusive_lock->request_lock(&lock_ctx);
+    r = lock_ctx.wait();
+    if (r < 0) {
+      lderr(cct) << "failed to lock image: " << cpp_strerror(r) << dendl;
+    } else if (!ictx->exclusive_lock->is_lock_owner()) {
+      lderr(cct) << "failed to acquire exclusive lock" << dendl;
+    }
+
+    r = Journal<>::allocate_tag(ictx, Journal<>::ORPHAN_MIRROR_UUID);
+    if (r < 0) {
+      lderr(cct) << "failed to demote image: " << cpp_strerror(r)
+                 << dendl;
+      return r;
+    }
+    return 0;
   }
 
   int mirror_image_resync(ImageCtx *ictx) {
-- 
2.47.3