Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 45 insertions, 0 deletions

diff --git a/doc/dev/osd_internals/refcount.rst b/doc/dev/osd_internals/refcount.rst
new file mode 100644
index 000000000..3324b63e5
--- /dev/null
+++ b/doc/dev/osd_internals/refcount.rst
@@ -0,0 +1,45 @@
+========
+Refcount
+========
+
+
+Introduction
+============
+
+Deduplication, as described in ../deduplication.rst, needs a way to
+maintain a target pool of deduplicated chunks with atomic ref
+refcounting.  To that end, there exists an osd object class 
+refcount responsible for using the object class machinery to
+maintain refcounts on deduped chunks and ultimately remove them
+as the refcount hits 0.
+
+Class Interface
+===============
+
+See cls/refcount/cls_refcount_client*
+
+* cls_refcount_get
+
+  Atomically increments the refcount with specified tag ::
+
+    void cls_refcount_get(librados::ObjectWriteOperation& op, const string& tag, bool implicit_ref = false);
+
+* cls_refcount_put
+
+  Atomically decrements the refcount specified by passed tag ::
+
+    void cls_refcount_put(librados::ObjectWriteOperation& op, const string& tag, bool implicit_ref = false);
+
+* cls_refcount_Set
+
+  Atomically sets the set of refcounts with passed list of tags ::
+
+    void cls_refcount_set(librados::ObjectWriteOperation& op, list<string>& refs);
+
+* cls_refcount_read
+
+  Dumps the current set of ref tags for the object ::
+
+    int cls_refcount_read(librados::IoCtx& io_ctx, string& oid, list<string> *refs, bool implicit_ref = false);
+
+