From ca4f546f63324c74a6aec8d55dd7ca5891a03b84 Mon Sep 17 00:00:00 2001
From: Jason Dillaman <dillaman@redhat.com>
Date: Tue, 20 Oct 2020 13:10:06 -0400
Subject: [PATCH] librbd: remove io::ReadResult::set_clip_length

Combined the functionality with the newer 'set_image_extents' call
to simplify the call-site logic for IO reads.

Signed-off-by: Jason Dillaman <dillaman@redhat.com>
---
 src/librbd/cache/WriteLogImageDispatch.cc |  5 ++---
 src/librbd/io/ImageRequest.cc             |  1 -
 src/librbd/io/ReadResult.cc               | 26 ++++++-----------------
 src/librbd/io/ReadResult.h                |  2 --
 src/librbd/io/Utils.cc                    |  8 -------
 src/librbd/io/Utils.h                     |  8 ++++++-
 6 files changed, 16 insertions(+), 34 deletions(-)

diff --git a/src/librbd/cache/WriteLogImageDispatch.cc b/src/librbd/cache/WriteLogImageDispatch.cc
index 254eb431f5184..bf1831cbacfbd 100644
--- a/src/librbd/cache/WriteLogImageDispatch.cc
+++ b/src/librbd/cache/WriteLogImageDispatch.cc
@@ -63,8 +63,7 @@ bool WriteLogImageDispatch<I>::read(
 
   aio_comp->set_request_count(1);
   aio_comp->read_result = std::move(read_result);
-  uint64_t length = io::util::extents_length(image_extents);
-  aio_comp->read_result.set_clip_length(length);
+  aio_comp->read_result.set_image_extents(image_extents);
 
   auto *req_comp = new io::ReadResult::C_ImageReadRequest(
     aio_comp, image_extents);
@@ -218,7 +217,7 @@ bool WriteLogImageDispatch<I>::list_snaps(
 template <typename I>
 bool WriteLogImageDispatch<I>::preprocess_length(
     io::AioCompletion* aio_comp, io::Extents &image_extents) const {
-  auto total_bytes = io::util::extents_length(image_extents);
+  auto total_bytes = io::util::get_extents_length(image_extents);
   if (total_bytes == 0) {
     aio_comp->set_request_count(0);
     return true;
diff --git a/src/librbd/io/ImageRequest.cc b/src/librbd/io/ImageRequest.cc
index 5f5ea4471ecb3..17b97f9edf870 100644
--- a/src/librbd/io/ImageRequest.cc
+++ b/src/librbd/io/ImageRequest.cc
@@ -403,7 +403,6 @@ void ImageReadRequest<I>::send_request() {
   }
 
   AioCompletion *aio_comp = this->m_aio_comp;
-  aio_comp->read_result.set_clip_length(buffer_ofs);
   aio_comp->read_result.set_image_extents(image_extents);
 
   // issue the requests
diff --git a/src/librbd/io/ReadResult.cc b/src/librbd/io/ReadResult.cc
index 963d4c685accf..d0a1e7e8294a3 100644
--- a/src/librbd/io/ReadResult.cc
+++ b/src/librbd/io/ReadResult.cc
@@ -5,6 +5,7 @@
 #include "include/buffer.h"
 #include "common/dout.h"
 #include "librbd/io/AioCompletion.h"
+#include "librbd/io/Utils.h"
 #include <boost/variant/apply_visitor.hpp>
 #include <boost/variant/static_visitor.hpp>
 
@@ -16,29 +17,20 @@
 namespace librbd {
 namespace io {
 
-struct ReadResult::SetClipLengthVisitor : public boost::static_visitor<void> {
-  size_t length;
+struct ReadResult::SetImageExtentsVisitor : public boost::static_visitor<void> {
+  Extents image_extents;
 
-  explicit SetClipLengthVisitor(size_t length) : length(length) {
+  explicit SetImageExtentsVisitor(const Extents& image_extents)
+    : image_extents(image_extents) {
   }
 
   void operator()(Linear &linear) const {
+    uint64_t length = util::get_extents_length(image_extents);
+
     ceph_assert(length <= linear.buf_len);
     linear.buf_len = length;
   }
 
-  template <typename T>
-  void operator()(T &t) const {
-  }
-};
-
-struct ReadResult::SetImageExtentsVisitor : public boost::static_visitor<void> {
-  Extents image_extents;
-
-  explicit SetImageExtentsVisitor(const Extents& image_extents)
-    : image_extents(image_extents) {
-  }
-
   void operator()(SparseBufferlist &sbl) const {
     sbl.image_extents = image_extents;
   }
@@ -253,10 +245,6 @@ ReadResult::ReadResult(Extents* extent_map, ceph::bufferlist* bl)
   : m_buffer(SparseBufferlist(extent_map, bl)) {
 }
 
-void ReadResult::set_clip_length(size_t length) {
-  boost::apply_visitor(SetClipLengthVisitor(length), m_buffer);
-}
-
 void ReadResult::set_image_extents(const Extents& image_extents) {
   boost::apply_visitor(SetImageExtentsVisitor(image_extents), m_buffer);
 }
diff --git a/src/librbd/io/ReadResult.h b/src/librbd/io/ReadResult.h
index 3a5b0d7bb37b6..69ced0c7b3760 100644
--- a/src/librbd/io/ReadResult.h
+++ b/src/librbd/io/ReadResult.h
@@ -63,7 +63,6 @@ public:
   ReadResult(ceph::bufferlist *bl);
   ReadResult(Extents* extent_map, ceph::bufferlist* bl);
 
-  void set_clip_length(size_t length);
   void set_image_extents(const Extents& image_extents);
 
   void assemble_result(CephContext *cct);
@@ -112,7 +111,6 @@ private:
                          Vector,
                          Bufferlist,
                          SparseBufferlist> Buffer;
-  struct SetClipLengthVisitor;
   struct SetImageExtentsVisitor;
   struct AssembleResultVisitor;
 
diff --git a/src/librbd/io/Utils.cc b/src/librbd/io/Utils.cc
index bc5f9644ff9e6..bfb89cfecc37b 100644
--- a/src/librbd/io/Utils.cc
+++ b/src/librbd/io/Utils.cc
@@ -151,14 +151,6 @@ int clip_request(I *image_ctx, Extents *image_extents) {
   return 0;
 }
 
-uint64_t extents_length(Extents &extents) {
-  uint64_t total_bytes = 0;
-  for (auto& image_extent : extents) {
-    total_bytes += image_extent.second;
-  }
-  return total_bytes;
-}
-
 void unsparsify(CephContext* cct, ceph::bufferlist* bl,
                 const Extents& extent_map, uint64_t bl_off,
                 uint64_t out_bl_len) {
diff --git a/src/librbd/io/Utils.h b/src/librbd/io/Utils.h
index c58649bb975db..d28786b2a3d79 100644
--- a/src/librbd/io/Utils.h
+++ b/src/librbd/io/Utils.h
@@ -37,7 +37,13 @@ void read_parent(ImageCtxT *image_ctx, uint64_t object_no,
 template <typename ImageCtxT = librbd::ImageCtx>
 int clip_request(ImageCtxT *image_ctx, Extents *image_extents);
 
-uint64_t extents_length(Extents &extents);
+inline uint64_t get_extents_length(const Extents &extents) {
+  uint64_t total_bytes = 0;
+  for (auto [_, extent_length] : extents) {
+    total_bytes += extent_length;
+  }
+  return total_bytes;
+}
 
 void unsparsify(CephContext* cct, ceph::bufferlist* bl,
                 const Extents& extent_map, uint64_t bl_off,
-- 
2.39.5