From 413a9572ef0c48a1a34cb3d5dbdd131e1ad37b5e Mon Sep 17 00:00:00 2001
From: Kefu Chai <kchai@redhat.com>
Date: Fri, 7 Aug 2020 18:47:52 +0800
Subject: [PATCH] crimson/osd: support sparse_read op

Signed-off-by: Kefu Chai <kchai@redhat.com>
---
 src/crimson/osd/ops_executer.cc |  4 ++++
 src/crimson/osd/pg_backend.cc   | 31 +++++++++++++++++++++++++++++++
 src/crimson/osd/pg_backend.h    |  3 +++
 3 files changed, 38 insertions(+)

diff --git a/src/crimson/osd/ops_executer.cc b/src/crimson/osd/ops_executer.cc
index 810c557252a94..5d0eaa21a1a96 100644
--- a/src/crimson/osd/ops_executer.cc
+++ b/src/crimson/osd/ops_executer.cc
@@ -691,6 +691,10 @@ OpsExecuter::execute_osd_op(OSDOp& osd_op)
           return osd_op_errorator::now();
         });
     });
+  case CEPH_OSD_OP_SPARSE_READ:
+    return do_read_op([&osd_op] (auto& backend, const auto& os) {
+      return backend.sparse_read(os, osd_op);
+    });
   case CEPH_OSD_OP_CHECKSUM:
     return do_read_op([&osd_op] (auto& backend, const auto& os) {
       return backend.checksum(os, osd_op);
diff --git a/src/crimson/osd/pg_backend.cc b/src/crimson/osd/pg_backend.cc
index e8ad54e29dc0b..72e49451946c6 100644
--- a/src/crimson/osd/pg_backend.cc
+++ b/src/crimson/osd/pg_backend.cc
@@ -216,6 +216,37 @@ PGBackend::read(const object_info_t& oi,
     });
 }
 
+PGBackend::read_errorator::future<>
+PGBackend::sparse_read(const ObjectState& os, OSDOp& osd_op)
+{
+  const auto& op = osd_op.op;
+  logger().trace("sparse_read: {} {}~{}",
+                 os.oi.soid, op.extent.offset, op.extent.length);
+  return store->fiemap(coll, ghobject_t{os.oi.soid},
+		       op.extent.offset,
+		       op.extent.length).then([&os, &osd_op, this](auto&& m) {
+    return seastar::do_with(interval_set<uint64_t>{std::move(m)},
+			    [&os, &osd_op, this](auto&& extents) {
+      return store->readv(coll, ghobject_t{os.oi.soid},
+                          extents, osd_op.op.flags).safe_then(
+        [&os, &osd_op, &extents, this](auto&& bl) -> read_errorator::future<> {
+        if (_read_verify_data(os.oi, bl)) {
+          osd_op.op.extent.length = bl.length();
+          // re-encode since it might be modified
+          ceph::encode(extents, osd_op.outdata);
+          encode_destructively(bl, osd_op.outdata);
+          logger().trace("sparse_read got {} bytes from object {}",
+                         osd_op.op.extent.length, os.oi.soid);
+          return read_errorator::make_ready_future<>();
+        } else {
+          // TODO: repair it if crc mismatches
+          return crimson::ct_error::object_corrupted::make();
+        }
+      });
+    });
+  });
+}
+
 namespace {
 
   template<class CSum>
diff --git a/src/crimson/osd/pg_backend.h b/src/crimson/osd/pg_backend.h
index 67fa12b871658..dab750dde17ff 100644
--- a/src/crimson/osd/pg_backend.h
+++ b/src/crimson/osd/pg_backend.h
@@ -62,6 +62,9 @@ public:
     size_t truncate_size,
     uint32_t truncate_seq,
     uint32_t flags);
+  read_errorator::future<> sparse_read(
+    const ObjectState& os,
+    OSDOp& osd_op);
 
   using checksum_errorator = ll_read_errorator::extend<
     crimson::ct_error::object_corrupted,
-- 
2.39.5