librbd/migration: add support for reading from QCOW2 snapshots

Tweak the IO read path to now utilize the L1 table associated with
the specified snapshot id. This will cause the IO to properly read
from the specific snapshot.

Signed-off-by: Jason Dillaman <dillaman@redhat.com>

diff --git a/qa/workunits/rbd/cli_migration.sh b/qa/workunits/rbd/cli_migration.sh
index 42ef5655e9666abe3ab7f4f5fcace5b01bd2c0ab..1fafbabe3616ed62cef44e2952721b3dcbf7c6a0 100755 (executable)
--- a/qa/workunits/rbd/cli_migration.sh
+++ b/qa/workunits/rbd/cli_migration.sh
@@ -195,7 +195,27 @@ test_import_qcow2_format() {
     local base_image=$1
     local dest_image=$2
 
-    qemu-img convert -f raw -O qcow2 rbd:rbd/${base_image} ${TEMPDIR}/${base_image}.qcow2
+    # create new image via qemu-img and its bench tool since we cannot
+    # import snapshot deltas into QCOW2
+    qemu-img create -f qcow2 ${TEMPDIR}/${base_image}.qcow2 1G
+
+    qemu-img bench -f qcow2 -w -c 65536 -d 16 --pattern 65 -s 4096 \
+        -S $((($RANDOM % 262144) * 4096)) ${TEMPDIR}/${base_image}.qcow2
+    qemu-img convert -f qcow2 -O raw ${TEMPDIR}/${base_image}.qcow2 \
+        "${TEMPDIR}/${base_image}@snap1"
+    qemu-img snapshot -c "snap1" ${TEMPDIR}/${base_image}.qcow2
+
+    qemu-img bench -f qcow2 -w -c 16384 -d 16 --pattern 66 -s 4096 \
+        -S $((($RANDOM % 262144) * 4096)) ${TEMPDIR}/${base_image}.qcow2
+    qemu-img convert -f qcow2 -O raw ${TEMPDIR}/${base_image}.qcow2 \
+        "${TEMPDIR}/${base_image}@snap2"
+    qemu-img snapshot -c "snap2" ${TEMPDIR}/${base_image}.qcow2
+
+    qemu-img bench -f qcow2 -w -c 32768 -d 16 --pattern 67 -s 4096 \
+        -S $((($RANDOM % 262144) * 4096)) ${TEMPDIR}/${base_image}.qcow2
+    qemu-img convert -f qcow2 -O raw ${TEMPDIR}/${base_image}.qcow2 \
+        ${TEMPDIR}/${base_image}
+
     qemu-img info -f qcow2 ${TEMPDIR}/${base_image}.qcow2
 
     cat > ${TEMPDIR}/spec.json <<EOF
@@ -212,6 +232,8 @@ EOF
     rbd migration prepare --import-only \
         --source-spec-path ${TEMPDIR}/spec.json ${dest_image}
 
+    compare_images "${base_image}@snap1" "${dest_image}@snap1"
+    compare_images "${base_image}@snap2" "${dest_image}@snap2"
     compare_images "${base_image}" "${dest_image}"
 
     rbd migration abort ${dest_image}
@@ -219,6 +241,8 @@ EOF
     rbd migration prepare --import-only \
         --source-spec-path ${TEMPDIR}/spec.json ${dest_image}
 
+    compare_images "${base_image}@snap1" "${dest_image}@snap1"
+    compare_images "${base_image}@snap2" "${dest_image}@snap2"
     compare_images "${base_image}" "${dest_image}"
 
     rbd migration execute ${dest_image}
@@ -320,7 +344,7 @@ export_base_image ${IMAGE1}
 
 test_import_native_format ${IMAGE1} ${IMAGE2}
 test_import_qcow_format ${IMAGE1} ${IMAGE2}
-test_import_qcow2_format ${IMAGE1} ${IMAGE2}
+test_import_qcow2_format ${IMAGE2} ${IMAGE3}
 test_import_raw_format ${IMAGE1} ${IMAGE2}
 
 echo OK

diff --git a/src/librbd/migration/QCOWFormat.cc b/src/librbd/migration/QCOWFormat.cc
index 4fade6472631e0bb81ec594a4ca5f88a4976df7b..2c75859b3bd35f7208047ef66241daf8bec2b52b 100644 (file)
--- a/src/librbd/migration/QCOWFormat.cc
+++ b/src/librbd/migration/QCOWFormat.cc
@@ -241,15 +241,17 @@ public:
       l2_cache_entries(QCOW_L2_CACHE_SIZE) {
   }
 
-  void get_cluster_offset(uint64_t image_offset, uint64_t* cluster_offset,
+  void get_cluster_offset(uint32_t l1_size, const uint64_t* l1_table,
+                          uint64_t image_offset, uint64_t* cluster_offset,
                           Context* on_finish) {
     auto cct = qcow_format->m_image_ctx->cct;
     ldout(cct, 20) << "image_offset=" << image_offset << dendl;
 
     // cache state machine runs in a single strand thread
+    Request request{l1_size, l1_table, image_offset, cluster_offset, on_finish};
     boost::asio::dispatch(
-      m_strand, [this, image_offset, cluster_offset, on_finish]() {
-        requests.emplace_back(image_offset, cluster_offset, on_finish);
+      m_strand, [this, request=std::move(request)]() {
+        requests.push_back(std::move(request));
       });
     dispatch_get_cluster_offset();
   }
@@ -262,13 +264,17 @@ private:
   boost::asio::io_context::strand m_strand;
 
   struct Request {
+    uint32_t l1_size;
+    const uint64_t* l1_table;
+
     uint64_t image_offset;
     uint64_t* cluster_offset;
     Context* on_finish;
 
-    Request(uint64_t image_offset, uint64_t* cluster_offset, Context* on_finish)
-      : image_offset(image_offset), cluster_offset(cluster_offset),
-        on_finish(on_finish) {
+    Request(uint32_t l1_size, const uint64_t* l1_table, uint64_t image_offset,
+            uint64_t* cluster_offset, Context* on_finish)
+      : l1_size(l1_size), l1_table(l1_table), image_offset(image_offset),
+        cluster_offset(cluster_offset), on_finish(on_finish) {
     }
   };
   typedef std::deque<Request> Requests;
@@ -300,7 +306,8 @@ private:
     auto request = requests.front();
     auto l1_index = request.image_offset >>
                     (l2_bits + qcow_format->m_cluster_bits);
-    auto l2_offset = qcow_format->m_l1_table[l1_index] &
+    auto l2_offset = request.l1_table[
+                       std::min<uint32_t>(l1_index, request.l1_size - 1)] &
                      qcow_format->m_cluster_mask;
     auto l2_index = (request.image_offset >> qcow_format->m_cluster_bits) &
                     (l2_size - 1);
@@ -310,7 +317,10 @@ private:
                    << "l2_index=" << l2_index << dendl;
 
     int r = 0;
-    if (l2_offset == 0) {
+    if (l1_index >= request.l1_size) {
+      lderr(cct) << "L1 index " << l1_index << " out-of-bounds" << dendl;
+      r = -ERANGE;
+    } else if (l2_offset == 0) {
       // L2 table has not been allocated for specified offset
       ldout(cct, 20) << "image_offset=" << request.image_offset << ", "
                      << "cluster_offset=DNE" << dendl;
@@ -459,9 +469,10 @@ template <typename I>
 class QCOWFormat<I>::ReadRequest {
 public:
   ReadRequest(QCOWFormat* qcow_format, io::AioCompletion* aio_comp,
+              uint32_t l1_size, const uint64_t* l1_table,
               io::Extents&& image_extents)
-    : qcow_format(qcow_format), aio_comp(aio_comp),
-      image_extents(std::move(image_extents)) {
+    : qcow_format(qcow_format), aio_comp(aio_comp), l1_size(l1_size),
+      l1_table(l1_table), image_extents(std::move(image_extents)) {
   }
 
   void send() {
@@ -472,7 +483,10 @@ private:
   QCOWFormat* qcow_format;
   io::AioCompletion* aio_comp;
 
+  uint32_t l1_size;
+  const uint64_t* l1_table;
   io::Extents image_extents;
+
   size_t image_extents_idx = 0;
   uint32_t image_extent_offset = 0;
 
@@ -493,7 +507,8 @@ private:
         [this, &cluster_extent, on_finish=gather_ctx->new_sub()](int r) {
           handle_get_cluster_offset(r, cluster_extent, on_finish); });
       qcow_format->m_l2_table_cache->get_cluster_offset(
-        cluster_extent.image_offset, &cluster_extent.cluster_offset, sub_ctx);
+        l1_size, l1_table, cluster_extent.image_offset,
+        &cluster_extent.cluster_offset, sub_ctx);
     }
 
     gather_ctx->activate();
@@ -592,9 +607,11 @@ private:
 template <typename I>
 class QCOWFormat<I>::ListSnapsRequest {
 public:
-  ListSnapsRequest(QCOWFormat* qcow_format, io::Extents&& image_extents,
+  ListSnapsRequest(QCOWFormat* qcow_format, uint32_t l1_size,
+                   const uint64_t* l1_table, io::Extents&& image_extents,
                    io::SparseExtents* sparse_extents, Context* on_finish)
-    : qcow_format(qcow_format), image_extents(std::move(image_extents)),
+    : qcow_format(qcow_format), l1_size(l1_size),
+      l1_table(l1_table), image_extents(std::move(image_extents)),
       sparse_extents(sparse_extents), on_finish(on_finish) {
   }
 
@@ -604,6 +621,8 @@ public:
 
 private:
   QCOWFormat* qcow_format;
+  uint32_t l1_size;
+  const uint64_t* l1_table;
   io::Extents image_extents;
   io::SparseExtents* sparse_extents;
   Context* on_finish;
@@ -630,7 +649,8 @@ private:
             });
         });
       qcow_format->m_l2_table_cache->get_cluster_offset(
-        cluster_extent.image_offset, &cluster_extent.cluster_offset, ctx);
+        l1_size, l1_table, cluster_extent.image_offset,
+        &cluster_extent.cluster_offset, ctx);
     }
 
     gather_ctx->activate();
@@ -1256,17 +1276,28 @@ bool QCOWFormat<I>::read(
   ldout(cct, 20) << "snap_id=" << snap_id << ", "
                  << "image_extents=" << image_extents << dendl;
 
-  if (snap_id != CEPH_NOSNAP) {
-    // TODO add QCOW2 snapshot support
-    lderr(cct) << "snapshots are not supported" << dendl;
-    aio_comp->fail(-EINVAL);
-    return true;
+  uint32_t l1_size;
+  uint64_t* l1_table;
+  if (snap_id == CEPH_NOSNAP) {
+    l1_size = m_l1_size;
+    l1_table = m_l1_table;
+  } else {
+    auto snapshot_it = m_snapshots.find(snap_id);
+    if (snapshot_it == m_snapshots.end()) {
+      aio_comp->fail(-ENOENT);
+      return true;
+    }
+
+    auto& snapshot = snapshot_it->second;
+    l1_size = snapshot.l1_size;
+    l1_table = snapshot.l1_table;
   }
 
   aio_comp->read_result = std::move(read_result);
   aio_comp->read_result.set_image_extents(image_extents);
 
-  auto read_request = new ReadRequest(this, aio_comp, std::move(image_extents));
+  auto read_request = new ReadRequest(this, aio_comp, l1_size, l1_table,
+                                      std::move(image_extents));
   read_request->send();
 
   return true;
@@ -1286,7 +1317,8 @@ void QCOWFormat<I>::list_snaps(io::Extents&& image_extents,
   // QCOW does support snapshots so just use cluster existence for delta
   auto snapshot = &(*snapshot_delta)[{CEPH_NOSNAP, CEPH_NOSNAP}];
   auto list_snaps_request = new ListSnapsRequest(
-    this, io::Extents{image_extents}, snapshot, on_finish);
+    this, m_l1_size, m_l1_table, io::Extents{image_extents}, snapshot,
+    on_finish);
   list_snaps_request->send();
 }