osd: Correct truncate logic for new EC

The clone logic in the truncate was only cloning from the truncate
to the end of the pre-truncate object. If the next shard was being
truncated to a shorter length (which is common), then this shard
has a larger clone.

The rollback, however, can only be given a single range, so it was
given a range which covers all clones.  The problem is that if shard
0 is rolled back, then some empty space from the clone was copied
to shard 0.

Fix is easy - calculate the full clone length and apply to all shards, so it matches the rollback.

Signed-off-by: Alex Ainscow <aainscow@uk.ibm.com>
(cherry picked from commit 5d7588c051b31098c9970877ab6a784967ff94c8)

diff --git a/src/osd/ECTransaction.cc b/src/osd/ECTransaction.cc
index 6486e89521df37c7ce5c09bf329e5f69ea4b945b..2c5b0fe3ea085411fa687fde80e39ad55c9a3f25 100644 (file)
--- a/src/osd/ECTransaction.cc
+++ b/src/osd/ECTransaction.cc
@@ -37,12 +37,14 @@ using ceph::ErasureCodeInterfaceRef;
 void debug(const hobject_t &oid, const std::string &str,
            const ECUtil::shard_extent_map_t &map, DoutPrefixProvider *dpp) {
   ldpp_dout(dpp, 20)
-    << " generate_transactions: " << "oid: " << oid << str << map << dendl;
+    << " generate_transactions: " << "oid: " << oid << " " << str << " " << map << dendl;
   ldpp_dout(dpp, 20)
     << "EC_DEBUG_BUFFERS: " << map.debug_string(2048, 0) << dendl;
 }
 
 void ECTransaction::Generate::encode_and_write() {
+  ldpp_dout(dpp, 20)<< __func__ << dendl;
+
   // For PDW, we already have necessary parity buffers.
   if (!plan.do_parity_delta_write) {
     to_write.insert_parity_buffers();
@@ -625,17 +627,29 @@ void ECTransaction::Generate::truncate() {
     uint64_t clone_start = std::numeric_limits<uint64_t>::max();
     uint64_t clone_end = 0;
 
-    shard_id_set clone_shards; // intentionally left blank!
+    shard_id_set clone_shards;
 
     for (auto &&[shard, eset]: truncate_eset) {
       clone_shards.insert(shard);
+      uint64_t start = eset.range_start();
+      uint64_t start_align_prev = ECUtil::align_prev(start);
+      uint64_t end = eset.range_end();
+
+      if (clone_start > start_align_prev) {
+        clone_start = start_align_prev;
+      }
+      if (clone_end < end) {
+        clone_end = end;
+      }
+    }
+
+    for (auto &&[shard, eset]: truncate_eset) {
       if (!transactions.contains(shard)) {
         continue;
       }
 
       auto &t = transactions.at(shard);
       uint64_t start = eset.range_start();
-      uint64_t start_align_prev = ECUtil::align_prev(start);
       uint64_t start_align_next = ECUtil::align_next(start);
       uint64_t end = eset.range_end();
       t.touch(
@@ -645,9 +659,9 @@ void ECTransaction::Generate::truncate() {
         coll_t(spg_t(pgid, shard)),
         ghobject_t(oid, ghobject_t::NO_GEN, shard),
         ghobject_t(oid, entry->version.version, shard),
-        start_align_prev,
-        end - start_align_prev,
-        start_align_prev);
+        clone_start,
+        end - clone_start,
+        clone_start);
 
       // First truncate to exactly the right size.
       t.truncate(
@@ -664,21 +678,15 @@ void ECTransaction::Generate::truncate() {
           ghobject_t(oid, ghobject_t::NO_GEN, shard),
           start_align_next);
       }
-
-      if (clone_start > start_align_prev) {
-        clone_start = start_align_prev;
-      }
-      if (clone_end < end) {
-        clone_end = end;
-      }
     }
-    shards_written(clone_shards);
-    rollback_extents.emplace_back(make_pair(clone_start, clone_end));
+    rollback_extents.emplace_back(make_pair(clone_start, clone_end - clone_start));
     rollback_shards.emplace_back(clone_shards);
   }
 }
 
 void ECTransaction::Generate::overlay_writes() {
+  ldpp_dout(dpp, 20) << __func__ << " start " << dendl;
+
   for (auto &&extent: op.buffer_updates) {
     using BufferUpdate = PGTransaction::ObjectOperation::BufferUpdate;
     bufferlist bl;
@@ -708,6 +716,7 @@ void ECTransaction::Generate::appends_and_clone_ranges() {
 
   extent_set clone_ranges = plan.will_write.get_extent_superset();
   uint64_t clone_max = ECUtil::align_next(plan.orig_size);
+  ldpp_dout(dpp, 20) << __func__ << dendl;
 
   if (op.delete_first) {
     clone_max = 0;