crimson/osd: remove osd_op_params_t::user_at_version

osd_op_params_t::user_at_version was populated from
osd_op_params_t::at_version before the call to prepare_transaction,
which incremented osd_op_params_t::at_version.version.  As a result,
the value stored in object_info_t::user_version ended up one version
behind object_info_t::version.  The log entry, on the other hand,
ended up with the correct version as OpsExecutor::prepare_transaction
populates it directly from at_version.  As a result, the primary could
return different versions to the client depending on whether the IO was
already in the log.

This commit eliminates osd_op_params_t::user_at_version and updates
PGBackend::mutate_object to behave like prepare_transaction.  Because
the prior commit removes the prepare_transaction increment, this isn't
strictly necessary, but it is simpler.

Fixes: https://tracker.ceph.com/issues/65857
Signed-off-by: Samuel Just <[email protected]>

src/crimson/osd/ops_executer.h

@@ -520,9 +520,6 @@ OpsExecuter::flush_changes_n_do_ops_effects(
     ceph_assert(want_mutate);
   }
   if (want_mutate) {
-    if (osd_op_params->user_modify) {
-      osd_op_params->user_at_version = osd_op_params->at_version.version;
-    }
     maybe_mutated = flush_clone_metadata(
       prepare_transaction(ops),
       snap_mapper,

src/crimson/osd/osd_operations/osdop_params.h

@@ -14,7 +14,6 @@ struct osd_op_params_t {
   eversion_t pg_trim_to;
   eversion_t min_last_complete_ondisk;
   eversion_t last_complete;
-  version_t user_at_version = 0;
   bool user_modify = false;
   ObjectCleanRegions clean_regions;
   interval_set<uint64_t> modified_ranges;

src/crimson/osd/pg_backend.cc

@@ -165,8 +165,8 @@ PGBackend::mutate_object(
   if (obc->obs.exists) {
     obc->obs.oi.prior_version = obc->obs.oi.version;
     obc->obs.oi.version = osd_op_p.at_version;
-    if (osd_op_p.user_at_version > obc->obs.oi.user_version)
-      obc->obs.oi.user_version = osd_op_p.user_at_version;
+    if (osd_op_p.user_modify)
+      obc->obs.oi.user_version = osd_op_p.at_version.version;
     obc->obs.oi.last_reqid = osd_op_p.req_id;
     obc->obs.oi.mtime = osd_op_p.mtime;
     obc->obs.oi.local_mtime = ceph_clock_now();