Return version number from reads

blockstore.cpp

@@ -40,7 +40,7 @@ void blockstore_t::enqueue_op_first(blockstore_op_t *op)
     impl->enqueue_op(op, true);
 }
 
-std::map<object_id, uint64_t> & blockstore_t::get_unstable_writes()
+std::unordered_map<object_id, uint64_t> & blockstore_t::get_unstable_writes()
 {
     return impl->unstable_writes;
 }

blockstore.h

@@ -55,8 +55,15 @@ struct blockstore_op_t
     std::function<void (blockstore_op_t*)> callback;
     // For reads, writes & deletes: oid is the requested object
     object_id oid;
-    // For reads: version=0 -> last stable, version=UINT64_MAX -> last unstable, version=X -> specific version
-    // For writes & deletes: a new version is assigned automatically
+    // For reads:
+    //   version == 0 -> read the last stable version,
+    //   version == UINT64_MAX -> read the last version,
+    //   otherwise -> read the newest version that is <= the specified version
+    //   after execution, version is equal to the version that was read from the blockstore
+    // For writes & deletes:
+    //   if version == 0, a new version is assigned automatically
+    //   if version != 0, it is assigned for the new write if possible, otherwise -EINVAL is returned
+    //   after execution, version is equal to the version that was written to the blockstore
     uint64_t version;
     // For reads & writes: offset & len are the requested part of the object, buf is the buffer
     uint32_t offset;
@@ -102,7 +109,7 @@ public:
     void enqueue_op_first(blockstore_op_t *op);
 
     // Unstable writes are added here (map of object_id -> version)
-    std::map<object_id, uint64_t> & get_unstable_writes();
+    std::unordered_map<object_id, uint64_t> & get_unstable_writes();
 
     // FIXME rename to object_size
     uint32_t get_block_size();

blockstore_impl.h

@@ -309,7 +309,7 @@ public:
     void enqueue_op(blockstore_op_t *op, bool first = false);
 
     // Unstable writes are added here (map of object_id -> version)
-    std::map<object_id, uint64_t> unstable_writes;
+    std::unordered_map<object_id, uint64_t> unstable_writes;
 
     inline uint32_t get_block_size() { return block_size; }
     inline uint64_t get_block_count() { return block_count; }

blockstore_read.cpp

@@ -92,12 +92,14 @@ int blockstore_impl_t::dequeue_read(blockstore_op_t *read_op)
     {
         // region is not allocated - return zeroes
         memset(read_op->buf, 0, read_op->len);
+        read_op->version = 0;
         read_op->retval = read_op->len;
         read_op->callback(read_op);
         return 1;
     }
     uint64_t fulfilled = 0;
     PRIV(read_op)->pending_ops = 0;
+    uint64_t result_version = 0;
     if (dirty_found)
     {
         while (dirty_it->first.oid == read_op->oid)
@@ -112,6 +114,10 @@ int blockstore_impl_t::dequeue_read(blockstore_op_t *read_op)
             }
             if (version_ok)
             {
+                if (!result_version)
+                {
+                    result_version = dirty_it->first.version;
+                }
                 if (!fulfill_read(read_op, fulfilled, dirty.offset, dirty.offset + dirty.len,
                     dirty.state, dirty_it->first.version, dirty.location + (IS_JOURNAL(dirty.state) ? 0 : dirty.offset)))
                 {
@@ -129,6 +135,10 @@ int blockstore_impl_t::dequeue_read(blockstore_op_t *read_op)
     }
     if (clean_it != clean_db.end() && fulfilled < read_op->len)
     {
+        if (!result_version)
+        {
+            result_version = clean_it->second.version;
+        }
         if (!clean_entry_bitmap_size)
         {
             if (!fulfill_read(read_op, fulfilled, 0, block_size, ST_CURRENT, 0, clean_it->second.location))
@@ -190,6 +200,7 @@ int blockstore_impl_t::dequeue_read(blockstore_op_t *read_op)
         fulfill_read(read_op, fulfilled, 0, block_size, ST_DEL_STABLE, 0, 0);
     }
     assert(fulfilled == read_op->len);
+    read_op->version = result_version;
     if (!PRIV(read_op)->pending_ops)
     {
         // everything is fulfilled from memory

osd_exec_secondary.cpp

@@ -146,7 +146,8 @@ void osd_t::make_reply(osd_op_t *op)
         op->reply.hdr.retval = op->bs_op.retval;
         if (op->op.hdr.opcode == OSD_OP_SECONDARY_LIST)
             op->reply.sec_list.stable_count = op->bs_op.version;
-        else if (op->op.hdr.opcode == OSD_OP_SECONDARY_WRITE)
+        else if (op->op.hdr.opcode == OSD_OP_SECONDARY_READ ||
+            op->op.hdr.opcode == OSD_OP_SECONDARY_WRITE)
             op->reply.sec_rw.version = op->bs_op.version;
         else if (op->op.hdr.opcode == OSD_OP_SECONDARY_DELETE)
             op->reply.sec_del.version = op->bs_op.version;

osd_ops.h

@@ -69,7 +69,7 @@ struct __attribute__((__packed__)) osd_op_secondary_rw_t
 struct __attribute__((__packed__)) osd_reply_secondary_rw_t
 {
     osd_reply_header_t header;
-    // for writes: assigned version number
+    // for reads and writes: assigned or read version number
     uint64_t version;
 };