Fix slow & failing CAS layer merge

src/client/cluster_client.cpp

@@ -77,11 +77,6 @@ cluster_client_t::~cluster_client_t()
 
 cluster_op_t::~cluster_op_t()
 {
-    if (buf)
-    {
-        free(buf);
-        buf = NULL;
-    }
     if (bitmap_buf)
     {
         free(bitmap_buf);
@@ -570,6 +565,14 @@ void cluster_client_t::execute_internal(cluster_op_t *op)
 {
     op->cur_inode = op->inode;
     op->retval = 0;
+    op->state = 0;
+    op->retry_after = 0;
+    op->inflight_count = 0;
+    op->done_count = 0;
+    op->part_bitmaps = NULL;
+    op->bitmap_buf_size = 0;
+    op->prev_wait = 0;
+    assert(!op->prev && !op->next);
     // check alignment, readonly flag and so on
     if (!check_rw(op))
     {
@@ -1210,7 +1213,9 @@ void cluster_client_t::handle_op_part(cluster_op_part_t *part)
         // So do all these things after modifying operation state, otherwise we may hit reenterability bugs
         // FIXME postpone such things to set_immediate here to avoid bugs
         // Set op->retry_after to retry operation after a short pause (not immediately)
-        if (!op->retry_after)
+        if (!op->retry_after && (op->retval == -EPIPE ||
+            op->retval == -EIO && client_eio_retry_interval ||
+            op->retval == -ENOSPC && client_retry_enospc))
         {
             op->retry_after = op->retval != -EPIPE ? client_eio_retry_interval : client_retry_interval;
         }

src/client/cluster_client.h

@@ -56,8 +56,6 @@ struct cluster_op_t
 protected:
     int state = 0;
     uint64_t cur_inode; // for snapshot reads
-    void *buf = NULL;
-    cluster_op_t *orig_op = NULL;
     bool needs_reslice = false;
     int retry_after = 0;
     int inflight_count = 0, done_count = 0;

src/cmd/cli_merge.cpp

@@ -479,10 +479,14 @@ struct snap_merger_t
         {
             if (op->retval != op->len)
             {
-                rwo->error_code = -op->retval;
+                rwo->error_code = op->retval;
                 rwo->error_offset = op->offset;
                 rwo->error_read = true;
             }
+            else
+            {
+                rwo->error_code = 0;
+            }
             continue_rwo.push_back(rwo);
             parent->ringloop->wakeup();
         };
@@ -553,12 +557,15 @@ struct snap_merger_t
                 if (use_cas && subop->retval == -EINTR)
                 {
                     // CAS failure - reread and repeat optimistically
+                    assert(rwo->todo == 1); // initial refcount from read_and_write
+                    rwo->error_code = -EINTR;
                     rwo->start = rwo->end = 0;
+                    rwo->op.version = 0;
                     rwo_read(rwo);
                     delete subop;
                     return;
                 }
-                rwo->error_code = -subop->retval;
+                rwo->error_code = subop->retval;
                 rwo->error_offset = subop->offset;
                 rwo->error_read = false;
             }
@@ -633,7 +640,7 @@ struct snap_merger_t
             {
                 char buf[1024];
                 snprintf(buf, 1024, "Error %s target at offset %jx: %s",
-                    rwo->error_read ? "reading" : "writing", rwo->error_offset, strerror(rwo->error_code));
+                    rwo->error_read ? "reading" : "writing", rwo->error_offset, strerror(-rwo->error_code));
                 rwo_error = std::string(buf);
             }
             delete rwo;