readSEGYSTACK recreates volD with optimal chunking

include/h5geo/h5vol.h

@@ -136,7 +136,7 @@ class H5Vol : public H5BaseObject
   virtual bool recreateVolD(
       size_t nX, size_t nY, size_t nZ,
       size_t xChunk, size_t yChunk, size_t zChunk,
-      size_t compressionLevel) = 0;
+      unsigned compressionLevel) = 0;
 };
 
 using H5Vol_ptr = std::unique_ptr<H5Vol, h5geo::ObjectDeleter>;

include/h5geo/private/h5volimpl.h

@@ -92,7 +92,7 @@ class H5VolImpl : public H5BaseObjectImpl<H5Vol>
   virtual bool recreateVolD(
       size_t nX, size_t nY, size_t nZ,
       size_t xChunk, size_t yChunk, size_t zChunk,
-      size_t compressionLevel) override;
+      unsigned compressionLevel) override;
 
   //----------- FRIEND CLASSES -----------
   friend class H5VolContainerImpl;

src/h5geo/h5core_segy.cpp

@@ -1143,13 +1143,24 @@ bool readSEGYSTACK(
     return false;
 
   size_t nil = dv.quot;
-  if (!vol->resize(nxl, nil, nSamp))
+
+  // Recreate volume dataset with optimal chunking.
+  // Without this 2D volume may work extremely slow.
+  H5VolParam vp = vol->getParam();
+  vp.nX = nxl;
+  vp.nY = nil;
+  vp.nZ = nSamp;
+  vp.xChunkSize = std::min(vp.xChunkSize, nxl);
+  vp.yChunkSize = std::min(vp.yChunkSize, nil);
+  vp.zChunkSize = std::min(vp.zChunkSize, nSamp);
+  if (!vol->recreateVolD(vp.nX, vp.nY, vp.nZ, 
+      vp.xChunkSize, vp.yChunkSize, vp.zChunkSize,
+      vp.compression_level))
     return false;
 
   // N - number of slices written at once (usually 
   // should be equal to Y-chunkSize to acieve best IO speed)
   size_t N = 64;
-  H5VolParam vp = vol->getParam();
   if (vp.yChunkSize > 0 &&
       vp.nY > 0 &&
       vp.yChunkSize < vp.nY){

src/h5geo/h5volimpl.cpp

@@ -557,7 +557,7 @@ bool H5VolImpl::exportToSEGY(
 bool H5VolImpl::recreateVolD(
     size_t nX, size_t nY, size_t nZ,
     size_t xChunk, size_t yChunk, size_t zChunk,
-    size_t compressionLevel)
+    unsigned compressionLevel)
 {
   if (nX < 1 || nY < 1 || nZ < 1)
     return false;