requested changes from paulirwin at PR#1429

Author: marionoack

src/Lucene.Net/Store/FSDirectory.cs

@@ -317,33 +317,33 @@ public override void DeleteFile(string name)
             EnsureOpen();
             string file = Path.Combine(m_directory.FullName, name);
 
-                // LUCENENET specific: We need to explicitly throw when the file has already been deleted,
-                // since FileInfo doesn't do that for us.
-                // (An enhancement carried over from Lucene 8.2.0)
-                if (!File.Exists(file))
-                {
-                    throw new FileNotFoundException("Cannot delete " + file + " because it doesn't exist.");
-                }
+            // LUCENENET specific: We need to explicitly throw when the file has already been deleted,
+            // since FileInfo doesn't do that for us.
+            // (An enhancement carried over from Lucene 8.2.0)
+            if (!File.Exists(file))
+            {
+                throw new FileNotFoundException("Cannot delete " + file + " because it doesn't exist.");
+            }
 
-            // LUCENENET specific: Do NOT hold m_syncLock while deleting. On a network share (SMB),
+            // LUCENENET NOTE: Do NOT hold m_syncLock while deleting. On a network share (SMB),
             // File.Delete can block for a long time (e.g. waiting for the server to break an
             // oplock/lease on a file this client still has open). Holding m_syncLock here would
             // block every concurrent Sync() and IndexOutput.Dispose() on this directory behind
             // a single stalled delete, freezing the whole writer. Only the m_staleFiles
             // bookkeeping below needs the lock (see remarks for the m_staleFiles field);
             // upstream Java likewise performs the delete without any directory-wide lock.
-                try
-                {
-                    File.Delete(file);
-                    if (File.Exists(file))
-                    {
-                        throw new IOException("Cannot delete " + file);
-                    }
-                }
-                catch (Exception e)
+            try
+            {
+                File.Delete(file);
+                if (File.Exists(file))
                 {
-                    throw new IOException("Cannot delete " + file, e);
+                    throw new IOException("Cannot delete " + file);
                 }
+            }
+            catch (Exception e)
+            {
+                throw new IOException("Cannot delete " + file, e);
+            }
 
             UninterruptableMonitor.Enter(m_syncLock);
             try

src/Lucene.Net/Store/MMapDirectory.cs

@@ -194,13 +194,7 @@ public override IndexInput OpenInput(string name, IOContext context)
             EnsureOpen();
             EnsureCanRead(name); // LUCENENET-specific: backported call site from Lucene 6.0.0
             var file = Path.Combine(Directory.FullName, name); // LUCENENET specific: changed to use string file name instead of allocating a FileInfo (#832)
-            // LUCENENET specific: Add FileShare.Delete (a deliberate divergence from upstream Java's RandomAccessFile,
-            // which omits it) to match SimpleFSDirectory, NIOFSDirectory and our other handles, giving Windows the same
-            // delete-while-open semantics POSIX already provides so index files can be deleted while a read handle is
-            // open (#1283). Without it, a pending delete of a still-mapped file on an SMB share can block inside
-            // File.Delete while the server waits for this client's lease break, which cannot complete while mapped
-            // views are active.
-            var fc = new FileStream(file, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete);
+            var fc = new FileStream(file, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
             return new MMapIndexInput(this, "MMapIndexInput(path=\"" + file + "\")", fc);
         }