Refactored a bit, added comments on the file systems.

LightlessSync/FileCache/FileCompactor.cs

@@ -1,5 +1,6 @@
 using LightlessSync.LightlessConfiguration;
 using LightlessSync.Services;
+using LightlessSync.Utils;
 using Microsoft.Extensions.Logging;
 using System.Collections.Concurrent;
 using System.Diagnostics;
@@ -181,7 +182,7 @@ public sealed class FileCompactor : IDisposable
             if (result != 0)
                 return -1;
 
-            //return fragment size of linux
+            //return fragment size of Linux file system
             return (int)buf.f_frsize;
         }
         catch
@@ -413,12 +414,7 @@ public sealed class FileCompactor : IDisposable
 
             if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && !_dalamudUtilService.IsWine)
             {
-                int result = GetDiskFreeSpaceW(
+                int result = GetDiskFreeSpaceW(root, out uint sectorsPerCluster, out uint bytesPerSector, out _, out _);
-                    root,
-                    out uint sectorsPerCluster,
-                    out uint bytesPerSector,
-                    out _,
-                    out _);
 
                 if (result == 0)
                 {
@@ -495,12 +491,10 @@ public sealed class FileCompactor : IDisposable
             string output = proc.StandardOutput.ReadToEnd();
             proc.WaitForExit();
 
-            if (output.Contains("flags: compressed", StringComparison.OrdinalIgnoreCase))
+            bool compressed = output.Contains("flags: compressed", StringComparison.OrdinalIgnoreCase);
-            {
-                return true;
-            }
 
-            return false;
+            _logger.LogTrace("Btrfs compression check for {file}: {compressed}", path, compressed);
+            return compressed;
         }
         catch (Exception ex)
         {
@@ -586,41 +580,6 @@ public sealed class FileCompactor : IDisposable
         }
     }
 
-    private string GetMountOptionsForPath(string path)
-    {
-        try
-        {
-            var fullPath = Path.GetFullPath(path);
-            var mounts = File.ReadAllLines("/proc/mounts");
-            string bestMount = string.Empty;
-            string mountOptions = string.Empty;
-
-            foreach (var line in mounts)
-            {
-                var parts = line.Split(' ');
-                if (parts.Length < 4) continue;
-                var mountPoint = parts[1].Replace("\\040", " ", StringComparison.Ordinal);
-                string normalized;
-                try { normalized = Path.GetFullPath(mountPoint); }
-                catch { normalized = mountPoint; }
-
-                if (fullPath.StartsWith(normalized, StringComparison.Ordinal) &&
-                    normalized.Length > bestMount.Length)
-                {
-                    bestMount = normalized;
-                    mountOptions = parts[3];
-                }
-            }
-
-            return mountOptions;
-        }
-        catch (Exception ex)
-        {
-            _logger.LogDebug(ex, "Failed to get mount options for {path}", path);
-            return string.Empty;
-        }
-    }
-
     private struct WOF_FILE_COMPRESSION_INFO_V1
     {
         public CompressionAlgorithm Algorithm;

LightlessSync/Utils/FileSystemHelper.cs

@@ -8,15 +8,15 @@ namespace LightlessSync.Utils
         public enum FilesystemType
         {
             Unknown = 0,
-            NTFS, // Compressable
+            NTFS, // Compressable on file level
-            Btrfs, // Compressable
+            Btrfs, // Compressable on file level
-            Ext4,
+            Ext4, // Uncompressable
-            Xfs,
+            Xfs, // Uncompressable
-            Apfs,
+            Apfs, // Compressable on OS
-            HfsPlus,
+            HfsPlus, // Compressable on OS
-            Fat,
+            Fat, // Uncompressable
-            Exfat,
+            Exfat, // Uncompressable
-            Zfs // Compressable
+            Zfs // Compressable, not on file level
         }
 
         private const string _mountPath = "/proc/mounts";
@@ -105,6 +105,40 @@ namespace LightlessSync.Utils
             }
         }
 
+        public static string GetMountOptionsForPath(string path)
+        {
+            try
+            {
+                var fullPath = Path.GetFullPath(path);
+                var mounts = File.ReadAllLines("/proc/mounts");
+                string bestMount = string.Empty;
+                string mountOptions = string.Empty;
+
+                foreach (var line in mounts)
+                {
+                    var parts = line.Split(' ');
+                    if (parts.Length < 4) continue;
+                    var mountPoint = parts[1].Replace("\\040", " ", StringComparison.Ordinal);
+                    string normalized;
+                    try { normalized = Path.GetFullPath(mountPoint); }
+                    catch { normalized = mountPoint; }
+
+                    if (fullPath.StartsWith(normalized, StringComparison.Ordinal) &&
+                        normalized.Length > bestMount.Length)
+                    {
+                        bestMount = normalized;
+                        mountOptions = parts[3];
+                    }
+                }
+
+                return mountOptions;
+            }
+            catch (Exception ex)
+            {
+                return string.Empty;
+            }
+        }
+
         private static FilesystemType GetLinuxFilesystemType(string filePath)
         {
             try