New: Fast copy using reflink on btrfs volumes

Signed-off-by: Robin Dadswell <robin@dadswell.email>

src/NzbDrone.Common/Disk/DiskProviderBase.cs

@@ -212,6 +212,24 @@ public void DeleteFile(string path)
             _fileSystem.File.Delete(path);
         }
 
+        public void CloneFile(string source, string destination, bool overwrite = false)
+        {
+            Ensure.That(source, () => source).IsValidPath();
+            Ensure.That(destination, () => destination).IsValidPath();
+
+            if (source.PathEquals(destination))
+            {
+                throw new IOException(string.Format("Source and destination can't be the same {0}", source));
+            }
+
+            CloneFileInternal(source, destination, overwrite);
+        }
+
+        protected virtual void CloneFileInternal(string source, string destination, bool overwrite = false)
+        {
+            CopyFileInternal(source, destination, overwrite);
+        }
+
         public void CopyFile(string source, string destination, bool overwrite = false)
         {
             Ensure.That(source, () => source).IsValidPath();
@@ -262,8 +280,18 @@ protected virtual void MoveFileInternal(string source, string destination)
             _fileSystem.File.Move(source, destination);
         }
 
+        public virtual bool TryRenameFile(string source, string destination)
+        {
+            return false;
+        }
+
         public abstract bool TryCreateHardLink(string source, string destination);
 
+        public virtual bool TryCreateRefLink(string source, string destination)
+        {
+            return false;
+        }
+
         public void DeleteFolder(string path, bool recursive)
         {
             Ensure.That(path, () => path).IsValidPath();

src/NzbDrone.Common/Disk/DiskTransferService.cs

@@ -284,18 +284,45 @@ public TransferMode TransferFile(string sourcePath, string targetPath, TransferM
             var targetDriveFormat = targetMount?.DriveFormat ?? string.Empty;
 
             var isCifs = targetDriveFormat == "cifs";
+            var isBtrfs = sourceDriveFormat == "btrfs" && targetDriveFormat == "btrfs";
 
             if (mode.HasFlag(TransferMode.Copy))
             {
+                if (isBtrfs)
+                {
+                    if (_diskProvider.TryCreateRefLink(sourcePath, targetPath))
+                    {
+                        return TransferMode.Copy;
+                    }
+                }
+
                 TryCopyFileVerified(sourcePath, targetPath, originalSize);
                 return TransferMode.Copy;
             }
 
             if (mode.HasFlag(TransferMode.Move))
             {
+                if (isBtrfs)
+                {
+                    if (isSameMount && _diskProvider.TryRenameFile(sourcePath, targetPath))
+                    {
+                        _logger.Trace("Renamed [{0}] to [{1}].", sourcePath, targetPath);
+                        return TransferMode.Move;
+                    }
+
+                    if (_diskProvider.TryCreateRefLink(sourcePath, targetPath))
+                    {
+                        _logger.Trace("Reflink successful, deleting source [{0}].", sourcePath);
+                        _diskProvider.DeleteFile(sourcePath);
+                        return TransferMode.Move;
+                    }
+                }
+
                 if (isCifs && !isSameMount)
                 {
+                    _logger.Trace("On cifs mount. Starting verified copy [{0}] to [{1}].", sourcePath, targetPath);
                     TryCopyFileVerified(sourcePath, targetPath, originalSize);
+                    _logger.Trace("Copy successful, deleting source [{0}].", sourcePath);
                     _diskProvider.DeleteFile(sourcePath);
                     return TransferMode.Move;
                 }

src/NzbDrone.Common/Disk/IDiskProvider.cs

@@ -30,10 +30,13 @@ public interface IDiskProvider
         long GetFileSize(string path);
         void CreateFolder(string path);
         void DeleteFile(string path);
+        void CloneFile(string source, string destination, bool overwrite = false);
         void CopyFile(string source, string destination, bool overwrite = false);
         void MoveFile(string source, string destination, bool overwrite = false);
         void MoveFolder(string source, string destination);
+        bool TryRenameFile(string source, string destination);
         bool TryCreateHardLink(string source, string destination);
+        bool TryCreateRefLink(string source, string destination);
         void DeleteFolder(string path, bool recursive);
         string ReadAllText(string filePath);
         void WriteAllText(string filename, string contents);

src/NzbDrone.Mono/Disk/DiskProvider.cs

@@ -23,20 +23,27 @@ public class DiskProvider : DiskProviderBase
 
         private readonly IProcMountProvider _procMountProvider;
         private readonly ISymbolicLinkResolver _symLinkResolver;
+        private readonly IRefLinkCreator _createRefLink;
 
         public DiskProvider(IProcMountProvider procMountProvider,
-                            ISymbolicLinkResolver symLinkResolver)
-        : this(new FileSystem(), procMountProvider, symLinkResolver)
+                            ISymbolicLinkResolver symLinkResolver,
+                            IRefLinkCreator createRefLink,
+                            Logger logger)
+        : this(new FileSystem(), procMountProvider, symLinkResolver, createRefLink, logger)
         {
         }
 
         public DiskProvider(IFileSystem fileSystem,
                             IProcMountProvider procMountProvider,
-                            ISymbolicLinkResolver symLinkResolver)
+                            ISymbolicLinkResolver symLinkResolver,
+                            IRefLinkCreator createRefLink,
+                            Logger logger)
         : base(fileSystem)
         {
             _procMountProvider = procMountProvider;
             _symLinkResolver = symLinkResolver;
+            _createRefLink = createRefLink;
+            _logger = logger;
         }
 
         public override IMount GetMount(string path)
@@ -77,7 +84,7 @@ public override void SetPermissions(string path, string mask)
 
             var permissions = NativeConvert.FromOctalPermissionString(mask);
 
-            if (Directory.Exists(path))
+            if (_fileSystem.Directory.Exists(path))
             {
                 permissions = GetFolderPermissions(permissions);
             }
@@ -184,6 +191,19 @@ protected override bool IsSpecialMount(IMount mount)
             return mount?.TotalSize;
         }
 
+        protected override void CloneFileInternal(string source, string destination, bool overwrite)
+        {
+            if (!FileExists(destination) && !UnixFileSystemInfo.GetFileSystemEntry(source).IsSymbolicLink)
+            {
+                if (_createRefLink.TryCreateRefLink(source, destination))
+                {
+                    return;
+                }
+            }
+
+            CopyFileInternal(source, destination, overwrite);
+        }
+
         protected override void CopyFileInternal(string source, string destination, bool overwrite)
         {
             var sourceInfo = UnixFileSystemInfo.GetFileSystemEntry(source);
@@ -259,6 +279,137 @@ protected override void MoveFileInternal(string source, string destination)
             }
         }
 
+        private void TransferFilePatched(string source, string destination, bool overwrite, bool move)
+        {
+            // Mono 6.x throws errors if permissions or timestamps cannot be set
+            // - In 6.0 it'll leave a full length file
+            // - In 6.6 it'll leave a zero length file
+            // Catch the exception and attempt to handle these edgecases
+
+            // Mono 6.x till 6.10 doesn't properly try use rename first.
+            if (move &&
+                ((PlatformInfo.Platform == PlatformType.Mono && PlatformInfo.GetVersion() < new Version(6, 10)) ||
+                 (PlatformInfo.Platform == PlatformType.NetCore)))
+            {
+                if (Syscall.lstat(source, out var sourcestat) == 0 &&
+                    Syscall.lstat(destination, out var deststat) != 0 &&
+                    Syscall.rename(source, destination) == 0)
+                {
+                    _logger.Trace("Moved '{0}' -> '{1}' using Syscall.rename", source, destination);
+                    return;
+                }
+            }
+
+            try
+            {
+                if (move)
+                {
+                    base.MoveFileInternal(source, destination);
+                }
+                else
+                {
+                    base.CopyFileInternal(source, destination);
+                }
+            }
+            catch (UnauthorizedAccessException)
+            {
+                var srcInfo = new FileInfo(source);
+                var dstInfo = new FileInfo(destination);
+                var exists = dstInfo.Exists && srcInfo.Exists;
+
+                if (PlatformInfo.Platform == PlatformType.Mono && PlatformInfo.GetVersion() >= new Version(6, 6) &&
+                    exists && dstInfo.Length == 0 && srcInfo.Length != 0)
+                {
+                    // mono >=6.6 bug: zero length file since chmod happens at the start
+                    _logger.Debug("{3} failed to {2} file likely due to known {3} bug, attempting to {2} directly. '{0}' -> '{1}'", source, destination, move ? "move" : "copy", PlatformInfo.PlatformName);
+
+                    try
+                    {
+                        _logger.Trace("Copying content from {0} to {1} ({2} bytes)", source, destination, srcInfo.Length);
+                        using (var srcStream = new FileStream(source, FileMode.Open, FileAccess.Read))
+                        using (var dstStream = new FileStream(destination, FileMode.Create, FileAccess.Write))
+                        {
+                            srcStream.CopyTo(dstStream);
+                        }
+                    }
+                    catch
+                    {
+                        // If it fails again then bail
+                        throw;
+                    }
+                }
+                else if (((PlatformInfo.Platform == PlatformType.Mono &&
+                           PlatformInfo.GetVersion() >= new Version(6, 0) &&
+                           PlatformInfo.GetVersion() < new Version(6, 6)) ||
+                          PlatformInfo.Platform == PlatformType.NetCore) &&
+                         exists && dstInfo.Length == srcInfo.Length)
+                {
+                    // mono 6.0, mono 6.4 and netcore 3.1 bug: full length file since utime and chmod happens at the end
+                    _logger.Debug("{3} failed to {2} file likely due to known {3} bug, attempting to {2} directly. '{0}' -> '{1}'", source, destination, move ? "move" : "copy", PlatformInfo.PlatformName);
+
+                    // Check at least part of the file since UnauthorizedAccess can happen due to legitimate reasons too
+                    var checkLength = (int)Math.Min(64 * 1024, dstInfo.Length);
+                    if (checkLength > 0)
+                    {
+                        var srcData = new byte[checkLength];
+                        var dstData = new byte[checkLength];
+
+                        _logger.Trace("Check last {0} bytes from {1}", checkLength, destination);
+
+                        using (var srcStream = new FileStream(source, FileMode.Open, FileAccess.Read))
+                        using (var dstStream = new FileStream(destination, FileMode.Open, FileAccess.Read))
+                        {
+                            srcStream.Position = srcInfo.Length - checkLength;
+                            dstStream.Position = dstInfo.Length - checkLength;
+
+                            srcStream.Read(srcData, 0, checkLength);
+                            dstStream.Read(dstData, 0, checkLength);
+                        }
+
+                        for (var i = 0; i < checkLength; i++)
+                        {
+                            if (srcData[i] != dstData[i])
+                            {
+                                // Files aren't the same, the UnauthorizedAccess was unrelated
+                                _logger.Trace("Copy was incomplete, rethrowing original error");
+                                throw;
+                            }
+                        }
+
+                        _logger.Trace("Copy was complete, finishing {0} operation", move ? "move" : "copy");
+                    }
+                }
+                else
+                {
+                    // Unrecognized situation, the UnauthorizedAccess was unrelated
+                    throw;
+                }
+
+                if (exists)
+                {
+                    try
+                    {
+                        dstInfo.LastWriteTimeUtc = srcInfo.LastWriteTimeUtc;
+                    }
+                    catch
+                    {
+                        _logger.Debug("Unable to change last modified date for {0}, skipping.", destination);
+                    }
+
+                    if (move)
+                    {
+                        _logger.Trace("Removing source file {0}", source);
+                        File.Delete(source);
+                    }
+                }
+            }
+        }
+
+        public override bool TryRenameFile(string source, string destination)
+        {
+            return Syscall.rename(source, destination) == 0;
+        }
+
         public override bool TryCreateHardLink(string source, string destination)
         {
             try
@@ -280,6 +431,11 @@ public override bool TryCreateHardLink(string source, string destination)
             }
         }
 
+        public override bool TryCreateRefLink(string source, string destination)
+        {
+            return _createRefLink.TryCreateRefLink(source, destination);
+        }
+
         private uint GetUserId(string user)
         {
             if (user.IsNullOrWhiteSpace())

src/NzbDrone.Mono/Disk/RefLinkCreator.cs

@@ -0,0 +1,75 @@
+using System;
+using Mono.Unix;
+using Mono.Unix.Native;
+using NLog;
+using NzbDrone.Common.EnvironmentInfo;
+using NzbDrone.Mono.Interop;
+
+namespace NzbDrone.Mono.Disk
+{
+    public interface IRefLinkCreator
+    {
+        bool TryCreateRefLink(string srcPath, string linkPath);
+    }
+
+    public class RefLinkCreator : IRefLinkCreator
+    {
+        private readonly Logger _logger;
+        private readonly bool _supported;
+
+        public RefLinkCreator(Logger logger)
+        {
+            _logger = logger;
+
+            // Only support x86_64 because we know the FICLONE value is valid for it
+            _supported = OsInfo.IsLinux && (Syscall.uname(out var results) == 0 && results.machine == "x86_64");
+        }
+
+        public bool TryCreateRefLink(string srcPath, string linkPath)
+        {
+            if (!_supported)
+            {
+                return false;
+            }
+
+            try
+            {
+                using (var srcHandle = NativeMethods.open(srcPath, OpenFlags.O_RDONLY))
+                {
+                    if (srcHandle.IsInvalid)
+                    {
+                        _logger.Trace("Failed to create reflink at '{0}' to '{1}': Couldn't open source file", linkPath, srcPath);
+                        return false;
+                    }
+
+                    using (var linkHandle = NativeMethods.open(linkPath, OpenFlags.O_WRONLY | OpenFlags.O_CREAT | OpenFlags.O_TRUNC))
+                    {
+                        if (linkHandle.IsInvalid)
+                        {
+                            _logger.Trace("Failed to create reflink at '{0}' to '{1}': Couldn't create new link file", linkPath, srcPath);
+                            return false;
+                        }
+
+                        if (NativeMethods.clone_file(linkHandle, srcHandle) == -1)
+                        {
+                            var error = new UnixIOException();
+                            linkHandle.Dispose();
+                            Syscall.unlink(linkPath);
+                            _logger.Trace("Failed to create reflink at '{0}' to '{1}': {2}", linkPath, srcPath, error.Message);
+                            return false;
+                        }
+
+                        _logger.Trace("Created reflink at '{0}' to '{1}'", linkPath, srcPath);
+                        return true;
+                    }
+                }
+            }
+            catch (Exception ex)
+            {
+                Syscall.unlink(linkPath);
+                _logger.Trace(ex, "Failed to create reflink at '{0}' to '{1}'", linkPath, srcPath);
+                return false;
+            }
+        }
+    }
+}

src/NzbDrone.Mono/Interop/NativeMethods.cs

@@ -0,0 +1,28 @@
+using System.Runtime.InteropServices;
+using Mono.Unix.Native;
+
+namespace NzbDrone.Mono.Interop
+{
+    internal enum IoctlRequest : uint
+    {
+        // Hardcoded ioctl for FICLONE on a typical linux system
+        // #define FICLONE _IOW(0x94, 9, int)
+        FICLONE = 0x40049409
+    }
+
+    internal static class NativeMethods
+    {
+        [DllImport("libc", EntryPoint = "ioctl", SetLastError = true)]
+        private static extern int Ioctl(SafeUnixHandle dst_fd, IoctlRequest request, SafeUnixHandle src_fd);
+
+        public static SafeUnixHandle open(string pathname, OpenFlags flags)
+        {
+            return new SafeUnixHandle(Syscall.open(pathname, flags));
+        }
+
+        internal static int clone_file(SafeUnixHandle link_fd, SafeUnixHandle src_fd)
+        {
+            return Ioctl(link_fd, IoctlRequest.FICLONE, src_fd);
+        }
+    }
+}

src/NzbDrone.Mono/Interop/SafeUnixHandle.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Runtime.ConstrainedExecution;
+using System.Runtime.InteropServices;
+using System.Security.Permissions;
+using Mono.Unix.Native;
+
+namespace NzbDrone.Mono.Interop
+{
+    [SecurityPermission(SecurityAction.InheritanceDemand, UnmanagedCode = true)]
+    [SecurityPermission(SecurityAction.Demand, UnmanagedCode = true)]
+    internal sealed class SafeUnixHandle : SafeHandle
+    {
+        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
+        private SafeUnixHandle()
+            : base(new IntPtr(-1), true)
+        {
+        }
+
+        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
+        public SafeUnixHandle(int fd)
+            : base(new IntPtr(-1), true)
+        {
+            handle = new IntPtr(fd);
+        }
+
+        public override bool IsInvalid
+        {
+            get { return handle == new IntPtr(-1); }
+        }
+
+        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)]
+        protected override bool ReleaseHandle()
+        {
+            return Syscall.close(handle.ToInt32()) != -1;
+        }
+    }
+}