From 03714dfd5fbfd976f090a6edae6c80d20ad034c9 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Fri, 10 Jun 2022 10:04:18 +0700
Subject: [PATCH 01/19] do t.storage.Flush() when torrent completion happen.
 And when storage.Close() happening.

---
 mmap_span/mmap_span.go    | 21 ++++++++++++++++++++-
 storage/bolt.go           |  2 ++
 storage/file.go           |  5 +++++
 storage/interface.go      |  1 +
 storage/mmap.go           |  9 ++++++++-
 storage/piece-resource.go |  6 +++++-
 torrent.go                |  4 ++++
 7 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/mmap_span/mmap_span.go b/mmap_span/mmap_span.go
index 6a6c8392ed..ebd3f0ac3e 100644
--- a/mmap_span/mmap_span.go
+++ b/mmap_span/mmap_span.go
@@ -19,11 +19,30 @@ func (ms *MMapSpan) Append(mMap mmap.MMap) {
 	ms.mMaps = append(ms.mMaps, mMap)
 }
 
+func (ms *MMapSpan) Flush() (errs []error) {
+	ms.mu.Lock()
+	defer ms.mu.Unlock()
+	for _, mMap := range ms.mMaps {
+		err := mMap.Flush()
+		if err != nil {
+			errs = append(errs, err)
+		}
+	}
+	// This is for issue 211.
+	ms.mMaps = nil
+	ms.InitIndex()
+	return
+}
+
 func (ms *MMapSpan) Close() (errs []error) {
 	ms.mu.Lock()
 	defer ms.mu.Unlock()
 	for _, mMap := range ms.mMaps {
-		err := mMap.Unmap()
+		err := mMap.Flush()
+		if err != nil {
+			errs = append(errs, err)
+		}
+		err = mMap.Unmap()
 		if err != nil {
 			errs = append(errs, err)
 		}
diff --git a/storage/bolt.go b/storage/bolt.go
index 945b24995d..5aad4558b2 100644
--- a/storage/bolt.go
+++ b/storage/bolt.go
@@ -47,6 +47,7 @@ func (me *boltClient) OpenTorrent(_ *metainfo.Info, infoHash metainfo.Hash) (Tor
 	return TorrentImpl{
 		Piece: t.Piece,
 		Close: t.Close,
+		Flush: t.Flush,
 	}, nil
 }
 
@@ -62,3 +63,4 @@ func (me *boltTorrent) Piece(p metainfo.Piece) PieceImpl {
 }
 
 func (boltTorrent) Close() error { return nil }
+func (boltTorrent) Flush() error { return nil }
diff --git a/storage/file.go b/storage/file.go
index d07dc7e915..ad339ed238 100644
--- a/storage/file.go
+++ b/storage/file.go
@@ -90,6 +90,7 @@ func (fs fileClientImpl) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash
 	return TorrentImpl{
 		Piece: t.Piece,
 		Close: t.Close,
+		Flush: t.Flush,
 	}, nil
 }
 
@@ -122,6 +123,10 @@ func (fs *fileTorrentImpl) Close() error {
 	return nil
 }
 
+func (fs *fileTorrentImpl) Flush() error {
+	return nil
+}
+
 // A helper to create zero-length files which won't appear for file-orientated storage since no
 // writes will ever occur to them (no torrent data is associated with a zero-length file). The
 // caller should make sure the file name provided is safe/sanitized.
diff --git a/storage/interface.go b/storage/interface.go
index ee6e6336cd..3d1bfb3bfe 100644
--- a/storage/interface.go
+++ b/storage/interface.go
@@ -22,6 +22,7 @@ type TorrentCapacity *func() (cap int64, capped bool)
 type TorrentImpl struct {
 	Piece func(p metainfo.Piece) PieceImpl
 	Close func() error
+	Flush func() error
 	// Storages that share the same space, will provide equal pointers. The function is called once
 	// to determine the storage for torrents sharing the same function pointer, and mutated in
 	// place.
diff --git a/storage/mmap.go b/storage/mmap.go
index 300d863510..a9d922ac20 100644
--- a/storage/mmap.go
+++ b/storage/mmap.go
@@ -41,7 +41,7 @@ func (s *mmapClientImpl) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash
 		span:     span,
 		pc:       s.pc,
 	}
-	return TorrentImpl{Piece: t.Piece, Close: t.Close}, err
+	return TorrentImpl{Piece: t.Piece, Close: t.Close, Flush: t.Flush}, err
 }
 
 func (s *mmapClientImpl) Close() error {
@@ -71,6 +71,13 @@ func (ts *mmapTorrentStorage) Close() error {
 	}
 	return nil
 }
+func (ts *mmapTorrentStorage) Flush() error {
+	errs := ts.span.Flush()
+	if len(errs) > 0 {
+		return errs[0]
+	}
+	return nil
+}
 
 type mmapStoragePiece struct {
 	pc PieceCompletionGetSetter
diff --git a/storage/piece-resource.go b/storage/piece-resource.go
index ec3848df21..1d75b0e789 100644
--- a/storage/piece-resource.go
+++ b/storage/piece-resource.go
@@ -49,12 +49,16 @@ func (piecePerResourceTorrentImpl) Close() error {
 	return nil
 }
 
+func (piecePerResourceTorrentImpl) Flush() error {
+	return nil
+}
+
 func (s piecePerResource) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash) (TorrentImpl, error) {
 	t := piecePerResourceTorrentImpl{
 		s,
 		make([]sync.RWMutex, info.NumPieces()),
 	}
-	return TorrentImpl{Piece: t.Piece, Close: t.Close}, nil
+	return TorrentImpl{Piece: t.Piece, Close: t.Close, Flush: t.Flush}, nil
 }
 
 func (s piecePerResourceTorrentImpl) Piece(p metainfo.Piece) PieceImpl {
diff --git a/torrent.go b/torrent.go
index c8606ad82c..10d89a1a63 100644
--- a/torrent.go
+++ b/torrent.go
@@ -2461,7 +2461,11 @@ func (t *Torrent) pieceRequestIndexOffset(piece pieceIndex) RequestIndex {
 }
 
 func (t *Torrent) updateComplete() {
+	before := t.Complete.Bool()
 	t.Complete.SetBool(t.haveAllPieces())
+	if !before && t.Complete.Bool() {
+		_ = t.storage.Flush()
+	}
 }
 
 func (t *Torrent) cancelRequest(r RequestIndex) *Peer {

From 82f028f41fcf55e912a523a8fe0c24509bd64bf9 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Fri, 10 Jun 2022 10:57:40 +0700
Subject: [PATCH 02/19] do t.storage.Flush() when torrent completion happen.
 And when storage.Close() happening.

---
 bad_storage.go               | 1 +
 peerconn_test.go             | 2 +-
 storage/disabled/disabled.go | 3 +++
 storage/sqlite/direct.go     | 5 ++++-
 test/issue377_test.go        | 6 +++++-
 5 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/bad_storage.go b/bad_storage.go
index fc15beb907..268ed725f3 100644
--- a/bad_storage.go
+++ b/bad_storage.go
@@ -17,6 +17,7 @@ var _ storage.ClientImpl = badStorage{}
 func (bs badStorage) OpenTorrent(*metainfo.Info, metainfo.Hash) (storage.TorrentImpl, error) {
 	return storage.TorrentImpl{
 		Piece: bs.Piece,
+		Flush: func() error { return nil },
 	}, nil
 }
 
diff --git a/peerconn_test.go b/peerconn_test.go
index 1bd9712b86..b1533d70ab 100644
--- a/peerconn_test.go
+++ b/peerconn_test.go
@@ -102,7 +102,7 @@ func BenchmarkConnectionMainReadLoop(b *testing.B) {
 		Length:      1 << 20,
 		PieceLength: 1 << 20,
 	}))
-	t.storage = &storage.Torrent{TorrentImpl: storage.TorrentImpl{Piece: ts.Piece, Close: ts.Close}}
+	t.storage = &storage.Torrent{TorrentImpl: storage.TorrentImpl{Piece: ts.Piece, Close: ts.Close, Flush: func() error { return nil }}}
 	t.onSetInfo()
 	t._pendingPieces.Add(0)
 	r, w := net.Pipe()
diff --git a/storage/disabled/disabled.go b/storage/disabled/disabled.go
index f511222ae2..936e6feae9 100644
--- a/storage/disabled/disabled.go
+++ b/storage/disabled/disabled.go
@@ -20,6 +20,9 @@ func (c Client) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash) (storag
 		Close: func() error {
 			return nil
 		},
+		Flush: func() error {
+			return nil
+		},
 		Capacity: &capFunc,
 	}, nil
 }
diff --git a/storage/sqlite/direct.go b/storage/sqlite/direct.go
index 3d51fd316b..3bcb782d07 100644
--- a/storage/sqlite/direct.go
+++ b/storage/sqlite/direct.go
@@ -40,7 +40,7 @@ type client struct {
 
 func (c *client) OpenTorrent(*metainfo.Info, metainfo.Hash) (storage.TorrentImpl, error) {
 	t := torrent{c.Cache}
-	return storage.TorrentImpl{Piece: t.Piece, Close: t.Close, Capacity: &c.capacity}, nil
+	return storage.TorrentImpl{Piece: t.Piece, Close: t.Close, Capacity: &c.capacity, Flush: t.Flush}, nil
 }
 
 type torrent struct {
@@ -59,6 +59,9 @@ func (t torrent) Piece(p metainfo.Piece) storage.PieceImpl {
 func (t torrent) Close() error {
 	return nil
 }
+func (t torrent) Flush() error {
+	return nil
+}
 
 type piece struct {
 	sb squirrel.Blob
diff --git a/test/issue377_test.go b/test/issue377_test.go
index 48e5abfbf3..5087d067c4 100644
--- a/test/issue377_test.go
+++ b/test/issue377_test.go
@@ -126,8 +126,12 @@ func (me *diskFullStorage) Close() error {
 	return nil
 }
 
+func (me *diskFullStorage) Flush() error {
+	return nil
+}
+
 func (d *diskFullStorage) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash) (storage.TorrentImpl, error) {
-	return storage.TorrentImpl{Piece: d.Piece, Close: d.Close}, nil
+	return storage.TorrentImpl{Piece: d.Piece, Close: d.Close, Flush: d.Flush}, nil
 }
 
 type pieceImpl struct {

From 78741df1850dd8d355b5c1de687959163c553c4b Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Sat, 18 Jun 2022 09:02:35 +0600
Subject: [PATCH 03/19] check nil on caller

---
 bad_storage.go               | 1 -
 peerconn_test.go             | 2 +-
 storage/bolt.go              | 2 --
 storage/disabled/disabled.go | 3 ---
 storage/file.go              | 5 -----
 storage/piece-resource.go    | 6 +-----
 storage/sqlite/direct.go     | 5 +----
 test/issue377_test.go        | 6 +-----
 torrent.go                   | 2 +-
 9 files changed, 5 insertions(+), 27 deletions(-)

diff --git a/bad_storage.go b/bad_storage.go
index 268ed725f3..fc15beb907 100644
--- a/bad_storage.go
+++ b/bad_storage.go
@@ -17,7 +17,6 @@ var _ storage.ClientImpl = badStorage{}
 func (bs badStorage) OpenTorrent(*metainfo.Info, metainfo.Hash) (storage.TorrentImpl, error) {
 	return storage.TorrentImpl{
 		Piece: bs.Piece,
-		Flush: func() error { return nil },
 	}, nil
 }
 
diff --git a/peerconn_test.go b/peerconn_test.go
index b1533d70ab..1bd9712b86 100644
--- a/peerconn_test.go
+++ b/peerconn_test.go
@@ -102,7 +102,7 @@ func BenchmarkConnectionMainReadLoop(b *testing.B) {
 		Length:      1 << 20,
 		PieceLength: 1 << 20,
 	}))
-	t.storage = &storage.Torrent{TorrentImpl: storage.TorrentImpl{Piece: ts.Piece, Close: ts.Close, Flush: func() error { return nil }}}
+	t.storage = &storage.Torrent{TorrentImpl: storage.TorrentImpl{Piece: ts.Piece, Close: ts.Close}}
 	t.onSetInfo()
 	t._pendingPieces.Add(0)
 	r, w := net.Pipe()
diff --git a/storage/bolt.go b/storage/bolt.go
index 5aad4558b2..945b24995d 100644
--- a/storage/bolt.go
+++ b/storage/bolt.go
@@ -47,7 +47,6 @@ func (me *boltClient) OpenTorrent(_ *metainfo.Info, infoHash metainfo.Hash) (Tor
 	return TorrentImpl{
 		Piece: t.Piece,
 		Close: t.Close,
-		Flush: t.Flush,
 	}, nil
 }
 
@@ -63,4 +62,3 @@ func (me *boltTorrent) Piece(p metainfo.Piece) PieceImpl {
 }
 
 func (boltTorrent) Close() error { return nil }
-func (boltTorrent) Flush() error { return nil }
diff --git a/storage/disabled/disabled.go b/storage/disabled/disabled.go
index 936e6feae9..f511222ae2 100644
--- a/storage/disabled/disabled.go
+++ b/storage/disabled/disabled.go
@@ -20,9 +20,6 @@ func (c Client) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash) (storag
 		Close: func() error {
 			return nil
 		},
-		Flush: func() error {
-			return nil
-		},
 		Capacity: &capFunc,
 	}, nil
 }
diff --git a/storage/file.go b/storage/file.go
index ad339ed238..d07dc7e915 100644
--- a/storage/file.go
+++ b/storage/file.go
@@ -90,7 +90,6 @@ func (fs fileClientImpl) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash
 	return TorrentImpl{
 		Piece: t.Piece,
 		Close: t.Close,
-		Flush: t.Flush,
 	}, nil
 }
 
@@ -123,10 +122,6 @@ func (fs *fileTorrentImpl) Close() error {
 	return nil
 }
 
-func (fs *fileTorrentImpl) Flush() error {
-	return nil
-}
-
 // A helper to create zero-length files which won't appear for file-orientated storage since no
 // writes will ever occur to them (no torrent data is associated with a zero-length file). The
 // caller should make sure the file name provided is safe/sanitized.
diff --git a/storage/piece-resource.go b/storage/piece-resource.go
index 1d75b0e789..ec3848df21 100644
--- a/storage/piece-resource.go
+++ b/storage/piece-resource.go
@@ -49,16 +49,12 @@ func (piecePerResourceTorrentImpl) Close() error {
 	return nil
 }
 
-func (piecePerResourceTorrentImpl) Flush() error {
-	return nil
-}
-
 func (s piecePerResource) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash) (TorrentImpl, error) {
 	t := piecePerResourceTorrentImpl{
 		s,
 		make([]sync.RWMutex, info.NumPieces()),
 	}
-	return TorrentImpl{Piece: t.Piece, Close: t.Close, Flush: t.Flush}, nil
+	return TorrentImpl{Piece: t.Piece, Close: t.Close}, nil
 }
 
 func (s piecePerResourceTorrentImpl) Piece(p metainfo.Piece) PieceImpl {
diff --git a/storage/sqlite/direct.go b/storage/sqlite/direct.go
index 3bcb782d07..3d51fd316b 100644
--- a/storage/sqlite/direct.go
+++ b/storage/sqlite/direct.go
@@ -40,7 +40,7 @@ type client struct {
 
 func (c *client) OpenTorrent(*metainfo.Info, metainfo.Hash) (storage.TorrentImpl, error) {
 	t := torrent{c.Cache}
-	return storage.TorrentImpl{Piece: t.Piece, Close: t.Close, Capacity: &c.capacity, Flush: t.Flush}, nil
+	return storage.TorrentImpl{Piece: t.Piece, Close: t.Close, Capacity: &c.capacity}, nil
 }
 
 type torrent struct {
@@ -59,9 +59,6 @@ func (t torrent) Piece(p metainfo.Piece) storage.PieceImpl {
 func (t torrent) Close() error {
 	return nil
 }
-func (t torrent) Flush() error {
-	return nil
-}
 
 type piece struct {
 	sb squirrel.Blob
diff --git a/test/issue377_test.go b/test/issue377_test.go
index 5087d067c4..48e5abfbf3 100644
--- a/test/issue377_test.go
+++ b/test/issue377_test.go
@@ -126,12 +126,8 @@ func (me *diskFullStorage) Close() error {
 	return nil
 }
 
-func (me *diskFullStorage) Flush() error {
-	return nil
-}
-
 func (d *diskFullStorage) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash) (storage.TorrentImpl, error) {
-	return storage.TorrentImpl{Piece: d.Piece, Close: d.Close, Flush: d.Flush}, nil
+	return storage.TorrentImpl{Piece: d.Piece, Close: d.Close}, nil
 }
 
 type pieceImpl struct {
diff --git a/torrent.go b/torrent.go
index 10d89a1a63..104dad50ac 100644
--- a/torrent.go
+++ b/torrent.go
@@ -2463,7 +2463,7 @@ func (t *Torrent) pieceRequestIndexOffset(piece pieceIndex) RequestIndex {
 func (t *Torrent) updateComplete() {
 	before := t.Complete.Bool()
 	t.Complete.SetBool(t.haveAllPieces())
-	if !before && t.Complete.Bool() {
+	if !before && t.storage.Flush != nil && t.Complete.Bool() {
 		_ = t.storage.Flush()
 	}
 }

From b22e5c0678fe18debcb88d14d0fa4dd7c704e155 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Sat, 18 Jun 2022 09:09:52 +0600
Subject: [PATCH 04/19] clean

---
 mmap_span/mmap_span.go | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/mmap_span/mmap_span.go b/mmap_span/mmap_span.go
index ebd3f0ac3e..ee9eca6e10 100644
--- a/mmap_span/mmap_span.go
+++ b/mmap_span/mmap_span.go
@@ -28,9 +28,6 @@ func (ms *MMapSpan) Flush() (errs []error) {
 			errs = append(errs, err)
 		}
 	}
-	// This is for issue 211.
-	ms.mMaps = nil
-	ms.InitIndex()
 	return
 }
 

From 842f5612e96b06b9dbeb56400c147d873cf08a58 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Tue, 21 Jun 2022 08:26:19 +0600
Subject: [PATCH 05/19] FlushAsync method

---
 go.mod                 | 2 ++
 go.sum                 | 4 ++--
 mmap_span/mmap_span.go | 2 +-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/go.mod b/go.mod
index a23fd1ab36..080b8926b9 100644
--- a/go.mod
+++ b/go.mod
@@ -2,6 +2,8 @@ module github.com/anacrolix/torrent
 
 go 1.18
 
+replace github.com/edsrzf/mmap-go => github.com/AskAlexSharov/mmap-go v1.2.0
+
 require (
 	crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508
 	github.com/RoaringBitmap/roaring v1.0.1-0.20220510143707-3f418c4f42a4
diff --git a/go.sum b/go.sum
index 9b257b75a2..7ce14ab7c8 100644
--- a/go.sum
+++ b/go.sum
@@ -6,6 +6,8 @@ crawshaw.io/sqlite v0.3.2/go.mod h1:igAO5JulrQ1DbdZdtVq48mnZUBAPOeFzer7VhDWNtW4=
 crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508 h1:fILCBBFnjnrQ0whVJlGhfv1E/QiaFDNtGFBObEVRnYg=
 crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508/go.mod h1:igAO5JulrQ1DbdZdtVq48mnZUBAPOeFzer7VhDWNtW4=
 filippo.io/edwards25519 v1.0.0-rc.1 h1:m0VOOB23frXZvAOK44usCgLWvtsxIoMCTBGJZlpmGfU=
+github.com/AskAlexSharov/mmap-go v1.2.0 h1:5Tyz/L4+o3ywXN+50pq7DNAiu/YSwBPKeB2h1vJka80=
+github.com/AskAlexSharov/mmap-go v1.2.0/go.mod h1:19H/e8pUPLicwkyNgOykDXkJ9F0MHE+Z52B8EIth78Q=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/Julusian/godocdown v0.0.0-20170816220326-6d19f8ff2df8/go.mod h1:INZr5t32rG59/5xeltqoCJoNY7e5x/3xoY9WSWVWg74=
 github.com/RoaringBitmap/roaring v0.4.7/go.mod h1:8khRDP4HmeXns4xIj9oGrKSz7XTQiJx2zgh7AcNke4w=
@@ -118,8 +120,6 @@ github.com/dvyukov/go-fuzz v0.0.0-20200318091601-be3528f3a813/go.mod h1:11Gm+ccJ
 github.com/eapache/go-resiliency v1.1.0/go.mod h1:kFI+JgMyC7bLPUVY133qvEBtVayf5mFgVsvEsIPBvNs=
 github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21/go.mod h1:+020luEh2TKB4/GOp8oxxtq0Daoen/Cii55CzbTV6DU=
 github.com/eapache/queue v1.1.0/go.mod h1:6eCeP0CKFpHLu8blIFXhExK/dRa7WDZfr6jVFPTqq+I=
-github.com/edsrzf/mmap-go v1.1.0 h1:6EUwBLQ/Mcr1EYLE4Tn1VdW1A4ckqCQWZBw8Hr0kjpQ=
-github.com/edsrzf/mmap-go v1.1.0/go.mod h1:19H/e8pUPLicwkyNgOykDXkJ9F0MHE+Z52B8EIth78Q=
 github.com/elazarl/go-bindata-assetfs v1.0.0/go.mod h1:v+YaWX3bdea5J/mo8dSETolEo7R71Vk1u8bnjau5yw4=
 github.com/elliotchance/orderedmap v1.4.0 h1:wZtfeEONCbx6in1CZyE6bELEt/vFayMvsxqI5SgsR+A=
 github.com/elliotchance/orderedmap v1.4.0/go.mod h1:wsDwEaX5jEoyhbs7x93zk2H/qv0zwuhg4inXhDkYqys=
diff --git a/mmap_span/mmap_span.go b/mmap_span/mmap_span.go
index ee9eca6e10..e5538e593b 100644
--- a/mmap_span/mmap_span.go
+++ b/mmap_span/mmap_span.go
@@ -23,7 +23,7 @@ func (ms *MMapSpan) Flush() (errs []error) {
 	ms.mu.Lock()
 	defer ms.mu.Unlock()
 	for _, mMap := range ms.mMaps {
-		err := mMap.Flush()
+		err := mMap.FlushAsync() // ms.Close does blocking flush
 		if err != nil {
 			errs = append(errs, err)
 		}

From 32d30866019509e2735ccf5d410ba85f534226dc Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Tue, 21 Jun 2022 08:47:16 +0600
Subject: [PATCH 06/19] FlushAsyncAt method

---
 mmap_span/mmap_span.go | 13 ++++++++++++-
 storage/mmap.go        |  2 +-
 torrent.go             |  1 +
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/mmap_span/mmap_span.go b/mmap_span/mmap_span.go
index e5538e593b..9ae2162973 100644
--- a/mmap_span/mmap_span.go
+++ b/mmap_span/mmap_span.go
@@ -19,7 +19,7 @@ func (ms *MMapSpan) Append(mMap mmap.MMap) {
 	ms.mMaps = append(ms.mMaps, mMap)
 }
 
-func (ms *MMapSpan) Flush() (errs []error) {
+func (ms *MMapSpan) FlushAsync() (errs []error) {
 	ms.mu.Lock()
 	defer ms.mu.Unlock()
 	for _, mMap := range ms.mMaps {
@@ -63,6 +63,17 @@ func (me *MMapSpan) InitIndex() {
 	// log.Printf("made mmapspan index: %v", me.segmentLocater)
 }
 
+func (ms *MMapSpan) FlushAt(p []byte, off int64) (err error) {
+	ms.mu.Lock()
+	defer ms.mu.Unlock()
+	ms.segmentLocater.Locate(segments.Extent{off, int64(len(p))}, func(i int, e segments.Extent) bool {
+		//TODO: OS knows which pages are dirty,
+		_ = ms.mMaps[i].FlushAsync()
+		return true
+	})
+	return nil
+}
+
 func (ms *MMapSpan) ReadAt(p []byte, off int64) (n int, err error) {
 	// log.Printf("reading %v bytes at %v", len(p), off)
 	ms.mu.RLock()
diff --git a/storage/mmap.go b/storage/mmap.go
index a9d922ac20..281b7adbfb 100644
--- a/storage/mmap.go
+++ b/storage/mmap.go
@@ -72,7 +72,7 @@ func (ts *mmapTorrentStorage) Close() error {
 	return nil
 }
 func (ts *mmapTorrentStorage) Flush() error {
-	errs := ts.span.Flush()
+	errs := ts.span.FlushAsync()
 	if len(errs) > 0 {
 		return errs[0]
 	}
diff --git a/torrent.go b/torrent.go
index f8af697ca7..66f9197dce 100644
--- a/torrent.go
+++ b/torrent.go
@@ -2088,6 +2088,7 @@ func (t *Torrent) onPieceCompleted(piece pieceIndex) {
 		conn.have(piece)
 		t.maybeDropMutuallyCompletePeer(&conn.Peer)
 	}
+	t.piece(piece).Storage().MarkComplete()
 }
 
 // Called when a piece is found to be not complete.

From 259201f4b30197970ce6086a4a5ea75b1e6af6c5 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Tue, 21 Jun 2022 08:52:56 +0600
Subject: [PATCH 07/19] FlushAsyncAt method

---
 go.mod                 | 2 +-
 go.sum                 | 4 ++--
 mmap_span/mmap_span.go | 3 ++-
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/go.mod b/go.mod
index 080b8926b9..05c719f18b 100644
--- a/go.mod
+++ b/go.mod
@@ -2,7 +2,7 @@ module github.com/anacrolix/torrent
 
 go 1.18
 
-replace github.com/edsrzf/mmap-go => github.com/AskAlexSharov/mmap-go v1.2.0
+replace github.com/edsrzf/mmap-go => github.com/AskAlexSharov/mmap-go v1.4.0
 
 require (
 	crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508
diff --git a/go.sum b/go.sum
index 7ce14ab7c8..ddab658054 100644
--- a/go.sum
+++ b/go.sum
@@ -6,8 +6,8 @@ crawshaw.io/sqlite v0.3.2/go.mod h1:igAO5JulrQ1DbdZdtVq48mnZUBAPOeFzer7VhDWNtW4=
 crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508 h1:fILCBBFnjnrQ0whVJlGhfv1E/QiaFDNtGFBObEVRnYg=
 crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508/go.mod h1:igAO5JulrQ1DbdZdtVq48mnZUBAPOeFzer7VhDWNtW4=
 filippo.io/edwards25519 v1.0.0-rc.1 h1:m0VOOB23frXZvAOK44usCgLWvtsxIoMCTBGJZlpmGfU=
-github.com/AskAlexSharov/mmap-go v1.2.0 h1:5Tyz/L4+o3ywXN+50pq7DNAiu/YSwBPKeB2h1vJka80=
-github.com/AskAlexSharov/mmap-go v1.2.0/go.mod h1:19H/e8pUPLicwkyNgOykDXkJ9F0MHE+Z52B8EIth78Q=
+github.com/AskAlexSharov/mmap-go v1.4.0 h1:+4YYliojbn45IDAxNb4CqnEvOJIkUKSlVsn5x+ED4FI=
+github.com/AskAlexSharov/mmap-go v1.4.0/go.mod h1:19H/e8pUPLicwkyNgOykDXkJ9F0MHE+Z52B8EIth78Q=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/Julusian/godocdown v0.0.0-20170816220326-6d19f8ff2df8/go.mod h1:INZr5t32rG59/5xeltqoCJoNY7e5x/3xoY9WSWVWg74=
 github.com/RoaringBitmap/roaring v0.4.7/go.mod h1:8khRDP4HmeXns4xIj9oGrKSz7XTQiJx2zgh7AcNke4w=
diff --git a/mmap_span/mmap_span.go b/mmap_span/mmap_span.go
index 9ae2162973..7400f6f161 100644
--- a/mmap_span/mmap_span.go
+++ b/mmap_span/mmap_span.go
@@ -68,7 +68,7 @@ func (ms *MMapSpan) FlushAt(p []byte, off int64) (err error) {
 	defer ms.mu.Unlock()
 	ms.segmentLocater.Locate(segments.Extent{off, int64(len(p))}, func(i int, e segments.Extent) bool {
 		//TODO: OS knows which pages are dirty,
-		_ = ms.mMaps[i].FlushAsync()
+		_ = ms.mMaps[i].FlushAsyncAt(e.Start, e.Length)
 		return true
 	})
 	return nil
@@ -96,6 +96,7 @@ func (ms *MMapSpan) locateCopy(copyArgs func(remainingArgument, mmapped []byte)
 		_n := copyBytes(copyArgs(p, mMapBytes))
 		p = p[_n:]
 		n += _n
+
 		if segments.Int(_n) != e.Length {
 			panic(fmt.Sprintf("did %d bytes, expected to do %d", _n, e.Length))
 		}

From 320081ca2c97c7a8e617811b13d20b721f0d2edb Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Tue, 21 Jun 2022 08:56:05 +0600
Subject: [PATCH 08/19] FlushAsyncAt method

---
 torrent.go | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/torrent.go b/torrent.go
index 66f9197dce..e53b897264 100644
--- a/torrent.go
+++ b/torrent.go
@@ -2462,11 +2462,7 @@ func (t *Torrent) pieceRequestIndexOffset(piece pieceIndex) RequestIndex {
 }
 
 func (t *Torrent) updateComplete() {
-	before := t.Complete.Bool()
 	t.Complete.SetBool(t.haveAllPieces())
-	if !before && t.storage.Flush != nil && t.Complete.Bool() {
-		_ = t.storage.Flush()
-	}
 }
 
 func (t *Torrent) cancelRequest(r RequestIndex) *Peer {

From 2acf8481d855f3a2ae5913aa267f7264b2490558 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Tue, 21 Jun 2022 09:00:17 +0600
Subject: [PATCH 09/19] FlushAsyncAt method

---
 go.mod | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/go.mod b/go.mod
index 05c719f18b..68f61d3d91 100644
--- a/go.mod
+++ b/go.mod
@@ -2,8 +2,6 @@ module github.com/anacrolix/torrent
 
 go 1.18
 
-replace github.com/edsrzf/mmap-go => github.com/AskAlexSharov/mmap-go v1.4.0
-
 require (
 	crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508
 	github.com/RoaringBitmap/roaring v1.0.1-0.20220510143707-3f418c4f42a4
@@ -30,7 +28,7 @@ require (
 	github.com/bradfitz/iter v0.0.0-20191230175014-e8f45d346db8
 	github.com/davecgh/go-spew v1.1.1
 	github.com/dustin/go-humanize v1.0.0
-	github.com/edsrzf/mmap-go v1.1.0
+	github.com/AskAlexSharov/mmap-go v1.4.0
 	github.com/elliotchance/orderedmap v1.4.0
 	github.com/frankban/quicktest v1.14.3
 	github.com/fsnotify/fsnotify v1.5.1

From 8af4a58c6876b0b5024a48b07054541df761d4f7 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Tue, 21 Jun 2022 09:03:21 +0600
Subject: [PATCH 10/19] FlushAsyncAt method

---
 cmd/torrent-verify/main.go | 2 +-
 go.mod                     | 2 +-
 go.sum                     | 4 ++--
 iplist/packed.go           | 2 +-
 mmap_span/mmap_span.go     | 2 +-
 storage/mmap.go            | 2 +-
 6 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/cmd/torrent-verify/main.go b/cmd/torrent-verify/main.go
index e945f12f6d..4e3f069879 100644
--- a/cmd/torrent-verify/main.go
+++ b/cmd/torrent-verify/main.go
@@ -9,8 +9,8 @@ import (
 	"os"
 	"path/filepath"
 
+	"github.com/AskAlexSharov/mmap-go"
 	"github.com/anacrolix/tagflag"
-	"github.com/edsrzf/mmap-go"
 
 	"github.com/anacrolix/torrent/metainfo"
 	"github.com/anacrolix/torrent/mmap_span"
diff --git a/go.mod b/go.mod
index 68f61d3d91..4129329980 100644
--- a/go.mod
+++ b/go.mod
@@ -28,7 +28,6 @@ require (
 	github.com/bradfitz/iter v0.0.0-20191230175014-e8f45d346db8
 	github.com/davecgh/go-spew v1.1.1
 	github.com/dustin/go-humanize v1.0.0
-	github.com/AskAlexSharov/mmap-go v1.4.0
 	github.com/elliotchance/orderedmap v1.4.0
 	github.com/frankban/quicktest v1.14.3
 	github.com/fsnotify/fsnotify v1.5.1
@@ -49,6 +48,7 @@ require (
 )
 
 require (
+	github.com/AskAlexSharov/mmap-go v1.5.0 // indirect
 	github.com/alexflint/go-scalar v1.1.0 // indirect
 	github.com/anacrolix/mmsg v1.0.0 // indirect
 	github.com/anacrolix/stm v0.3.0 // indirect
diff --git a/go.sum b/go.sum
index ddab658054..6f8ebf9a25 100644
--- a/go.sum
+++ b/go.sum
@@ -6,8 +6,8 @@ crawshaw.io/sqlite v0.3.2/go.mod h1:igAO5JulrQ1DbdZdtVq48mnZUBAPOeFzer7VhDWNtW4=
 crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508 h1:fILCBBFnjnrQ0whVJlGhfv1E/QiaFDNtGFBObEVRnYg=
 crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508/go.mod h1:igAO5JulrQ1DbdZdtVq48mnZUBAPOeFzer7VhDWNtW4=
 filippo.io/edwards25519 v1.0.0-rc.1 h1:m0VOOB23frXZvAOK44usCgLWvtsxIoMCTBGJZlpmGfU=
-github.com/AskAlexSharov/mmap-go v1.4.0 h1:+4YYliojbn45IDAxNb4CqnEvOJIkUKSlVsn5x+ED4FI=
-github.com/AskAlexSharov/mmap-go v1.4.0/go.mod h1:19H/e8pUPLicwkyNgOykDXkJ9F0MHE+Z52B8EIth78Q=
+github.com/AskAlexSharov/mmap-go v1.5.0 h1:jSaqLONrUIJOSzQGyszDMbF6q9rHrVhxwcPxrw6Lyhk=
+github.com/AskAlexSharov/mmap-go v1.5.0/go.mod h1:ph1xIqkS6JOQQoBg9LKEf/IXnO0zfOnU0FJyPbFf4rQ=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/Julusian/godocdown v0.0.0-20170816220326-6d19f8ff2df8/go.mod h1:INZr5t32rG59/5xeltqoCJoNY7e5x/3xoY9WSWVWg74=
 github.com/RoaringBitmap/roaring v0.4.7/go.mod h1:8khRDP4HmeXns4xIj9oGrKSz7XTQiJx2zgh7AcNke4w=
diff --git a/iplist/packed.go b/iplist/packed.go
index 5ae1faea2b..8944af8466 100644
--- a/iplist/packed.go
+++ b/iplist/packed.go
@@ -10,7 +10,7 @@ import (
 	"net"
 	"os"
 
-	"github.com/edsrzf/mmap-go"
+	"github.com/AskAlexSharov/mmap-go"
 )
 
 // The packed format is an 8 byte integer of the number of ranges. Then 20
diff --git a/mmap_span/mmap_span.go b/mmap_span/mmap_span.go
index 7400f6f161..60503d558c 100644
--- a/mmap_span/mmap_span.go
+++ b/mmap_span/mmap_span.go
@@ -5,8 +5,8 @@ import (
 	"io"
 	"sync"
 
+	"github.com/AskAlexSharov/mmap-go"
 	"github.com/anacrolix/torrent/segments"
-	"github.com/edsrzf/mmap-go"
 )
 
 type MMapSpan struct {
diff --git a/storage/mmap.go b/storage/mmap.go
index 281b7adbfb..b545fe5387 100644
--- a/storage/mmap.go
+++ b/storage/mmap.go
@@ -10,8 +10,8 @@ import (
 	"os"
 	"path/filepath"
 
+	"github.com/AskAlexSharov/mmap-go"
 	"github.com/anacrolix/missinggo/v2"
-	"github.com/edsrzf/mmap-go"
 
 	"github.com/anacrolix/torrent/metainfo"
 	"github.com/anacrolix/torrent/mmap_span"

From 6e9f2d01888c4eaf4fa8cfd7615b69252f31d910 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Tue, 21 Jun 2022 09:03:34 +0600
Subject: [PATCH 11/19] FlushAsyncAt method

---
 go.mod | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/go.mod b/go.mod
index 4129329980..948e4ee382 100644
--- a/go.mod
+++ b/go.mod
@@ -4,6 +4,7 @@ go 1.18
 
 require (
 	crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508
+	github.com/AskAlexSharov/mmap-go v1.5.0
 	github.com/RoaringBitmap/roaring v1.0.1-0.20220510143707-3f418c4f42a4
 	github.com/ajwerner/btree v0.0.0-20211221152037-f427b3e689c0
 	github.com/alexflint/go-arg v1.4.2
@@ -48,7 +49,6 @@ require (
 )
 
 require (
-	github.com/AskAlexSharov/mmap-go v1.5.0 // indirect
 	github.com/alexflint/go-scalar v1.1.0 // indirect
 	github.com/anacrolix/mmsg v1.0.0 // indirect
 	github.com/anacrolix/stm v0.3.0 // indirect

From df962eb34f0f1285a4e26bb16d758a88fc035682 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Fri, 1 Jul 2022 11:36:28 +0600
Subject: [PATCH 12/19] save

---
 cmd/torrent-verify/main.go |  2 +-
 go.mod                     |  2 +-
 go.sum                     |  4 ++--
 iplist/packed.go           |  2 +-
 mmap_span/mmap_span.go     | 17 +++--------------
 piece.go                   |  4 ++++
 storage/mmap.go            |  4 ++--
 torrent.go                 |  3 +++
 8 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/cmd/torrent-verify/main.go b/cmd/torrent-verify/main.go
index 4e3f069879..e945f12f6d 100644
--- a/cmd/torrent-verify/main.go
+++ b/cmd/torrent-verify/main.go
@@ -9,8 +9,8 @@ import (
 	"os"
 	"path/filepath"
 
-	"github.com/AskAlexSharov/mmap-go"
 	"github.com/anacrolix/tagflag"
+	"github.com/edsrzf/mmap-go"
 
 	"github.com/anacrolix/torrent/metainfo"
 	"github.com/anacrolix/torrent/mmap_span"
diff --git a/go.mod b/go.mod
index cc7cf1f20c..7d56c415fe 100644
--- a/go.mod
+++ b/go.mod
@@ -4,7 +4,6 @@ go 1.18
 
 require (
 	crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508
-	github.com/AskAlexSharov/mmap-go v1.5.0
 	github.com/RoaringBitmap/roaring v1.0.1-0.20220510143707-3f418c4f42a4
 	github.com/ajwerner/btree v0.0.0-20211221152037-f427b3e689c0
 	github.com/alexflint/go-arg v1.4.2
@@ -29,6 +28,7 @@ require (
 	github.com/bradfitz/iter v0.0.0-20191230175014-e8f45d346db8
 	github.com/davecgh/go-spew v1.1.1
 	github.com/dustin/go-humanize v1.0.0
+	github.com/edsrzf/mmap-go v1.0.0
 	github.com/elliotchance/orderedmap v1.4.0
 	github.com/frankban/quicktest v1.14.3
 	github.com/fsnotify/fsnotify v1.5.1
diff --git a/go.sum b/go.sum
index 3348e7f3d5..ef3277c886 100644
--- a/go.sum
+++ b/go.sum
@@ -6,8 +6,6 @@ crawshaw.io/sqlite v0.3.2/go.mod h1:igAO5JulrQ1DbdZdtVq48mnZUBAPOeFzer7VhDWNtW4=
 crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508 h1:fILCBBFnjnrQ0whVJlGhfv1E/QiaFDNtGFBObEVRnYg=
 crawshaw.io/sqlite v0.3.3-0.20210127221821-98b1f83c5508/go.mod h1:igAO5JulrQ1DbdZdtVq48mnZUBAPOeFzer7VhDWNtW4=
 filippo.io/edwards25519 v1.0.0-rc.1 h1:m0VOOB23frXZvAOK44usCgLWvtsxIoMCTBGJZlpmGfU=
-github.com/AskAlexSharov/mmap-go v1.5.0 h1:jSaqLONrUIJOSzQGyszDMbF6q9rHrVhxwcPxrw6Lyhk=
-github.com/AskAlexSharov/mmap-go v1.5.0/go.mod h1:ph1xIqkS6JOQQoBg9LKEf/IXnO0zfOnU0FJyPbFf4rQ=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/Julusian/godocdown v0.0.0-20170816220326-6d19f8ff2df8/go.mod h1:INZr5t32rG59/5xeltqoCJoNY7e5x/3xoY9WSWVWg74=
 github.com/RoaringBitmap/roaring v0.4.7/go.mod h1:8khRDP4HmeXns4xIj9oGrKSz7XTQiJx2zgh7AcNke4w=
@@ -120,6 +118,8 @@ github.com/dvyukov/go-fuzz v0.0.0-20200318091601-be3528f3a813/go.mod h1:11Gm+ccJ
 github.com/eapache/go-resiliency v1.1.0/go.mod h1:kFI+JgMyC7bLPUVY133qvEBtVayf5mFgVsvEsIPBvNs=
 github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21/go.mod h1:+020luEh2TKB4/GOp8oxxtq0Daoen/Cii55CzbTV6DU=
 github.com/eapache/queue v1.1.0/go.mod h1:6eCeP0CKFpHLu8blIFXhExK/dRa7WDZfr6jVFPTqq+I=
+github.com/edsrzf/mmap-go v1.0.0 h1:CEBF7HpRnUCSJgGUb5h1Gm7e3VkmVDrR8lvWVLtrOFw=
+github.com/edsrzf/mmap-go v1.0.0/go.mod h1:YO35OhQPt3KJa3ryjFM5Bs14WD66h8eGKpfaBNrHW5M=
 github.com/elazarl/go-bindata-assetfs v1.0.0/go.mod h1:v+YaWX3bdea5J/mo8dSETolEo7R71Vk1u8bnjau5yw4=
 github.com/elliotchance/orderedmap v1.4.0 h1:wZtfeEONCbx6in1CZyE6bELEt/vFayMvsxqI5SgsR+A=
 github.com/elliotchance/orderedmap v1.4.0/go.mod h1:wsDwEaX5jEoyhbs7x93zk2H/qv0zwuhg4inXhDkYqys=
diff --git a/iplist/packed.go b/iplist/packed.go
index 8944af8466..5ae1faea2b 100644
--- a/iplist/packed.go
+++ b/iplist/packed.go
@@ -10,7 +10,7 @@ import (
 	"net"
 	"os"
 
-	"github.com/AskAlexSharov/mmap-go"
+	"github.com/edsrzf/mmap-go"
 )
 
 // The packed format is an 8 byte integer of the number of ranges. Then 20
diff --git a/mmap_span/mmap_span.go b/mmap_span/mmap_span.go
index 60503d558c..438c54ba8d 100644
--- a/mmap_span/mmap_span.go
+++ b/mmap_span/mmap_span.go
@@ -5,8 +5,8 @@ import (
 	"io"
 	"sync"
 
-	"github.com/AskAlexSharov/mmap-go"
 	"github.com/anacrolix/torrent/segments"
+	"github.com/edsrzf/mmap-go"
 )
 
 type MMapSpan struct {
@@ -19,11 +19,11 @@ func (ms *MMapSpan) Append(mMap mmap.MMap) {
 	ms.mMaps = append(ms.mMaps, mMap)
 }
 
-func (ms *MMapSpan) FlushAsync() (errs []error) {
+func (ms *MMapSpan) Flush() (errs []error) {
 	ms.mu.Lock()
 	defer ms.mu.Unlock()
 	for _, mMap := range ms.mMaps {
-		err := mMap.FlushAsync() // ms.Close does blocking flush
+		err := mMap.Flush() // ms.Close does blocking flush
 		if err != nil {
 			errs = append(errs, err)
 		}
@@ -63,17 +63,6 @@ func (me *MMapSpan) InitIndex() {
 	// log.Printf("made mmapspan index: %v", me.segmentLocater)
 }
 
-func (ms *MMapSpan) FlushAt(p []byte, off int64) (err error) {
-	ms.mu.Lock()
-	defer ms.mu.Unlock()
-	ms.segmentLocater.Locate(segments.Extent{off, int64(len(p))}, func(i int, e segments.Extent) bool {
-		//TODO: OS knows which pages are dirty,
-		_ = ms.mMaps[i].FlushAsyncAt(e.Start, e.Length)
-		return true
-	})
-	return nil
-}
-
 func (ms *MMapSpan) ReadAt(p []byte, off int64) (n int, err error) {
 	// log.Printf("reading %v bytes at %v", len(p), off)
 	ms.mu.RLock()
diff --git a/piece.go b/piece.go
index 680675bab3..ffb58d4732 100644
--- a/piece.go
+++ b/piece.go
@@ -54,6 +54,10 @@ func (p *Piece) Storage() storage.Piece {
 	return p.t.storage.Piece(p.Info())
 }
 
+func (p *Piece) Flush() {
+	_ = p.t.storage.Flush()
+}
+
 func (p *Piece) pendingChunkIndex(chunkIndex chunkIndexType) bool {
 	return !p.chunkIndexDirty(chunkIndex)
 }
diff --git a/storage/mmap.go b/storage/mmap.go
index b545fe5387..a9d922ac20 100644
--- a/storage/mmap.go
+++ b/storage/mmap.go
@@ -10,8 +10,8 @@ import (
 	"os"
 	"path/filepath"
 
-	"github.com/AskAlexSharov/mmap-go"
 	"github.com/anacrolix/missinggo/v2"
+	"github.com/edsrzf/mmap-go"
 
 	"github.com/anacrolix/torrent/metainfo"
 	"github.com/anacrolix/torrent/mmap_span"
@@ -72,7 +72,7 @@ func (ts *mmapTorrentStorage) Close() error {
 	return nil
 }
 func (ts *mmapTorrentStorage) Flush() error {
-	errs := ts.span.FlushAsync()
+	errs := ts.span.Flush()
 	if len(errs) > 0 {
 		return errs[0]
 	}
diff --git a/torrent.go b/torrent.go
index e53b897264..02e4aa2c72 100644
--- a/torrent.go
+++ b/torrent.go
@@ -2008,6 +2008,9 @@ func (t *Torrent) pieceHashed(piece pieceIndex, passed bool, hashIoErr error) {
 		}
 		t.clearPieceTouchers(piece)
 		t.cl.unlock()
+		if p.hasDirtyChunks() {
+			p.Flush() // You can be synchronous here!
+		}
 		err := p.Storage().MarkComplete()
 		if err != nil {
 			t.logger.Printf("%T: error marking piece complete %d: %s", t.storage, piece, err)

From eaa4a6ea7156209b451ac3995eb36b12a3faf819 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Fri, 1 Jul 2022 11:36:56 +0600
Subject: [PATCH 13/19] save

---
 go.mod | 2 +-
 go.sum | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/go.mod b/go.mod
index 7d56c415fe..d63462cb3d 100644
--- a/go.mod
+++ b/go.mod
@@ -28,7 +28,7 @@ require (
 	github.com/bradfitz/iter v0.0.0-20191230175014-e8f45d346db8
 	github.com/davecgh/go-spew v1.1.1
 	github.com/dustin/go-humanize v1.0.0
-	github.com/edsrzf/mmap-go v1.0.0
+	github.com/edsrzf/mmap-go v1.1.0
 	github.com/elliotchance/orderedmap v1.4.0
 	github.com/frankban/quicktest v1.14.3
 	github.com/fsnotify/fsnotify v1.5.1
diff --git a/go.sum b/go.sum
index ef3277c886..e589784c14 100644
--- a/go.sum
+++ b/go.sum
@@ -118,8 +118,8 @@ github.com/dvyukov/go-fuzz v0.0.0-20200318091601-be3528f3a813/go.mod h1:11Gm+ccJ
 github.com/eapache/go-resiliency v1.1.0/go.mod h1:kFI+JgMyC7bLPUVY133qvEBtVayf5mFgVsvEsIPBvNs=
 github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21/go.mod h1:+020luEh2TKB4/GOp8oxxtq0Daoen/Cii55CzbTV6DU=
 github.com/eapache/queue v1.1.0/go.mod h1:6eCeP0CKFpHLu8blIFXhExK/dRa7WDZfr6jVFPTqq+I=
-github.com/edsrzf/mmap-go v1.0.0 h1:CEBF7HpRnUCSJgGUb5h1Gm7e3VkmVDrR8lvWVLtrOFw=
-github.com/edsrzf/mmap-go v1.0.0/go.mod h1:YO35OhQPt3KJa3ryjFM5Bs14WD66h8eGKpfaBNrHW5M=
+github.com/edsrzf/mmap-go v1.1.0 h1:6EUwBLQ/Mcr1EYLE4Tn1VdW1A4ckqCQWZBw8Hr0kjpQ=
+github.com/edsrzf/mmap-go v1.1.0/go.mod h1:19H/e8pUPLicwkyNgOykDXkJ9F0MHE+Z52B8EIth78Q=
 github.com/elazarl/go-bindata-assetfs v1.0.0/go.mod h1:v+YaWX3bdea5J/mo8dSETolEo7R71Vk1u8bnjau5yw4=
 github.com/elliotchance/orderedmap v1.4.0 h1:wZtfeEONCbx6in1CZyE6bELEt/vFayMvsxqI5SgsR+A=
 github.com/elliotchance/orderedmap v1.4.0/go.mod h1:wsDwEaX5jEoyhbs7x93zk2H/qv0zwuhg4inXhDkYqys=

From 0c797270613aaca436e3875b8b04df0150feac88 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Fri, 1 Jul 2022 11:37:54 +0600
Subject: [PATCH 14/19] save

---
 mmap_span/mmap_span.go | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/mmap_span/mmap_span.go b/mmap_span/mmap_span.go
index 438c54ba8d..dd2f628072 100644
--- a/mmap_span/mmap_span.go
+++ b/mmap_span/mmap_span.go
@@ -23,7 +23,7 @@ func (ms *MMapSpan) Flush() (errs []error) {
 	ms.mu.Lock()
 	defer ms.mu.Unlock()
 	for _, mMap := range ms.mMaps {
-		err := mMap.Flush() // ms.Close does blocking flush
+		err := mMap.Flush()
 		if err != nil {
 			errs = append(errs, err)
 		}
@@ -35,11 +35,7 @@ func (ms *MMapSpan) Close() (errs []error) {
 	ms.mu.Lock()
 	defer ms.mu.Unlock()
 	for _, mMap := range ms.mMaps {
-		err := mMap.Flush()
-		if err != nil {
-			errs = append(errs, err)
-		}
-		err = mMap.Unmap()
+		err := mMap.Unmap()
 		if err != nil {
 			errs = append(errs, err)
 		}

From 9e69d94ec258de70189c804b87bc4826cdf26cc2 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Sun, 3 Jul 2022 10:47:09 +0600
Subject: [PATCH 15/19] save

---
 mmap_span/mmap_span.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mmap_span/mmap_span.go b/mmap_span/mmap_span.go
index dd2f628072..d9970be4be 100644
--- a/mmap_span/mmap_span.go
+++ b/mmap_span/mmap_span.go
@@ -20,8 +20,8 @@ func (ms *MMapSpan) Append(mMap mmap.MMap) {
 }
 
 func (ms *MMapSpan) Flush() (errs []error) {
-	ms.mu.Lock()
-	defer ms.mu.Unlock()
+	ms.mu.RLock()
+	defer ms.mu.RUnlock()
 	for _, mMap := range ms.mMaps {
 		err := mMap.Flush()
 		if err != nil {

From cf9f013e0755f73a7a3e6627ee8332443bbf3dd4 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Sun, 3 Jul 2022 10:58:51 +0600
Subject: [PATCH 16/19] save

---
 mmap_span/mmap_span.go | 2 ++
 piece.go               | 4 +++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/mmap_span/mmap_span.go b/mmap_span/mmap_span.go
index d9970be4be..c6a48e0ca9 100644
--- a/mmap_span/mmap_span.go
+++ b/mmap_span/mmap_span.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 	"sync"
+	"time"
 
 	"github.com/anacrolix/torrent/segments"
 	"github.com/edsrzf/mmap-go"
@@ -22,6 +23,7 @@ func (ms *MMapSpan) Append(mMap mmap.MMap) {
 func (ms *MMapSpan) Flush() (errs []error) {
 	ms.mu.RLock()
 	defer ms.mu.RUnlock()
+	defer func(t time.Time) { fmt.Printf("mmap_span.go:26: %s\n", time.Since(t)) }(time.Now())
 	for _, mMap := range ms.mMaps {
 		err := mMap.Flush()
 		if err != nil {
diff --git a/piece.go b/piece.go
index ffb58d4732..3ef3576fdd 100644
--- a/piece.go
+++ b/piece.go
@@ -55,7 +55,9 @@ func (p *Piece) Storage() storage.Piece {
 }
 
 func (p *Piece) Flush() {
-	_ = p.t.storage.Flush()
+	if p.t.storage.Flush != nil {
+		_ = p.t.storage.Flush()
+	}
 }
 
 func (p *Piece) pendingChunkIndex(chunkIndex chunkIndexType) bool {

From a79295e9dd67d48e140512f89c91a455d56a6be5 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Tue, 5 Jul 2022 09:41:59 +0600
Subject: [PATCH 17/19] save

---
 torrent.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/torrent.go b/torrent.go
index 02e4aa2c72..5b4d3b4bfb 100644
--- a/torrent.go
+++ b/torrent.go
@@ -2007,8 +2007,9 @@ func (t *Torrent) pieceHashed(piece pieceIndex, passed bool, hashIoErr error) {
 			c._stats.incrementPiecesDirtiedGood()
 		}
 		t.clearPieceTouchers(piece)
+		hasDirty := p.hasDirtyChunks()
 		t.cl.unlock()
-		if p.hasDirtyChunks() {
+		if hasDirty {
 			p.Flush() // You can be synchronous here!
 		}
 		err := p.Storage().MarkComplete()

From ce57a482f970bd7b7e858569c7acef3b6b5759b8 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Thu, 7 Jul 2022 10:33:21 +0600
Subject: [PATCH 18/19] save

---
 mmap_span/mmap_span.go | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mmap_span/mmap_span.go b/mmap_span/mmap_span.go
index c6a48e0ca9..d9970be4be 100644
--- a/mmap_span/mmap_span.go
+++ b/mmap_span/mmap_span.go
@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"io"
 	"sync"
-	"time"
 
 	"github.com/anacrolix/torrent/segments"
 	"github.com/edsrzf/mmap-go"
@@ -23,7 +22,6 @@ func (ms *MMapSpan) Append(mMap mmap.MMap) {
 func (ms *MMapSpan) Flush() (errs []error) {
 	ms.mu.RLock()
 	defer ms.mu.RUnlock()
-	defer func(t time.Time) { fmt.Printf("mmap_span.go:26: %s\n", time.Since(t)) }(time.Now())
 	for _, mMap := range ms.mMaps {
 		err := mMap.Flush()
 		if err != nil {

From a4a87d5a987220357bd6b68c6437a5440c072b77 Mon Sep 17 00:00:00 2001
From: "alex.sharov" <AskAlexSharov@gmail.com>
Date: Thu, 7 Jul 2022 10:38:25 +0600
Subject: [PATCH 19/19] save

---
 torrent.go | 1 -
 1 file changed, 1 deletion(-)

diff --git a/torrent.go b/torrent.go
index 5b4d3b4bfb..e53b6bef23 100644
--- a/torrent.go
+++ b/torrent.go
@@ -2092,7 +2092,6 @@ func (t *Torrent) onPieceCompleted(piece pieceIndex) {
 		conn.have(piece)
 		t.maybeDropMutuallyCompletePeer(&conn.Peer)
 	}
-	t.piece(piece).Storage().MarkComplete()
 }
 
 // Called when a piece is found to be not complete.