[#970] fstree: Handle unsupported O_TMPFILE

Metabase test relied on this behaviour, so fix the test too.

Cherry-picking was hard and did too many conflicts,
here is an original PR:
https://github.com/nspcc-dev/neofs-node/pull/2624

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/local_object_storage/blobstor/fstree/control.go

@@ -16,6 +16,13 @@ func (t *FSTree) Init() error {
 	if err := util.MkdirAllX(t.RootPath, t.Permissions); err != nil {
 		return err
 	}
+	if !t.readOnly {
+		f := newSpecificWriteData(t.fileCounter, t.RootPath, t.Permissions, t.noSync)
+		if f != nil {
+			t.writeData = f
+		}
+	}
+
 	return t.initFileCounter()
 }
 

pkg/local_object_storage/blobstor/fstree/fstree.go

@@ -10,7 +10,6 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
-	"sync/atomic"
 	"syscall"
 	"time"
 
@@ -58,7 +57,7 @@ type FSTree struct {
 	fileCounter        FileCounter
 	fileCounterEnabled bool
 
-	suffix atomic.Uint64
+	writeData func(string, []byte) error
 }
 
 // Info groups the information about file storage.
@@ -96,6 +95,7 @@ func New(opts ...Option) *FSTree {
 	for i := range opts {
 		opts[i](f)
 	}
+	f.writeData = newGenericWriteData(f)
 
 	return f
 }

pkg/local_object_storage/blobstor/fstree/fstree_write_generic.go

@@ -1,5 +1,3 @@
-//go:build !linux
-
 package fstree
 
 import (
@@ -7,24 +5,46 @@ import (
 	"io/fs"
 	"os"
 	"strconv"
+	"sync/atomic"
 	"syscall"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
 )
 
-func (t *FSTree) writeData(p string, data []byte) error {
-	tmpPath := p + "#" + strconv.FormatUint(t.suffix.Add(1), 10)
-	return t.writeAndRename(tmpPath, p, data)
+type genericWriter struct {
+	perm  fs.FileMode
+	flags int
+
+	t      *FSTree
+	suffix atomic.Uint64
+}
+
+func newGenericWriteData(t *FSTree) func(string, []byte) error {
+	flags := os.O_WRONLY | os.O_CREATE | os.O_TRUNC | os.O_EXCL
+	if !t.noSync {
+		flags |= os.O_SYNC
+	}
+	var w = &genericWriter{
+		perm:  t.Permissions,
+		flags: flags,
+		t:     t,
+	}
+	return w.writeData
+}
+
+func (w *genericWriter) writeData(p string, data []byte) error {
+	tmpPath := p + "#" + strconv.FormatUint(w.suffix.Add(1), 10)
+	return w.writeAndRename(tmpPath, p, data)
 }
 
 // writeAndRename opens tmpPath exclusively, writes data to it and renames it to p.
-func (t *FSTree) writeAndRename(tmpPath, p string, data []byte) error {
-	if t.fileCounterEnabled {
-		t.fileGuard.Lock(p)
-		defer t.fileGuard.Unlock(p)
+func (w *genericWriter) writeAndRename(tmpPath, p string, data []byte) error {
+	if w.t.fileCounterEnabled {
+		w.t.fileGuard.Lock(p)
+		defer w.t.fileGuard.Unlock(p)
 	}
 
-	err := t.writeFile(tmpPath, data)
+	err := w.writeFile(tmpPath, data)
 	if err != nil {
 		var pe *fs.PathError
 		if errors.As(err, &pe) {
@@ -37,15 +57,15 @@ func (t *FSTree) writeAndRename(tmpPath, p string, data []byte) error {
 		return err
 	}
 
-	if t.fileCounterEnabled {
-		t.fileCounter.Inc()
+	if w.t.fileCounterEnabled {
+		w.t.fileCounter.Inc()
 		var targetFileExists bool
 		if _, e := os.Stat(p); e == nil {
 			targetFileExists = true
 		}
 		err = os.Rename(tmpPath, p)
 		if err == nil && targetFileExists {
-			t.fileCounter.Dec()
+			w.t.fileCounter.Dec()
 		}
 	} else {
 		err = os.Rename(tmpPath, p)
@@ -53,18 +73,10 @@ func (t *FSTree) writeAndRename(tmpPath, p string, data []byte) error {
 	return err
 }
 
-func (t *FSTree) writeFlags() int {
-	flags := os.O_WRONLY | os.O_CREATE | os.O_TRUNC | os.O_EXCL
-	if t.noSync {
-		return flags
-	}
-	return flags | os.O_SYNC
-}
-
 // writeFile writes data to a file with path p.
 // The code is copied from `os.WriteFile` with minor corrections for flags.
-func (t *FSTree) writeFile(p string, data []byte) error {
-	f, err := os.OpenFile(p, t.writeFlags(), t.Permissions)
+func (w *genericWriter) writeFile(p string, data []byte) error {
+	f, err := os.OpenFile(p, w.flags, w.perm)
 	if err != nil {
 		return err
 	}

pkg/local_object_storage/blobstor/fstree/fstree_write_linux.go

@@ -4,26 +4,52 @@ package fstree
 
 import (
 	"errors"
+	"io/fs"
 	"strconv"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
 	"golang.org/x/sys/unix"
 )
 
-func (t *FSTree) writeData(p string, data []byte) error {
-	err := t.writeFile(p, data)
+type linuxWriter struct {
+	root  string
+	perm  uint32
+	flags int
+
+	counter FileCounter
+}
+
+func newSpecificWriteData(c FileCounter, root string, perm fs.FileMode, noSync bool) func(string, []byte) error {
+	flags := unix.O_WRONLY | unix.O_TMPFILE | unix.O_CLOEXEC
+	if !noSync {
+		flags |= unix.O_DSYNC
+	}
+	fd, err := unix.Open(root, flags, uint32(perm))
+	if err != nil {
+		// Which means that OS-specific writeData can't be created
+		// and FSTree should use the generic one.
+		return nil
+	}
+	_ = unix.Close(fd) // Don't care about error.
+	w := &linuxWriter{
+		root:    root,
+		perm:    uint32(perm),
+		flags:   flags,
+		counter: c,
+	}
+	return w.writeData
+}
+
+func (w *linuxWriter) writeData(p string, data []byte) error {
+	err := w.writeFile(p, data)
 	if errors.Is(err, unix.ENOSPC) {
 		return common.ErrNoSpace
 	}
 	return err
 }
 
-func (t *FSTree) writeFile(p string, data []byte) error {
-	flags := unix.O_WRONLY | unix.O_TMPFILE | unix.O_CLOEXEC
-	if !t.noSync {
-		flags |= unix.O_DSYNC
-	}
-	fd, err := unix.Open(t.RootPath, flags, uint32(t.Permissions))
+func (w *linuxWriter) writeFile(p string, data []byte) error {
+	fd, err := unix.Open(w.root, w.flags, w.perm)
 	if err != nil {
 		return err
 	}
@@ -32,8 +58,10 @@ func (t *FSTree) writeFile(p string, data []byte) error {
 	if err == nil {
 		if n == len(data) {
 			err = unix.Linkat(unix.AT_FDCWD, tmpPath, unix.AT_FDCWD, p, unix.AT_SYMLINK_FOLLOW)
+			if err == nil {
+				w.counter.Inc()
+			}
 			if errors.Is(err, unix.EEXIST) {
-				// https://github.com/nspcc-dev/neofs-node/issues/2563
 				err = nil
 			}
 		} else {

pkg/local_object_storage/blobstor/fstree/fstree_write_specific.go

@@ -0,0 +1,9 @@
+//go:build !linux
+
+package fstree
+
+import "io/fs"
+
+func newSpecificWriteData(_ FileCounter, _ string, _ fs.FileMode, _ bool) func(string, []byte) error {
+	return nil
+}

pkg/local_object_storage/shard/control_test.go

@@ -2,6 +2,7 @@ package shard
 
 import (
 	"context"
+	"fmt"
 	"io/fs"
 	"math"
 	"os"
@@ -11,7 +12,6 @@ import (
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor"
-	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/fstree"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/teststore"
 	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
@@ -145,8 +145,12 @@ func TestRefillMetabaseCorrupted(t *testing.T) {
 	require.NoError(t, sh.Close())
 
 	addr := object.AddressOf(obj)
-	_, err = fsTree.Put(context.Background(), common.PutPrm{Address: addr, RawData: []byte("not an object")})
-	require.NoError(t, err)
+	// This is copied from `fstree.treePath()` to avoid exporting function just for tests.
+	{
+		saddr := addr.Object().EncodeToString() + "." + addr.Container().EncodeToString()
+		p := fmt.Sprintf("%s/%s/%s", fsTree.RootPath, saddr[:2], saddr[2:])
+		require.NoError(t, os.WriteFile(p, []byte("not an object"), fsTree.Permissions))
+	}
 
 	sh = New(
 		WithID(NewIDFromBytes([]byte{})),