add statfsmore call to get filesystem mount ids

c_defs_linux.go

@@ -9,7 +9,7 @@
 package scoutfs
 
 // use this to generate the types for scoutfs:
-// go tool cgo -godefs c_defs.go >scoutfsdefs.go
+// go tool cgo -godefs c_defs_linux.go >scoutfsdefs.go
 
 // #include <unistd.h>
 // #include <stdio.h>
@@ -46,6 +46,7 @@ package scoutfs
 // typedef struct scoutfs_ioctl_setattr_more scoutfs_ioctl_setattr_more_t;
 // typedef struct scoutfs_ioctl_listxattr_hidden scoutfs_ioctl_listxattr_hidden_t;
 // typedef struct scoutfs_ioctl_find_xattrs scoutfs_ioctl_find_xattrs_t;
+// typedef struct scoutfs_ioctl_statfs_more scoutfs_ioctl_statfs_more_t;
 import "C"
 
 const IOCQUERYINODES = C.SCOUTFS_IOC_WALK_INODES
@@ -57,6 +58,7 @@ const IOCDATAWAITING = C.SCOUTFS_IOC_DATA_WAITING
 const IOCSETATTRMORE = C.SCOUTFS_IOC_SETATTR_MORE
 const IOCLISTXATTRHIDDEN = C.SCOUTFS_IOC_LISTXATTR_HIDDEN
 const IOCFINDXATTRS = C.SCOUTFS_IOC_FIND_XATTRS
+const IOCSTATFSMORE = C.SCOUTFS_IOC_STATFS_MORE
 
 const QUERYINODESMETASEQ = C.SCOUTFS_IOC_WALK_INODES_META_SEQ
 const QUERYINODESDATASEQ = C.SCOUTFS_IOC_WALK_INODES_DATA_SEQ
@@ -76,3 +78,6 @@ type dataWaiting C.scoutfs_ioctl_data_waiting_t
 type setattrMore C.scoutfs_ioctl_setattr_more_t
 type listXattrHidden C.scoutfs_ioctl_listxattr_hidden_t
 type findXattrs C.scoutfs_ioctl_find_xattrs_t
+type statfsMore C.scoutfs_ioctl_statfs_more_t
+
+const sizeofstatfsMore = C.sizeof_scoutfs_ioctl_statfs_more_t

examples/statfsmore/main.go

@@ -0,0 +1,37 @@
+// Copyright (c) 2018 Versity Software, Inc.
+//
+// Use of this source code is governed by a BSD-3-Clause license
+// that can be found in the LICENSE file in the root of the source
+// tree.
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+
+	scoutfs "github.com/versity/scoutfs-go"
+)
+
+func main() {
+	if len(os.Args) != 2 || os.Args[1] == "-h" {
+		fmt.Fprintln(os.Stderr, "usage:", os.Args[0], "<filepath>")
+		os.Exit(1)
+	}
+
+	f, err := os.Open(os.Args[1])
+	if err != nil {
+		log.Fatalf("open %q: %v", os.Args[1], err)
+	}
+	defer f.Close()
+
+	id, err := scoutfs.GetIDs(f)
+	if err != nil {
+		log.Fatalf("error GetIDs: %v", err)
+	}
+
+	fmt.Printf("fsid %016x\n", id.FSID)
+	fmt.Printf("rid  %016x\n", id.RandomID)
+	fmt.Printf("%v\n", id.ShortID)
+}

scoutfs.go

@@ -9,6 +9,7 @@ package scoutfs
 import (
 	"bytes"
 	"encoding/binary"
+	"fmt"
 	"math"
 	"os"
 	"time"
@@ -480,3 +481,33 @@ func bufToStrings(b []byte) []string {
 	}
 	return s
 }
+
+// FSID contains the statfs more info for mounted scoutfs filesystem
+type FSID struct {
+	FSID     uint64
+	RandomID uint64
+	ShortID  string
+}
+
+// GetIDs gets the statfs more filesystem and random id from file handle within
+// scoutfs filesystem
+func GetIDs(f *os.File) (FSID, error) {
+	stfs := statfsMore{Bytes: sizeofstatfsMore}
+
+	_, err := scoutfsctl(f.Fd(), IOCSTATFSMORE, uintptr(unsafe.Pointer(&stfs)))
+	if err != nil {
+		return FSID{}, err
+	}
+	if stfs.Bytes != sizeofstatfsMore {
+		return FSID{}, fmt.Errorf("unexpected return size: %v", stfs.Bytes)
+	}
+
+	short := fmt.Sprintf("f.%v.r.%v",
+		fmt.Sprintf("%016x", stfs.Fsid)[:][:6], fmt.Sprintf("%016x", stfs.Rid)[:][:6])
+
+	return FSID{
+		FSID:     stfs.Fsid,
+		RandomID: stfs.Rid,
+		ShortID:  short,
+	}, nil
+}

scoutfsdefs.go

@@ -12,6 +12,7 @@ const IOCDATAWAITING = 0x80287307
 const IOCSETATTRMORE = 0x40287308
 const IOCLISTXATTRHIDDEN = 0x80187309
 const IOCFINDXATTRS = 0x8020730a
+const IOCSTATFSMORE = 0x8018730b
 
 const QUERYINODESMETASEQ = 0x0
 const QUERYINODESDATASEQ = 0x1
@@ -98,3 +99,10 @@ type findXattrs struct {
 	Nr_inodes	uint16
 	X_pad		[4]uint8
 }
+type statfsMore struct {
+	Bytes	uint64
+	Fsid	uint64
+	Rid	uint64
+}
+
+const sizeofstatfsMore = 0x18