Merge pull request #2 from versity/ben/get-referring-entries

add support for get-referring-entries

c_defs_linux.go

@@ -53,6 +53,8 @@ package scoutfs
 // typedef struct scoutfs_ioctl_alloc_detail scoutfs_ioctl_alloc_detail_t;
 // typedef struct scoutfs_ioctl_read_xattr_totals scoutfs_ioctl_read_xattr_totals_t;
 // typedef struct scoutfs_ioctl_xattr_total scoutfs_ioctl_xattr_total_t;
+// typedef struct scoutfs_ioctl_get_referring_entries scoutfs_ioctl_get_referring_entries_t;
+// typedef struct scoutfs_ioctl_dirent scoutfs_ioctl_dirent_t;
 //
 // // Go doesnt handle bitfields in structs, so we need to override the scoutfs
 // // struct definition here
@@ -81,6 +83,7 @@ const IOCDATAWAITERR = C.SCOUTFS_IOC_DATA_WAIT_ERR
 const IOCALLOCDETAIL = C.SCOUTFS_IOC_ALLOC_DETAIL
 const IOCMOVEBLOCKS = C.SCOUTFS_IOC_MOVE_BLOCKS
 const IOCREADXATTRTOTALS = C.SCOUTFS_IOC_READ_XATTR_TOTALS
+const IOCGETREFERRINGENTRIES = C.SCOUTFS_IOC_GET_REFERRING_ENTRIES
 
 const QUERYINODESMETASEQ = C.SCOUTFS_IOC_WALK_INODES_META_SEQ
 const QUERYINODESDATASEQ = C.SCOUTFS_IOC_WALK_INODES_DATA_SEQ
@@ -93,6 +96,8 @@ const SEARCHXATTRSOFLAGEND = C.SCOUTFS_SEARCH_XATTRS_OFLAG_END
 
 const MBSTAGEFLG = C.SCOUTFS_IOC_MB_STAGE
 
+const DIRENTFLAGLAST = C.SCOUTFS_IOCTL_DIRENT_FLAG_LAST
+
 type InodesEntry C.scoutfs_ioctl_walk_inodes_entry_t
 type queryInodes C.scoutfs_ioctl_walk_inodes_t
 type inoPath C.scoutfs_ioctl_ino_path_t
@@ -111,6 +116,8 @@ type allocDetailEntry C.scoutfs_ioctl_alloc_detail_entry_t
 type moveBlocks C.scoutfs_ioctl_move_blocks_t
 type readXattrTotals C.scoutfs_ioctl_read_xattr_totals_t
 type xattrTotal C.scoutfs_ioctl_xattr_total_t
+type getReferringEntries C.scoutfs_ioctl_get_referring_entries_t
+type scoutfsDirent C.scoutfs_ioctl_dirent_t
 
 const sizeofstatfsMore = C.sizeof_scoutfs_ioctl_statfs_more_t
 const sizeofxattrTotal = C.sizeof_scoutfs_ioctl_xattr_total_t

examples/getparents/main.go

@@ -0,0 +1,41 @@
+// 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"
+	"strconv"
+
+	scoutfs "github.com/versity/scoutfs-go"
+)
+
+func main() {
+	if len(os.Args) != 3 || os.Args[1] == "-h" {
+		fmt.Fprintln(os.Stderr, "usage:", os.Args[0], "<scoutfs mount point> <inode>")
+		os.Exit(1)
+	}
+
+	f, err := os.Open(os.Args[1])
+	if err != nil {
+		log.Fatalln("error open mount:", err)
+	}
+	defer f.Close()
+
+	u, err := strconv.ParseUint(os.Args[2], 10, 64)
+	if err != nil {
+		log.Fatalln("error parsing inode:", err)
+	}
+
+	s, err := scoutfs.GetParents(f, u, nil)
+	if err != nil {
+		log.Fatalln("error get parents:", err)
+	}
+
+	fmt.Println(s)
+}

scoutfs.go

@@ -10,6 +10,7 @@ import (
 	"bufio"
 	"bytes"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"io"
 	"math"
@@ -23,13 +24,14 @@ import (
 )
 
 const (
-	max64           = 0xffffffffffffffff
+	max64            = 0xffffffffffffffff
-	max32           = 0xffffffff
+	max32            = 0xffffffff
-	pathmax         = 4096
+	pathmax          = 4096
-	sysscoutfs      = "/sys/fs/scoutfs/"
+	sysscoutfs       = "/sys/fs/scoutfs/"
-	statusfile      = "quorum/status"
+	statusfile       = "quorum/status"
-	listattrBufsize = 256 * 1024
+	listattrBufsize  = 256 * 1024
-	scoutfsBS       = 4096
+	getparentBufsize = 4096 * 1024
+	scoutfsBS        = 4096
 	//leaderfile      = "quorum/is_leader"
 )
 
@@ -1019,3 +1021,116 @@ func (t *TotalsGroup) Reset() {
 	t.pos[1] = t.id2
 	t.pos[2] = 0
 }
+
+// Parent contains inode of parent and what the child inode is named within
+// this parent
+type Parent struct {
+	Ino  uint64 // Parent inode
+	Pos  uint64 // Entry directory position in parent
+	Type uint8  // Entry inode type matching DT_ enum values in readdir(3)
+	Ent  string // Entry name as known by parent
+}
+
+// GetParents returns all parents for the given inode
+// An open file within scoutfs is supplied for ioctls
+// (usually just the base mount point directory)
+// If passed in buffer is nil, call will allocate its own buffer.
+func GetParents(dirfd *os.File, ino uint64, b []byte) ([]Parent, error) {
+	if b == nil {
+		b = make([]byte, getparentBufsize)
+	}
+
+	gre := getReferringEntries{}
+
+	gre.Entries_bytes = uint64(len(b))
+	gre.Entries_ptr = uint64(uintptr(unsafe.Pointer(&b[0])))
+	gre.Ino = ino
+
+	var parents []Parent
+
+	for {
+		n, err := scoutfsctl(dirfd, IOCGETREFERRINGENTRIES, unsafe.Pointer(&gre))
+		if err != nil {
+			return nil, err
+		}
+		if n == 0 {
+			break
+		}
+
+		ents, isLast, err := parseDents(b)
+		if err != nil {
+			return nil, err
+		}
+
+		parents = append(parents, ents...)
+		if isLast {
+			break
+		}
+	}
+
+	return parents, nil
+}
+
+func parseDents(b []byte) ([]Parent, bool, error) {
+	r := bytes.NewReader(b)
+	var parents []Parent
+	var isLast bool
+	for {
+		var err error
+		var parent Parent
+		parent, isLast, err = parseDent(r)
+		if errors.Is(err, io.EOF) {
+			break
+		}
+		if err != nil {
+			return nil, false, err
+		}
+		parents = append(parents, parent)
+		if isLast {
+			break
+		}
+		if r.Len() == 0 {
+			break
+		}
+	}
+	return parents, isLast, nil
+}
+
+type dirent struct {
+	Dir_ino     uint64
+	Dir_pos     uint64
+	Ino         uint64
+	Entry_bytes uint16
+	Flags       uint8
+	D_type      uint8
+	Name_len    uint8
+}
+
+func parseDent(r *bytes.Reader) (Parent, bool, error) {
+	var dent dirent
+	err := binary.Read(r, binary.LittleEndian, &dent)
+	if err != nil {
+		return Parent{}, false, err
+	}
+
+	b := new(strings.Builder)
+	_, err = io.CopyN(b, r, int64(dent.Name_len))
+	if err != nil {
+		return Parent{}, false, err
+	}
+
+	pad := int(dent.Entry_bytes) - int(unsafe.Sizeof(dent)) + int(dent.Name_len)
+	for i := 0; i < pad; i++ {
+		_, err = r.ReadByte()
+		if err != nil {
+			return Parent{}, false, err
+		}
+	}
+
+	return Parent{
+		Ino:  dent.Dir_ino,
+		Pos:  dent.Dir_pos,
+		Type: dent.D_type,
+		Ent:  b.String(),
+	}, dent.Flags&DIRENTFLAGLAST == DIRENTFLAGLAST, nil
+}

scoutfsdefs.go

@@ -1,5 +1,5 @@
 // Code generated by cmd/cgo -godefs; DO NOT EDIT.
-// cgo -godefs /workspace/go/src/github.com/versity/scoutfs-go/c_defs_linux.go
+// cgo -godefs c_defs_linux.go
 
 package scoutfs
 
@@ -17,6 +17,7 @@ const IOCDATAWAITERR = 0x4030e80b
 const IOCALLOCDETAIL = 0x4010e80c
 const IOCMOVEBLOCKS = 0x4030e80d
 const IOCREADXATTRTOTALS = 0x4028e80f
+const IOCGETREFERRINGENTRIES = 0x4028e811
 
 const QUERYINODESMETASEQ = 0x0
 const QUERYINODESDATASEQ = 0x1
@@ -29,6 +30,8 @@ const SEARCHXATTRSOFLAGEND = 0x1
 
 const MBSTAGEFLG = 0x1
 
+const DIRENTFLAGLAST = 0x1
+
 type InodesEntry struct {
 	Major	uint64
 	Ino	uint64
@@ -157,6 +160,23 @@ type xattrTotal struct {
 	Total	uint64
 	Count	uint64
 }
+type getReferringEntries struct {
+	Ino		uint64
+	Dir_ino		uint64
+	Dir_pos		uint64
+	Entries_ptr	uint64
+	Entries_bytes	uint64
+}
+type scoutfsDirent struct {
+	Dir_ino		uint64
+	Dir_pos		uint64
+	Ino		uint64
+	Entry_bytes	uint16
+	Flags		uint8
+	D_type		uint8
+	Name_len	uint8
+	Name		[3]uint8
+}
 
 const sizeofstatfsMore = 0x30
 const sizeofxattrTotal = 0x28