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serve nfs: implement on disk cache for file handles

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This commit is contained in:
Nick Craig-Wood 2024-06-25 16:15:21 +01:00
parent 55b9b3e33a
commit 70e8ad456f
5 changed files with 368 additions and 39 deletions
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3
cmd/nfsmount/nfsmount_test.go
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@ -9,6 +9,7 @@ import (
"github.com/rclone/rclone/vfs/vfscommon"
"github.com/rclone/rclone/vfs/vfstest"
"github.com/stretchr/testify/require"
)
// Return true if the command ran without error
@ -28,5 +29,7 @@ func TestMount(t *testing.T) {
}
sudo = true
}
nfsServerOpt.HandleCacheDir = t.TempDir()
require.NoError(t, nfsServerOpt.HandleCache.Set("disk"))
vfstest.RunTests(t, false, vfscommon.CacheModeWrites, false, mount)
}

136
cmd/serve/nfs/cache.go
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@ -3,7 +3,24 @@
package nfs
import (
"crypto/md5"
"encoding/hex"
"errors"
"fmt"
"math"
"os"
"path"
"path/filepath"
"runtime"
"strings"
"sync"
billy "github.com/go-git/go-billy/v5"
"github.com/rclone/rclone/fs"
"github.com/rclone/rclone/fs/config"
"github.com/rclone/rclone/lib/encoder"
"github.com/rclone/rclone/lib/file"
"github.com/willscott/go-nfs"
nfshelper "github.com/willscott/go-nfs/helpers"
)
@ -25,8 +42,121 @@ type Cache interface {
}
// Set the cache of the handler to the type required by the user
func (h *Handler) setCache() (err error) {
// The default caching handler
h.Cache = nfshelper.NewCachingHandler(h, h.opt.HandleLimit)
func (h *Handler) getCache() (c Cache, err error) {
switch h.opt.HandleCache {
case cacheMemory:
return nfshelper.NewCachingHandler(h, h.opt.HandleLimit), nil
case cacheDisk:
return newDiskHandler(h)
case cacheSymlink:
if runtime.GOOS != "linux" {
return nil, errors.New("can only use symlink cache on Linux")
}
return nil, errors.New("FIXME not implemented yet")
}
return nil, errors.New("unknown handle cache type")
}
// diskHandler implements an on disk NFS file handle cache
type diskHandler struct {
mu sync.RWMutex
cacheDir string
billyFS billy.Filesystem
}
// Create a new disk handler
func newDiskHandler(h *Handler) (dh *diskHandler, err error) {
cacheDir := h.opt.HandleCacheDir
// If cacheDir isn't set then make one from the config
if cacheDir == "" {
// How the VFS was configured
configString := fs.ConfigString(h.vfs.Fs())
// Turn it into a valid OS directory name
dirName := encoder.OS.ToStandardName(configString)
cacheDir = filepath.Join(config.GetCacheDir(), "serve-nfs-handle-cache-"+h.opt.HandleCache.String(), dirName)
}
// Create the cache dir
err = file.MkdirAll(cacheDir, 0700)
if err != nil {
return nil, fmt.Errorf("disk handler mkdir failed: %v", err)
}
dh = &diskHandler{
cacheDir: cacheDir,
billyFS: h.billyFS,
}
fs.Infof("nfs", "Storing handle cache in %q", dh.cacheDir)
return dh, nil
}
// Convert a path to a hash
func hashPath(fullPath string) []byte {
hash := md5.Sum([]byte(fullPath))
return hash[:]
}
// Convert a handle to a path on disk for the handle
func (dh *diskHandler) handleToPath(fh []byte) (cachePath string) {
fhString := hex.EncodeToString(fh)
if len(fhString) <= 4 {
cachePath = filepath.Join(dh.cacheDir, fhString)
} else {
cachePath = filepath.Join(dh.cacheDir, fhString[0:2], fhString[2:4], fhString)
}
return cachePath
}
// ToHandle takes a file and represents it with an opaque handle to reference it.
// In stateless nfs (when it's serving a unix fs) this can be the device + inode
// but we can generalize with a stateful local cache of handed out IDs.
func (dh *diskHandler) ToHandle(f billy.Filesystem, splitPath []string) (fh []byte) {
dh.mu.Lock()
defer dh.mu.Unlock()
fullPath := path.Join(splitPath...)
fh = hashPath(fullPath)
cachePath := dh.handleToPath(fh)
cacheDir := filepath.Dir(cachePath)
err := os.MkdirAll(cacheDir, 0700)
if err != nil {
fs.Errorf("nfs", "Couldn't create cache file handle directory: %v", err)
return fh
}
err = os.WriteFile(cachePath, []byte(fullPath), 0600)
if err != nil {
fs.Errorf("nfs", "Couldn't create cache file handle: %v", err)
return fh
}
return fh
}
var errStaleHandle = &nfs.NFSStatusError{NFSStatus: nfs.NFSStatusStale}
// FromHandle converts from an opaque handle to the file it represents
func (dh *diskHandler) FromHandle(fh []byte) (f billy.Filesystem, splitPath []string, err error) {
dh.mu.RLock()
defer dh.mu.RUnlock()
cachePath := dh.handleToPath(fh)
fullPathBytes, err := os.ReadFile(cachePath)
if err != nil {
fs.Errorf("nfs", "Stale handle %q: %v", cachePath, err)
return nil, nil, errStaleHandle
}
splitPath = strings.Split(string(fullPathBytes), "/")
return dh.billyFS, splitPath, nil
}
// Invalidate the handle passed - used on rename and delete
func (dh *diskHandler) InvalidateHandle(f billy.Filesystem, fh []byte) error {
dh.mu.Lock()
defer dh.mu.Unlock()
cachePath := dh.handleToPath(fh)
err := os.Remove(cachePath)
if err != nil {
fs.Errorf("nfs", "Failed to remove handle %q: %v", cachePath, err)
}
return nil
}
// HandleLimit exports how many file handles can be safely stored by this cache.
func (dh *diskHandler) HandleLimit() int {
return math.MaxInt
}

134
cmd/serve/nfs/cache_test.go Normal file
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@ -0,0 +1,134 @@
//go:build unix
package nfs
import (
"context"
"fmt"
"sync"
"testing"
"github.com/rclone/rclone/fs"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
// Check basic CRUD operations
func testCacheCRUD(t *testing.T, h *Handler, c Cache, fileName string) {
// Check reading a non existent handle returns an error
_, _, err := c.FromHandle([]byte{10})
assert.Error(t, err)
// Write a handle
splitPath := []string{"dir", fileName}
fh := c.ToHandle(h.billyFS, splitPath)
assert.True(t, len(fh) > 0)
// Read the handle back
newFs, newSplitPath, err := c.FromHandle(fh)
require.NoError(t, err)
assert.Equal(t, h.billyFS, newFs)
assert.Equal(t, splitPath, newSplitPath)
// Invalidate the handle
err = c.InvalidateHandle(h.billyFS, fh)
require.NoError(t, err)
// Invalidate the handle twice
err = c.InvalidateHandle(h.billyFS, fh)
require.NoError(t, err)
// Check the handle is gone and returning stale handle error
_, _, err = c.FromHandle(fh)
require.Error(t, err)
assert.Equal(t, errStaleHandle, err)
}
// Thrash the cache operations in parallel on different files
func testCacheThrashDifferent(t *testing.T, h *Handler, c Cache) {
var wg sync.WaitGroup
for i := 0; i < 100; i++ {
i := i
wg.Add(1)
go func() {
defer wg.Done()
testCacheCRUD(t, h, c, fmt.Sprintf("file-%d", i))
}()
}
wg.Wait()
}
// Thrash the cache operations in parallel on the same file
func testCacheThrashSame(t *testing.T, h *Handler, c Cache) {
var wg sync.WaitGroup
for i := 0; i < 100; i++ {
wg.Add(1)
go func() {
defer wg.Done()
// Write a handle
splitPath := []string{"file"}
fh := c.ToHandle(h.billyFS, splitPath)
assert.True(t, len(fh) > 0)
// Read the handle back
newFs, newSplitPath, err := c.FromHandle(fh)
if err != nil {
assert.Equal(t, errStaleHandle, err)
} else {
require.NoError(t, err)
assert.Equal(t, h.billyFS, newFs)
assert.Equal(t, splitPath, newSplitPath)
}
// Invalidate the handle
err = c.InvalidateHandle(h.billyFS, fh)
require.NoError(t, err)
// Check the handle is gone and returning stale handle error
_, _, err = c.FromHandle(fh)
if err != nil {
require.Error(t, err)
assert.Equal(t, errStaleHandle, err)
}
}()
}
wg.Wait()
}
func TestCache(t *testing.T) {
// Quieten the flood of ERROR messages!
ci := fs.GetConfig(context.Background())
oldLogLevel := ci.LogLevel
ci.LogLevel = fs.LogLevelEmergency
defer func() {
ci.LogLevel = oldLogLevel
}()
billyFS := &FS{nil} // place holder billyFS
for _, cacheType := range []handleCache{cacheMemory, cacheDisk} {
cacheType := cacheType
t.Run(cacheType.String(), func(t *testing.T) {
h := &Handler{
billyFS: billyFS,
}
h.opt.HandleLimit = 1000
h.opt.HandleCache = cacheType
h.opt.HandleCacheDir = t.TempDir()
c, err := h.getCache()
require.NoError(t, err)
t.Run("CRUD", func(t *testing.T) {
testCacheCRUD(t, h, c, "file")
})
// NB the default caching handler is not thread safe!
if cacheType != cacheMemory {
t.Run("ThrashDifferent", func(t *testing.T) {
testCacheThrashDifferent(t, h, c)
})
t.Run("ThrashSame", func(t *testing.T) {
testCacheThrashSame(t, h, c)
})
}
})
}
}

18
cmd/serve/nfs/handler.go
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@ -13,32 +13,30 @@ import (
"github.com/rclone/rclone/fs/log"
"github.com/rclone/rclone/vfs"
"github.com/willscott/go-nfs"
nfshelper "github.com/willscott/go-nfs/helpers"
)
// Handler returns a NFS backing that exposes a given file system in response to all mount requests.
type Handler struct {
vfs *vfs.VFS
opt *Options
opt Options
billyFS *FS
Cache
}
// NewHandler creates a handler for the provided filesystem
func NewHandler(vfs *vfs.VFS, opt *Options) (nfs.Handler, error) {
handler := &Handler{
func NewHandler(vfs *vfs.VFS, opt *Options) (handler nfs.Handler, err error) {
h := &Handler{
vfs: vfs,
opt: opt,
opt: *opt,
billyFS: &FS{vfs: vfs},
}
handler.opt.HandleLimit = handler.opt.Limit()
err := handler.setCache()
h.opt.HandleLimit = h.opt.Limit()
h.Cache, err = h.getCache()
if err != nil {
return nil, fmt.Errorf("failed to make cache: %w", err)
}
handler.Cache = nfshelper.NewCachingHandler(handler, handler.opt.HandleLimit)
nfs.SetLogger(&logIntercepter{Level: nfs.DebugLevel})
return handler, nil
return h, nil
}
// Mount backs Mount RPC Requests, allowing for access control policies.
@ -83,7 +81,7 @@ func (h *Handler) HandleLimit() int {
return h.Cache.HandleLimit()
}
// Invalidate the handle passed - used on rename and delete
// InvalidateHandle invalidates the handle passed - used on rename and delete
func (h *Handler) InvalidateHandle(f billy.Filesystem, b []byte) (err error) {
defer log.Trace("nfs", "handle=%X", b)("err=%v", &err)
return h.Cache.InvalidateHandle(f, b)

116
cmd/serve/nfs/nfs.go
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@ -1,16 +1,17 @@
//go:build unix
// Package nfs implements a server to serve a VFS remote over NFSv3 protocol
// Package nfs implements a server to serve a VFS remote over the NFSv3 protocol
//
// There is no authentication available on this server
// and it is served on loopback interface by default.
// There is no authentication available on this server and it is
// served on the loopback interface by default.
//
// This is primarily used for mounting a VFS remote
// in macOS, where FUSE-mounting mechanisms are usually not available.
// This is primarily used for mounting a VFS remote in macOS, where
// FUSE-mounting mechanisms are usually not available.
package nfs
import (
"context"
"strings"
"github.com/rclone/rclone/cmd"
"github.com/rclone/rclone/fs"
@ -31,16 +32,44 @@ var OptionsInfo = fs.Options{{
Name: "nfs_cache_handle_limit",
Default: 1000000,
Help: "max file handles cached simultaneously (min 5)",
}, {
Name: "nfs_cache_type",
Default: cacheMemory,
Help: "Type of NFS handle cache to use",
}, {
Name: "nfs_cache_dir",
Default: "",
Help: "The directory the NFS handle cache will use if set",
}}
func init() {
fs.RegisterGlobalOptions(fs.OptionsInfo{Name: "nfs", Opt: &opt, Options: OptionsInfo})
}
type handleCache = fs.Enum[handleCacheChoices]
const (
cacheMemory handleCache = iota
cacheDisk
cacheSymlink
)
type handleCacheChoices struct{}
func (handleCacheChoices) Choices() []string {
return []string{
cacheMemory: "memory",
cacheDisk: "disk",
cacheSymlink: "symlink",
}
}
// Options contains options for the NFS Server
type Options struct {
ListenAddr string `config:"addr"` // Port to listen on
HandleLimit int `config:"nfs_cache_handle_limit"` // max file handles cached by go-nfs CachingHandler
ListenAddr string `config:"addr"` // Port to listen on
HandleLimit int `config:"nfs_cache_handle_limit"` // max file handles cached by go-nfs CachingHandler
HandleCache handleCache `config:"nfs_cache_type"` // what kind of handle cache to use
HandleCacheDir string `config:"nfs_cache_dir"` // where the handle cache should be stored
}
var opt Options
@ -73,38 +102,73 @@ func Run(command *cobra.Command, args []string) {
var Command = &cobra.Command{
Use: "nfs remote:path",
Short: `Serve the remote as an NFS mount`,
Long: `Create an NFS server that serves the given remote over the network.
Long: strings.ReplaceAll(`Create an NFS server that serves the given remote over the network.
The primary purpose for this command is to enable [mount command](/commands/rclone_mount/) on recent macOS versions where
installing FUSE is very cumbersome.
This implements an NFSv3 server to serve any rclone remote via NFS.
Since this is running on NFSv3, no authentication method is available. Any client
will be able to access the data. To limit access, you can use serve NFS on loopback address
and rely on secure tunnels (such as SSH). For this reason, by default, a random TCP port is chosen and loopback interface is used for the listening address;
meaning that it is only available to the local machine. If you want other machines to access the
NFS mount over local network, you need to specify the listening address and port using ` + "`--addr`" + ` flag.
The primary purpose for this command is to enable the [mount
command](/commands/rclone_mount/) on recent macOS versions where
installing FUSE is very cumbersome.
Modifying files through NFS protocol requires VFS caching. Usually you will need to specify ` + "`--vfs-cache-mode`" + `
in order to be able to write to the mountpoint (full is recommended). If you don't specify VFS cache mode,
the mount will be read-only. Note also that ` + "`--nfs-cache-handle-limit`" + ` controls the maximum number of cached file handles stored by the caching handler.
This should not be set too low or you may experience errors when trying to access files. The default is ` + "`1000000`" + `, but consider lowering this limit if
the server's system resource usage causes problems.
This server does not implement any authentication so any client will be
able to access the data. To limit access, you can use |serve nfs| on
the loopback address or rely on secure tunnels (such as SSH) or use
firewalling.
For this reason, by default, a random TCP port is chosen and the
loopback interface is used for the listening address by default;
meaning that it is only available to the local machine. If you want
other machines to access the NFS mount over local network, you need to
specify the listening address and port using the |--addr| flag.
Modifying files through the NFS protocol requires VFS caching. Usually
you will need to specify |--vfs-cache-mode| in order to be able to
write to the mountpoint (|full| is recommended). If you don't specify
VFS cache mode, the mount will be read-only.
|--nfs-cache-type| controls the type of the NFS handle cache. By
default this is |memory| where new handles will be randomly allocated
when needed. These are stored in memory. If the server is restarted
the handle cache will be lost and connected NFS clients will get stale
handle errors.
|--nfs-cache-type disk| uses an on disk NFS handle cache. Rclone
hashes the path of the object and stores it in a file named after the
hash. These hashes are stored on disk the directory controlled by
|--cache-dir| or the exact directory may be specified with
|--nfs-cache-dir|. Using this means that the NFS server can be
restarted at will without affecting the connected clients.
|--nfs-cache-type symlink| is similar to |--nfs-cache-type disk| in
that it uses an on disk cache, but the cache entries are held as
symlinks. Rclone will use the handle of the underlying file as the NFS
handle which improves performance. This sort of cache can't be backed
up and restored as the underlying handles will change. This is Linux
only.
|--nfs-cache-handle-limit| controls the maximum number of cached NFS
handles stored by the caching handler. This should not be set too low
or you may experience errors when trying to access files. The default
is |1000000|, but consider lowering this limit if the server's system
resource usage causes problems. This is only used by the |memory| type
cache.
To serve NFS over the network use following command:
rclone serve nfs remote: --addr 0.0.0.0:$PORT --vfs-cache-mode=full
We specify a specific port that we can use in the mount command:
To mount the server under Linux/macOS, use the following command:
This specifies a port that can be used in the mount command. To mount
the server under Linux/macOS, use the following command:
mount -t nfs -o port=$PORT,mountport=$PORT,tcp $HOSTNAME:/ path/to/mountpoint
Where ` + "`$PORT`" + ` is the same port number we used in the serve nfs command.
Where |$PORT| is the same port number used in the |serve nfs| command
and |$HOSTNAME| is the network address of the machine that |serve nfs|
was run on.
This feature is only available on Unix platforms.
This command is only available on Unix platforms.
` + vfs.Help(),
`, "|", "`") + vfs.Help(),
Annotations: map[string]string{
"versionIntroduced": "v1.65",
"groups": "Filter",