Support time_gran and max_pages fuse options

fuse.go

@@ -232,10 +232,17 @@ func initMount(c *Conn, conf *mountConfig) error {
 	}
 	c.proto = proto
 
+	timeGran := uint32(1)
+	if conf.timeGran > 0 {
+		timeGran = conf.timeGran
+	}
+
 	s := &InitResponse{
 		Library:      proto,
 		MaxReadahead: conf.maxReadahead,
 		MaxWrite:     maxWrite,
+		TimeGran:     timeGran,
+		MaxPages:     maxPages,
 		Flags:        InitBigWrites | conf.initFlags,
 	}
 	r.Respond(s)
@@ -1249,10 +1256,14 @@ type InitResponse struct {
 	// Maximum size of a single write operation.
 	// Linux enforces a minimum of 4 KiB.
 	MaxWrite uint32
+	// Filesystem timestamp granularity in nanoseconds.
+	TimeGran uint32
+	// Max pages of a single FUSE message.
+	MaxPages uint16
 }
 
 func (r *InitResponse) String() string {
-	return fmt.Sprintf("Init %v ra=%d fl=%v w=%d", r.Library, r.MaxReadahead, r.Flags, r.MaxWrite)
+	return fmt.Sprintf("Init %v ra=%d fl=%v w=%d tg=%d pg=%d", r.Library, r.MaxReadahead, r.Flags, r.MaxWrite, r.TimeGran, r.MaxPages)
 }
 
 // Respond replies to the request with the given response.
@@ -1264,13 +1275,24 @@ func (r *InitRequest) Respond(resp *InitResponse) {
 	out.MaxReadahead = resp.MaxReadahead
 	out.Flags = uint32(resp.Flags)
 	out.MaxWrite = resp.MaxWrite
+	out.TimeGran = resp.TimeGran
+
+	if r.Kernel.GE(Protocol{7, 28}) {
+		out.Flags |= uint32(InitMaxPages)
+		out.MaxPages = resp.MaxPages
+	}
 
 	// MaxWrite larger than our receive buffer would just lead to
 	// errors on large writes.
 	if out.MaxWrite > maxWrite {
 		out.MaxWrite = maxWrite
 	}
-	r.respond(buf)
+	if r.Kernel.GE(Protocol{7, 23}) {
+		r.respond(buf)
+	} else {
+		// Trucate header struct for older protocol versions.
+		r.respond(buf[:24])
+	}
 }
 
 // A StatfsRequest requests information about the mounted file system.

fuse_darwin.go

@@ -1,5 +1,8 @@
 package fuse
 
+// Max pages per fuse message.
+const maxPages = 32
+
 // Maximum file write size we are prepared to receive from the kernel.
 //
 // This value has to be >=16MB or OSXFUSE (3.4.0 observed) will

fuse_freebsd.go

@@ -1,6 +1,9 @@
 package fuse
 
+// Max pages per fuse message.
+const maxPages = 32
+
 // Maximum file write size we are prepared to receive from the kernel.
 //
 // This number is just a guess.
-const maxWrite = 128 * 1024
+const maxWrite = maxPages * 4096

fuse_kernel.go

@@ -46,7 +46,7 @@ const (
 	protoVersionMinMajor = 7
 	protoVersionMinMinor = 8
 	protoVersionMaxMajor = 7
-	protoVersionMaxMinor = 12
+	protoVersionMaxMinor = 28
 )
 
 const (
@@ -273,6 +273,12 @@ const (
 	InitAsyncDIO        InitFlags = 1 << 15
 	InitWritebackCache  InitFlags = 1 << 16
 	InitNoOpenSupport   InitFlags = 1 << 17
+	InitParallelDirops  InitFlags = 1 << 18
+	InitHandleKillpriv  InitFlags = 1 << 19
+	InitPosixACL        InitFlags = 1 << 20
+	InitAbortError      InitFlags = 1 << 21
+	InitMaxPages        InitFlags = 1 << 22
+	InitCacheSymlinks   InitFlags = 1 << 23
 
 	InitCaseSensitive InitFlags = 1 << 29 // OS X only
 	InitVolRename     InitFlags = 1 << 30 // OS X only
@@ -303,6 +309,12 @@ var initFlagNames = []flagName{
 	{uint32(InitAsyncDIO), "InitAsyncDIO"},
 	{uint32(InitWritebackCache), "InitWritebackCache"},
 	{uint32(InitNoOpenSupport), "InitNoOpenSupport"},
+	{uint32(InitParallelDirops), "InitParallelDirops"},
+	{uint32(InitHandleKillpriv), "InitHandleKillpriv"},
+	{uint32(InitPosixACL), "InitPosixACL"},
+	{uint32(InitAbortError), "InitAbortError"},
+	{uint32(InitMaxPages), "InitMaxPages"},
+	{uint32(InitCacheSymlinks), "InitCacheSymlinks"},
 
 	{uint32(InitCaseSensitive), "InitCaseSensitive"},
 	{uint32(InitVolRename), "InitVolRename"},
@@ -706,8 +718,13 @@ type initOut struct {
 	Minor        uint32
 	MaxReadahead uint32
 	Flags        uint32
-	Unused       uint32
+	_            uint16
+	_            uint16
 	MaxWrite     uint32
+	TimeGran     uint32
+	MaxPages     uint16
+	_            uint16
+	_            [8]uint32
 }
 
 type interruptIn struct {

fuse_linux.go

@@ -1,7 +1,13 @@
 package fuse
 
+// Max pages per fuse message (FUSE_MAX_MAX_PAGES).
+const maxPages = 256
+
 // Maximum file write size we are prepared to receive from the kernel.
 //
 // Linux 4.2.0 has been observed to cap this value at 128kB
 // (FUSE_MAX_PAGES_PER_REQ=32, 4kB pages).
-const maxWrite = 128 * 1024
+//
+// Linux >= 4.20 allows up to FUSE_MAX_MAX_PAGES=256, but defaults to
+// FUSE_DEFAULT_MAX_PAGES_PER_REQ=32.
+const maxWrite = maxPages * 4096

options.go

@@ -14,6 +14,7 @@ func dummyOption(conf *mountConfig) error {
 type mountConfig struct {
 	options          map[string]string
 	maxReadahead     uint32
+	timeGran         uint32
 	initFlags        InitFlags
 	osxfuseLocations []OSXFUSEPaths
 }
@@ -231,6 +232,16 @@ func WritebackCache() MountOption {
 	}
 }
 
+// TimeGran sets the granularity of timestamps in nanoseconds.
+//
+// Default is 1 nanosecond, must be power of 10.
+func TimeGran(n uint32) MountOption {
+	return func(conf *mountConfig) error {
+		conf.timeGran = n
+		return nil
+	}
+}
+
 // OSXFUSEPaths describes the paths used by an installed OSXFUSE
 // version. See OSXFUSELocationV3 for typical values.
 type OSXFUSEPaths struct {