Remove fs.Handle, ramfs.Entry, and all the DeprecatedFileOperations.

More helper structs have been added to the fsutil package to make it easier to
implement fs.InodeOperations and fs.FileOperations.

PiperOrigin-RevId: 229305982
Change-Id: Ib6f8d3862f4216745116857913dbfa351530223b

pkg/abi/linux/fs.go

@@ -22,8 +22,10 @@ const (
 	DEVPTS_SUPER_MAGIC    = 0x00001cd1
 	OVERLAYFS_SUPER_MAGIC = 0x794c7630
 	PIPEFS_MAGIC          = 0x50495045
+	PROC_SUPER_MAGIC      = 0x9fa0
 	RAMFS_MAGIC           = 0x09041934
 	SOCKFS_MAGIC          = 0x534F434B
+	SYSFS_MAGIC           = 0x62656572
 	TMPFS_MAGIC           = 0x01021994
 	V9FS_MAGIC            = 0x01021997
 )

pkg/sentry/fs/BUILD

@@ -94,7 +94,8 @@ go_test(
     deps = [
         ":fs",
         "//pkg/sentry/context",
-        "//pkg/sentry/fs/ramfs/test",
+        "//pkg/sentry/fs/fsutil",
+        "//pkg/sentry/fs/ramfs",
         "//pkg/sentry/fs/tmpfs",
         "//pkg/sentry/kernel/contexttest",
         "//pkg/sentry/usermem",

pkg/sentry/fs/anon/anon.go

@@ -28,16 +28,12 @@ import (
 // with any real filesystem. Some types depend on completely pseudo
 // "anon" inodes (eventfds, epollfds, etc).
 func NewInode(ctx context.Context) *fs.Inode {
-	return fs.NewInode(fsutil.NewSimpleInodeOperations(fsutil.InodeSimpleAttributes{
-		FSType: linux.ANON_INODE_FS_MAGIC,
-		UAttr: fs.WithCurrentTime(ctx, fs.UnstableAttr{
-			Owner: fs.FileOwnerFromContext(ctx),
-			Perms: fs.FilePermissions{
-				User: fs.PermMask{Read: true, Write: true},
-			},
-			Links: 1,
-		}),
-	}), fs.NewNonCachingMountSource(nil, fs.MountSourceFlags{}), fs.StableAttr{
+	iops := &fsutil.SimpleFileInode{
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, fs.RootOwner, fs.FilePermissions{
+			User: fs.PermMask{Read: true, Write: true},
+		}, linux.ANON_INODE_FS_MAGIC),
+	}
+	return fs.NewInode(iops, fs.NewPseudoMountSource(), fs.StableAttr{
 		Type:      fs.Anonymous,
 		DeviceID:  PseudoDevice.DeviceID(),
 		InodeID:   PseudoDevice.NextIno(),

pkg/sentry/fs/ashmem/BUILD

@@ -28,6 +28,7 @@ go_library(
         "//pkg/sentry/usage",
         "//pkg/sentry/usermem",
         "//pkg/syserror",
+        "//pkg/waiter",
     ],
 )
 

pkg/sentry/fs/ashmem/area.go

@@ -28,6 +28,7 @@ import (
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usage"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
 	"gvisor.googlesource.com/gvisor/pkg/syserror"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
 )
 
 const (
@@ -42,9 +43,10 @@ const (
 //
 // +stateify savable
 type Area struct {
-	fsutil.NoFsync                  `state:"nosave"`
-	fsutil.DeprecatedFileOperations `state:"nosave"`
-	fsutil.NotDirReaddir            `state:"nosave"`
+	waiter.AlwaysReady       `state:"nosave"`
+	fsutil.FileNoFsync       `state:"nosave"`
+	fsutil.FileNoopFlush     `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
 
 	ad *Device
 
@@ -98,11 +100,6 @@ func (a *Area) Write(ctx context.Context, file *fs.File, src usermem.IOSequence,
 	return 0, syserror.ENOSYS
 }
 
-// Flush implements fs.FileOperations.Flush.
-func (a *Area) Flush(ctx context.Context, file *fs.File) error {
-	return nil
-}
-
 // ConfigureMMap implements fs.FileOperations.ConfigureMMap.
 func (a *Area) ConfigureMMap(ctx context.Context, file *fs.File, opts *memmap.MMapOpts) error {
 	a.mu.Lock()
@@ -122,8 +119,7 @@ func (a *Area) ConfigureMMap(ctx context.Context, file *fs.File, opts *memmap.MM
 			return syserror.ENOMEM
 		}
 		tmpfsInodeOps := tmpfs.NewInMemoryFile(ctx, usage.Tmpfs, fs.UnstableAttr{}, k)
-		// This is not backed by a real filesystem, so we pass in nil.
-		tmpfsInode := fs.NewInode(tmpfsInodeOps, fs.NewNonCachingMountSource(nil, fs.MountSourceFlags{}), fs.StableAttr{})
+		tmpfsInode := fs.NewInode(tmpfsInodeOps, fs.NewPseudoMountSource(), fs.StableAttr{})
 		dirent := fs.NewDirent(tmpfsInode, namePrefix+"/"+a.name)
 		tmpfsFile, err := tmpfsInode.GetFile(ctx, dirent, fs.FileFlags{Read: true, Write: true})
 		// Drop the extra reference on the Dirent.

pkg/sentry/fs/ashmem/device.go

@@ -16,49 +16,40 @@
 package ashmem
 
 import (
-	"sync"
-
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
-	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/time"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
-	"gvisor.googlesource.com/gvisor/pkg/syserror"
 )
 
 // Device implements fs.InodeOperations.
 //
 // +stateify savable
 type Device struct {
-	fsutil.DeprecatedFileOperations  `state:"nosave"`
+	fsutil.InodeGenericChecker       `state:"nosave"`
 	fsutil.InodeNoExtendedAttributes `state:"nosave"`
+	fsutil.InodeNoopRelease          `state:"nosave"`
+	fsutil.InodeNoopTruncate         `state:"nosave"`
+	fsutil.InodeNoopWriteOut         `state:"nosave"`
 	fsutil.InodeNotDirectory         `state:"nosave"`
-	fsutil.InodeNotRenameable        `state:"nosave"`
+	fsutil.InodeNotMappable          `state:"nosave"`
 	fsutil.InodeNotSocket            `state:"nosave"`
 	fsutil.InodeNotSymlink           `state:"nosave"`
-	fsutil.NoFsync                   `state:"nosave"`
-	fsutil.NoMappable                `state:"nosave"`
-	fsutil.NoopWriteOut              `state:"nosave"`
-	fsutil.NotDirReaddir             `state:"nosave"`
+	fsutil.InodeVirtual              `state:"nosave"`
 
-	mu       sync.Mutex `state:"nosave"`
-	unstable fs.UnstableAttr
+	fsutil.InodeSimpleAttributes
 }
 
+var _ fs.InodeOperations = (*Device)(nil)
+
 // NewDevice creates and intializes a Device structure.
 func NewDevice(ctx context.Context, owner fs.FileOwner, fp fs.FilePermissions) *Device {
 	return &Device{
-		unstable: fs.WithCurrentTime(ctx, fs.UnstableAttr{
-			Owner: owner,
-			Perms: fp,
-			Links: 1,
-		}),
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fp, linux.ANON_INODE_FS_MAGIC),
 	}
 }
 
-// Release implements fs.InodeOperations.Release.
-func (ad *Device) Release(context.Context) {}
-
 // GetFile implements fs.InodeOperations.GetFile.
 func (ad *Device) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
 	return fs.NewFile(ctx, d, flags, &Area{
@@ -67,105 +58,3 @@ func (ad *Device) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags)
 		perms:     usermem.AnyAccess,
 	}), nil
 }
-
-// UnstableAttr implements fs.InodeOperations.UnstableAttr.
-func (ad *Device) UnstableAttr(ctx context.Context, inode *fs.Inode) (fs.UnstableAttr, error) {
-	ad.mu.Lock()
-	defer ad.mu.Unlock()
-	return ad.unstable, nil
-}
-
-// Check implements fs.InodeOperations.Check.
-func (ad *Device) Check(ctx context.Context, inode *fs.Inode, p fs.PermMask) bool {
-	return fs.ContextCanAccessFile(ctx, inode, p)
-}
-
-// SetPermissions implements fs.InodeOperations.SetPermissions.
-func (ad *Device) SetPermissions(ctx context.Context, inode *fs.Inode, fp fs.FilePermissions) bool {
-	ad.mu.Lock()
-	defer ad.mu.Unlock()
-	ad.unstable.Perms = fp
-	ad.unstable.StatusChangeTime = time.NowFromContext(ctx)
-	return true
-}
-
-// SetOwner implements fs.InodeOperations.SetOwner.
-func (ad *Device) SetOwner(ctx context.Context, inode *fs.Inode, owner fs.FileOwner) error {
-	ad.mu.Lock()
-	defer ad.mu.Unlock()
-	if owner.UID.Ok() {
-		ad.unstable.Owner.UID = owner.UID
-	}
-	if owner.GID.Ok() {
-		ad.unstable.Owner.GID = owner.GID
-	}
-	return nil
-}
-
-// SetTimestamps implements fs.InodeOperations.SetTimestamps.
-func (ad *Device) SetTimestamps(ctx context.Context, inode *fs.Inode, ts fs.TimeSpec) error {
-	if ts.ATimeOmit && ts.MTimeOmit {
-		return nil
-	}
-
-	ad.mu.Lock()
-	defer ad.mu.Unlock()
-
-	now := time.NowFromContext(ctx)
-	if !ts.ATimeOmit {
-		if ts.ATimeSetSystemTime {
-			ad.unstable.AccessTime = now
-		} else {
-			ad.unstable.AccessTime = ts.ATime
-		}
-	}
-	if !ts.MTimeOmit {
-		if ts.MTimeSetSystemTime {
-			ad.unstable.ModificationTime = now
-		} else {
-			ad.unstable.ModificationTime = ts.MTime
-		}
-	}
-	ad.unstable.StatusChangeTime = now
-	return nil
-}
-
-// Truncate implements fs.InodeOperations.WriteOut.
-//
-// Ignored by ashmem.
-func (ad *Device) Truncate(ctx context.Context, inode *fs.Inode, size int64) error {
-	return nil
-}
-
-// AddLink implements fs.InodeOperations.AddLink.
-//
-// Ashmem doesn't support links, no-op.
-func (ad *Device) AddLink() {}
-
-// DropLink implements fs.InodeOperations.DropLink.
-//
-// Ashmem doesn't support links, no-op.
-func (ad *Device) DropLink() {}
-
-// NotifyStatusChange implements fs.InodeOperations.NotifyStatusChange.
-func (ad *Device) NotifyStatusChange(ctx context.Context) {
-	ad.mu.Lock()
-	defer ad.mu.Unlock()
-	now := time.NowFromContext(ctx)
-	ad.unstable.ModificationTime = now
-	ad.unstable.StatusChangeTime = now
-}
-
-// IsVirtual implements fs.InodeOperations.IsVirtual.
-//
-// Ashmem is virtual.
-func (ad *Device) IsVirtual() bool {
-	return true
-}
-
-// StatFS implements fs.InodeOperations.StatFS.
-//
-// Ashmem doesn't support querying for filesystem info.
-func (ad *Device) StatFS(context.Context) (fs.Info, error) {
-	return fs.Info{}, syserror.ENOSYS
-}

pkg/sentry/fs/attr.go

@@ -180,6 +180,53 @@ type UnstableAttr struct {
 	Links uint64
 }
 
+// SetOwner sets the owner and group if they are valid.
+//
+// This method is NOT thread-safe. Callers must prevent concurrent calls.
+func (ua *UnstableAttr) SetOwner(ctx context.Context, owner FileOwner) {
+	if owner.UID.Ok() {
+		ua.Owner.UID = owner.UID
+	}
+	if owner.GID.Ok() {
+		ua.Owner.GID = owner.GID
+	}
+	ua.StatusChangeTime = ktime.NowFromContext(ctx)
+}
+
+// SetPermissions sets the permissions.
+//
+// This method is NOT thread-safe. Callers must prevent concurrent calls.
+func (ua *UnstableAttr) SetPermissions(ctx context.Context, p FilePermissions) {
+	ua.Perms = p
+	ua.StatusChangeTime = ktime.NowFromContext(ctx)
+}
+
+// SetTimestamps sets the timestamps according to the TimeSpec.
+//
+// This method is NOT thread-safe. Callers must prevent concurrent calls.
+func (ua *UnstableAttr) SetTimestamps(ctx context.Context, ts TimeSpec) {
+	if ts.ATimeOmit && ts.MTimeOmit {
+		return
+	}
+
+	now := ktime.NowFromContext(ctx)
+	if !ts.ATimeOmit {
+		if ts.ATimeSetSystemTime {
+			ua.AccessTime = now
+		} else {
+			ua.AccessTime = ts.ATime
+		}
+	}
+	if !ts.MTimeOmit {
+		if ts.MTimeSetSystemTime {
+			ua.ModificationTime = now
+		} else {
+			ua.ModificationTime = ts.MTime
+		}
+	}
+	ua.StatusChangeTime = now
+}
+
 // WithCurrentTime returns u with AccessTime == ModificationTime == current time.
 func WithCurrentTime(ctx context.Context, u UnstableAttr) UnstableAttr {
 	t := ktime.NowFromContext(ctx)

pkg/sentry/fs/binder/BUILD

@@ -16,11 +16,11 @@ go_library(
         "//pkg/sentry/fs",
         "//pkg/sentry/fs/fsutil",
         "//pkg/sentry/kernel",
-        "//pkg/sentry/kernel/time",
         "//pkg/sentry/memmap",
         "//pkg/sentry/platform",
         "//pkg/sentry/usage",
         "//pkg/sentry/usermem",
         "//pkg/syserror",
+        "//pkg/waiter",
     ],
 )

pkg/sentry/fs/binder/binder.go

@@ -24,12 +24,12 @@ import (
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
-	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/time"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/memmap"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/platform"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usage"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
 	"gvisor.googlesource.com/gvisor/pkg/syserror"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
 )
 
 const (
@@ -43,34 +43,29 @@ const (
 //
 // +stateify savable
 type Device struct {
+	fsutil.InodeGenericChecker       `state:"nosave"`
 	fsutil.InodeNoExtendedAttributes `state:"nosave"`
+	fsutil.InodeNoopRelease          `state:"nosave"`
+	fsutil.InodeNoopTruncate         `state:"nosave"`
+	fsutil.InodeNoopWriteOut         `state:"nosave"`
 	fsutil.InodeNotDirectory         `state:"nosave"`
-	fsutil.InodeNotRenameable        `state:"nosave"`
+	fsutil.InodeNotMappable          `state:"nosave"`
 	fsutil.InodeNotSocket            `state:"nosave"`
 	fsutil.InodeNotSymlink           `state:"nosave"`
-	fsutil.NoMappable                `state:"nosave"`
-	fsutil.NoopWriteOut              `state:"nosave"`
-	fsutil.DeprecatedFileOperations  `state:"nosave"`
+	fsutil.InodeVirtual              `state:"nosave"`
 
-	// mu protects unstable.
-	mu       sync.Mutex `state:"nosave"`
-	unstable fs.UnstableAttr
+	fsutil.InodeSimpleAttributes
 }
 
+var _ fs.InodeOperations = (*Device)(nil)
+
 // NewDevice creates and intializes a Device structure.
 func NewDevice(ctx context.Context, owner fs.FileOwner, fp fs.FilePermissions) *Device {
 	return &Device{
-		unstable: fs.WithCurrentTime(ctx, fs.UnstableAttr{
-			Owner: owner,
-			Perms: fp,
-			Links: 1,
-		}),
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fp, 0),
 	}
 }
 
-// Release implements fs.InodeOperations.Release.
-func (bd *Device) Release(context.Context) {}
-
 // GetFile implements fs.InodeOperations.GetFile.
 //
 // TODO: Add functionality to GetFile: Additional fields will be
@@ -85,115 +80,13 @@ func (bd *Device) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags)
 	}), nil
 }
 
-// UnstableAttr implements fs.InodeOperations.UnstableAttr.
-func (bd *Device) UnstableAttr(ctx context.Context, inode *fs.Inode) (fs.UnstableAttr, error) {
-	bd.mu.Lock()
-	defer bd.mu.Unlock()
-	return bd.unstable, nil
-}
-
-// Check implements fs.InodeOperations.Check.
-func (bd *Device) Check(ctx context.Context, inode *fs.Inode, p fs.PermMask) bool {
-	return fs.ContextCanAccessFile(ctx, inode, p)
-}
-
-// SetPermissions implements fs.InodeOperations.SetPermissions.
-func (bd *Device) SetPermissions(ctx context.Context, inode *fs.Inode, fp fs.FilePermissions) bool {
-	bd.mu.Lock()
-	defer bd.mu.Unlock()
-	bd.unstable.Perms = fp
-	bd.unstable.StatusChangeTime = time.NowFromContext(ctx)
-	return true
-}
-
-// SetOwner implements fs.InodeOperations.SetOwner.
-func (bd *Device) SetOwner(ctx context.Context, inode *fs.Inode, owner fs.FileOwner) error {
-	bd.mu.Lock()
-	defer bd.mu.Unlock()
-	if owner.UID.Ok() {
-		bd.unstable.Owner.UID = owner.UID
-	}
-	if owner.GID.Ok() {
-		bd.unstable.Owner.GID = owner.GID
-	}
-	return nil
-}
-
-// SetTimestamps implements fs.InodeOperations.SetTimestamps.
-func (bd *Device) SetTimestamps(ctx context.Context, inode *fs.Inode, ts fs.TimeSpec) error {
-	if ts.ATimeOmit && ts.MTimeOmit {
-		return nil
-	}
-
-	bd.mu.Lock()
-	defer bd.mu.Unlock()
-
-	now := time.NowFromContext(ctx)
-	if !ts.ATimeOmit {
-		if ts.ATimeSetSystemTime {
-			bd.unstable.AccessTime = now
-		} else {
-			bd.unstable.AccessTime = ts.ATime
-		}
-	}
-	if !ts.MTimeOmit {
-		if ts.MTimeSetSystemTime {
-			bd.unstable.ModificationTime = now
-		} else {
-			bd.unstable.ModificationTime = ts.MTime
-		}
-	}
-	bd.unstable.StatusChangeTime = now
-	return nil
-}
-
-// Truncate implements fs.InodeOperations.WriteOut.
-//
-// Ignored for a character device, such as Binder.
-func (bd *Device) Truncate(ctx context.Context, inode *fs.Inode, size int64) error {
-	return nil
-}
-
-// AddLink implements fs.InodeOperations.AddLink.
-//
-// Binder doesn't support links, no-op.
-func (bd *Device) AddLink() {}
-
-// DropLink implements fs.InodeOperations.DropLink.
-//
-// Binder doesn't support links, no-op.
-func (bd *Device) DropLink() {}
-
-// NotifyStatusChange implements fs.InodeOperations.NotifyStatusChange.
-func (bd *Device) NotifyStatusChange(ctx context.Context) {
-	bd.mu.Lock()
-	defer bd.mu.Unlock()
-	now := time.NowFromContext(ctx)
-	bd.unstable.ModificationTime = now
-	bd.unstable.StatusChangeTime = now
-}
-
-// IsVirtual implements fs.InodeOperations.IsVirtual.
-//
-// Binder is virtual.
-func (bd *Device) IsVirtual() bool {
-	return true
-}
-
-// StatFS implements fs.InodeOperations.StatFS.
-//
-// Binder doesn't support querying for filesystem info.
-func (bd *Device) StatFS(context.Context) (fs.Info, error) {
-	return fs.Info{}, syserror.ENOSYS
-}
-
 // Proc implements fs.FileOperations and fs.IoctlGetter.
 //
 // +stateify savable
 type Proc struct {
-	fsutil.NoFsync                  `state:"nosave"`
-	fsutil.DeprecatedFileOperations `state:"nosave"`
-	fsutil.NotDirReaddir            `state:"nosave"`
+	waiter.AlwaysReady       `state:"nosave"`
+	fsutil.FileNoFsync       `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
 
 	bd       *Device
 	task     *kernel.Task

pkg/sentry/fs/dev/BUILD

@@ -32,5 +32,6 @@ go_library(
         "//pkg/sentry/safemem",
         "//pkg/sentry/usermem",
         "//pkg/syserror",
+        "//pkg/waiter",
     ],
 )

pkg/sentry/fs/dev/dev.go

@@ -16,6 +16,8 @@
 package dev
 
 import (
+	"math"
+
 	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ashmem"
@@ -26,13 +28,6 @@ import (
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
 )
 
-// Dev is the root node.
-//
-// +stateify savable
-type Dev struct {
-	ramfs.Dir
-}
-
 func newCharacterDevice(iops fs.InodeOperations, msrc *fs.MountSource) *fs.Inode {
 	return fs.NewInode(iops, msrc, fs.StableAttr{
 		DeviceID:  devDevice.DeviceID(),
@@ -43,8 +38,7 @@ func newCharacterDevice(iops fs.InodeOperations, msrc *fs.MountSource) *fs.Inode
 }
 
 func newDirectory(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
-	iops := &ramfs.Dir{}
-	iops.InitDir(ctx, map[string]*fs.Inode{}, fs.RootOwner, fs.FilePermsFromMode(0555))
+	iops := ramfs.NewDir(ctx, nil, fs.RootOwner, fs.FilePermsFromMode(0555))
 	return fs.NewInode(iops, msrc, fs.StableAttr{
 		DeviceID:  devDevice.DeviceID(),
 		InodeID:   devDevice.NextIno(),
@@ -54,8 +48,7 @@ func newDirectory(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
 }
 
 func newSymlink(ctx context.Context, target string, msrc *fs.MountSource) *fs.Inode {
-	iops := &ramfs.Symlink{}
-	iops.InitSymlink(ctx, fs.RootOwner, target)
+	iops := ramfs.NewSymlink(ctx, fs.RootOwner, target)
 	return fs.NewInode(iops, msrc, fs.StableAttr{
 		DeviceID:  devDevice.DeviceID(),
 		InodeID:   devDevice.NextIno(),
@@ -66,8 +59,6 @@ func newSymlink(ctx context.Context, target string, msrc *fs.MountSource) *fs.In
 
 // New returns the root node of a device filesystem.
 func New(ctx context.Context, msrc *fs.MountSource, binderEnabled bool, ashmemEnabled bool) *fs.Inode {
-	d := &Dev{}
-
 	contents := map[string]*fs.Inode{
 		"fd":     newSymlink(ctx, "/proc/self/fd", msrc),
 		"stdin":  newSymlink(ctx, "/proc/self/fd/0", msrc),
@@ -114,11 +105,19 @@ func New(ctx context.Context, msrc *fs.MountSource, binderEnabled bool, ashmemEn
 		contents["ashmem"] = newCharacterDevice(ashmem, msrc)
 	}
 
-	d.InitDir(ctx, contents, fs.RootOwner, fs.FilePermsFromMode(0555))
-	return fs.NewInode(d, msrc, fs.StableAttr{
+	iops := ramfs.NewDir(ctx, contents, fs.RootOwner, fs.FilePermsFromMode(0555))
+	return fs.NewInode(iops, msrc, fs.StableAttr{
 		DeviceID:  devDevice.DeviceID(),
 		InodeID:   devDevice.NextIno(),
 		BlockSize: usermem.PageSize,
 		Type:      fs.Directory,
 	})
 }
+
+// readZeros implements fs.FileOperations.Read with infinite null bytes.
+type readZeros struct{}
+
+// Read implements fs.FileOperations.Read.
+func (readZeros) Read(ctx context.Context, file *fs.File, dst usermem.IOSequence, offset int64) (int64, error) {
+	return dst.ZeroOut(ctx, math.MaxInt64)
+}

pkg/sentry/fs/dev/fs.go

@@ -33,6 +33,8 @@ const ashmemEnabledKey = "ashmem_enabled"
 // +stateify savable
 type filesystem struct{}
 
+var _ fs.Filesystem = (*filesystem)(nil)
+
 func init() {
 	fs.RegisterFilesystem(&filesystem{})
 }

pkg/sentry/fs/dev/full.go

@@ -15,41 +15,64 @@
 package dev
 
 import (
-	"math"
-
 	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
-	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
 	"gvisor.googlesource.com/gvisor/pkg/syserror"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
 )
 
 // fullDevice is used to implement /dev/full.
 //
 // +stateify savable
 type fullDevice struct {
-	ramfs.Entry
+	fsutil.InodeGenericChecker       `state:"nosave"`
+	fsutil.InodeNoExtendedAttributes `state:"nosave"`
+	fsutil.InodeNoopRelease          `state:"nosave"`
+	fsutil.InodeNoopTruncate         `state:"nosave"`
+	fsutil.InodeNoopWriteOut         `state:"nosave"`
+	fsutil.InodeNotDirectory         `state:"nosave"`
+	fsutil.InodeNotMappable          `state:"nosave"`
+	fsutil.InodeNotSocket            `state:"nosave"`
+	fsutil.InodeNotSymlink           `state:"nosave"`
+	fsutil.InodeVirtual              `state:"nosave"`
+
+	fsutil.InodeSimpleAttributes
 }
 
+var _ fs.InodeOperations = (*fullDevice)(nil)
+
 func newFullDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMode) *fullDevice {
-	f := &fullDevice{}
-	f.InitEntry(ctx, owner, fs.FilePermsFromMode(mode))
+	f := &fullDevice{
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(mode), linux.TMPFS_MAGIC),
+	}
 	return f
 }
 
-// DeprecatedPwritev implements fs.InodeOperations.DeprecatedPwritev by
-// returining ENOSPC.
-func (f *fullDevice) DeprecatedPwritev(_ context.Context, _ usermem.IOSequence, _ int64) (int64, error) {
+// GetFile implements fs.InodeOperations.GetFile.
+func (f *fullDevice) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	flags.Pread = true
+	return fs.NewFile(ctx, dirent, flags, &fullFileOperations{}), nil
+}
+
+// +stateify savable
+type fullFileOperations struct {
+	waiter.AlwaysReady       `state:"nosave"`
+	fsutil.FileGenericSeek   `state:"nosave"`
+	fsutil.FileNoIoctl       `state:"nosave"`
+	fsutil.FileNoMMap        `state:"nosave"`
+	fsutil.FileNoopFlush     `state:"nosave"`
+	fsutil.FileNoopFsync     `state:"nosave"`
+	fsutil.FileNoopRelease   `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
+	readZeros                `state:"nosave"`
+}
+
+var _ fs.FileOperations = (*fullFileOperations)(nil)
+
+// Write implements FileOperations.Write.
+func (fullFileOperations) Write(context.Context, *fs.File, usermem.IOSequence, int64) (int64, error) {
 	return 0, syserror.ENOSPC
 }
-
-// DeprecatedPreadv implements fs.InodeOperations.DeprecatedPreadv.
-func (f *fullDevice) DeprecatedPreadv(ctx context.Context, dst usermem.IOSequence, _ int64) (int64, error) {
-	return dst.ZeroOut(ctx, math.MaxInt64)
-}
-
-// Truncate should be simply ignored for character devices on linux.
-func (f *fullDevice) Truncate(context.Context, *fs.Inode, int64) error {
-	return nil
-}

pkg/sentry/fs/dev/null.go

@@ -15,78 +15,104 @@
 package dev
 
 import (
-	"io"
-	"math"
-
 	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
-	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/memmap"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/mm"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/platform"
-	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
 )
 
 // +stateify savable
 type nullDevice struct {
-	ramfs.Entry
+	fsutil.InodeGenericChecker       `state:"nosave"`
+	fsutil.InodeNoExtendedAttributes `state:"nosave"`
+	fsutil.InodeNoopRelease          `state:"nosave"`
+	fsutil.InodeNoopTruncate         `state:"nosave"`
+	fsutil.InodeNoopWriteOut         `state:"nosave"`
+	fsutil.InodeNotDirectory         `state:"nosave"`
+	fsutil.InodeNotMappable          `state:"nosave"`
+	fsutil.InodeNotSocket            `state:"nosave"`
+	fsutil.InodeNotSymlink           `state:"nosave"`
+	fsutil.InodeVirtual              `state:"nosave"`
+
+	fsutil.InodeSimpleAttributes
 }
 
+var _ fs.InodeOperations = (*nullDevice)(nil)
+
 func newNullDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMode) *nullDevice {
-	n := &nullDevice{}
-	n.InitEntry(ctx, owner, fs.FilePermsFromMode(mode))
+	n := &nullDevice{
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(mode), linux.TMPFS_MAGIC),
+	}
 	return n
 }
 
-// DeprecatedPreadv reads data from the device.
-func (n *nullDevice) DeprecatedPreadv(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
-	return 0, io.EOF
+// GetFile implements fs.FileOperations.GetFile.
+func (n *nullDevice) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	flags.Pread = true
+	flags.Pwrite = true
+
+	return fs.NewFile(ctx, dirent, flags, &nullFileOperations{}), nil
 }
 
-// DeprecatedPwritev discards writes.
-func (n *nullDevice) DeprecatedPwritev(_ context.Context, src usermem.IOSequence, offset int64) (int64, error) {
-	return src.NumBytes(), nil
+// +stateify savable
+type nullFileOperations struct {
+	waiter.AlwaysReady       `state:"nosave"`
+	fsutil.FileGenericSeek   `state:"nosave"`
+	fsutil.FileNoIoctl       `state:"nosave"`
+	fsutil.FileNoMMap        `state:"nosave"`
+	fsutil.FileNoopFlush     `state:"nosave"`
+	fsutil.FileNoopFsync     `state:"nosave"`
+	fsutil.FileNoopRead      `state:"nosave"`
+	fsutil.FileNoopWrite     `state:"nosave"`
+	fsutil.FileNoopRelease   `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
 }
 
-// Truncate should be simply ignored for character devices on linux.
-func (n *nullDevice) Truncate(context.Context, *fs.Inode, int64) error {
-	return nil
-}
+var _ fs.FileOperations = (*nullFileOperations)(nil)
 
 // +stateify savable
 type zeroDevice struct {
 	nullDevice
 }
 
+var _ fs.InodeOperations = (*zeroDevice)(nil)
+
 func newZeroDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMode) *zeroDevice {
-	zd := &zeroDevice{}
-	zd.InitEntry(ctx, owner, fs.FilePermsFromMode(mode))
+	zd := &zeroDevice{
+		nullDevice: nullDevice{
+			InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(mode), linux.TMPFS_MAGIC),
+		},
+	}
 	return zd
 }
 
-// DeprecatedPreadv implements fs.InodeOperations.DeprecatedPreadv.
-func (zd *zeroDevice) DeprecatedPreadv(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
-	return dst.ZeroOut(ctx, math.MaxInt64)
-}
-
-// GetFile overrides ramfs.Entry.GetFile and returns a zeroFile instead.
+// GetFile implements fs.FileOperations.GetFile.
 func (zd *zeroDevice) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
-	// Allow pread(2) and pwrite(2) on this file.
 	flags.Pread = true
 	flags.Pwrite = true
 
-	return fs.NewFile(ctx, dirent, flags, &zeroFileOperations{
-		FileOperations: &fsutil.Handle{HandleOperations: dirent.Inode.HandleOps()},
-	}), nil
+	return fs.NewFile(ctx, dirent, flags, &zeroFileOperations{}), nil
 }
 
 // +stateify savable
 type zeroFileOperations struct {
-	fs.FileOperations
+	waiter.AlwaysReady       `state:"nosave"`
+	fsutil.FileGenericSeek   `state:"nosave"`
+	fsutil.FileNoopFlush     `state:"nosave"`
+	fsutil.FileNoopFsync     `state:"nosave"`
+	fsutil.FileNoopRelease   `state:"nosave"`
+	fsutil.FileNoopWrite     `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
+	fsutil.FileNoIoctl       `state:"nosave"`
+	readZeros                `state:"nosave"`
 }
 
+var _ fs.FileOperations = (*zeroFileOperations)(nil)
+
 // ConfigureMMap implements fs.FileOperations.ConfigureMMap.
 func (*zeroFileOperations) ConfigureMMap(ctx context.Context, file *fs.File, opts *memmap.MMapOpts) error {
 	m, err := mm.NewSharedAnonMappable(opts.Length, platform.FromContext(ctx))

pkg/sentry/fs/dev/random.go

@@ -19,37 +19,58 @@ import (
 	"gvisor.googlesource.com/gvisor/pkg/rand"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
-	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/safemem"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
 )
 
 // +stateify savable
 type randomDevice struct {
-	ramfs.Entry
+	fsutil.InodeGenericChecker       `state:"nosave"`
+	fsutil.InodeNoExtendedAttributes `state:"nosave"`
+	fsutil.InodeNoopRelease          `state:"nosave"`
+	fsutil.InodeNoopTruncate         `state:"nosave"`
+	fsutil.InodeNoopWriteOut         `state:"nosave"`
+	fsutil.InodeNotDirectory         `state:"nosave"`
+	fsutil.InodeNotMappable          `state:"nosave"`
+	fsutil.InodeNotSocket            `state:"nosave"`
+	fsutil.InodeNotSymlink           `state:"nosave"`
+	fsutil.InodeVirtual              `state:"nosave"`
+
+	fsutil.InodeSimpleAttributes
 }
 
+var _ fs.InodeOperations = (*randomDevice)(nil)
+
 func newRandomDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMode) *randomDevice {
-	r := &randomDevice{}
-	r.InitEntry(ctx, owner, fs.FilePermsFromMode(mode))
+	r := &randomDevice{
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(mode), linux.TMPFS_MAGIC),
+	}
 	return r
 }
 
-// DeprecatedPreadv reads random data.
-func (*randomDevice) DeprecatedPreadv(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
+// GetFile implements fs.InodeOperations.GetFile.
+func (randomDevice) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	return fs.NewFile(ctx, dirent, flags, &randomFileOperations{}), nil
+}
+
+// +stateify savable
+type randomFileOperations struct {
+	waiter.AlwaysReady       `state:"nosave"`
+	fsutil.FileGenericSeek   `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
+	fsutil.FileNoMMap        `state:"nosave"`
+	fsutil.FileNoopFsync     `state:"nosave"`
+	fsutil.FileNoopFlush     `state:"nosave"`
+	fsutil.FileNoIoctl       `state:"nosave"`
+	fsutil.FileNoopRelease   `state:"nosave"`
+	fsutil.FileNoopWrite     `state:"nosave"`
+}
+
+var _ fs.FileOperations = (*randomFileOperations)(nil)
+
+// Read implements fs.FileOperations.Read.
+func (randomFileOperations) Read(ctx context.Context, _ *fs.File, dst usermem.IOSequence, _ int64) (int64, error) {
 	return dst.CopyOutFrom(ctx, safemem.FromIOReader{rand.Reader})
 }
-
-// DeprecatedPwritev implements fs.HandleOperations.DeprecatedPwritev.
-func (*randomDevice) DeprecatedPwritev(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
-	// On Linux, "Writing to /dev/random or /dev/urandom will update the
-	// entropy pool with the data written, but this will not result in a higher
-	// entropy count" - random(4). We don't need to support this, but we do
-	// need to support the write, so just make it a no-op a la /dev/null.
-	return src.NumBytes(), nil
-}
-
-// Truncate should be simply ignored for character devices on linux.
-func (r *randomDevice) Truncate(context.Context, *fs.Inode, int64) error {
-	return nil
-}

pkg/sentry/fs/dirent.go

@@ -837,8 +837,8 @@ func (d *Dirent) CreateFifo(ctx context.Context, root *Dirent, name string, perm
 	})
 }
 
-// getDotAttrs returns the DentAttrs corresponding to "." and ".." directories.
-func (d *Dirent) getDotAttrs(root *Dirent) (DentAttr, DentAttr) {
+// GetDotAttrs returns the DentAttrs corresponding to "." and ".." directories.
+func (d *Dirent) GetDotAttrs(root *Dirent) (DentAttr, DentAttr) {
 	// Get '.'.
 	sattr := d.Inode.StableAttr
 	dot := DentAttr{
@@ -870,7 +870,7 @@ func (d *Dirent) readdirFrozen(root *Dirent, offset int64, dirCtx *DirCtx) (int6
 	// Collect attrs for "." and  "..".
 	attrs := make(map[string]DentAttr)
 	names := []string{".", ".."}
-	attrs["."], attrs[".."] = d.getDotAttrs(root)
+	attrs["."], attrs[".."] = d.GetDotAttrs(root)
 
 	// Get info from all children.
 	d.mu.Lock()
@@ -965,7 +965,7 @@ func direntReaddir(ctx context.Context, d *Dirent, it DirIterator, root *Dirent,
 	}
 
 	// Collect attrs for "." and "..".
-	dot, dotdot := d.getDotAttrs(root)
+	dot, dotdot := d.GetDotAttrs(root)
 
 	// Emit "." and ".." if the offset is low enough.
 	if offset == 0 {

pkg/sentry/fs/fdpipe/pipe.go

@@ -37,13 +37,13 @@ import (
 //
 // +stateify savable
 type pipeOperations struct {
-	fsutil.PipeSeek      `state:"nosave"`
-	fsutil.NotDirReaddir `state:"nosave"`
-	fsutil.NoFsync       `state:"nosave"`
-	fsutil.NoopFlush     `state:"nosave"`
-	fsutil.NoMMap        `state:"nosave"`
-	fsutil.NoIoctl       `state:"nosave"`
-	waiter.Queue         `state:"nosave"`
+	fsutil.FilePipeSeek      `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
+	fsutil.FileNoFsync       `state:"nosave"`
+	fsutil.FileNoopFlush     `state:"nosave"`
+	fsutil.FileNoMMap        `state:"nosave"`
+	fsutil.FileNoIoctl       `state:"nosave"`
+	waiter.Queue             `state:"nosave"`
 
 	// flags are the flags used to open the pipe.
 	flags fs.FileFlags `state:".(fs.FileFlags)"`

pkg/sentry/fs/file_operations.go

@@ -91,7 +91,7 @@ type FileOperations interface {
 	Flush(ctx context.Context, file *File) error
 
 	// ConfigureMMap mutates opts to implement mmap(2) for the file. Most
-	// implementations can either embed fsutil.NoMMap (if they don't support
+	// implementations can either embed fsutil.FileNoMMap (if they don't support
 	// memory mapping) or call fsutil.GenericConfigureMMap with the appropriate
 	// memmap.Mappable.
 	ConfigureMMap(ctx context.Context, file *File, opts *memmap.MMapOpts) error

pkg/sentry/fs/file_overlay_test.go

@@ -20,7 +20,8 @@ import (
 
 	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
-	ramfstest "gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs/test"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/contexttest"
 )
 
@@ -135,7 +136,7 @@ func TestReaddirRevalidation(t *testing.T) {
 
 	// Get a handle to the dirent in the upper filesystem so that we can
 	// modify it without going through the dirent.
-	upperDir := upper.InodeOperations.(*dir).InodeOperations.(*ramfstest.Dir)
+	upperDir := upper.InodeOperations.(*dir).InodeOperations.(*ramfs.Dir)
 
 	// Check that overlay returns the files from both upper and lower.
 	openDir, err := overlay.GetFile(ctx, fs.NewDirent(overlay, "stub"), fs.FileFlags{Read: true})
@@ -155,7 +156,7 @@ func TestReaddirRevalidation(t *testing.T) {
 	if err := upperDir.Remove(ctx, upper, "a"); err != nil {
 		t.Fatalf("error removing child: %v", err)
 	}
-	upperDir.AddChild(ctx, "c", fs.NewInode(ramfstest.NewFile(ctx, fs.FilePermissions{}),
+	upperDir.AddChild(ctx, "c", fs.NewInode(fsutil.NewSimpleFileInode(ctx, fs.RootOwner, fs.FilePermissions{}, 0),
 		upper.MountSource, fs.StableAttr{Type: fs.RegularFile}))
 
 	// Seek to beginning of the directory and do the readdir again.

pkg/sentry/fs/filetest/filetest.go

@@ -31,14 +31,14 @@ import (
 // TestFileOperations is an implementation of the File interface. It provides all
 // required methods.
 type TestFileOperations struct {
-	fsutil.NoopRelease   `state:"nosave"`
-	fsutil.PipeSeek      `state:"nosave"`
-	fsutil.NotDirReaddir `state:"nosave"`
-	fsutil.NoFsync       `state:"nosave"`
-	fsutil.NoopFlush     `state:"nosave"`
-	fsutil.NoMMap        `state:"nosave"`
-	fsutil.NoIoctl       `state:"nosave"`
-	waiter.AlwaysReady   `state:"nosave"`
+	fsutil.FileNoopRelease   `state:"nosave"`
+	fsutil.FilePipeSeek      `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
+	fsutil.FileNoFsync       `state:"nosave"`
+	fsutil.FileNoopFlush     `state:"nosave"`
+	fsutil.FileNoMMap        `state:"nosave"`
+	fsutil.FileNoIoctl       `state:"nosave"`
+	waiter.AlwaysReady       `state:"nosave"`
 }
 
 // NewTestFile creates and initializes a new test file.