Implement POSIX locks

- Change FileDescriptionImpl Lock/UnlockPOSIX signature to
  take {start,length,whence}, so the correct offset can be
  calculated in the implementations.
- Create PosixLocker interface to make it possible to share
  the same locking code from different implementations.

Closes #1480

PiperOrigin-RevId: 316910286

4 files changed, 26 insertions, 7 deletions

diff --git a/pkg/sentry/fsimpl/devpts/BUILD b/pkg/sentry/fsimpl/devpts/BUILD
index cf440dce8..93512c9b6 100644
--- a/pkg/sentry/fsimpl/devpts/BUILD
+++ b/pkg/sentry/fsimpl/devpts/BUILD
@@ -18,12 +18,12 @@ go_library(
         "//pkg/context",
         "//pkg/safemem",
         "//pkg/sentry/arch",
+        "//pkg/sentry/fs/lock",
         "//pkg/sentry/fsimpl/kernfs",
         "//pkg/sentry/kernel",
         "//pkg/sentry/kernel/auth",
         "//pkg/sentry/unimpl",
         "//pkg/sentry/vfs",
-        "//pkg/sentry/vfs/lock",
         "//pkg/sync",
         "//pkg/syserror",
         "//pkg/usermem",
diff --git a/pkg/sentry/fsimpl/devpts/devpts.go b/pkg/sentry/fsimpl/devpts/devpts.go
index 9b0e0cca2..e6fda2b4f 100644
--- a/pkg/sentry/fsimpl/devpts/devpts.go
+++ b/pkg/sentry/fsimpl/devpts/devpts.go
@@ -28,7 +28,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/sentry/vfs/lock"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
 
@@ -117,7 +116,7 @@ type rootInode struct {
 	kernfs.InodeNotSymlink
 	kernfs.OrderedChildren
 
-	locks lock.FileLocks
+	locks vfs.FileLocks
 
 	// Keep a reference to this inode's dentry.
 	dentry kernfs.Dentry
diff --git a/pkg/sentry/fsimpl/devpts/master.go b/pkg/sentry/fsimpl/devpts/master.go
index 1d22adbe3..69879498a 100644
--- a/pkg/sentry/fsimpl/devpts/master.go
+++ b/pkg/sentry/fsimpl/devpts/master.go
@@ -18,11 +18,11 @@ import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
+	fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/unimpl"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/sentry/vfs/lock"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
@@ -35,7 +35,7 @@ type masterInode struct {
 	kernfs.InodeNotDirectory
 	kernfs.InodeNotSymlink
 
-	locks lock.FileLocks
+	locks vfs.FileLocks
 
 	// Keep a reference to this inode's dentry.
 	dentry kernfs.Dentry
@@ -189,6 +189,16 @@ func (mfd *masterFileDescription) Stat(ctx context.Context, opts vfs.StatOptions
 	return mfd.inode.Stat(fs, opts)
 }
 
+// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
+func (mfd *masterFileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
+	return mfd.Locks().LockPOSIX(ctx, &mfd.vfsfd, uid, t, start, length, whence, block)
+}
+
+// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
+func (mfd *masterFileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error {
+	return mfd.Locks().UnlockPOSIX(ctx, &mfd.vfsfd, uid, start, length, whence)
+}
+
 // maybeEmitUnimplementedEvent emits unimplemented event if cmd is valid.
 func maybeEmitUnimplementedEvent(ctx context.Context, cmd uint32) {
 	switch cmd {
diff --git a/pkg/sentry/fsimpl/devpts/slave.go b/pkg/sentry/fsimpl/devpts/slave.go
index 7fe475080..cf1a0f0ac 100644
--- a/pkg/sentry/fsimpl/devpts/slave.go
+++ b/pkg/sentry/fsimpl/devpts/slave.go
@@ -18,10 +18,10 @@ import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
+	fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/sentry/vfs/lock"
 	"gvisor.dev/gvisor/pkg/syserror"
 	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
@@ -34,7 +34,7 @@ type slaveInode struct {
 	kernfs.InodeNotDirectory
 	kernfs.InodeNotSymlink
 
-	locks lock.FileLocks
+	locks vfs.FileLocks
 
 	// Keep a reference to this inode's dentry.
 	dentry kernfs.Dentry
@@ -185,3 +185,13 @@ func (sfd *slaveFileDescription) Stat(ctx context.Context, opts vfs.StatOptions)
 	fs := sfd.vfsfd.VirtualDentry().Mount().Filesystem()
 	return sfd.inode.Stat(fs, opts)
 }
+
+// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
+func (sfd *slaveFileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
+	return sfd.Locks().LockPOSIX(ctx, &sfd.vfsfd, uid, t, start, length, whence, block)
+}
+
+// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
+func (sfd *slaveFileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error {
+	return sfd.Locks().UnlockPOSIX(ctx, &sfd.vfsfd, uid, start, length, whence)
+}