Implement flock(2) in VFS2

LockFD is the generic implementation that can be embedded in
FileDescriptionImpl implementations. Unique lock ID is
maintained in vfs.FileDescription and is created on demand.

Updates #1480

PiperOrigin-RevId: 315604825

2 files changed, 6 insertions, 2 deletions

diff --git a/pkg/sentry/fsimpl/sys/BUILD b/pkg/sentry/fsimpl/sys/BUILD
index a741e2bb6..237f17def 100644
--- a/pkg/sentry/fsimpl/sys/BUILD
+++ b/pkg/sentry/fsimpl/sys/BUILD
@@ -15,6 +15,7 @@ go_library(
         "//pkg/sentry/kernel",
         "//pkg/sentry/kernel/auth",
         "//pkg/sentry/vfs",
+        "//pkg/sentry/vfs/lock",
         "//pkg/syserror",
     ],
 )
diff --git a/pkg/sentry/fsimpl/sys/sys.go b/pkg/sentry/fsimpl/sys/sys.go
index 0af373604..b84463d3a 100644
--- a/pkg/sentry/fsimpl/sys/sys.go
+++ b/pkg/sentry/fsimpl/sys/sys.go
@@ -25,6 +25,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"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"
 )
 
@@ -98,8 +99,10 @@ type dir struct {
 	kernfs.InodeNoDynamicLookup
 	kernfs.InodeNotSymlink
 	kernfs.InodeDirectoryNoNewChildren
-
 	kernfs.OrderedChildren
+
+	locks lock.FileLocks
+
 	dentry kernfs.Dentry
 }
 
@@ -121,7 +124,7 @@ func (*dir) SetStat(context.Context, *vfs.Filesystem, *auth.Credentials, vfs.Set
 
 // Open implements kernfs.Inode.Open.
 func (d *dir) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
-	fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &opts)
+	fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &d.locks, &opts)
 	if err != nil {
 		return nil, err
 	}