Use new reference count utility throughout gvisor.

This uses the refs_vfs2 template in vfs2 as well as objects common to vfs1 and
vfs2. Note that vfs1-only refcounts are not replaced, since vfs1 will be deleted
soon anyway.

The following structs now use the new tool, with leak check enabled:
devpts:rootInode
fuse:inode
kernfs:Dentry
kernfs:dir
kernfs:readonlyDir
kernfs:StaticDirectory
proc:fdDirInode
proc:fdInfoDirInode
proc:subtasksInode
proc:taskInode
proc:tasksInode
vfs:FileDescription
vfs:MountNamespace
vfs:Filesystem
sys:dir
kernel:FSContext
kernel:ProcessGroup
kernel:Session
shm:Shm
mm:aioMappable
mm:SpecialMappable
transport:queue

And the following use the template, but because they currently are not leak
checked, a TODO is left instead of enabling leak check in this patch:
kernel:FDTable
tun:tunEndpoint

Updates #1486.

PiperOrigin-RevId: 328460377

1 files changed, 7 insertions, 0 deletions

diff --git a/pkg/sentry/fsimpl/proc/subtasks.go b/pkg/sentry/fsimpl/proc/subtasks.go
index f25747da3..01c0efb3a 100644
--- a/pkg/sentry/fsimpl/proc/subtasks.go
+++ b/pkg/sentry/fsimpl/proc/subtasks.go
@@ -31,6 +31,7 @@ import (
 //
 // +stateify savable
 type subtasksInode struct {
+	subtasksInodeRefs
 	kernfs.InodeNotSymlink
 	kernfs.InodeDirectoryNoNewChildren
 	kernfs.InodeAttrs
@@ -57,6 +58,7 @@ func (fs *filesystem) newSubtasks(task *kernel.Task, pidns *kernel.PIDNamespace,
 	// Note: credentials are overridden by taskOwnedInode.
 	subInode.InodeAttrs.Init(task.Credentials(), linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), linux.ModeDirectory|0555)
 	subInode.OrderedChildren.Init(kernfs.OrderedChildrenOptions{})
+	subInode.EnableLeakCheck()
 
 	inode := &taskOwnedInode{Inode: subInode, owner: task}
 	dentry := &kernfs.Dentry{}
@@ -182,3 +184,8 @@ func (i *subtasksInode) Stat(ctx context.Context, vsfs *vfs.Filesystem, opts vfs
 func (*subtasksInode) SetStat(context.Context, *vfs.Filesystem, *auth.Credentials, vfs.SetStatOptions) error {
 	return syserror.EPERM
 }
+
+// DecRef implements kernfs.Inode.
+func (i *subtasksInode) DecRef(context.Context) {
+	i.subtasksInodeRefs.DecRef(i.Destroy)
+}