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

2 files changed, 20 insertions, 0 deletions

diff --git a/pkg/sentry/fsimpl/fuse/BUILD b/pkg/sentry/fsimpl/fuse/BUILD
index 999111deb..53a4f3012 100644
--- a/pkg/sentry/fsimpl/fuse/BUILD
+++ b/pkg/sentry/fsimpl/fuse/BUILD
@@ -15,6 +15,17 @@ go_template_instance(
     },
 )
 
+go_template_instance(
+    name = "inode_refs",
+    out = "inode_refs.go",
+    package = "fuse",
+    prefix = "inode",
+    template = "//pkg/refs_vfs2:refs_template",
+    types = {
+        "T": "inode",
+    },
+)
+
 go_library(
     name = "fuse",
     srcs = [
@@ -22,6 +33,7 @@ go_library(
         "dev.go",
         "fusefs.go",
         "init.go",
+        "inode_refs.go",
         "register.go",
         "request_list.go",
     ],
@@ -30,6 +42,7 @@ go_library(
         "//pkg/abi/linux",
         "//pkg/context",
         "//pkg/log",
+        "//pkg/refs",
         "//pkg/sentry/fsimpl/devtmpfs",
         "//pkg/sentry/fsimpl/kernfs",
         "//pkg/sentry/kernel",
diff --git a/pkg/sentry/fsimpl/fuse/fusefs.go b/pkg/sentry/fsimpl/fuse/fusefs.go
index 44021ee4b..9717c0e15 100644
--- a/pkg/sentry/fsimpl/fuse/fusefs.go
+++ b/pkg/sentry/fsimpl/fuse/fusefs.go
@@ -198,6 +198,7 @@ func (fs *filesystem) Release(ctx context.Context) {
 
 // inode implements kernfs.Inode.
 type inode struct {
+	inodeRefs
 	kernfs.InodeAttrs
 	kernfs.InodeNoDynamicLookup
 	kernfs.InodeNotSymlink
@@ -213,6 +214,7 @@ func (fs *filesystem) newInode(creds *auth.Credentials, mode linux.FileMode) *ke
 	i := &inode{}
 	i.InodeAttrs.Init(creds, linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), linux.ModeDirectory|0755)
 	i.OrderedChildren.Init(kernfs.OrderedChildrenOptions{})
+	i.EnableLeakCheck()
 	i.dentry.Init(i)
 
 	return &i.dentry
@@ -324,3 +326,8 @@ func (i *inode) Stat(ctx context.Context, fs *vfs.Filesystem, opts vfs.StatOptio
 
 	return statFromFUSEAttr(out.Attr, opts.Mask, fusefs.devMinor), nil
 }
+
+// DecRef implements kernfs.Inode.
+func (i *inode) DecRef(context.Context) {
+	i.inodeRefs.DecRef(i.Destroy)
+}