FROMLIST: fuse: revalidate: don't invalidate if interrupted

If the LOOKUP request triggered from fuse_dentry_revalidate() is
interrupted, then the dentry will be invalidated, possibly resulting in
submounts being unmounted.

Reported-by: Xu Rongbo <xurongbo@baidu.com>
Fixes: 9e6268db ("[PATCH] FUSE - read-write operations")
Cc: <stable@vger.kernel.org>
Change-Id: I8c62f5aeeb450de78c6a38a6f8728c900a0fc9bd
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Bug: 282905757
Bug: 300349748
Bug: 307663509
Link: https://lore.kernel.org/all/CAJfpegswN_CJJ6C3RZiaK6rpFmNyWmXfaEpnQUJ42KCwNF5tWw@mail.gmail.com/


Signed-off-by: Paul Lawrence <paullawrence@google.com>
Signed-off-by: chenxin <chenxinxin@xiaomi.corp-partner.google.com>
(cherry picked from commit 72198aea)