Fix user namespace leak

stable inclusion
from stable-5.10.80
commit 0e1709b2a07ad18742808a7088468b0b3477aa96
bugzilla: 185821 https://gitee.com/openeuler/kernel/issues/I4L7CG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0e1709b2a07ad18742808a7088468b0b3477aa96



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[ Upstream commit d5f458a9 ]

Fixes: 61ca2c4a ("NFS: Only reference user namespace from nfs4idmap struct instead of cred")
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>