hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4SK3S
CVE: NA

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Add statistics for usage of reliable page cache, Item "ReliableFileCache"
in /proc/meminfo show the usage of reliable page cache.
Signed-off-by: NChen Wandun <chenwandun@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Reviewed-by: Kefeng Wang<wangkefeng.wang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>