We will write /proc/net/rpc/xxx/flush if we want to clean cache_detail. This updates nextcheck to the current time and calls cache_flush --> cache_clean to clean cache_detail. If we write this interface again within one second, it will only increase flush_time and nextcheck without actually cleaning cache_detail. Therefore, if we keep writing this interface repeatedly within one second, flush_time and nextcheck will keep increasing, even far exceeding the current time, making it impossible to clear cache_detail through the flush interface or cache_cleaner. If someone frequently calls the flush interface, we should immediately clean the corresponding cache_detail instead of continuously accumulating nextcheck. Signed-off-by: Li Lingfeng <lilingfeng3@xxxxxxxxxx> --- net/sunrpc/cache.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index 059f6ef1ad18..73668df0450b 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -1531,9 +1531,13 @@ static ssize_t write_flush(struct file *file, const char __user *buf, * or by one second if it has already reached the current time. * Newly added cache entries will always have ->last_refresh greater * that ->flush_time, so they don't get flushed prematurely. + * + * If someone frequently calls the flush interface, we should + * immediately clean the corresponding cache_detail instead of + * continuously accumulating nextcheck. */ - if (cd->flush_time >= now) + if (cd->flush_time >= now && cd->flush_time < (now + 5)) now = cd->flush_time + 1; cd->flush_time = now; -- 2.31.1
