From 9a81ef42b238b28829a46ecf13c7aacb79b9b3ac Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Fri, 27 Mar 2020 11:53:09 -0400 Subject: [PATCH] SUNRPC/cache: don't allow invalid entries to be flushed Trond points out in commit 277f27e2f277 ("SUNRPC/cache: Allow garbage collection of invalid cache entries") that we allow invalid cache entries to persist indefinitely. That fix, however, reintroduces the problem fixed by Kinglong Mee's commit d6fc8821c2d2 ("SUNRPC/Cache: Always treat the invalid cache as unexpired"), where an invalid cache entry is immediately removed by a flush before mountd responds to it. The result is that the server thread that should be waiting for mountd to fill in that entry instead gets an -ETIMEDOUT return from cache_check(). Symptoms are the server becoming unresponsive after a restart, reproduceable by running pynfs 4.1 test REBT5. Instead, take a compromise approach: allow invalid cache entries to be removed after they expire, but not to be removed by a cache flush. Fixes: 277f27e2f277 ("SUNRPC/cache: Allow garbage collection ... ") Signed-off-by: J. Bruce Fields Signed-off-by: Chuck Lever --- include/linux/sunrpc/cache.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h index 532cdbda43da0..10891b70fc7b6 100644 --- a/include/linux/sunrpc/cache.h +++ b/include/linux/sunrpc/cache.h @@ -209,8 +209,11 @@ static inline void cache_put(struct cache_head *h, struct cache_detail *cd) static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h) { - return (h->expiry_time < seconds_since_boot()) || - (detail->flush_time >= h->last_refresh); + if (h->expiry_time < seconds_since_boot()) + return true; + if (!test_bit(CACHE_VALID, &h->flags)) + return false; + return detail->flush_time >= h->last_refresh; } extern int cache_check(struct cache_detail *detail,