linux-kernel - [PATCH 1/2] sunrpc: update nextcheck time when adding new cache entries

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Message-ID: <20250301064836.3285906-2-leo.lilong@huawei.com>
Date: Sat, 1 Mar 2025 14:48:35 +0800
From: Long Li <leo.lilong@...wei.com>
To: <chuck.lever@...cle.com>, <jlayton@...nel.org>, <neilb@...e.de>,
	<okorniev@...hat.com>, <Dai.Ngo@...cle.com>, <tom@...pey.com>,
	<trondmy@...nel.org>, <anna@...nel.org>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<horms@...nel.org>
CC: <linux-nfs@...r.kernel.org>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <yi.zhang@...wei.com>,
	<leo.lilong@...wei.com>, <yangerkun@...wei.com>, <lonuxli.64@...il.com>
Subject: [PATCH 1/2] sunrpc: update nextcheck time when adding new cache entries

The cache_detail structure uses a "nextcheck" field to control hash table
scanning intervals. When a table scan begins, nextcheck is set to current
time plus 1800 seconds. During scanning, if cache_detail is not empty and
a cache entry's expiry time is earlier than the current nextcheck, the
nextcheck is updated to that expiry time.

This mechanism ensures that:
1) Empty cache_details are scanned every 1800 seconds to avoid unnecessary
   scans
2) Non-empty cache_details are scanned based on the earliest expiry time
   found

However, when adding a new cache entry to an empty cache_detail, the
nextcheck time was not being updated, remaining at 1800 seconds. This
could delay cache cleanup for up to 1800 seconds, potentially blocking
threads(such as nfsd) that are waiting for cache cleanup.

Fix this by updating the nextcheck time whenever a new cache entry is
added.

Signed-off-by: Long Li <leo.lilong@...wei.com>
---
 net/sunrpc/cache.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index 004cdb59f010..d12ab3175d05 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -135,6 +135,8 @@ static struct cache_head *sunrpc_cache_add_entry(struct cache_detail *detail,

 	hlist_add_head_rcu(&new->cache_list, head);
 	detail->entries++;
+	if (detail->nextcheck > new->expiry_time)
+		detail->nextcheck = new->expiry_time + 1;
 	cache_get(new);
 	spin_unlock(&detail->hash_lock);

-- 
2.39.2