From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 86B1A484230 for ; Wed, 26 Aug 2026 20:27:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787776027; cv=none; b=a7yfpQlIukv0UrP5QRdopRskgnc0Hy4z0KZVDK5Q1Ol0Q6/EyeFnYQkrPG7/KIcd0PqB47ro+6wn4U4bvwI6aINqqCkqa12NAKCs4b0uQ4EdL/PMaHwq5zEngFRNcL+kN2aVJtwca8gT0XxSjfgVBmtX8HOhPpAmmsLjNAaH8r8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787776027; c=relaxed/simple; bh=6Zathy3cLcEXNirZWfsFyg/FrLZFmWjr8rAvDCURITM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=J1TXl9W9r3HX4V4OR7bK9uCB864TsGtrXvvuv0zwGqOsO85VxvyC89/aKLjymmybIgazILyArV/rCArDnxofCMW7UyldShesPM7de2161Sv/Ux4qUnjhQuQ2SZ2e7xDTWMcvgr0OICB9M4icRBbh15SNIEhTpol0F4Cufh+uU2k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=afPeNFCL; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="afPeNFCL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6FF71F00A3F; Wed, 26 Aug 2026 20:27:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787776025; bh=aaAOfKXVNvFQ3AEZwAQI5sRDD7x7zfpWwOeZRVfms/A=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=afPeNFCLXlCH2851TmWDpy/fy5A9zqXrKOpiwaxzqIoM55TwwsPmBbQIPslAi9V4j NF7Qgv2FX8rGCbez8UAGOXtPPFZWRIa1J1D/8N9T/3FujCYN27zy9oM8nAecZ1BQcG LeDpkcc8TvYZrkOtxyeNl2NyHZgQNci2fjvOfNPBXjil/HL4DC5PfQH2xxGlbQvYnl 29O8flVOhZZ9V1lwc/zCTO4rplkgLS3bdGQo2hUGNJWM0vpFEV8TcDvYnuTAF082YH +S9YRgS37aHWZgweAoGmq9CFAhiqr7f6FvkJ5VgU/50jBl087AZ7IOcbF1pNRqbkkj mEfH18tEfEqfQ== From: Chuck Lever Date: Wed, 26 Aug 2026 16:26:53 -0400 Subject: [PATCH 3/7] SUNRPC: Record last-request timestamp on svc_xprt Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260826-duplicate-reply-cache-v1-3-b1d51e1af5c7@kernel.org> References: <20260826-duplicate-reply-cache-v1-0-b1d51e1af5c7@kernel.org> In-Reply-To: <20260826-duplicate-reply-cache-v1-0-b1d51e1af5c7@kernel.org> To: Jeff Layton , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: Rick Macklem , linux-nfs@vger.kernel.org, Chuck Lever X-Mailer: b4 0.16-dev-da966 X-Developer-Signature: v=1; a=openpgp-sha256; l=1854; i=cel@kernel.org; h=from:subject:message-id; bh=6Zathy3cLcEXNirZWfsFyg/FrLZFmWjr8rAvDCURITM=; b=owEBbQKS/ZANAwAKATNqszNvZn+XAcsmYgBqj0wVjDOFkq586R2M91LV2trLgZLhqq+Xejkmu 5XVHteuFQWJAjMEAAEKAB0WIQQosuWwEobfJDzyPv4zarMzb2Z/lwUCao9MFQAKCRAzarMzb2Z/ l7cLD/4+Lq8B9GPBRCHFD/Erh4QZaVkjxJ9U1H1p8aJyeXiOf6vFqdOEbvhBx1AxqiY8LdYU8RU NVpgCUR5gX7ViDeR2R7x4CM63VWt2A9QHdHYEJ4V1UUafZJ3mn1FXKCS1BOC02A7n+Ky8x1Pgah MGs/wxcV6F0XHFqlclG/o6dEiwrtuurtkLpDAtDUBQor+ASk8wDe+8YeeioHqa50YvcASYN7wrs TJk+l6xuq6e1NdGUSXFRpBoIxXo1CSF4ZUuXQTqqbJkcLimbyLrklcCljNblv8CjhpZpHPa92+M 3Il9bV5tvluB0MaoIK4CCB10f1haIulZoObZddomwe7n5sXIx4qdhZvd9SZWBVgdyKWhMRrU8FS 9AIdFGVp38mFBTiA685seyYXVMeV6rUZhBmfGnFpeJqkpoXB+ypupeEB2CrkWtvaAyyjrbgDsG9 ZDBcls2gv85khW5+LajaL0stm5mBTN6yQJ3Ow/TSO4yLiGIlWHp24TnkDdOETM79DANSh6rI24P HZHhKyuX9hg01Ag4w4b1sPznFt4RRZqhB8nJQZw8RQqPSgaAqV88tQguuLN3TWjohlp3q2VLLH7 KRmcH706zbTTX9S2iZu7etH9+JzQ3zSuODif55FiqKyDIJw2l24dhtXxAGRVId3559KG6iG8pBV JXz+2jDd729GIcA== X-Developer-Key: i=cel@kernel.org; a=openpgp; fpr=28B2E5B01286DF243CF23EFE336AB3336F667F97 On a connection-oriented transport, the arrival of a later request suggests the client received the prior reply. It is not proof: a client with several requests outstanding sends the next one without waiting for a reply. Add xpt_last_recv to struct svc_xprt and update it in svc_handle_xprt() after each successful xpo_recvfrom(). A revisited deferred request leaves it alone, since that request arrived before the deferral and is not fresh client activity. The DRC reads this value as a best-effort signal that a completed reply has been delivered. Signed-off-by: Chuck Lever --- include/linux/sunrpc/svc_xprt.h | 1 + net/sunrpc/svc_xprt.c | 7 +++++++ 2 files changed, 8 insertions(+) diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h index 88d73da5f46f..53ed073640a6 100644 --- a/include/linux/sunrpc/svc_xprt.h +++ b/include/linux/sunrpc/svc_xprt.h @@ -78,6 +78,7 @@ struct svc_xprt { struct net *xpt_net; netns_tracker ns_tracker; const struct cred *xpt_cred; + unsigned long xpt_last_recv; /* jiffies of last request */ struct rpc_xprt *xpt_bc_xprt; /* NFSv4.1 backchannel */ struct rpc_xprt_switch *xpt_bc_xps; /* NFSv4.1 backchannel */ }; diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index ca10ef965443..1d4a40627244 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -914,6 +914,13 @@ static void svc_handle_xprt(struct svc_rqst *rqstp, struct svc_xprt *xprt) clear_bit(XPT_OLD, &xprt->xpt_flags); + /* + * A deferred request is a replay of one that arrived + * earlier, not fresh client activity on this connection. + */ + if (!rqstp->rq_deferred) + WRITE_ONCE(xprt->xpt_last_recv, jiffies); + rqstp->rq_chandle.defer = svc_defer; if (serv->sv_stats) -- 2.55.0