From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 6C7DD1E379F for ; Fri, 13 Dec 2024 13:51:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734097874; cv=none; b=RJ5JK9ZBLKN0gu0zhDVohAycfFL8E2LliIYIy4UX2HjZStQbviKpfQUiMSllAzQGcXDeUZQ5aEtIJGDm1/mSN+fQ41vnSQmvN4ycVv0EOaLvvf7NziemkDnTbNYsxlzGmy+wDWg+Yp57/1QhxsvttwL3CIs7D8s9zziWrQRJsxw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734097874; c=relaxed/simple; bh=uaeI9J7rEoRhi5ZksmwE/88jFR1W/T6sdc10RyCTsN8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BlYQoKvbrTm8T7qOrSzCmeEau+kYHWNAw4opmHFGq3MxCb6sTt2enaxX6qynu4GeeXg4DPyI7eVldaUwLPxT52AeZbPe2ssExFwDwejIplvIPTt8cB5gGPfShnZ1h9eq/NOY++Hzyjj6xd8zJZdqsaxTImkdVVVpr5j3GiR3XGU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=R3sIVsAu; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="R3sIVsAu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734097871; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dahqI5gLkGfD05TuY+PqQn3pxJDwXGZGfLY3MOFYgVE=; b=R3sIVsAugDExB77D/kRmr7Bn6ZLuwbpIOP+iHDMl0apxDCVIeS3cAcxplaZXouyIjh5CRz tWlr4/kJ7Zymn/9zxOTlWyLiuPR3v99EeexhSc8Go+LulBLGDYjfwHYomBjzaH1wTrt7vp r/9L1ElMIjRwebB6/FSh/E3UwfrOQKQ= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-692-NQm--YxLM0SK64NOpZx29g-1; Fri, 13 Dec 2024 08:51:06 -0500 X-MC-Unique: NQm--YxLM0SK64NOpZx29g-1 X-Mimecast-MFC-AGG-ID: NQm--YxLM0SK64NOpZx29g Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2E4CD19560B5; Fri, 13 Dec 2024 13:51:02 +0000 (UTC) Received: from warthog.procyon.org.uk.com (unknown [10.42.28.48]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 058071955F40; Fri, 13 Dec 2024 13:50:56 +0000 (UTC) From: David Howells To: Christian Brauner Cc: David Howells , Max Kellermann , Ilya Dryomov , Xiubo Li , Trond Myklebust , Jeff Layton , Matthew Wilcox , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zilin Guan , Akira Yokosawa Subject: [PATCH 06/10] netfs: Remove redundant use of smp_rmb() Date: Fri, 13 Dec 2024 13:50:06 +0000 Message-ID: <20241213135013.2964079-7-dhowells@redhat.com> In-Reply-To: <20241213135013.2964079-1-dhowells@redhat.com> References: <20241213135013.2964079-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: ceph-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 From: Zilin Guan The function netfs_unbuffered_write_iter_locked() in fs/netfs/direct_write.c contains an unnecessary smp_rmb() call after wait_on_bit(). Since wait_on_bit() already incorporates a memory barrier that ensures the flag update is visible before the function returns, the smp_rmb() provides no additional benefit and incurs unnecessary overhead. This patch removes the redundant barrier to simplify and optimize the code. Signed-off-by: Zilin Guan Signed-off-by: David Howells cc: Akira Yokosawa cc: Jeff Layton cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20241207021952.2978530-1-zilin@seu.edu.cn/ --- fs/netfs/direct_write.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c index 88f2adfab75e..173e8b5e6a93 100644 --- a/fs/netfs/direct_write.c +++ b/fs/netfs/direct_write.c @@ -104,7 +104,6 @@ ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter * trace_netfs_rreq(wreq, netfs_rreq_trace_wait_ip); wait_on_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS, TASK_UNINTERRUPTIBLE); - smp_rmb(); /* Read error/transferred after RIP flag */ ret = wreq->error; if (ret == 0) { ret = wreq->transferred; From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 67BB8E7717D for ; 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Fri, 13 Dec 2024 13:51:02 +0000 (UTC) Received: from warthog.procyon.org.uk.com (unknown [10.42.28.48]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 058071955F40; Fri, 13 Dec 2024 13:50:56 +0000 (UTC) From: David Howells To: Christian Brauner Subject: [PATCH 06/10] netfs: Remove redundant use of smp_rmb() Date: Fri, 13 Dec 2024 13:50:06 +0000 Message-ID: <20241213135013.2964079-7-dhowells@redhat.com> In-Reply-To: <20241213135013.2964079-1-dhowells@redhat.com> References: <20241213135013.2964079-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-cifs@vger.kernel.org, Max Kellermann , v9fs@lists.linux.dev, Akira Yokosawa , Jeff Layton , linux-nfs@vger.kernel.org, Matthew Wilcox , linux-kernel@vger.kernel.org, David Howells , linux-mm@kvack.org, ceph-devel@vger.kernel.org, Zilin Guan , linux-fsdevel@vger.kernel.org, netfs@lists.linux.dev, Ilya Dryomov , Xiubo Li , linux-erofs@lists.ozlabs.org, linux-afs@lists.infradead.org, Trond Myklebust Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" From: Zilin Guan The function netfs_unbuffered_write_iter_locked() in fs/netfs/direct_write.c contains an unnecessary smp_rmb() call after wait_on_bit(). Since wait_on_bit() already incorporates a memory barrier that ensures the flag update is visible before the function returns, the smp_rmb() provides no additional benefit and incurs unnecessary overhead. This patch removes the redundant barrier to simplify and optimize the code. Signed-off-by: Zilin Guan Signed-off-by: David Howells cc: Akira Yokosawa cc: Jeff Layton cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20241207021952.2978530-1-zilin@seu.edu.cn/ --- fs/netfs/direct_write.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c index 88f2adfab75e..173e8b5e6a93 100644 --- a/fs/netfs/direct_write.c +++ b/fs/netfs/direct_write.c @@ -104,7 +104,6 @@ ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter * trace_netfs_rreq(wreq, netfs_rreq_trace_wait_ip); wait_on_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS, TASK_UNINTERRUPTIBLE); - smp_rmb(); /* Read error/transferred after RIP flag */ ret = wreq->error; if (ret == 0) { ret = wreq->transferred;