From patchwork Fri Dec 13 13:50:06 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 13907124 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 5E68B1E379F for ; Fri, 13 Dec 2024 13:51:10 +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=1734097872; cv=none; b=duxOT56cfTHTP2ElDXGtboi7bZlGkKlbEkHX9K0YLJImzkRAQDJMGyViUsQvTqM6b7nnoNgjbWuDjIaxSHXD690KQv7kaHFK5J1xwokleE7QET8ps9MPMpPc9FR9/B39w8tY9X5HJxPjeTF9wonWGZy0ZWg1CZQaIHd1M5tmIB0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734097872; c=relaxed/simple; bh=uaeI9J7rEoRhi5ZksmwE/88jFR1W/T6sdc10RyCTsN8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=G4lxAkBv++G9dELMg4X3oSLWPo7WCxbUDLKDSZQ6jOrjUvaDCCb5Y2ahiNieblT3Podgr66f5yRDR2bb6c/n24S8V6k/nVgSnq5v78JWUJXZM6s1RclC43p1c0fZkPKZyHUi37QcH95ux74GstwR2pZbDCFEvTIfxvujK7rvZoA= 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=Opmb7oMZ; 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="Opmb7oMZ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734097869; 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=Opmb7oMZAhU19zFew4Q9s26TEEmklbZ5TZuYFqxDphnYwpLHeZXyUlUyScVyHcke6r3zbL VHWOeS36i2WmfsHH/Bx0ky0XZ28jnIWBIa4wJbLZ0+IUMlhvv0Xlq2eIkTeHfKiJc9gm0D u8KznsG5+25p0n4DvHaG3V2MMw6MUYk= 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: v9fs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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/ Reviewed-by: Akira Yokosawa --- 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;