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 C3F4D306757 for ; Tue, 23 Jun 2026 16:29:16 +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=1782232157; cv=none; b=NpPh997+QQUdzfjKZlR79k07oolTlLs5IuM9wnLIru9P0dXsFbHbk3wAtdWA18CQ7tW76xFqjOlu6wByjWWRfhVIaFh3Sca24zrxqmY17uSAfULi/4HK2z4auaWqkSYdhNeWreG7s4XbBeLdvZwyJwbrW7bYnAjse8zTnR+lVtc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782232157; c=relaxed/simple; bh=rRq05R5+ZxwxtgSXNIyu0FuVwAV77cFRgAvPdacijuE=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=mel6CJk8KQXacKQnd3DyjnzdU/h68qP6pWRAjE3sKb3jJ6+dLoPtIcXnxK6MPWW/EDYYoGBHDg9H7NHYW+gLRZe2yB/7qQKbKfuksooKLxr5n6IzWVuG5fOGz50eTZduDXZVThgqIeH/X8lAUvt30n+jUiZxt5TsDYS920MnO94= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eCc+SDLp; 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="eCc+SDLp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AAD421F000E9; Tue, 23 Jun 2026 16:29:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782232156; bh=rRq05R5+ZxwxtgSXNIyu0FuVwAV77cFRgAvPdacijuE=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=eCc+SDLpboC7WGwLpuc4it+sl5I1J62ROapz5AQLG9/V9622CTE62Jc57fB9qDSI1 SdIBQs0xzk4UthwmGshbHtEOLcIGTQNBkGsjgbI8PbZ75I6stBO60ineNNXnZLXvTx plnN0FW+6sUp2VnFvR4CYtlmCYZl0zknawQJTA1AcWoGrZrOXfh9IdHm0PkhatYNWq OUwfDnLqzsrkAiQKkzdWI3Lk2EMCBztV19wyV6coWMihmSXGVjIoYTWdOELhdcZYnc x+La+EWg+pFEv6LYFHy5WYyn1bdmuGcSLM7u0Qw6hJk0qBLp7dNxbeqMJ4g4AQ4xmH MpFPcFeVxKpdA== Message-ID: <3aab8cd1b42edbd1cbfc3981fd3624ab8e988993.camel@kernel.org> Subject: Re: NFS delegations behavior analysis From: Trond Myklebust To: Benjamin Coddington Cc: Jeff Layton , "Mkrtchyan, Tigran" , Piyush Sachdeva , linux-nfs , Chuck Lever , sfrench@samba.org, sprasad@microsoft.com, vaibsharma@microsoft.com Date: Tue, 23 Jun 2026 12:29:14 -0400 In-Reply-To: References: <0b39c1e01a92f99fe456c76523ec7f3aa5dc1a81.camel@kernel.org> <455619640.1622514.1782212671358.JavaMail.zimbra@desy.de> <227140ce94ebe4186d02b081489a58f32b878ec4.camel@kernel.org> <4323491E-64A0-4883-8343-5EB569A0D81A@hammerspace.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 (3.60.2-1.fc44) Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2026-06-23 at 09:32 -0400, Benjamin Coddington wrote: > On 23 Jun 2026, at 9:11, Benjamin Coddington wrote: >=20 > > .... er - so with directory delegations, can we simply re-hydrate > > the dentry > > cache from the directory page mappings if the delegation is still > > valid? > > Does the directory delegation pin the mapping?=C2=A0 Clearly I need to > > look at > > the code.. >=20 > .. right - we don't keep the file attributes in the mappings today.=C2=A0 > And, > more to the point - the directory delegation doesn't protect those > file > attributes either.=C2=A0 We'd need NOTIFY4_CHANGE_CHILD_ATTRIBUTES > implemented. >=20 > Ben Unlike delegations, notifications are asynchronous by design. Upon reception of a notification, you may deduce that you should revalidate the attributes on a file. However the absence of that notification is insufficient to deduce that it is safe not to revalidate those attributes. So when it comes to informing the client whether to use READDIR or READDIRPLUS, I'm sceptical concerning the value of throwing NOTIFY4_CHANGE_CHILD_ATTRS at the problem. --=20 Trond Myklebust Linux NFS client maintainer, Hammerspace trondmy@kernel.org, trond.myklebust@hammerspace.com