From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9183623DE; Fri, 9 Aug 2024 00:00:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723161646; cv=none; b=ilGMrvAMatcUF/UPwOhlNo+LpL93jCQBAba5NhV8EClvSfDFLlAdFmg5aYJPhpwYadV8ok+wsAqwyirFa8uy5WuLMAwjOBaOPVwatdkgiHTb3EZ3WGNtWyi+KkxALrxMQ06EQSzX9vDybC992Shprnly7GTILEK8GUsKPGon0gs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723161646; c=relaxed/simple; bh=Jl7/6yxGYz+l6WkVBWiWZ6jL7unPDbOfR3JUeia4tLg=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=DZaoNHMw1/2Ga1t5ZTSUtHehgDDXG7pEwX/IDxMQ1PPwRpcpZFgDQ+0XIPCZF/DN2hnRILmPD5kn5Coo+exzFUq9bDm+fzy15JjfZMwNzptEzNziZ8LJ5o1xmzS4w0FrJkRtAokHDJmMl0gvj2oyIWg6QivV/yXYiqOvlLv0zFg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XoKXeSOz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XoKXeSOz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 95110C32782; Fri, 9 Aug 2024 00:00:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1723161646; bh=Jl7/6yxGYz+l6WkVBWiWZ6jL7unPDbOfR3JUeia4tLg=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=XoKXeSOzGdh6dZ5157CyrLl2q2/EKEB6Y6ANgYOzhjF44JkjEy8VOooRL1oXvAdmT gZjeLTjs+LvCacHK+newdFi7GLn/DB176G6R45GESPp9z621G+Xydbmv/5L0IxLbgO yGwEdBG0ZySz846vytakd6BpXTAIAhG4VFezOlcKm3DwTxlP1fHZ098pryTz0LsXEJ 7YB6j9XUwaWLpne5sKDDPyOTH3VsLQw2GZ/Wu3IkyEWcYjWdrTmznzEDOdGfEGSJJv GitXmleEXahsvO8tKvnzzPS66bBxxb26F7vlFEQCq80eUpItbkfZgvgF+71g3OcfJ1 Yl8IvHoewpZHQ== Message-ID: <796973ee97c0b16761b41f510b852725da07eed7.camel@kernel.org> Subject: Re: [PATCH v6 1/9] fs: add infrastructure for multigrain timestamps From: Jeff Layton To: Mateusz Guzik Cc: Alexander Viro , Christian Brauner , Jan Kara , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 08 Aug 2024 20:00:44 -0400 In-Reply-To: References: <20240715-mgtime-v6-0-48e5d34bd2ba@kernel.org> <20240715-mgtime-v6-1-48e5d34bd2ba@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 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2024 at 08:48:52AM -0400, Jeff Layton wrote: > > diff --git a/fs/stat.c b/fs/stat.c > > index 6f65b3456cad..df7fdd3afed9 100644 > > --- a/fs/stat.c > > +++ b/fs/stat.c > > @@ -26,6 +26,32 @@ > > #include "internal.h" > > #include "mount.h" > > =20 > > +/** > > + * fill_mg_cmtime - Fill in the mtime and ctime and flag ctime as QUER= IED > > + * @stat: where to store the resulting values > > + * @request_mask: STATX_* values requested > > + * @inode: inode from which to grab the c/mtime > > + * > > + * Given @inode, grab the ctime and mtime out if it and store the resu= lt > > + * in @stat. When fetching the value, flag it as queried so the next w= rite > > + * will ensure a distinct timestamp. > > + */ > > +void fill_mg_cmtime(struct kstat *stat, u32 request_mask, struct inode= *inode) > > +{ > > + atomic_t *pcn =3D (atomic_t *)&inode->i_ctime_nsec; > > + > > + /* If neither time was requested, then don't report them */ > > + if (!(request_mask & (STATX_CTIME|STATX_MTIME))) { > > + stat->result_mask &=3D ~(STATX_CTIME|STATX_MTIME); > > + return; > > + } > > + > > + stat->mtime =3D inode_get_mtime(inode); > > + stat->ctime.tv_sec =3D inode->i_ctime_sec; > > + stat->ctime.tv_nsec =3D ((u32)atomic_fetch_or(I_CTIME_QUERIED, pcn)) = & ~I_CTIME_QUERIED; > > +} > > +EXPORT_SYMBOL(fill_mg_cmtime); > > + >=20 > [trimmed the ginormous CC] >=20 > This performs the atomic every time (as in it sets the flag even if it > was already set), serializing all fstats and reducing scalability of > stat of the same file. >=20 > Bare minimum it should be conditional -- if the flag is already set, > don't dirty anything. >=20 > Even that aside adding an atomic to stat is a bummer, but off hand I > don't have a good solution for that. >=20 > Anyhow, this being in -next, perhaps the conditional dirty can be > massaged into the thing as present? There are some cosmetic choices to > be made how to express, may be the fastest if you guys just augment it > however you see fit. >=20 > If not I can submit a patch tomorrow. I'm fine with that change. It should simple enough. --=20 Jeff Layton