From nobody Thu Nov 28 10:41:10 2024 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 AC242217914; Wed, 2 Oct 2024 18:50:03 +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=1727895003; cv=none; b=fxMuQ12YsP+uUKHe0CxWVzcSmTzFOugM6wooCMP1LYr2vOx2YA5du1AKfQYPPvMPNdjxCkEYtE3CQXgA3ZML9ZXbmbPDC1rvP6yo+Uz2E67WA5WLaF/3JSKXrTi1CbNkBQpkYAJXtOlgqJ/DpNa9Gop2eFP87Kr+M0KY0monSSw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727895003; c=relaxed/simple; bh=607LRAQ5lYI/rYHwJWudAw3VqFTtnPId8/VXkMTcyVI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=qxwJEn6L26SnDqI50EfDJoZMo92/qQsB4SMSdICEh1jYme2yR6k8gUE8srYisy5aE/seDTUENlsau2Zxpa0OZQGNZJ1WV+JsYmHO4mvMos5GASYezoIRh12ut2DgreI+1BuPDo3S747HTl+hLFeiT/r1JCGb4zMy9zczIdkQqHE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=m29kn21o; 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="m29kn21o" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F247C4CED6; Wed, 2 Oct 2024 18:50:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727895003; bh=607LRAQ5lYI/rYHwJWudAw3VqFTtnPId8/VXkMTcyVI=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=m29kn21oThOWn8FA3lIOxu891/RPN4jgBUyw5AcmTnYQW3nxAervpGlIeLy3HbIcv JFgHvNsfXUryLA6XYI9KgtNURXTbcYLjIxf6QiqValFyd36gG4pXxJJon+0/ZWLhDb cB+au0L/oDT2l10Nf0T1LV2RX5mCJhaLiBbZGNcrKOlXfLRTz53NBq2CIwq8BCh/zF AG3ySqlcVwUCQcyqUivBA/Zm1gLSLGw5RfwpH1doHBf6Nk2MWEhb0PcrV5MwKD7f1F XWF1vbWNym0+i8+ZAinFzZlOpVmLnpoxkSDBFp7IS3ykdXbn1De9CGkb/0DONHW4w9 IZaD+B9dT2LYQ== From: Jeff Layton Date: Wed, 02 Oct 2024 14:49:32 -0400 Subject: [PATCH v9 04/12] fs: handle delegated timestamps in setattr_copy_mgtime Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20241002-mgtime-v9-4-77e2baad57ac@kernel.org> References: <20241002-mgtime-v9-0-77e2baad57ac@kernel.org> In-Reply-To: <20241002-mgtime-v9-0-77e2baad57ac@kernel.org> To: John Stultz , Thomas Gleixner , Stephen Boyd , Alexander Viro , Christian Brauner , Jan Kara , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Randy Dunlap , Chandan Babu R , "Darrick J. Wong" , Theodore Ts'o , Andreas Dilger , Chris Mason , Josef Bacik , David Sterba , Hugh Dickins , Andrew Morton , Chuck Lever , Vadim Fedorenko Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org, Jeff Layton X-Mailer: b4 0.14.1 X-Developer-Signature: v=1; a=openpgp-sha256; l=6217; i=jlayton@kernel.org; h=from:subject:message-id; bh=607LRAQ5lYI/rYHwJWudAw3VqFTtnPId8/VXkMTcyVI=; b=owEBbQKS/ZANAwAIAQAOaEEZVoIVAcsmYgBm/ZXM5rS0bxHUPi1uZgMZGm2lnd37dfflL6NJB yztoxeouX6JAjMEAAEIAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCZv2VzAAKCRAADmhBGVaC FYkzD/9PTpFx52ZO8A+U0V3o8KkeLeBWD+hZ1Sx6vNZvIFxjnqkOsTXC4Y4vSpq75YZLAUcZfmj z6YQNmZaJWgVPZnO8Md9u62OezZuDjmnZZ7+9Xqwyc8+/fMpu7AiLwv9F3LW8qZ0QuEwFZmpdLG l9wo9XpuoLGcAOunDit8Pi7nS45zJ3yeEwLtdUGwTGY8ue3SnNVNDKsMyAjKkCiLXUgaL6qDE9A FMGf3pyRHNhYbkOJQK9Gi41M+47BttNnuYCVLA5ZbPibqbFovLKbvfbP7EQZjRfELrIDhVU8B2B ycIFDvYCfjUmaBNl0BOv21FeHfWOApYJWntTioRONDy3Yh5/oaJqYdpeSXxIZFoNtG1G1mWNjk7 mBETrDuITMf9g3Yr6+Xf3KKdb19q6Uw/SVcFK/Fqm2FrvVZSpjxaGc8UJ4TGEufO/1It62fQPu2 YFyelm7XMplEeuGXEuDcOxDXFMr/TgjmEpiOxNblirKPjxV8soK4A9gx6bR4MgBA+33CWaqeo2/ J6WnYTgFCLgL14H8wKWzVmOcYJl6tXCD07d4GRYA+cijQTkL5VPVlPTPjgQucVnzVxRsRYfXquL xP6iHiQWaJzD1OhEXOLzVrnoh1cr/p5xu2HPKSw5GCLdQqUTnH5603gpWXAPXtFAWkYyOSTb1NJ Mb24SKJzynhFlhA== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 An update to the inode ctime typically requires the latest clock value possible. The exception to this rule is when there is a nfsd write delegation and the server is proxying timestamps from the client. When nfsd gets a CB_GETATTR response, update the timestamp value in the inode to the values that the client is tracking. The client doesn't send a ctime value (since that's always determined by the exported filesystem), but it can send a mtime value. In the case where it does, update the ctime to a value commensurate with that instead of the current time. If ATTR_DELEG is set, then use ia_ctime value instead of setting the timestamp to the current time. With the addition of delegated timestamps, the server may receive a request to update only the atime, which doesn't involve a ctime update. Trust the ATTR_CTIME flag in the update and only update the ctime when it's set. Tested-by: Randy Dunlap # documentation bits Reviewed-by: Jan Kara Signed-off-by: Jeff Layton --- fs/attr.c | 28 +++++++++++++-------- fs/inode.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++= ++++ include/linux/fs.h | 2 ++ 3 files changed, 93 insertions(+), 10 deletions(-) diff --git a/fs/attr.c b/fs/attr.c index 0309c2bd8afa..c614b954bda5 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -286,16 +286,20 @@ static void setattr_copy_mgtime(struct inode *inode, = const struct iattr *attr) unsigned int ia_valid =3D attr->ia_valid; struct timespec64 now; =20 - /* - * If the ctime isn't being updated then nothing else should be - * either. - */ - if (!(ia_valid & ATTR_CTIME)) { - WARN_ON_ONCE(ia_valid & (ATTR_ATIME|ATTR_MTIME)); - return; + if (ia_valid & ATTR_CTIME) { + /* + * In the case of an update for a write delegation, we must respect + * the value in ia_ctime and not use the current time. + */ + if (ia_valid & ATTR_DELEG) + now =3D inode_set_ctime_deleg(inode, attr->ia_ctime); + else + now =3D inode_set_ctime_current(inode); + } else { + /* If ATTR_CTIME isn't set, then ATTR_MTIME shouldn't be either. */ + WARN_ON_ONCE(ia_valid & ATTR_MTIME); } =20 - now =3D inode_set_ctime_current(inode); if (ia_valid & ATTR_ATIME_SET) inode_set_atime_to_ts(inode, attr->ia_atime); else if (ia_valid & ATTR_ATIME) @@ -354,8 +358,12 @@ void setattr_copy(struct mnt_idmap *idmap, struct inod= e *inode, inode_set_atime_to_ts(inode, attr->ia_atime); if (ia_valid & ATTR_MTIME) inode_set_mtime_to_ts(inode, attr->ia_mtime); - if (ia_valid & ATTR_CTIME) - inode_set_ctime_to_ts(inode, attr->ia_ctime); + if (ia_valid & ATTR_CTIME) { + if (ia_valid & ATTR_DELEG) + inode_set_ctime_deleg(inode, attr->ia_ctime); + else + inode_set_ctime_to_ts(inode, attr->ia_ctime); + } } EXPORT_SYMBOL(setattr_copy); =20 diff --git a/fs/inode.c b/fs/inode.c index 53f56f6e1ff2..7d1ede60e549 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -2717,6 +2717,79 @@ struct timespec64 inode_set_ctime_current(struct ino= de *inode) } EXPORT_SYMBOL(inode_set_ctime_current); =20 +/** + * inode_set_ctime_deleg - try to update the ctime on a delegated inode + * @inode: inode to update + * @update: timespec64 to set the ctime + * + * Attempt to atomically update the ctime on behalf of a delegation holder. + * + * The nfs server can call back the holder of a delegation to get updated + * inode attributes, including the mtime. When updating the mtime, update + * the ctime to a value at least equal to that. + * + * This can race with concurrent updates to the inode, in which + * case the update is skipped. + * + * Note that this works even when multigrain timestamps are not enabled, + * so it is used in either case. + */ +struct timespec64 inode_set_ctime_deleg(struct inode *inode, struct timesp= ec64 update) +{ + struct timespec64 now, cur_ts; + u32 cur, old; + + /* pairs with try_cmpxchg below */ + cur =3D smp_load_acquire(&inode->i_ctime_nsec); + cur_ts.tv_nsec =3D cur & ~I_CTIME_QUERIED; + cur_ts.tv_sec =3D inode->i_ctime_sec; + + /* If the update is older than the existing value, skip it. */ + if (timespec64_compare(&update, &cur_ts) <=3D 0) + return cur_ts; + + ktime_get_coarse_real_ts64_mg(&now); + + /* Clamp the update to "now" if it's in the future */ + if (timespec64_compare(&update, &now) > 0) + update =3D now; + + update =3D timestamp_truncate(update, inode); + + /* No need to update if the values are already the same */ + if (timespec64_equal(&update, &cur_ts)) + return cur_ts; + + /* + * Try to swap the nsec value into place. If it fails, that means + * it raced with an update due to a write or similar activity. That + * stamp takes precedence, so just skip the update. + */ +retry: + old =3D cur; + if (try_cmpxchg(&inode->i_ctime_nsec, &cur, update.tv_nsec)) { + inode->i_ctime_sec =3D update.tv_sec; + mgtime_counter_inc(mg_ctime_swaps); + return update; + } + + /* + * Was the change due to another task marking the old ctime QUERIED? + * + * If so, then retry the swap. This can only happen once since + * the only way to clear I_CTIME_QUERIED is to stamp the inode + * with a new ctime. + */ + if (!(old & I_CTIME_QUERIED) && (cur =3D=3D (old | I_CTIME_QUERIED))) + goto retry; + + /* Otherwise, it was a new timestamp. */ + cur_ts.tv_sec =3D inode->i_ctime_sec; + cur_ts.tv_nsec =3D cur & ~I_CTIME_QUERIED; + return cur_ts; +} +EXPORT_SYMBOL(inode_set_ctime_deleg); + /** * in_group_or_capable - check whether caller is CAP_FSETID privileged * @idmap: idmap of the mount @inode was found from diff --git a/include/linux/fs.h b/include/linux/fs.h index eff688e75f2f..ea7ed437d2b1 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1544,6 +1544,8 @@ static inline bool fsuidgid_has_mapping(struct super_= block *sb, =20 struct timespec64 current_time(struct inode *inode); struct timespec64 inode_set_ctime_current(struct inode *inode); +struct timespec64 inode_set_ctime_deleg(struct inode *inode, + struct timespec64 update); =20 static inline time64_t inode_get_atime_sec(const struct inode *inode) { --=20 2.46.2