[PATCH] utimes: Clamp the timestamps in notify_change()

From: Amir Goldstein <amir73il@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linux-nfs@vger.kernel.org, Miklos Szeredi <miklos@szeredi.hu>,
	y2038@lists.linaro.org, Jeff Layton <jlayton@kernel.org>,
	linux-unionfs@vger.kernel.org,
	"J . Bruce Fields" <bfields@fieldses.org>,
	Deepa Dinamani <deepa.kernel@gmail.com>,
	linux-fsdevel@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>
Subject: [PATCH] utimes: Clamp the timestamps in notify_change()
Date: Sun, 24 Nov 2019 21:31:45 +0200	[thread overview]
Message-ID: <20191124193145.22945-1-amir73il@gmail.com> (raw)

Push clamping timestamps down the call stack into notify_change(), so
in-kernel callers like nfsd and overlayfs will get similar timestamp
set behavior as utimes.

Suggested-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 42e729b9ddbb ("utimes: Clamp the timestamps before update")
Cc: stable@vger.kernel.org # v5.4
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---

Arnd,

This fixes xfstest generic/402 when run with -overlay setup.
Note that running the test requires latest xfstests with:
 acb2ba78 - overlay: support timestamp range check

I had previously posted a fix specific for overlayfs [1],
but Miklos suggested this more generic fix, which should also
serve nfsd and other in-kernel users.

I tested this change with test generic/402 on ext4/xfs/btrfs
and overlayfs, but not with nfsd.

Jeff, could you ack this change is good for nfsd as well?

Thanks,
Amir.

[1] https://lore.kernel.org/linux-fsdevel/20191111073000.2957-1-amir73il@gmail.com/

 fs/attr.c   | 5 +++++
 fs/utimes.c | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/attr.c b/fs/attr.c
index df28035aa23e..e8de5e636e66 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -268,8 +268,13 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de
 	attr->ia_ctime = now;
 	if (!(ia_valid & ATTR_ATIME_SET))
 		attr->ia_atime = now;
+	else
+		attr->ia_atime = timestamp_truncate(attr->ia_atime, inode);
 	if (!(ia_valid & ATTR_MTIME_SET))
 		attr->ia_mtime = now;
+	else
+		attr->ia_mtime = timestamp_truncate(attr->ia_mtime, inode);
+
 	if (ia_valid & ATTR_KILL_PRIV) {
 		error = security_inode_need_killpriv(dentry);
 		if (error < 0)
diff --git a/fs/utimes.c b/fs/utimes.c
index 1ba3f7883870..090739322463 100644
--- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -36,14 +36,14 @@ static int utimes_common(const struct path *path, struct timespec64 *times)
 		if (times[0].tv_nsec == UTIME_OMIT)
 			newattrs.ia_valid &= ~ATTR_ATIME;
 		else if (times[0].tv_nsec != UTIME_NOW) {
-			newattrs.ia_atime = timestamp_truncate(times[0], inode);
+			newattrs.ia_atime = times[0];
 			newattrs.ia_valid |= ATTR_ATIME_SET;
 		}
 
 		if (times[1].tv_nsec == UTIME_OMIT)
 			newattrs.ia_valid &= ~ATTR_MTIME;
 		else if (times[1].tv_nsec != UTIME_NOW) {
-			newattrs.ia_mtime = timestamp_truncate(times[1], inode);
+			newattrs.ia_mtime = times[1];
 			newattrs.ia_valid |= ATTR_MTIME_SET;
 		}
 		/*
-- 
2.17.1

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