linux-kernel - [PATCH] fs: grab current_time() in setattr_copy_mgtime() when ATTR

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Message-Id: <20241009-mgtime-v1-1-383b9e0481b5@kernel.org>
Date: Wed, 09 Oct 2024 12:26:32 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Alexander Viro <viro@...iv.linux.org.uk>, 
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Jeff Layton <jlayton@...nel.org>
Subject: [PATCH] fs: grab current_time() in setattr_copy_mgtime() when
 ATTR_CTIME is unset

With support of delegated timestamps, nfsd can issue a setattr that sets
the atime, but not the ctime. Ensure that when the ctime isn't set that
"now" is set to the current coarse-grained time.

Reported-by: Jan Kara <jack@...e.cz>
Closes: https://lore.kernel.org/linux-fsdevel/20241009153022.5uyp6aku2kcfeexp@quack3/
Fixes: d8d11298e8a1 ("fs: handle delegated timestamps in setattr_copy_mgtime")
Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
A fix for bug that Jan reported. Christian, it may be best to fold this
into d8d11298e8a1.
---
 fs/attr.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/attr.c b/fs/attr.c
index c614b954bda5244cc20ee82a98a8e68845f23bd7..9caf63d20d03e86c535e9c8c91d49c2a34d34b7a 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -298,6 +298,7 @@ static void setattr_copy_mgtime(struct inode *inode, const struct iattr *attr)
 	} else {
 		/* If ATTR_CTIME isn't set, then ATTR_MTIME shouldn't be either. */
 		WARN_ON_ONCE(ia_valid & ATTR_MTIME);
+		now = current_time(inode);
 	}
 
 	if (ia_valid & ATTR_ATIME_SET)

---
base-commit: 109aff7a3b294d9dc0f49d33fc6746e8d27e46f6
change-id: 20241009-mgtime-f672852d67cc

Best regards,
-- 
Jeff Layton <jlayton@...nel.org>