tmpfs: add support for multigrain timestamps

Enable multigrain timestamps, which should ensure that there is an
apparent change to the timestamp whenever it has been written after
being actively observed via getattr.

tmpfs only requires the FS_MGTIME flag.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Message-Id: <20230807-mgctime-v7-10-d1dec143a704@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index 142ead70e8c1eeba71ed28ab09edbb81a1e716b1..98cc4be7a8a89793a7b9bc08010ff9eb1a21a6bf 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4220,7 +4220,7 @@ static struct file_system_type shmem_fs_type = {
 #endif
        .kill_sb        = kill_litter_super,
 #ifdef CONFIG_SHMEM
-       .fs_flags       = FS_USERNS_MOUNT | FS_ALLOW_IDMAP,
+       .fs_flags       = FS_USERNS_MOUNT | FS_ALLOW_IDMAP | FS_MGTIME,
 #else
        .fs_flags       = FS_USERNS_MOUNT,
 #endif