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.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 mm/shmem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 654d9a585820..b6019c905058 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4264,7 +4264,7 @@ 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

-- 
2.41.0

On Tue 25-07-23 10:58:17, Jeff Layton wrote:
> 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.
> 
> Signed-off-by: Jeff Layton <jlayton@kernel.org>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  mm/shmem.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 654d9a585820..b6019c905058 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -4264,7 +4264,7 @@ 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
> 
> -- 
> 2.41.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR