Re: [PATCH 01/11] xfs: explicitly define inode timestamp range

[Allison Collins <allison.henderson@xxxxxxxxxx>]

On 8/26/20 3:05 PM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Formally define the inode timestamp ranges that existing filesystems
> support, and switch the vfs timetamp ranges to use it.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
Looks ok to me:
Reviewed-by: Allison Collins <allison.henderson@xxxxxxxxxx>

> ---
>   fs/xfs/libxfs/xfs_format.h |   22 ++++++++++++++++++++++
>   fs/xfs/xfs_super.c         |    4 ++--
>   2 files changed, 24 insertions(+), 2 deletions(-)
>
>
> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> index fe129fe16d5f..e57360a8fd16 100644
> --- a/fs/xfs/libxfs/xfs_format.h
> +++ b/fs/xfs/libxfs/xfs_format.h
> @@ -848,11 +848,33 @@ struct xfs_agfl {
>   	    ASSERT(xfs_daddr_to_agno(mp, d) == \
>   		   xfs_daddr_to_agno(mp, (d) + (len) - 1)))
>   
> +/*
> + * XFS Timestamps
> + * ==============
> + *
> + * Traditional ondisk inode timestamps consist of signed 32-bit counters for
> + * seconds and nanoseconds; time zero is the Unix epoch, Jan  1 00:00:00 UTC
> + * 1970, which means that the timestamp epoch is the same as the Unix epoch.
> + * Therefore, the ondisk min and max defined here can be used directly to
> + * constrain the incore timestamps on a Unix system.
> + */
>   typedef struct xfs_timestamp {
>   	__be32		t_sec;		/* timestamp seconds */
>   	__be32		t_nsec;		/* timestamp nanoseconds */
>   } xfs_timestamp_t;
>   
> +/*
> + * Smallest possible ondisk seconds value with traditional timestamps.  This
> + * corresponds exactly with the incore timestamp Dec 13 20:45:52 UTC 1901.
> + */
> +#define XFS_LEGACY_TIME_MIN	((int64_t)S32_MIN)
> +
> +/*
> + * Largest possible ondisk seconds value with traditional timestamps.  This
> + * corresponds exactly with the incore timestamp Jan 19 03:14:07 UTC 2038.
> + */
> +#define XFS_LEGACY_TIME_MAX	((int64_t)S32_MAX)
> +
>   /*
>    * On-disk inode structure.
>    *
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index c7ffcb57b586..b3b0e6154bf2 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1484,8 +1484,8 @@ xfs_fc_fill_super(
>   	sb->s_maxbytes = MAX_LFS_FILESIZE;
>   	sb->s_max_links = XFS_MAXLINK;
>   	sb->s_time_gran = 1;
> -	sb->s_time_min = S32_MIN;
> -	sb->s_time_max = S32_MAX;
> +	sb->s_time_min = XFS_LEGACY_TIME_MIN;
> +	sb->s_time_max = XFS_LEGACY_TIME_MAX;
>   	sb->s_iflags |= SB_I_CGROUPWB;
>   
>   	set_posix_acl_flag(sb);