On Fri, Feb 24, 2017 at 05:40:59PM -0800, Deepa Dinamani wrote:
> Add fields to the superblock to track the min and max
> timestamps supported by filesystems.
>
> Initially, when a superblock is allocated, initialize
> it to the max and min values the fields can hold.
> Individual filesystems override these to match their
> actual limits.
>
> Pseudo filesystems are assumed to always support the
> min and max allowable values for the fields.
>
> Note that the time ranges are saved in type time64_t
> rather than time_t.
> This is required because if we save ranges in time_t
> then we would not be able to save timestamp ranges
> for files that support timestamps beyond y2038.
>
> Signed-off-by: Deepa Dinamani <deepa.kernel@xxxxxxxxx>
> ---
> fs/super.c | 2 ++
> include/linux/fs.h | 3 +++
> include/linux/time64.h | 2 ++
> 3 files changed, 7 insertions(+)
>
> diff --git a/fs/super.c b/fs/super.c
> index b8b6a08..f9c2241 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -247,6 +247,8 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
> s->s_maxbytes = MAX_NON_LFS;
> s->s_op = &default_op;
> s->s_time_gran = 1000000000;
> + s->s_time_min = TIME64_MIN;
> + s->s_time_max = TIME64_MAX;
Just out of curiosity, does this enable 64-bit timestamps for everything
by default? I see that ext4 later sets its own values in fill_super;
what about things like XFS that really only have 32-bit seconds fields?
--D
> s->cleancache_poolid = CLEANCACHE_NO_POOL;
>
> s->s_shrink.seeks = DEFAULT_SEEKS;
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index de8ed0b..ef55dfb 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1337,6 +1337,9 @@ struct super_block {
> /* Granularity of c/m/atime in ns.
> Cannot be worse than a second */
> u32 s_time_gran;
> + /* Time limits for c/m/atime in seconds. */
> + time64_t s_time_min;
> + time64_t s_time_max;
>
> /*
> * The next field is for VFS *only*. No filesystems have any business
> diff --git a/include/linux/time64.h b/include/linux/time64.h
> index 980c71b..25433b18 100644
> --- a/include/linux/time64.h
> +++ b/include/linux/time64.h
> @@ -38,6 +38,8 @@ struct itimerspec64 {
>
> /* Located here for timespec[64]_valid_strict */
> #define TIME64_MAX ((s64)~((u64)1 << 63))
> +#define TIME64_MIN (-TIME64_MAX - 1)
> +
> #define KTIME_MAX ((s64)~((u64)1 << 63))
> #define KTIME_SEC_MAX (KTIME_MAX / NSEC_PER_SEC)
>
> --
> 2.7.4
>
