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SubjectRe: [PATCH 05/20] utimes: Clamp the timestamps before update
On Mon, Jul 29, 2019 at 06:49:09PM -0700, Deepa Dinamani wrote:
> POSIX is ambiguous on the behavior of timestamps for
> futimens, utimensat and utimes. Whether to return an
> error or silently clamp a timestamp beyond the range
> supported by the underlying filesystems is not clear.
>
> POSIX.1 section for futimens, utimensat and utimes says:
> (http://pubs.opengroup.org/onlinepubs/9699919799/functions/futimens.html)
>
> The file's relevant timestamp shall be set to the greatest
> value supported by the file system that is not greater
> than the specified time.
>
> If the tv_nsec field of a timespec structure has the special
> value UTIME_NOW, the file's relevant timestamp shall be set
> to the greatest value supported by the file system that is
> not greater than the current time.
>
> [EINVAL]
> A new file timestamp would be a value whose tv_sec
> component is not a value supported by the file system.
>
> The patch chooses to clamp the timestamps according to the
> filesystem timestamp ranges and does not return an error.
> This is in line with the behavior of utime syscall also
> since the POSIX page(http://pubs.opengroup.org/onlinepubs/009695399/functions/utime.html)
> for utime does not mention returning an error or clamping like above.
>
> Same for utimes http://pubs.opengroup.org/onlinepubs/009695399/functions/utimes.html
>
> Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
> ---
> fs/utimes.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/fs/utimes.c b/fs/utimes.c
> index 350c9c16ace1..4c1a2ce90bbc 100644
> --- a/fs/utimes.c
> +++ b/fs/utimes.c
> @@ -21,6 +21,7 @@ static int utimes_common(const struct path *path, struct timespec64 *times)
> int error;
> struct iattr newattrs;
> struct inode *inode = path->dentry->d_inode;
> + struct super_block *sb = inode->i_sb;
> struct inode *delegated_inode = NULL;
>
> error = mnt_want_write(path->mnt);
> @@ -36,16 +37,24 @@ static int utimes_common(const struct path *path, struct timespec64 *times)
> if (times[0].tv_nsec == UTIME_OMIT)
> newattrs.ia_valid &= ~ATTR_ATIME;
> else if (times[0].tv_nsec != UTIME_NOW) {
> - newattrs.ia_atime.tv_sec = times[0].tv_sec;
> - newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
> + newattrs.ia_atime.tv_sec =
> + clamp(times[0].tv_sec, sb->s_time_min, sb->s_time_max);
> + if (times[0].tv_sec == sb->s_time_max || times[0].tv_sec == sb->s_time_min)
> + newattrs.ia_atime.tv_nsec = 0;
> + else
> + newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
> newattrs.ia_valid |= ATTR_ATIME_SET;
> }
>
> if (times[1].tv_nsec == UTIME_OMIT)
> newattrs.ia_valid &= ~ATTR_MTIME;
> else if (times[1].tv_nsec != UTIME_NOW) {
> - newattrs.ia_mtime.tv_sec = times[1].tv_sec;
> - newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
> + newattrs.ia_mtime.tv_sec =
> + clamp(times[1].tv_sec, sb->s_time_min, sb->s_time_max);
> + if (times[1].tv_sec >= sb->s_time_max || times[1].tv_sec == sb->s_time_min)

Line length.

Also, didn't you just introduce a function to clamp tv_sec and fix
granularity? Why not just use it here? I think this is the third time
I've seen this open-coded logic.

--D

> + newattrs.ia_mtime.tv_nsec = 0;
> + else
> + newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
> newattrs.ia_valid |= ATTR_MTIME_SET;
> }
> /*
> --
> 2.17.1
>

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