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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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