[LTP] [PATCH v2 0/5] Tests for readahead() and fadvise() on overlayfs

[Amir Goldstein]

On Mon, Oct 8, 2018 at 2:26 PM Amir Goldstein <amir73il@gmail.com> wrote:
>
> On Mon, Oct 8, 2018 at 10:11 AM Jan Stancek <jstancek@redhat.com> wrote:
> >
> >
> >
> > ----- Original Message -----
> > > Cyril,
> > >
> > > The following series adds test covergae for readahead() syscall
> > > over overlayfs file and adds test coverage for a specific
> > > posix_fadvise() syscall advice (POSIX_FADV_WILLNEED).
> > >
> > > So far, the posix_fadvise syscall tests in LTP only test for error
> > > conditions, but not functionality.
> > >
> > > The functionality of the advice POSIX_FADV_WILLNEED is indentical
> > > to readahead() and since kernel commit 3d8f7615319b ("vfs: implement
> > > readahead(2) using POSIX_FADV_WILLNEED"), the implementations are
> > > also bound together.
> > >
> > > To add test coverage of the advice POSIX_FADV_WILLNEED, I decided not
> > > to duplicate the readahead() functional test and add test cases to
> > > readahead02 that use the POSIX_FADV_WILLNEED implementation.
> > >
> > > Thanks,
> > > Amir.
> > >
> > > Changes since v1:
> > > - Fix bugs in loop invocation of test (i.e. -i 2)
> > > - Address review comments from Jan Stancek
> > > - Make cached_max a global maximum over all test cases
> > > - Improve reliability of overlayfs readahead test case failure
> >
> > Looks good to me.
> >
> > When you say "This is the only system configuration supported by the posix_fadvise tests",
> > are you talking about glibc?
> >
>
> I was trying to mimic the check in posix_fadvise tests:
>
>         /* Check this system has fadvise64 system which is used
>            in posix_fadvise. */
>         if ((_FILE_OFFSET_BITS != 64) && (__NR_fadvise64 == 0)) {
>                 tst_resm(TWARN,
>                          "This test can only run on kernels that implements ");
>                 tst_resm(TWARN, "fadvise64 which is used from posix_fadvise");
>                 exit(0);
>         }
>
> If my understanding of man posix_fadvise(2) is correct, this wants to make sure
> that the glibc wrapper posix_fadvise calls the syscall fadvise64 and not some
> architecture specific syscall (e.g. arm_fadvise64_64).
>
> I am not really sure why that matters to those tests at all.
> and it's probably better just return TCONF if the call fails with ENOSYS?
> If someone has ideas, let me know.
>

FYI, I removed the build time checks from my test and added runtime checks
for both readahead and posix_fadvise kernel support:
https://github.com/amir73il/ltp/commits/overlayfs-devel

I will post v3 tomorrow.

Thanks,
Amir.