[LTP] [PATCH v2 1/2] syscalls/sync_file_range: add partial file sync test-case

[Sumit Garg]

On Tue, 5 Mar 2019 at 19:49, Cyril Hrubis <chrubis@suse.cz> wrote:
>
> Hi!
> > +static void verify_sync_partial_file(void)
> > +{
> > +     int fd;
> > +     unsigned long written;
> > +
> > +     fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
> > +
> > +     tst_dev_bytes_written(tst_device->dev);
> > +
> > +     tst_fill_fd(fd, 0xff, TST_MB, FILE_SIZE_MB);
> > +
> > +     TEST(sync_file_range(fd, FILE_SIZE/4, FILE_SIZE/2,
> > +                          SYNC_FILE_RANGE_WAIT_BEFORE |
> > +                          SYNC_FILE_RANGE_WRITE |
> > +                          SYNC_FILE_RANGE_WAIT_AFTER));
> > +
> > +     if (TST_RET)
> > +             tst_brk(TFAIL | TTERRNO, "sync_file_range() failed");
> > +
> > +     written = tst_dev_bytes_written(tst_device->dev);
> > +
> > +     SAFE_CLOSE(fd);
> > +
> > +     if (written >= FILE_SIZE/2)
> > +             tst_res(TPASS, "Test file range synced to device");
> > +     else
> > +             tst_res(TFAIL, "Synced %li, expected %i", written,
> > +                     FILE_SIZE/2);
> > +}
>
>
> Looking at this the function is nearly the same as the other one, I
> guess that we may as well define the function as:
>
> static void verify_sync_file_range(off64_t off, off64_t size, char byte)
> {
>         ...
> }
>

Yeah it could be made common. But we may not be able to reuse it for
third case you mentioned below.

> Also I'm not sure I was clear enough, but I was suggesting to check for
> upper bound for the synced size as well, which is why I suggested to do
> full write, sync only part of it, then check that the size was within
> bounds, i.e. >= size and  <= size + epsilon.
>

Do you see any value add of upper bound check? AFAIK, device writes
continue in back-end and we might not be sure about appropriate value
for "epsilon".

> I guess that we can even extend this to call the sync over a range that
> has been only partially written, but for that we would have to be
> careful and make sure all the data has been either synced at the end of
> the test function or use a different file for each test.
>

I think using different file for each case looks more appropriate.

-Sumit

> --
> Cyril Hrubis
> chrubis@suse.cz