[LTP] [PATCH RFC] sync_file_range02: remove the toplimit of write back

[Jan Stancek]

----- Original Message -----
> " The test's assumptions are fundamentally false; it thinks it can look
> at IO counters (tst_dev_bytes_written) for a disk before and after a
> system call, and attribute all of the IO seen to the system call that
> was made - this isn't necessarily correct. Other processes may generate
> IO in the background.

We create our own block device, so there shouldn't be other processes
writing to it.

> ext4 defers a lot of IO on a freshly made filesystem to the kernel -
> for example it will initialize the journal and inode tables after the
> mount

Journal was my guess as well.

> Let's remove the toplimit of write back, and think as long as we synced
> at least the expected amount, the test passes. The +10% limit seems
> arbitrary.

I think this is reasonable approach until we find better way
to measure what was synced.

Acked-by: Jan Stancek <jstancek@redhat.com>