[PATCH v2 0/2] Add two SEEK_DATA/SEEK_HOLE tests

[Jeff Liu]

Hello,

This patch series add two tests to verify SEEK_DATA/SEEK_HOLE feature works fine on supported
file systems(Btrfs/OCFS2) and XFS which is in progress.


V2 changes in seek_sanity_tester:
* change test index number from 276 to 279 since I observed that 276~278 have already been used by other tests.

v2 changes in seek_copy_tester:
* change test index number to 280 accordingly.
* s/do_pwrite/full_pwrite/
* add more debug info when writing ZERO byte to dest file.
* fix a bug at create_data_and_holes() to avoid write more bytes exceeding total file size, thank Mark. :)
* mark all function as static, maybe it's better to consolidate some common functions at sanity check and copy tester to a lib file in future.

Thanks,
-Jeff