generic: check fiemap SHARED flag on sync
The test case will check SHARED flag returned by fiemap ioctl on
reflinked files before and after sync.
Normally SHARED flag won't change just due to a normal sync
operation.
But btrfs doesn't handle SHARED flag well, and this time it won't
check any delayed extent tree(reverse extent searching tree)
modification, but only metadata already committed to disk.
So btrfs will not return correct SHARED flag on reflinked files if
there is no sync to commit all metadata.
This testcase will just check it.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>