On 08/10/14 15:55, Pádraig Brady wrote: > Subject: [PATCH 2/4] cp: avoid speculative preallocation with --sparse=always > > With --sparse=always use fallocate(...PUNCH_HOLE...) to > avoid any permanent allocation due to speculative > preallocation employed by file systems such as XFS.
For the record, I was wondering if we should apply the same punch_hole() processing to dd conv=sparse ? I'm 60:40 against as the implementation is documented to skip existing data in the output for NULs in the input. If one really cares about minimizing allocation after a dd copy, one can call `fallocate --dig-holes`, albeit with repeated processing of the non holes. cheers, Pádraig.
