On 10/30/19 9:29 PM, Darrick J. Wong wrote: > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > Currently, if the loop device receives a WRITE_ZEROES request, it asks > the underlying filesystem to punch out the range. This behavior is > correct if unmapping is allowed. However, a NOUNMAP request means that > the caller doesn't want us to free the storage backing the range, so > punching out the range is incorrect behavior. > > To satisfy a NOUNMAP | WRITE_ZEROES request, loop should ask the > underlying filesystem to FALLOC_FL_ZERO_RANGE, which is (according to > the fallocate documentation) required to ensure that the entire range is > backed by real storage, which suffices for our purposes. Applied, thanks Darrick. -- Jens Axboe
