A 1.5 multiplier doesn't seem to be sufficient for XFS as seen in
mkosi CI. Let's increase it to 2 for XFS to hopefully get better
results.
/* Massage the size a bit because just going by actual data used in the sparse file isn't
* fool-proof. */
- fsz = round_up_size(fsz + (fsz / 2), context->grain_size);
+ uint64_t heuristic = streq(p->format, "xfs") ? fsz : fsz / 2;
+ fsz = round_up_size(fsz + heuristic, context->grain_size);
if (minimal_size_by_fs_name(p->format) != UINT64_MAX)
fsz = MAX(minimal_size_by_fs_name(p->format), fsz);