Re: [PATCH v6 3/3] xfs: add support for FALLOC_FL_WRITE_ZEROES

On Thu, Jun 18, 2026 at 11:22:45AM +0800, Zhang Yi wrote:
> 1) if the two blocks straddling the boundaries have not yet been allocated,
>    or allocated as unwritten, we should round outward the allocation range
>    and zero out all allocated blocks, including those two boundary blocks.
> 2) if the blocks at the boundaries are already in the written state — which
>    can occur when we call FALLOC_FL_WRITE_ZEROES within the file size. We
>    should be careful here: we should only zero the ranges [offset, offset_ru)
>    and [end_rd, end) for the boundary blocks, leaving the already-written
>    portions of the boundary blocks intact.
> 
> Thoughs?

Yes.

> Regarding the second point, the current ext4 implementation has an issue —
> it zeroes out the entire boundary blocks. I overlooked this previously, and
> I appreciate you pointing it out.

Which means we're missing test coverage for this as well..