On Fri, Jan 09, 2026 at 01:08:33PM +0100, Fiona Ebner wrote: > This fixes io-test 179 with qcow2. Otherwise, there would be more 'data' > sectors. > > Signed-off-by: Fiona Ebner <[email protected]> > --- > > Not sure if we should even attempt this without considering > detect-zeroes. While it does keep 179 working, it is a change in > behavior, since it could turn previously data sectors (with zeroes) > into zero sectors when they are part of the head or tail of a zero > write. > > Would it even be tolerable from a performance perspective?
179 compares qemu-img map output and this makes changes to allocation status fragile. In a case like this I would either adjust the test case and regenerate the output, or if the output variance is now unavoidable then a more sophisticated filter function is needed. I'd avoid buffer_is_zero() in bdrv_co_do_zero_pwritev() since it eats CPU cycles. Stefan
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