Commits
Martin K. Petersen committed e461338b6cd
sd: tweak discard heuristics to work around QEMU SCSI issue 7985090aa020 changed the discard heuristics to give preference to the WRITE SAME commands that (unlike UNMAP) guarantee deterministic results. Ming Lei discovered that QEMU SCSI's WRITE SAME implementation internally relied on limits that were only communicated for the UNMAP case. And therefore discard commands backed by WRITE SAME would fail. Tweak the heuristics so we still pick UNMAP in the LBPRZ=0 case and only prefer the WRITE SAME variants if the device has the LBPRZ flag set. Reported-by: Ming Lei <ming.lei@canonical.com> Tested-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de>