block: fix the DISCARD request merge
commit 69840466086d2248898020a08dda52732686c4e6 upstream. There are two cases when handle DISCARD merge. If max_discard_segments == 1, the bios/requests need to be contiguous to merge. If max_discard_segments > 1, it takes every bio as a range and different range needn't to be contiguous. But now, attempt_merge screws this up. It always consider contiguity for DISCARD for the case max_discard_segments > 1 and cannot merge contiguous DISCARD for the case max_discard_segments == 1, because rq_attempt_discard_merge always returns false in this case. This patch fixes both of the two cases above. Reviewed-by: NChristoph Hellwig <hch@lst.de> Reviewed-by: NMing Lei <ming.lei@redhat.com> Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com> Signed-off-by: NJens Axboe <axboe@kernel.dk> Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com> Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
Showing
想要评论请 注册 或 登录