Set max_discard_segments to USHRT_MAX in blk_set_stacking_limits() so that blk_stack_limits() can stack up this limit for stacked devices. before: $ cat /sys/block/nvme0n1/queue/max_discard_segments 256 $ cat /sys/block/dm-0/queue/max_discard_segments 1 after: $ cat /sys/block/nvme0n1/queue/max_discard_segments 256 $ cat /sys/block/dm-0/queue/max_discard_segments 256 Fixes: 1e739730c5b9e ("block: optionally merge discontiguous discard bios into a single request") Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> --- block/blk-settings.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/blk-settings.c b/block/blk-settings.c index d1de71124656..24fff4a3d08a 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -128,7 +128,7 @@ void blk_set_stacking_limits(struct queue_limits *lim) /* Inherit limits from component devices */ lim->max_segments = USHRT_MAX; - lim->max_discard_segments = 1; + lim->max_discard_segments = USHRT_MAX; lim->max_hw_sectors = UINT_MAX; lim->max_segment_size = UINT_MAX; lim->max_sectors = UINT_MAX; -- 2.18.0