Without this patch all DM devices will default to BLK_MAX_SEGMENT_SIZE (65536) even if the underlying device(s) have a larger value -- this is due to blk_stack_limits() using min_not_zero() when stacking the max_segment_size limit. # cat /sys/block/sda/queue/max_segment_size 1073741824 # cat /sys/block/dm-0/queue/max_segment_size before patch: 65536 after patch: 1073741824 Reported-by: Lukasz Flis <l.flis@xxxxxxxxxxx> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx # v3.3+ --- block/blk-settings.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/block/blk-settings.c b/block/blk-settings.c index c50ecf0..29f28bb 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -143,6 +143,7 @@ void blk_set_stacking_limits(struct queue_limits *lim) /* Inherit limits from component devices */ lim->discard_zeroes_data = 1; lim->max_segments = USHRT_MAX; + lim->max_segment_size = UINT_MAX; lim->max_hw_sectors = UINT_MAX; lim->max_sectors = UINT_MAX; lim->max_write_same_sectors = UINT_MAX; -- 1.7.4.4 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
