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.f...@cyfronet.pl>
Signed-off-by: Mike Snitzer <snit...@redhat.com>
Cc: sta...@vger.kernel.org # 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
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