[dm-devel] [RESEND PATCH] block: do not artificially constrain max_sectors for stacking drivers

[Mike Snitzer]

blk_set_stacking_limits is intended to allow stacking drivers to build
up the limits of the stacked device based on the underlying devices'
limits.  But defaulting 'max_sectors' to BLK_DEF_MAX_SECTORS (1024)
doesn't allow the stacking driver to inherit a max_sectors larger than
1024 -- due to blk_stack_limits' use of min_not_zero.

It is now clear that this artificial limit is getting in the way so
change blk_set_stacking_limits's max_sectors to UINT_MAX (which allows
stacking drivers like dm-multipath to inherit 'max_sectors' from the
underlying paths).

Reported-by: Vijay Chauhan <vijay.chauhan at netapp.com>
Tested-by: Vijay Chauhan <vijay.chauhan at netapp.com>
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
 block/blk-settings.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/block/blk-settings.c b/block/blk-settings.c
index d3234fc..565a678 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -143,8 +143,7 @@ void blk_set_stacking_limits(struct queue_limits *lim)
 	lim->discard_zeroes_data = 1;
 	lim->max_segments = USHRT_MAX;
 	lim->max_hw_sectors = UINT_MAX;
-
-	lim->max_sectors = BLK_DEF_MAX_SECTORS;
+	lim->max_sectors = UINT_MAX;
 }
 EXPORT_SYMBOL(blk_set_stacking_limits);
 
-- 
1.7.4.4