From: Mike Snitzer <snitzer@redhat.com>
Date: Fri, 20 Jul 2018 18:57:38 +0000 (-0400)
Subject: block: allow max_discard_segments to be stacked
X-Git-Tag: v4.14.72~140
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=030f2ad6ce16f3c49e4d9c65a4cd36f477f8e7b9;p=platform%2Fkernel%2Flinux-exynos.git

block: allow max_discard_segments to be stacked

[ Upstream commit 42c9cdfe1e11e083dceb0f0c4977b758cf7403b9 ]

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")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 8559e95..474b0b9 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;