From: Ilya Dryomov <idryomov@gmail.com>
Date: Thu, 21 Dec 2017 15:35:11 +0100
Subject: rbd: set max_segments to USHRT_MAX
Git-commit: 21acdf45f4958135940f0b4767185cf911d4b010
Patch-mainline: v4.15-rc8
References: bsc#1078861

Commit d3834fefcfe5 ("rbd: bump queue_max_segments") bumped
max_segments (unsigned short) to max_hw_sectors (unsigned int).
max_hw_sectors is set to the number of 512-byte sectors in an object
and overflows unsigned short for 32M (largest possible) objects, making
the block layer resort to handing us single segment (i.e. single page
or even smaller) bios in that case.

Cc: stable@vger.kernel.org
Fixes: d3834fefcfe5 ("rbd: bump queue_max_segments")
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Acked-by: Lee Duncan <lduncan@suse.com>
---
 drivers/block/rbd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index aacae6f7163e..cc93522a6d41 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -4387,7 +4387,7 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
 	segment_size = rbd_obj_bytes(&rbd_dev->header);
 	blk_queue_max_hw_sectors(q, segment_size / SECTOR_SIZE);
 	q->limits.max_sectors = queue_max_hw_sectors(q);
-	blk_queue_max_segments(q, segment_size / SECTOR_SIZE);
+	blk_queue_max_segments(q, USHRT_MAX);
 	blk_queue_max_segment_size(q, segment_size);
 	blk_queue_io_min(q, segment_size);
 	blk_queue_io_opt(q, segment_size);