From: Josef Bacik <jbacik@fb.com>
Date: Wed, 23 May 2018 13:35:59 -0400
Subject: [PATCH] nbd: set discard granularity properly
Git-commit: 6df133a1495f8c497d0f53005296ef5421752620
Patch-mainline: v4.18-rc1
References: bsc#1104967,FATE#325924

For some reason we had discard granularity set to 512 always even when
discards were disabled.  Fix this by having the default be 0, and then
if we turn it on set the discard granularity to the blocksize.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 drivers/block/nbd.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 1147e4680c80..bdfbb2a7018c 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -236,6 +236,10 @@ static void nbd_size_update(struct nbd_device *nbd)
 	struct nbd_config *config = nbd->config;
 	struct block_device *bdev = bdget_disk(nbd->disk, 0);
 
+	if (config->flags & NBD_FLAG_SEND_TRIM) {
+		nbd->disk->queue->limits.discard_granularity = config->blksize;
+		blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
+	}
 	blk_queue_logical_block_size(nbd->disk->queue, config->blksize);
 	blk_queue_physical_block_size(nbd->disk->queue, config->blksize);
 	set_capacity(nbd->disk, config->bytesize >> 9);
@@ -1050,6 +1054,8 @@ static void nbd_config_put(struct nbd_device *nbd)
 		nbd->config = NULL;
 
 		nbd->tag_set.timeout = 0;
+		nbd->disk->queue->limits.discard_granularity = 0;
+		blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
 		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, nbd->disk->queue);
 
 		mutex_unlock(&nbd->config_lock);
@@ -1502,8 +1508,8 @@ static int nbd_dev_add(int index)
 	 */
 	blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
 	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, disk->queue);
-	disk->queue->limits.discard_granularity = 512;
-	blk_queue_max_discard_sectors(disk->queue, UINT_MAX);
+	disk->queue->limits.discard_granularity = 0;
+	blk_queue_max_discard_sectors(disk->queue, 0);
 	blk_queue_max_segment_size(disk->queue, UINT_MAX);
 	blk_queue_max_segments(disk->queue, USHRT_MAX);
 	blk_queue_max_hw_sectors(disk->queue, 65536);
-- 
2.16.4