From 0b4c6ced6ee1ee3f6ba4442973ed1901bae7da1e Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Mon, 9 Oct 2017 15:11:13 +0200
Subject: [KERNEL] version check to support pointer to backing_dev_info in
 request_queue

This changed in 4.11, see
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=dc3b17cc8bf21307c7e076e7c778d5db756f7871
---
 src/kernel/blk.c | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'src/kernel')

diff --git a/src/kernel/blk.c b/src/kernel/blk.c
index 7a2b6e9..5dec195 100644
--- a/src/kernel/blk.c
+++ b/src/kernel/blk.c
@@ -174,7 +174,13 @@ int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, u
 			// Forget all alt servers on explicit connect, set first al server to initial server
 			memset(dev->alt_servers, 0, sizeof(dev->alt_servers[0])*NUMBER_SERVERS);
 			memcpy(dev->alt_servers, &dev->initial_server, sizeof(dev->alt_servers[0]));
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
+			if (blk_queue->backing_dev_info != NULL) {
+				blk_queue->backing_dev_info->ra_pages = (msg->read_ahead_kb * 1024) / PAGE_SIZE;
+			}
+#else
 			blk_queue->backing_dev_info.ra_pages = (msg->read_ahead_kb * 1024) / PAGE_SIZE;
+#endif
 			if (dnbd3_net_connect(dev) == 0)
 			{
 				result = 0;
-- 
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