From 41c9b1be335b5afc3b5fb71c5d16f9d5939cd13f Mon Sep 17 00:00:00 2001
From: Dave Jiang <dave.jiang@intel.com>
Date: Mon, 10 Sep 2018 16:18:29 -0700
Subject: [PATCH] device-dax: Add missing address_space_operations
Git-commit: 41c9b1be335b5afc3b5fb71c5d16f9d5939cd13f
Patch-mainline: v4.19-rc6
References: bsc#1107783

With address_space_operations missing for device dax, namely the
.set_page_dirty, we hit a kernel warning when running destructive
ndctl unit test: make TESTS=device-dax check

Warning: CPU: 3 PID: 7380 at fs/buffer.c:581 __set_page_dirty+0xb1/0xc0

Setting address_space_operations to noop_set_page_dirty and
noop_invalidatepage for device dax to prevent fallback to
__set_page_dirty_buffers() and block_invalidatepage() respectively.

Fixes: 2232c6382a ("device-dax: Enable page_mapping()")

Acked-by: Jeff Moyer <jmoyer@redhat.com>
Reported-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Jan Kara <jack@suse.cz>

---
 drivers/dax/device.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -542,6 +542,11 @@ static unsigned long dax_get_unmapped_ar
 	return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 }
 
+static const struct address_space_operations dev_dax_aops = {
+	.set_page_dirty		= noop_set_page_dirty,
+	.invalidatepage		= noop_invalidatepage,
+};
+
 static int dax_open(struct inode *inode, struct file *filp)
 {
 	struct dax_device *dax_dev = inode_dax(inode);
@@ -551,6 +556,7 @@ static int dax_open(struct inode *inode,
 	dev_dbg(&dev_dax->dev, "%s\n", __func__);
 	inode->i_mapping = __dax_inode->i_mapping;
 	inode->i_mapping->host = __dax_inode;
+	inode->i_mapping->a_ops = &dev_dax_aops;
 	filp->f_mapping = inode->i_mapping;
 	filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 	filp->private_data = dev_dax;