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From: Ira Weiny <ira.weiny@intel.com>
Date: Sun, 24 Mar 2024 16:18:24 -0700
Subject: [PATCH 21/26] dax/region: Prevent range mapping allocation on
 sparse regions
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Message-Id: <20240324-dcd-type2-upstream-v1-21-b7b00d623625@intel.com>
References: <20240324-dcd-type2-upstream-v1-0-b7b00d623625@intel.com>
In-Reply-To: <20240324-dcd-type2-upstream-v1-0-b7b00d623625@intel.com>
To: Dave Jiang <dave.jiang@intel.com>, Fan Ni <fan.ni@samsung.com>, 
 Jonathan Cameron <Jonathan.Cameron@huawei.com>, 
 Navneet Singh <navneet.singh@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>, 
 Davidlohr Bueso <dave@stgolabs.net>, 
 Alison Schofield <alison.schofield@intel.com>, 
 Vishal Verma <vishal.l.verma@intel.com>, Ira Weiny <ira.weiny@intel.com>, 
 linux-btrfs@vger.kernel.org, linux-cxl@vger.kernel.org, 
 linux-kernel@vger.kernel.org

Sparse regions are not fully populated with memory and this complicates
range mapping of dax devices on those regions.  There is no use case for
range mapping on sparse regions.

Avoid the complication by prevent range mapping of dax devices on sparse
regions.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
 drivers/dax/bus.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index bab19fc578d0..56dddaceeccb 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -1452,6 +1452,8 @@ static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
 		return 0;
 	if (a == &dev_attr_mapping.attr && is_static(dax_region))
 		return 0;
+	if (a == &dev_attr_mapping.attr && is_sparse(dax_region))
+		return 0;
 	if ((a == &dev_attr_align.attr ||
 	     a == &dev_attr_size.attr) && is_static(dax_region))
 		return 0444;

-- 
2.44.0