diff mbox series

[RFC,PKS/PMEM,56/58] dax: Stray access protection for dax_direct_access()

Message ID 20201009195033.3208459-57-ira.weiny@intel.com
State New
Headers show
Series PMEM: Introduce stray write protection for PMEM | expand

Commit Message

Ira Weiny Oct. 9, 2020, 7:50 p.m. UTC 
From: Ira Weiny <ira.weiny@intel.com>

dax_direct_access() is a special case of accessing pmem via a page
offset and without a struct page.

Because the dax driver is well aware of the special protections it has
mapped memory with, call dev_access_[en|dis]able() directly instead of
the unnecessary overhead of trying to get a page to kmap.

Similar to kmap, we leverage existing functions, dax_read_[un]lock(),
because they are already required to surround the use of the memory
returned from dax_direct_access().

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

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index e84070b55463..0ddb3ee73e36 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -30,6 +30,7 @@  static DEFINE_SPINLOCK(dax_host_lock);
 
 int dax_read_lock(void)
 {
+	dev_access_enable(false);
 	return srcu_read_lock(&dax_srcu);
 }
 EXPORT_SYMBOL_GPL(dax_read_lock);
@@ -37,6 +38,7 @@  EXPORT_SYMBOL_GPL(dax_read_lock);
 void dax_read_unlock(int id)
 {
 	srcu_read_unlock(&dax_srcu, id);
+	dev_access_disable(false);
 }
 EXPORT_SYMBOL_GPL(dax_read_unlock);