[RFC PATCH 10/15] drivers/dax: Expand lock scope to cover the use of addresses

ira.weiny
2020-07-14T07:04:22Z

From: Ira Weiny <ira.weiny@intel.com>

The addition of PKS protection to dax read lock/unlock will require that
the address returned by dax_direct_access() be protected by this lock.

While not technically necessary for this series, this corrects the
locking by ensuring that the use of kaddr and end_kaddr are covered by
the dax read lock/unlock.

Change the lock scope to cover the kaddr and end_kaddr use.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
drivers/dax/super.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 8e32345be0f7..021739768093 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -103,11 +103,11 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
id = dax_read_lock();
len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn);
- dax_read_unlock(id);

if (len < 1 || len2 < 1) {
pr_debug("%s: error: dax access failed (%ld)\n",
bdevname(bdev, buf), len < 1 ? len : len2);
+ dax_read_unlock(id);
return false;
}

@@ -137,6 +137,7 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
put_dev_pagemap(end_pgmap);

}
+ dax_read_unlock(id);

if (!dax_enabled) {
pr_debug("%s: error: dax support not enabled\n",