dm linear: add DAX support

Change dm-linear to implement direct_access function,
linear_direct_access(), which maps sector and calls direct_access
function of its physical target device.

Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 05c35aacb3aa..6d35dd4e9efb 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -141,9 +141,27 @@ static int linear_iterate_devices(struct dm_target *ti,
         return fn(ti, lc->dev, lc->start, ti->len, data);
 }
 
+static long linear_direct_access(struct dm_target *ti, sector_t sector,
+                                 void __pmem **kaddr, pfn_t *pfn, long size)
+{
+        struct linear_c *lc = ti->private;
+        struct block_device *bdev = lc->dev->bdev;
+        struct blk_dax_ctl dax = {
+                .sector = linear_map_sector(ti, sector),
+                .size = size,
+        };
+        long ret;
+
+        ret = bdev_direct_access(bdev, &dax);
+        *kaddr = dax.addr;
+        *pfn = dax.pfn;
+
+        return ret;
+}
+
 static struct target_type linear_target = {
         .name   = "linear",
-        .version = {1, 2, 1},
+        .version = {1, 3, 0},
         .module = THIS_MODULE,
         .ctr    = linear_ctr,
         .dtr    = linear_dtr,
@@ -151,6 +169,7 @@ static struct target_type linear_target = {
         .status = linear_status,
         .prepare_ioctl = linear_prepare_ioctl,
         .iterate_devices = linear_iterate_devices,
+        .direct_access = linear_direct_access,
 };
 
 int __init dm_linear_init(void)