[PATCH v9 4/7] dm: enable synchronous dax

Pankaj Gupta
2019-05-14T14:57:48Z

This patch sets dax device 'DAXDEV_SYNC' flag if all the target
devices of device mapper support synchrononous DAX. If device
mapper consists of both synchronous and asynchronous dax devices,
we don't set 'DAXDEV_SYNC' flag.

Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
---
drivers/md/dm-table.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index cde3b49b2a91..1cce626ff576 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -886,10 +886,17 @@ static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
return bdev_dax_supported(dev->bdev, PAGE_SIZE);
}

+static int device_synchronous(struct dm_target *ti, struct dm_dev *dev,
+ sector_t start, sector_t len, void *data)
+{
+ return dax_synchronous(dev->dax_dev);
+}
+
static bool dm_table_supports_dax(struct dm_table *t)
{
struct dm_target *ti;
unsigned i;
+ bool dax_sync = true;

/* Ensure that all targets support DAX. */
for (i = 0; i < dm_table_get_num_targets(t); i++) {
@@ -901,7 +908,14 @@ static bool dm_table_supports_dax(struct dm_table *t)
if (!ti->type->iterate_devices ||
!ti->type->iterate_devices(ti, device_supports_dax, NULL))
return false;
+
+ /* Check devices support synchronous DAX */
+ if (dax_sync &&
+ !ti->type->iterate_devices(ti, device_synchronous, NULL))
+ dax_sync = false;
}
+ if (dax_sync)
+ set_dax_synchronous(t->md->dax_dev);

return true;
}
--
2.20.1