[dm-devel] [PATCH 5/5] dax: always use _copy_mc_to_iter in dax_copy_to_iter

[Christoph Hellwig]

While using the MC-safe copy routines is rather pointless on a virtual device
like virtiofs, it also isn't harmful at all.  So just use _copy_mc_to_iter
unconditionally to simplify the code.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 drivers/dax/super.c | 10 ----------
 fs/fuse/virtio_fs.c |  1 -
 include/linux/dax.h |  1 -
 3 files changed, 12 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index ff676a07480c8..fe783234ca669 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -107,8 +107,6 @@ enum dax_device_flags {
 	DAXDEV_SYNC,
 	/* do not use uncached operations to write data */
 	DAXDEV_CACHED,
-	/* do not use mcsafe operations to read data */
-	DAXDEV_NOMCSAFE,
 };
 
 /**
@@ -171,8 +169,6 @@ size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
 	 * via access_ok() in vfs_red, so use the 'no check' version to bypass
 	 * the HARDENED_USERCOPY overhead.
 	 */
-	if (test_bit(DAXDEV_NOMCSAFE, &dax_dev->flags))
-		return _copy_to_iter(addr, bytes, i);
 	return _copy_mc_to_iter(addr, bytes, i);
 }
 
@@ -242,12 +238,6 @@ void set_dax_cached(struct dax_device *dax_dev)
 }
 EXPORT_SYMBOL_GPL(set_dax_cached);
 
-void set_dax_nomcsafe(struct dax_device *dax_dev)
-{
-	set_bit(DAXDEV_NOMCSAFE, &dax_dev->flags);
-}
-EXPORT_SYMBOL_GPL(set_dax_nomcsafe);
-
 bool dax_alive(struct dax_device *dax_dev)
 {
 	lockdep_assert_held(&dax_srcu);
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 754319ce2a29b..d9c20b148ac19 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -838,7 +838,6 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
 	if (IS_ERR(fs->dax_dev))
 		return PTR_ERR(fs->dax_dev);
 	set_dax_cached(fs->dax_dev);
-	set_dax_nomcsafe(fs->dax_dev);
 	return devm_add_action_or_reset(&vdev->dev, virtio_fs_cleanup_dax,
 					fs->dax_dev);
 }
diff --git a/include/linux/dax.h b/include/linux/dax.h
index d22cbf03d37d2..d267331bc37e7 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -90,7 +90,6 @@ static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
 #endif
 
 void set_dax_cached(struct dax_device *dax_dev);
-void set_dax_nomcsafe(struct dax_device *dax_dev);
 
 struct writeback_control;
 #if defined(CONFIG_BLOCK) && defined(CONFIG_FS_DAX)
-- 
2.30.2