[PATCH v5 6/6] xfs: disable map_sync for async flush

Pankaj Gupta
2019-04-10T04:11:23Z

Dont support 'MAP_SYNC' with non-DAX files and DAX files
with asynchronous dax_device. Virtio pmem provides
asynchronous host page cache flush mechanism. We don't
support 'MAP_SYNC' with virtio pmem and xfs.

Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
---
fs/xfs/xfs_file.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 1f2e2845eb76..0e59be018511 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1196,11 +1196,13 @@ xfs_file_mmap(
struct file *filp,
struct vm_area_struct *vma)
{
- /*
- * We don't support synchronous mappings for non-DAX files. At least
- * until someone comes with a sensible use case.
+ struct dax_device *dax_dev = xfs_find_daxdev_for_inode
+ (file_inode(filp));
+
+ /* We don't support synchronous mappings for non-DAX files and
+ * for DAX files if underneath dax_device is not synchronous.
*/
- if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC))
+ if (!daxdev_mapping_supported(vma, dax_dev))
return -EOPNOTSUPP;

file_accessed(filp);
--
2.20.1