[Qemu-devel] [PATCH v4 5/5] xfs: disable map_sync for async flush

[Pankaj Gupta]

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 <address@hidden>
---
 fs/xfs/xfs_file.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 1f2e2845eb76..dced2eb8c91a 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1203,6 +1203,14 @@ xfs_file_mmap(
        if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC))
                return -EOPNOTSUPP;
 
+       /* We don't support synchronous mappings with DAX files if
+        * dax_device is not synchronous.
+        */
+       if (IS_DAX(file_inode(filp)) && !dax_synchronous(
+               xfs_find_daxdev_for_inode(file_inode(filp))) &&
+                                       (vma->vm_flags & VM_SYNC))
+               return -EOPNOTSUPP;
+
        file_accessed(filp);
        vma->vm_ops = &xfs_file_vm_ops;
        if (IS_DAX(file_inode(filp)))
-- 
2.20.1