On Wed 09-01-19 19:26:05, Pankaj Gupta wrote: > Virtio pmem provides asynchronous host page cache flush > mechanism. We don't support 'MAP_SYNC' with virtio pmem > and ext4. > > Signed-off-by: Pankaj Gupta <pagupta@xxxxxxxxxx> ... > @@ -371,6 +373,13 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma) > if (!IS_DAX(file_inode(file)) && (vma->vm_flags & VM_SYNC)) > return -EOPNOTSUPP; > > + /* We don't support synchronous mappings with guest direct access > + * and virtio based host page cache flush mechanism. > + */ > + if (IS_DAX(file_inode(file)) && virtio_pmem_host_cache_enabled(dax_dev) > + && (vma->vm_flags & VM_SYNC)) > + return -EOPNOTSUPP; > + Shouldn't there rather be some generic way of doing this? Having virtio_pmem_host_cache_enabled() check in filesystem code just looks like filesystem sniffing into details is should not care about... Maybe just naming this (or having a wrapper) dax_dev_map_sync_supported()? Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
