Re: [Qemu-devel] [PATCH v6 5/6] ext4: disable map_sync for async flush

[Jan Kara]

On Tue 23-04-19 13:36:11, Pankaj Gupta wrote:
> 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 ext4.
> 
> Signed-off-by: Pankaj Gupta <address@hidden>

The patch looks good to me. You can add:

Reviewed-by: Jan Kara <address@hidden>

                                                                Honza


> ---
>  fs/ext4/file.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 69d65d49837b..4b2ccaf1932e 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -360,15 +360,16 @@ static const struct vm_operations_struct 
> ext4_file_vm_ops = {
>  static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
>  {
>       struct inode *inode = file->f_mapping->host;
> +     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> +     struct dax_device *dax_dev = sbi->s_daxdev;
>  
> -     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
> +     if (unlikely(ext4_forced_shutdown(sbi)))
>               return -EIO;
>  
> -     /*
> -      * We don't support synchronous mappings for non-DAX files. At least
> -      * until someone comes with a sensible use case.
> +     /* 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(file)) && (vma->vm_flags & VM_SYNC))
> +     if (!daxdev_mapping_supported(vma, dax_dev))
>               return -EOPNOTSUPP;
>  
>       file_accessed(file);
> -- 
> 2.20.1
> 
-- 
Jan Kara <address@hidden>
SUSE Labs, CR