Re: [PATCH v6 4/6] dax: check synchronous mapping is supported

Jan Kara
2019-04-23T14:27:29Z

On Tue 23-04-19 13:36:10, Pankaj Gupta wrote:
> This patch introduces 'daxdev_mapping_supported' helper
> which checks if 'MAP_SYNC' is supported with filesystem
> mapping. It also checks if corresponding dax_device is
> synchronous. Virtio pmem device is asynchronous and
> does not not support VM_SYNC.
>
> Suggested-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Pankaj Gupta <pagupta@redhat.com>

The patch looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> include/linux/dax.h | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index c97fc0cc7167..41b4a5db6305 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -41,6 +41,18 @@ void kill_dax(struct dax_device *dax_dev);
> void dax_write_cache(struct dax_device *dax_dev, bool wc);
> bool dax_write_cache_enabled(struct dax_device *dax_dev);
> bool dax_synchronous(struct dax_device *dax_dev);
> +/*
> + * Check if given mapping is supported by the file / underlying device.
> + */
> +static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
> + struct dax_device *dax_dev)
> +{
> + if (!(vma->vm_flags & VM_SYNC))
> + return true;
> + if (!IS_DAX(file_inode(vma->vm_file)))
> + return false;
> + return dax_synchronous(dax_dev);
> +}
> #else
> static inline struct dax_device *dax_get_by_host(const char *host)
> {
> @@ -68,6 +80,11 @@ static inline bool dax_write_cache_enabled(struct dax_device *dax_dev)
> {
> return false;
> }
> +static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
> + struct dax_device *dax_dev)
> +{
> + return !(vma->flags & VM_SYNC);
> +}
> #endif
>
> struct writeback_control;
> --
> 2.20.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR