On Mon 29-04-19 12:26:43, Goldwyn Rodrigues wrote:
> From: Adam Borowski <kilob...@angband.pl>
> 
> Used by userspace to detect DAX.
> [rgold...@suse.com: Added CONFIG_FS_DAX around mmap_supported_flags]

Why the CONFIG_FS_DAX bit? Your mmap(2) implementation understands
implications of MAP_SYNC flag and that's all that's needed to set
.mmap_supported_flags.

                                                                Honza

> Signed-off-by: Adam Borowski <kilob...@angband.pl>
> Signed-off-by: Goldwyn Rodrigues <rgold...@suse.com>
> ---
>  fs/btrfs/file.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index 9d5a3c99a6b9..362a9cf9dcb2 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -16,6 +16,7 @@
>  #include <linux/btrfs.h>
>  #include <linux/uio.h>
>  #include <linux/iversion.h>
> +#include <linux/mman.h>
>  #include "ctree.h"
>  #include "disk-io.h"
>  #include "transaction.h"
> @@ -3319,6 +3320,9 @@ const struct file_operations btrfs_file_operations = {
>       .splice_read    = generic_file_splice_read,
>       .write_iter     = btrfs_file_write_iter,
>       .mmap           = btrfs_file_mmap,
> +#ifdef CONFIG_FS_DAX
> +     .mmap_supported_flags = MAP_SYNC,
> +#endif
>       .open           = btrfs_file_open,
>       .release        = btrfs_release_file,
>       .fsync          = btrfs_sync_file,
> -- 
> 2.16.4
> 
-- 
Jan Kara <j...@suse.com>
SUSE Labs, CR
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