Re: [PATCH] DAX: enable iostat for read/write
From: Dan Williams
Date: Fri Oct 14 2016 - 13:35:35 EST
On Fri, Oct 14, 2016 at 10:25 AM, Toshi Kani <toshi.kani@xxxxxxx> wrote:
> DAX IO path does not support iostat, but its metadata IO path does.
> Therefore, iostat shows metadata IO statistics only, which has been
> confusing to users.
> Add iostat support to the DAX read/write path.
> Note, iostat still does not support the DAX mmap path as it allows
> user applications to access directly.
> Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> fs/dax.c | 37 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 37 insertions(+)
> diff --git a/fs/dax.c b/fs/dax.c
> index 014defd..3aaaac2 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -144,6 +144,34 @@ static sector_t to_sector(const struct buffer_head *bh,
> return sector;
> +static void dax_iostat_start(struct gendisk *disk, struct iov_iter *iter,
> + unsigned long *start)
> + int rw = iov_iter_rw(iter);
> + int sec = iov_iter_count(iter) >> 9;
Should this be a minimum of one sector since we allow unaligned
transfers through this interface?
...or is iov_iter_count() somehow guaranteed to be sector aligned here?