Re: [PATCH 06/10] nvdimm-btt: use bvec_kmap_local in btt_rw_integrity

Ira Weiny
2022-03-01T03:59:10Z

On Tue, Feb 22, 2022 at 04:51:52PM +0100, Christoph Hellwig wrote:
> Using local kmaps slightly reduces the chances to stray writes, and
> the bvec interface cleans up the code a little bit.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/nvdimm/btt.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> index cbd994f7f1fe6..9613e54c7a675 100644
> --- a/drivers/nvdimm/btt.c
> +++ b/drivers/nvdimm/btt.c
> @@ -1163,17 +1163,15 @@ static int btt_rw_integrity(struct btt *btt, struct bio_integrity_payload *bip,
> */
>
> cur_len = min(len, bv.bv_len);
> - mem = kmap_atomic(bv.bv_page);
> + mem = bvec_kmap_local(&bv);
> if (rw)
> - ret = arena_write_bytes(arena, meta_nsoff,
> - mem + bv.bv_offset, cur_len,
> + ret = arena_write_bytes(arena, meta_nsoff, mem, cur_len,

Why drop bv.bv_offset here and below?

Ira

> NVDIMM_IO_ATOMIC);
> else
> - ret = arena_read_bytes(arena, meta_nsoff,
> - mem + bv.bv_offset, cur_len,
> + ret = arena_read_bytes(arena, meta_nsoff, mem, cur_len,
> NVDIMM_IO_ATOMIC);
>
> - kunmap_atomic(mem);
> + kunmap_local(mem);
> if (ret)
> return ret;
>
> --
> 2.30.2
>
>