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SubjectRe: [RESEND PATCH 4/4] aio: use iovec array rather than the single one
On Wed, Jul 23, 2014 at 06:03:54PM +0800, Gu Zheng wrote:
> Previously, we only offer a single iovec to handle all the read/write cases, so
> the PREADV/PWRITEV request always need to alloc more iovec buffer when copying
> user vectors.
> If we use a tmp iovec array rather than the single one, some small PREADV/PWRITEV
> workloads(vector size small than the tmp buffer) will not need to alloc more
> iovec buffer when copying user vectors.

Thanks Gu -- applied to my aio-next tree at
git://git.kvack.org/~bcrl/aio-next.git .

-ben

> Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
> ---
> fs/aio.c | 10 +++++-----
> 1 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index f1fede2..df3491a 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1267,12 +1267,12 @@ static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
> if (compat)
> ret = compat_rw_copy_check_uvector(rw,
> (struct compat_iovec __user *)buf,
> - *nr_segs, 1, *iovec, iovec);
> + *nr_segs, UIO_FASTIOV, *iovec, iovec);
> else
> #endif
> ret = rw_copy_check_uvector(rw,
> (struct iovec __user *)buf,
> - *nr_segs, 1, *iovec, iovec);
> + *nr_segs, UIO_FASTIOV, *iovec, iovec);
> if (ret < 0)
> return ret;
>
> @@ -1309,7 +1309,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
> fmode_t mode;
> aio_rw_op *rw_op;
> rw_iter_op *iter_op;
> - struct iovec inline_vec, *iovec = &inline_vec;
> + struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
> struct iov_iter iter;
>
> switch (opcode) {
> @@ -1344,7 +1344,7 @@ rw_common:
> if (!ret)
> ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
> if (ret < 0) {
> - if (iovec != &inline_vec)
> + if (iovec != inline_vecs)
> kfree(iovec);
> return ret;
> }
> @@ -1391,7 +1391,7 @@ rw_common:
> return -EINVAL;
> }
>
> - if (iovec != &inline_vec)
> + if (iovec != inline_vecs)
> kfree(iovec);
>
> if (ret != -EIOCBQUEUED) {
> --
> 1.7.7

--
"Thought is the essence of where you are now."


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