On 25/02/2020 01:34, Jens Axboe wrote:
> On 2/24/20 8:35 AM, Jens Axboe wrote:
>> On 2/24/20 1:32 AM, Pavel Begunkov wrote:
>>> *on top of for-5.6 + async patches*
>>>
>>> Not the fastets implementation, but I'd need to stir up/duplicate
>>> splice.c bits to do it more efficiently.
>>>
>>> note: rebase on top of the recent inflight patchset.
>>
>> Let's get this queued up, looks good to go to me. Do you have a few
>> liburing test cases we can add for this?
>
> Seems to me like we have an address space issue for the off_in and
Is that a problem? From the old fixing thread loop_rw_iter() it appeared
to me, that it's ok to pass a kernel address as a user one.
f_op->write of some implemented through the same copy_to_user().
> off_out parameters. Why aren't we passing in pointers to these
> and making them work like regular splice?
That's one extra copy_to_user() + copy_from_user(), which I hope to remove
in the future. And I'm not really a fan of such API, and would prefer to give
away such tracking to the userspace.
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 792ef01a521c..b0cfd68be8c9 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -448,8 +448,8 @@ struct io_epoll {
> struct io_splice {
> struct file *file_out;
> struct file *file_in;
> - loff_t off_out;
> - loff_t off_in;
> + loff_t __user *off_out;
> + loff_t __user *off_in;
> u64 len;
> unsigned int flags;
> };
> @@ -2578,8 +2578,8 @@ static int io_splice_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> return 0;
>
> sp->file_in = NULL;
> - sp->off_in = READ_ONCE(sqe->splice_off_in);
> - sp->off_out = READ_ONCE(sqe->off);
> + sp->off_in = u64_to_user_ptr(READ_ONCE(sqe->splice_off_in));
> + sp->off_out = u64_to_user_ptr(READ_ONCE(sqe->off));
> sp->len = READ_ONCE(sqe->len);
> sp->flags = READ_ONCE(sqe->splice_flags);
>
> @@ -2614,7 +2614,6 @@ static int io_splice(struct io_kiocb *req, struct io_kiocb **nxt,
> struct file *in = sp->file_in;
> struct file *out = sp->file_out;
> unsigned int flags = sp->flags & ~SPLICE_F_FD_IN_FIXED;
> - loff_t *poff_in, *poff_out;
> long ret;
>
> if (force_nonblock) {
> @@ -2623,9 +2622,7 @@ static int io_splice(struct io_kiocb *req, struct io_kiocb **nxt,
> flags |= SPLICE_F_NONBLOCK;
> }
>
> - poff_in = (sp->off_in == -1) ? NULL : &sp->off_in;
> - poff_out = (sp->off_out == -1) ? NULL : &sp->off_out;
> - ret = do_splice(in, poff_in, out, poff_out, sp->len, flags);
> + ret = do_splice(in, sp->off_in, out, sp->off_out, sp->len, flags);
> if (force_nonblock && ret == -EAGAIN)
> return -EAGAIN;
>
>
--
Pavel Begunkov
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