On 25/02/2020 01:51, Pavel Begunkov wrote:
> 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().
Either I finally need to check myself how the protection is implemented...
>
>> 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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