Re: [PATCH] io_uring: let IORING_OP_FILES_UPDATE support to choose fixed file slots

[Jens Axboe <axboe@kernel.dk>]

On 5/30/22 6:46 AM, Xiaoguang Wang wrote:
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 6d91148e9679..58514b8048da 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -5945,16 +5948,20 @@ static int io_statx(struct io_kiocb *req, unsigned int issue_flags)
>  	return 0;
>  }
>  
> +#define IORING_CLOSE_FD_AND_FILE_SLOT 1
> +
>  static int io_close_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  {
> -	if (sqe->off || sqe->addr || sqe->len || sqe->rw_flags || sqe->buf_index)
> +	if (sqe->off || sqe->addr || sqe->len || sqe->buf_index)
>  		return -EINVAL;
>  	if (req->flags & REQ_F_FIXED_FILE)
>  		return -EBADF;
>  
>  	req->close.fd = READ_ONCE(sqe->fd);
>  	req->close.file_slot = READ_ONCE(sqe->file_index);
> -	if (req->close.file_slot && req->close.fd)
> +	req->close.flags = READ_ONCE(sqe->close_flags);

This needs a:

	if (req->closeflags & ~IORING_CLOSE_FD_AND_FILE_SLOT)
		return -EINVAL;

to be future proof in terms of new flags.

> +	if (!(req->close.flags & IORING_CLOSE_FD_AND_FILE_SLOT) &&
> +	    req->close.file_slot && req->close.fd)
>  		return -EINVAL;
>  
>  	return 0;
> @@ -5970,7 +5977,8 @@ static int io_close(struct io_kiocb *req, unsigned int issue_flags)
>  
>  	if (req->close.file_slot) {
>  		ret = io_close_fixed(req, issue_flags);
> -		goto err;
> +		if (ret || !(req->close.flags & IORING_CLOSE_FD_AND_FILE_SLOT))
> +			goto err;
>  	}
>  
>  	spin_lock(&files->file_lock);
> @@ -8003,23 +8011,63 @@ static int io_files_update_prep(struct io_kiocb *req,
>  	return 0;
>  }
>  
> +static int io_files_update_with_index_alloc(struct io_kiocb *req,
> +					    unsigned int issue_flags)
> +{
> +	__s32 __user *fds = u64_to_user_ptr(req->rsrc_update.arg);
> +	struct file *file;
> +	unsigned int done, nr_fds = req->rsrc_update.nr_args;
> +	int ret, fd;
> +
> +	for (done = 0; done < nr_fds; done++) {
> +		if (copy_from_user(&fd, &fds[done], sizeof(fd))) {
> +			ret = -EFAULT;
> +			break;
> +		}
> +
> +		file = fget(fd);
> +		if (!file) {
> +			ret = -EBADF;
> +			goto out;
> +		}
> +		ret = io_fixed_fd_install(req, issue_flags, file,
> +					  IORING_FILE_INDEX_ALLOC);
> +		if (ret < 0)
> +			goto out;
> +		if (copy_to_user(&fds[done], &ret, sizeof(ret))) {
> +			ret = -EFAULT;
> +			__io_close_fixed(req, issue_flags, ret);
> +			break;
> +		}
> +	}
> +
> +out:
> +	if (done)
> +		return done;
> +	return ret;
> +}
> +
>  static int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
>  {
>  	struct io_ring_ctx *ctx = req->ctx;
>  	struct io_uring_rsrc_update2 up;
>  	int ret;
>  
> -	up.offset = req->rsrc_update.offset;
> -	up.data = req->rsrc_update.arg;
> -	up.nr = 0;
> -	up.tags = 0;
> -	up.resv = 0;
> -	up.resv2 = 0;
> +	if (req->rsrc_update.offset == IORING_FILE_INDEX_ALLOC) {
> +		ret = io_files_update_with_index_alloc(req, issue_flags);
> +	} else {
> +		up.offset = req->rsrc_update.offset;
> +		up.data = req->rsrc_update.arg;
> +		up.nr = 0;
> +		up.tags = 0;
> +		up.resv = 0;
> +		up.resv2 = 0;

Move 'up' into this branch?

Do you have a liburing test case for this as well?

-- 
Jens Axboe