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[109.152.100.135]) by smtp.gmail.com with ESMTPSA id i16sm27599615wru.92.2020.11.17.03.07.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 17 Nov 2020 03:07:25 -0800 (PST) To: Bijan Mottahedeh , axboe@kernel.dk Cc: io-uring@vger.kernel.org References: <1605222042-44558-1-git-send-email-bijan.mottahedeh@oracle.com> <1605222042-44558-8-git-send-email-bijan.mottahedeh@oracle.com> From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Subject: Re: [PATCH 7/8] io_uring: support readv/writev with fixed buffers Message-ID: Date: Tue, 17 Nov 2020 11:04:17 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <1605222042-44558-8-git-send-email-bijan.mottahedeh@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 12/11/2020 23:00, Bijan Mottahedeh wrote: > Support readv/writev with fixed buffers, and introduce IOSQE_FIXED_BUFFER, > consistent with fixed files. I don't like it at all, see issues below. The actual implementation would be much uglier. I propose you to split the series and push separately. Your first 6 patches first, I don't have conceptual objections to them. Then registration sharing (I still need to look it up). And then we can return to this, if you're not yet convinced. > > Signed-off-by: Bijan Mottahedeh > --- > fs/io_uring.c | 59 ++++++++++++++++++++++++++++++++++++++++--- > include/uapi/linux/io_uring.h | 3 +++ > 2 files changed, 58 insertions(+), 4 deletions(-) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 6020fd2..12c4144 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -625,6 +625,7 @@ enum { > REQ_F_HARDLINK_BIT = IOSQE_IO_HARDLINK_BIT, > REQ_F_FORCE_ASYNC_BIT = IOSQE_ASYNC_BIT, > REQ_F_BUFFER_SELECT_BIT = IOSQE_BUFFER_SELECT_BIT, > + REQ_F_FIXED_BUFFER_BIT = IOSQE_FIXED_BUFFER_BIT, > > REQ_F_FAIL_LINK_BIT, > REQ_F_INFLIGHT_BIT, > @@ -681,8 +682,12 @@ enum { > REQ_F_WORK_INITIALIZED = BIT(REQ_F_WORK_INITIALIZED_BIT), > /* linked timeout is active, i.e. prepared by link's head */ > REQ_F_LTIMEOUT_ACTIVE = BIT(REQ_F_LTIMEOUT_ACTIVE_BIT), > + /* ctx owns buffer */ > + REQ_F_FIXED_BUFFER = BIT(REQ_F_FIXED_BUFFER_BIT), > }; > > +#define REQ_F_FIXED_RSRC (REQ_F_FIXED_FILE | REQ_F_FIXED_BUFFER) > + > struct async_poll { > struct io_poll_iocb poll; > struct io_poll_iocb *double_poll; > @@ -3191,6 +3196,46 @@ static ssize_t io_iov_buffer_select(struct io_kiocb *req, struct iovec *iov, > return __io_iov_buffer_select(req, iov, needs_lock); > } > > +static ssize_t io_import_iovec_fixed(int rw, struct io_kiocb *req, void *buf, > + unsigned segs, unsigned fast_segs, > + struct iovec **iovec, > + struct iov_iter *iter) > +{ > + struct io_ring_ctx *ctx = req->ctx; > + struct io_mapped_ubuf *imu; > + struct iovec *iov; > + u16 index, buf_index; > + ssize_t ret; > + unsigned long seg; > + > + if (unlikely(!ctx->buf_data)) > + return -EFAULT; > + > + ret = import_iovec(rw, buf, segs, fast_segs, iovec, iter); Did you test it? import_iovec() does access_ok() against each iov_base, which in your case are an index. > + if (ret < 0) > + return ret; > + > + iov = (struct iovec *)iter->iov; > + > + for (seg = 0; seg < iter->nr_segs; seg++) { > + buf_index = *(u16 *)(&iov[seg].iov_base); That's ugly, and also not consistent with rw_fixed, because iov_base is used to calculate offset. > + if (unlikely(buf_index < 0 || buf_index >= ctx->nr_user_bufs)) > + return -EFAULT; > + > + index = array_index_nospec(buf_index, ctx->nr_user_bufs); > + imu = io_buf_from_index(ctx, index); > + if (!imu->ubuf || !imu->len) > + return -EFAULT; > + if (iov[seg].iov_len > imu->len) > + return -EFAULT; > + > + iov[seg].iov_base = (void *)imu->ubuf; Nope, that's not different from non registered version. What import_fixed actually do is setting up the iter argument to point to a bvec (a vector of struct page *). So it either would need to keep a vector of bvecs, that's a vector of vectors, that's not supported by iter, etc., so you'll also need to iterate over them in io_read/write and so on. Or flat 2D structure into 1D, but that's still ugly. > + ret += iov[seg].iov_len; > + } > + > + return ret; > +} > + > static ssize_t io_import_iovec(int rw, struct io_kiocb *req, > struct iovec **iovec, struct iov_iter *iter, > bool needs_lock) > @@ -3201,6 +3246,12 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req, > u8 opcode; > > opcode = req->opcode; > + > + if ((opcode == IORING_OP_READV || opcode == IORING_OP_WRITEV) && > + req->flags & REQ_F_FIXED_BUFFER) > + return (io_import_iovec_fixed(rw, req, buf, sqe_len, > + UIO_FASTIOV, iovec, iter)); > + > if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) { > *iovec = NULL; > return io_import_fixed(req, rw, iter); > @@ -5692,7 +5743,7 @@ static int io_timeout_remove_prep(struct io_kiocb *req, > { > if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL)) > return -EINVAL; > - if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT))) > + if (unlikely(req->flags & (REQ_F_FIXED_RSRC | REQ_F_BUFFER_SELECT))) Why it's here? #define REQ_F_FIXED_RSRC (REQ_F_FIXED_FILE | REQ_F_FIXED_BUFFER) So, why do you | with REQ_F_BUFFER_SELECT again here? > return -EINVAL; > if (sqe->ioprio || sqe->buf_index || sqe->len || sqe->timeout_flags) > return -EINVAL; > @@ -5867,7 +5918,7 @@ static int io_async_cancel_prep(struct io_kiocb *req, > { > if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL)) > return -EINVAL; > - if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT))) > + if (unlikely(req->flags & (REQ_F_FIXED_RSRC | REQ_F_BUFFER_SELECT))) > return -EINVAL; > if (sqe->ioprio || sqe->off || sqe->len || sqe->cancel_flags) > return -EINVAL; > @@ -5889,7 +5940,7 @@ static int io_rsrc_update_prep(struct io_kiocb *req, > { > if (unlikely(req->ctx->flags & IORING_SETUP_SQPOLL)) > return -EINVAL; > - if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT))) > + if (unlikely(req->flags & (REQ_F_FIXED_RSRC | REQ_F_BUFFER_SELECT))) > return -EINVAL; > if (sqe->ioprio || sqe->rw_flags) > return -EINVAL; > @@ -6740,7 +6791,7 @@ static inline bool io_check_restriction(struct io_ring_ctx *ctx, > > #define SQE_VALID_FLAGS (IOSQE_FIXED_FILE|IOSQE_IO_DRAIN|IOSQE_IO_LINK| \ > IOSQE_IO_HARDLINK | IOSQE_ASYNC | \ > - IOSQE_BUFFER_SELECT) > + IOSQE_BUFFER_SELECT | IOSQE_FIXED_BUFFER) > > static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req, > const struct io_uring_sqe *sqe, > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h > index 17682b5..41da59c 100644 > --- a/include/uapi/linux/io_uring.h > +++ b/include/uapi/linux/io_uring.h > @@ -70,6 +70,7 @@ enum { > IOSQE_IO_HARDLINK_BIT, > IOSQE_ASYNC_BIT, > IOSQE_BUFFER_SELECT_BIT, > + IOSQE_FIXED_BUFFER_BIT, > }; > > /* > @@ -87,6 +88,8 @@ enum { > #define IOSQE_ASYNC (1U << IOSQE_ASYNC_BIT) > /* select buffer from sqe->buf_group */ > #define IOSQE_BUFFER_SELECT (1U << IOSQE_BUFFER_SELECT_BIT) > +/* use fixed buffer set */ > +#define IOSQE_FIXED_BUFFER (1U << IOSQE_FIXED_BUFFER_BIT) Unfortenatuly, we're almost out of flags bits -- it's a 1 byte field and 6 bits are already taken. Let's not use it. -- Pavel Begunkov