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[109.152.100.189]) by smtp.gmail.com with ESMTPSA id e6sm959732wme.27.2020.11.16.15.12.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Nov 2020 15:12:32 -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> <1605222042-44558-5-git-send-email-bijan.mottahedeh@oracle.com> <1e23c177-2be8-4046-c1ea-7ab263132bb5@gmail.com> <5ab203e3-8394-2dae-b48c-b30a1e16cc5d@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 4/8] io_uring: implement fixed buffers registration similar to fixed files Message-ID: Date: Mon, 16 Nov 2020 23:09:25 +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: <5ab203e3-8394-2dae-b48c-b30a1e16cc5d@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 16/11/2020 21:24, Bijan Mottahedeh wrote: > On 11/15/2020 5:33 AM, Pavel Begunkov wrote: >> On 12/11/2020 23:00, Bijan Mottahedeh wrote: >>> Apply fixed_rsrc functionality for fixed buffers support. >> >> I don't get it, requests with fixed files take a ref to a node (see >> fixed_file_refs) and put it on free, but I don't see anything similar >> here. Did you work around it somehow? > > No that's my oversight.  I think I wrongfully assumed that io_import_*fixed() would take care of that. > > Should I basically do something similar to io_file_get()/io_put_file()? If done in a dumb way, that'd mean extra pair of percpu get/put and +8B in io_kiocb. Frankly, I don't like that idea. However, if you don't split paths and make fixed_file_ref_node to supports all types of resources at the same time, it should be bearable. I.e. register removals of both types to a single node, and use ->fixed_file_refs for all request's resources. So you don't grow io_kiocb and do maximum one percpu_ref_get/put() pair per request. I'll send a small patch preparing grounds, because there is actually another nasty thing from past that needs to be reworked. > > io_import_fixed() > io_import_iovec_fixed() > -> io_buf_get() > > io_dismantle_io() > -> io_put_buf() > >> >> That's not critical for this particular patch as you still do full >> quisce in __io_uring_register(), but IIRC was essential for >> update/remove requests. > > That's something I'm not clear about.  Currently we quiesce for the following cases: > >         case IORING_UNREGISTER_FILES: >         case IORING_REGISTER_FILES_UPDATE: >         case IORING_REGISTER_BUFFERS_UPDATE: static bool io_register_op_must_quiesce(int op) { switch (op) { case IORING_UNREGISTER_FILES: case IORING_REGISTER_FILES_UPDATE: case IORING_REGISTER_PROBE: case IORING_REGISTER_PERSONALITY: case IORING_UNREGISTER_PERSONALITY: return false; default: return true; } } It returns _false_ for these cases, so _doesn't_ quiesce for them. > > I had assume I have to add IORING_UNREGISTER_BUFFERS as well.  But above, do we in fact the quiesce give the ref counts? > > Are you ok with the rest of the patches or should I address anything else? io_import_fixed() currently can be called twice, and that would give you 2 different bvecs. Hence after removing full quisce io_read() retrying short reads will probably be able to partially read into 2 different buffers. That really have to be fixed. I haven't looked the patchset properly yet. I'll reply to the cover-letter + a small comment below >>>   static ssize_t io_import_fixed(struct io_kiocb *req, int rw, >>>                      struct iov_iter *iter) >>>   { >>> @@ -2959,10 +2982,15 @@ static ssize_t io_import_fixed(struct io_kiocb *req, int rw, >>>       size_t offset; >>>       u64 buf_addr; >>>   +    /* attempt to use fixed buffers without having provided iovecs */ >>> +    if (unlikely(!ctx->buf_data)) >>> +        return -EFAULT; I removed it for files, because (ctx->buf_data) IFF (ctx->nr_user_bufs == 0), so the following ctx->nr_user_bufs check is enough. >>> + >>> +    buf_index = req->buf_index; >>>       if (unlikely(buf_index >= ctx->nr_user_bufs)) >>>           return -EFAULT; >>>       index = array_index_nospec(buf_index, ctx->nr_user_bufs); >>> -    imu = &ctx->user_bufs[index]; >>> +    imu = io_buf_from_index(ctx, index); >>>       buf_addr = req->rw.addr; >>>         /* overflow */ >>> @@ -8167,28 +8195,73 @@ static unsigned long ring_pages(unsigned sq_entries, unsigned cq_entries) >>>       return pages; >>>   } -- Pavel Begunkov