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Tue, 26 May 2020 07:35:06 -0700 (PDT) To: Xiaoguang Wang , io-uring@vger.kernel.org Cc: axboe@kernel.dk, joseph.qi@linux.alibaba.com References: <20200526064330.9322-1-xiaoguang.wang@linux.alibaba.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 1/3] io_uring: don't use req->work.creds for inline requests Message-ID: Date: Tue, 26 May 2020 17:33:51 +0300 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: <20200526064330.9322-1-xiaoguang.wang@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 26/05/2020 09:43, Xiaoguang Wang wrote: > In io_init_req(), if uers requires a new credentials, currently we'll > save it in req->work.creds, but indeed io_wq_work is designed to describe > needed running environment for requests that will go to io-wq, if one > request is going to be submitted inline, we'd better not touch io_wq_work. > Here add a new 'const struct cred *creds' in io_kiocb, if uers requires a > new credentials, inline requests can use it. > > This patch is also a preparation for later patch. What's the difference from keeping only one creds field in io_kiocb (i.e. req->work.creds), but handling it specially (i.e. always initialising)? It will be a lot easier than tossing it around. Also, the patch doubles {get,put}_creds() for sqe->personality case, and that's extra atomics without a good reason. > > Signed-off-by: Xiaoguang Wang > --- > fs/io_uring.c | 23 +++++++++++++++-------- > 1 file changed, 15 insertions(+), 8 deletions(-) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 2af87f73848e..788d960abc69 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -635,6 +635,7 @@ struct io_kiocb { > unsigned int flags; > refcount_t refs; > struct task_struct *task; > + const struct cred *creds; > unsigned long fsize; > u64 user_data; > u32 result; > @@ -1035,8 +1036,10 @@ static inline void io_req_work_grab_env(struct io_kiocb *req, > mmgrab(current->mm); > req->work.mm = current->mm; > } > - if (!req->work.creds) > + if (!req->creds) > req->work.creds = get_current_cred(); > + else > + req->work.creds = get_cred(req->creds); > if (!req->work.fs && def->needs_fs) { > spin_lock(¤t->fs->lock); > if (!current->fs->in_exec) { > @@ -1368,6 +1371,9 @@ static void __io_req_aux_free(struct io_kiocb *req) > if (req->flags & REQ_F_NEED_CLEANUP) > io_cleanup_req(req); > > + if (req->creds) > + put_cred(req->creds); > + > kfree(req->io); > if (req->file) > io_put_file(req, req->file, (req->flags & REQ_F_FIXED_FILE)); > @@ -5673,13 +5679,13 @@ static void __io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe) > again: > linked_timeout = io_prep_linked_timeout(req); > > - if (req->work.creds && req->work.creds != current_cred()) { > + if (req->creds && req->creds != current_cred()) { > if (old_creds) > revert_creds(old_creds); > - if (old_creds == req->work.creds) > + if (old_creds == req->creds) > old_creds = NULL; /* restored original creds */ > else > - old_creds = override_creds(req->work.creds); > + old_creds = override_creds(req->creds); > } > > ret = io_issue_sqe(req, sqe, true); > @@ -5970,11 +5976,12 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req, > > id = READ_ONCE(sqe->personality); > if (id) { > - req->work.creds = idr_find(&ctx->personality_idr, id); > - if (unlikely(!req->work.creds)) > + req->creds = idr_find(&ctx->personality_idr, id); > + if (unlikely(!req->creds)) > return -EINVAL; > - get_cred(req->work.creds); > - } > + get_cred(req->creds); > + } else > + req->creds = NULL; > > /* same numerical values with corresponding REQ_F_*, safe to copy */ > req->flags |= sqe_flags; > -- Pavel Begunkov