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Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH 2/4] nvme: use bio_integrity_map_user Content-Language: en-US To: Keith Busch , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, io-uring@vger.kernel.org Cc: axboe@kernel.dk, hch@lst.de, martin.petersen@oracle.com, Keith Busch From: Kanchan Joshi In-Reply-To: <20231018151843.3542335-3-kbusch@meta.com> Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrCJsWRmVeSWpSXmKPExsWy7bCmhu5ScctUg0tHTSxW3+1ns1i5+iiT xbvWcywWkw5dY7Q4c3Uhi8XeW9oW85c9ZbdYfvwfkwOHx+WzpR6bVnWyeWxeUu+x+2YDm8e5 ixUeH5/eYvH4vEkugD0q2yYjNTEltUghNS85PyUzL91WyTs43jne1MzAUNfQ0sJcSSEvMTfV VsnFJ0DXLTMH6CIlhbLEnFKgUEBicbGSvp1NUX5pSapCRn5xia1SakFKToFJgV5xYm5xaV66 Xl5qiZWhgYGRKVBhQnbGjEOL2AqesFWcuNDF3sB4kLWLkZNDQsBEoufgOiCbi0NIYDejxMF3 O5hAEkICnxglZi1wgUgA2Uf617LDdBz+dIUJIrGTUeLakmdQzltGiTkfDzKDVPEK2Ek0bW1h AbFZBFQl9i67zAoRF5Q4OfMJWFxUIEni19U5jF2MHBzCApYSU6/HgISZBcQlbj2ZD3aFiECV RN+0n2wQ8TiJpUdmMIOUswloSlyYXAoS5hQwl5hzfgoLRIm8xPa3c5hBzpEQmMghcffnJqg3 XST+PIV5WVji1fEtUM9ISXx+t5cNwk6WuDTzHBOEXSLxeM9BKNteovVUP9heZqC963fpQ+zi k+j9/YQJJCwhwCvR0SYEUa0ocW/SU6hN4hIPZyyBsj0kXl9/Ag3o7YwS+w/MYZ7AqDALKVBm Ifl+FpJ3ZiFsXsDIsopRMrWgODc9tdi0wDAvtRwe3cn5uZsYwclVy3MH490HH/QOMTJxMB5i lOBgVhLhjfSxSBXiTUmsrEotyo8vKs1JLT7EaAqMnYnMUqLJ+cD0nlcSb2hiaWBiZmZmYmls Zqgkzvu6dW6KkEB6YklqdmpqQWoRTB8TB6dUA5Meg55Wj9JD7vMTDmt4XZLKf7OWdW2L6urt uzUuH7L8tctDovFWkGULT9JDmzX/p+a1xhxq2OnxQSP1ekvZgycGS7NuTSzal7jj/v8P0Ymd t+f4G17dUaezL3VtywM/xovt6ZE/Mh8VFT6Yu//Su3Uz+j5O/N9dypngeEdZ80lNo6qiaUva jDKLp7xK3SvOm9VPZeH/l/nm0sLLcrmX30pkLNRbwOpa9jebb/oz7oVbj9w/92zJA5t3mzau PWj1bnXohZP7dpyUkOVTarwiFKLg+tS6Vk7siY46x475108xvnrnoWR3g//ewoxdW629bvlt ORd1ZetElpQ9OzJ7r2m8Y19qvLrYLMYia/LMaPEPSizFGYmGWsxFxYkAU4S/XzcEAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrDLMWRmVeSWpSXmKPExsWy7bCSnO4ScctUg765Char7/azWaxcfZTJ 4l3rORaLSYeuMVqcubqQxWLvLW2L+cueslssP/6PyYHD4/LZUo9NqzrZPDYvqffYfbOBzePc xQqPj09vsXh83iQXwB7FZZOSmpNZllqkb5fAlTHj0CK2gidsFScudLE3MB5k7WLk5JAQMJE4 /OkKUxcjF4eQwHZGiWN3PrNBJMQlmq/9YIewhSVW/nsOZgsJvGaUOP2pFsTmFbCTaNrawgJi swioSuxddpkVIi4ocXLmE7C4qECSxJ77jUALODiEBSwlpl6PAQkzA42/9WQ+E4gtIlAlsf/H WSaIeJzE/0uNCPdMnXqFBaSXTUBT4sLkUpAaTgFziTnnp7BA1JtJdG3tYoSw5SW2v53DPIFR aBaSK2YhWTcLScssJC0LGFlWMYqmFhTnpucmFxjqFSfmFpfmpesl5+duYgRHkFbQDsZl6//q HWJk4mA8xCjBwawkwhvpY5EqxJuSWFmVWpQfX1Sak1p8iFGag0VJnFc5pzNFSCA9sSQ1OzW1 ILUIJsvEwSnVwLTi8PdJFx4/8bZgNnus3LTpkaVrx4PZiyZsV7kqsejsxMdMSu+SPge7TjzB c8dt+hKJWzN0n341ulu6b43tqpWywU78Tz6JPMzy+infWq35nHvxkwaZJaFPA1IvTG25rj6x ZdqOsgvlDdf0V6nKbD0RVVXe5r587Tkxpe1NT6fHevuci+urUZqQKvQ9eZPffakEjmWtUaxr yq0ehiiG71GbJHVu2Ueeo/4nFgQxObDFv/h8pVHd7264rhH/xAdRRfwrOVTzXa60Ol8IFVj1 yW/1S/3dlzbk+wvmZEtJ98/ua57TeefKH9uF9gv4Fj9Lv2wbUyU0WcniRMfOjCRjpfoHKdUC u0TnhurPUCk5xajEUpyRaKjFXFScCACoklrHDwMAAA== X-CMS-MailID: 20231025132700epcas5p4f8535021e9d20d9138f6b7760496dfde X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20231018153235epcas5p3c89cd65ddf817849f7450e8043538375 References: <20231018151843.3542335-1-kbusch@meta.com> <20231018151843.3542335-3-kbusch@meta.com> Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 10/18/2023 8:48 PM, Keith Busch wrote: > From: Keith Busch > > Map user metadata buffers directly instead of maintaining a complicated > copy buffer. > > Now that the bio tracks the metadata through its bip, nvme doesn't need > special metadata handling, callbacks, or additional fields in the pdu. > This greatly simplifies passthrough handling and avoids a "might_fault" > copy_to_user in the completion path. This also creates pdu space to > track the original request separately from its bio, further simplifying > polling without relying on special iouring fields. > > The downside is that nvme requires the metadata buffer be physically > contiguous, so user space will need to utilize huge pages if the buffer > needs to span multiple pages. I did not notice where this downside part is getting checked in the code.