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Thu, 30 Jan 2025 09:22:26 +0000 (GMT) Received: from epsmgms1p2new.samsung.com (unknown [182.195.42.42]) by epsmtrp1.samsung.com (KnoxPortal) with ESMTP id 20250130092226epsmtrp1fc9bfa099aecd7f940cedb88d2feb898~fbgRbMQ-q2846128461epsmtrp1r; Thu, 30 Jan 2025 09:22:26 +0000 (GMT) X-AuditID: b6c32a50-7ebff7000000721c-6c-679b44d2dd6f Received: from epsmtip1.samsung.com ( [182.195.34.30]) by epsmgms1p2new.samsung.com (Symantec Messaging Gateway) with SMTP id 9E.DC.18949.2D44B976; Thu, 30 Jan 2025 18:22:26 +0900 (KST) Received: from [107.122.11.51] (unknown [107.122.11.51]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20250130092224epsmtip1d983c41a07ed41df2dd58005c2805c44~fbgP7FMmy1288612886epsmtip15; Thu, 30 Jan 2025 09:22:24 +0000 (GMT) Message-ID: Date: Thu, 30 Jan 2025 14:52:23 +0530 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC 0/3] Btrfs checksum offload To: Christoph Hellwig Cc: josef@toxicpanda.com, dsterba@suse.com, clm@fb.com, axboe@kernel.dk, kbusch@kernel.org, linux-btrfs@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, gost.dev@samsung.com Content-Language: en-US From: Kanchan Joshi In-Reply-To: <20250129153524.GB5356@lst.de> Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrJJsWRmVeSWpSXmKPExsWy7bCmhu4ll9npBg1fVSxW3+1ns5jUP4Pd 4sKPRiaLmwd2MlmsXH2UyeLPQ0OLSYeuMVrsvaVtcenxCnaL+cuesjtweUxsfsfucflsqcem VZ1sHpuX1HvsvtnA5tG3ZRWjx/otV1k8JmzeyOrxeZNcAGdUtk1GamJKapFCal5yfkpmXrqt kndwvHO8qZmBoa6hpYW5kkJeYm6qrZKLT4CuW2YO0JVKCmWJOaVAoYDE4mIlfTubovzSklSF jPziElul1IKUnAKTAr3ixNzi0rx0vbzUEitDAwMjU6DChOyMTf1bWQtuclb8nWLUwPiUvYuR k0NCwESi7ch7li5GLg4hgT2MEpNnrGGDcD4xSqyY28wI4XxjlDhz6QQrTMv+O4+YIRJ7GSW2 v+iAct4ySmzqXswCUsUrYCfxePIiZhCbRUBV4u+vq0wQcUGJkzOfgNWICshL3L81A+gQdg5h AV2JHdEgUREBJYmnr86CLWYWuMAosXLPI7BWZgFxiVtP5gPZHBxsApoSFyaXgoQ5BbQlfs88 wwZRIi+x/e0csHMkBPZwSOw/+50R4mgXid+bT0LZwhKvjm+B+l9K4mV/G5SdLfHg0QMWCLtG YsfmPqiH7SUa/txgBdnLDLR3/S59iF18Er2/n4CdIyHAK9HRJgRRrShxb9JTqE5xiYczlkDZ HhIvJhyDBu5qRom7N6+xTWBUmIUUKLOQfDkLyTuzEDYvYGRZxSiVWlCcm56abFpgqJuXWg6P 7+T83E2M4DSsFbCDcfWGv3qHGJk4GA8xSnAwK4nwxp6bkS7Em5JYWZValB9fVJqTWnyI0RQY PROZpUST84GZIK8k3tDE0sDEzMzMxNLYzFBJnLd5Z0u6kEB6YklqdmpqQWoRTB8TB6dUAxNT 6B7/Q7cnMGRxvNsr1BZwaUKhOAPP0vdnJ9Sb+M7LLAyX/GVuPP33t3PbS8yLLzervbpj+O7o hi0dn6ynL/8q5HYtcpfQ/z2fL+9Yd2dtwBxxa9buGcnSaZ58fw6LG7LNFl6ZUtGRcGqJARdj SrbPpbn7pnf/i+3KLn7y/oKCkdOv+62PBPTFfN85Orto3CzNsDvnu3qJ1OwpdlXrMpdOWLru 90zd4FMZWyTjp/R9kkk+uzXi5uuf4p6LNHaLBE+86eK4oj8ogDUo5y5vK6/YYkZJ/kqhzK/B k1cFNouxrvzMd0C7oH+6gdVL65ZgAZfey09rV0srbmPumJewuvZ/hPGSJrvnmjHZc/5r3ldi Kc5INNRiLipOBAAhsS8CTAQAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprCIsWRmVeSWpSXmKPExsWy7bCSnO4ll9npBv+usFqsvtvPZjGpfwa7 xYUfjUwWNw/sZLJYufook8Wfh4YWkw5dY7TYe0vb4tLjFewW85c9ZXfg8pjY/I7d4/LZUo9N qzrZPDYvqffYfbOBzaNvyypGj/VbrrJ4TNi8kdXj8ya5AM4oLpuU1JzMstQifbsEroxN/VtZ C25yVvydYtTA+JS9i5GTQ0LARGL/nUfMXYxcHEICuxkldvbNYoRIiEs0X/sBVSQssfLfc3aI oteMEq2d05lAErwCdhKPJy9iBrFZBFQl/v66ChUXlDg58wkLiC0qIC9x/9YMoGZ2DmEBXYkd 0SBREQEliaevzjKCjGQWuMAoseTyEUaI+asZJXb9PwJ2BDPQEbeezAeaycHBJqApcWFyKUiY U0Bb4vfMM2wQJWYSXVu7oMrlJba/ncM8gVFoFpIrZiGZNAtJyywkLQsYWVYxSqYWFOem5xYb FhjlpZbrFSfmFpfmpesl5+duYgRHnJbWDsY9qz7oHWJk4mA8xCjBwawkwht7bka6EG9KYmVV alF+fFFpTmrxIUZpDhYlcd5vr3tThATSE0tSs1NTC1KLYLJMHJxSDUx8+xiyZj76+Gm2YdND WXX1KSHGbx+1MrWy7jyp+D+v0XDm77vP1OKjmNZ6Nrx54Ppraw1P/2bBNbYcHyx9mm++ufrV u5exRnKXcCFr6++VT4uUPmnkqwfw7bJj0LB3NhOUXfdk4fIrShPLLR7pyh2UTrQ6wnq/0ufa wVnJgWrxIqayOWc+Xli8pXl/m5TV25avT+e4bF+R1VWl5hJvUX7N+mxIYK3umrrp9r1S7nV+ gXEnmeb/3P5z4hObnnUNr64Vsh9a7fRP5fY7tV0rz89SbN4XmBV2N6BhQdOdg1zf3kjetZrw x3SbMluV8qHvTUVaYT7r2jK2rVgZK3/ZO0rbfHKkVjtf9e7N84qvrVFiKc5INNRiLipOBACO 1ZfqJwMAAA== X-CMS-MailID: 20250130092226epcas5p4c8830a18efedb85436a2167c5146058c X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20250129141039epcas5p11feb1be4124c0db3c5223325924183a3 References: <20250129140207.22718-1-joshi.k@samsung.com> <20250129153524.GB5356@lst.de> On 1/29/2025 9:05 PM, Christoph Hellwig wrote: >> This patch series: (a) adds checksum offload awareness to the >> block layer (patch #1), > I've skipped over the patches and don't understand what this offload > awareness concept does compared the file system simply attaching PI > metadata. Difference is that FS does not have to attach any PI for offload. Offload is about the Host doing as little as possible, and the closest we get there is by setting PRACT bit. Attaching PI is not really needed, neither for FS nor for block-layer, for pure offload. When device has "ms == pi_size" format, we only need to send I/O with PRACT set and device take care of attaching integrity buffer and checksum generation/verification. This is abstracted as 'offload type 1' in this series. For other format "ms > pi_size" also we set the PRACT but integrity buffer also needs to be passed. This is abstracted as 'offload type 2'. Still offload as the checksum processing is done only by the device. Block layer Auto-PI is a good place because all above details are common and remain abstracted, while filesystems only need to decide whether they want to send the flag (REQ_INTEGRITY_OFFLOAD) to use the facility.