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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ExdKGtIS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ExdKGtIS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96B0F1F000E9; Wed, 22 Jul 2026 01:12:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784682773; bh=BIdjmMVLRz3VCvUV0PSwHPPOyO0nL/LWpeFc+B3fVhs=; h=Date:From:Subject:To:Cc:References:In-Reply-To; b=ExdKGtIS3KaAVmV2MovbHTR8bS2bslDyVvdaBbD6WaAZRcWRRxogqK4EyRI5n7+I9 l+VTw8ADeq068x+y/bqXGfJ/X2KNEU8BsHMST0PMYHoMpE9Dgss8knjma3HrWgkGBn 3M9tgMPMTFy4AuxitJy4nH4P1o/TQGzIng1ueq9CRYzhT9NwRFusx9JtwB4pDiEm+t h41XUjRa/igm1pTnXAGah/ZITb+T7pRAgcupFyvmzmNEq0w2AzfANA+mykcv+w/dQ+ JUBCSBypEQ34Ceo4aGUrHwSEtqCUyk5USOcaBbJhlprPhGNlGQlZ8VQ62NisqjmvKJ EyogBoNdkMyvg== Message-ID: <1a0bb2ad-c175-4cae-9e3f-79fbf69ce735@kernel.org> Date: Wed, 22 Jul 2026 09:12:48 +0800 Precedence: bulk X-Mailing-List: fstests@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Chao Yu Subject: Re: [f2fs-dev] [PATCH] generic/064: allow 50 extents on F2FS after fcollapse To: Christoph Hellwig Cc: chao@kernel.org, Zorro Lang , Jan Prusakowski , linux-f2fs-devel@lists.sourceforge.net, fstests@vger.kernel.org, jaegeuk@kernel.org References: <20260622070438.1542638-1-jprusakowski@google.com> Content-Language: en-US Autocrypt: addr=chao@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Christoph, On 7/20/26 16:04, Christoph Hellwig wrote: > So looking at this explanation and the code, f2fs does not actually > support COLLAPSE_RANGE at all, but emulates by doing a full data For non-checkpoint data, we can just update metadata w/o any data copying to support COLLAPSE_RANGE. > copy. What is the point of this and lying to the user that it supports > and operation that isn't actually supported as the intended metadata > only swizzle? I added the fcollapse support long time ago in commit b4ace3370324 ("f2fs: support FALLOC_FL_COLLAPSE_RANGE"), and then, a following patch was committed to fix checkpoint case by copying data. IIRC, the intention at that time is trying to support modern filesystem features as many as possible, so while commercializing f2fs filesystem, it won't break userspace application use if previous filesystem support the feature. I just followed manual of fallocate 2 to implement the fcollapse, I didn't notice fcollapse is a metadata operation only interface, but I may missed something in manual or discussion conclusion about fcollapse in community, please let me know if I missed something. :) Thanks,