Date: Wed, 06 Aug 2025 17:55:26 +0200 From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@FreeBSD.org> To: Rick Macklem <rick.macklem@gmail.com> Cc: FreeBSD CURRENT <freebsd-current@freebsd.org> Subject: Re: RFC: Does ZFS block cloning do this? Message-ID: <86bjos5tsh.fsf@ltc.des.dev> In-Reply-To: <CAM5tNy7V7Btem%2ByWNK7oyn9qsk6TrQwuGo1kxqhCstLM4_uh9g@mail.gmail.com> (Rick Macklem's message of "Wed, 6 Aug 2025 08:17:10 -0700") References: <CAM5tNy7V7Btem%2ByWNK7oyn9qsk6TrQwuGo1kxqhCstLM4_uh9g@mail.gmail.com>
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Rick Macklem <rick.macklem@gmail.com> writes: > NFSv4.2 has a CLONE operation. It is described as doing: > The CLONE operation is used to clone file content from a source file > specified by the SAVED_FH value into a destination file specified by > CURRENT_FH without actually copying the data, e.g., by using a > copy-on-write mechanism. > [...] > Does ZFS block cloning do this? The question you should be asking is “does FreeBSD currently provide something that could be used to implement this” and the answer is VOP_COPY_FILE_RANGE(9). It will copy the data if the underlying filesystem does not provide a no-copy mechanism or if that mechanism can't be used (e.g. the files are in different pools), but it shouldn't be difficult to add a flag; calling VOP_COPY_FILE_RANGE() with that flag would implement intra-server CLONE, and calling it without the flag would implement intra-server COPY. Note that VOP_COPY_FILE_RANGE() does not always copy the entire file in a single operation; you will have to call it in a loop until len is zero or an error occurs. DES -- Dag-Erling Smørgrav - des@FreeBSD.orghelp
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