Date: Mon, 25 Mar 2024 14:59:46 +0100 From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@FreeBSD.org> To: Mark Saad <nonesuch@longcount.org> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: TarFS Message-ID: <86edbyh0od.fsf@ltc.des.dev> In-Reply-To: <CAMXt9NYOA4KJu86gnCwOZeDp31gsxwwrzdb%2Bc6KLsOQxxD6r5A@mail.gmail.com> (Mark Saad's message of "Fri, 22 Mar 2024 11:48:21 -0400") References: <CAMXt9NYOA4KJu86gnCwOZeDp31gsxwwrzdb%2Bc6KLsOQxxD6r5A@mail.gmail.com>
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Mark Saad <nonesuch@longcount.org> writes: > I was wondering if anyone has started to play with tarfs in FreeBSD 14? I wrote it, does that count? > It appears to puke with larger tarballs. On the contrary, one of the use cases I tested was buildworld from a tarball of the source tree, which it handled just fine. > For example, if I fetch a copy of ports or pkgsrc and decompress it to > just a posix tar archive I can't get it to mount. > > root@mono:/home/nonesuch # file ports.tar > ports.tar: POSIX tar archive > root@mono:/home/nonesuch # mount -t tarfs ./ports.tar /tarfs/ports > mount: ./ports.tar: Inappropriate file type or format % fetch ftp://ftp.freebsd.org/pub/FreeBSD/ports/ports/ports.tar.zst ports.tar.zst 47 MB 5431 kBps = 09s % sudo mount -rt tarfs $PWD/ports.tar.zst /mnt mount: /home/des/ports.tar.zst: Inappropriate file type or format % dmesg | grep tarfs=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20 tarfs_alloc_one: unsupported global extended header at 0 % zcat ports.tar.zst | hexdump -C | head -3 00000000 70 61 78 5f 67 6c 6f 62 61 6c 5f 68 65 61 64 65 |pax_global_hea= de| 00000010 72 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |r.............= ..| 00000020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |..............= ..| This is a non-standard extension header emitted by `git archive` which contains metadata about the git tree from which the archive was created. I believe you can safely strip it off (zcat ports.tar.zst | dd bs=3D1k skip=3D1 >ports.tar), but you'll run into issues with very long paths in devel/electron*. I will take a closer look when I find the time. Note that tarfs can mount tarballs compressed with zstd, but performance will be poor unless you create a multi-frame archive (try using --zstd --options=3Dzstd:frame-per-file,zstd:min-frame-size=3D65536). DES --=20 Dag-Erling Sm=C3=B8rgrav - des@FreeBSD.org
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