Date: Mon, 27 Apr 2009 13:23:39 +0200 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-fs@freebsd.org Subject: Re: UFS2 metadata checksums Message-ID: <gt44jt$vl5$1@ger.gmane.org> In-Reply-To: <49F42786.6070008@bqinternet.com> References: <49F048FB.6000401@bqinternet.com> <20090423195335.521db0a7@kan.dnsalias.net> <49F16009.3080206@bqinternet.com> <gst2ct$t35$1@ger.gmane.org> <49F42786.6070008@bqinternet.com>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig846BEF3A81E86FCB5A3D385C Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Scott Burns wrote: > Ivan Voras wrote: >> Scott Burns wrote: >> >>> As long as there is some interest in this kind of functionality, I wi= ll >>> continue working on it. The next step is to protect metadata structu= res >>> beyond inodes. I am hoping to have some results to post in the next = few >>> weeks. >> >> Btw. what checksum do you use? >=20 > I haven't settled on anything yet. Currently I'm just reading the > dinode structure 32 bits at a time and doing a bitwise XOR. It's just = a > proof of concept and I am open to suggestions. For 32 bits of hash, adler32 or crc32 should be ok - the code is already used in the system for various purposes. Adler32 is faster; for a sample implementation see sys/net/zlib.c at line 5357. ZFS defaults to "fletcher2" (I guess 16-bit Fletcher?) which should be faster but its implementation could be a bit problematic (see http://opensolaris.org/jive/thread.jspa?threadID=3D69655&tstart=3D0). --------------enig846BEF3A81E86FCB5A3D385C Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFJ9ZXCldnAQVacBcgRAsARAJ0RFwItqrsPcC5+jKVs4LnJeHV9PACeKMzy dvgDWFrhWQ7U8NWRjLMyEWo= =lFbm -----END PGP SIGNATURE----- --------------enig846BEF3A81E86FCB5A3D385C--
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