Date: Sun, 9 Dec 2007 22:14:33 +0100 From: Karsten Behrmann <BearPerson@gmx.net> To: freebsd-hackers@freebsd.org Subject: Re: unionfs & kqueue? Message-ID: <20071209221433.216218d7@Karsten.Behrmanns.Kasten> In-Reply-To: <fjhi8o$trn$1@ger.gmane.org> References: <fjhi8o$trn$1@ger.gmane.org>
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--Sig_qCfLlgaMlXqmI5rVZAy9BR8 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Heya, > Does unionfs work with kqueue? When I run `tail -f` on a file residing > on unionfs with cd9660 underneeth and md+ufs over it, it doesn't detect > changes. The changes are immediately visible, just not with tail -f. Hmm. When you start the tail -f, does the file reside on the cd9660 or already on the md? See if tail -F does a better job. My guess would be that, since you cannot modify a file on any filesystem except the top one, unionfs must change semantics of open so that even opening for writing or appending silently creates a new copy of the file on the top filesystem (if the file didn't reside there already). As tail -f still has the lower-layer file open, it never notices that there's a new file by the name. (this behavior is the same as echo foo >foo tail -f foo # in another terminal echo bar >bar mv bar foo which also "fails" to notice the new data) So Far, Karsten "BearPerson" Behrmann p.s.: this is probably why the -F option was added to tail --=20 Open source is not about suing someone who sells your software. It is about being able to walk behind him, grinning, and waving free CDs with the equivalent of what he is trying to sell. --Sig_qCfLlgaMlXqmI5rVZAy9BR8 Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (GNU/Linux) iD8DBQFHXFq8AksKLoO3vywRAktuAJ0a8m5P4GRw+EylQyUQloyMQwe3nwCeK5Ys qJbIV9IH8DFmKDjzuUCuDO4= =ZZDb -----END PGP SIGNATURE----- --Sig_qCfLlgaMlXqmI5rVZAy9BR8--
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