Date: Wed, 19 Oct 2005 20:03:27 +0200 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Szalai Andras <andrew@djw.hu> Cc: freebsd-geom@freebsd.org Subject: Re: geom orphan question Message-ID: <5675.1129745007@critter.freebsd.dk> In-Reply-To: Your message of "Wed, 19 Oct 2005 19:53:10 %2B0200." <20051019175310.GC76081@web.djw.hu>
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In message <20051019175310.GC76081@web.djw.hu>, Szalai Andras writes: >I have spent few hours trying to understand geom. The I/O >path is more or less okay, but I have problems with >the orphanization procedure. > >For example, if you look into g_concat.c there is a >g_concat_orphan function that calls g_concat_remove_disk. >In this function, gconcat > >1) orphans its own provider (g_orphan_provider), >2) reset access counts (g_access), >3) detach consumer from the lower layer provider, >4) destroy the consumer. > >In order to detach the consumer (step 3) you have to be sure >that there are no active requests (bios) between the consumer and >provider. My question is how can I guarantee that there are >no active bios when I call g_detach? There are counters in consumers and providers which can tell you that. The above code seems to play fast and loose with that aspect. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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