Date: Thu, 31 Aug 2000 09:54:53 +0100 From: David Malone <dwmalone@maths.tcd.ie> To: Bosko Milekic <bmilekic@dsuper.net> Cc: David Malone <dwmalone@maths.tcd.ie>, freebsd-net@FreeBSD.ORG Subject: Re: Proposal to clarify mbuf handling rules Message-ID: <200008310954.aa57200@salmon.maths.tcd.ie> In-Reply-To: Your message of "Wed, 30 Aug 2000 17:44:15 EDT." <Pine.BSF.4.21.0008301739290.10819-100000@jehovah.technokratis.com>
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> But how would you take care of removing a M_RDONLY flag for an mbuf > referring to certain external storage where that one mbuf is not the only > mbuf referring to it? At the time external storage is first attached to a mbuf you can set M_RDONLY if it must never be written to (eg. sendfile bufs or parts of the NFS zero copy stuff might want to do similar). If the M_RDONLY flag is set you must not write to the buffer, otherwise you can write to the buffer if it's a simple mbuf or if the reference count on the external storage is 1. (Atleast, this is the system I had in mind). David. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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