Date: Sat, 3 Oct 1998 01:36:42 +0200 From: Eivind Eklund <eivind@yes.no> To: Don Lewis <Don.Lewis@tsc.tdk.com>, Terry Lambert <tlambert@primenet.com> Cc: freebsd-fs@FreeBSD.ORG Subject: Re: vm system interaction with nullfs Message-ID: <19981003013642.65347@follo.net> In-Reply-To: <19981002131152.26322@follo.net>; from Eivind Eklund on Fri, Oct 02, 1998 at 01:11:52PM %2B0200 References: <tlambert@primenet.com> <199810020933.CAA15261@salsa.gv.tsc.tdk.com> <19981002131152.26322@follo.net>
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On Fri, Oct 02, 1998 at 01:11:52PM +0200, Eivind Eklund wrote: > On Fri, Oct 02, 1998 at 02:33:42AM -0700, Don Lewis wrote: > > } The general fix is to create a "getfinalvp". This would allow you > > } to page through an object, while allowing layers stacked on top to > > } dictate layout/content. > > > > I started down this path and created VOP_GETBACKINGVP. This part was > > pretty easy. The problem is that there are a zillion references to > > vp->v_object all over the place that would need to be fixed. > > "A zillion" == 63. Interesting. I've always wondered what exact > number it represents :-) > > Fixing these are trivial. I can do that in (much) less than an hour, > if there is general agreement that this is the way to go (I think it > sound reasonable). OK, it took a couple of hours. There is a set of patches to introduce VOP_GETBACKINGOBJECT() at http://www.freebsd.org/~eivind/ - these are absolutely non-tested (ie, they compile, but I have not even tried booting the kernel they produce). They are there only in case somebody want to see the scope changes required to do this. I'm not sure how much better off we're with this, however - there seems to be some cases that still might be impossible to get right, e.g. if we want to split a vm object over two vnodes (to have a file-by-file RAID-1). I'll have to think a bit more before I know which direction to pull. Eivind. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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