Date: Thu, 25 Jan 2001 20:00:18 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: adrian@freebsd.org (Adrian Chadd) Cc: tlambert@primenet.com (Terry Lambert), freebsd-arch@freebsd.org Subject: Re: mount options Message-ID: <200101252000.NAA26572@usr08.primenet.com> In-Reply-To: <20010124085920.A2795@roaming.cacheboy.net> from "Adrian Chadd" at Jan 24, 2001 08:59:21 AM
next in thread | previous in thread | raw e-mail | index | archive | help
> I'll reply to this snippet now, and the rest later today.. > > > > For an FS porting project I'm doing, the mount interface needs > > > to be able to export the mount options back out to userspace, > > > and I'd like to tidy the code up instead of just fudge it for > > > my needs. > > > > The bitmap would be ideal for this. The only arguments which > > would not fall into this are the "what you are mounting" and > > the "where you are mounting it" arguments, which will have to > > be handled seperately, in any case. > > The trouble is that the mount options aren't always going to be > flags which are on or off. They *could* be say, a log device for > seperate FS logging. This doesn't fit inside a bitmap, and I'd have > to have to hack together a seperate sysctl or something just to get > information for this particular FS. I still say parametric data belongs in the superblock or other metadata structure. You change it via "newfs" or "tunefs". The main thing to consider, I think, is that string processing really doesn't belong in the kernel. We are stuck with path component processing, not because we are really stuck with it (like we would be if we had globbing in the kernel), but because the design of the VFS stacking permits an underlying VFS to eat multiple path components. Personally, as far as component processing goes, I like the idea of a path component descriptor list far more than a string anyway, but we'd have to fix the lookup mutual recursion for this to work. That basically leaves sysctl and mount as aggregious examples of string passing and processing that shouldn't be there. Like I said, that's my two cents worth. For four cents worth, we should really think about doing globbing in the kernel, if we are going to be passing strings down, since it's a much, much bigger win to not pass useless data back across the user/kernel boundary if someone is, for example, looking for a list of directories. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200101252000.NAA26572>