Messages in this thread | | | Date | Fri, 01 Jul 2005 03:27:28 -0500 | From | David Masover <> | Subject | Re: reiser4 plugins |
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Hans Reiser wrote: > It was always the expectation that users would want to have one > mountpoint with the files having metafiles as files, and another with > the same files but strictly posix, and then their apps can use whichever > they have the power to understand.
It was never in the early betas I tried :(
I'm proposing (or re-proposing) that the /meta mountpoint be strictly for accessing meta-files, with no intention of eventually using this by default. Furthermore, /meta should follow POSIX anyway, mostly -- no file-as-dir there, either, although you still wouldn't want to use tar on it.
With only a few patches, using /meta could be almost as convenient as using file/..metas/foo, and it completely kills the file-as-directory flamewar -- everybody's happy.
Or so I thought. It seems that the people arguing for file-as-directory are ignoring /meta, and the people arguing against it are arguing against all meta-files, saying that the good things about meta-files don't justify the risks of file-as-dir. Only once did I see someone bring up /meta.
I don't like the idea of having /meta have file-as-dir and everything as we originally wanted, because then we've duplicated the interface. To read the *contents* of /foo, I can either cat /foo or cat /meta/foo. I'd hate to have the POSIX mountpoint still lying around if no one's using it, even more than I hate the idea of "foo" being in two places for no good reason.
Is there a technical (performance?) reason that my approach is wrong? (metas go in /meta, files go in /, and everything feels POSIX-y)
> Hans > > David Masover wrote: > > >>Hubert Chan wrote: >> >> >>>On Wed, 29 Jun 2005 17:34:41 -0400, Ross Biro <ross.biro@gmail.com> >>>said: >>> >>> >>> >>>>I'm confused. Can someone on one of these lists enlighten me? >>> >>> >>> >>>>How is directories as files logically any different than putting all >>>>data into .data files and making all files directories (yes you would >>>>need some sort of special handling for files that were really called >>>>.data). Then it's just a matter of deciding what happens when you >>>>call open and stat on one of these files? >>> >>> >>> >>>Logically, I don't think there is a difference. A filesystem that >>>doesn't support file-as-dir could implement the same functionality that >>>way. [1] In fact, that's essentially what MacOS X/NeXTSTEP does with >>>its >>>bundle format -- it's just a regular directory with regular files >>>inside. >> >> >>I, personally, would hate it if everything in my /bin suddenly became >>a directory, mainly because everything would stop working. Is that >>the kind of thing you're suggesting? >> >>I'm a little confused about the .data idea, I guess. >> >> >>>>But we could have a whole new set of system calls that treat things as >>>>magic, and if files as directories is as cool as many people think, >>>>apps will start using the new api. If not, they won't and the new api >>>>can be deprecated. >>> >>> >>> >>>File-as-dir doesn't require new system calls (that I know of), which is >>>the whole point of the idea. Existing programs can edit the strange new >>>attributes without being modified. >> >> >>That is indeed the point, but scroll down. >> >> >>>The main thing blocking file-as-dir is that there are some >>>locking(IIRC?) issues. And, of course, some people wouldn't want it to >>>be merged into the mainline kernel. (Of course, the latter doesn't >>>prevent Namesys from maintaining their own patches for people to play >>>around with.) >> >> >>What's the locking issue? I think that was more about transactions... >> >>[...] >> >> >>>People like Horst (and probably others, who are less vocal), I think, >>>don't think that it's even worth trying it out because they don't see >>>any major advantages. Or at least they think that the potential >>>negatives outweigh the potential positives. I respect that they have >>>different opinions, but I of course disagree and attempt to convince >>>them otherwise. >> >> >>Did the /meta (metafs) idea get killed while I was out? Using that >>approach, your potential negatives are that apps which crawl the >>entire FS tree, starting at /, with hardcoded apps for /proc and /sys, >>are now broken -- but then, /sys already broke them once, so I don't >>particularly care if we break them again. >> >>Potential positives? I think even just because we like the idea is >>enough, because it doesn't break anything and doesn't really affect >>anyone who doesn't use it. >> >>Maybe there are coding standards, but I think others are working that >>out now. >> >> > >
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