Messages in this thread | | | Date | Wed, 12 Aug 2020 16:08:07 +0100 | From | Al Viro <> | Subject | Re: file metadata via fs API (was: [GIT PULL] Filesystem Information) |
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On Wed, Aug 12, 2020 at 04:46:20PM +0200, Miklos Szeredi wrote:
> > "Can those suckers be passed to > > ...at() as starting points? > > No.
Lovely. And what of fchdir() to those? Are they all non-directories? Because the starting point of ...at() can be simulated that way...
> > Can they be bound in namespace? > > No. > > > Can something be bound *on* them? > > No. > > > What do they have for inodes > > and what maintains their inumbers (and st_dev, while we are at > > it)? > > Irrelevant. Can be some anon dev + shared inode. > > The only attribute of an attribute that I can think of that makes > sense would be st_size, but even that is probably unimportant. > > > Can _they_ have secondaries like that (sensu Swift)? > > Reference?
http://www.online-literature.com/swift/3515/ So, naturalists observe, a flea Has smaller fleas that on him prey; And these have smaller still to bite 'em, And so proceed ad infinitum. of course ;-) IOW, can the things in those trees have secondary trees on them, etc.? Not "will they have it in your originally intended use?" - "do we need the architecture of the entire thing to be capable to deal with that?"
> > Is that a flat space, or can they be directories?" > > Yes it has a directory tree. But you can't mkdir, rename, link, > symlink, etc on anything in there.
That kills the "shared inode" part - you'll get deadlocks from hell that way. "Can't mkdir" doesn't save you from that. BTW, what of unlink()? If the tree shape is not a hardwired constant, you get to decide how it's initially populated...
Next: what will that tree be attached to? As in, "what's the parent of its root"? And while we are at it, what will be the struct mount used with those - same as the original file, something different attached to it, something created on the fly for each pathwalk and lazy-umounted? And see above re fchdir() - if they can be directories, it's very much in the game.
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