On Wed, Aug 12, 2020 at 5:08 PM Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > 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? Not allowed. > 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?" No. > > > > 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. No. The shared inode is not for lookup, just for the open file. > "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. Why does it have to have a struct mount? It does not have to use dentry/mount based path lookup. Thanks, Miklos
