Messages in this thread | | | From | Miklos Szeredi <> | Date | Tue, 11 Aug 2020 20:49:35 +0200 | Subject | Re: file metadata via fs API (was: [GIT PULL] Filesystem Information) |
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On Tue, Aug 11, 2020 at 6:05 PM Linus Torvalds <torvalds@linux-foundation.org> wrote:
> and then people do "$(srctree)/". If you haven't seen that kind of > pattern where the pathname has two (or sometimes more!) slashes in the > middle, you've led a very sheltered life.
Oh, I have. That's why I opted for triple slashes, since that should work most of the time even in those concatenated cases. And yes, I know, most is not always, and this might just be hiding bugs, etc... I think the pragmatic approach would be to try this and see how many triple slash hits a normal workload gets and if it's reasonably low, then hopefully that together with warnings for O_ALT would be enough.
> (b) even if the new user space were to think about that, and remove > those (hah! when have you ever seen user space do that?), as Al > mentioned, the user *filesystem* might have pathnames with double > slashes as part of symlinks. > > So now we'd have to make sure that when we traverse symlinks, that > O_ALT gets cleared.
That's exactly what I implemented in the proof of concept patch.
> Which means that it's not a unified namespace > after all, because you can't make symlinks point to metadata.
I don't think that's a great deal. Also I think other limitations would make sense:
- no mounts allowed under /// - no ./.. resolution after /// - no hardlinks - no special files, just regular and directory - no seeking (regular or dir)
> cat my-file.tar/inside/the/archive.c > > or similar. > > Al has convinced me it's a horrible idea (and there you have a > non-ambiguous marker: the slash at the end of a pathname that > otherwise looks and acts as a non-directory)
Umm, can you remind me what's so horrible about that? Yeah, hard linked directories are a no-no. But it doesn't have to be implemented in a way to actually be a problem with hard links.
Thanks, Miklos
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