Messages in this thread | | | Date | Wed, 29 May 2013 10:12:12 +0200 | Subject | Re: [RFC PATCH] vfs: add permute operation | From | Miklos Szeredi <> |
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On Tue, May 28, 2013 at 7:36 PM, Zach Brown <zab@redhat.com> wrote: > Some quick thoughts: > >> Permute the location of files. E.g. 'permute(A, B, C)' is equivalent to A->B, >> B->C and C->A. This is essentially a series of renames done as a single atomic >> operation. > > Hmm. Can we choose a more specific name than 'permute'? To me, > ->permute() tells me just as much about the operation as > ->do_something(). {multi,bulk,mass}_rename()? renamev()?
It's not just plain muti-rename, but a cyclic one. Maybe cyclic_rename()?
>> +static void sort_parents3(struct dentry **p) >> +void sort_parents(struct dentry **p, unsigned *nump) > > Yikes, that's a bunch of fiddly code. Is it *really* worth all that to > avoid calling the generic sort helpers?
AFAICS, I cannot make the compare function transitive, e.g.: A is descendant of C but B is unrelated. Then what should cmp(A, B) and cmp(B, C) return?
> >> + if (WARN_ON(num > PERMUTE_MAX) || >> + WARN_ON(num < 2)) >> + return -EINVAL; > > And in other places this is a BUG? Why not, like the syscall, limit the > arguments to three if we're serious about that limitation?
I could be more consistent with the BUGs. Doing it with 3 args is not necessarily good, since then we can't do loops and the chance of a copy-paste error is increased.
Thanks, Miklos
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