On Mon, 21 Jan 2008, Linus Torvalds wrote: > > Think about the file name "Abc", and think about what happens when you > create it. > > Now, think about what happens if that filename is considered equivalent in > case.. > > See? The filesystem has to *corrupt* the filename. Let me make this really clear, because I'm afraid that you won't get it when I leave out any steps of the way. Let us say that there is a filename "xyz" that is equivalent to a filename "abc" in *any* way. It does not matter if xyz/abc is Hello/hello, or whether it's two canonically equivalent strings. So now, do close(open(xyz, O_WRONLY | O_CREAT, 0666)); close(open(abc, O_WRONLY | O_CREAT, 0666)); and then look at the directory contents afterwards. There are two, and only two, choices here (*): - the filesystem created both files, and they show up as created - the filesystem decided they were equivalent, and munged one (or both) of them Now, let's go back to my claim: - munging user data is unacceptable and realize that equivalence BY DEFINITION must do it. So no, you do *not* get to have your cake and eat it too. You simply fundamentally *cannot* have both filename equivalence and a non-munging filesystem. See above why. Linus (*) Actually, there is third choice above, which is: - the filesystem created the first file, and errored out on the second because it noticed it was equivalent - but not identical - to one it already had This one is actually a perfectly fine choice, but it's not "your" kind of equivalence, since it actually makes a difference between two equivalent but non-identical names. So the filenames aren't actually interchangable, and this case is really more of a "the filesystem has some very specific limitations on what it allows". - To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
