Re: [bug #17877] Invalid "No such file or directory" error on filesystem without stable inode numbers

[Paul Eggert]

Miklos Szeredi <address@hidden> writes:

>> If files are identified by the path, then you can hash the
>> path. If you use a good 64-bit hash the chance of collision
>> is practically zero. That's good enough.
>
> Yes.  And this solution is actually practical on pure 64bit
> archs only.  On 32bit and dual archs it's not practial, because
> legacy apps (those compiled without largefile support)

First, we're not talking about legacy apps here.  The applications
we're talking about all have largefile support, as do the vast
majority of other applications that I use daily.  So if you come up
with a solution that works well with largefile apps, and does
something sort-of-reasonable for legacy apps, that's fine.

Second, even 32-bit hashes are pretty good.  The chances of their
screwing up in practice are quite small, if you have good hash
functions.

> This is not a theoretical
> possibility, I've had bug reports in this area.

If it's for legacy apps, tell people to recompile with largefile
support.  That's much better than asking people to rewrite thousands
of apps.  (If you're getting lots of bug reports for legacy apps, then
improve the quality of your 32-bit hash functions.  :-)

> Currently I have report of exactly 1 (one) application,
> that breaks.

Sorry, that's not sufficient evidence.  I'm sure lots of other apps
will break, but people won't necessarily know where to send the bug
reports.

There is a standard for this, a standard that reflects longstanding
practice.  Just conform to the standard, and you'll be fine.