Re: [PATCH] eventfs: Have inodes have unique inode numbers

Matthew Wilcox
2024-01-26T23:04:38Z

On Fri, Jan 26, 2024 at 02:48:45PM -0800, Linus Torvalds wrote:
> On Fri, 26 Jan 2024 at 14:34, Matthew Wilcox <willy@infradead.org> wrote:
> >
> > On Fri, Jan 26, 2024 at 05:14:12PM -0500, Mathieu Desnoyers wrote:
> > > I would suggest this straightforward solution to this:
> > >
> > > a) define a EVENTFS_MAX_INODES (e.g. 4096 * 8),
> > >
> > > b) keep track of inode allocation in a bitmap (within a single page),
> > >
> > > c) disallow allocating more than "EVENTFS_MAX_INODES" in eventfs.
> >
> > ... reinventing the IDA?
>
> Guysm, this is a random number that is *so* interesting that I
> seriously think we shouldn't have it at all.
>
> End result: nobody should care. Even the general VFS layer doesn't care.
>
> It literally avoids inode number zero, not because it would be a bad
> inode number, but simply because of some random historical oddity.
>
> In fact, I don't think we even have a reason for it. We have a commit
> 2adc376c5519 ("vfs: avoid creation of inode number 0 in get_next_ino")
> and that one calls out glibc for not deleting them. That makes no
> sense to me, but whatever.

Maybe we should take advantage of that historical oddity. All files
in eventfs have inode number 0, problem solved.