Re: [PATCH 2/2] vfs: force reval on dentry of bind mounted files on FS_REVAL_DOT filesystems

[Miklos Szeredi]

On Thu, 03 Dec 2009, Eric W. Biederman wrote:
> > The only worry I have is that this adds an extra branch in a very hot
> > codepath (do_lookup).  An error can't be returned, as you note, and
> > for bind mounted directories d_invalidate() will not succeed: the
> > directory is busy, it's referenced by the mount. 
> 
> Not true.  d_mountpoint is false, so d_invalidate can succeed.

Have a look at the code.  d_invalidate() doesn't check for a
mountpoint, it checks the refcount.  It needs to keep the directory
dentry hashed if it's in any way reachable other than from the cache
(file descriptor, cwd, mount, etc).

Thanks,
Miklos
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