Re: [RFC PATCH 2/3] vfs: add d_replace()

On Tue, Nov 22, 2016 at 12:25:02AM -0800, Omar Sandoval wrote:

From: Omar Sandoval <redacted>

Changes the inode associated with a dentry. This'll be useful for
implementations of linkat() AT_REPLACE.

Hard NAK.  That violates all kinds of assumptions made by VFS and
filesystems alike; never, ever do that.  If you have a reference to
a positive dentry, inode should *NEVER* change.

If it unhashed the old dentry, created a new one and attached inode to
it, it _might_ have a chance.  I'm less than sure it's a good idea, but
it this form it's a non-starter.

Again,

NAKed-by: Al Viro [off-list ref]

and don't bring it back in that form.