Re: iov_iter_pipe warning.

[Al Viro]

On Sat, Sep 09, 2017 at 09:07:56PM -0400, Dave Jones wrote:

> With this in place, I'm still seeing -EBUSY from invalidate_inode_pages2_range
> which doesn't end well...

Different issue, and I'm not sure why that WARN_ON() is there in the
first place.  Note that in a similar situation generic_file_direct_write()
simply buggers off and lets the caller do buffered write...

iov_iter_pipe() warning is a sign of ->read_iter() on pipe-backed iov_iter
putting into the pipe more than it claims to have done.