[PATCH] xfs: don't perform lookups on zero-height btrees

[Christoph Hellwig]

On Fri, Aug 19, 2016 at 01:30:22PM -0700, Darrick J. Wong wrote:
> If the caller passes in a cursor to a zero-height btree (which is
> impossible), we never set block to anything but NULL, which causes the
> later dereference of it to crash.  Instead, just return -EFSCORRUPTED.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>

Looks fine,

Reviewed-by: Christoph Hellwig <hch at lst.de>

maybe also throw in an unlikely notation, though..