XArray: Fix infinite loop with entry at ULONG_MAX

If there is an entry at ULONG_MAX, xa_for_each() will overflow the
'index + 1' in xa_find_after() and wrap around to 0.  Catch this case
and terminate the loop by returning NULL.

Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Cc: [email protected]
2 files changed