dax: alloc_dax() return ERR_PTR(-EOPNOTSUPP) for CONFIG_DAX=n

Change the return value from NULL to PTR_ERR(-EOPNOTSUPP) for
CONFIG_DAX=n to be consistent with the fact that CONFIG_DAX=y
never returns NULL.

This is done in preparation for using cpu_dcache_is_aliasing() in a
following change which will properly support architectures which detect
data cache aliasing at runtime.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 4e4ced93794a ("dax: Move mandatory ->zero_page_range() check in alloc_dax()")
Signed-off-by: Mathieu Desnoyers <[email protected]>
Reviewed-by: Dan Williams <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Vishal Verma <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Russell King <[email protected]>
Cc: Alasdair Kergon <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: kernel test robot <[email protected]>
Cc: Michael Sclafani <[email protected]>
Cc: Mike Snitzer <[email protected]>
Cc: Mikulas Patocka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions