md: raid5: fix clearing of biofill operations

md: raid5: fix clearing of biofill operations

raid5: fix clearing of biofill operations

This is the correct merge of the two upstream patches for this issue (it
was mis-merged...)

ops_complete_biofill() runs outside of spin_lock(&sh->lock) and clears the
'pending' and 'ack' bits.  Since the test_and_ack_op() macro only checks
against 'complete' it can get an inconsistent snapshot of pending work.

Move the clearing of these bits to handle_stripe5(), under the lock.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Joel Bertrand <joel.bertrand@systella.fr>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>