md: ensure all blocks are uptodate or locked when syncing

Remove the dubious attempt to prefer 'compute' over 'read'.  Not only is it
wrong given commit c337869d (md: do not compute parity unless it is on a failed
drive), but it can trigger a BUG_ON in handle_parity_checks5().

Cc: <stable@kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Neil Brown <neilb@suse.de>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 54c8ee2..3b27df5 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2017,12 +2017,7 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh,
                         */
                        s->uptodate++;
                        return 0; /* uptodate + compute == disks */
-               } else if ((s->uptodate < disks - 1) &&
-                       test_bit(R5_Insync, &dev->flags)) {
-                       /* Note: we hold off compute operations while checks are
-                        * in flight, but we still prefer 'compute' over 'read'
-                        * hence we only read if (uptodate < * disks-1)
-                        */
+               } else if (test_bit(R5_Insync, &dev->flags)) {
                        set_bit(R5_LOCKED, &dev->flags);
                        set_bit(R5_Wantread, &dev->flags);
                        if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))