+ /* Now we check to see if any write operations have recently
+ * completed
+ */
+
+ /* leave prexor set until postxor is done, allows us to distinguish
+ * a rmw from a rcw during biodrain
+ */
+ if (test_bit(STRIPE_OP_PREXOR, &sh->ops.complete) &&
+ test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
+
+ clear_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
+ clear_bit(STRIPE_OP_PREXOR, &sh->ops.ack);
+ clear_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
+
+ for (i = disks; i--; )
+ clear_bit(R5_Wantprexor, &sh->dev[i].flags);
+ }
+
+ /* if only POSTXOR is set then this is an 'expand' postxor */
+ if (test_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete) &&
+ test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
+
+ clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
+ clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.ack);
+ clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
+
+ clear_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
+ clear_bit(STRIPE_OP_POSTXOR, &sh->ops.ack);
+ clear_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
+
+ /* All the 'written' buffers and the parity block are ready to
+ * be written back to disk
+ */
+ BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags));
+ for (i = disks; i--; ) {
+ dev = &sh->dev[i];
+ if (test_bit(R5_LOCKED, &dev->flags) &&
+ (i == sh->pd_idx || dev->written)) {
+ pr_debug("Writing block %d\n", i);
+ set_bit(R5_Wantwrite, &dev->flags);
+ if (!test_and_set_bit(
+ STRIPE_OP_IO, &sh->ops.pending))
+ sh->ops.count++;
+ if (!test_bit(R5_Insync, &dev->flags) ||
+ (i == sh->pd_idx && s.failed == 0))
+ set_bit(STRIPE_INSYNC, &sh->state);
+ }
+ }
+ if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
+ atomic_dec(&conf->preread_active_stripes);
+ if (atomic_read(&conf->preread_active_stripes) <
+ IO_THRESHOLD)
+ md_wakeup_thread(conf->mddev->thread);
+ }
+ }
+
+ /* Now to consider new write requests and what else, if anything
+ * should be read. We do not handle new writes when:
+ * 1/ A 'write' operation (copy+xor) is already in flight.
+ * 2/ A 'check' operation is in flight, as it may clobber the parity
+ * block.
+ */
+ if (s.to_write && !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending) &&
+ !test_bit(STRIPE_OP_CHECK, &sh->ops.pending))