md/raid5: be more selective about distributing flags across batch.

When a batch of stripes is broken up, we keep some of the flags
that were per-stripe, and copy other flags from the head to all
others.

This only happens while a stripe is being handled, so many of the
flags are irrelevant.

The "SYNC_FLAGS" (which I've renamed to make it clear there are
several) and STRIPE_DEGRADED are set per-stripe and so need to be
preserved.  STRIPE_INSYNC is the only flag that is set on the head
that needs to be propagated to all others.

For safety, add a WARN_ON if others are set, except:
 STRIPE_HANDLE - this is safe and per-stripe and we are going to set
      in several cases anyway
 STRIPE_INSYNC
 STRIPE_IO_STARTED - this is just a hint and doesn't hurt.
 STRIPE_ON_PLUG_LIST
 STRIPE_ON_RELEASE_LIST - It is a point pointless for a batched
           stripe to be on one of these lists, but it can happen
           as can be safely ignored.

Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid5.c

@@ -3534,10 +3534,27 @@ unhash:
 				      struct stripe_head, batch_list);
 		list_del_init(&sh->batch_list);
 
-		set_mask_bits(&sh->state, ~STRIPE_EXPAND_SYNC_FLAG,
-			      head_sh->state & ~((1 << STRIPE_ACTIVE) |
-						 (1 << STRIPE_PREREAD_ACTIVE) |
-						 STRIPE_EXPAND_SYNC_FLAG));
+		WARN_ON_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
+					  (1 << STRIPE_SYNCING) |
+					  (1 << STRIPE_REPLACED) |
+					  (1 << STRIPE_PREREAD_ACTIVE) |
+					  (1 << STRIPE_DELAYED) |
+					  (1 << STRIPE_BIT_DELAY) |
+					  (1 << STRIPE_FULL_WRITE) |
+					  (1 << STRIPE_BIOFILL_RUN) |
+					  (1 << STRIPE_COMPUTE_RUN)  |
+					  (1 << STRIPE_OPS_REQ_PENDING) |
+					  (1 << STRIPE_DISCARD) |
+					  (1 << STRIPE_BATCH_READY) |
+					  (1 << STRIPE_BATCH_ERR) |
+					  (1 << STRIPE_BITMAP_PENDING)));
+		WARN_ON_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
+					      (1 << STRIPE_REPLACED)));
+
+		set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
+					    (1 << STRIPE_DEGRADED)),
+			      head_sh->state & (1 << STRIPE_INSYNC));
+
 		sh->check_state = head_sh->check_state;
 		sh->reconstruct_state = head_sh->reconstruct_state;
 		for (i = 0; i < sh->disks; i++) {
@@ -3549,7 +3566,7 @@ unhash:
 		spin_lock_irq(&sh->stripe_lock);
 		sh->batch_head = NULL;
 		spin_unlock_irq(&sh->stripe_lock);
-		if (sh->state & STRIPE_EXPAND_SYNC_FLAG)
+		if (sh->state & STRIPE_EXPAND_SYNC_FLAGS)
 			set_bit(STRIPE_HANDLE, &sh->state);
 		release_stripe(sh);
 	}
@@ -3559,7 +3576,7 @@ unhash:
 	spin_unlock_irq(&head_sh->stripe_lock);
 	if (wakeup_nr)
 		wake_up(&conf->wait_for_overlap);
-	if (head_sh->state & STRIPE_EXPAND_SYNC_FLAG)
+	if (head_sh->state & STRIPE_EXPAND_SYNC_FLAGS)
 		set_bit(STRIPE_HANDLE, &head_sh->state);
 }
 
@@ -4246,11 +4263,27 @@ static void break_stripe_batch_list(struct stripe_head *head_sh,
 
 		list_del_init(&sh->batch_list);
 
-		set_mask_bits(&sh->state, ~STRIPE_EXPAND_SYNC_FLAG,
-			      head_sh->state & ~((1 << STRIPE_ACTIVE) |
-						 (1 << STRIPE_PREREAD_ACTIVE) |
-						 (1 << STRIPE_DEGRADED) |
-						 STRIPE_EXPAND_SYNC_FLAG));
+		WARN_ON_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
+					  (1 << STRIPE_SYNCING) |
+					  (1 << STRIPE_REPLACED) |
+					  (1 << STRIPE_PREREAD_ACTIVE) |
+					  (1 << STRIPE_DELAYED) |
+					  (1 << STRIPE_BIT_DELAY) |
+					  (1 << STRIPE_FULL_WRITE) |
+					  (1 << STRIPE_BIOFILL_RUN) |
+					  (1 << STRIPE_COMPUTE_RUN)  |
+					  (1 << STRIPE_OPS_REQ_PENDING) |
+					  (1 << STRIPE_DISCARD) |
+					  (1 << STRIPE_BATCH_READY) |
+					  (1 << STRIPE_BATCH_ERR) |
+					  (1 << STRIPE_BITMAP_PENDING)));
+		WARN_ON_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
+					      (1 << STRIPE_REPLACED)));
+
+		set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
+					    (1 << STRIPE_DEGRADED)),
+			      head_sh->state & (1 << STRIPE_INSYNC));
+
 		sh->check_state = head_sh->check_state;
 		sh->reconstruct_state = head_sh->reconstruct_state;
 		for (i = 0; i < sh->disks; i++) {

drivers/md/raid5.h

@@ -342,7 +342,7 @@ enum {
 				 */
 };
 
-#define STRIPE_EXPAND_SYNC_FLAG \
+#define STRIPE_EXPAND_SYNC_FLAGS \
 	((1 << STRIPE_EXPAND_SOURCE) |\
 	(1 << STRIPE_EXPAND_READY) |\
 	(1 << STRIPE_EXPANDING) |\