md/raid5: unify stripe_head_state and r6_state

'struct stripe_head_state' stores state about the 'current' stripe
that is passed around while handling the stripe.
For RAID6 there is an extension structure: r6_state, which is also
passed around.
There is no value in keeping these separate, so move the fields from
the latter into the former.

This means that all code now needs to treat s->failed_num as an small
array, but this is a small cost.

Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Namhyung Kim <namhyung@gmail.com>

drivers/md/raid5.c

@@ -2318,7 +2318,7 @@ static int fetch_block5(struct stripe_head *sh, struct stripe_head_state *s,
 			int disk_idx, int disks)
 {
 	struct r5dev *dev = &sh->dev[disk_idx];
-	struct r5dev *failed_dev = &sh->dev[s->failed_num];
+	struct r5dev *failed_dev = &sh->dev[s->failed_num[0]];
 
 	/* is the data in this block needed, and can we get it? */
 	if (!test_bit(R5_LOCKED, &dev->flags) &&
@@ -2334,7 +2334,7 @@ static int fetch_block5(struct stripe_head *sh, struct stripe_head_state *s,
 		 * otherwise read it if the backing disk is insync
 		 */
 		if ((s->uptodate == disks - 1) &&
-		    (s->failed && disk_idx == s->failed_num)) {
+		    (s->failed && disk_idx == s->failed_num[0])) {
 			set_bit(STRIPE_COMPUTE_RUN, &sh->state);
 			set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
 			set_bit(R5_Wantcompute, &dev->flags);
@@ -2388,11 +2388,11 @@ static void handle_stripe_fill5(struct stripe_head *sh,
  * 0 to tell the loop in handle_stripe_fill6 to continue
  */
 static int fetch_block6(struct stripe_head *sh, struct stripe_head_state *s,
-			 struct r6_state *r6s, int disk_idx, int disks)
+			int disk_idx, int disks)
 {
 	struct r5dev *dev = &sh->dev[disk_idx];
-	struct r5dev *fdev[2] = { &sh->dev[r6s->failed_num[0]],
-				  &sh->dev[r6s->failed_num[1]] };
+	struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
+				  &sh->dev[s->failed_num[1]] };
 
 	if (!test_bit(R5_LOCKED, &dev->flags) &&
 	    !test_bit(R5_UPTODATE, &dev->flags) &&
@@ -2409,8 +2409,8 @@ static int fetch_block6(struct stripe_head *sh, struct stripe_head_state *s,
 		BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
 		BUG_ON(test_bit(R5_Wantread, &dev->flags));
 		if ((s->uptodate == disks - 1) &&
-		    (s->failed && (disk_idx == r6s->failed_num[0] ||
-				   disk_idx == r6s->failed_num[1]))) {
+		    (s->failed && (disk_idx == s->failed_num[0] ||
+				   disk_idx == s->failed_num[1]))) {
 			/* have disk failed, and we're requested to fetch it;
 			 * do compute it
 			 */
@@ -2465,7 +2465,7 @@ static int fetch_block6(struct stripe_head *sh, struct stripe_head_state *s,
  * handle_stripe_fill6 - read or compute data to satisfy pending requests.
  */
 static void handle_stripe_fill6(struct stripe_head *sh,
-			struct stripe_head_state *s, struct r6_state *r6s,
+			struct stripe_head_state *s,
 			int disks)
 {
 	int i;
@@ -2477,7 +2477,7 @@ static void handle_stripe_fill6(struct stripe_head *sh,
 	if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
 	    !sh->reconstruct_state)
 		for (i = disks; i--; )
-			if (fetch_block6(sh, s, r6s, i, disks))
+			if (fetch_block6(sh, s, i, disks))
 				break;
 	set_bit(STRIPE_HANDLE, &sh->state);
 }
@@ -2625,7 +2625,7 @@ static void handle_stripe_dirtying5(raid5_conf_t *conf,
 
 static void handle_stripe_dirtying6(raid5_conf_t *conf,
 		struct stripe_head *sh,	struct stripe_head_state *s,
-		struct r6_state *r6s, int disks)
+		int disks)
 {
 	int rcw = 0, pd_idx = sh->pd_idx, i;
 	int qd_idx = sh->qd_idx;
@@ -2688,7 +2688,7 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
 			s->uptodate--;
 			break;
 		}
-		dev = &sh->dev[s->failed_num];
+		dev = &sh->dev[s->failed_num[0]];
 		/* fall through */
 	case check_state_compute_result:
 		sh->check_state = check_state_idle;
@@ -2760,7 +2760,7 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
 
 static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
 				  struct stripe_head_state *s,
-				  struct r6_state *r6s, int disks)
+				  int disks)
 {
 	int pd_idx = sh->pd_idx;
 	int qd_idx = sh->qd_idx;
@@ -2779,14 +2779,14 @@ static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
 	switch (sh->check_state) {
 	case check_state_idle:
 		/* start a new check operation if there are < 2 failures */
-		if (s->failed == r6s->q_failed) {
+		if (s->failed == s->q_failed) {
 			/* The only possible failed device holds Q, so it
 			 * makes sense to check P (If anything else were failed,
 			 * we would have used P to recreate it).
 			 */
 			sh->check_state = check_state_run;
 		}
-		if (!r6s->q_failed && s->failed < 2) {
+		if (!s->q_failed && s->failed < 2) {
 			/* Q is not failed, and we didn't use it to generate
 			 * anything, so it makes sense to check it
 			 */
@@ -2828,13 +2828,13 @@ static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
 		 */
 		BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
 		if (s->failed == 2) {
-			dev = &sh->dev[r6s->failed_num[1]];
+			dev = &sh->dev[s->failed_num[1]];
 			s->locked++;
 			set_bit(R5_LOCKED, &dev->flags);
 			set_bit(R5_Wantwrite, &dev->flags);
 		}
 		if (s->failed >= 1) {
-			dev = &sh->dev[r6s->failed_num[0]];
+			dev = &sh->dev[s->failed_num[0]];
 			s->locked++;
 			set_bit(R5_LOCKED, &dev->flags);
 			set_bit(R5_Wantwrite, &dev->flags);
@@ -2922,7 +2922,7 @@ static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
 }
 
 static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
-				struct r6_state *r6s)
+				    struct stripe_head_state *r6s)
 {
 	int i;
 
@@ -3082,7 +3082,7 @@ static void handle_stripe5(struct stripe_head *sh)
 			clear_bit(R5_Insync, &dev->flags);
 		if (!test_bit(R5_Insync, &dev->flags)) {
 			s.failed++;
-			s.failed_num = i;
+			s.failed_num[0] = i;
 		}
 	}
 	spin_unlock_irq(&conf->device_lock);
@@ -3107,7 +3107,7 @@ static void handle_stripe5(struct stripe_head *sh)
 	pr_debug("locked=%d uptodate=%d to_read=%d"
 		" to_write=%d failed=%d failed_num=%d\n",
 		s.locked, s.uptodate, s.to_read, s.to_write,
-		s.failed, s.failed_num);
+		s.failed, s.failed_num[0]);
 	/* check if the array has lost two devices and, if so, some requests might
 	 * need to be failed
 	 */
@@ -3127,7 +3127,7 @@ static void handle_stripe5(struct stripe_head *sh)
 	     ((test_bit(R5_Insync, &dev->flags) &&
 	       !test_bit(R5_LOCKED, &dev->flags) &&
 	       test_bit(R5_UPTODATE, &dev->flags)) ||
-	       (s.failed == 1 && s.failed_num == sh->pd_idx)))
+	       (s.failed == 1 && s.failed_num[0] == sh->pd_idx)))
 		handle_stripe_clean_event(conf, sh, disks, &return_bi);
 
 	/* Now we might consider reading some blocks, either to check/generate
@@ -3198,11 +3198,11 @@ static void handle_stripe5(struct stripe_head *sh)
 	 * the repair/check process
 	 */
 	if (s.failed == 1 && !conf->mddev->ro &&
-	    test_bit(R5_ReadError, &sh->dev[s.failed_num].flags)
-	    && !test_bit(R5_LOCKED, &sh->dev[s.failed_num].flags)
-	    && test_bit(R5_UPTODATE, &sh->dev[s.failed_num].flags)
+	    test_bit(R5_ReadError, &sh->dev[s.failed_num[0]].flags)
+	    && !test_bit(R5_LOCKED, &sh->dev[s.failed_num[0]].flags)
+	    && test_bit(R5_UPTODATE, &sh->dev[s.failed_num[0]].flags)
 		) {
-		dev = &sh->dev[s.failed_num];
+		dev = &sh->dev[s.failed_num[0]];
 		if (!test_bit(R5_ReWrite, &dev->flags)) {
 			set_bit(R5_Wantwrite, &dev->flags);
 			set_bit(R5_ReWrite, &dev->flags);
@@ -3292,7 +3292,6 @@ static void handle_stripe6(struct stripe_head *sh)
 	struct bio *return_bi = NULL;
 	int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx;
 	struct stripe_head_state s;
-	struct r6_state r6s;
 	struct r5dev *dev, *pdev, *qdev;
 	mdk_rdev_t *blocked_rdev = NULL;
 	int dec_preread_active = 0;
@@ -3370,7 +3369,7 @@ static void handle_stripe6(struct stripe_head *sh)
 			clear_bit(R5_Insync, &dev->flags);
 		if (!test_bit(R5_Insync, &dev->flags)) {
 			if (s.failed < 2)
-				r6s.failed_num[s.failed] = i;
+				s.failed_num[s.failed] = i;
 			s.failed++;
 		}
 	}
@@ -3396,7 +3395,7 @@ static void handle_stripe6(struct stripe_head *sh)
 	pr_debug("locked=%d uptodate=%d to_read=%d"
 	       " to_write=%d failed=%d failed_num=%d,%d\n",
 	       s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
-	       r6s.failed_num[0], r6s.failed_num[1]);
+	       s.failed_num[0], s.failed_num[1]);
 	/* check if the array has lost >2 devices and, if so, some requests
 	 * might need to be failed
 	 */
@@ -3413,17 +3412,17 @@ static void handle_stripe6(struct stripe_head *sh)
 	 * are safe, or on a failed drive
 	 */
 	pdev = &sh->dev[pd_idx];
-	r6s.p_failed = (s.failed >= 1 && r6s.failed_num[0] == pd_idx)
-		|| (s.failed >= 2 && r6s.failed_num[1] == pd_idx);
+	s.p_failed = (s.failed >= 1 && s.failed_num[0] == pd_idx)
+		|| (s.failed >= 2 && s.failed_num[1] == pd_idx);
 	qdev = &sh->dev[qd_idx];
-	r6s.q_failed = (s.failed >= 1 && r6s.failed_num[0] == qd_idx)
-		|| (s.failed >= 2 && r6s.failed_num[1] == qd_idx);
+	s.q_failed = (s.failed >= 1 && s.failed_num[0] == qd_idx)
+		|| (s.failed >= 2 && s.failed_num[1] == qd_idx);
 
-	if ( s.written &&
-	     ( r6s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
+	if (s.written &&
+	    (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
 			     && !test_bit(R5_LOCKED, &pdev->flags)
 			     && test_bit(R5_UPTODATE, &pdev->flags)))) &&
-	     ( r6s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
+	    (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
 			     && !test_bit(R5_LOCKED, &qdev->flags)
 			     && test_bit(R5_UPTODATE, &qdev->flags)))))
 		handle_stripe_clean_event(conf, sh, disks, &return_bi);
@@ -3434,7 +3433,7 @@ static void handle_stripe6(struct stripe_head *sh)
 	 */
 	if (s.to_read || s.non_overwrite || (s.to_write && s.failed) ||
 	    (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding)
-		handle_stripe_fill6(sh, &s, &r6s, disks);
+		handle_stripe_fill6(sh, &s, disks);
 
 	/* Now we check to see if any write operations have recently
 	 * completed
@@ -3472,7 +3471,7 @@ static void handle_stripe6(struct stripe_head *sh)
 	 *    block.
 	 */
 	if (s.to_write && !sh->reconstruct_state && !sh->check_state)
-		handle_stripe_dirtying6(conf, sh, &s, &r6s, disks);
+		handle_stripe_dirtying6(conf, sh, &s, disks);
 
 	/* maybe we need to check and possibly fix the parity for this stripe
 	 * Any reads will already have been scheduled, so we just see if enough
@@ -3483,7 +3482,7 @@ static void handle_stripe6(struct stripe_head *sh)
 	    (s.syncing && s.locked == 0 &&
 	     !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
 	     !test_bit(STRIPE_INSYNC, &sh->state)))
-		handle_parity_checks6(conf, sh, &s, &r6s, disks);
+		handle_parity_checks6(conf, sh, &s, disks);
 
 	if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
 		md_done_sync(conf->mddev, STRIPE_SECTORS,1);
@@ -3495,7 +3494,7 @@ static void handle_stripe6(struct stripe_head *sh)
 	 */
 	if (s.failed <= 2 && !conf->mddev->ro)
 		for (i = 0; i < s.failed; i++) {
-			dev = &sh->dev[r6s.failed_num[i]];
+			dev = &sh->dev[s.failed_num[i]];
 			if (test_bit(R5_ReadError, &dev->flags)
 			    && !test_bit(R5_LOCKED, &dev->flags)
 			    && test_bit(R5_UPTODATE, &dev->flags)
@@ -3557,7 +3556,7 @@ static void handle_stripe6(struct stripe_head *sh)
 
 	if (s.expanding && s.locked == 0 &&
 	    !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
-		handle_stripe_expansion(conf, sh, &r6s);
+		handle_stripe_expansion(conf, sh, &s);
 
  unlock:
 

drivers/md/raid5.h

@@ -242,13 +242,9 @@ struct stripe_head_state {
 	int syncing, expanding, expanded;
 	int locked, uptodate, to_read, to_write, failed, written;
 	int to_fill, compute, req_compute, non_overwrite;
-	int failed_num;
+	int failed_num[2];
 	unsigned long ops_request;
-};
-
-/* r6_state - extra state data only relevant to r6 */
-struct r6_state {
-	int p_failed, q_failed, failed_num[2];
+	int p_failed, q_failed;
 };
 
 /* Flags */