md/raid5: unite handle_stripe_dirtying5 and handle_stripe_dirtying6

RAID6 is only allowed to choose 'reconstruct-write' while RAID5 is
also allow 'read-modify-write'
Apart from this difference, handle_stripe_dirtying[56] are nearly
identical.  So resolve these differences and create just one function.

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

1 files changed, 21 insertions, 56 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index a63a679105ca..a3018970d6a3 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2468,11 +2468,19 @@ static void handle_stripe_clean_event(raid5_conf_t *conf,
                         md_wakeup_thread(conf->mddev->thread);
 }
 
-static void handle_stripe_dirtying5(raid5_conf_t *conf,
-                struct stripe_head *sh, struct stripe_head_state *s, int disks)
+static void handle_stripe_dirtying(raid5_conf_t *conf,
+                                   struct stripe_head *sh,
+                                   struct stripe_head_state *s,
+                                   int disks)
 {
         int rmw = 0, rcw = 0, i;
-        for (i = disks; i--; ) {
+        if (conf->max_degraded == 2) {
+                /* RAID6 requires 'rcw' in current implementation
+                 * Calculate the real rcw later - for now fake it
+                 * look like rcw is cheaper
+                 */
+                rcw = 1; rmw = 2;
+        } else for (i = disks; i--; ) {
                 /* would I have to read this buffer for read_modify_write */
                 struct r5dev *dev = &sh->dev[i];
                 if ((dev->towrite || i == sh->pd_idx) &&
@@ -2519,16 +2527,19 @@ static void handle_stripe_dirtying5(raid5_conf_t *conf,
                                 }
                         }
                 }
-        if (rcw <= rmw && rcw > 0)
+        if (rcw <= rmw && rcw > 0) {
                 /* want reconstruct write, but need to get some data */
+                rcw = 0;
                 for (i = disks; i--; ) {
                         struct r5dev *dev = &sh->dev[i];
                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
-                            i != sh->pd_idx &&
+                            i != sh->pd_idx && i != sh->qd_idx &&
                             !test_bit(R5_LOCKED, &dev->flags) &&
                             !(test_bit(R5_UPTODATE, &dev->flags) ||
-                            test_bit(R5_Wantcompute, &dev->flags)) &&
-                            test_bit(R5_Insync, &dev->flags)) {
+                              test_bit(R5_Wantcompute, &dev->flags))) {
+                                rcw++;
+                                if (!test_bit(R5_Insync, &dev->flags))
+                                        continue; /* it's a failed drive */
                                 if (
                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
                                         pr_debug("Read_old block "
@@ -2542,6 +2553,7 @@ static void handle_stripe_dirtying5(raid5_conf_t *conf,
                                 }
                         }
                 }
+        }
         /* now if nothing is locked, and if we have enough data,
          * we can start a write request
          */
@@ -2558,53 +2570,6 @@ static void handle_stripe_dirtying5(raid5_conf_t *conf,
                 schedule_reconstruction(sh, s, rcw == 0, 0);
 }
 
-static void handle_stripe_dirtying6(raid5_conf_t *conf,
-                struct stripe_head *sh, struct stripe_head_state *s,
-                int disks)
-{
-        int rcw = 0, pd_idx = sh->pd_idx, i;
-        int qd_idx = sh->qd_idx;
-
-        set_bit(STRIPE_HANDLE, &sh->state);
-        for (i = disks; i--; ) {
-                struct r5dev *dev = &sh->dev[i];
-                /* check if we haven't enough data */
-                if (!test_bit(R5_OVERWRITE, &dev->flags) &&
-                    i != pd_idx && i != qd_idx &&
-                    !test_bit(R5_LOCKED, &dev->flags) &&
-                    !(test_bit(R5_UPTODATE, &dev->flags) ||
-                      test_bit(R5_Wantcompute, &dev->flags))) {
-                        rcw++;
-                        if (!test_bit(R5_Insync, &dev->flags))
-                                continue; /* it's a failed drive */
-
-                        if (
-                          test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
-                                pr_debug("Read_old stripe %llu "
-                                        "block %d for Reconstruct\n",
-                                     (unsigned long long)sh->sector, i);
-                                set_bit(R5_LOCKED, &dev->flags);
-                                set_bit(R5_Wantread, &dev->flags);
-                                s->locked++;
-                        } else {
-                                pr_debug("Request delayed stripe %llu "
-                                        "block %d for Reconstruct\n",
-                                     (unsigned long long)sh->sector, i);
-                                set_bit(STRIPE_DELAYED, &sh->state);
-                                set_bit(STRIPE_HANDLE, &sh->state);
-                        }
-                }
-        }
-        /* now if nothing is locked, and if we have enough data, we can start a
-         * write request
-         */
-        if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
-            s->locked == 0 && rcw == 0 &&
-            !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
-                schedule_reconstruction(sh, s, 1, 0);
-        }
-}
-
 static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
                                 struct stripe_head_state *s, int disks)
 {
@@ -3099,7 +3064,7 @@ static int handle_stripe5(struct stripe_head *sh, struct stripe_head_state *s)
          *    block.
          */
         if (s->to_write && !sh->reconstruct_state && !sh->check_state)
-                handle_stripe_dirtying5(conf, sh, s, disks);
+                handle_stripe_dirtying(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
@@ -3288,7 +3253,7 @@ static int handle_stripe6(struct stripe_head *sh, struct stripe_head_state *s)
          *    block.
          */
         if (s->to_write && !sh->reconstruct_state && !sh->check_state)
-                handle_stripe_dirtying6(conf, sh, s, disks);
+                handle_stripe_dirtying(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