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>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index a63a679..a301897 100644 (file)
--- 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