md/raid5: fix handling of degraded stripes in batches.

There is no need for special handling of stripe-batches when the array
is degraded.

There may be if there is a failure in the batch, but STRIPE_DEGRADED
does not imply an error.

So don't set STRIPE_BATCH_ERR in ops_run_io just because the array is
degraded.
This actually causes a bug: the STRIPE_DEGRADED flag gets cleared in
check_break_stripe_batch_list() and so the bitmap bit gets cleared
when it shouldn't.

So in check_break_stripe_batch_list(), split the batch up completely -
again STRIPE_DEGRADED isn't meaningful.

Also don't set STRIPE_BATCH_ERR when there is a write error to a
replacement device.  This simply removes the replacement device and
requires no extra handling.

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

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 3873eaa..1ba97fd 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1078,9 +1078,6 @@ again:
                        pr_debug("skip op %ld on disc %d for sector %llu\n",
                                bi->bi_rw, i, (unsigned long long)sh->sector);
                        clear_bit(R5_LOCKED, &sh->dev[i].flags);
-                       if (sh->batch_head)
-                               set_bit(STRIPE_BATCH_ERR,
-                                       &sh->batch_head->state);
                        set_bit(STRIPE_HANDLE, &sh->state);
                }
 
@@ -2448,7 +2445,7 @@ static void raid5_end_write_request(struct bio *bi, int error)
        }
        rdev_dec_pending(rdev, conf->mddev);
 
-       if (sh->batch_head && !uptodate)
+       if (sh->batch_head && !uptodate && !replacement)
                set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
 
        if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
@@ -4214,15 +4211,9 @@ static void check_break_stripe_batch_list(struct stripe_head *sh)
                return;
 
        head_sh = sh;
-       do {
-               sh = list_first_entry(&sh->batch_list,
-                                     struct stripe_head, batch_list);
-               BUG_ON(sh == head_sh);
-       } while (!test_bit(STRIPE_DEGRADED, &sh->state));
 
-       while (sh != head_sh) {
-               next = list_first_entry(&sh->batch_list,
-                                       struct stripe_head, batch_list);
+       list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
+
                list_del_init(&sh->batch_list);
 
                set_mask_bits(&sh->state, ~STRIPE_EXPAND_SYNC_FLAG,
@@ -4242,8 +4233,6 @@ static void check_break_stripe_batch_list(struct stripe_head *sh)
 
                set_bit(STRIPE_HANDLE, &sh->state);
                release_stripe(sh);
-
-               sh = next;
        }
 }