md/raid5: Make sure we clear R5_Discard when discard is finished.

commit 9e44476851e91c86c98eb92b9bc27fb801f89072
    MD: raid5 avoid unnecessary zero page for trim

change raid5 to clear R5_Discard when the complete request is
handled rather than when submitting the per-device discard request.
However it did not clear R5_Discard for the parity device.

This means that if the stripe_head was reused before it expired from
the cache, the setting would be wrong and a hang would result.

Also if the R5_Uptodate bit happens to be set, R5_Discard again
won't be cleared.  But R5_Uptodate really should be clear at this point.

So make sure R5_Discard is cleared in all cases, and clear
R5_Uptodate when a 'discard' completes.

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

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 0fb988556eea..a4502686e7a8 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2774,10 +2774,12 @@ static void handle_stripe_clean_event(struct r5conf *conf,
                         dev = &sh->dev[i];
                         if (!test_bit(R5_LOCKED, &dev->flags) &&
                             (test_bit(R5_UPTODATE, &dev->flags) ||
-                             test_and_clear_bit(R5_Discard, &dev->flags))) {
+                             test_bit(R5_Discard, &dev->flags))) {
                                 /* We can return any write requests */
                                 struct bio *wbi, *wbi2;
                                 pr_debug("Return write for disc %d\n", i);
+                                if (test_and_clear_bit(R5_Discard, &dev->flags))
+                                        clear_bit(R5_UPTODATE, &dev->flags);
                                 wbi = dev->written;
                                 dev->written = NULL;
                                 while (wbi && wbi->bi_sector <
@@ -2795,7 +2797,8 @@ static void handle_stripe_clean_event(struct r5conf *conf,
                                          !test_bit(STRIPE_DEGRADED, &sh->state),
                                                 0);
                         }
-                }
+                } else if (test_bit(R5_Discard, &sh->dev[i].flags))
+                        clear_bit(R5_Discard, &sh->dev[i].flags);
 
         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
                 if (atomic_dec_and_test(&conf->pending_full_writes))