cluster/ec: fix bug in update_good

Problem:
Bricks that didn't participate in the fops are considered to be good. This is happening two fold.
Examples:
Case-1:
1) 2+1 volume. 'd1' directory on Brick-0 is bad.
2) readdir takes locks and lock->good_mask is '7'
3) readdir does xattrop and fop->mask is '6'.
4) because fop->expected is '1' lock->good_mask remains '7'

Case-2:
1) when all the bricks are up, it does lock + xattrop before op and figures out
   all the bricks are good.
2) By the time second operation starts brick-0 is down. Now lock->good_mask
   will always have the '0' bit set as long as the operations are happening on it.
   because: "lock->good_mask &= ~fop->mask | fop->remaining" fop->mask doesn't
   have '0' th bit.
3) When it comes time to perform the final xattrop in update_size_version
   brick-0 comes online because of which it gives the same version to brick-0
   as well thinking it has participated in all the transactions till then, even
   when it didn't participate in the transactions.

Fix:
Case-1's fix: Update lock->good_mask in ec_prepare_update_cbk with latest
good/bad bricks
Case-2's fix: Consider non-participating brick as bad.

Change-Id: Ic01a733f8180131ded6a3cc784fcb1960758cf23
BUG: 1276989
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/12561
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Xavier Hernandez <xhernandez@datalab.es>

1 files changed, 7 insertions, 5 deletions

diff --git a/xlators/cluster/ec/src/ec-common.c b/xlators/cluster/ec/src/ec-common.c
index a7d6da4038f..da67dbc0f95 100644
--- a/xlators/cluster/ec/src/ec-common.c
+++ b/xlators/cluster/ec/src/ec-common.c
@@ -154,11 +154,12 @@ void ec_lock_update_good(ec_lock_t *lock, ec_fop_data_t *fop)
         return;
     }
 
-    /* When updating the good mask of the lock, we only take into
-     * consideration those bits corresponding to the bricks where
-     * the fop has been executed. */
-    lock->good_mask &= ~fop->mask | fop->remaining;
-    lock->good_mask |= fop->good;
+    /* When updating the good mask of the lock, we only take into consideration
+     * those bits corresponding to the bricks where the fop has been executed.
+     * Bad bricks are removed from good_mask, but once marked as bad it's never
+     * set to good until the lock is released and reacquired */
+
+    lock->good_mask &= fop->good | fop->remaining;
 }
 
 void __ec_fop_set_error(ec_fop_data_t * fop, int32_t error)
@@ -981,6 +982,7 @@ unlock:
         /* We don't allow the main fop to be executed on bricks that have not
          * succeeded the initial xattrop. */
         parent->mask &= fop->good;
+        ec_lock_update_good (lock, fop);
 
         /*As of now only data healing marks bricks as healing*/
         lock->healing |= fop->healing;