From ea71f09cd6ea45a2d1525519843fc553f0e46bec Mon Sep 17 00:00:00 2001
From: Zhang Huan <zhanghuan@open-fs.com>
Date: Tue, 5 Sep 2017 11:36:25 +0800
Subject: [PATCH 104/128] cluster/dht: fix crash when deleting directories

In DHT, after locks on all subvolumes are acquired, it would perform the
following steps sequentially,
1. send remove dir on all other subvolumes except the hashed one in a loop;
2. wait for all pending rmdir to be done
3. remove dir on the hashed subvolume

The problem is that in step 1 there is a check to skip hashed subvolume
in the loop. If the last subvolume to check is actually the
hashed one, and step 3 is quickly done before the last and hashed
subvolume is checked, by accessing shared context data be destroyed in
step 3, would cause a crash.

Fix by saving shared data in a local variable to access later in the
loop.

> BUG: 1490642
> Signed-off-by: Zhang Huan <zhanghuan@open-fs.com>
(cherry picked from commit 206120126d455417a81a48ae473d49be337e9463)
Change-Id: I8db7cf7cb262d74efcb58eb00f02ea37df4be4e2
BUG: 1519076
Signed-off-by: N Balachandran <nbalacha@redhat.com>
Reviewed-on: https://code.engineering.redhat.com/gerrit/124755
Tested-by: RHGS Build Bot <nigelb@redhat.com>
Reviewed-by: Raghavendra Gowdappa <rgowdapp@redhat.com>
---
 xlators/cluster/dht/src/dht-common.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/xlators/cluster/dht/src/dht-common.c b/xlators/cluster/dht/src/dht-common.c
index c6944b2..f611278 100644
--- a/xlators/cluster/dht/src/dht-common.c
+++ b/xlators/cluster/dht/src/dht-common.c
@@ -8094,6 +8094,7 @@ dht_rmdir_lock_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         dht_local_t  *local = NULL;
         dht_conf_t   *conf  = NULL;
         int           i     = 0;
+        xlator_t     *hashed_subvol;
 
         VALIDATE_OR_GOTO (this->private, err);
 
@@ -8111,9 +8112,10 @@ dht_rmdir_lock_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
                 goto err;
         }
 
+        hashed_subvol = local->hashed_subvol;
         for (i = 0; i < conf->subvolume_cnt; i++) {
-                if (local->hashed_subvol &&
-                    (local->hashed_subvol == conf->subvolumes[i]))
+                if (hashed_subvol &&
+                    (hashed_subvol == conf->subvolumes[i]))
                         continue;
 
                 STACK_WIND_COOKIE (frame, dht_rmdir_cbk, conf->subvolumes[i],
-- 
1.8.3.1