performance/md-cache: Fix a crash when statfs caching is enabled

mem_put() in STACK_UNWIND_STRICT causes a crash if frame->local is not null
as md-cache obtains local from CALLOC.

Changed two occurrences of STACK_UNWIND_STRICT to MDC_STACK_UNWIND as
the latter macro does not rely on STACK_UNWIND_STRICT for cleaning up
frame->local.

fixes: bz#1632503
Change-Id: I1b3edcb9372a164ef73119e99a49e747765d7166
Signed-off-by: Vijay Bellur <vbellur@redhat.com>

2 files changed, 26 insertions, 2 deletions

diff --git a/tests/bugs/md-cache/bug-1632503.t b/tests/bugs/md-cache/bug-1632503.t
new file mode 100755
index 00000000000..aeb57f65639
--- /dev/null
+++ b/tests/bugs/md-cache/bug-1632503.t
@@ -0,0 +1,24 @@
+#!/bin/bash
+
+. $(dirname $0)/../../include.rc
+. $(dirname $0)/../../volume.rc
+
+cleanup;
+TESTS_EXPECTED_IN_LOOP=5
+
+TEST glusterd;
+
+TEST $CLI volume create $V0 $H0:$B0/${V0}{1,2,3};
+
+TEST $CLI volume start $V0
+
+TEST $CLI volume set $V0 performance.md-cache-timeout 600
+TEST $CLI volume set $V0 performance.md-cache-statfs on
+
+TEST glusterfs --volfile-id=/$V0 --volfile-server=$H0 $M0
+
+for i in $(seq 1 5); do
+    TEST_IN_LOOP df $M0;
+done
+
+cleanup;
diff --git a/xlators/performance/md-cache/src/md-cache.c b/xlators/performance/md-cache/src/md-cache.c
index 1f19d5b2c79..ff5c8c2f914 100644
--- a/xlators/performance/md-cache/src/md-cache.c
+++ b/xlators/performance/md-cache/src/md-cache.c
@@ -1174,7 +1174,7 @@ uncached:
     return 0;
 
 out:
-    STACK_UNWIND_STRICT(statfs, frame, op_ret, op_errno, buf, xdata);
+    MDC_STACK_UNWIND(statfs, frame, op_ret, op_errno, buf, xdata);
     return 0;
 }
 
@@ -2834,7 +2834,7 @@ mdc_readdirp(call_frame_t *frame, xlator_t *this, fd_t *fd, size_t size,
         dict_unref(xattr_alloc);
     return 0;
 out:
-    STACK_UNWIND_STRICT(readdirp, frame, -1, ENOMEM, NULL, NULL);
+    MDC_STACK_UNWIND(readdirp, frame, -1, ENOMEM, NULL, NULL);
     return 0;
 }