debug/sink: add xlator to aid in resource leak debugging

This new xlator does not allocate any resources on init(). This makes it
a good option to use for debugging xlator releated resources leaks on
fini().

By putting the sink xlator as single xlator in a .vol file, and loading
it through gfapi, we can investigate the resource leaks that are
happening through gfapi (and the Gluster core). By extending the .vol
file with additional xlators, it is possible to analyze resource leaks
of single xlators.

Change-Id: Idb5faa861b623dd5b2a988b181e669b0d52c2a0e
BUG: 1425623
Fixes: #176
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: https://review.gluster.org/16806
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>

4 files changed, 96 insertions, 1 deletions

diff --git a/xlators/debug/Makefile.am b/xlators/debug/Makefile.am
index b655554efec..6e476152ddc 100644
--- a/xlators/debug/Makefile.am
+++ b/xlators/debug/Makefile.am
@@ -1,3 +1,3 @@
-SUBDIRS = trace error-gen io-stats
+SUBDIRS = error-gen io-stats sink trace
 
 CLEANFILES = 
diff --git a/xlators/debug/sink/Makefile.am b/xlators/debug/sink/Makefile.am
new file mode 100644
index 00000000000..f2689244371
--- /dev/null
+++ b/xlators/debug/sink/Makefile.am
@@ -0,0 +1,2 @@
+SUBDIRS = src
+
diff --git a/xlators/debug/sink/src/Makefile.am b/xlators/debug/sink/src/Makefile.am
new file mode 100644
index 00000000000..f952c2ce6bc
--- /dev/null
+++ b/xlators/debug/sink/src/Makefile.am
@@ -0,0 +1,14 @@
+xlator_LTLIBRARIES = sink.la
+xlatordir = $(libdir)/glusterfs/$(PACKAGE_VERSION)/xlator/debug
+
+AM_CPPFLAGS = $(GF_CPPFLAGS) -I$(top_srcdir)/libglusterfs/src \
+        -I$(top_builddir)/rpc/xdr/src
+AM_CFLAGS = -Wall $(GF_CFLAGS)
+
+sink_la_LDFLAGS = -module $(GF_XLATOR_DEFAULT_LDFLAGS)
+
+sink_la_SOURCES = sink.c
+sink_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la
+
+CLEANFILES =
+
diff --git a/xlators/debug/sink/src/sink.c b/xlators/debug/sink/src/sink.c
new file mode 100644
index 00000000000..dfd5685a969
--- /dev/null
+++ b/xlators/debug/sink/src/sink.c
@@ -0,0 +1,79 @@
+/*
+   Copyright (c) 2017 Red Hat, Inc. <http://www.redhat.com>
+   This file is part of GlusterFS.
+
+   This file is licensed to you under your choice of the GNU Lesser
+   General Public License, version 3 or any later version (LGPLv3 or
+   later), or the GNU General Public License, version 2 (GPLv2), in all
+   cases as published by the Free Software Foundation.
+*/
+
+#include "xlator.h"
+#include "defaults.h"
+
+int32_t
+init (xlator_t *this)
+{
+        return 0;
+}
+
+void
+fini (xlator_t *this)
+{
+        return;
+}
+
+/*
+ * notify - when parent sends PARENT_UP, send CHILD_UP event from here
+ */
+int32_t
+notify (xlator_t *this, int32_t event, void *data, ...)
+{
+        switch (event) {
+        case GF_EVENT_PARENT_UP:
+                /* Tell the parent that this xlator is up */
+                default_notify (this, GF_EVENT_CHILD_UP, data);
+                break;
+        case GF_EVENT_PARENT_DOWN:
+                /* Tell the parent that this xlator is down */
+                default_notify (this, GF_EVENT_CHILD_DOWN, data);
+                break;
+        default:
+                break;
+        }
+
+        return 0;
+}
+
+/*
+ * A lookup on "/" is done while mounting or glfs_init() is performed. This
+ * needs to return a valid directory for the root of the mountpoint.
+ *
+ * In case this xlator is used for more advanced debugging, it will need to be
+ * extended to support different LOOKUPs too.
+ */
+static int32_t
+sink_lookup (call_frame_t *frame, xlator_t *this, loc_t *loc, dict_t *xdata)
+{
+        struct iatt stbuf = { 0, };
+        struct iatt postparent = { 0, };
+
+        /* the root of the volume always need to be a directory */
+        stbuf.ia_type = IA_IFDIR;
+
+        STACK_UNWIND_STRICT (lookup, frame, 0, 0, loc ? loc->inode : NULL,
+                             &stbuf, xdata, &postparent);
+
+        return 0;
+}
+
+struct xlator_fops fops = {
+        .lookup = sink_lookup,
+};
+
+struct xlator_cbks cbks = {
+};
+
+struct volume_options options[] = {
+        { .key  = {NULL} },
+};