gfapi/handleops: Introducing glfs_xreaddirplus_r() fop for handleops

Its known that readdirplus operation fetches stat as well for each of the
dirents. But often applications may need extra information, like for eg.,
NFS-Ganesha which operates on handles needs handles for each of those
dirents returned. So this would require extra calls to the backend, in this
case LOOKUP (which is very expensive operation) resulting in very low
readdir performance.

To address that introducing this new API using which applications can
make request for any extra information to be returned as part of
readdirplus response.

Currently this new api returns stat and handles as demanded by application.
The synopsis of the API is noted in glfs.h.

@todo:
* Enhance test script using this new API

Below were the perf results on single brick volume with and without
these changes -

Dataset used -
10*100 directories and each directory containing 100 empty files.

I used NFS-Ganesha application to test these changes -
>for i in {1..5}; do systemctl restart nfs-ganesha; sleep 10; mount -t nfs -o vers=4 localhost:/brick_vol /mnt; cd /mnt; echo "ITERATION$i"; date; find . > tmp-nfs.log; date; cd /; umount /mnt; sleep 2; done;

Without these changes -
ITERATION1
Mon Mar 20 17:22:26 IST 2017
Mon Mar 20 17:23:18 IST 2017
ITERATION2
Mon Mar 20 17:23:39 IST 2017
Mon Mar 20 17:24:28 IST 2017
ITERATION3
Mon Mar 20 17:24:49 IST 2017
Mon Mar 20 17:25:36 IST 2017
ITERATION4
Mon Mar 20 17:30:57 IST 2017
Mon Mar 20 17:31:37 IST 2017
ITERATION5
Mon Mar 20 17:31:57 IST 2017
Mon Mar 20 17:32:40 IST 2017
[root@dhcp35-197 /]#

On an average ~46.2 sec

With these changes applied -
ITERATION1
Mon Mar 20 17:35:03 IST 2017
Mon Mar 20 17:35:15 IST 2017
ITERATION2
Mon Mar 20 17:35:36 IST 2017
Mon Mar 20 17:35:46 IST 2017
ITERATION3
Mon Mar 20 17:36:06 IST 2017
Mon Mar 20 17:36:17 IST 2017
ITERATION4
Mon Mar 20 17:41:38 IST 2017
Mon Mar 20 17:41:49 IST 2017
ITERATION5
Mon Mar 20 17:42:10 IST 2017
Mon Mar 20 17:42:20 IST 2017

On an average ~10.8 sec

This is backport of below upstream patch -
        https://review.gluster.org/15663

>Updates #174
>BUG: 1442950
>Change-Id: I0f74f74dc62085ca4c4a23c38e3edc84bd850876
>Signed-off-by: Soumya Koduri <skoduri@redhat.com>
>Reviewed-on: https://review.gluster.org/15663
>Smoke: Gluster Build System <jenkins@build.gluster.org>
>NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
>Reviewed-by: Niels de Vos <ndevos@redhat.com>
>CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

BUG: 1447571
Change-Id: I0f74f74dc62085ca4c4a23c38e3edc84bd850876
Signed-off-by: Soumya Koduri <skoduri@redhat.com>
Reviewed-on: https://review.gluster.org/17164
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Niels de Vos <ndevos@redhat.com>

2 files changed, 134 insertions, 0 deletions

diff --git a/tests/basic/gfapi/glfs_xreaddirplus_r.c b/tests/basic/gfapi/glfs_xreaddirplus_r.c
new file mode 100644
index 00000000000..eed80686d70
--- /dev/null
+++ b/tests/basic/gfapi/glfs_xreaddirplus_r.c
@@ -0,0 +1,107 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <glusterfs/api/glfs.h>
+#include <glusterfs/api/glfs-handles.h>
+
+#define VALIDATE_AND_GOTO_LABEL_ON_ERROR(func, ret, label) do { \
+        if (ret < 0) {            \
+                fprintf (stderr, "%s : returned error %d (%s)\n", \
+                         func, ret, strerror (errno)); \
+                goto label; \
+        } \
+        } while (0)
+
+#define MAX_FILES_CREATE 10
+#define MAXPATHNAME      512
+
+int
+main (int argc, char *argv[])
+{
+        int                     ret = -1;
+        glfs_t                 *fs = NULL;
+        char                   *volname = NULL;
+        char                   *logfile = NULL;
+        char                   *hostname = NULL;
+        char                   *my_file = "file_";
+        char                    my_file_name[MAXPATHNAME];
+        struct dirent           de;
+        struct dirent          *pde = NULL;
+        struct glfs_xreaddirp_stat   *xstat = NULL;
+        uint32_t                rflags = (GFAPI_XREADDIRP_STAT |
+                                          GFAPI_XREADDIRP_HANDLE);
+        uint32_t                flags = O_RDWR|O_SYNC;
+        struct glfs_fd         *fd = NULL;
+        int                     i = 0;
+
+        if (argc != 4) {
+                fprintf (stderr, "Invalid argument\n");
+                return 1;
+        }
+
+        hostname = argv[1];
+        volname = argv[2];
+        logfile = argv[3];
+
+        fs = glfs_new (volname);
+        if (!fs)
+                VALIDATE_AND_GOTO_LABEL_ON_ERROR ("glfs_new", ret, out);
+
+        ret = glfs_set_volfile_server (fs, "tcp", hostname, 24007);
+        VALIDATE_AND_GOTO_LABEL_ON_ERROR ("glfs_set_volfile_server", ret, out);
+
+        ret = glfs_set_logging (fs, logfile, 7);
+        VALIDATE_AND_GOTO_LABEL_ON_ERROR ("glfs_set_logging", ret, out);
+
+        ret = glfs_init (fs);
+        VALIDATE_AND_GOTO_LABEL_ON_ERROR ("glfs_init", ret, out);
+
+        for (i = 0; i < MAX_FILES_CREATE; i++) {
+                sprintf (my_file_name, "%s%d", my_file, i);
+
+                fd = glfs_creat(fs, my_file_name, flags, 0644);
+                if (fd == NULL) {
+                        ret = -1;
+                        VALIDATE_AND_GOTO_LABEL_ON_ERROR ("glfs_creat", ret,
+                                                          out);
+                }
+
+
+                glfs_close (fd);
+        }
+
+        /* XXX: measure performance and memory usage of this readdirp call */
+        fd = glfs_opendir (fs, "/");
+
+        ret = glfs_xreaddirplus_r(fd, rflags, &xstat, &de, &pde);
+        while (ret > 0 && pde != NULL) {
+                fprintf (stderr, "%s: %lu\n", de.d_name, glfs_telldir (fd));
+
+                if (xstat)
+                        glfs_free(xstat);
+
+                ret = glfs_xreaddirplus_r(fd, rflags, &xstat, &de, &pde);
+
+                /* XXX: Use other APIs to fetch stat and handles */
+        }
+
+        if (xstat)
+                glfs_free(xstat);
+
+        VALIDATE_AND_GOTO_LABEL_ON_ERROR ("glfs_xreaddirp_r", ret, out);
+
+out:
+        if (fd != NULL)
+                glfs_close(fd);
+
+        if (fs) {
+                ret = glfs_fini(fs);
+                if (ret)
+                        fprintf (stderr, "glfs_fini(fs) returned %d\n", ret);
+        }
+
+        return ret;
+}
+
+
diff --git a/tests/basic/gfapi/glfs_xreaddirplus_r.t b/tests/basic/gfapi/glfs_xreaddirplus_r.t
new file mode 100755
index 00000000000..fa882f1849f
--- /dev/null
+++ b/tests/basic/gfapi/glfs_xreaddirplus_r.t
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+. $(dirname $0)/../../include.rc
+. $(dirname $0)/../../volume.rc
+
+cleanup;
+
+TEST glusterd
+
+TEST $CLI volume create $V0 $H0:$B0/brick1;
+EXPECT 'Created' volinfo_field $V0 'Status';
+
+TEST $CLI volume start $V0;
+EXPECT 'Started' volinfo_field $V0 'Status';
+
+logdir=`gluster --print-logdir`
+
+TEST build_tester $(dirname $0)/glfs_xreaddirplus_r.c -lgfapi
+
+TEST $(dirname $0)/glfs_xreaddirplus_r $H0 $V0  $logdir/glfs_xreaddirplus_r.log
+
+cleanup_tester $(dirname $0)/glfs_xreaddirplus_r
+
+TEST $CLI volume stop $V0
+TEST $CLI volume delete $V0
+
+cleanup;