From 90dc8d7cee42eeacc3214fef8bb45cbffc4c8de5 Mon Sep 17 00:00:00 2001
From: N Balachandran <nbalacha@redhat.com>
Date: Mon, 19 Feb 2018 09:44:29 +0530
Subject: [PATCH 162/180] cluster/dht: Handle single dht child in dht_lookup

This patch limits itself to only handling the case
where no file (data or linkto) exists on the subvol.

Additional cases to be handled:
1. A linkto file was found on the only child subvol. This currently
calls dht_lookup_everywhere which eventually deletes it. It can be
deleted directly as it will not be pointing to a valid subvol.
2. Directory lookups - locking might be unnecessary in some cases.

upstream patch: https://review.gluster.org/19581

> Change-Id: I940ba34531f2aaee1d36fd9ca45ecfd46be662a4
> BUG: 1546620
> Signed-off-by: N Balachandran <nbalacha@redhat.com>

Change-Id: I1cc1b9866fa18fe825847585e6a9b8c92898951a
BUG: 1545570
Signed-off-by: N Balachandran <nbalacha@redhat.com>
Reviewed-on: https://code.engineering.redhat.com/gerrit/130976
Tested-by: RHGS Build Bot <nigelb@redhat.com>
Reviewed-by: Shyam Ranganathan <srangana@redhat.com>
---
 xlators/cluster/dht/src/dht-common.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/xlators/cluster/dht/src/dht-common.c b/xlators/cluster/dht/src/dht-common.c
index 1262732..5641330 100644
--- a/xlators/cluster/dht/src/dht-common.c
+++ b/xlators/cluster/dht/src/dht-common.c
@@ -2352,6 +2352,12 @@ dht_lookup_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         }
 
         if (ENTRY_MISSING (op_ret, op_errno)) {
+
+                if (1 == conf->subvolume_cnt) {
+                        /* No need to lookup again */
+                        goto out;
+                }
+
                 gf_msg_debug (this->name, 0,
                               "Entry %s missing on subvol %s",
                               loc->path, prev->name);
@@ -2581,6 +2587,8 @@ dht_lookup (call_frame_t *frame, xlator_t *this,
                 local->xattr_req = dict_new ();
         }
 
+        /* Nameless lookup */
+
         if (gf_uuid_is_null (loc->pargfid) && !gf_uuid_is_null (loc->gfid) &&
             !__is_root_gfid (loc->inode->gfid)) {
                 local->cached_subvol = NULL;
@@ -2598,6 +2606,9 @@ dht_lookup (call_frame_t *frame, xlator_t *this,
                 hashed_subvol = dht_subvol_get_hashed (this, loc);
         local->hashed_subvol = hashed_subvol;
 
+
+        /* The entry has been looked up before and has an inode_ctx set
+         */
         if (is_revalidate (loc)) {
                 layout = local->layout;
                 if (!layout) {
@@ -2638,6 +2649,7 @@ dht_lookup (call_frame_t *frame, xlator_t *this,
                                 "path %s", conf->xattr_name, loc->path);
                         goto err;
                 }
+
                 /* need it in case file is not found on cached file
                  * on revalidate path and we may encounter linkto files on
                  * with dht_lookup_everywhere*/
-- 
1.8.3.1