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From: Ilya Dryomov <idryomov@gmail.com>
Date: Mon, 24 Jul 2017 16:43:49 +0200
Subject: libceph: fallback for when there isn't a pool-specific choose_arg
Git-commit: e17e8969f5c59a10083af5e260bdad6026872203
Patch-mainline: v4.13-rc4
References: FATE#324714

There is now a fallback to a choose_arg index of -1 if there isn't
a pool-specific choose_arg set.  If you create a per-pool weight-set,
that works for that pool.  Otherwise we try the compat/default one.  If
that doesn't exist either, then we use the normal CRUSH weights.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sage Weil <sage@redhat.com>
Acked-by: Luis Henriques <lhenriques@suse.com>
---
 include/linux/crush/crush.h |  2 +-
 net/ceph/osdmap.c           | 12 +++++++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/include/linux/crush/crush.h b/include/linux/crush/crush.h
index 92e165d417a6..07eed95e10c7 100644
--- a/include/linux/crush/crush.h
+++ b/include/linux/crush/crush.h
@@ -193,7 +193,7 @@ struct crush_choose_arg {
 struct crush_choose_arg_map {
 #ifdef __KERNEL__
 	struct rb_node node;
-	u64 choose_args_index;
+	s64 choose_args_index;
 #endif
 	struct crush_choose_arg *args; /*!< replacement for each bucket
                                             in the crushmap */
diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index 64ae9f89773a..eb57a06373ca 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -2301,10 +2301,17 @@ static u32 raw_pg_to_pps(struct ceph_pg_pool_info *pi,
 	}
 }
 
+/*
+ * Magic value used for a "default" fallback choose_args, used if the
+ * crush_choose_arg_map passed to do_crush() does not exist.  If this
+ * also doesn't exist, fall back to canonical weights.
+ */
+#define CEPH_DEFAULT_CHOOSE_ARGS	-1
+
 static int do_crush(struct ceph_osdmap *map, int ruleno, int x,
 		    int *result, int result_max,
 		    const __u32 *weight, int weight_max,
-		    u64 choose_args_index)
+		    s64 choose_args_index)
 {
 	struct crush_choose_arg_map *arg_map;
 	int r;
@@ -2313,6 +2320,9 @@ static int do_crush(struct ceph_osdmap *map, int ruleno, int x,
 
 	arg_map = lookup_choose_arg_map(&map->crush->choose_args,
 					choose_args_index);
+	if (!arg_map)
+		arg_map = lookup_choose_arg_map(&map->crush->choose_args,
+						CEPH_DEFAULT_CHOOSE_ARGS);
 
 	mutex_lock(&map->crush_workspace_mutex);
 	r = crush_do_rule(map->crush, ruleno, x, result, result_max,