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-rw-r--r--include/linux/crush/crush.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/crush/crush.h b/include/linux/crush/crush.h
index acaa5615d634..4fad5f8ee01d 100644
--- a/include/linux/crush/crush.h
+++ b/include/linux/crush/crush.h
@@ -51,6 +51,7 @@ enum {
CRUSH_RULE_SET_CHOOSELEAF_TRIES = 9, /* override chooseleaf_descend_once */
CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES = 10,
CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES = 11,
+ CRUSH_RULE_SET_CHOOSELEAF_VARY_R = 12
};
/*
@@ -173,6 +174,12 @@ struct crush_map {
* apply to a collision: in that case we will retry as we used
* to. */
__u32 chooseleaf_descend_once;
+
+ /* if non-zero, feed r into chooseleaf, bit-shifted right by (r-1)
+ * bits. a value of 1 is best for new clusters. for legacy clusters
+ * that want to limit reshuffling, a value of 3 or 4 will make the
+ * mappings line up a bit better with previous mappings. */
+ __u8 chooseleaf_vary_r;
};