DDF: explain why spare_refs are ignored.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/super-ddf.c b/super-ddf.c
index a5245d3b2c58c94879b2eeb0591cb0c247a6cb98..fda416012f08430b4bff2fabc880f67733e04a47 100644 (file)
--- a/super-ddf.c
+++ b/super-ddf.c
@@ -343,7 +343,10 @@ struct vd_config {
                                 * for concat I hope) */
        be64    array_blocks;   /* blocks in array */
        __u8    pad1[8];
-       be32    spare_refs[8];
+       be32    spare_refs[8];  /* This is used to detect missing spares.
+                                * As we don't have an interface for that
+                                * the values are ignored.
+                                */
        __u8    cache_pol[8];
        __u8    bg_rate;
        __u8    pad2[3];