This is unlikely to be wanted, but we may as well provide it
for completeness.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
drivers/md/raid5.c | 13 +++++++++++++
1 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index bb28fd6..020143d 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5788,6 +5788,18 @@ static void *raid5_takeover(mddev_t *mddev)
return ERR_PTR(-EINVAL);
}
+static void *raid4_takeover(mddev_t *mddev)
+{
+ /* raid4 can take over raid5 if layout is right.
+ */
+ if (mddev->level == 5 &&
+ mddev->layout == ALGORITHM_PARITY_N) {
+ mddev->new_layout = 0;
+ mddev->new_level = 4;
+ return setup_conf(mddev);
+ }
+ return ERR_PTR(-EINVAL);
+}
static struct mdk_personality raid5_personality;
@@ -5903,6 +5915,7 @@ static struct mdk_personality raid4_personality =
.start_reshape = raid5_start_reshape,
.finish_reshape = raid5_finish_reshape,
.quiesce = raid5_quiesce,
+ .takeover = raid4_takeover,
};
static int __init raid5_init(void)
--
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