[PATCH V2 1/1] mdadm/Grow: Update new level when starting reshape

[Xiao Ni <xni@redhat.com>]

Reshape needs to specify a backup file when it can't update data offset
of member disks. For this situation, first, it starts reshape and then
it kicks off mdadm-grow-continue service which does backup job and
monitors the reshape process. The service is a new process, so it needs
to read superblock from member disks to get information.

But in the first step, it doesn't update new level in superblock. So
it can't change level after reshape finishes, because the new level is
not right. So records the new level in the first step.

Signed-off-by: Xiao Ni <xni@redhat.com>
---
v2: format change, add get_linux_version
 Grow.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Grow.c b/Grow.c
index 5810b128aa99..533f301468af 100644
--- a/Grow.c
+++ b/Grow.c
@@ -2941,15 +2941,24 @@ static int impose_reshape(struct mdinfo *sra,
 		 * persists from some earlier problem.
 		 */
 		int err = 0;
+
 		if (sysfs_set_num(sra, NULL, "chunk_size", info->new_chunk) < 0)
 			err = errno;
+
 		if (!err && sysfs_set_num(sra, NULL, "layout",
 					  reshape->after.layout) < 0)
 			err = errno;
+
+		/* new_level is introduced in kernel 6.12 */
+		if (!err && get_linux_version() >= 6012000 &&
+				sysfs_set_num(sra, NULL, "new_level", info->new_level) < 0)
+			err = errno;
+
 		if (!err && subarray_set_num(container, sra, "raid_disks",
 					     reshape->after.data_disks +
 					     reshape->parity) < 0)
 			err = errno;
+
 		if (err) {
 			pr_err("Cannot set device shape for %s\n", devname);
 
-- 
2.32.0 (Apple Git-132)