recreate journal in mdadm

This patch tries recreates missing/faulty journal in mdadm.

Example:

./mdadm --fail /dev/md1 /dev/sdb2
mdadm: set /dev/sdb2 faulty in /dev/md1

./mdadm --stop /dev/md1
mdadm: stopped /dev/md1

./mdadm -A --scan --force
mdadm: Journal is missing or stale, starting array read only.
mdadm: /dev/md/1 has been started with 15 drives.

./mdadm --add-journal /dev/md1 /dev/sdb2
mdadm: added /dev/sdb2

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/mdadm.c b/mdadm.c
index f56a8cf8..feec3b70 100644
--- a/mdadm.c
+++ b/mdadm.c
@@ -190,6 +190,7 @@ int main(int argc, char *argv[])
 		case 'a':
 		case Add:
 		case AddSpare:
+		case AddJournal:
 		case 'r':
 		case Remove:
 		case Replace:
@@ -925,6 +926,13 @@ int main(int argc, char *argv[])
 		case O(MANAGE,AddSpare): /* add drive - never re-add */
 			devmode = 'S';
 			continue;
+		case O(MANAGE,AddJournal): /* add journal */
+			if (s.journaldisks && (s.level < 4 || s.level > 6)) {
+				pr_err("--add-journal is only supported for RAID level 4/5/6.\n");
+				exit(2);
+			}
+			devmode = 'j';
+			continue;
 		case O(MANAGE,ReAdd):
 			devmode = 'A';
 			continue;