Assemble: when forcing a single-degraded RAID6 array, trigger a 'repair'.

When an active/degraded RAID6 array is force-started we clear the
'active' flag, but it is still possible that some parity is
no in sync.  This is because there are two parity block.
It would be nice to be able to tell the kernel "P is OK, Q maybe not".
But that is not possible.

So when we force-assemble such an array, trigger a 'repair' to fix up
any errant Q blocks.

This is not ideal as a restart during the repair will not be continued
after the restart, but it is the best we can do without kernel help.

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

1 files changed, 23 insertions, 6 deletions

diff --git a/Assemble.c b/Assemble.c
index c927c209..dab4e6b8 100644
--- a/Assemble.c
+++ b/Assemble.c
@@ -883,7 +883,8 @@ static int start_array(int mdfd,
 		       unsigned int rebuilding_cnt,
 		       struct context *c,
 		       int clean, char *avail,
-		       int start_partial_ok
+		       int start_partial_ok,
+		       int was_forced
 	)
 {
 	int rv;
@@ -1064,6 +1065,17 @@ static int start_array(int mdfd,
 					}
 				}
 			}
+			printf("l=%d o=%d r=%d w=%d\n",content->array.level,
+			       okcnt, content->array.raid_disks, was_forced);
+			if (content->array.level == 6 &&
+			    okcnt + 1 == (unsigned)content->array.raid_disks &&
+			    was_forced) {
+				struct mdinfo *sra = sysfs_read(mdfd, NULL, 0);
+				if (sra)
+					sysfs_set_str(sra, NULL,
+						      "sync_action", "repair");
+				sysfs_free(sra);
+			}
 			return 0;
 		}
 		pr_err("failed to RUN_ARRAY %s: %s\n",
@@ -1190,6 +1202,7 @@ int Assemble(struct supertype *st, char *mddev,
 	int devcnt;
 	unsigned int okcnt, sparecnt, rebuilding_cnt, replcnt;
 	int i;
+	int was_forced = 0;
 	int most_recent = 0;
 	int chosen_drive;
 	int change = 0;
@@ -1485,10 +1498,13 @@ try_again:
 		}
 	}
 	free(devmap);
-	if (c->force)
-		okcnt += force_array(content, devices, best, bestcnt,
-				     avail, most_recent, st, c);
-
+	if (c->force) {
+		int force_ok = force_array(content, devices, best, bestcnt,
+					   avail, most_recent, st, c);
+		okcnt += force_ok;
+		if (force_ok)
+			was_forced = 1;
+	}
 	/* Now we want to look at the superblock which the kernel will base things on
 	 * and compare the devices that we think are working with the devices that the
 	 * superblock thinks are working.
@@ -1584,6 +1600,7 @@ try_again:
 		change += st->ss->update_super(st, content, "force-array",
 					       devices[chosen_drive].devname, c->verbose,
 					       0, NULL);
+		was_forced = 1;
 		clean = 1;
 	}
 
@@ -1689,7 +1706,7 @@ try_again:
 			 chosen_drive, devices, okcnt, sparecnt,
 			 rebuilding_cnt,
 			 c,
-			 clean, avail, start_partial_ok);
+			 clean, avail, start_partial_ok, was_forced);
 	if (rv == 1 && !pre_exist)
 		ioctl(mdfd, STOP_ARRAY, NULL);
 	free(devices);