Enhance raid4 support: --assemble and --monitor wasn't quite happy with it.

From: Doug Ledford <dledford@redhat.com>

This one actually does a couple things.  Mainly related to raid4, but
kinda touches other raid levels some.

When creating a raid4 array, treat it like a raid5 array in that we
create it in degraded mode by default and add the last disk as a spare.
Besides speeding things up, this has a second effect that it makes mdadm
more consistent.  In order to create a degraded raid5 array, you need
only passing missing as one of the devices.  For a degraded raid4 array,
prior to this patch, you must pass assume-clean or else it refuses to
create the array.  Even force won't make it work without assume-clean.
With the patch, raid4 behaves identical to raid5.

Separate from that, the monitor functionality completely ignores raid4
arrays.  That seems to stem from the code that checks to see if the
array is part of a long list of types.  It seems easier to check which
array types *aren't* redundant instead of listing the ones that are
redundant and missing some of them.  This makes the monitor service
actually watch raid4 arrays.

3 files changed, 10 insertions, 8 deletions

diff --git a/Create.c b/Create.c
index 08972ae..3e6f1af 100644
--- a/Create.c
+++ b/Create.c
@@ -315,12 +315,13 @@ int Create(struct supertype *st, char *mddev, int mdfd,
 		}
 	}
 
-	/* If this is  raid5, we want to configure the last active slot
+	/* If this is raid4/5, we want to configure the last active slot
 	 * as missing, so that a reconstruct happens (faster than re-parity)
 	 * FIX: Can we do this for raid6 as well?
 	 */
 	if (assume_clean==0 && force == 0 && first_missing >= raiddisks) {
 		switch ( level ) {
+		case 4:
 		case 5:
 			insert_point = raiddisks-1;
 			sparedisks++;
@@ -345,7 +346,7 @@ int Create(struct supertype *st, char *mddev, int mdfd,
 		array.md_minor = minor(stb.st_rdev);
 	array.not_persistent = 0;
 	/*** FIX: Need to do something about RAID-6 here ***/
-	if ( ( (level == 5) &&
+	if ( ( (level == 4 || level == 5) &&
 	       (insert_point < raiddisks || first_missing < raiddisks) )
 	     ||
 	     ( level == 6 && missing_disks == 2)
diff --git a/Monitor.c b/Monitor.c
index 79a88a7..91f02a4 100644
--- a/Monitor.c
+++ b/Monitor.c
@@ -245,8 +245,10 @@ int Monitor(mddev_dev_t devlist,
 				close(fd);
 				continue;
 			}
-			if (array.level != 1 && array.level != 5 && array.level != -4 &&
-				array.level != 6 && array.level != 10) {
+			/* It's much easier to list what array levels can't
+			 * have a device disappear than all of them that can
+			 */
+			if (array.level == 0 || array.level == -1) {
 				if (!st->err)
 					alert("DeviceDisappeared", dev, "Wrong-Level",
 					      mailaddr, mailfrom, alert_cmd, dosyslog);
@@ -401,9 +403,8 @@ int Monitor(mddev_dev_t devlist,
 			struct mdstat_ent *mse;
 			for (mse=mdstat; mse; mse=mse->next) 
 				if (mse->devnum != MAXINT &&
-				    (strcmp(mse->level, "raid1")==0 ||
-				     strcmp(mse->level, "raid5")==0 ||
-				     strcmp(mse->level, "multipath")==0)
+				    (strcmp(mse->level, "raid0")!=0 &&
+				     strcmp(mse->level, "linear")!=0)
 					) {
 					struct state *st = malloc(sizeof *st);
 					mdu_array_info_t array;
diff --git a/tests/00raid4 b/tests/00raid4
index 3618aa9..ddb16b1 100644
--- a/tests/00raid4
+++ b/tests/00raid4
@@ -8,7 +8,7 @@ mdadm -S $md0
 
 # now with version-1 superblock
 mdadm -CR $md0 -e1 --level=raid4 -n4 $dev0 $dev1 $dev2 $dev3 
-check resync; check raid[45]
+check recovery; check raid[45]
 testdev $md0 3 $mdsize1 64
 mdadm -S $md0