[PATCH md 000 of 3] Introduction

[PATCH md 000 of 3] Introduction

[NeilBrown]

Here are three patches for md in 2.6.13-mm1

The first (embarassment) gets sb_size initialisation REALLY right.
 I did more testing with mdadm-v1 and found hot-add wasn't working
 either.  This patch definitely covers all cases.

The other two fix problems with raid10 when enough drives fails that
not all block are available.  It was particularly a problem as recovery
would BUG-out, but other issues are fixed to.

These patches are tested and suitable for early release to Linus.

Thanks,
NeilBrown


 [PATCH md 001 of 3] Really get sb_size setting right in all cases.	
 [PATCH md 002 of 3] Fix raid10 assembly when too many devices are missing.
 [PATCH md 003 of 3] Fix BUG when raid10 rebuilds without enough drives.

[PATCH md 001 of 3] Really get sb_size setting right in all cases.

[NeilBrown]

There was another case where sb_size wasn't being set, so
instead do the sensible thing and set if when filling in the
content of a superblock.  That ensures that whenever we
write a superblock, the sb_size MUST be set.

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

### Diffstat output
 ./drivers/md/md.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff ./drivers/md/md.c~current~ ./drivers/md/md.c
--- ./drivers/md/md.c~current~	2005-09-02 19:29:31.000000000 +1000
+++ ./drivers/md/md.c	2005-09-05 14:47:45.000000000 +1000
@@ -712,6 +712,8 @@ static void super_90_sync(mddev_t *mddev
 	int i;
 	int active=0, working=0,failed=0,spare=0,nr_disks=0;
 
+	rdev->sb_size = MD_SB_BYTES;
+
 	sb = (mdp_super_t*)page_address(rdev->sb_page);
 
 	memset(sb, 0, sizeof(*sb));
@@ -2303,8 +2305,6 @@ static int add_new_disk(mddev_t * mddev,
 		else
 			rdev->in_sync = 0;
 
-		rdev->sb_size = MD_SB_BYTES;
-
 		if (info->state & (1<<MD_DISK_WRITEMOSTLY))
 			set_bit(WriteMostly, &rdev->flags);
 

[PATCH md 002 of 3] Fix raid10 assembly when too many devices are missing.

[NeilBrown]

if you try to assemble an array with too many missing devices,
raid10 will now reject the attempt, instead of allowing it.

Also check when hot-adding a drive and refuse the hot-add if 
the array is beyond hope.

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

### Diffstat output
 ./drivers/md/raid10.c |   30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff ./drivers/md/raid10.c~current~ ./drivers/md/raid10.c
--- ./drivers/md/raid10.c~current~	2005-09-06 13:05:59.000000000 +1000
+++ ./drivers/md/raid10.c	2005-09-06 13:09:22.000000000 +1000
@@ -906,6 +906,27 @@ static void close_sync(conf_t *conf)
 	conf->r10buf_pool = NULL;
 }
 
+/* check if there are enough drives for
+ * every block to appear on atleast one
+ */
+static int enough(conf_t *conf)
+{
+	int first = 0;
+
+	do {
+		int n = conf->copies;
+		int cnt = 0;
+		while (n--) {
+			if (conf->mirrors[first].rdev)
+				cnt++;
+			first = (first+1) % conf->raid_disks;
+		}
+		if (cnt == 0)
+			return 0;
+	} while (first != 0);
+	return 1;
+}
+
 static int raid10_spare_active(mddev_t *mddev)
 {
 	int i;
@@ -944,6 +965,8 @@ static int raid10_add_disk(mddev_t *mdde
 		 * very different from resync
 		 */
 		return 0;
+	if (!enough(conf))
+		return 0;
 
 	for (mirror=0; mirror < mddev->raid_disks; mirror++)
 		if ( !(p=conf->mirrors+mirror)->rdev) {
@@ -1684,9 +1707,10 @@ static int run(mddev_t *mddev)
 	init_waitqueue_head(&conf->wait_idle);
 	init_waitqueue_head(&conf->wait_resume);
 
-	if (!conf->working_disks) {
-		printk(KERN_ERR "raid10: no operational mirrors for %s\n",
-			mdname(mddev));
+	/* need to check that every block has at least one working mirror */
+	if (!enough(conf)) {
+		printk(KERN_ERR "raid10: not enough operational mirrors for %s\n",
+		       mdname(mddev));
 		goto out_free_conf;
 	}
 

[PATCH md 003 of 3] Fix BUG when raid10 rebuilds without enough drives.

[NeilBrown]

This shouldn't be a BUG.  We should cope.

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

### Diffstat output
 ./drivers/md/raid10.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff ./drivers/md/raid10.c~current~ ./drivers/md/raid10.c
--- ./drivers/md/raid10.c~current~	2005-09-06 13:09:22.000000000 +1000
+++ ./drivers/md/raid10.c	2005-09-06 13:11:23.000000000 +1000
@@ -1474,7 +1474,13 @@ static sector_t sync_request(mddev_t *md
 					}
 				}
 				if (j == conf->copies) {
-					BUG();
+					/* Cannot recover, so abort the recovery */
+					put_buf(r10_bio);
+					r10_bio = rb2;
+					if (!test_and_set_bit(MD_RECOVERY_ERR, &mddev->recovery))
+						printk(KERN_INFO "raid10: %s: insufficient working devices for recovery.\n",
+						       mdname(mddev));
+					break;
 				}
 			}
 		if (biolist == NULL) {