If you create a two drive raid1 array with one device writemostly, then
fail the readwrite drive, when you add a new device, it will get the
writemostly bit copied out of the remaining device's superblock into
it's own. You can then remove the new drive and readd it as readwrite,
which will work for the readd, but it leaves the stale WriteMostly1 bit
in devflags resulting in the device going back to writemostly on the
next assembly.
The fix is to make sure that A) when we readd a device and we might have
filled the st->sb info from a running device instead of the device being
readded, then clear/set the WriteMostly1 bit in the super1 struct in
addition to setting the disk state (ditto for super0, but slightly
different mechanism) and B) when adding a clean device to an array (when
we most certainly did copy the superblock info from an existing device),
then clear any writemostly bits.
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
diff -up mdadm-3.2.2/Manage.c.writemostly mdadm-3.2.2/Manage.c
--- mdadm-3.2.2/Manage.c.writemostly 2011-06-13 22:50:01.000000000 -0400
+++ mdadm-3.2.2/Manage.c 2011-07-27 14:12:18.629889841 -0400
@@ -741,11 +741,24 @@ int Manage_subdevs(char *devname, int fd
remove_partitions(tfd);
close(tfd);
tfd = -1;
- if (update) {
+ if (update || dv->writemostly > 0) {
int rv = -1;
tfd = dev_open(dv->devname, O_RDWR);
+ if (tfd < 0) {
+ fprintf(stderr, Name ": failed to open %s for"
+ " superblock update during re-add\n", dv->devname);
+ return 1;
+ }
- if (tfd >= 0)
+ if (dv->writemostly == 1)
+ rv = st->ss->update_super(
+ st, NULL, "writemostly",
+ devname, verbose, 0, NULL);
+ if (dv->writemostly == 2)
+ rv = st->ss->update_super(
+ st, NULL, "readwrite",
+ devname, verbose, 0, NULL);
+ if (update)
rv = st->ss->update_super(
st, NULL, update,
devname, verbose, 0, NULL);
diff -up mdadm-3.2.2/mdadm.h.writemostly mdadm-3.2.2/mdadm.h
--- mdadm-3.2.2/mdadm.h.writemostly 2011-07-27 14:12:28.800779575 -0400
+++ mdadm-3.2.2/mdadm.h 2011-07-27 14:04:34.669932148 -0400
@@ -646,6 +646,8 @@ extern struct superswitch {
* linear-grow-new - add a new device to a linear array, but don't
* change the size: so superblock still matches
* linear-grow-update - now change the size of the array.
+ * writemostly - set the WriteMostly1 bit in the superblock devflags
+ * readwrite - clear the WriteMostly1 bit in the superblock devflags
*/
int (*update_super)(struct supertype *st, struct mdinfo *info,
char *update,
diff -up mdadm-3.2.2/super0.c.writemostly mdadm-3.2.2/super0.c
--- mdadm-3.2.2/super0.c.writemostly 2011-06-17 01:15:50.000000000 -0400
+++ mdadm-3.2.2/super0.c 2011-07-27 14:12:18.655889559 -0400
@@ -570,6 +570,10 @@ static int update_super0(struct supertyp
sb->state &= ~(1<<MD_SB_BITMAP_PRESENT);
} else if (strcmp(update, "_reshape_progress")==0)
sb->reshape_position = info->reshape_progress;
+ else if (strcmp(update, "writemostly")==0)
+ sb->state |= (1<<MD_DISK_WRITEMOSTLY);
+ else if (strcmp(update, "readwrite")==0)
+ sb->state &= ~(1<<MD_DISK_WRITEMOSTLY);
else
rv = -1;
@@ -688,6 +692,8 @@ static int add_to_super0(struct supertyp
dk->minor = dinfo->minor;
dk->raid_disk = dinfo->raid_disk;
dk->state = dinfo->state;
+ /* In case our source disk was writemostly, don't copy that bit */
+ dk->state &= ~(1<<MD_DISK_WRITEMOSTLY);
sb->this_disk = sb->disks[dinfo->number];
sb->sb_csum = calc_sb0_csum(sb);
diff -up mdadm-3.2.2/super1.c.writemostly mdadm-3.2.2/super1.c
--- mdadm-3.2.2/super1.c.writemostly 2011-06-17 01:15:50.000000000 -0400
+++ mdadm-3.2.2/super1.c 2011-07-27 14:12:18.656889548 -0400
@@ -803,6 +803,10 @@ static int update_super1(struct supertyp
__le64_to_cpu(sb->data_size));
} else if (strcmp(update, "_reshape_progress")==0)
sb->reshape_position = __cpu_to_le64(info->reshape_progress);
+ else if (strcmp(update, "writemostly")==0)
+ sb->devflags |= WriteMostly1;
+ else if (strcmp(update, "readwrite")==0)
+ sb->devflags &= ~WriteMostly1;
else
rv = -1;
@@ -923,6 +927,7 @@ static int add_to_super1(struct supertyp
sb->max_dev = __cpu_to_le32(dk->number+1);
sb->dev_number = __cpu_to_le32(dk->number);
+ sb->devflags = 0; /* don't copy another disks flags */
sb->sb_csum = calc_sb_1_csum(sb);
dip = (struct devinfo **)&st->info;
