md: allow v0.91 metadata to record devices as being active but not in-sync.

This is a combination that didn't really make sense before.
However when a reshape is converting e.g. raid5 -> raid6, the extra
device is not fully in-sync, but is certainly active and contains
important data.
So allow that start to be meaningful and in particular get
the 'recovery_offset' value (which is needed for any non-in-sync
active device) from the reshape_position.

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

1 files changed, 25 insertions, 6 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 01b9a0fd16e0..b182f86a19dd 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -944,6 +944,14 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
                             desc->raid_disk < mddev->raid_disks */) {
                         set_bit(In_sync, &rdev->flags);
                         rdev->raid_disk = desc->raid_disk;
+                } else if (desc->state & (1<<MD_DISK_ACTIVE)) {
+                        /* active but not in sync implies recovery up to
+                         * reshape position.  We don't know exactly where
+                         * that is, so set to zero for now */
+                        if (mddev->minor_version >= 91) {
+                                rdev->recovery_offset = 0;
+                                rdev->raid_disk = desc->raid_disk;
+                        }
                 }
                 if (desc->state & (1<<MD_DISK_WRITEMOSTLY))
                         set_bit(WriteMostly, &rdev->flags);
@@ -1032,8 +1040,19 @@ static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
         list_for_each_entry(rdev2, &mddev->disks, same_set) {
                 mdp_disk_t *d;
                 int desc_nr;
-                if (rdev2->raid_disk >= 0 && test_bit(In_sync, &rdev2->flags)
-                    && !test_bit(Faulty, &rdev2->flags))
+                int is_active = test_bit(In_sync, &rdev2->flags);
+
+                if (rdev2->raid_disk >= 0 &&
+                    sb->minor_version >= 91)
+                        /* we have nowhere to store the recovery_offset,
+                         * but if it is not below the reshape_position,
+                         * we can piggy-back on that.
+                         */
+                        is_active = 1;
+                if (rdev2->raid_disk < 0 ||
+                    test_bit(Faulty, &rdev2->flags))
+                        is_active = 0;
+                if (is_active)
                         desc_nr = rdev2->raid_disk;
                 else
                         desc_nr = next_spare++;
@@ -1043,16 +1062,16 @@ static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
                 d->number = rdev2->desc_nr;
                 d->major = MAJOR(rdev2->bdev->bd_dev);
                 d->minor = MINOR(rdev2->bdev->bd_dev);
-                if (rdev2->raid_disk >= 0 && test_bit(In_sync, &rdev2->flags)
-                    && !test_bit(Faulty, &rdev2->flags))
+                if (is_active)
                         d->raid_disk = rdev2->raid_disk;
                 else
                         d->raid_disk = rdev2->desc_nr; /* compatibility */
                 if (test_bit(Faulty, &rdev2->flags))
                         d->state = (1<<MD_DISK_FAULTY);
-                else if (test_bit(In_sync, &rdev2->flags)) {
+                else if (is_active) {
                         d->state = (1<<MD_DISK_ACTIVE);
-                        d->state |= (1<<MD_DISK_SYNC);
+                        if (test_bit(In_sync, &rdev2->flags))
+                                d->state |= (1<<MD_DISK_SYNC);
                         active++;
                         working++;
                 } else {