md: ensure changes to 'write-mostly' are reflected in metadata.

The 'write-mostly' flag can be changed through sysfs.
With 0.90 metadata, those changes are reflected in the metadata.
For 1.x metadata, they aren't.

So fix super_1_sync to record 'write-mostly' status.

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

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1cd9bfb..9a88023 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1738,6 +1738,11 @@ static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
        sb->level = cpu_to_le32(mddev->level);
        sb->layout = cpu_to_le32(mddev->layout);
 
+       if (test_bit(WriteMostly, &rdev->flags))
+               sb->devflags |= WriteMostly1;
+       else
+               sb->devflags &= ~WriteMostly1;
+
        if (mddev->bitmap && mddev->bitmap_info.file == NULL) {
                sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_info.offset);
                sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);