On Wed, 29 Jul 2015 17:38:42 -0700 Shaohua Li <shli@xxxxxx> wrote:
> Cache device stores data in a log structure. We need record the log
> start. Here we override md superblock recovery_offset for this purpose.
> This field of a cache device is meaningless otherwise.
>
> Signed-off-by: Shaohua Li <shli@xxxxxx>
> ---
> drivers/md/md.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index fd84f16..9861f34 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -1664,6 +1664,7 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)
> "cache feature, ignoring the device\n");
> return -EINVAL;
> }
> + rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
> set_bit(WriteCache, &rdev->flags);
> break;
> default:
> @@ -1830,6 +1831,9 @@ static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
> sb->dev_roles[i] = cpu_to_le16(0xffff);
> }
>
> + if (test_bit(WriteCache, &rdev->flags))
> + sb->recovery_offset = cpu_to_le64(rdev->recovery_offset);
> +
I would much rather this was a little earlier in the function,
near where recovery_offset is set for non-InSync devices.
i.e. immediately after:
if (rdev->raid_disk >= 0 &&
!test_bit(In_sync, &rdev->flags)) {
sb->feature_map |=
cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET);
sb->recovery_offset =
cpu_to_le64(rdev->recovery_offset);
if (rdev->saved_raid_disk >= 0 && mddev->bitmap)
sb->feature_map |=
cpu_to_le32(MD_FEATURE_RECOVERY_BITMAP);
}
Maybe we could always copy recovery_offset from rdev to sb, and then
just set whichever feature flags are relevant - if any. Or maybe not.
Thanks,
NeilBrown
> sb->sb_csum = calc_sb_1_csum(sb);
> }
>
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