On Wed, Nov 01, 2017 at 12:13:22PM +1100, NeilBrown wrote:
> On Tue, Oct 31 2017, Tomasz Majchrzak wrote:
>
> > On Tue, Oct 17, 2017 at 04:18:36PM +1100, NeilBrown wrote:
> >> The ->recovery_offset shows how much of a non-InSync device is actually
> >> in sync - how much has been recoveryed.
> >>
> >> When performing a recovery, ->curr_resync and ->curr_resync_completed
> >> follow the device address being recovered and so can be used to update
> >> ->recovery_offset.
> >>
> >> When performing a reshape, ->curr_resync* might follow the device
> >> addresses (raid5) or might follow array addresses (raid10), so cannot
> >> in general be used to set ->recovery_offset. When reshaping backwards,
> >> ->curre_resync* measures from the *end* of the array-or-device, so is
> >> particularly unhelpful.
> >>
> >> So change the common code in md.c to only use ->curr_resync_complete
> >> for the simple recovery case, and add code to raid5.c to update
> >> ->recovery_offset during a forwards reshape.
> >>
> >> Signed-off-by: NeilBrown <neilb@xxxxxxxx>
> >> ---
> >> drivers/md/md.c | 32 +++++++++++++++++++++-----------
> >> drivers/md/raid5.c | 18 ++++++++++++++++++
> >> 2 files changed, 39 insertions(+), 11 deletions(-)
> >>
> >> diff --git a/drivers/md/md.c b/drivers/md/md.c
> >> index a9f1352b3849..d1dfc9879368 100644
> >> --- a/drivers/md/md.c
> >> +++ b/drivers/md/md.c
> >> @@ -2453,10 +2453,17 @@ void md_update_sb(struct mddev *mddev, int force_change)
> >> }
> >> }
> >>
> >> - /* First make sure individual recovery_offsets are correct */
> >> + /* First make sure individual recovery_offsets are correct
> >> + * curr_resync_completed can only be used during recovery.
> >> + * During reshape/resync it might use array-addresses rather
> >> + * that device addresses.
> >> + */
> >> rdev_for_each(rdev, mddev) {
> >> if (rdev->raid_disk >= 0 &&
> >> mddev->delta_disks >= 0 &&
> >> + test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
> >> + test_bit(MD_RECOVERY_RECOVER, &mddev->recovery) &&
> >> + !test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
> >> !test_bit(Journal, &rdev->flags) &&
> >> !test_bit(In_sync, &rdev->flags) &&
> >> mddev->curr_resync_completed > rdev->recovery_offset)
> >> @@ -8507,16 +8514,19 @@ void md_do_sync(struct md_thread *thread)
> >> } else {
> >> if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
> >> mddev->curr_resync = MaxSector;
> >> - rcu_read_lock();
> >> - rdev_for_each_rcu(rdev, mddev)
> >> - if (rdev->raid_disk >= 0 &&
> >> - mddev->delta_disks >= 0 &&
> >> - !test_bit(Journal, &rdev->flags) &&
> >> - !test_bit(Faulty, &rdev->flags) &&
> >> - !test_bit(In_sync, &rdev->flags) &&
> >> - rdev->recovery_offset < mddev->curr_resync)
> >> - rdev->recovery_offset = mddev->curr_resync;
> >> - rcu_read_unlock();
> >> + if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
> >> + test_bit(MD_RECOVERY_RECOVER, &mddev->recovery)) {
> >> + rcu_read_lock();
> >> + rdev_for_each_rcu(rdev, mddev)
> >> + if (rdev->raid_disk >= 0 &&
> >> + mddev->delta_disks >= 0 &&
> >> + !test_bit(Journal, &rdev->flags) &&
> >> + !test_bit(Faulty, &rdev->flags) &&
> >> + !test_bit(In_sync, &rdev->flags) &&
> >> + rdev->recovery_offset < mddev->curr_resync)
> >> + rdev->recovery_offset = mddev->curr_resync;
> >> + rcu_read_unlock();
> >> + }
> >> }
> >> }
> >> skip:
> >> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> >> index a8df52130f8a..89ad79614309 100644
> >> --- a/drivers/md/raid5.c
> >> +++ b/drivers/md/raid5.c
> >> @@ -5739,6 +5739,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
> >> */
> >> struct r5conf *conf = mddev->private;
> >> struct stripe_head *sh;
> >> + struct md_rdev *rdev;
> >> sector_t first_sector, last_sector;
> >> int raid_disks = conf->previous_raid_disks;
> >> int data_disks = raid_disks - conf->max_degraded;
> >> @@ -5861,6 +5862,15 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
> >> return 0;
> >> mddev->reshape_position = conf->reshape_progress;
> >> mddev->curr_resync_completed = sector_nr;
> >> + if (!mddev->reshape_backwards)
> >> + /* Can update recovery_offset */
> >> + rdev_for_each(rdev, mddev)
> >> + if (rdev->raid_disk >= 0 &&
> >> + !test_bit(Journal, &rdev->flags) &&
> >> + !test_bit(In_sync, &rdev->flags) &&
> >> + rdev->recovery_offset < sector_nr)
> >> + rdev->recovery_offset = sector_nr;
> >> +
> >> conf->reshape_checkpoint = jiffies;
> >> set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
> >> md_wakeup_thread(mddev->thread);
> >> @@ -5959,6 +5969,14 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
> >> goto ret;
> >> mddev->reshape_position = conf->reshape_progress;
> >> mddev->curr_resync_completed = sector_nr;
> >> + if (!mddev->reshape_backwards)
> >> + /* Can update recovery_offset */
> >> + rdev_for_each(rdev, mddev)
> >> + if (rdev->raid_disk >= 0 &&
> >> + !test_bit(Journal, &rdev->flags) &&
> >> + !test_bit(In_sync, &rdev->flags) &&
> >> + rdev->recovery_offset < sector_nr)
> >> + rdev->recovery_offset = sector_nr;
> >> conf->reshape_checkpoint = jiffies;
> >> set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
> >> md_wakeup_thread(mddev->thread);
> >>
> >>
> >> --
> >
> > Hi,
> >
> > This patch has caused a regression in following IMSM RAID scenario:
>
> That's unfortunate.
>
> >
> > mdadm --create /dev/md/imsm0 --metadata=imsm --raid-devices=4 /dev/nvme[0-3]n1 --run
> > mdadm --create /dev/md/r10 --level=10 --size=100M --raid-devices=4 /dev/nvme[0-3]n1 --run --assume-clean
> >
> > MDADM_EXPERIMENTAL=1 mdadm --grow /dev/md/r10 --level=0
> > MDADM_EXPERIMENTAL=1 mdadm --grow /dev/md/imsm0 --raid-devices=4
> >
> > cat /proc/mdstat
> > Personalities : [raid10] [raid0] [raid6] [raid5] [raid4]
> > md126 : active raid4 nvme0n1[3] nvme2n1[2] nvme1n1[1]
> > 409600 blocks super external:/md127/0 level 4, 128k chunk, algorithm 0 [5/3] [UU_U_]
> >
> > md127 : inactive nvme3n1[3](S) nvme2n1[2](S) nvme1n1[1](S) nvme0n1[0](S)
> > 4420 blocks super external:imsm
>
> Why isn't nvme3n1 in md126? Did it not get added, or did it get removed
> for some reason?
> If it wasn't added, raid5_start_reshape() would have failed, so I guess
> it must have been removed??
It got removed. It's in the array during the reshape:
cat /proc/mdstat
Personalities : [raid10] [raid0] [raid6] [raid5] [raid4] [raid1]
md126 : active raid4 nvme3n1[4] nvme0n1[3] nvme2n1[2] nvme1n1[1]
4194304 blocks super external:-md127/0 level 4, 128k chunk, algorithm 5 [5/4] [UU_U_]
[===>.................] reshape = 16.6% (350476/2097152) finish=0.1min speed=175238K/sec
md127 : inactive nvme3n1[3](S) nvme2n1[2](S) nvme1n1[1](S) nvme0n1[0](S)
4420 blocks super external:imsm
>
> >
> > The array should have been reshaped to 4-disk RAID0 but it has failed in
> > the middle of reshape as RAID4.
> >
> > Following condition is not true for above scenario:
> >
> >> + if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
> >> + test_bit(MD_RECOVERY_RECOVER, &mddev->recovery)) {
>
> No, it isn't meant to be. This code doesn't work reliably in the
> reshape case. When reshaping raid5 (or raid4), reshape_request updates
> rdev->recovery_offset. ... maybe end_reshape needs to update it too.
>
> If you add this patch, does it help?
>
>
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 89ad79614309..a99ae1be9175 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -7964,6 +7964,7 @@ static void end_reshape(struct r5conf *conf)
> {
>
> if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
> + struct md_rdev *rdev;
>
> spin_lock_irq(&conf->device_lock);
> conf->previous_raid_disks = conf->raid_disks;
> @@ -7971,6 +7972,12 @@ static void end_reshape(struct r5conf *conf)
> smp_wmb();
> conf->reshape_progress = MaxSector;
> conf->mddev->reshape_position = MaxSector;
> + rdev_for_each(rdev, conf->mddev)
> + if (rdev->raid_disk >= 0 &&
> + !test_bit(Journal, &rdev->flags) &&
> + !test_bit(In_sync, &rdev->flags))
> + rdev->recovery_offset = MaxSector;
> +
> spin_unlock_irq(&conf->device_lock);
> wake_up(&conf->wait_for_overlap);
>
Yes, this patch fixes the problem. I have also checked that reshape position
is really stored and reshape interrupted in the middle restarts from the
last checkpoint.
Thank you,
Tomek
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