On Wed, Nov 08 2017, Shaohua Li wrote:
> On Thu, Nov 02, 2017 at 09:40:50AM +0100, Tomasz Majchrzak wrote:
>> 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.
>
> Neil,
> can you send me a formal patch for this? or I can just fold this into your
> original patch.
If you can fold it in, that would be great. Otherwise it may be a while
before I get to it.
Thanks,
NeilBrown
Attachment:
signature.asc
Description: PGP signature
