From 97e4f42d62badb0f9fbc27c013e89bc1336a03bc Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 31 Mar 2009 14:33:13 +1100 Subject: md: occasionally checkpoint drive recovery to reduce duplicate effort after a crash Version 1.x metadata has the ability to record the status of a partially completed drive recovery. However we only update that record on a clean shutdown. It would be nice to update it on unclean shutdowns too, particularly when using a bitmap that removes much to the 'sync' effort after an unclean shutdown. One complication with checkpointing recovery is that we only know where we are up to in terms of IO requests started, not which ones have completed. And we need to know what has completed to record how much is recovered. So occasionally pause the recovery until all submitted requests are completed, then update the record of where we are up to. When we have a bitmap, we already do that pause occasionally to keep the bitmap up-to-date. So enhance that code to record the recovery offset and schedule a superblock update. And when there is no bitmap, just pause 16 times during the resync to do a checkpoint. '16' is a fairly arbitrary number. But we don't really have any good way to judge how often is acceptable, and it seems like a reasonable number for now. Signed-off-by: NeilBrown --- drivers/md/bitmap.c | 2 ++ drivers/md/md.c | 27 +++++++++++++++++++++++---- drivers/md/md.h | 7 +++++++ 3 files changed, 32 insertions(+), 4 deletions(-) (limited to 'drivers') diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c index 623292a5473..5d64da99080 100644 --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -1470,6 +1470,8 @@ void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector) wait_event(bitmap->mddev->recovery_wait, atomic_read(&bitmap->mddev->recovery_active) == 0); + bitmap->mddev->curr_resync_completed = bitmap->mddev->curr_resync; + set_bit(MD_CHANGE_CLEAN, &bitmap->mddev->flags); sector &= ~((1ULL << CHUNK_BLOCK_SHIFT(bitmap)) - 1); s = 0; while (s < sector && s < bitmap->mddev->resync_max_sectors) { diff --git a/drivers/md/md.c b/drivers/md/md.c index aad0ac54bf9..8ea208847a6 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -1324,10 +1324,15 @@ static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev) } if (rdev->raid_disk >= 0 && - !test_bit(In_sync, &rdev->flags) && - rdev->recovery_offset > 0) { - sb->feature_map |= cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET); - sb->recovery_offset = cpu_to_le64(rdev->recovery_offset); + !test_bit(In_sync, &rdev->flags)) { + if (mddev->curr_resync_completed > rdev->recovery_offset) + rdev->recovery_offset = mddev->curr_resync_completed; + if (rdev->recovery_offset > 0) { + sb->feature_map |= + cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET); + sb->recovery_offset = + cpu_to_le64(rdev->recovery_offset); + } } if (mddev->reshape_position != MaxSector) { @@ -6072,6 +6077,18 @@ void md_do_sync(mddev_t *mddev) } if (kthread_should_stop()) goto interrupted; + + if (mddev->curr_resync > mddev->curr_resync_completed && + (mddev->curr_resync - mddev->curr_resync_completed) + > (max_sectors >> 4)) { + /* time to update curr_resync_completed */ + blk_unplug(mddev->queue); + wait_event(mddev->recovery_wait, + atomic_read(&mddev->recovery_active) == 0); + mddev->curr_resync_completed = + mddev->curr_resync; + set_bit(MD_CHANGE_CLEAN, &mddev->flags); + } sectors = mddev->pers->sync_request(mddev, j, &skipped, currspeed < speed_min(mddev)); if (sectors == 0) { @@ -6205,6 +6222,8 @@ static int remove_and_add_spares(mddev_t *mddev) mdk_rdev_t *rdev; int spares = 0; + mddev->curr_resync_completed = 0; + list_for_each_entry(rdev, &mddev->disks, same_set) if (rdev->raid_disk >= 0 && !test_bit(Blocked, &rdev->flags) && diff --git a/drivers/md/md.h b/drivers/md/md.h index e78b3c1d55f..bede26c9d4a 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -159,6 +159,13 @@ struct mddev_s struct mdk_thread_s *thread; /* management thread */ struct mdk_thread_s *sync_thread; /* doing resync or reconstruct */ sector_t curr_resync; /* last block scheduled */ + /* As resync requests can complete out of order, we cannot easily track + * how much resync has been completed. So we occasionally pause until + * everything completes, then set curr_resync_completed to curr_resync. + * As such it may be well behind the real resync mark, but it is a value + * we are certain of. + */ + sector_t curr_resync_completed; unsigned long resync_mark; /* a recent timestamp */ sector_t resync_mark_cnt;/* blocks written at resync_mark */ sector_t curr_mark_cnt; /* blocks scheduled now */ -- cgit v1.2.3-18-g5258