From b578d55fdd80140f657130abd85aebeb345755fb Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 27 Mar 2006 01:18:12 -0800 Subject: [PATCH] [PATCH] md: Only checkpoint expansion progress occasionally Instead of checkpointing at each stripe, only checkpoint when a new write would overwrite uncheckpointed data. Block any write to the uncheckpointed area. Arbitrarily checkpoint at least every 3Meg. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/md/raid5.c | 53 ++++++++++++++++++++++++++++++++++++---------- include/linux/raid/raid5.h | 3 +++ 2 files changed, 45 insertions(+), 11 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 20ae32d6..089a326 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -1762,8 +1762,9 @@ static int make_request(request_queue_t *q, struct bio * bi) for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) { DEFINE_WAIT(w); int disks; - + retry: + prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE); if (likely(conf->expand_progress == MaxSector)) disks = conf->raid_disks; else { @@ -1771,6 +1772,13 @@ static int make_request(request_queue_t *q, struct bio * bi) disks = conf->raid_disks; if (logical_sector >= conf->expand_progress) disks = conf->previous_raid_disks; + else { + if (logical_sector >= conf->expand_lo) { + spin_unlock_irq(&conf->device_lock); + schedule(); + goto retry; + } + } spin_unlock_irq(&conf->device_lock); } new_sector = raid5_compute_sector(logical_sector, disks, disks - 1, @@ -1779,7 +1787,6 @@ static int make_request(request_queue_t *q, struct bio * bi) (unsigned long long)new_sector, (unsigned long long)logical_sector); - prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE); sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK)); if (sh) { if (unlikely(conf->expand_progress != MaxSector)) { @@ -1877,6 +1884,7 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i */ int i; int dd_idx; + sector_t writepos, safepos, gap; if (sector_nr == 0 && conf->expand_progress != 0) { @@ -1887,15 +1895,36 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i return sector_nr; } - /* Cannot proceed until we've updated the superblock... */ - wait_event(conf->wait_for_overlap, - atomic_read(&conf->reshape_stripes)==0); - mddev->reshape_position = conf->expand_progress; - - mddev->sb_dirty = 1; - md_wakeup_thread(mddev->thread); - wait_event(mddev->sb_wait, mddev->sb_dirty == 0 || - kthread_should_stop()); + /* we update the metadata when there is more than 3Meg + * in the block range (that is rather arbitrary, should + * probably be time based) or when the data about to be + * copied would over-write the source of the data at + * the front of the range. + * i.e. one new_stripe forward from expand_progress new_maps + * to after where expand_lo old_maps to + */ + writepos = conf->expand_progress + + conf->chunk_size/512*(conf->raid_disks-1); + sector_div(writepos, conf->raid_disks-1); + safepos = conf->expand_lo; + sector_div(safepos, conf->previous_raid_disks-1); + gap = conf->expand_progress - conf->expand_lo; + + if (writepos >= safepos || + gap > (conf->raid_disks-1)*3000*2 /*3Meg*/) { + /* Cannot proceed until we've updated the superblock... */ + wait_event(conf->wait_for_overlap, + atomic_read(&conf->reshape_stripes)==0); + mddev->reshape_position = conf->expand_progress; + mddev->sb_dirty = 1; + md_wakeup_thread(mddev->thread); + wait_event(mddev->sb_wait, mddev->sb_dirty == 0 || + kthread_should_stop()); + spin_lock_irq(&conf->device_lock); + conf->expand_lo = mddev->reshape_position; + spin_unlock_irq(&conf->device_lock); + wake_up(&conf->wait_for_overlap); + } for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) { int j; @@ -2322,6 +2351,7 @@ static int run(mddev_t *mddev) if (conf->expand_progress != MaxSector) { printk("...ok start reshape thread\n"); + conf->expand_lo = conf->expand_progress; atomic_set(&conf->reshape_stripes, 0); clear_bit(MD_RECOVERY_SYNC, &mddev->recovery); clear_bit(MD_RECOVERY_CHECK, &mddev->recovery); @@ -2610,6 +2640,7 @@ static int raid5_reshape(mddev_t *mddev, int raid_disks) conf->previous_raid_disks = conf->raid_disks; conf->raid_disks = raid_disks; conf->expand_progress = 0; + conf->expand_lo = 0; spin_unlock_irq(&conf->device_lock); /* Add some new drives, as many as will fit. diff --git a/include/linux/raid/raid5.h b/include/linux/raid/raid5.h index abcdf0d..914af66 100644 --- a/include/linux/raid/raid5.h +++ b/include/linux/raid/raid5.h @@ -217,6 +217,9 @@ struct raid5_private_data { /* used during an expand */ sector_t expand_progress; /* MaxSector when no expand happening */ + sector_t expand_lo; /* from here up to expand_progress it out-of-bounds + * as we haven't flushed the metadata yet + */ int previous_raid_disks; struct list_head handle_list; /* stripes needing handling */ -- 2.7.4