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[PATCH] md: Only checkpoint expansion progress occasionally

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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 <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
NeilBrown 2006-03-27 01:18:12 -08:00 committed by Linus Torvalds
parent f67055780c
commit b578d55fdd
2 changed files with 44 additions and 10 deletions
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51
drivers/md/raid5.c
View file

@ -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;
/* 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;
mddev->sb_dirty = 1;
md_wakeup_thread(mddev->thread);
wait_event(mddev->sb_wait, mddev->sb_dirty == 0 ||
kthread_should_stop());
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.

3
include/linux/raid/raid5.h
View file

@ -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 */