[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 <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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 @@
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 @@
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 @@
(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 @@
*/
int i;
int dd_idx;
+ sector_t writepos, safepos, gap;
if (sector_nr == 0 &&
conf->expand_progress != 0) {
@@ -1887,15 +1895,36 @@
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 @@
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 @@
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 @@
/* 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 */