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 every 3Meg.
Signed-off-by: Neil Brown <[email protected]>
### Diffstat output
./drivers/md/raid5.c | 53 ++++++++++++++++++++++++++++++++++---------
./include/linux/raid/raid5.h | 3 ++
2 files changed, 45 insertions(+), 11 deletions(-)
diff ./drivers/md/raid5.c~current~ ./drivers/md/raid5.c
--- ./drivers/md/raid5.c~current~ 2006-01-24 11:19:21.000000000 +1100
+++ ./drivers/md/raid5.c 2006-01-24 11:26:16.000000000 +1100
@@ -1748,8 +1748,9 @@ static int make_request(request_queue_t
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 {
@@ -1757,6 +1758,13 @@ static int make_request(request_queue_t
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,
@@ -1765,7 +1773,6 @@ static int make_request(request_queue_t
(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)) {
@@ -1863,6 +1870,7 @@ static sector_t sync_request(mddev_t *md
*/
int i;
int dd_idx;
+ sector_t writepos, safepos, gap;
if (sector_nr == 0 &&
conf->expand_progress != 0) {
@@ -1873,15 +1881,36 @@ static sector_t sync_request(mddev_t *md
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;
@@ -2312,6 +2341,7 @@ 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);
@@ -2599,6 +2629,7 @@ static int raid5_reshape(mddev_t *mddev,
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 ./include/linux/raid/raid5.h~current~ ./include/linux/raid/raid5.h
--- ./include/linux/raid/raid5.h~current~ 2006-01-24 11:19:21.000000000 +1100
+++ ./include/linux/raid/raid5.h 2006-01-24 11:26:16.000000000 +1100
@@ -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 */
-
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