md/raid5: change reshape-progress measurement to cope with reshaping backwards.
When reducing the number of devices in a raid4/5/6, the reshape
process has to start at the end of the array and work down to the
beginning. So we need to handle expand_progress and expand_lo
differently.
This patch renames "expand_progress" and "expand_lo" to avoid the
implication that anything is getting bigger (expand->reshape) and
every place they are used, we make sure that they are used the right
way depending on whether delta_disks is positive or negative.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index a0f22dd..1023c4e 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3593,24 +3593,28 @@
retry:
previous = 0;
prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
- if (likely(conf->expand_progress == MaxSector))
+ if (likely(conf->reshape_progress == MaxSector))
disks = conf->raid_disks;
else {
- /* spinlock is needed as expand_progress may be
+ /* spinlock is needed as reshape_progress may be
* 64bit on a 32bit platform, and so it might be
* possible to see a half-updated value
- * Ofcourse expand_progress could change after
+ * Ofcourse reshape_progress could change after
* the lock is dropped, so once we get a reference
* to the stripe that we think it is, we will have
* to check again.
*/
spin_lock_irq(&conf->device_lock);
disks = conf->raid_disks;
- if (logical_sector >= conf->expand_progress) {
+ if (mddev->delta_disks < 0
+ ? logical_sector < conf->reshape_progress
+ : logical_sector >= conf->reshape_progress) {
disks = conf->previous_raid_disks;
previous = 1;
} else {
- if (logical_sector >= conf->expand_lo) {
+ if (mddev->delta_disks < 0
+ ? logical_sector < conf->reshape_safe
+ : logical_sector >= conf->reshape_safe) {
spin_unlock_irq(&conf->device_lock);
schedule();
goto retry;
@@ -3630,7 +3634,7 @@
sh = get_active_stripe(conf, new_sector, previous,
(bi->bi_rw&RWA_MASK));
if (sh) {
- if (unlikely(conf->expand_progress != MaxSector)) {
+ if (unlikely(conf->reshape_progress != MaxSector)) {
/* expansion might have moved on while waiting for a
* stripe, so we must do the range check again.
* Expansion could still move past after this
@@ -3641,8 +3645,10 @@
*/
int must_retry = 0;
spin_lock_irq(&conf->device_lock);
- if (logical_sector < conf->expand_progress &&
- disks == conf->previous_raid_disks)
+ if ((mddev->delta_disks < 0
+ ? logical_sector >= conf->reshape_progress
+ : logical_sector < conf->reshape_progress)
+ && disks == conf->previous_raid_disks)
/* mismatch, need to try again */
must_retry = 1;
spin_unlock_irq(&conf->device_lock);
@@ -3720,13 +3726,20 @@
int dd_idx;
sector_t writepos, safepos, gap;
- if (sector_nr == 0 &&
- conf->expand_progress != 0) {
- /* restarting in the middle, skip the initial sectors */
- sector_nr = conf->expand_progress;
+ if (sector_nr == 0) {
+ /* If restarting in the middle, skip the initial sectors */
+ if (mddev->delta_disks < 0 &&
+ conf->reshape_progress < raid5_size(mddev, 0, 0)) {
+ sector_nr = raid5_size(mddev, 0, 0)
+ - conf->reshape_progress;
+ } else if (mddev->delta_disks > 0 &&
+ conf->reshape_progress > 0)
+ sector_nr = conf->reshape_progress;
sector_div(sector_nr, new_data_disks);
- *skipped = 1;
- return sector_nr;
+ if (sector_nr) {
+ *skipped = 1;
+ return sector_nr;
+ }
}
/* we update the metadata when there is more than 3Meg
@@ -3734,28 +3747,37 @@
* 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
+ * i.e. one new_stripe along from reshape_progress new_maps
+ * to after where reshape_safe old_maps to
*/
- writepos = conf->expand_progress +
- conf->chunk_size/512*(new_data_disks);
+ writepos = conf->reshape_progress;
sector_div(writepos, new_data_disks);
- safepos = conf->expand_lo;
+ safepos = conf->reshape_safe;
sector_div(safepos, data_disks);
- gap = conf->expand_progress - conf->expand_lo;
+ if (mddev->delta_disks < 0) {
+ writepos -= conf->chunk_size/512;
+ safepos += conf->chunk_size/512;
+ gap = conf->reshape_safe - conf->reshape_progress;
+ } else {
+ writepos += conf->chunk_size/512;
+ safepos -= conf->chunk_size/512;
+ gap = conf->reshape_progress - conf->reshape_safe;
+ }
- if (writepos >= safepos ||
+ if ((mddev->delta_disks < 0
+ ? writepos < safepos
+ : writepos > safepos) ||
gap > (new_data_disks)*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->reshape_position = conf->reshape_progress;
set_bit(MD_CHANGE_DEVS, &mddev->flags);
md_wakeup_thread(mddev->thread);
wait_event(mddev->sb_wait, mddev->flags == 0 ||
kthread_should_stop());
spin_lock_irq(&conf->device_lock);
- conf->expand_lo = mddev->reshape_position;
+ conf->reshape_safe = mddev->reshape_position;
spin_unlock_irq(&conf->device_lock);
wake_up(&conf->wait_for_overlap);
}
@@ -3792,7 +3814,10 @@
release_stripe(sh);
}
spin_lock_irq(&conf->device_lock);
- conf->expand_progress = (sector_nr + i) * new_data_disks;
+ if (mddev->delta_disks < 0)
+ conf->reshape_progress -= i * new_data_disks;
+ else
+ conf->reshape_progress += i * new_data_disks;
spin_unlock_irq(&conf->device_lock);
/* Ok, those stripe are ready. We can start scheduling
* reads on the source stripes.
@@ -3823,14 +3848,14 @@
/* 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->reshape_position = conf->reshape_progress;
set_bit(MD_CHANGE_DEVS, &mddev->flags);
md_wakeup_thread(mddev->thread);
wait_event(mddev->sb_wait,
!test_bit(MD_CHANGE_DEVS, &mddev->flags)
|| kthread_should_stop());
spin_lock_irq(&conf->device_lock);
- conf->expand_lo = mddev->reshape_position;
+ conf->reshape_safe = mddev->reshape_position;
spin_unlock_irq(&conf->device_lock);
wake_up(&conf->wait_for_overlap);
}
@@ -4283,7 +4308,7 @@
conf->max_degraded = 1;
conf->algorithm = mddev->new_layout;
conf->max_nr_stripes = NR_STRIPES;
- conf->expand_progress = mddev->reshape_position;
+ conf->reshape_progress = mddev->reshape_position;
memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
@@ -4441,9 +4466,9 @@
print_raid5_conf(conf);
- if (conf->expand_progress != MaxSector) {
+ if (conf->reshape_progress != MaxSector) {
printk("...ok start reshape thread\n");
- conf->expand_lo = conf->expand_progress;
+ conf->reshape_safe = conf->reshape_progress;
atomic_set(&conf->reshape_stripes, 0);
clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
@@ -4782,8 +4807,11 @@
spin_lock_irq(&conf->device_lock);
conf->previous_raid_disks = conf->raid_disks;
conf->raid_disks += mddev->delta_disks;
- conf->expand_progress = 0;
- conf->expand_lo = 0;
+ if (mddev->delta_disks < 0)
+ conf->reshape_progress = raid5_size(mddev, 0, 0);
+ else
+ conf->reshape_progress = 0;
+ conf->reshape_safe = conf->reshape_progress;
spin_unlock_irq(&conf->device_lock);
/* Add some new drives, as many as will fit.
@@ -4825,7 +4853,7 @@
mddev->recovery = 0;
spin_lock_irq(&conf->device_lock);
mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
- conf->expand_progress = MaxSector;
+ conf->reshape_progress = MaxSector;
spin_unlock_irq(&conf->device_lock);
return -EAGAIN;
}
@@ -4842,7 +4870,7 @@
spin_lock_irq(&conf->device_lock);
conf->previous_raid_disks = conf->raid_disks;
- conf->expand_progress = MaxSector;
+ conf->reshape_progress = MaxSector;
spin_unlock_irq(&conf->device_lock);
/* read-ahead size must cover two whole stripes, which is
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index c2f37f2..b2edcc4 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -337,11 +337,16 @@
int raid_disks;
int max_nr_stripes;
- /* 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
- */
+ /* reshape_progress is the leading edge of a 'reshape'
+ * It has value MaxSector when no reshape is happening
+ * If delta_disks < 0, it is the last sector we started work on,
+ * else is it the next sector to work on.
+ */
+ sector_t reshape_progress;
+ /* reshape_safe is the trailing edge of a reshape. We know that
+ * before (or after) this address, all reshape has completed.
+ */
+ sector_t reshape_safe;
int previous_raid_disks;
struct list_head handle_list; /* stripes needing handling */
