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-rw-r--r--drivers/md/raid5.c34
-rw-r--r--drivers/md/raid5.h2
2 files changed, 30 insertions, 6 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index bb4b12e370d..3bbc6d64704 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3766,7 +3766,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
int new_data_disks = conf->raid_disks - conf->max_degraded;
int i;
int dd_idx;
- sector_t writepos, safepos, gap;
+ sector_t writepos, readpos, safepos;
sector_t stripe_addr;
int reshape_sectors;
struct list_head stripes;
@@ -3806,26 +3806,46 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
*/
writepos = conf->reshape_progress;
sector_div(writepos, new_data_disks);
+ readpos = conf->reshape_progress;
+ sector_div(readpos, data_disks);
safepos = conf->reshape_safe;
sector_div(safepos, data_disks);
if (mddev->delta_disks < 0) {
writepos -= reshape_sectors;
+ readpos += reshape_sectors;
safepos += reshape_sectors;
- gap = conf->reshape_safe - conf->reshape_progress;
} else {
writepos += reshape_sectors;
+ readpos -= reshape_sectors;
safepos -= reshape_sectors;
- gap = conf->reshape_progress - conf->reshape_safe;
}
+ /* 'writepos' is the most advanced device address we might write.
+ * 'readpos' is the least advanced device address we might read.
+ * 'safepos' is the least address recorded in the metadata as having
+ * been reshaped.
+ * If 'readpos' is behind 'writepos', then there is no way that we can
+ * ensure safety in the face of a crash - that must be done by userspace
+ * making a backup of the data. So in that case there is no particular
+ * rush to update metadata.
+ * Otherwise if 'safepos' is behind 'writepos', then we really need to
+ * update the metadata to advance 'safepos' to match 'readpos' so that
+ * we can be safe in the event of a crash.
+ * So we insist on updating metadata if safepos is behind writepos and
+ * readpos is beyond writepos.
+ * In any case, update the metadata every 10 seconds.
+ * Maybe that number should be configurable, but I'm not sure it is
+ * worth it.... maybe it could be a multiple of safemode_delay???
+ */
if ((mddev->delta_disks < 0
- ? writepos < safepos
- : writepos > safepos) ||
- gap > (new_data_disks)*3000*2 /*3Meg*/) {
+ ? (safepos > writepos && readpos < writepos)
+ : (safepos < writepos && readpos > writepos)) ||
+ time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
/* Cannot proceed until we've updated the superblock... */
wait_event(conf->wait_for_overlap,
atomic_read(&conf->reshape_stripes)==0);
mddev->reshape_position = conf->reshape_progress;
+ conf->reshape_checkpoint = jiffies;
set_bit(MD_CHANGE_DEVS, &mddev->flags);
md_wakeup_thread(mddev->thread);
wait_event(mddev->sb_wait, mddev->flags == 0 ||
@@ -3923,6 +3943,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
wait_event(conf->wait_for_overlap,
atomic_read(&conf->reshape_stripes) == 0);
mddev->reshape_position = conf->reshape_progress;
+ conf->reshape_checkpoint = jiffies;
set_bit(MD_CHANGE_DEVS, &mddev->flags);
md_wakeup_thread(mddev->thread);
wait_event(mddev->sb_wait,
@@ -4957,6 +4978,7 @@ static int raid5_start_reshape(mddev_t *mddev)
spin_unlock_irq(&conf->device_lock);
return -EAGAIN;
}
+ conf->reshape_checkpoint = jiffies;
md_wakeup_thread(mddev->sync_thread);
md_new_event(mddev);
return 0;
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index cdd04568172..52ba99954de 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -352,6 +352,8 @@ struct raid5_private_data {
int previous_raid_disks;
int prev_chunk, prev_algo;
short generation; /* increments with every reshape */
+ unsigned long reshape_checkpoint; /* Time we last updated
+ * metadata */
struct list_head handle_list; /* stripes needing handling */
struct list_head hold_list; /* preread ready stripes */