md: allow a maximum extent to be set for resyncing
This allows userspace to control resync/reshape progress and synchronise it
with other activities, such as shared access in a SAN, or backing up critical
sections during a tricky reshape.
Writing a number of sectors (which must be a multiple of the chunk size if
such is meaningful) causes a resync to pause when it gets to that point.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/md.txt b/Documentation/md.txt
index 5818628..396cdd9 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -416,6 +416,16 @@
sectors in total that could need to be processed. The two
numbers are separated by a '/' thus effectively showing one
value, a fraction of the process that is complete.
+ A 'select' on this attribute will return when resync completes,
+ when it reaches the current sync_max (below) and possibly at
+ other times.
+
+ sync_max
+ This is a number of sectors at which point a resync/recovery
+ process will pause. When a resync is active, the value can
+ only ever be increased, never decreased. The value of 'max'
+ effectively disables the limit.
+
sync_speed
This shows the current actual speed, in K/sec, of the current
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 00788c5..79eb63f 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -275,6 +275,7 @@
spin_lock_init(&new->write_lock);
init_waitqueue_head(&new->sb_wait);
new->reshape_position = MaxSector;
+ new->resync_max = MaxSector;
new->queue = blk_alloc_queue(GFP_KERNEL);
if (!new->queue) {
@@ -2921,6 +2922,43 @@
static struct md_sysfs_entry md_sync_completed = __ATTR_RO(sync_completed);
static ssize_t
+max_sync_show(mddev_t *mddev, char *page)
+{
+ if (mddev->resync_max == MaxSector)
+ return sprintf(page, "max\n");
+ else
+ return sprintf(page, "%llu\n",
+ (unsigned long long)mddev->resync_max);
+}
+static ssize_t
+max_sync_store(mddev_t *mddev, const char *buf, size_t len)
+{
+ if (strncmp(buf, "max", 3) == 0)
+ mddev->resync_max = MaxSector;
+ else {
+ char *ep;
+ unsigned long long max = simple_strtoull(buf, &ep, 10);
+ if (ep == buf || (*ep != 0 && *ep != '\n'))
+ return -EINVAL;
+ if (max < mddev->resync_max &&
+ test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+ return -EBUSY;
+
+ /* Must be a multiple of chunk_size */
+ if (mddev->chunk_size) {
+ if (max & (sector_t)((mddev->chunk_size>>9)-1))
+ return -EINVAL;
+ }
+ mddev->resync_max = max;
+ }
+ wake_up(&mddev->recovery_wait);
+ return len;
+}
+
+static struct md_sysfs_entry md_max_sync =
+__ATTR(sync_max, S_IRUGO|S_IWUSR, max_sync_show, max_sync_store);
+
+static ssize_t
suspend_lo_show(mddev_t *mddev, char *page)
{
return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_lo);
@@ -3030,6 +3068,7 @@
&md_sync_max.attr,
&md_sync_speed.attr,
&md_sync_completed.attr,
+ &md_max_sync.attr,
&md_suspend_lo.attr,
&md_suspend_hi.attr,
&md_bitmap.attr,
@@ -3579,6 +3618,7 @@
mddev->size = 0;
mddev->raid_disks = 0;
mddev->recovery_cp = 0;
+ mddev->resync_max = MaxSector;
mddev->reshape_position = MaxSector;
mddev->external = 0;
@@ -5443,8 +5483,16 @@
sector_t sectors;
skipped = 0;
+ if (j >= mddev->resync_max) {
+ sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+ wait_event(mddev->recovery_wait,
+ mddev->resync_max > j
+ || kthread_should_stop());
+ }
+ if (kthread_should_stop())
+ goto interrupted;
sectors = mddev->pers->sync_request(mddev, j, &skipped,
- currspeed < speed_min(mddev));
+ currspeed < speed_min(mddev));
if (sectors == 0) {
set_bit(MD_RECOVERY_ERR, &mddev->recovery);
goto out;
@@ -5486,15 +5534,9 @@
}
- if (kthread_should_stop()) {
- /*
- * got a signal, exit.
- */
- printk(KERN_INFO
- "md: md_do_sync() got signal ... exiting\n");
- set_bit(MD_RECOVERY_INTR, &mddev->recovery);
- goto out;
- }
+ if (kthread_should_stop())
+ goto interrupted;
+
/*
* this loop exits only if either when we are slower than
@@ -5558,9 +5600,22 @@
skip:
mddev->curr_resync = 0;
+ mddev->resync_max = MaxSector;
+ sysfs_notify(&mddev->kobj, NULL, "sync_completed");
wake_up(&resync_wait);
set_bit(MD_RECOVERY_DONE, &mddev->recovery);
md_wakeup_thread(mddev->thread);
+ return;
+
+ interrupted:
+ /*
+ * got a signal, exit.
+ */
+ printk(KERN_INFO
+ "md: md_do_sync() got signal ... exiting\n");
+ set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+ goto out;
+
}
EXPORT_SYMBOL_GPL(md_do_sync);
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index e0b8d0dd..ae7c152 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1767,6 +1767,8 @@
return rv;
}
+ if (max_sector > mddev->resync_max)
+ max_sector = mddev->resync_max; /* Don't do IO beyond here */
nr_sectors = 0;
sync_blocks = 0;
do {
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index ba12527..d6f1288 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1657,6 +1657,9 @@
return (max_sector - sector_nr) + sectors_skipped;
}
+ if (max_sector > mddev->resync_max)
+ max_sector = mddev->resync_max; /* Don't do IO beyond here */
+
/* make sure whole request will fit in a chunk - if chunks
* are meaningful
*/
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 388a974..e946de6 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3698,6 +3698,25 @@
release_stripe(sh);
first_sector += STRIPE_SECTORS;
}
+ /* If this takes us to the resync_max point where we have to pause,
+ * then we need to write out the superblock.
+ */
+ sector_nr += conf->chunk_size>>9;
+ if (sector_nr >= mddev->resync_max) {
+ /* 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;
+ 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;
+ spin_unlock_irq(&conf->device_lock);
+ wake_up(&conf->wait_for_overlap);
+ }
return conf->chunk_size>>9;
}
@@ -3734,6 +3753,12 @@
if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
return reshape_request(mddev, sector_nr, skipped);
+ /* No need to check resync_max as we never do more than one
+ * stripe, and as resync_max will always be on a chunk boundary,
+ * if the check in md_do_sync didn't fire, there is no chance
+ * of overstepping resync_max here
+ */
+
/* if there is too many failed drives and we are trying
* to resync, then assert that we are finished, because there is
* nothing we can do.
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index b579cc6..c77dca3 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -219,6 +219,8 @@
atomic_t recovery_active; /* blocks scheduled, but not written */
wait_queue_head_t recovery_wait;
sector_t recovery_cp;
+ sector_t resync_max; /* resync should pause
+ * when it gets here */
spinlock_t write_lock;
wait_queue_head_t sb_wait; /* for waiting on superblock updates */