This allows user-space to access data safely.
This is needed for raid5 reshape as user-space needs to take
a backup of the first few stripes before allowing reshape
to commense.
It will also be useful in cluster-aware raid1 configurations
so that all cluster members can leave a section of the array untouched
while a resync/recovery happens.
A 'start' and 'end' of the suspended range are written to 2 sysfs
attributes. Note that only one range can be suspended at a time.
Signed-off-by: Neil Brown <neilb@xxxxxxx>
### Diffstat output
./drivers/md/md.c | 59 ++++++++++++++++++++++++++++++++++++++++++++
./drivers/md/raid5.c | 14 ++++++++++
./include/linux/raid/md_k.h | 4 ++
3 files changed, 77 insertions(+)
diff ./drivers/md/md.c~current~ ./drivers/md/md.c
--- ./drivers/md/md.c~current~ 2006-03-17 11:48:59.000000000 +1100
+++ ./drivers/md/md.c 2006-03-17 11:48:59.000000000 +1100
@@ -2360,6 +2360,63 @@ sync_completed_show(mddev_t *mddev, char
static struct md_sysfs_entry
md_sync_completed = __ATTR_RO(sync_completed);
+static ssize_t
+suspend_lo_show(mddev_t *mddev, char *page)
+{
+ return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_lo);
+}
+
+static ssize_t
+suspend_lo_store(mddev_t *mddev, const char *buf, size_t len)
+{
+ char *e;
+ unsigned long long new = simple_strtoull(buf, &e, 10);
+
+ if (mddev->pers->quiesce == NULL)
+ return -EINVAL;
+ if (buf == e || (*e && *e != '\n'))
+ return -EINVAL;
+ if (new >= mddev->suspend_hi ||
+ (new > mddev->suspend_lo && new < mddev->suspend_hi)) {
+ mddev->suspend_lo = new;
+ mddev->pers->quiesce(mddev, 2);
+ return len;
+ } else
+ return -EINVAL;
+}
+static struct md_sysfs_entry md_suspend_lo =
+__ATTR(suspend_lo, S_IRUGO|S_IWUSR, suspend_lo_show, suspend_lo_store);
+
+
+static ssize_t
+suspend_hi_show(mddev_t *mddev, char *page)
+{
+ return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_hi);
+}
+
+static ssize_t
+suspend_hi_store(mddev_t *mddev, const char *buf, size_t len)
+{
+ char *e;
+ unsigned long long new = simple_strtoull(buf, &e, 10);
+
+ if (mddev->pers->quiesce == NULL)
+ return -EINVAL;
+ if (buf == e || (*e && *e != '\n'))
+ return -EINVAL;
+ if ((new <= mddev->suspend_lo && mddev->suspend_lo >= mddev->suspend_hi) ||
+ (new > mddev->suspend_lo && new > mddev->suspend_hi)) {
+ mddev->suspend_hi = new;
+ mddev->pers->quiesce(mddev, 1);
+ mddev->pers->quiesce(mddev, 0);
+ return len;
+ } else
+ return -EINVAL;
+}
+static struct md_sysfs_entry md_suspend_hi =
+__ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);
+
+
static struct attribute *md_default_attrs[] = {
&md_level.attr,
&md_raid_disks.attr,
@@ -2377,6 +2434,8 @@ static struct attribute *md_redundancy_a
&md_sync_max.attr,
&md_sync_speed.attr,
&md_sync_completed.attr,
+ &md_suspend_lo.attr,
+ &md_suspend_hi.attr,
NULL,
};
static struct attribute_group md_redundancy_group = {
diff ./drivers/md/raid5.c~current~ ./drivers/md/raid5.c
--- ./drivers/md/raid5.c~current~ 2006-03-17 11:48:59.000000000 +1100
+++ ./drivers/md/raid5.c 2006-03-17 11:48:59.000000000 +1100
@@ -1790,6 +1790,15 @@ static int make_request(request_queue_t
goto retry;
}
}
+ /* FIXME what if we get a false positive because these
+ * are being updated.
+ */
+ if (logical_sector >= mddev->suspend_lo &&
+ logical_sector < mddev->suspend_hi) {
+ release_stripe(sh);
+ schedule();
+ goto retry;
+ }
if (test_bit(STRIPE_EXPANDING, &sh->state) ||
!add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
@@ -2708,6 +2717,10 @@ static void raid5_quiesce(mddev_t *mddev
raid5_conf_t *conf = mddev_to_conf(mddev);
switch(state) {
+ case 2: /* resume for a suspend */
+ wake_up(&conf->wait_for_overlap);
+ break;
+
case 1: /* stop all writes */
spin_lock_irq(&conf->device_lock);
conf->quiesce = 1;
@@ -2721,6 +2734,7 @@ static void raid5_quiesce(mddev_t *mddev
spin_lock_irq(&conf->device_lock);
conf->quiesce = 0;
wake_up(&conf->wait_for_stripe);
+ wake_up(&conf->wait_for_overlap);
spin_unlock_irq(&conf->device_lock);
break;
}
diff ./include/linux/raid/md_k.h~current~ ./include/linux/raid/md_k.h
--- ./include/linux/raid/md_k.h~current~ 2006-03-17 11:48:59.000000000 +1100
+++ ./include/linux/raid/md_k.h 2006-03-17 11:48:59.000000000 +1100
@@ -151,6 +151,10 @@ struct mddev_s
sector_t resync_mismatches; /* count of sectors where
* parity/replica mismatch found
*/
+
+ /* allow user-space to request suspension of IO to regions of the array */
+ sector_t suspend_lo;
+ sector_t suspend_hi;
/* if zero, use the system-wide default */
int sync_speed_min;
int sync_speed_max;
-
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