---

yaml
---
r: 16569
b: refs/heads/master
c: 93c8cad
h: refs/heads/master
i:
  16567: b513f71
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 014236d2b8ec6faea2a6134ab8e019d84d67b524
+refs/heads/master: 93c8cad03f02dbd1532a5413bdced25f000d5728

trunk/Documentation/md.txt

@@ -244,6 +244,12 @@ Each directory contains:
 	it currently fills.  This can only be set while assembling an
 	array.  A device for which this is set is assumed to be working.
 
+      offset
+        This gives the location in the device (in sectors from the
+        start) where data from the array will be stored.  Any part of
+        the device before this offset us not touched, unless it is
+        used for storing metadata (Formats 1.1 and 1.2).
+
 
 An active md device will also contain and entry for each active device
 in the array.  These are named

trunk/drivers/md/md.c

@@ -1664,11 +1664,34 @@ slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
 static struct rdev_sysfs_entry rdev_slot =
 __ATTR(slot, 0644, slot_show, slot_store);
 
+static ssize_t
+offset_show(mdk_rdev_t *rdev, char *page)
+{
+	return sprintf(page, "%llu\n", rdev->data_offset);
+}
+
+static ssize_t
+offset_store(mdk_rdev_t *rdev, const char *buf, size_t len)
+{
+	char *e;
+	unsigned long long offset = simple_strtoull(buf, &e, 10);
+	if (e==buf || (*e && *e != '\n'))
+		return -EINVAL;
+	if (rdev->mddev->pers)
+		return -EBUSY;
+	rdev->data_offset = offset;
+	return len;
+}
+
+static struct rdev_sysfs_entry rdev_offset =
+__ATTR(offset, 0644, offset_show, offset_store);
+
 static struct attribute *rdev_default_attrs[] = {
 	&rdev_state.attr,
 	&rdev_super.attr,
 	&rdev_errors.attr,
 	&rdev_slot.attr,
+	&rdev_offset.attr,
 	NULL,
 };
 static ssize_t