md: support bitmap offset appropriate for external-metadata arrays.
For md arrays were metadata is managed externally, the kernel does not
know about a superblock so the superblock offset is 0.
If we want to have a write-intent-bitmap near the end of the
devices of such an array, we should support sector_t sized offset.
We need offset be possibly negative for when the bitmap is before
the metadata, so use loff_t instead.
Also add sanity check that bitmap does not overlap with data.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 4b07e0a..df69295 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -282,11 +282,13 @@
struct bitmap *bitmap; /* the bitmap for the device */
struct {
struct file *file; /* the bitmap file */
- long offset; /* offset from superblock of
+ loff_t offset; /* offset from superblock of
* start of bitmap. May be
* negative, but not '0'
+ * For external metadata, offset
+ * from start of device.
*/
- long default_offset; /* this is the offset to use when
+ loff_t default_offset; /* this is the offset to use when
* hot-adding a bitmap. It should
* eventually be settable by sysfs.
*/