drbd: cleanup ondisk meta data layout calculations and defines
Add a comment about our meta data layout variants,
and rename a few defines (e.g. MD_RESERVED_SECT -> MD_128MB_SECT)
to make it clear that they are short hand for fixed constants,
and not arbitrarily to be redefined as one may see fit.
Properly pad struct meta_data_on_disk to 4kB,
and initialize to zero not only the first 512 Byte,
but all of it in drbd_md_sync().
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
index 8dc2950..64fbb83 100644
--- a/drivers/block/drbd/drbd_bitmap.c
+++ b/drivers/block/drbd/drbd_bitmap.c
@@ -612,6 +612,17 @@
}
}
+/* For the layout, see comment above drbd_md_set_sector_offsets(). */
+static u64 drbd_md_on_disk_bits(struct drbd_backing_dev *ldev)
+{
+ u64 bitmap_sectors;
+ if (ldev->md.al_offset == 8)
+ bitmap_sectors = ldev->md.md_size_sect - ldev->md.bm_offset;
+ else
+ bitmap_sectors = ldev->md.al_offset - ldev->md.bm_offset;
+ return bitmap_sectors << (9 + 3);
+}
+
/*
* make sure the bitmap has enough room for the attached storage,
* if necessary, resize.
@@ -668,7 +679,7 @@
words = ALIGN(bits, 64) >> LN2_BPL;
if (get_ldev(mdev)) {
- u64 bits_on_disk = ((u64)mdev->ldev->md.md_size_sect-MD_BM_OFFSET) << 12;
+ u64 bits_on_disk = drbd_md_on_disk_bits(mdev->ldev);
put_ldev(mdev);
if (bits > bits_on_disk) {
dev_info(DEV, "bits = %lu\n", bits);