aboutsummaryrefslogtreecommitdiff
path: root/drivers/block/drbd/drbd_nl.c
diff options
context:
space:
mode:
authorLars Ellenberg <lars.ellenberg@linbit.com>2013-03-19 18:16:43 +0100
committerJens Axboe <axboe@kernel.dk>2013-03-22 18:13:59 -0600
commitae8bf312e97d554b6aa32e7b2ceb993812ad0835 (patch)
tree7ed6d4fcf6385c1dbc694cf4f43f884436ae104a /drivers/block/drbd/drbd_nl.c
parent9114d79569a3fb858a7ecb1f21cb1dec93dc2f21 (diff)
downloadvexpress-lsk-ae8bf312e97d554b6aa32e7b2ceb993812ad0835.tar.gz
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>
Diffstat (limited to 'drivers/block/drbd/drbd_nl.c')
-rw-r--r--drivers/block/drbd/drbd_nl.c42
1 files changed, 31 insertions, 11 deletions
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 2af26fc9528..581f6800cc3 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -696,12 +696,32 @@ out:
return 0;
}
-/* initializes the md.*_offset members, so we are able to find
- * the on disk meta data */
+/* Initializes the md.*_offset members, so we are able to find
+ * the on disk meta data.
+ *
+ * We currently have two possible layouts:
+ * external:
+ * |----------- md_size_sect ------------------|
+ * [ 4k superblock ][ activity log ][ Bitmap ]
+ * | al_offset == 8 |
+ * | bm_offset = al_offset + X |
+ * ==> bitmap sectors = md_size_sect - bm_offset
+ *
+ * internal:
+ * |----------- md_size_sect ------------------|
+ * [data.....][ Bitmap ][ activity log ][ 4k superblock ]
+ * | al_offset < 0 |
+ * | bm_offset = al_offset - Y |
+ * ==> bitmap sectors = Y = al_offset - bm_offset
+ *
+ * Activity log size used to be fixed 32kB,
+ * but is about to become configurable.
+ */
static void drbd_md_set_sector_offsets(struct drbd_conf *mdev,
struct drbd_backing_dev *bdev)
{
sector_t md_size_sect = 0;
+ unsigned int al_size_sect = MD_32kB_SECT;
int meta_dev_idx;
rcu_read_lock();
@@ -710,23 +730,23 @@ static void drbd_md_set_sector_offsets(struct drbd_conf *mdev,
switch (meta_dev_idx) {
default:
/* v07 style fixed size indexed meta data */
- bdev->md.md_size_sect = MD_RESERVED_SECT;
+ bdev->md.md_size_sect = MD_128MB_SECT;
bdev->md.md_offset = drbd_md_ss__(mdev, bdev);
- bdev->md.al_offset = MD_AL_OFFSET;
- bdev->md.bm_offset = MD_BM_OFFSET;
+ bdev->md.al_offset = MD_4kB_SECT;
+ bdev->md.bm_offset = MD_4kB_SECT + al_size_sect;
break;
case DRBD_MD_INDEX_FLEX_EXT:
/* just occupy the full device; unit: sectors */
bdev->md.md_size_sect = drbd_get_capacity(bdev->md_bdev);
bdev->md.md_offset = 0;
- bdev->md.al_offset = MD_AL_OFFSET;
- bdev->md.bm_offset = MD_BM_OFFSET;
+ bdev->md.al_offset = MD_4kB_SECT;
+ bdev->md.bm_offset = MD_4kB_SECT + al_size_sect;
break;
case DRBD_MD_INDEX_INTERNAL:
case DRBD_MD_INDEX_FLEX_INT:
bdev->md.md_offset = drbd_md_ss__(mdev, bdev);
/* al size is still fixed */
- bdev->md.al_offset = -MD_AL_SECTORS;
+ bdev->md.al_offset = -al_size_sect;
/* we need (slightly less than) ~ this much bitmap sectors: */
md_size_sect = drbd_get_capacity(bdev->backing_bdev);
md_size_sect = ALIGN(md_size_sect, BM_SECT_PER_EXT);
@@ -735,11 +755,11 @@ static void drbd_md_set_sector_offsets(struct drbd_conf *mdev,
/* plus the "drbd meta data super block",
* and the activity log; */
- md_size_sect += MD_BM_OFFSET;
+ md_size_sect += MD_4kB_SECT + al_size_sect;
bdev->md.md_size_sect = md_size_sect;
/* bitmap offset is adjusted by 'super' block size */
- bdev->md.bm_offset = -md_size_sect + MD_AL_OFFSET;
+ bdev->md.bm_offset = -md_size_sect + MD_4kB_SECT;
break;
}
rcu_read_unlock();
@@ -1416,7 +1436,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
min_md_device_sectors = (2<<10);
} else {
max_possible_sectors = DRBD_MAX_SECTORS;
- min_md_device_sectors = MD_RESERVED_SECT * (new_disk_conf->meta_dev_idx + 1);
+ min_md_device_sectors = MD_128MB_SECT * (new_disk_conf->meta_dev_idx + 1);
}
if (drbd_get_capacity(nbc->md_bdev) < min_md_device_sectors) {