drbd: Allow online resizing of DRBD devices while peer not reachable (needs to be explicitly forced)

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_int.h

@@ -1371,10 +1371,9 @@ extern int is_valid_ar_handle(struct drbd_request *, sector_t);
 extern void drbd_suspend_io(struct drbd_conf *mdev);
 extern void drbd_resume_io(struct drbd_conf *mdev);
 extern char *ppsize(char *buf, unsigned long long size);
-extern sector_t drbd_new_dev_size(struct drbd_conf *,
-		struct drbd_backing_dev *);
+extern sector_t drbd_new_dev_size(struct drbd_conf *, struct drbd_backing_dev *, int);
 enum determine_dev_size { dev_size_error = -1, unchanged = 0, shrunk = 1, grew = 2 };
-extern enum determine_dev_size drbd_determin_dev_size(struct drbd_conf *) __must_hold(local);
+extern enum determine_dev_size drbd_determin_dev_size(struct drbd_conf *, int force) __must_hold(local);
 extern void resync_after_online_grow(struct drbd_conf *);
 extern void drbd_setup_queue_param(struct drbd_conf *mdev, unsigned int) __must_hold(local);
 extern int drbd_set_role(struct drbd_conf *mdev, enum drbd_role new_role,

drivers/block/drbd/drbd_nl.c

@@ -510,7 +510,7 @@ void drbd_resume_io(struct drbd_conf *mdev)
  * Returns 0 on success, negative return values indicate errors.
  * You should call drbd_md_sync() after calling this function.
  */
-enum determine_dev_size drbd_determin_dev_size(struct drbd_conf *mdev) __must_hold(local)
+enum determine_dev_size drbd_determin_dev_size(struct drbd_conf *mdev, int force) __must_hold(local)
 {
 	sector_t prev_first_sect, prev_size; /* previous meta location */
 	sector_t la_size;
@@ -541,7 +541,7 @@ enum determine_dev_size drbd_determin_dev_size(struct drbd_conf *mdev) __must_ho
 	/* TODO: should only be some assert here, not (re)init... */
 	drbd_md_set_sector_offsets(mdev, mdev->ldev);
 
-	size = drbd_new_dev_size(mdev, mdev->ldev);
+	size = drbd_new_dev_size(mdev, mdev->ldev, force);
 
 	if (drbd_get_capacity(mdev->this_bdev) != size ||
 	    drbd_bm_capacity(mdev) != size) {
@@ -596,7 +596,7 @@ out:
 }
 
 sector_t
-drbd_new_dev_size(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
+drbd_new_dev_size(struct drbd_conf *mdev, struct drbd_backing_dev *bdev, int assume_peer_has_space)
 {
 	sector_t p_size = mdev->p_size;   /* partner's disk size. */
 	sector_t la_size = bdev->md.la_size_sect; /* last agreed size. */
@@ -606,6 +606,11 @@ drbd_new_dev_size(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
 
 	m_size = drbd_get_max_capacity(bdev);
 
+	if (mdev->state.conn < C_CONNECTED && assume_peer_has_space) {
+		dev_warn(DEV, "Resize while not connected was forced by the user!\n");
+		p_size = m_size;
+	}
+
 	if (p_size && m_size) {
 		size = min_t(sector_t, p_size, m_size);
 	} else {
@@ -965,7 +970,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 
 	/* Prevent shrinking of consistent devices ! */
 	if (drbd_md_test_flag(nbc, MDF_CONSISTENT) &&
-	   drbd_new_dev_size(mdev, nbc) < nbc->md.la_size_sect) {
+	    drbd_new_dev_size(mdev, nbc, 0) < nbc->md.la_size_sect) {
 		dev_warn(DEV, "refusing to truncate a consistent device\n");
 		retcode = ERR_DISK_TO_SMALL;
 		goto force_diskless_dec;
@@ -1052,7 +1057,7 @@ static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 	    !drbd_md_test_flag(mdev->ldev, MDF_CONNECTED_IND))
 		set_bit(USE_DEGR_WFC_T, &mdev->flags);
 
-	dd = drbd_determin_dev_size(mdev);
+	dd = drbd_determin_dev_size(mdev, 0);
 	if (dd == dev_size_error) {
 		retcode = ERR_NOMEM_BITMAP;
 		goto force_diskless_dec;
@@ -1504,7 +1509,7 @@ static int drbd_nl_resize(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
 	}
 
 	mdev->ldev->dc.disk_size = (sector_t)rs.resize_size;
-	dd = drbd_determin_dev_size(mdev);
+	dd = drbd_determin_dev_size(mdev, rs.resize_force);
 	drbd_md_sync(mdev);
 	put_ldev(mdev);
 	if (dd == dev_size_error) {

drivers/block/drbd/drbd_receiver.c

@@ -2870,7 +2870,7 @@ static int receive_sizes(struct drbd_conf *mdev, struct p_header *h)
 
 		/* Never shrink a device with usable data during connect.
 		   But allow online shrinking if we are connected. */
-		if (drbd_new_dev_size(mdev, mdev->ldev) <
+		if (drbd_new_dev_size(mdev, mdev->ldev, 0) <
 		   drbd_get_capacity(mdev->this_bdev) &&
 		   mdev->state.disk >= D_OUTDATED &&
 		   mdev->state.conn < C_CONNECTED) {
@@ -2885,7 +2885,7 @@ static int receive_sizes(struct drbd_conf *mdev, struct p_header *h)
 #undef min_not_zero
 
 	if (get_ldev(mdev)) {
-		dd = drbd_determin_dev_size(mdev);
+	  dd = drbd_determin_dev_size(mdev, 0);
 		put_ldev(mdev);
 		if (dd == dev_size_error)
 			return FALSE;

include/linux/drbd_nl.h

@@ -69,6 +69,7 @@ NL_PACKET(disconnect, 6, )
 
 NL_PACKET(resize, 7,
 	NL_INT64(		29,	T_MAY_IGNORE,	resize_size)
+	NL_BIT(			68,	T_MAY_IGNORE,	resize_force)
 )
 
 NL_PACKET(syncer_conf, 8,