dm persistent data: introduce dm_bm_set_read_only
Introduce dm_bm_set_read_only to switch the block manager into a
read-only mode. To be used when dm-thin degrades due to io errors on
the metadata device.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/persistent-data/dm-block-manager.h b/drivers/md/persistent-data/dm-block-manager.h
index 3278855..be5bff6 100644
--- a/drivers/md/persistent-data/dm-block-manager.h
+++ b/drivers/md/persistent-data/dm-block-manager.h
@@ -108,6 +108,19 @@
int dm_bm_flush_and_unlock(struct dm_block_manager *bm,
struct dm_block *superblock);
+/*
+ * Switches the bm to a read only mode. Once read-only mode
+ * has been entered the following functions will return -EPERM.
+ *
+ * dm_bm_write_lock
+ * dm_bm_write_lock_zero
+ * dm_bm_flush_and_unlock
+ *
+ * Additionally you should not use dm_bm_unlock_move, however no error will
+ * be returned if you do.
+ */
+void dm_bm_set_read_only(struct dm_block_manager *bm);
+
u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor);
/*----------------------------------------------------------------*/