Clean patches that merge together various fixes in the thin-dev tree.
Joe Thornber (11):
Unlock the superblock on an error path for new metadata dev creation.
Remove redundant arg from value_ptr()
[dm-thin] [bio prison] Don't use the bi_next field for the holder of
[dm-thin] dm_thin_remove_block() wasn't decrementing the
[dm-thin] btree-remove - fix rebalancing of 3 nodes.
Remove entries from the ref_count tree if they're no longer needed.
[dm-thin] Commit every second to prevent too much of a position
[dm-thin] Add support for external origins.
[dm-thin] Discard support part 1
[dm-thin] Add support for REQ_DISCARD
[dm-thin] some tidy ups of the __open_device() error path (Mike