tree 433fad6b6d2b64b8ce3f97f759347097b851e6b4
parent 9345457f4a539a40056431aeb6f068750857472f
author Jan Schmidt <list.btrfs@jan-o-sch.net> 1340269153 +0200
committer Jan Schmidt <list.btrfs@jan-o-sch.net> 1340807678 +0200

Btrfs: fix tree mod log for root replacements at leaf level

For the tree mod log, we don't log any operations at leaf level. If the root
is at the leaf level (i.e. the tree consists only of the root), then
__tree_mod_log_oldest_root will find a ROOT_REPLACE operation in the log
(because we always log that one no matter which level), but no other
operations.

With this patch __tree_mod_log_oldest_root exits cleanly instead of
BUGging in this situation. get_old_root checks if its really a root at leaf
level in case we don't have any operations and WARNs if this assumption
breaks.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>