btrfs: fix zero size inode with non-zero size after log replay

btrfs: don't BUG() on unexpected delayed ref type in runonedelayedref()

In the Linux kernel, the following vulnerability has been resolved:

btrfs: add missing RCU unlock in error path in tryreleasesubpageextentbuffer()

Call rcureadlock() before exiting the loop in tryreleasesubpageextentbuffer() because there is a rcureadunlock() call past the loop.

This has been detected by the Clang thread-safety analyzer.