xfs: call xlog_state_release_iclog with l_icloglock held

xfs: call xlog_state_release_iclog with l_icloglock held

All but one caller of xlog_state_release_iclog hold l_icloglock and need
to drop and reacquire it to call xlog_state_release_iclog.  Switch the
xlog_state_release_iclog calling conventions to expect the lock to be
held, and open code the logic (using a shared helper) in the only
remaining caller that does not have the lock (and where not holding it
is a nice performance optimization).  Also move the refactored code to
require the least amount of forward declarations.

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
[darrick: minor whitespace cleanup]
Signed-off-by: Darrick J. Wong <[email protected]>
Reviewed-by: Brian Foster <[email protected]>