Recent builds against 2.6.31 flagged dmu_recv_stream() as stack heavy.
As a quick simple way to resolve this I'm preventing the inlining of
certain functions which gcc will inline here because this is the only
place they are called. Futher analysis of this function should be
performed to futher reduce its stack usage.
The 2.6.30 kernel build systems sets -Wframe-larger-than=2048 which causes
a warning to be generated when an individual stack frame exceeds 2048.
This caught the spa_history_log() and dmu_objset_snapshot() functions
which declared a data structure on the stack which contained a char
array of MAXPATHLEN. This in defined to be 4096 in the linux kernel
and I imagine it is quite large under Solaris as well. Regardless, the
offending data structures were moved to the heap to correctly keep the
stack depth to a minimum. We might consider setting this value even
lower to catch additional offenders because we are expecting deep stacks.
Brian Behlendorf