This was more or less fixed upstream. Instead of directly accessing
lbolt they now use ddi_get_lbolt() which we can have do the right
thing is the SPL so we don't need to carry this patch.
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.
The extra call to the constructor was there to reinitialize the non-
trivial primatives in the dnode (lists, mutexs, condvars, avl tree, etc).
This was safe, although not exactly clean, on Solaris because none of
the primitives allocate memory. In the Linux port this is not true.
To keep stack usage to a minimum several of the primatives dynamically
allocate memory thus initializing them twice results in a memory leak.
This patch resolves this problem for Solaris and Linux by ensuring all
*_inits are called in the constructor, and all *_destroys are called
in the destructor. Additionally we ensure that all dnode objects are
properly deconstructed before being freed to the slab, and when the
objects are allocated from the slab all required data members are
explicity initialized to correct values.
Brian Behlendorf