Safer debugging and assertion macros.

Spl's debugging and assertion macros macro used the typical do/while(0)
form for if/else friendliness, however, this limits their use in contexts
where a do loop is not valid; such as within another multi-statement
style macro.

The following macros have been converted to not use do/while(0):
	PANIC, ASSERT, ASSERTF, VERIFY, VERIFY3_IMPL

PANIC has been converted to a wrapper around the new spl_PANIC() function.

The other macros have been converted to use the "&&" operator for the
branch-predicition conditional and also to use spl_PANIC().

The __ASSERT() macro was not touched.  It is only used by the debugging
infrastructure and that code, including this macro, will be retired when
the tracepoint patches are merged.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #367
Rate limit debugging stack traces

There have been issues in the past where excessive debug logging
to the console has resulted in significant performance impacts.
In the vast majority of these cases only a few stack traces are
required to diagnose the issue.  Therefore, stack traces dumped to
the console will now we limited to 5 every 60s.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Closes #374
Add functions and macros as used upstream.

Added highbit64() and howmany() which are used in recent upstream
code.  Both highbit() and highbit64() should at some point be
re-factored to use the optimized fls() and fls64() functions.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes #363
Add atomic_swap_32() and atomic_swap_64()

The atomic_swap_32() function maps to atomic_xchg(), and
the atomic_swap_64() function maps to atomic64_xchg().

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #377
Set spl_kmem_cache_reclaim=0 to default

Reinstate the correct default behavior of returning the number of objects
in the cache for reclaim.  This behavior was disabled in recent releases
to do occasional reports of spinning in shrink_slabs().  Those issues have
been resolved and can no longer can be reproduced.  See commit 376dc35.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: DHE <git@dehacked.net>
Issue #358
Closes #379
Set spl_kmem_cache_slab_limit=16384 to default

For small objects the Linux slab allocator should be used to make the most
efficient use of the memory.  However, large objects are not supported by
the Linux slab and therefore the SPL implementation is preferred.  A cutoff
of 16K was determined to be optimal for architectures using 4K pages.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: DHE <git@dehacked.net>
Issue #356
Closes #379
Linux 3.17 compat: remove wait_on_bit action function

Linux kernel 3.17 removes the action function argument from
wait_on_bit().  Add autoconf test and compatibility macro to support
the new interface.

The former "wait_on_bit" interface required an 'action' function to
be provided which does the actual waiting. There were over 20 such
functions in the kernel, many of them identical, though most cases
can be satisfied by one of just two functions: one which uses
io_schedule() and one which just uses schedule().  This API change
was made to consolidate all of those redundant wait functions.

References: torvalds/linux@7431620

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #378
Cleanup vn_rename() and vn_remove()

zfsonlinux/spl#bcb15891ab394e11615eee08bba1fd85ac32e158 implemented
Linux 3.6+ support by adding duplicate vn_rename and vn_remove
functions. The new ones were cleaner, but the duplicate functions made
the codebase less maintainable. This adds some compatibility shims that
allow us to retire the older vn_rename and vn_remove in favor of the new
ones on old kernels. The result is a net 143 line reduction in lines of
code and a cleaner codebase.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #370
Avoid PAGESIZE redefinition

Add #ifndef PAGESIZE to avoid redefinition warning on platforms
where this value is already provided.

Signed-off-by: stf <s@ctrlc.hu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #382