Modify gethrestime to use current_kernel_time()

This allows us to get nanosecond resolution. It also means
we use the same time source as utimensat(now) etc.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #255
Return -1 for generic kmem cache shrinker

It has been observed that it's possible to get in a state where
shrink_slabs() will spin repeated invoking the generic kmem cache
shrinker.  It fails to detect it's not making forward progress
reclaiming from the cache and doesn't give up.  To ensure this
never occurs we unconditionally return -1 after reclaiming what
we can.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Closes zfsonlinux/zfs#1276
Closes zfsonlinux/zfs#1598
Closes zfsonlinux/zfs#1432
Fix KMC_OFFSLAB type caches

Because spl_slab_size() was always returning -ENOSPC for caches of
type KMC_OFFSLAB the cache could never be created.  Additionally
the slab size is rounded up to a page which is what kv_alloc()
expects.  The kv_alloc() code will minimally allocate a page,
in the KMC_OFFSLAB case this could be reduced.

The basic regression tests kmem:slab_small, kmem:slab_large,
and kmem:slab_align regression were updated to test KMC_OFFSLAB.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ying Zhu <casualfisher@gmail.com>
Closes #266
Add kmod repo integration

When the kmod packaging infrastructure was originally added the
dependency on the rpmfusion yum repositories was disabled.  This
was done at the time in favour of getting local builds working.

Now the time has come to conditionally re-enable that functionality
so we can properly provide binary kmod packages.

  ./configure --with-config=srpm
  make SRPM_DEFINE_KMOD='--define="repo rpmfusion"' srpm-kmod
  mock rebuild spl-kmod-x.y.z-r.el6.src.rpm

One nice benefit of finishing this work is that the generic and
fedora spl-kmod spec files can be merged again.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Linux 3.11 compat: Replace num_physpages with totalram_pages

num_physpages was removed by
torvalds/linux@cfa11e08ed39eb28a9eff9a907b20913020c69b5, so lets replace
it with totalram_pages.

This is a bug fix as much as it is a compatibility fix because
num_physpages did not reflect the number of pages actually available to
the kernel:

http://lkml.indiana.edu/hypermail/linux/kernel/0908.2/01001.html

Also, there are known issues with memory calculations when ZFS is in a
Xen dom0. There is a chance that using totalram_pages could resolve
them. This conjecture is untested at the time of writing.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #273
Fix race in spl_kmem_cache_reap_now()

The current code contains a race condition that triggers when bit 2 in
spl.spl_kmem_cache_expire is set, spl_kmem_cache_reap_now() is invoked
and another thread is concurrently accessing its magazine.

spl_kmem_cache_reap_now() currently invokes spl_cache_flush() on each
magazine in the same thread when bit 2 in spl.spl_kmem_cache_expire is
set. This is unsafe because there is one magazine per CPU and the
magazines are lockless, so it is impossible to guarentee that another
CPU is not using its magazine when this function is called.

The solution is to only touch the local CPU's magazine and leave other
CPU's magazines to other CPUs.

Reported-by: DHE
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #274
PaX/GrSecurity Linux 3.8.y compat: Use __no_const on struct ctl_table

The PaX team started constifying `struct ctl_table` as of their Linux
3.8.0 patchset. This lead to zfsonlinux/spl#225 and Gentoo bug #463012.

While investigating our options, I learned that there is a preprocessor
directive called CONSTIFY_PLUGIN that we can use to detect the presence
of the PaX changes and adjust the code accordingly.

The PaX Team had suggested adopting ctl_table_no_const, but supporting
older kernels required declaring that whenever the CONSTIFY_PLUGIN was
set. Future compiler changes could potentially cause that to break in
the presence of -Werror, so instead we define our own spl_ctl_table
typdef and use that. This should be compatible with all PaX kernels.

This introduces a Linux kernel version number check to prevent a build
failure on versions of the PaX GCC plugin that existed for kernels
before Linux 3.8.0. Affected versions of the PaX plugin will trigger a
compiler error when they see no_const cast on a non-constified
structure.  Ordinarily, we would need an autotools check to catch that.
However, it is safe to do a kernel version check instead of an autotools
check in this specific instance because the affected versions of the PaX
GCC plugin only exist for Linux kernels before 3.8.0 and the
constification of `struct ctl_table` by the PaX developers only occurs
in Linux 3.8.0 and later.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #225
Linux 3.8 compat: Use kuid_t/kgid_t when required

When CONFIG_UIDGID_STRICT_TYPE_CHECKS is enabled uid_t/git_t are
replaced by kuid_t/kgid_t, which are structures instead of integral
types. This causes any code that uses an integral type to fail to build.
The User Namespace functionality introduced in Linux 3.8 requires
CONFIG_UIDGID_STRICT_TYPE_CHECKS, so we could not build against any
kernel that supported it.

We resolve this by converting between the new kuid_t/kgid_t structures
and the original uid_t/gid_t types.

Original-patch-by: DHE
Rewrite-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #260
Tag spl-0.6.2

META file and release log updated.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Replace current_kernel_time() with getnstimeofday()

current_kernel_time() is used by the SPLAT, but it is not meant for
performance measurement. We modify the SPLAT to use getnstimeofday(),
which is equivalent to the gethrestime() function on Solaris.
Additionally, we update gethrestime() to invoke getnstimeofday().

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #279
Add kpreempt() compatibility macro

This is needed for the Illumos #4045 write throttle patch.  It is used
in the arc eviction code to avoid blocking all arc activity by sitting on
arcs_mtx too long.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #286
Document how to run SPLAT

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #294
Consistently use local_irq_disable/local_irq_enable

It was observed that spl_kmem_cache_alloc() uses local_irq_save()
and saves the interrupt state in a local variable.  This would
normally be fine except that spl_kmem_cache_alloc() calls
spl_cache_refill() which re-enables interrupts.  It is then
possible that while interrupts are enabled the process is
rescheduled to a different cpu before being disable again.
This could result in us restoring the saved interrupt state
from one cpu to another.

What the consequences of this are aren't perfectly clear, but
this is clearly a bug and it has the potential to cause issues.
The code has been updated to just use local_irq_enable() and
local_irq_disable() to avoid this.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Define SET_ERROR()

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Add callbacks for displaying KSTAT_TYPE_RAW kstats

The current implementation for displaying kstats of type KSTAT_TYPE_RAW
is rather crude. This patch attempts to enhance this handling by
allowing a kstat user to register formatting callbacks which can
optionally be used.

The callbacks allow the user to implement functions for interpreting
their data and transposing it into a character buffer. This buffer,
containing a string representation of the raw data, is then be displayed
through the current /proc textual interface.

Additionally the kstats are made writable because it's now possible
to provide a useful handler via the existing ks_update() interface.

Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #296
Add wrappers for accessing PID and command info

This change adds simple wrappers for accessing a thread's PID and
command character string.

Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #296
Revert "Add KSTAT_TYPE_TXG type"

This reverts commit dba79fcbf2cc50be5caef84ae01657e884ac5d89 in
favor of using the generic KSTAT_TYPE_RAW callbacks.  The advantage
of this approach is that arbitrary types can be added without the
need to add them to the SPL.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #296
Kstat to use private lock by default

While porting Illumos #3537 I found that ks_lock member of kstat_t
structure is different between Illumos and SPL. It is a pointer to
the kmutex_t in Illumos, but the mutex lock itself in SPL.
Apparently Illumos kstat API allows consumer to override the lock
if required. With SPL implementation it is not possible anymore.

Things were alright until the first attempt to actually override
the lock. Porting of Illumos #3537 introduced such code for the
first time.

In order to provide the Solaris/Illumos like functionality we:
  1. convert ks_lock to "kmutex_t *ks_lock"
  2. create a new field "kmutex_t ks_private_lock"
  3. On kstat_create() ks_lock = &ks_private_lock

Thus if consumer doesn't care we still have our internal lock in use.
If, however, consumer does care she has a chance to set ks_lock to
anything else before calling kstat_install().

The rest of the code will use ks_lock regardless of its origin.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #286
3537 add kstat_waitq_enter and friends

These kstat interfaces are required to port
"Illumos #3537 want pool io kstats" to ZFS on Linux.

kstat_waitq_enter()
kstat_waitq_exit()
kstat_runq_enter()
kstat_runq_exit()

Additionally, zero out the ks_data buffer in __kstat_create() so
that the kstat_io_t counters are initialized to zero.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Merge branch 'kstat'

This branch updates the existing kstat infrastructure to be
more flexible.  In particular, it extends the KSTAT_TYPE_RAW
type so it may be used to generate more dynamic kstats without
the need for additional custom types.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>