Add I/O Read/Write Accounting

Because ZFS bypasses the page cache we don't inherit per-task I/O
accounting for free.  However, the Linux kernel does provide helper
functions allow us to perform our own accounting.  These are most
commonly used for direct IO which also bypasses the page cache, but
they can be used for the common read/write call paths as well.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #313
Issue #1275
Fixes #1841 : add missing libzfs_core to some Makefiles
Merge branch 'pr-1878' into 0.6.3_turbo
Document ZFS module parameters.
Closes: #1856
Accept user specified spl and kernel source dir.
Merge commit 'turbo/kmod_fixes' into 0.6.3_turbo
Merge commit 'turbo/module_params' into 0.6.3_turbo
Merge branch 'pr-1872' into 0.6.3_turbo
Illumos #4322

4322 ZFS deadlock on dp_config_rwlock
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Ilya Usvyatsky <ilya.usvyatsky@nexenta.com>
Approved by: Dan McDonald <danmcd@nexenta.com>

References:
  https://www.illumos.org/issues/4322
  https://github.com/illumos/illumos-gate/commit/c50d56f667f119d78fa3d94d6bef2c298ba556f6

Ported by: Chris Dunlop <chris@onthe.net.au>
Closes #1886
Merge branch 'pr-1887' into 0.6.3_turbo
Fix typos in commit b83e3e48c9b183a80dd00eb6c7431a1cbc7d89c9

There's a missing semicolon and equals sign in the first hunk of this
commit in config/kernel-bdi.m4. This results in the test always
failing. The effects were noticed when rrdtool, a tool which modifies
files by mmap() and msync(), would have data never get saved to disk
in spite of the files working while the mounted filesystem remains
mounted.

Signed-off-by: DHE <git@dehacked.net>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Closes #1889
Illumos #4322

4322 ZFS deadlock on dp_config_rwlock
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Ilya Usvyatsky <ilya.usvyatsky@nexenta.com>
Approved by: Dan McDonald <danmcd@nexenta.com>

References:
  https://www.illumos.org/issues/4322
  illumos/illumos-gate@c50d56f667f119d78fa3d94d6bef2c298ba556f6

Ported by: Chris Dunlop <chris@onthe.net.au>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1886
Add missing libzfs_core to Makefiles

On some platforms symbols provided by libzfs_core and used by
libzfs were not available to the linker.  To avoid this issue
libzfs_core has been added to the list of required libraries
when building utilities which depend on libzfs.  This should
have been handled properly by libtool and it's still not
entirely clear why it wasn't on all platforms.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1841
Document ZFS module parameters.

This is a first draft of a zfs-module-parameters(5) man page. I have
just extracted the parameter name and its description with modinfo,
then checked the source what type it is and its default value.

This will need more work, preferably someone that actually know these
values and what to use them for.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1856
Add I/O Read/Write Accounting

Because ZFS bypasses the page cache we don't inherit per-task I/O
accounting for free.  However, the Linux kernel does provide helper
functions allow us to perform our own accounting.  These are most
commonly used for direct IO which also bypasses the page cache, but
they can be used for the common read/write call paths as well.

Signed-off-by: Pavel Snajdr <snajpa@snajpa.net>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #313
Closes #1275
Illumos #2583

2583 Add -p (parsable) option to zfs list

References:
  https://www.illumos.org/issues/2583
  illumos/illumos-gate@43d68d68c1ce08fb35026bebfb141af422e7082e

Ported-by: Gregor Kopka <gregor@kopka.net>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes: #937
Change zfs-dkms requirement

Version 2.2.0.3-20 of dkms in the EPEL/Fedora repositories added the
necessary patches to support ZoL,  Therefore, the zfs-dkms requirement
on dkms is set to match that version or higher.  This allows us to
drop the custom dkms build in the ZoL EPEL/Fedora repositories.

References:
  https://bugzilla.redhat.com/show_bug.cgi?id=1023598

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1873
Merge branch 'master' of git://github.com/zfsonlinux/zfs into 0.6.3_turbo
Some more nvlist allocations in hold processing need to use KM_PUSHPAGE.

This should hopefully catch the rest of the allocations in the
user hold/release processing that were missed by commit
65c67ea86e9f112177f1ad32de8e780f10798a64.
Merge branch 'issue-1868' of git://github.com/dweeezil/zfs into 0.6.3_turbo