Allow '-o remount' for non-legacy datasets

This is done for compatibility with existing Linux infrastructure.

In particular, when using zfs as a root filesystem there are init
scripts which as part of shutdown remount root read-only.  Also,
the new systemd infrastructure being used by Fedora expects to be
able to remount a file system read-write.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #847
Adding grub2 mkconfig support patch

Added simply for convenience until this, or an equivilant, change
is merged in the upstream grub2 source.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #847
Illumos #1644, #1645, #1646, #1647, #1708

1644 add ZFS "clones" property
1645 add ZFS "written" and "written@..." properties
1646 "zfs send" should estimate size of stream
1647 "zfs destroy" should determine space reclaimed by
     destroying multiple snapshots
1708 adjust size of zpool history data

References:
  https://www.illumos.org/issues/1644
  https://www.illumos.org/issues/1645
  https://www.illumos.org/issues/1646
  https://www.illumos.org/issues/1647
  https://www.illumos.org/issues/1708

This commit modifies the user to kernel space ioctl ABI.  Extra
care should be taken when updating to ensure both the kernel
modules and utilities are updated.  This change has reordered
all of the new ioctl()s to the end of the list.  This should
help minimize this issue in the future.

Reviewed by: Richard Lowe <richlowe@richlowe.net>
Reviewed by: George Wilson <gwilson@zfsmail.com>
Reviewed by: Albert Lee <trisk@opensolaris.org>
Approved by: Garrett D'Amore <garret@nexenta.com>

Ported by: Martin Matuska <martin@matuska.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #826
Closes #664
Limit the number of blocks to discard at once.

The number of blocks that can be discarded in one BLKDISCARD ioctl on a
zvol is currently unlimited. Some applications, such as mkfs, discard
the whole volume at once and they use the maximum possible discard size
to do that. As a result, several gigabytes discard requests are not
uncommon.

Unfortunately, if a large amount of data is allocated in the zvol, ZFS
can be quite slow to process discard requests. This is especially true
if the volblocksize is low (e.g. the 8K default). As a result, very
large discard requests can take a very long time (seconds to minutes
under heavy load) to complete. This can cause a number of problems, most
notably if the zvol is accessed remotely (e.g. via iSCSI), in which case
the client has a high probability of timing out on the request.

This patch solves the issue by adding a new tunable module parameter:
zvol_max_discard_blocks. This indicates the maximum possible range, in
zvol blocks, of one discard operation. It is set by default to 16384
blocks, which appears to be a good tradeoff. Using the default
volblocksize of 8K this is equivalent to 128 MB. When using the maximum
volblocksize of 128K this is equivalent to 2 GB.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #858
Add missing dependencies to ./copy-builtin

ZFS depends on EFI_PARTITION, ZLIB_DEFLATE and ZLIB_INFLATE, but when
ZFS is integrated with the kernel source tree, menuconfig does not
enforce these dependencies. This can cause build failures in the case of
ZLIB_DEFLATE and ZLIB_INFLATE where symbols are not found. This can also
cause runtime failures in the case of EFI_PARTITION, where the kernel
will not understand GPT partitions when creating pools from raw disks.
We solve this by making menuconfig aware of these dependencies.

Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #854
Set zvol discard_granularity to the volblocksize.

Currently, zvols have a discard granularity set to 0, which suggests to
the upper layer that discard requests of arbirarily small size and
alignment can be made efficiently.

In practice however, ZFS does not handle unaligned discard requests
efficiently: indeed, it is unable to free a part of a block. It will
write zeros to the specified range instead, which is both useless and
inefficient (see dnode_free_range).

With this patch, zvol block devices expose volblocksize as their discard
granularity, so the upper layer is aware that it's not supposed to send
discard requests smaller than volblocksize.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #862
Illumos #1693: persistent 'comment' field for a zpool

Reviewed by: George Wilson <gwilson@zfsmail.com>
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/issues/1693

Ported by: Martin Matuska <martin@matuska.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #678
Add '--with-spl-timeout' option

When checking for the SPL Module.symvers file, a timeout can now be
passed in which will pause the configure step while it waits for this
file to be generated. By default, the configure behavior is unchanged as
a timeout of 0 is used. If a positive number of seconds is passed,
configure will wait that number of seconds for the Module.symvers file
before moving on.

The main motivation for this change was to support parallel execution of
'./configure && make' for the SPL and ZFS packages in preparation of
supporting DKMS based packages.

Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Support building a zfs-modules-dkms sub package

This commit adds support for building a zfs-modules-dkms sub package
built around Dynamic Kernel Module Support. This is to allow building
packages using the DKMS infrastructure which is intended to ease the
burden of kernel version changes, upgrades, etc.

By default zfs-modules-dkms-* sub package will be built as part of
the 'make rpm' target.  Alternately, you can build only the DKMS
module package using the 'make rpm-dkms' target.

Examples:

    # To build packaged binaries as well as a dkms packages
    $ ./configure && make rpm

    # To build only the packaged binary utilities and dkms packages
    $ ./configure && make rpm-utils rpm-dkms

Note: Only the RHEL 5/6, CHAOS 5, and Fedora distributions are
      supported for building the dkms sub package.

Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #535
Export dbuf_* symbols

Export these symbols so they may be used by other ZFS consumers
besides the ZPL.

Remove three stale prototype definites from dbuf.h.  The actual
implementations of these functions were removed/renamed long ago.

It would be good in the long term to remove the existing pragmas
we inherited from Solaris and simply use the dbuf_* names.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Fix man page installation path

RPM versions 4.8 and 4.9 differ in the definition of macro %_mandir:

$ rpm --version ; rpm --showrc | grep ^-14:._mandir
RPM version 4.9.0
-14: _mandir	%{_prefix}/share/man

$ rpm --version ; rpm --showrc | grep ^-14:._mandir
RPM version 4.8.0
-14: _mandir	/usr/share/man

zfs.spec.in defines %_prefix as /, so man pages end up getting
installed in /share/man on RPM 4.9 systems.  To fix this, define
%_mandir relative to %_datadir in the spec file.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #353
Illumos #1888:  zfs(8) should mention zfs recv -e

Reviewed by: Garrett D'Amore <garrett@damore.org>
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
Reviewed by: Gordon Ross <gordon.w.ross@gmail.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/issues/1888

Ported by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #683
Suppress 'zfs_sb_create' memory warning

When mutex debugging is enabled in your kernel the increased
size of the mutex structures can push the zfs_sb_t type beyond
the 8k warning threshold.  This isn't harmful so we suppress
the warning for this case.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #628
Cleanly remove zfs-modules-devel headers

Add the /usr/src/zfs-<version>-<release>/<kernel> directory to
the zfs-modules-devel package.  This ensures that this directory
will be removed when the package is removed.

We do not include the higher level /usr/src/zfs-<version>-<release>
directory since there may be builds for multiple kernels.  Instead,
a %postun rmdir is added which attempts to remove this directory.
It will only succeed when the last zfs-modules-devel-* package
for this specific release is removed.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Export dmu_buf_rele() symbol

While I'd like to remove the various pragmas in module/zfs/dbuf.c.
There are consumers such as Lustre which still depend on dmu_buf_*
versions of the symbols.  Until all consumers can be converted to
use only the dbuf_* names leave this symbol exported.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
ZFS 0.6.0-rc10