Fix z_sync_cnt decrement in zfs_close

The comment in zfs_close states that "Under Linux the zfs_close() hook
is not symmetric with zfs_open()". This is not true. zfs_open/zfs_close
is associated with every successful struct file creation/deletion, which
should always be balanced.

Here is an example of what's wrong:

Process A		B
	open(O_SYNC)
	z_sync_cnt = 1
			open(O_SYNC)
			z_sync_cnt = 2
	close()
	z_sync_cnt = 0

So z_sync_cnt is 0 even if B still has the file with O_SYNC.

Also moves the generic_file_open call before zfs_open to ensure that in
the case generic_file_open fails z_sync_cnt is not incremented.  This
is safe because generic_file_open has no side effects.

Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1962
Fix grammar in parse_options() error message

A minor grammar error was corrected in in the parse_options()
error handling for the ENOENT case.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: renelson <bnelson@nelsonbe.com>
Issue #1968
Handle acl flags from util-linux mount command

Add acl, noacl and posixacl to option_map, avoiding ENOENT error
case when mount from util-linux-2.24 execs mount.zfs with any of
those flags

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: renelson <bnelson@nelsonbe.com>
Issue #1968
Cause zfs.spec to place dracut files properly

This is an extension of commit ffb2111.  As the fedora conditional
has been added, this allows centos/rhel-6 to fall back to the
proper directory (/usr/share/dracut)

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1984
Add zfs_send_corrupt_data module option

Tuning setting to ignore read/checksum errors when sending data.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1982
Issue #1897
Illumos #4208

4208 Typo in zfs_main.c: "posxiuser"

Reviewed by: Sonu Pillai <sonu.pillai@delphix.com>
Reviewed by: Will Guyette <will.guyette@delphix.com>
Reviewed by: Eric Diven <eric.diven@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  https://www.illumos.org/issues/4208
  illumos/illumos-gate@f38cb554a534c6df738be3f4d23327e69888e634

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1986
cstyle: Exclude several files from 'make checkstyle'

The zfs_config.h header and *.mod.c files are both products
of the build process.  They must be excluded from the style
check because they are not part of the pristine source.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1821
cstyle: Allow spaces in all comments

Update the cstyle.pl script to allow pictures in all comments not
just header comments.  Recent changes from Illumos such as d3cc8b1
have relocated various pictures in the standard block comments to
make the code more readable.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1821
cstyle: Resolve C style issues

The vast majority of these changes are in Linux specific code.
They are the result of not having an automated style checker to
validate the code when it was originally written.  Others were
caused when the common code was slightly adjusted for Linux.

This patch contains no functional changes.  It only refreshes
the code to conform to style guide.

Everyone submitting patches for inclusion upstream should now
run 'make checkstyle' and resolve any warning prior to opening
a pull request.  The automated builders have been updated to
fail a build if when 'make checkstyle' detects an issue.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1821
Add full SELinux support

Four new dataset properties have been added to support SELinux.  They
are 'context', 'fscontext', 'defcontext' and 'rootcontext' which map
directly to the context options described in mount(8).  When one of
these properties is set to something other than 'none'.  That string
will be passed verbatim as a mount option for the given context when
the filesystem is mounted.

For example, if you wanted the rootcontext for a filesystem to be set
to 'system_u:object_r:fs_t' you would set the property as follows:

  $ zfs set rootcontext="system_u:object_r:fs_t" storage-pool/media

This will ensure the filesystem is automatically mounted with that
rootcontext.  It is equivalent to manually specifying the rootcontext
with the -o option like this:

  $ zfs mount -o rootcontext=system_u:object_r:fs_t storage-pool/media

By default all four contexts are set to 'none'.  Further information
on SELinux contexts is detailed in mount(8) and selinux(8) man pages.

Signed-off-by: Matthew Thode <prometheanfire@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Closes #1504