Remove ZFC_IOC_*_MINOR ioctl()s

Early versions of ZFS coordinated the creation and destruction
of device minors from userspace.  This was inherently racy and
in late 2009 these ioctl()s were removed leaving everything up
to the kernel.  This significantly simplified the code.

However, we never picked up these changes in ZoL since we'd
already significantly adjusted this code for Linux.  This patch
aims to rectify that by finally removing ZFC_IOC_*_MINOR ioctl()s
and moving all the functionality down in to the kernel.  Since
this cleanup will change the kernel/user ABI it's being done
in the same tag as the previous libzfs_core ABI changes.  This
will minimize, but not eliminate, the disruption to end users.

Once merged ZoL, Illumos, and FreeBSD will basically be back
in sync in regards to handling ZVOLs in the common code.  While
each platform must have its own custom zvol.c implemenation the
interfaces provided are consistent.

NOTES:

1) This patch introduces one subtle change in behavior which
   could not be easily avoided.  Prior to this change callers
   of 'zfs create -V ...' were guaranteed that upon exit the
   /dev/zvol/ block device link would be created or an error
   returned.  That's no longer the case.  The utilities will no
   longer block waiting for the symlink to be created.  Callers
   are now responsible for blocking, this is why a 'udev_wait'
   call was added to the 'label' function in scripts/common.sh.

2) The read-only behavior of a ZVOL now solely depends on if
   the ZVOL_RDONLY bit is set in zv->zv_flags.  The redundant
   policy setting in the gendisk structure was removed.  This
   both simplifies the code and allows us to safely leverage
   set_disk_ro() to issue a KOBJ_CHANGE uevent.  See the
   comment in the code for futher details on this.

3) Because __zvol_create_minor() and zvol_alloc() may now be
   called in a sync task they must use KM_PUSHPAGE.

References:
  illumos/illumos-gate@681d9761e8516a7dc5ab6589e2dfe717777e1123

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes #1969
Sync /dev/zfs ioctl ordering

In order to minimize any future disruption caused by the addition
and removal /dev/zfs ioctls this patch makes the following changes.

1) Sync ZoL's ioctl ordering such that it matches Illumos.  For
   historic reasons the ZFS_IOC_DESTROY_SNAPS and ZFS_IOC_POOL_REGUID
   ioctls were out of order.

2) Move Linux and FreeBSD specific ioctls in to their own reserved
   ranges.  This allows us to preserve the existing ordering when
   new ioctls are added by either Illumos or FreeBSD.  When an
   ioctl is no longer needed it should be retired in place.

This change alters the ZFS user/kernel ABI so make sure you rebuild
both your user and kernel modules.  However, it should allow for a
much stabler interface going forward.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #1973
Update zfs(8) Snapshots section

The Snapshots section of the zfs(8) man page is incorrect and should
have been updated as part of #1312.  Snapshots of volumes can be
accessed independently and their visibility is determined by the
'snapdev=hidden|visible' property.  This is analogous to the existing
'snapdir=hidden|visible' property.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes #1921
cstyle: zvol.c

Update zvol.c to conform to the style guidelines, verified by
running cstyle.pl on the source file.  This patch contains
no functional changes.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Issue #1821
Silence e2fsck warning in zconfig.sh

When running zconfig.sh test 7 and 8 cause the following warning to
be printed to the console.  It's caused because we're snapshoting a
mounted ext2 filesystem which is not in a 'clean' state.  This is
to be expected since we have no guarentees about the on-disk
consistency of the filesystem.

EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended

To silence the warning and preserve the intent of these test cases
they have been updated to unmount the filesystem prior to snapshoting
them.  This ensures the ext2 filesystem is in a consistent state
when the snapshot is taken.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #1972
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
Register correct handlers for nvlist_{dup,pack,unpack}

This change is related to commit 81eaf15 which ensured the correct
allocation handlers were installed for nvlist_alloc().  The nvlist
functions nvlist_dup(), nvlist_pack(), and nvlist_unpack() suffer
from the same issue and have been updated accordingly.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1937
Properly handle updates of variably-sized SA entries.

During the update process in sa_modify_attrs(), the sizes of existing
variably-sized SA entries are obtained from sa_lengths[]. The case where
a variably-sized SA was being replaced neglected to increment the index
into sa_lengths[], so subsequent variable-length SAs would be rewritten
with the wrong length. This patch adds the missing increment operation
so all variably-sized SA entries are stored with their correct lengths.

Previously, a size-changing update of a variably-sized SA that occurred
when there were other variably-sized SAs in the bonus buffer would cause
the subsequent SAs to be corrupted.  The most common case in which this
would occur is when a mode change caused the ZPL_DACL_ACES entry to
change size when a ZPL_DXATTR (SA xattr) entry already existed.

The following sequence would have caused a failure when xattr=sa was in
force and would corrupt the bonus buffer:

	open(filename, O_WRONLY | O_CREAT, 0600);
	...
	lsetxattr(filename, ...);	/* create xattr SA */
	chmod(filename, 0650);		/* enlarges the ACL */

Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1978
Fix the creation of ZPOOL_HIST_CMD pool history entries.

Move the libzfs_fini() after the zpool_log_history() call so the
ZPOOL_HIST_CMD entry can get written.

Fix the handling of saved_poolname in zfsdev_ioctl()
which was broken as part of the stack-reduction work in
a16878805388c4d96cb8a294de965071d138a47b.

Since ZoL destroys the TSD data in which the previously successful
ioctl()'s pool name is stored following every vop, the ZFS_IOC_LOG_HISTORY
ioctl has a very important restriction: it can only successfully write
a long entry following a successful ioctl() if no intervening vops have
been performed.  Some of zfs subcommands do perform intervening vops and
to do the logging themselves. At the moment, the "create" and "clone"
subcommands have been modified appropriately.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1998
Add UNSHARING of filesystems and EXPORTING pools

As a 'stop' action ensure the filesystem is unshared before
it is unmounted, just in case.  Additionally, export the pool
so it may be cleanly imported by a different host.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2003
Enable /etc/mtab cache to improve performance

Re-enable the /etc/mtab cache to prevent the zfs command from
having to repeatedly open and read from the /etc/mtab file.
Instead an AVL tree of the mounted filesystems is created and
used to vastly speed up lookups. This means that if non-zfs
filesystems are mounted concurrently the 'zfs mount' will not
immediately detect them.  In practice that will rarely happen
and even if it does the absolute worst case would be a failed
mount.  This was originally disabled out of an abundance of
paranoia.

NOTE: There may still be some parts of the code which do not
consult the mtab cache.  They should be updated to check the
mtab cache as they as discovered to be a problem.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Issue #845