Export symbols for ZIL interface

These symbols are needed by consumers (i.e. Lustre) who wish to
integrate with the ZIL.  In addition the zil_rollback_destroy()
prototype was removed because the implementation of this function
was removed long ago.

Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2892
Reduce buf/dbuf mutex contention

Due to evidence of contention both the buf_hash_table and the
dbuf_hash_table sizes have been increased from 256 to 8192.

This increase in hash table size adds approximating 0.5M to
our fixed memory footprint.  This relatively small increase
is not expected to cause problems even on low memory machines.
This footprint will also become dynamic when the persistent
L2ARC support is finalized.  In the meanwhile, this small
change significantly reduces contention for certain workloads.

Signed-off-by: Chris Wedgwood <cw@f00f.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Pavel Snajdr <snajpa@snajpa.net>
Closes #1291
Fix inaccurate field descriptions

The field descriptions from arcstat.py -v for the demand accesses
are inaccurate. They all begin with "Demand Data" yet the fields
actually covered both demand data and demand meta-data accesses.

Signed-off-by: Isaac Huang <he.huang@intel.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2842
Print header properly when terminal resizes

Added a handler for SIGWINCH, so that one header
is printed per screen even when the terminal resizes.

Signed-off-by: Isaac Huang <he.huang@intel.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2847
Illumos 5213 - panic in metaslab_init due to space_map_open returning ENXIO

5213 panic in metaslab_init due to space_map_open returning ENXIO
Reviewed by: Matthew Ahrens mahrens@delphix.com
Reviewed by: George Wilson george.wilson@delphix.com

References:
  https://www.illumos.org/issues/5213
  https://reviews.csiden.org/r/110

Porting notes:

For the Linux port, KM_SLEEP was replaced with KM_PUSHPAGE.

Ported by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2745
Fix small spelling mistake

recieve becomes receive

Signed-off-by: Randall Mason <ClashTheBunny@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2877
Move a few internal ARC strucutres to arc_impl.h

Add a new file named arc_impl.h and move a few internal
ARC structure definitions into this file. This is
needed in order to allow the Linux tracepoint functions to grub
around in the internals of these structures.

Signed-off-by: Prakash Surya <prakash.surya@delphix.com>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Fix dprintf format specifiers

Fix a few dprintf format specifiers that disagreed with their argument
types.  These came to light as compiler errors when converting dprintf
to use the Linux trace buffer.  Previously this wasn't a problem,
presumably because the SPL debug logging uses vsnprintf which must
perform automatic type conversion.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
cstyle: allow right paren on its own line

Make the style checker script accept right parentheses on their own
lines. This is motivated by the Linux tracepoints macro
DECLARE_EVENT_CLASS.

The code within TP_fast_assign() (a parameter of DECLARE_EVENT_CLASS)
is normal C assignments terminated by semicolons.  But the style
checker forbids us from following a semicolon with a non-blank and
from preceding a right parenthesis with white space.  Therefore the
closing parenthesis must go on the next line, yet the style checker
foribs us from indenting it for readability.  Relaxing the
no-non-blank-after-semicolon rule would open the door to too many bad
style practices. So instead we relax the
no-white-space-before-right-paren rule if the parenthesis is on its
own line.  The relaxation is overriden with the -p option so we still
have a way to catch misuse of this style.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Swap DTRACE_PROBE* with Linux tracepoints

This patch leverages Linux tracepoints from within the ZFS on Linux
code base. It also refactors the debug code to bring it back in sync
with Illumos.

The information exported via tracepoints can be used for a variety of
reasons (e.g. debugging, tuning, general exploration/understanding,
etc). It is advantageous to use Linux tracepoints as the mechanism to
export this kind of information (as opposed to something else) for a
number of reasons:

    * A number of external tools can make use of our tracepoints
      "automatically" (e.g. perf, systemtap)
    * Tracepoints are designed to be extremely cheap when disabled
    * It's one of the "accepted" ways to export this kind of
      information; many other kernel subsystems use tracepoints too.

Unfortunately, though, there are a few caveats as well:

    * Linux tracepoints appear to only be available to GPL licensed
      modules due to the way certain kernel functions are exported.
      Thus, to actually make use of the tracepoints introduced by this
      patch, one might have to patch and re-compile the kernel;
      exporting the necessary functions to non-GPL modules.

    * Prior to upstream kernel version v3.14-rc6-30-g66cc69e, Linux
      tracepoints are not available for unsigned kernel modules
      (tracepoints will get disabled due to the module's 'F' taint).
      Thus, one either has to sign the zfs kernel module prior to
      loading it, or use a kernel versioned v3.14-rc6-30-g66cc69e or
      newer.

Assuming the above two requirements are satisfied, lets look at an
example of how this patch can be used and what information it exposes
(all commands run as 'root'):

    # list all zfs tracepoints available

    $ ls /sys/kernel/debug/tracing/events/zfs
    enable              filter              zfs_arc__delete
    zfs_arc__evict      zfs_arc__hit        zfs_arc__miss
    zfs_l2arc__evict    zfs_l2arc__hit      zfs_l2arc__iodone
    zfs_l2arc__miss     zfs_l2arc__read     zfs_l2arc__write
    zfs_new_state__mfu  zfs_new_state__mru

    # enable all zfs tracepoints, clear the tracepoint ring buffer

    $ echo 1 > /sys/kernel/debug/tracing/events/zfs/enable
    $ echo 0 > /sys/kernel/debug/tracing/trace

    # import zpool called 'tank', inspect tracepoint data (each line was
    # truncated, they're too long for a commit message otherwise)

    $ zpool import tank
    $ cat /sys/kernel/debug/tracing/trace | head -n35
    # tracer: nop
    #
    # entries-in-buffer/entries-written: 1219/1219   #P:8
    #
    #                              _-----=> irqs-off
    #                             / _----=> need-resched
    #                            | / _---=> hardirq/softirq
    #                            || / _--=> preempt-depth
    #                            ||| /     delay
    #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
    #              | |       |   ||||       |         |
            lt-zpool-30132 [003] .... 91344.200050: zfs_arc__miss: hdr...
          z_rd_int/0-30156 [003] .... 91344.200611: zfs_new_state__mru...
            lt-zpool-30132 [003] .... 91344.201173: zfs_arc__miss: hdr...
          z_rd_int/1-30157 [003] .... 91344.201756: zfs_new_state__mru...
            lt-zpool-30132 [003] .... 91344.201795: zfs_arc__miss: hdr...
          z_rd_int/2-30158 [003] .... 91344.202099: zfs_new_state__mru...
            lt-zpool-30132 [003] .... 91344.202126: zfs_arc__hit: hdr ...
            lt-zpool-30132 [003] .... 91344.202130: zfs_arc__hit: hdr ...
            lt-zpool-30132 [003] .... 91344.202134: zfs_arc__hit: hdr ...
            lt-zpool-30132 [003] .... 91344.202146: zfs_arc__miss: hdr...
          z_rd_int/3-30159 [003] .... 91344.202457: zfs_new_state__mru...
            lt-zpool-30132 [003] .... 91344.202484: zfs_arc__miss: hdr...
          z_rd_int/4-30160 [003] .... 91344.202866: zfs_new_state__mru...
            lt-zpool-30132 [003] .... 91344.202891: zfs_arc__hit: hdr ...
            lt-zpool-30132 [001] .... 91344.203034: zfs_arc__miss: hdr...
          z_rd_iss/1-30149 [001] .... 91344.203749: zfs_new_state__mru...
            lt-zpool-30132 [001] .... 91344.203789: zfs_arc__hit: hdr ...
            lt-zpool-30132 [001] .... 91344.203878: zfs_arc__miss: hdr...
          z_rd_iss/3-30151 [001] .... 91344.204315: zfs_new_state__mru...
            lt-zpool-30132 [001] .... 91344.204332: zfs_arc__hit: hdr ...
            lt-zpool-30132 [001] .... 91344.204337: zfs_arc__hit: hdr ...
            lt-zpool-30132 [001] .... 91344.204352: zfs_arc__hit: hdr ...
            lt-zpool-30132 [001] .... 91344.204356: zfs_arc__hit: hdr ...
            lt-zpool-30132 [001] .... 91344.204360: zfs_arc__hit: hdr ...

To highlight the kind of detailed information that is being exported
using this infrastructure, I've taken the first tracepoint line from the
output above and reformatted it such that it fits in 80 columns:

    lt-zpool-30132 [003] .... 91344.200050: zfs_arc__miss:
        hdr {
            dva 0x1:0x40082
            birth 15491
            cksum0 0x163edbff3a
            flags 0x640
            datacnt 1
            type 1
            size 2048
            spa 3133524293419867460
            state_type 0
            access 0
            mru_hits 0
            mru_ghost_hits 0
            mfu_hits 0
            mfu_ghost_hits 0
            l2_hits 0
            refcount 1
        } bp {
            dva0 0x1:0x40082
            dva1 0x1:0x3000e5
            dva2 0x1:0x5a006e
            cksum 0x163edbff3a:0x75af30b3dd6:0x1499263ff5f2b:0x288bd118815e00
            lsize 2048
        } zb {
            objset 0
            object 0
            level -1
            blkid 0
        }

For the specific tracepoint shown here, 'zfs_arc__miss', data is
exported detailing the arc_buf_hdr_t (hdr), blkptr_t (bp), and
zbookmark_t (zb) that caused the ARC miss (down to the exact DVA!).
This kind of precise and detailed information can be extremely valuable
when trying to answer certain kinds of questions.

For anybody unfamiliar but looking to build on this, I found the XFS
source code along with the following three web links to be extremely
helpful:

    * http://lwn.net/Articles/379903/
    * http://lwn.net/Articles/381064/
    * http://lwn.net/Articles/383362/

I should also node the more "boring" aspects of this patch:

    * The ZFS_LINUX_COMPILE_IFELSE autoconf macro was modified to
       support a sixth paramter. This parameter is used to populate the
       contents of the new conftest.h file. If no sixth parameter is
       provided, conftest.h will be empty.

    * The ZFS_LINUX_TRY_COMPILE_HEADER autoconf macro was introduced.
      This macro is nearly identical to the ZFS_LINUX_TRY_COMPILE macro,
      except it has support for a fifth option that is then passed as
      the sixth parameter to ZFS_LINUX_COMPILE_IFELSE.

These autoconf changes were needed to test the availability of the Linux
tracepoint macros. Due to the odd nature of the Linux tracepoint macro
API, a separate ".h" must be created (the path and filename is used
internally by the kernel's define_trace.h file).

    * The HAVE_DECLARE_EVENT_CLASS autoconf macro was introduced. This
      is to determine if we can safely enable the Linux tracepoint
      functionality. We need to selectively disable the tracepoint code
      due to the kernel exporting certain functions as GPL only. Without
      this check, the build process will fail at link time.

In addition, the SET_ERROR macro was modified into a tracepoint as well.
To do this, the 'sdt.h' file was moved into the 'include/sys' directory
and now contains a userspace portion and a kernel space portion. The
dprintf and zfs_dbgmsg* interfaces are now implemented as tracepoint as
well.

Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Merge branch 'b_tracepoints'

Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2874
Undirty freed spill blocks.

If a spill block's dbuf hasn't yet been written when a spill block is
freed, the unwritten version will still be written.  This patch handles
the case in which a spill block's dbuf is freed and undirties it to
prevent it from being written.

The most common case in which this could happen is when xattr=sa is being
used and a long xattr is immediately replaced by a short xattr as in:

	setfattr -n user.test -v very_very_very..._long_value  <file>
	setfattr -n user.test -v short_value  <file>

The first value must be sufficiently long that a spill block is generated
and the second value must be short enough to not require a spill block.
In practice, this would typically happen due to internal xattr operations
as a result of setting acltype=posixacl.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2663
Closes #2700
Closes #2701
Closes #2717
Closes #2863
Closes #2884
Prevent ZFS leaking pool free space

When processing async destroys ZFS would leak space every txg timeout
(5 seconds by default), if no writes occurred, until the pool is totally
full. At this point it would be unfixable without a pool recreation.

In addition if the machine was rebooted with the pool in this situation
would fail to import on boot, hanging indefinitely, as the import process
requires the ability to write data to the pool. Any attempts to query
the pool status during the hung import would not return as the import
holds the pool lock.

The only way to import such a pool would be to specify -o readonly=on
to the zpool import.

zdb -bb <pool> can be used to check for "deferred free" size which is
where this lost space will be counted.

References:
  https://github.com/freebsd/freebsd/commit/48431b7
  http://svnweb.freebsd.org/base?view=revision&revision=273158
  https://reviews.csiden.org/r/132/

Porting notes:

This issue was filed as illumos 5347 and a more comprehensive fix is
under review.  Once that change is finalized it will be integrated, in
the meanwhile the FreeBSD fix has been merged to prevent the issue.

Ported by: Tim Chase <tim@chase2k.com>
Signed-off-by: Matthew Ahrens mahrens@delphix.com
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2896
Fix improper null-byte termination handling

Fix a few cases where null-byte termination of strings was done
unnecessarily or incorrectly.

- The snprintf() function always produces a null-byte terminated string
  for non-negative return values, so it is not necessary to write out a
  null-byte as a separate step.

- Also, it is unsafe to use the return value of snprintf() as an offset
  for placing a null-byte, because if the output was truncated the return
  value is the number of bytes that _would_ have been written had enough
  space been available. Therefore the return value may index beyond the
  array boundaries.

- Finally, snprintf() accounts for the null-byte when limiting its output
  size, so there is no need to pass it a size parameter that is one less
  than the buffer size.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2875
Explicitly include SPL compat headers

Inclusion of SPL compatibility headers was moved out of the public
header sys/types.h to avoid conflicts with external packages.  Include a
few compatiblity headers explicitly to cope with that change.  Also,
sort some linux-specific inclusions alphabetically.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2898
bio_alloc() with __GFP_WAIT never returns NULL

Mark the error handling branch as unlikely() because the current
kernel interface can never return NULL.  However, we want to keep
the error handling in case this behavior changes in the futre.

Plus fix a small style issue.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Isaac Huang <he.huang@intel.com>
Closes #2703
Fix systemd config for zfs-share.service

The zfs-share.service rule needs to be modified to ensure that it
does not execute before zfs-mount.service.

Signed-off-by: Dan Swartzendruber <dswartz@druber.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ralf Ertzinger <ralf@skytale.net>
Closes #2893
Fix snapshots with dirty inodes

Filesystems which are mounted read-only or are immutable because
they are snapshots must not be allowed to dirty and inode.  This
will result in a write which will correctly cause a kernel panic
because these filesystem are (and must be) immutable.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2812
1099: turbo/iscsi - This is iSCSI sharing for ZoL (shareiscsi).
* Supports the following iSCSI implementations (in this order of discovery):
  + IET         http://iscsitarget.sourceforge.net
  + STGT        http://stgt.berlios.de
  + SCST        http://scst.sourceforge.net
    + Requires that SCST was compiled with /sys support (the default).
  + LIO         http://linux-iscsi.org
* Will refuse to unshares an active target (one with sessions).
* Supports the following options to the 'shareiscsi' property:
  + name/iqn    Full iSCSI Qualified Name (IQN), including identifier.
                This is generated by iscsi_generate_target():
                + Uses the content of an optional /etc/iscsi_target_id file:
                  Example: iqn.YYYY-MM.tld.domain
                + If this file doesn't exist, it uses the current year, month
                  and domain name to generate the iqn.
                + The dataset name is appended at the end of the iqn, with
                  slashes replaced with dots.
                  => <iqn>:<dataset>
  + lun         LUN (0-16384)
                Default: 0 (1 for STGT)
  + type        Share mode (fileio, blockio, nullio, disk, tape)
                STGT: ssc, pt
                Default: blockio (disk for STGT)
  + iomode      IO mode (wb, wt, ro)
                STGT: rdwr, aio, mmap, sg, ssc
                Default: wt (rdwr for STGT)
  + blocksize   Logical block size (512, 1024, 2048, 4096)
                Default: Volume blocksize, 4096 if not usable.
                NOTE: Currently not supported for STGT (doesn't seem to be
                      an option for it in tgtadm).
  + initiator   Allow only this initiator to bind to target.
                Currently only availible for LIO, STGT and SCST.
  + authname    Global user to use in binds on targets.
  + authpass    Password for global user.
* If not called with a 'name/iqn' value, then force setting it.
  This so that the IQN doesn't change every month (when it is
  regenerated again). It will be generated by iscsi_generate_target()
  (see above).

NOTE:
+ Moved nfs.c:foreach_nfs_shareopt() to libshare.c:foreach_shareopt()
  so that it can be (re)used in smb.c and iscsi.c.
+ Split iSCSI implementation into their own separate source files
+ Use the list_{create,insert}() etc for keeping tabs of the linked lists
  instead of using a home-made version.
+ A half second delay had to be added in lib/libzfs/libzfs_mount.c:zfs_unmount()
  after the successful unshare. This to avoid 'dataset busy' when destroying
  recursivly.
= The 'initiator', 'authname' and 'authpass' option might have some issues:
  It will make the compatibility between the different iSCSI implementations
  questionable - can't switch between them easily (it will ONLY be availible
  in ZoL). I COULD make the option be silently ignored (instead of forcibly
  rejected if not availible).

  But that still doesn't solve the (possible) problem between ZoL and
  OpenZFS/Illumos (setting the option, will possibly introduce problems when
  importing the pool on something else than ZoL).

  So some more discussion might be needed..
* Misc iSCSI fixes/cleanups/attempts to get 'zfs rename' to work.
  !! Doesn't - a 'zfs rename' works, but most often than not, the rename
  !! IOCTL hangs. Not every time and not always on the first dataset being
  !! renamed... Seems a little to random to me.
1476: turbo/smbfs_registry-shares - Rewrite of the Libshare/SMBFS
* Add support for options to 'sharesmb'.
  Fixes: #1182
  + Move nfs.c:foreach_nfs_shareopt() to libshare.c:foreach_shareopt()
    so that it can be (re)used in smb.c (and later iscsi.c).
  + Call net(8) with the guest_ok option.
  + Rewrite the sharesmb part of the zfs(8) manpage.
    + Add more examples
    + Inform about the (new) options to sharesmb.
  + Add STDERR_VERBOSE to libzfs_run_process() so that we
    can catch any errors from net(8).
  + Don't call smb_retrieve_shares() after enabling a share.
    No point, it's done when really needed anyway.
  + Support 'y', 'yes' and 'true' for guest_ok.
  * If sharesmb=on, just exit cleanly directly at the top of
    get_smb_shareopts_cb().
  * Remove param 2 and 3 from smb_enable_share_one(). That is
    availible in the first param - the impl_share struct.
  * Extra debugging added in smb_enable_share_one() - print
    all our options just before we call net(8).
* Add support for optional, extra script /sbin/zfs_share_smbfs
  to run after shareing is done.
  + Add an example zfs_share_smbfs script
* The option sharesmb should not be inherited by childs.
  Samba is perfectly able to show child file systems...
* Use dataset name in comment, not the smb share name.
* Use REGISTRY SHARES instead of USER SHARES
  + These are a lot more configurable (more possibility to customize the share).
  + Remove the 'acl' option and replace it with 'writeable' instead.
  + On some machines, there is a "global" share. This isn't really a share,
    but the possibility to modify global options. So first get a line of
    _real_ shares using 'net conf listshares' and _then_ cyckle through
    them retrieving info with 'net conf showshare <share>'.
  + Add an example on how to modify a share after ZFS share and what man
    pages to use for more info.
* Speedups (less share retreivals) and make sure the 'net' command is executable.
  + Since smb_shares is global, we only retreive shares if it's NULL
    in smb_retrieve_shares(). It should limit the number of times we
    fork() and read shares (which takes time).
  + If the net command don't exist (is executable), don't even register
    the smb fstype in libshare_smb_init().
  + access() fix - check if NET_CMD_PATH is _executable_ not just 'exists'.
* Run cstyle.pl to fix any code style problems.
* Output error if 'net' can't talk to samba.
* Improve error message if 'net' isn't executable.
* Move the checks from smb_available() to libshare_smb_init()
  to avoid doing them multiple times.
* Convert homemade linked list to the ZFS versions list_* functions (which uses a link_t).
* Script to list SMB shares added.
* Comment out a call to zfs_unshare_smb(). Don't seem to be needed.
  This because zfs_unshare_smb() is called twice if setting 'sharesmb=off' - once
  'somewhere else' and once here (this one AFTER the share have been unshared). That
  makes this one fail! Don't know if this is correct, but it works to comment out this...