Update the dbuf__evict__one() tracepoint so that it can safely
handle a NULL dmu_buf_impl_t pointer.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
Signed-off-by: gaurkuma <gauravk.18@gmail.com>
Closes#6463
Log contents of a receive record if an error occurs while writing
it out to the pool. This may help determine the cause when backup
streams are rejected as invalid.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes#6465
When performing concurrent object allocations using the new
multi-threaded allocator and large dnodes it's possible to
allocate overlapping large dnodes.
This case should have been handled by detecting an error
returned by dnode_hold_impl(). But that logic only checked
the returned dnp was not-NULL, and the dnp variable was not
reset to NULL when retrying. Resolve this issue by properly
checking the return value of dnode_hold_impl().
Additionally, it was possible that dnode_hold_impl() would
misreport a dnode as free when it was in fact in use. This
could occurs for two reasons:
* The per-slot zrl_lock must be held over the entire critical
section which includes the alloc/free until the new dnode
is assigned to children_dnodes. Additionally, all of the
zrl_lock's in the range must be held to protect moving
dnodes.
* The dn->dn_ot_type cannot be solely relied upon to check
the type. When allocating a new dnode its type will be
DMU_OT_NONE after dnode_create(). Only latter when
dnode_allocate() is called will it transition to the new
type. This means there's a window when allocating where
it can mistaken for a free dnode.
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Ned Bass <bass6@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#6414Closes#6439
taskq work item to more than one queue concurrently. Also, please
see discussion in zfsonlinux/zfs#3840.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Boris Protopopov <boris.protopopov@actifio.com>
Closes#609
The vdev_id script requires awk, grep, and head. Use dracut_install to
ensure that these commands are available in the initrd environment.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Karsten Kretschmer <kkretschmer@gmail.com>
Closes#6443Closes#6452
taskq_seq_show_impl walks the tq_active_list to show the tqent_func and
tqent_arg. However for taskq_dispatch_ent, it's very likely that the
task entry will be freed during the function call, and causes a
use-after-free bug.
To fix this, we duplicate the task entry to an on-stack struct, and
assign it instead to tqt_task. This way, the tq_lock alone will
guarantee its safety.
Reviewed-by: Tim Chase <tim@chase2k.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes#638Closes#640
gcc-7 seems to use __udivmoddi4 for 64-bit division on 32-bit arch. This
patch implement them so we don't get undefined reference error.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes zfsonlinux/zfs#6417
Closes#636
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Sen Haerens <sen@senhaerens.be>
Closes#6444Closes#6445
This is consistent with the change introduced in bc2d809 where
'zpool get -p dedupratio' does not add a trailing "x" to the output.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#6436Closes#6449
rsend tests in the test suite frequently create and
destroy datasets. It is possible for zfs destroy to
return an error code indicating the dataset is busy.
Simply use a log_must_busy in these cases to retry
destroying those datasets. Other fixes to rsend test
cases to avoid unmounting and remounting filesystems
and some cleanup.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#6418
Update many return and assignment statements to follow the convention
of using the SET_ERROR macro when returning a hard-coded non-zero
value from a function. This aids debugging by recording the error
codes in the debug log.
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes#6441
It is just plain unsafe to peek inside in-kernel
mutex structure and make assumptions about what kernel
does with those internal fields like owner.
Kernel is all too happy to stop doing the expected things
like tracing lock owner once you load a tainted module
like spl/zfs that is not GPL.
As such you will get instant assertion failures like this:
VERIFY3(((*(volatile typeof((&((&zo->zo_lock)->m_mutex))->owner) *)&
((&((&zo->zo_lock)->m_mutex))->owner))) ==
((void *)0)) failed (ffff88030be28500 == (null))
PANIC at zfs_onexit.c:104:zfs_onexit_destroy()
Showing stack for process 3626
CPU: 0 PID: 3626 Comm: mkfs.lustre Tainted: P OE ------------ 3.10.0-debug #1
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Call Trace:
dump_stack+0x19/0x1b
spl_dumpstack+0x44/0x50 [spl]
spl_panic+0xbf/0xf0 [spl]
zfs_onexit_destroy+0x17c/0x280 [zfs]
zfsdev_release+0x48/0xd0 [zfs]
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Reviewed-by: Gvozden Neskovic <neskovic@gmail.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Closes#639Closes#632
Prevent race on accessing kmutex_t when the mutex is
embedded in a ref counted structure.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Closes zfsonlinux/zfs#6401
Closes#637
This reverts commit d89616fda8 which
introduced some build failures which need to be resolved before
this can be merged.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #633
It is just plain unsafe to peek inside in-kernel
mutex structure and make assumptions about what kernel
does with those internal fields like owner.
Kernel is all too happy to stop doing the expected things
like tracing lock owner once you load a tainted module
like spl/zfs that is not GPL.
As such you will get instant assertion failures like this:
VERIFY3(((*(volatile typeof((&((&zo->zo_lock)->m_mutex))->owner) *)&
((&((&zo->zo_lock)->m_mutex))->owner))) ==
((void *)0)) failed (ffff88030be28500 == (null))
PANIC at zfs_onexit.c:104:zfs_onexit_destroy()
Showing stack for process 3626
CPU: 0 PID: 3626 Comm: mkfs.lustre Tainted: P OE ------------ 3.10.0-debug #1
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Call Trace:
dump_stack+0x19/0x1b
spl_dumpstack+0x44/0x50 [spl]
spl_panic+0xbf/0xf0 [spl]
zfs_onexit_destroy+0x17c/0x280 [zfs]
zfsdev_release+0x48/0xd0 [zfs]
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Closes#632Closes#633
While investigating https://github.com/zfsonlinux/zfs/issues/6425 I
noticed that ioctl ZIOs were not setting zio->io_delay correctly. They
would set the start time in zio_vdev_io_start(), but never set the end
time in zio_vdev_io_done(), since ioctls skip it and go straight to
zio_done(). This was causing spurious "delayed IO" events to appear,
which would eventually get rate-limited and displayed as
"Missed events" messages in zed.
To get around the problem, this patch only sets zio->io_delay for read
and write ZIOs, since that's all we care about anyway.
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes#6425Closes#6440
Use kstat to get a more accurate count of uberblock updates.
Using a loop with zdb can potentially miss some uberblocks.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#6407Closes#6419
At import time spa_import() calls zvol_create_minors() directly: with
the current implementation we have no way to avoid device node
creation when volmode=none.
Fix this by enforcing volmode=none directly in zvol_alloc().
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#6426
Add aarch64 to the list of architecture which do not sanitize the
LDFLAGS from the environment. See fb963d33 for details.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#6424
Add aarch64 to the list of architecture which do not sanitize the
LDFLAGS from the environment. See e0aacd9b for details.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#635
Test case zfs_send_007_pos regularly is killed
by test-runner during zfs-tests on buildbot. Disable
it for now until further investigation can be done.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#6422
If we are in the middle of an incremental 'zfs receive', the child
.../%recv will exist. If we run 'zfs promote' .../%recv, it will "work",
but then zfs gets confused about the status of the new dataset.
Attempting to do this promote should be an error.
Similarly renaming .../%recv datasets should not be allowed.
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#4843Closes#6339
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: bunder2015 <omfgbunder@gmail.com>
Closes#6409Closes#6410
Redefine the SET_ERROR macro in terms of __dprintf() so the error
return codes get logged as both tracepoint events (if tracepoints are
enabled) and as ZFS debug log entries. This also allows us to use
the same definition of SET_ERROR() in kernel and user space.
Define a new debug flag ZFS_DEBUG_SET_ERROR=512 that may be bitwise
or'd into zfs_flags. Setting this flag enables both dprintf() and
SET_ERROR() messages in the debug log. That is, setting
ZFS_DEBUG_SET_ERROR and ZFS_DEBUG_DPRINTF|ZFS_DEBUG_SET_ERROR are
equivalent (this was done for sake of simplicity). Leaving
ZFS_DEBUG_SET_ERROR unset suppresses the SET_ERROR() messages which
helps avoid cluttering up the logs.
To enable SET_ERROR() logging, run:
echo 1 > /sys/module/zfs/parameters/zfs_dbgmsg_enable
echo 512 > /sys/module/zfs/parameters/zfs_flags
Remove the zfs_set_error_class tracepoints event class since
SET_ERROR() now uses __dprintf(). This sacrifices a bit of
granularity when selecting individual tracepoint events to enable but
it makes the code simpler.
Include file, function, and line number information in debug log
entries. The information is now added to the message buffer in
__dprintf() and as a result the zfs_dprintf_class tracepoints event
class was changed from a 4 parameter interface to a single parameter.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes#6400
In unattended operations it's often more useful to have node
panic and reboot when it encounters problems as opposed to
sit there indefinitely waiting for somebody to discover it.
This implements an spl_panic_crash module parameter, set it
to nonzero to cause spl_panic() to call panic().
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Closes#634
The userobj_accounting feature described in the zpool-features.5
man page was incorrectly indented. Fix it.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#6402
Check in the DMU whether an object record in a send stream being
received contains an unsupported dnode slot count, and return an
error if it does. Failure to catch an unsupported dnode slot count
would result in a panic when the SPA attempts to increment the
reference count for the large_dnode feature and the pool has the
feature disabled. This is not normally an issue for a well-formed
send stream which would have the DMU_BACKUP_FEATURE_LARGE_DNODE flag
set if it contains large dnodes, so it will be rejected as
unsupported if the required feature is disabled. This change adds a
missing object record field validation.
Add missing stream feature flag checks in
dmu_recv_resume_begin_check().
Consolidate repetitive comment blocks in dmu_recv_begin_check().
Update zstreamdump to print the dnode slot count (dn_slots) for an
object record when running in verbose mode.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes#6396
'zpool clear' should be able to resume I/O on suspended, but otherwise
healthy, pools.
4a283c7 accidentally introduced a new code path where we call
txg_wait_synced() on the suspended pool before we had the chance to
resume I/O via zio_resume(): this results in the 'zpool clear'
command hanging indefinitely, waiting for a TXG that cannot be synced.
Fix this by avoiding the call to txg_wait_synced().
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#6399
The previous autoconf test for the presence of super_setup_bdi_name()
uses an invocation with an incorrect type signature, producing a
warning by the compiler when the test is run. This gets elevated to an
error when compiling with -Werror=format-security, causing autoconf to
falsely infer super_setup_bdi_name() is not present. This updates the
testing code to match the invocation used in
include/linux/vfs_compat.h.
Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Justin Bedo <cu@cua0.org>
Closes#6398
There is no need to perform the activity check before detecting that the
user must set the system hostid, because the pool's multihost property
is on, but spa_get_hostid() returned 0. The initial call to
vdev_uberblock_load() provided the information required.
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#6388
Add a callback to wake all running mmp threads when
zfs_multihost_interval is changed.
This is necessary when the interval is changed from a very large value
to a significantly lower one, while pools are imported that have the
multihost property enabled.
Without this commit, the mmp thread does not wake up and detect the new
interval until after it has waited the old multihost interval time. A
user monitoring mmp writes via the provided kstat would be led to
believe that the changed setting did not work.
Added a test in the ZTS under mmp to verify the new functionality is
working.
Added a test to ztest which starts and stops mmp threads, and calls into
the code to signal sleeping mmp threads, to test for deadlocks or
similar locking issues.
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#6387
"zhack feature stat" performs a read-only import, so the MMP activity
check is not necessary.
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#6388Closes#6389
Turning the multihost property on requires that a hostid be set to allow
ZFS to determine when a foreign system is attemping to import a pool.
The error message instructing the user to set a hostid refers to
genhostid(1).
Genhostid(1) is not available on SUSE Linux. This commit adds a script
modeled after genhostid(1) for those users.
Zgenhostid checks for an /etc/hostid file; if it does not exist, it
creates one and stores a value. If the user has provided a hostid as an
argument, that value is used. Otherwise, a random hostid is generated
and stored.
This differs from the CENTOS 6/7 versions of genhostid, which overwrite
the /etc/hostid file even though their manpages state otherwise.
A man page for zgenhostid is added. The one for genhostid is in (1), but
I put zgenhostid in (8) because I believe it's more appropriate.
The mmp tests are modified to use zgenhostid to set the hostid instead
of using the spl_hostid module parameter. zgenhostid will not replace
an existing /etc/hostid file, so new mmp_clear_hostid calls are
required.
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#6358Closes#6379
The config lock must be held for the duration of the MMP write.
Since the I/Os are executed via map_nowait(), the done function
is the only place where we know the write has completed.
Since SCL_STATE is taken as reader, overlapping I/Os do not
create a deadlock. The refcount is simply increased when new
I/Os are queued and decreased when I/Os complete.
Test case added which exercises the probe IO call path to
verify the fix and prevent a regression.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#6394
This reverts commit cc9c6bc, which has been causing intermittent
test failures on buildbot. A correct fix for this locking issue
has been applied in a separate patch.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
In zed event test cases, a brief delay was introduced
to allow for events to make it to the zed log. On at least
one buildbot builder, the 1 second delay is not long enough.
Therefore, increasing the delay should ensure the zed has
more than enough time to write to its log.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#6395
If we're creating a pool with version >= SPA_VERSION_DSL_SCRUB (v11)
we need to account for additional space needed by the origin dataset
which will also be snapshotted: "poolname"+"/"+"$ORIGIN"+"@"+"$ORIGIN".
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#6374
When replacing a disk with non-wholedisk spare, we shouldn't zero_label
it. The wholedisk case already skip it. In fact, zero_label function
will fail saying device busy because it's already opened exclusively,
but since there's no error checking, the replace command will succeed,
causing great confusion.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes#6369
zpool iostat/status -c is supposed to be restricted
by its search path, but currently isn't. To prevent
arbitrary scripts from being executed, disallow '/'
from commands.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#6353Closes#6359
Commit 379ca9c Multi-modifier protection (MMP) used HZ to convert
nanoseconds to ticks for use with cv_timedwait() and ddi_get_lbolt().
The correct macro is hz, which is defined within the SPL for kernel
space, and within zfs_context.h for user space.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#6357Closes#6360
CID 165755: Division or modulo by zero (DIVIDE_BY_ZERO)
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#6352
Use log_must_busy when destroying the snapshot
and dataset during cleanup in zfs_mount_001_neg.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#6382
This change allows mountpoint_003_pos and send-c_props
to run on Linux kernels that do not support mandatory
locking. Linux kernel versions greater than or equal to
4.4 no longer support mandatory locking and the test
suite will now account for that.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#6346Closes#6347Closes#6362
zvol_misc_002_pos was failing on Fedora 26 because its newer version
of fsck was returning a different code than previous versions. The
new fsck error code is valid and is been added to the test in this
patch.
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes#6350
When we load a ZFS pool having spa_name equals to some existing kstat
we would have to create a duplicate entry, which procfs doesn't like.
For instance a ZFS pool named "zil" would have its kstat "txgs"
(module "zfs/zil") intalled under "/proc/spl/kstat/zfs/zil":
unfortunately we already have a kstat named "zil" (module "zfs")
installed in the same procfs location.
Avoid this issue by skipping the duplicate entry creation in procfs.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#628
