[bio] The req_op enum was changed to req_opf. Update the "Linux 4.8 API"
autotools checks to use an int to determine whether the various REQ_OP
values are defined. This should work properly on kernels >= 4.8.
[bio] bio_set_op_attrs() is now an inline function and can't be detected
with #ifdef. Add a configure check to determine whether bio_set_op_attrs()
is defined. Move the local definition of it from vdev_disk.c to
blkdev_compat.h for consistency with other related compability shims.
[bio] The read/write flags and their modifiers, including WRITE_FLUSH,
WRITE_FUA and WRITE_FLUSH_FUA have been removed from fs.h. Add the new
bio_set_flush() compatibility wrapper to replace VDEV_WRITE_FLUSH_FUA
and set the flags appropriately for each supported kernel version.
[vfs] The generic_readlink() function has been made static. If .readlink
in inode_operations is NULL, generic_readlink() is used.
[zol typo] Completely unrelated to 4.10 compat, fix a typo in the check
for REQ_OP_SECURE_ERASE so that the proper macro is defined:
s/HAVE_REQ_OP_SECURE_DISCARD/HAVE_REQ_OP_SECURE_ERASE/
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes#5499
The HAVE_BIO_RW_* #ifdef's must appear before REQ_* #ifdef's
in the bio_is_flush() and bio_is_discard() macros. Linux 2.6.32
era kernels defined both of values and the HAVE_BIO_RW_* must be
used in this case. This resulted in a panic in zconfig test 5.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes#4951Closes#4959
Non-Linux OpenZFS implementations require additional support to be
used a root pool. This code should simply be removed to avoid
confusion and improve readability.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes#4951
Prior to b39c22b, which was first generally available in the 0.6.5
release as b39c22b, ZoL never actually submitted synchronous read or write
requests to the Linux block layer. This means the vdev_disk_dio_is_sync()
function had always returned false and, therefore, the completion in
dio_request_t.dr_comp was never actually used.
In b39c22b, synchronous ZIO operations were translated to synchronous
BIO requests in vdev_disk_io_start(). The follow-on commits 5592404 and
aa159af fixed several problems introduced by b39c22b. In particular,
5592404 introduced the new flag parameter "wait" to __vdev_disk_physio()
but under ZoL, since vdev_disk_physio() is never actually used, the wait
flag was always zero so the new code had no effect other than to cause
a bug in the use of the dio_request_t.dr_comp which was fixed by aa159af.
The original rationale for introducing synchronous operations in b39c22b
was to hurry certains requests through the BIO layer which would have
otherwise been subject to its unplug timer which would increase the
latency. This behavior of the unplug timer, however, went away during the
transition of the plug/unplug system between kernels 2.6.32 and 2.6.39.
To handle the unplug timer behavior on 2.6.32-2.6.35 kernels the
BIO_RW_UNPLUG flag is used as a hint to suppress the plugging behavior.
For kernels 2.6.36-2.6.38, the REQ_UNPLUG macro will be available and
ise used for the same purpose.
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#4858
Originally, these two function are inline, so their usability is tied to
posix_acl_release. However, since Linux 3.14, they became EXPORT_SYMBOL, so we
can always use them. In this patch, we create an independent test for these
two functions so we can use them when possible.
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Currently every calls to zpl_posix_acl_release will schedule a delayed task,
and each delayed task will add a timer. This used to be fine except for
possibly bad performance impact.
However, in Linux 4.8, a new timer wheel implementation[1] is introduced. In
this new implementation, the larger the delay, the less accuracy the timer is.
So when we have a flood of timer from zpl_posix_acl_release, they will expire
at the same time. Couple with the fact that task_expire will do linear search
with lock held. This causes an extreme amount of contention inside interrupt
and would actually lockup the system.
We fix this by doing batch free to prevent a flood of delayed task. Every call
to zpl_posix_acl_release will put the posix_acl to be freed on a lockless
list. Every batch window, 1 sec, the zpl_posix_acl_free will fire up and free
every posix_acl that passed the grace period on the list. This way, we only
have one delayed task every second.
[1] https://lwn.net/Articles/646950/
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
This patch ensures that all systemd services are processed through the
systemd scriptlets, so that services are properly configured per the
preset file installed by the package.
Without this, zfs.target is set, but none of the services are enabled per
the preset file, meaning automounting filesystems and such won't work
out of the box.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Neal Gompa <ngompa13@gmail.com>
Closes#5356
This is caught by kmemleak when running compress_004_pos
Reviewed-by: Tim Chase <tim@chase2k.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes#5244Closes#5330
Ubuntu added support for checking inode permissions to lookup_bdev() in kernel
commit 193fb6a2c94fab8eb8ce70a5da4d21c7d4023bee (merged in 4.4.0-6.21).
Upstream bug: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1636517
This patch adds a test for Ubuntu's variant of lookup_bdev() to configure and
calls the function in the correct way.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Hajo Möller <dasjoe@gmail.com>
Closes#5336
The variable snapprops_nvlist was never initialized, so properties
were not applied to the received snapshot.
Additionally, add zfs_receive_013_pos.ksh script to ZFS test suite to exercise
'zfs receive' functionality for user properties.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#4338
This is as much an upstream compatibility as it's a bit of a performance
gain.
The illumos taskq implemention doesn't allow a TASKQ_THREADS_CPU_PCT type
to be dynamic and in fact enforces as much with an ASSERT.
As to performance, if this taskq is dynamic, it can cause excessive
contention on tq_lock as the threads are created and destroyed because it
can see bursts of many thousands of tasks in a short time, particularly
in heavy high-concurrency zvol write workloads.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes#5236
While stack size will vary by architecture it has historically defaulted to
8K on x86_64 systems. However, as of Linux 3.15 the default thread stack
size was increased to 16K. These kernels are now the default in most non-
enterprise distributions which means we no longer need to assume 8K stacks.
This patch takes advantage of that fact by appropriately reverting stack
conservation changes which were made to ensure stability. Changes which
may have had a negative impact on performance for certain workloads. This
also has the side effect of bringing the code slightly more in line with
upstream.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Closes#4059
Call mount and umount via /usr/bin/env instead of /bin/sh in
zfsctl_snapshot_mount() and zfsctl_snapshot_unmount().
This change fixes a shell code injection flaw. The call to /bin/sh
passed the mountpoint unescaped, only surrounded by single quotes. A
mountpoint containing one or more single quotes would cause the command
to fail or potentially execute arbitrary shell code.
This change also provides compatibility with grsecurity patches.
Grsecurity only allows call_usermodehelper() to use helper binaries in
certain paths. /usr/bin/* is allowed, /bin/* is not.
Linux 3.14 introduces inode->set_acl(). Normally, acl modification will come
from setxattr, which will handle by the acl xattr_handler, and we already
handles that well. However, nfsd will directly calls inode->set_acl or
return error if it doesn't exists.
Reviewed-by: Tim Chase <tim@chase2k.com>
Reviewed-by: Massimo Maggi <me@massimo-maggi.eu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes#5371Closes#5375
In torvalds/linux@31051c8 the inode_change_ok() function was
renamed setattr_prepare() and updated to take a dentry ratheri
than an inode. Update the code to call the setattr_prepare()
and add a wrapper function which call inode_change_ok() for
older kernels.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
In Linux 4.9, torvalds/linux@fd50eca, iops->{set,get,remove}xattr and
generic_{set,get,remove}xattr are removed. xattr operations will directly
go through sb->s_xattr.
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
In Linux 4.9, torvalds/linux@2773bf0, iops->rename() and iops->rename2() are
merged together into iops->rename(), it now wants flags.
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
We must not use d_add_ci if the dentry already has the real name. Otherwise,
d_add_ci()->d_alloc_parallel() will find itself on the lookup hash and wait
on itself causing deadlock.
Tested-by: satmandu
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes#5124Closes#5141Closes#5147Closes#5148
Linux kernel commit 723c038475b78 removed this field.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: DHE <git@dehacked.net>
Closes#5393
These operations are dir specific, there's no point putting them in
zpl_inode_operations which is for regular files.
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Silence the following warning when compiling with gcc 5.4.0.
Specifically gcc (Ubuntu 5.4.0-6ubuntu1~16.04.1) 5.4.0 20160609.
module/avl/avl.c: In function ‘avl_add’:
module/avl/avl.c:647:2: warning: ‘where’ may be used uninitialized
in this function [-Wmaybe-uninitialized]
avl_insert(tree, new_node, where);
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
As of gcc 6.1.1 20160621 (Red Hat 6.1.1-3) an array bounds warnings
is detected in the zdb the dump_object() function. The analysis is
correct but difficult to interpret because this is implemented as a
macro. Rework the ZDB_OT_NAME in to a function and remove the case
detected by gcc which is a side effect of the DMU_OT_IS_VALID() macro.
zdb.c: In function ‘dump_object’:
zdb.c:1931:288: error: array subscript is outside array bounds
[-Werror=array-bounds]
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Closes#4907
Commit 5f6d0b6 was originally added to gracefully handle block
pointers with a damaged logical size. However, it incorrectly
assumed that all passed arc_done_func_t could handle a NULL
arc_buf_t.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#4069Closes#4080
All users of bio->bi_rw have been replaced with compatibility wrappers.
This allows the kernel specific logic to be abstracted away, and for
each of the supported cases to be documented with the wrapper. The
updated interfaces are as follows:
* void blk_queue_set_write_cache(struct request_queue *, bool, bool)
* boolean_t bio_is_flush(struct bio *)
* boolean_t bio_is_fua(struct bio *)
* boolean_t bio_is_discard(struct bio *)
* boolean_t bio_is_secure_erase(struct bio *)
* VDEV_WRITE_FLUSH_FUA
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes#4951
The posix_acl_valid() function has been updated to require a
user namespace. Filesystem callers should normally provide the
user_ns from the super block associcated with the ACL; the
zpl_posix_acl_valid() wrapper has been added for this purpose.
See https://github.com/torvalds/linux/commit/0d4d717f for
complete details.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes#4922
New REQ_OP_* definitions have been introduced to separate the
WRITE, READ, and DISCARD operations from the flags. This included
changing the encoding of bi_rw. It places REQ_OP_* in high order
bits and other stuff in low order bits. This encoding is done
through the new helper function bio_set_op_attrs. For complete
details refer to:
https://github.com/torvalds/linux/commit/f215082https://github.com/torvalds/linux/commit/4e1b2d5
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#4892Closes#4899
The REQ_FLUSH flag was renamed REQ_PREFLUSH to avoid confusion with
REQ_OP_FLUSH. See https://github.com/torvalds/linux/commit/28a8f0d3
for complete details.
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #4892
Issue #4899
The rw argument has been removed from submit_bio/submit_bio_wait.
Callers are now expected to set bio->bi_rw instead of passing it
in. See https://github.com/torvalds/linux/commit/4e49ea4a for
complete details.
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #4892
Issue #4899
If the loop index i comes to (ZFS_GET_NCOLS - 1), the cbp->cb_columns[i + 1]
actually read the data of cbp->cb_colwidths[0], which means the array
subscript is above array bounds.
Luckily the cbp->cb_colwidths[0] is always 0 and it seems we haven't
looped enough times to exceed the array bounds so far, but it's really
a secluded risk someday.
Signed-off-by: GeLiXin <ge.lixin@zte.com.cn>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#5003
zfs_get_name() expects a parameter of type zfs_handle_t *zhp , but
gets an invalid parameter type of zfs_handle_t **zhp actually in
libzfs_dataset_cmp(), which may trigger a coredump if called.
libzfs_dataset_cmp() working normally so far, just because all the
callers only give datasets of type ZFS_TYPE_FILESYSTEM to it, we
compared their mountpoint and return, luckily.
Signed-off-by: GeLiXin <ge.lixin@zte.com.cn>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#4919
Import a raidz pool which has a vdev with a bad label, zpool status
shows the right state of the dev, but the wrong state of the pool.
The pool state should be DEGRADED, not ONLINE.
We examine the label in vdev_validate while in spa_load_impl, the bad
label can be detected but doesn't propagate its state to the parent.
There are other chances to propagate state in the following vdev_load
if we failed to load DTL, but our pool is raidz1 which can tolerate a
faulted disk. So we lost the last chance to correct the pool state.
Propagate the leaf vdev's state to parent if its label was corrupted,
as is done elsewhere in vdev_validate.
Signed-off-by: GeLiXin <ge.lixin@zte.com.cn>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Don Brady <don.brady@intel.com>
Closes#4948
Async writes triggered by a self-healing IO may be issued before the
pool finishes the process of initialization. This results in a NULL
dereference of `spa->spa_dsl_pool` in vdev_queue_max_async_writes().
George Wilson recommended addressing this issue by initializing the
passed `dsl_pool_t **` prior to dmu_objset_open_impl(). Since the
caller is passing the `spa->spa_dsl_pool` this has the effect of
ensuring it's initialized.
However, since this depends on the caller knowing they must pass
the `spa->spa_dsl_pool` an additional NULL check was added to
vdev_queue_max_async_writes(). This guards against any future
restructuring of the code which might result in dsl_pool_init()
being called differently.
Signed-off-by: GeLiXin <47034221@qq.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#4652
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Yuri Pankov <yuri.pankov@nexenta.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Calling dsl_dataset_name on a dataset with a 256 byte buffer is asking
for trouble. We should check every dataset on import, using a 1024 byte
buffer and checking each time to see if the dataset's new name is longer
than 256 bytes.
OpenZFS-issue: https://www.illumos.org/issues/6876
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/ca8674e
nvlist_pack() and nvlist_unpack are implemented recursively, which can
cause the stack to overflow with a deeply nested nvlist; i.e. an nvlist
which contains an nvlist, which contains an nvlist, which...
Unprivileged users can pass an nvlist to the kernel via certain ioctls
on /dev/zfs, which the kernel will unpack without additional permission
checking or validation. Therefore, an unprivileged user can cause the
kernel's stack to overflow and panic.
Ideally, these functions would be implemented non-recursively. As a
quick fix, this patch limits the depth of the recursion and returns an
error when attempting to pack and unpack a deeply-nested nvlist.
Signed-off-by: Adam Leventhal <ahl@delphix.com>
Signed-off-by: George Wilson <george.wilson@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: Prakash Surya <prakash.surya@delphix.com>
OpenZFS-issue: https://www.illumos.org/issues/7263
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/0511d6d
-
Dropping DBUF_HASH_MUTEX when walking the hash list is unsafe. The dbuf
can be freed at any time.
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#4846
In arc_buf_info(), the arc_buf_t may have no header. If not, don't try
to fetch the arc buffer stats and instead just zero them.
The null dereferences were observed while accessing the dbuf kstat with
awk on a system in which millions of small files were being created in
order to overflow the system's metadata limit.
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes#4837
When generation mismatch, it usually means the file pointed by the file handle
was deleted. We should return ESTALE to indicate this. We return ENOENT in
zfs_vget since zpl_fh_to_dentry will convert it to ESTALE.
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #4828
Allow accessing XATTR through export handle is a very bad idea. It
would allow user to write whatever they want in fields where they
otherwise could not.
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #4828
arc_prune_task uses a refcount to protect arc_prune_t, but it doesn't prevent
the underlying zsb from disappearing if there's a concurrent umount. We fix
this by force the caller of arc_remove_prune_callback to wait for
arc_prune_taskq to finish.
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#4687Closes#4690
Certain ioctl operations will call get_zfs_sb, which will holds an active
count on sb without checking whether it's active or not. This will result
in use-after-free. We fix this by using atomic_inc_not_zero to make sure
we got an active sb.
P1 P2
--- ---
deactivate_locked_super(): s_active = 0
zfs_sb_hold()
->get_zfs_sb(): s_active = 1
->zpl_kill_sb()
-->zpl_put_super()
--->zfs_umount()
---->zfs_sb_free(zsb)
zfs_sb_rele(zsb)
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
zp->z_xattr_parent will pin the parent. This will cause huge issue
when unlink a file with xattr. Because the unlinked file is pinned, it
will never get purged immediately. And because of that, the xattr
stuff will never be marked as unlinked. So the whole unlinked stuff
will stay there until shrink cache or umount.
This change partially reverts e89260a. This is safe because only the
zp->z_xattr_parent optimization is removed, zpl_xattr_security_init()
is still called from the zpl outside the inode lock.
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Issue #4359
Issue #3508
Issue #4413
Issue #4827
We need to set inode->i_nlink to zero so iput will purge it. Without this, it
will get purged during shrink cache or umount, which would likely result in
deadlock due to zfs_zget waiting forever on its children which are in the
dispose_list of the same thread.
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Issue #4359
Issue #3508
Issue #4413
Issue #4827
The ZIO_CHECKSUM_IS_ZERO macro was added in master commit:
37f8a88 Illumos 5746 - more checksumming in zfs send
That whole patch is not suitable for the release branch
but some other backported patches on that macro.
Signed-off-by: Ned Bass <bass6@llnl.gov>
Adds a module option which disables the hole_birth optimization
which has been responsible for several recent bugs, including
issue #4050.
Original-patch: https://gist.github.com/pcd1193182/2c0cd47211f3aee623958b4698836c48
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#4833
The following scenario can result in garbage in the dn_spill field.
The db->db_blkptr must be set to NULL when DNODE_FLAG_SPILL_BLKPTR
is clear to ensure the dn_spill field is cleared.
Current txg = A.
* A new spill buffer is created. Its dbuf is initialized with
db_blkptr = NULL and it's dirtied.
Current txg = B.
* The spill buffer is modified. It's marked as dirty in this txg.
* Additional changes make the spill buffer unnecessary because the
xattr fits into the bonus buffer, so it's removed. The dbuf is
undirtied in this txg, but it's still referenced and cannot be
destroyed.
Current txg = C.
* Starts syncing of txg A
* dbuf_sync_leaf() is called for the spill buffer. Since db_blkptr
is NULL, dbuf_check_blkptr() is called.
* The dbuf starts being written and it reaches the ready state
(not done yet).
* A new change makes the spill buffer necessary again.
sa_build_layouts() ends up calling dbuf_find() to locate the
dbuf. It finds the old dbuf because it has not been destroyed yet
(it will be destroyed when the previous write is done and there
are no more references). The old dbuf has db_blkptr != NULL.
* txg A write is complete and the dbuf released. However it's still
referenced, so it's not destroyed.
Current txg = D.
* Starts syncing of txg B
* dbuf_sync_leaf() is called for the bonus buffer. Its contents are
directly copied into the dnode, overwriting the blkptr area because,
in txg B, the bonus buffer was big enough to hold the entire xattr.
* At this point, the db_blkptr of the spill buffer used in txg C
gets corrupted.
Signed-off-by: Peng <peng.hse@xtaotech.com>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3937