The ICP requires destructors to for each crypto module that is added.
These do not necessarily exist in Illumos because they assume that
these modules can never be unloaded from the kernel. Some of this
cleanup code was missed when #4760 was merged, resulting in leaks.
This patch simply fixes that.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Issue #4760Closes#5265
Fix use after free in zfsctl_snapshot_unmount(). Use /usr/bin/env
instead of /bin/sh to fix a shell code injection flaw and allow use
with grsecurity.
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Stian Ellingsen <stian@plaimi.net>
Closes#5250Closes#4377
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
When #4760 was merged tests were added to ensure that the new checksums
were working properly. However, some of the functionality for sha2
functions were not ported over, resulting in some Coverity defects and
code that would be unstable when needed in the future. This patch
simply ports over the missing code and fixes the defects in the
process.
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Issue #4760Closes#5251
The following new test cases need to have execute permissions set:
userquota/groupspace_003_pos.ksh
userquota/userquota_013_pos.ksh
userquota/userspace_003_pos.ksh
upgrade/upgrade_userobj_001_pos.ksh
upgrade/setup.ksh
upgrade/cleanup.ksh
The following source files accidentally were marked executable:
lib/libzpool/kernel.c
lib/libshare/nfs.c
lib/libzfs/libzfs_dataset.c
lib/libzfs/libzfs_util.c
tests/zfs-tests/cmd/rm_lnkcnt_zero_file/rm_lnkcnt_zero_file.c
tests/zfs-tests/cmd/dir_rd_update/dir_rd_update.c
cmd/zed/zed_exec.c
module/icp/core/kcf_sched.c
module/zfs/dsl_pool.c
module/zfs/arc.c
module/nvpair/nvpair.c
man/man5/zfs-module-parameters.5
Reviewed-by: GeLiXin <ge.lixin@zte.com.cn>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#5241
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.
OpenZFS decided that ignore_hole_birth was too imprecise and
incorrect a name (and went with send_holes_without_birth_time).
Rename it in ZoL too, while keeping the name "ignore_hole_birth"
pointing to the same variable for existing consumers.
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes#5239
Updating vd->vdev_parent->vdev_nonrot in vdev_open_child()
is a race when vdev_open_child is called for many children
from a task queue.
vdev_open_child() is only called by vdev_open_children(), let
the latter update the parent vdev_nonrot member. The update
was already there, so done twice previously. Thus using the
same logic at the end in vdev_open_children() to update
vdev_nonrot, either we are vdev_uses_zvols() or not.
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Haakan T Johansson <f96hajo@chalmers.se>
Closes#5162
Fixes ABI issues with fletcher4 code, adds support for
incremental updates, and adds ztest method for testing.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Closes#5164
Using a benchmark which creates 2 million files in one TXG, I observe
that the thread running spa_sync() is on CPU almost the entire time we
are syncing, and therefore can be a performance bottleneck. About 50% of
the time in spa_sync() is in dmu_objset_do_userquota_updates().
The problem is that dmu_objset_do_userquota_updates() calls
zap_increment_int(DMU_USERUSED_OBJECT) once for every file that was
modified (or created). In this benchmark, all the files are owned by the
same user/group, so all 2 million calls to zap_increment_int() are
modifying the same entry in the zap. The same issue exists for the
DMU_GROUPUSED_OBJECT.
We should keep an in-memory map from user to space delta while we are
syncing, and when we finish, iterate over the in-memory map and modify
the ZAP once per entry. This reduces the number of calls to
zap_increment_int() from "number of objects modified" to "number of
owners/groups of modified files".
This reduced the time spent in spa_sync() in the file create benchmark
by ~33%, from 11 seconds to 7 seconds.
Upstream bugs: DLPX-44799
Ported by: Ned Bass <bass6@llnl.gov>
OpenZFS-issue: https://www.illumos.org/issues/6988
ZFSonLinux-issue: https://github.com/zfsonlinux/zfs/issues/4642
OpenZFS-commit: unmerged
Porting notes:
- Added curly braces around declaration of userquota_cache_t cache to
quiet compiler warning;
- Handled the userobj accounting the same way it proposed in this path.
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
This patch tracks dnode usage for each user/group in the
DMU_USER/GROUPUSED_OBJECT ZAPs. ZAP entries dedicated to dnode
accounting have the key prefixed with "obj-" followed by the UID/GID
in string format (as done for the block accounting).
A new SPA feature has been added for dnode accounting as well as
a new ZPL version. The SPA feature must be enabled in the pool
before upgrading the zfs filesystem. During the zfs version upgrade,
a "quotacheck" will be executed by marking all dnode as dirty.
ZoL-bug-id: https://github.com/zfsonlinux/zfs/issues/3500
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Signed-off-by: Johann Lombardi <johann.lombardi@intel.com>
Move the synchronization of inode/znode i_flgas/pflags into
the respective internal zfs function. This is mostly
mechanical work and shouldn't introduce any functional
changes.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com>
Issue #227Closes#5223
Init, compute, and fini methods are changed to work on internal context object.
This is necessary because ABI does not guarantee that SIMD registers will be preserved
on function calls. This is technically the case in Linux kernel in between
`kfpu_begin()/kfpu_end()`, but it breaks user-space tests and some kernels that
don't require disabling preemption for using SIMD (osx).
Use scalar compute methods in-place for small buffers, and when the buffer size
does not meet SIMD size alignment.
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Combine incrementally computed fletcher4 checksums. Checksums are combined
a posteriori, allowing for parallel computation on chunks to be implemented if
required. The algorithm is general, and does not add changes in each SIMD
implementation.
New test in ztest verifies incremental fletcher computations.
Checksum combining matrix for two buffers `a` and `b`, where `Ca` and `Cb` are
respective fletcher4 checksums, `Cab` is combined checksum, `s` is size of buffer
`b` (divided by sizeof(uint32_t)) is:
Cab[A] = Cb[A] + Ca[A]
Cab[B] = Cb[B] + Ca[B] + s * Ca[A]
Cab[C] = Cb[C] + Ca[C] + s * Ca[B] + s(s+1)/2 * Ca[A]
Cab[D] = Cb[D] + Ca[D] + s * Ca[C] + s(s+1)/2 * Ca[B] + s(s+1)(s+2)/6 * Ca[A]
NOTE: this calculation overflows for larger buffers. Thus, internally, the calculation
is performed on 8MiB chunks.
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Authored by: ilovezfs <ilovezfs@icloud.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Richard Laager <rlaager@wiktel.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Ported by: Tony Hutter <hutter2@llnl.gov>
In any pool without the extensible dataset feature flag already enabled,
creating a dataset with dedup set to use one of the new checksums would
result in the following panic as soon as any data was added:
panic[cpu0]/thread=ffffff0006761c40: feature_get_refcount(spa, feature,
&refcount) != 48 (0x30 != 0x30), file: ../../common/fs/zfs/zfeature.c
line 390
Inpsection showed that feature->fi_feature was 7, which is the value of
SPA_FEATURE_EXTENSIBLE_DATASET in the spa_feature enum. This commit
adds extensible dataset as a dependency for the sha512, edonr, and skein
feature flags, which prevents the panic.
OpenZFS-issue: https://www.illumos.org/issues/6585
OpenZFS-commit: 892586e8a1
Porting Notes:
This code was originally from Illumos, but I actually ported it from:
openzfsonosx/zfs@b62a652
Authored by: ilovezfs <ilovezfs@icloud.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Richard Laager <rlaager@wiktel.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Ported-by: Tony Hutter <hutter2@llnl.gov>
zio_checksum_to_feature() expects a zio_checksum enum not a raw property
intval, so the new checksums weren't being detected when the
ZIO_CHECKSUM_VERIFY flag got in the way.
Given a pool without feature@sha512,
zfs create -o dedup=sha512 naughty/fivetwelve_noverify_ds
would fail as expected since the raw intval would indeed be equal to
SPA_FEATURE_SHA512.
However,
zfs create -o dedup=sha512,verify naughty/fivetwelve_verify_ds
would incorrectly succeed because ZIO_CHECKSUM_VERIFY would be in the
way, the raw intval would not be a member of the enum, and
zio_checksum_to_feature() would return SPA_FEATURE_NONE, with the result
that spa_feature_is_enabled() would never be called.
This was first detected with edonr, since in that case verify is
required.
This commit clears the ZIO_CHECKSUM_VERIFY flag before calling
zio_checksum_to_feature() using the ZIO_CHECKSUM_MASK and verifies in
zio_checksum_to_feature() that ZIO_CHECKSUM_MASK has been applied by the
caller to attempt to prevent the same bug from occurring again in the
future.
OpenZFS-issue: https://www.illumos.org/issues/6541
OpenZFS-commit: 971640e6aa
Porting notes:
This code was originally from Illumos, but I actually ported it from:
openzfsonosx/zfs@bef06e1
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Saso Kiselkov <saso.kiselkov@nexenta.com>
Reviewed by: Richard Lowe <richlowe@richlowe.net>
Approved by: Garrett D'Amore <garrett@damore.org>
Ported by: Tony Hutter <hutter2@llnl.gov>
OpenZFS-issue: https://www.illumos.org/issues/4185
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/45818ee
Porting Notes:
This code is ported on top of the Illumos Crypto Framework code:
b5e030c8db
The list of porting changes includes:
- Copied module/icp/include/sha2/sha2.h directly from illumos
- Removed from module/icp/algs/sha2/sha2.c:
#pragma inline(SHA256Init, SHA384Init, SHA512Init)
- Added 'ctx' to lib/libzfs/libzfs_sendrecv.c:zio_checksum_SHA256() since
it now takes in an extra parameter.
- Added CTASSERT() to assert.h from for module/zfs/edonr_zfs.c
- Added skein & edonr to libicp/Makefile.am
- Added sha512.S. It was generated from sha512-x86_64.pl in Illumos.
- Updated ztest.c with new fletcher_4_*() args; used NULL for new CTX argument.
- In icp/algs/edonr/edonr_byteorder.h, Removed the #if defined(__linux) section
to not #include the non-existant endian.h.
- In skein_test.c, renane NULL to 0 in "no test vector" array entries to get
around a compiler warning.
- Fixup test files:
- Rename <sys/varargs.h> -> <varargs.h>, <strings.h> -> <string.h>,
- Remove <note.h> and define NOTE() as NOP.
- Define u_longlong_t
- Rename "#!/usr/bin/ksh" -> "#!/bin/ksh -p"
- Rename NULL to 0 in "no test vector" array entries to get around a
compiler warning.
- Remove "for isa in $($ISAINFO); do" stuff
- Add/update Makefiles
- Add some userspace headers like stdio.h/stdlib.h in places of
sys/types.h.
- EXPORT_SYMBOL *_Init/*_Update/*_Final... routines in ICP modules.
- Update scripts/zfs2zol-patch.sed
- include <sys/sha2.h> in sha2_impl.h
- Add sha2.h to include/sys/Makefile.am
- Add skein and edonr dirs to icp Makefile
- Add new checksums to zpool_get.cfg
- Move checksum switch block from zfs_secpolicy_setprop() to
zfs_check_settable()
- Fix -Wuninitialized error in edonr_byteorder.h on PPC
- Fix stack frame size errors on ARM32
- Don't unroll loops in Skein on 32-bit to save stack space
- Add memory barriers in sha2.c on 32-bit to save stack space
- Add filetest_001_pos.ksh checksum sanity test
- Add option to write psudorandom data in file_write utility
This re-use the framework established for SSE2, SSSE3 and
AVX2. However, GCC is using FP registers on Aarch64, so
unlike SSE/AVX2 we can't rely on the registers being left alone
between ASM statements. So instead, the NEON code uses
C variables and GCC extended ASM syntax. Note that since
the kernel explicitly disable vector registers, they
have to be locally re-enabled explicitly.
As we use the variable's number to define the symbolic
name, and GCC won't allow duplicate symbolic names,
numbers have to be unique. Even when the code is not
going to be used (e.g. the case for 4 registers when
using the macro with only 2). Only the actually used
variables should be declared, otherwise the build
will fails in debug mode.
This requires the replacement of the XOR(X,X) syntax
by a new ZERO(X) macro, which does the same thing but
without repeating the argument. And perhaps someday
there will be a machine where there is a more efficient
way to zero a register than XOR with itself. This affects
scalar, SSE2, SSSE3 and AVX2 as they need the new macro.
It's possible to write faster implementations (different
scheduling, different unrolling, interleaving NEON and
scalar, ...) for various cores, but this one has the
advantage of fitting in the current state of the code,
and thus is likely easier to review/check/merge.
The only difference between aarch64-neon and aarch64-neonx2
is that aarch64-neonx2 unroll some functions some more.
Reviewed-by: Gvozden Neskovic <neskovic@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Romain Dolbeau <romain.dolbeau@atos.net>
Closes#4801
In the default case the function must return to avoid dereferencing
'prov_mech' which will be NULL.
Reviewed-by: Tom Caputi <tcaputi@datto.com>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: candychencan <chen.can2@zte.com.cn>
Closes#5134
coverity scan CID:147531,type: Argument cannot be negative
- may copy data with negative size
coverity scan CID:147532,type: resource leaks
- may close a fd which is negative
coverity scan CID:147533,type: resource leaks
- may call pwrite64 with a negative size
coverity scan CID:147535,type: resource leaks
- may call fdopen with a negative fd
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: GeLiXin <ge.lixin@zte.com.cn>
Closes#5176
Cppcheck 1.63 erroneously complains about an uninitialized value
in buf_init(). Newer versions of cppcheck (1.72) handle this
correctly but we'll initialize the value anyway to silence the
warning.
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#5203
Avoid calculating (1<<64) if lh_prefix_len == 0. Semantics of the method remain
the same.
Assert (lh_prefix_len > 0) in zap_expand_leaf() to detect possibly the same
problem.
Issue #4883
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Explicitly promote variables to correct type. Undefined behavior is
reported because length of int is not well defined by C standard.
Issue #4883
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Undefined operation is reported by running ztest (or zloop) compiled with GCC
UndefinedBehaviorSanitizer. Error only happens on top level of dnode indirection
with large enough offset values. Logically, left shift operation would work,
but bit shift semantics in C, and limitation of uint64_t, do not produce desired
result.
Issue #5059, #4883
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Without plugging, the default 'noop' scheduler will not merge
the BIOs which are part of a large ZIO.
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Isaac Huang <he.huang@intel.com>
Closes#5181
Refactor the code in such a way so that inode->i_mode is being set
at the same time zp->z_mode is being changed. This has the effect of
keeping both in sync without relying on zfs_inode_update.
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com>
Closes#5158
In arc_state_fini() the `arc_l2c_only->arcs_list[*]` multilists
must be destroyed. This accidentally regressed in d3c2ae1c.
Reviewed by: Tom Caputi <tcaputi@datto.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #5151Closes#5152
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
coverity scan CID:147633,type: sizeof not portable
coverity scan CID:147637,type: sizeof not portable
coverity scan CID:147638,type: sizeof not portable
coverity scan CID:147640,type: sizeof not portable
In these particular cases sizeof (XX **) happens to be equal to sizeof (X *),
but this is not a portable assumption.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: luozhengzheng <luo.zhengzheng@zte.com.cn>
Closes#5144
dbuf_read_impl() returns (SET_ERROR(err)) when err can be 0, which adds
lots of noise in tracing logs.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Isaac Huang <he.huang@intel.com>
Closes#4430Closes#5146
The type of "adjustmnt" was erroneously changed to unsigned when the compressed
ARC code was ported in d3c2ae1c08.
As a result of it being unsigned, the balanced metadata eviction logic
would evict all of the non-metadata.
Reviewed-by: Chris Severance <github.severach@spamgourmet.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: David Quigley <david.quigley@intel.com>
Signed-off-by: Tim Chase <tim@onlight.com>
Closes#5128Closes#5129
Enable ignore_hole_birth by default until all known hole birth bugs
have been resolved and relevant test cases added.
Reviewed-by: Boris Protopopov <boris.protopopov@actifio.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #4809Closes#5099
Simplify time handling in zfs_setattr by mimicking the logic in
setattr_copy from the linux kernel. In order to achieve this
in the case when ZFS' log is being replayed it is necessary
to unconditionally set the ctime in zfs_replay_setattr.
Also use the timespec_trunc function when assigning values to the
generic inode struct. This is currently a noop since zfs sets
s_time_gran to 1, however in the future rules about precision might
change.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com>
Closes#4916
ZFS doesn't provide a custom update_time method meaning it delegates
this job to the generic VFS layer. The only time when it needs to
set the various *time values is when the inode is being marshalled
to/from the disk. Do this by moving the relevant code from
zfs_inode_update_impl to zfs_node_alloc and zfs_rezget. As a result
from this change it is no longer necessary to have multiple versions
of the zfs_inode_update function - so just nuke them and leave only
one.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com>
Issue #227Closes#4916
Authored by: George Wilson <george.wilson@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Tom Caputi <tcaputi@datto.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported by: David Quigley <david.quigley@intel.com>
This review covers the reading and writing of compressed arc headers, sharing
data between the arc_hdr_t and the arc_buf_t, and the implementation of a new
dbuf cache to keep frequently access data uncompressed.
I've added a new member to l1 arc hdr called b_pdata. The b_pdata always hangs
off the arc_buf_hdr_t (if an L1 hdr is in use) and points to the physical block
for that DVA. The physical block may or may not be compressed. If compressed
arc is enabled and the block on-disk is compressed, then the b_pdata will match
the block on-disk and remain compressed in memory. If the block on disk is not
compressed, then neither will the b_pdata. Lastly, if compressed arc is
disabled, then b_pdata will always be an uncompressed version of the on-disk
block.
Typically the arc will cache only the arc_buf_hdr_t and will aggressively evict
any arc_buf_t's that are no longer referenced. This means that the arc will
primarily have compressed blocks as the arc_buf_t's are considered overhead and
are always uncompressed. When a consumer reads a block we first look to see if
the arc_buf_hdr_t is cached. If the hdr is cached then we allocate a new
arc_buf_t and decompress the b_pdata contents into the arc_buf_t's b_data. If
the hdr already has a arc_buf_t, then we will allocate an additional arc_buf_t
and bcopy the uncompressed contents from the first arc_buf_t to the new one.
Writing to the compressed arc requires that we first discard the b_pdata since
the physical block is about to be rewritten. The new data contents will be
passed in via an arc_buf_t (uncompressed) and during the I/O pipeline stages we
will copy the physical block contents to a newly allocated b_pdata.
When an l2arc is inuse it will also take advantage of the b_pdata. Now the
l2arc will always write the contents of b_pdata to the l2arc. This means that
when compressed arc is enabled that the l2arc blocks are identical to those
stored in the main data pool. This provides a significant advantage since we
can leverage the bp's checksum when reading from the l2arc to determine if the
contents are valid. If the compressed arc is disabled, then we must first
transform the read block to look like the physical block in the main data pool
before comparing the checksum and determining it's valid.
OpenZFS-issue: https://www.illumos.org/issues/6950
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7fc10f0
Issue #5078
