OpenZFS 6410 - teach zdb to perform object lookups by path

Authored by: Yuri Pankov <[email protected]>
Reviewed by: Pavel Zakharov <[email protected]>
Reviewed by: Matthew Ahrens <[email protected]>
Reviewed by: Will Andrews <[email protected]>
Approved by: Dan McDonald <[email protected]>
Ported-by: Brian Behlendorf <[email protected]>

Porting Notes:
- Replaced zdb.8 with upstream mdoc zdb.1m version.  Updated to
  include Linux specific features: -V verbatium imports and
  improved label printing (-u, and -l).
- Minor changes to `zdb -h` output to honor 80 character limit.

OpenZFS-issue: https://www.illumos.org/issues/6410
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/ed61ec1
Closes #6006 

1 files changed, 326 insertions, 511 deletions

diff --git a/man/man8/zdb.8 b/man/man8/zdb.8
index 667f6b171..83e7fba14 100644
--- a/man/man8/zdb.8
+++ b/man/man8/zdb.8
@@ -1,4 +1,3 @@
-'\" t
 .\"
 .\" This file and its contents are supplied under the terms of the
 .\" Common Development and Distribution License ("CDDL"), version 1.0.
@@ -12,556 +11,378 @@
 .\"
 .\" Copyright 2012, Richard Lowe.
 .\" Copyright (c) 2012, 2016 by Delphix. All rights reserved.
-.\" Copyright 2016 Nexenta Systems, Inc.
+.\" Copyright 2017 Nexenta Systems, Inc.
+.\" Copyright (c) 2017 Lawrence Livermore National Security, LLC.
+.\" Copyright (c) 2017 Intel Corporation.
 .\"
-.TH "ZDB" "8" "April 9, 2016" "" ""
-
-.SH "NAME"
-\fBzdb\fR - Display zpool debugging and consistency information
-
-.SH "SYNOPSIS"
-\fBzdb\fR [-CumdibcsDvhLMXFPAG] [-e [-p \fIpath\fR...]] [-t \fItxg\fR]
-    [-U \fIcache\fR] [-I \fIinflight I/Os\fR] [-x \fIdumpdir\fR]
-    [-o \fIvar\fR=\fIvalue\fR] ... [\fIpoolname\fR [\fIobject\fR ...]]
-
-.P
-\fBzdb\fR [-divPA] [-e [-p \fIpath\fR...]] [-U \fIcache\fR]
-    \fIdataset\fR [\fIobject\fR ...]
-
-.P
-\fBzdb\fR -m [-MLXFPA] [-t \fItxg\fR] [-e [-p \fIpath\fR...]] [-U \fIcache\fR]
-    \fIpoolname\fR [\fIvdev\fR [\fImetaslab\fR ...]]
-
-.P
-\fBzdb\fR -R [-A] [-e [-p \fIpath\fR...]] [-U \fIcache\fR] \fIpoolname\fR
-    \fIvdev\fR:\fIoffset\fR:\fIsize\fR[:\fIflags\fR]
-
-.P
-\fBzdb\fR -S [-AP] [-e [-p \fIpath\fR...]] [-U \fIcache\fR] \fIpoolname\fR
-
-.P
-\fBzdb\fR -l [-Aqu] \fIdevice\fR
-
-.P
-\fBzdb\fR -C [-A] [-U \fIcache\fR]
-
-.SH "DESCRIPTION"
-The \fBzdb\fR utility displays information about a ZFS pool useful for
-debugging and performs some amount of consistency checking. It is a not a
-general purpose tool and options (and facilities) may change. This is neither
-a fsck(8) nor an fsdb(8) utility.
-
-.P
+.Dd April 11, 2017
+.Dt ZDB 8 SMM
+.Os Linux
+.Sh NAME
+.Nm zdb
+.Nd display zpool debugging and consistency information
+.Sh SYNOPSIS
+.Nm
+.Op Fl AbcdDFGhiLMPsvVX
+.Op Fl e Op Fl p Ar path ...
+.Op Fl I Ar inflight I/Os
+.Oo Fl o Ar var Ns = Ns Ar value Oc Ns ...
+.Op Fl t Ar txg
+.Op Fl U Ar cache
+.Op Fl x Ar dumpdir
+.Op Ar poolname Op Ar object ...
+.Nm
+.Op Fl AdiPv
+.Op Fl e Op Fl p Ar path ...
+.Op Fl U Ar cache
+.Ar dataset Op Ar object ...
+.Nm
+.Fl C
+.Op Fl A
+.Op Fl U Ar cache
+.Nm
+.Fl l
+.Op Fl Aqu
+.Ar device
+.Nm
+.Fl m
+.Op Fl AFLPVX
+.Op Fl t Ar txg
+.Op Fl e Op Fl p Ar path ...
+.Op Fl U Ar cache
+.Ar poolname Op Ar vdev Op Ar metaslab ...
+.Nm
+.Fl O
+.Ar dataset path
+.Nm
+.Fl R
+.Op Fl A
+.Op Fl e Op Fl p Ar path ...
+.Op Fl U Ar cache
+.Ar poolname vdev Ns : Ns Ar offset Ns : Ns Ar size Ns Op : Ns Ar flags
+.Nm
+.Fl S
+.Op Fl AP
+.Op Fl e Op Fl p Ar path ...
+.Op Fl U Ar cache
+.Ar poolname
+.Sh DESCRIPTION
+The
+.Nm
+utility displays information about a ZFS pool useful for debugging and performs
+some amount of consistency checking.
+It is a not a general purpose tool and options
+.Pq and facilities
+may change.
+This is neither a
+.Xr fsck 1M
+nor an
+.Xr fsdb 1M
+utility.
+.Pp
 The output of this command in general reflects the on-disk structure of a ZFS
-pool, and is inherently unstable. The precise output of most invocations is
-not documented, a knowledge of ZFS internals is assumed.
-
-.P
-If the \fIdataset\fR argument does not contain any \fB/\fR or \fB@\fR
-characters, it is interpreted as a pool name.  The root dataset can be
-specified as \fIpool\fB/\fR (pool name followed by a slash).
-
-.P
+pool, and is inherently unstable.
+The precise output of most invocations is not documented, a knowledge of ZFS
+internals is assumed.
+.Pp
+If the
+.Ar dataset
+argument does not contain any
+.Qq Sy /
+or
+.Qq Sy @
+characters, it is interpreted as a pool name.
+The root dataset can be specified as
+.Ar pool Ns /
+.Pq pool name followed by a slash .
+.Pp
 When operating on an imported and active pool it is possible, though unlikely,
 that zdb may interpret inconsistent pool data and behave erratically.
-
-.SH "OPTIONS"
+.Sh OPTIONS
 Display options:
-
-.sp
-.ne 2
-.na
-\fB-b\fR
-.ad
-.sp .6
-.RS 4n
-Display statistics regarding the number, size (logical, physical and
-allocated) and deduplication of blocks.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-c\fR
-.ad
-.sp .6
-.RS 4n
+.Bl -tag -width Ds
+.It Fl b
+Display statistics regarding the number, size
+.Pq logical, physical and allocated
+and deduplication of blocks.
+.It Fl c
 Verify the checksum of all metadata blocks while printing block statistics
-(see \fB-b\fR).
-.sp
+.Po see
+.Fl b
+.Pc .
+.Pp
 If specified multiple times, verify the checksums of all blocks.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-C\fR
-.ad
-.sp .6
-.RS 4n
-Display information about the configuration. If specified with no other
-options, instead display information about the cache file
-(\fB/etc/zfs/zpool.cache\fR). To specify the cache file to display, see
-\fB-U\fR.
-.P
-If specified multiple times, and a pool name is also specified display both
-the cached configuration and the on-disk configuration.  If specified multiple
-times with \fB-e\fR also display the configuration that would be used were the
-pool to be imported.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-d\fR
-.ad
-.sp .6
-.RS 4n
-Display information about datasets. Specified once, displays basic dataset
-information: ID, create transaction, size, and object count.
-.sp
+.It Fl C
+Display information about the configuration.
+If specified with no other options, instead display information about the cache
+file
+.Pq Pa /etc/zfs/zpool.cache .
+To specify the cache file to display, see
+.Fl U .
+.Pp
+If specified multiple times, and a pool name is also specified display both the
+cached configuration and the on-disk configuration.
+If specified multiple times with
+.Fl e
+also display the configuration that would be used were the pool to be imported.
+.It Fl d
+Display information about datasets.
+Specified once, displays basic dataset information: ID, create transaction,
+size, and object count.
+.Pp
 If specified multiple times provides greater and greater verbosity.
-.sp
-If object IDs are specified, display information about those specific objects only.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-D\fR
-.ad
-.sp .6
-.RS 4n
-Display deduplication statistics, including the deduplication ratio (dedup),
-compression ratio (compress), inflation due to the zfs copies property
-(copies), and an overall effective ratio (dedup * compress / copies).
-.sp
-If specified twice, display a histogram of deduplication statistics, showing
-the allocated (physically present on disk) and referenced (logically
-referenced in the pool) block counts and sizes by reference count.
-.sp
-If specified a third time, display the statistics independently for each deduplication table.
-.sp
-If specified a fourth time, dump the contents of the deduplication tables describing duplicate blocks.
-.sp
-If specified a fifth time, also dump the contents of the deduplication tables describing unique blocks.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-h\fR
-.ad
-.sp .6
-.RS 4n
-Display pool history similar to \fBzpool history\fR, but include internal
-changes, transaction, and dataset information.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-i\fR
-.ad
-.sp .6
-.RS 4n
-Display information about intent log (ZIL) entries relating to each
-dataset. If specified multiple times, display counts of each intent log
-transaction type.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-l\fR \fIdevice\fR
-.ad
-.sp .6
-.RS 4n
-Read the vdev labels from the specified device and dump the unique
-configuration nvlist(s). \fBzdb -l\fR will return 1 if an error occured, 2 if
-no configuration nvlist could be unpacked (errors or not), and 0 otherwise.
-Specify multiple times to increase verbosity.
-.P
-If the \fB-u\fR option is also specified, also display the uberblocks on this
-device.  Specify multiple times to increase verbosity.
-.P
-If the \fB-q\fR option is also specified, don't dump the configurations or the
-uberblocks.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-L\fR
-.ad
-.sp .6
-.RS 4n
-Disable leak tracing and the loading of space maps.  By default, \fBzdb\fR
+.Pp
+If object IDs are specified, display information about those specific objects
+only.
+.It Fl D
+Display deduplication statistics, including the deduplication ratio
+.Pq Sy dedup ,
+compression ratio
+.Pq Sy compress ,
+inflation due to the zfs copies property
+.Pq Sy copies ,
+and an overall effective ratio
+.Pq Sy dedup No * Sy compress No / Sy copies .
+.It Fl DD
+Display a histogram of deduplication statistics, showing the allocated
+.Pq physically present on disk
+and referenced
+.Pq logically referenced in the pool
+block counts and sizes by reference count.
+.It Fl DDD
+Display the statistics independently for each deduplication table.
+.It Fl DDDD
+Dump the contents of the deduplication tables describing duplicate blocks.
+.It Fl DDDDD
+Also dump the contents of the deduplication tables describing unique blocks.
+.It Fl h
+Display pool history similar to
+.Nm zpool Cm history ,
+but include internal changes, transaction, and dataset information.
+.It Fl i
+Display information about intent log
+.Pq ZIL
+entries relating to each dataset.
+If specified multiple times, display counts of each intent log transaction type.
+.It Fl l Ar device
+Read the vdev labels from the specified device.
+.Nm Fl l
+will return 0 if valid label was found, 1 if error occurred, and 2 if no valid
+labels were found. Each unique configuration is displayed only once.
+.It Fl ll Ar device
+In addition display label space usage stats.
+.It Fl lll Ar device
+Display every configuration, unique or not.
+.Pp
+If the
+.Fl q
+option is also specified, don't print the labels.
+.Pp
+If the
+.Fl u
+option is also specified, also display the uberblocks on this device.  Specify
+multiple times to increase verbosity.
+.It Fl L
+Disable leak tracing and the loading of space maps.
+By default,
+.Nm
 verifies that all non-free blocks are referenced, which can be very expensive.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-m\fR
-.ad
-.sp .6
-.RS 4n
+.It Fl m
 Display the offset, spacemap, and free space of each metaslab.
-When specified twice, also display information about the on-disk free
-space histogram associated with each metaslab. When specified three time,
-display the maximum contiguous free space, the in-core free space histogram,
-and the percentage of free space in each space map.  When specified
-four times display every spacemap record.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-M\fR
-.ad
-.sp .6
-.RS 4n
+.It Fl mm
+Also display information about the on-disk free space histogram associated with
+each metaslab.
+.It Fl mmm
+Display the maximum contiguous free space, the in-core free space histogram, and
+the percentage of free space in each space map.
+.It Fl mmmm
+Display every spacemap record.
+.It Fl M
 Display the offset, spacemap, and free space of each metaslab.
-When specified twice, also display information about the maximum contiguous
-free space and the percentage of free space in each space map.  When specified
-three times display every spacemap record.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-R\fR \fIpoolname\fR \fIvdev\fR:\fIoffset\fR:\fIsize\fR[:\fIflags\fR]
-.ad
-.sp .6
-.RS 4n
-Read and display a block from the specified device. By default the block is
-displayed as a hex dump, but see the description of the \'r\' flag, below.
-.sp
-The block is specified in terms of a colon-separated tuple \fIvdev\fR (an
-integer vdev identifier) \fIoffset\fR (the offset within the vdev) \fIsize\fR
-(the size of the block to read) and, optionally, \fIflags\fR (a set of flags,
-described below).
-
-.sp
-.ne 2
-.na
-\fBb\fR \fIoffset\fR
-.ad
-.sp .6
-.RS 4n
+.It Fl MM
+Also display information about the maximum contiguous free space and the
+percentage of free space in each space map.
+.It Fl MMM
+Display every spacemap record.
+.It Fl O Ar dataset path
+Look up the specified
+.Ar path
+inside of the
+.Ar dataset
+and display its metadata and indirect blocks.
+Specified
+.Ar path
+must be relative to the root of
+.Ar dataset .
+This option can be combined with
+.Fl v
+for increasing verbosity.
+.It Fl R Ar poolname vdev Ns : Ns Ar offset Ns : Ns Ar size Ns Op : Ns Ar flags
+Read and display a block from the specified device.
+By default the block is displayed as a hex dump, but see the description of the
+.Sy r
+flag, below.
+.Pp
+The block is specified in terms of a colon-separated tuple
+.Ar vdev
+.Pq an integer vdev identifier
+.Ar offset
+.Pq the offset within the vdev
+.Ar size
+.Pq the size of the block to read
+and, optionally,
+.Ar flags
+.Pq a set of flags, described below .
+.Pp
+.Bl -tag -compact -width "b offset"
+.It Sy b Ar offset
 Print block pointer
-.RE
-
-.sp
-.ne 2
-.na
-\fBd\fR
-.ad
-.sp .6
-.RS 4n
+.It Sy d
 Decompress the block
-.RE
-
-.sp
-.ne 2
-.na
-\fBe\fR
-.ad
-.sp .6
-.RS 4n
+.It Sy e
 Byte swap the block
-.RE
-
-.sp
-.ne 2
-.na
-\fBg\fR
-.ad
-.sp .6
-.RS 4n
+.It Sy g
 Dump gang block header
-.RE
-
-.sp
-.ne 2
-.na
-\fBi\fR
-.ad
-.sp .6
-.RS 4n
+.It Sy i
 Dump indirect block
-.RE
-
-.sp
-.ne 2
-.na
-\fBr\fR
-.ad
-.sp .6
-.RS 4n
+.It Sy r
 Dump raw uninterpreted block data
-.RE
-.RE
-
-.sp
-.ne 2
-.na
-\fB-s\fR
-.ad
-.sp .6
-.RS 4n
-Report statistics on \fBzdb\fR\'s I/O. Display operation counts, bandwidth,
-and error counts of I/O to the pool from \fBzdb\fR.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-S\fR
-.ad
-.sp .6
-.RS 4n
+.El
+.It Fl s
+Report statistics on
+.Nm zdb
+I/O.
+Display operation counts, bandwidth, and error counts of I/O to the pool from
+.Nm .
+.It Fl S
 Simulate the effects of deduplication, constructing a DDT and then display
-that DDT as with \fB-DD\fR.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-u\fR
-.ad
-.sp .6
-.RS 4n
+that DDT as with
+.Fl DD .
+.It Fl u
 Display the current uberblock.
-.RE
-
-.P
+.El
+.Pp
 Other options:
-
-.sp
-.ne 2
-.na
-\fB-A\fR
-.ad
-.sp .6
-.RS 4n
+.Bl -tag -width Ds
+.It Fl A
 Do not abort should any assertion fail.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-AA\fR
-.ad
-.sp .6
-.RS 4n
+.It Fl AA
 Enable panic recovery, certain errors which would otherwise be fatal are
 demoted to warnings.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-AAA\fR
-.ad
-.sp .6
-.RS 4n
+.It Fl AAA
 Do not abort if asserts fail and also enable panic recovery.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-e\fR [-p \fIpath\fR]...
-.ad
-.sp .6
-.RS 4n
-Operate on an exported pool, not present in \fB/etc/zfs/zpool.cache\fR. The
-\fB-p\fR flag specifies the path under which devices are to be searched.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-x\fR \fIdumpdir\fR
-.ad
-.sp .6
-.RS 4n
+.It Fl e Op Fl p Ar path ...
+Operate on an exported pool, not present in
+.Pa /etc/zfs/zpool.cache .
+The
+.Fl p
+flag specifies the path under which devices are to be searched.
+.It Fl x Ar dumpdir
 All blocks accessed will be copied to files in the specified directory.
 The blocks will be placed in sparse files whose name is the same as
-that of the file or device read.  zdb can be then run on the generated files.
-Note that the \fB-bbc\fR flags are sufficient to access (and thus copy)
+that of the file or device read.
+.Nm
+can be then run on the generated files.
+Note that the
+.Fl bbc
+flags are sufficient to access
+.Pq and thus copy
 all metadata on the pool.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-F\fR
-.ad
-.sp .6
-.RS 4n
+.It Fl F
 Attempt to make an unreadable pool readable by trying progressively older
 transactions.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-G\fR
-.ad
-.sp .6
-.RS 4n
-Dump the contents of the zfs_dbgmsg buffer before exiting zdb. zfs_dbgmsg is
-a buffer used by ZFS to dump advanced debug information.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-I \fIinflight I/Os\fR \fR
-.ad
-.sp .6
-.RS 4n
-Limit the number of outstanding checksum I/Os to the specified value. The
-default value is 200. This option affects the performance of the \fB-c\fR
+.It Fl G
+Dump the contents of the zfs_dbgmsg buffer before exiting
+.Nm .
+zfs_dbgmsg is a buffer used by ZFS to dump advanced debug information.
+.It Fl I Ar inflight I/Os
+Limit the number of outstanding checksum I/Os to the specified value.
+The default value is 200.
+This option affects the performance of the
+.Fl c
 option.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-o \fIvar\fR=\fIvalue\fR ... \fR
-.ad
-.sp .6
-.RS 4n
-Set the given global libzpool variable to the provided value. The value must
-be an unsigned 32-bit integer. Currently only little-endian systems are
-supported to avoid accidentally setting the high 32 bits of 64-bit variables.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-P\fR
-.ad
-.sp .6
-.RS 4n
+.It Fl o Ar var Ns = Ns Ar value ...
+Set the given global libzpool variable to the provided value.
+The value must be an unsigned 32-bit integer.
+Currently only little-endian systems are supported to avoid accidentally setting
+the high 32 bits of 64-bit variables.
+.It Fl P
 Print numbers in an unscaled form more amenable to parsing, eg. 1000000 rather
 than 1M.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-t\fR \fItransaction\fR
-.ad
-.sp .6
-.RS 4n
-Specify the highest transaction to use when searching for uberblocks. See also
-the \fB-u\fR and \fB-l\fR options for a means to see the available uberblocks
-and their associated transaction numbers.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-U\fR \fIcachefile\fR
-.ad
-.sp .6
-.RS 4n
-Use a cache file other than \fB/etc/zfs/zpool.cache\fR.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-v\fR
-.ad
-.sp .6
-.RS 4n
-Enable verbosity. Specify multiple times for increased verbosity.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-X\fR
-.ad
-.sp .6
-.RS 4n
-Attempt \'extreme\' transaction rewind, that is attempt the same recovery as
-\fB-F\fR but read transactions otherwise deemed too old.
-.RE
-
-.sp
-.ne 2
-.na
-\fB-V\fR
-.ad
-.sp .6
-.RS 4n
-Attempt a verbatim import. This mimics the behavior of the kernel when loading
-a pool from a cachefile.
-.RE
-
-.P
+.It Fl t Ar transaction
+Specify the highest transaction to use when searching for uberblocks.
+See also the
+.Fl u
+and
+.Fl l
+options for a means to see the available uberblocks and their associated
+transaction numbers.
+.It Fl U Ar cachefile
+Use a cache file other than
+.Pa /etc/zfs/zpool.cache .
+.It Fl v
+Enable verbosity.
+Specify multiple times for increased verbosity.
+.It Fl V
+Attempt a verbatim import. This mimics the behavior of the kernel when
+loading a pool from a cachefile.
+.It Fl X
+Attempt
+.Qq extreme
+transaction rewind, that is attempt the same recovery as
+.Fl F
+but read transactions otherwise deemed too old.
+.El
+.Pp
 Specifying a display option more than once enables verbosity for only that
 option, with more occurrences enabling more verbosity.
-.P
+.Pp
 If no options are specified, all information about the named pool will be
 displayed at default verbosity.
-
-.SH "EXAMPLES"
-.LP
-\fBExample 1 \fRDisplay the configuration of imported pool 'rpool'
-.sp
-.in +2
-.nf
+.Sh EXAMPLES
+.Bl -tag -width Ds
+.It Xo
+.Sy Example 1
+Display the configuration of imported pool
+.Pa rpool
+.Xc
+.Bd -literal
 # zdb -C rpool
 
 MOS Configuration:
         version: 28
         name: 'rpool'
  ...
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 2 \fRDisplay basic dataset information about 'rpool'
-.sp
-.in +2
-.nf
+.Ed
+.It Xo
+.Sy Example 2
+Display basic dataset information about
+.Pa rpool
+.Xc
+.Bd -literal
 # zdb -d rpool
 Dataset mos [META], ID 0, cr_txg 4, 26.9M, 1051 objects
 Dataset rpool/swap [ZVOL], ID 59, cr_txg 356, 486M, 2 objects
  ...
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 3 \fRDisplay basic information about object 0
-in 'rpool/export/home'
-.sp
-.in +2
-.nf
+.Ed
+.It Xo
+.Sy Example 3
+Display basic information about object 0 in
+.Pa rpool/export/home
+.Xc
+.Bd -literal
 # zdb -d rpool/export/home 0
 Dataset rpool/export/home [ZPL], ID 137, cr_txg 1546, 32K, 8 objects
 
     Object  lvl   iblk   dblk  dsize  lsize   %full  type
          0    7    16K    16K  15.0K    16K   25.00  DMU dnode
-.fi
-.in -2
-.sp
-
-.LP
-\fBExample 4 \fRDisplay the predicted effect of enabling deduplication on 'rpool'
-.sp
-.in +2
-.nf
+.Ed
+.It Xo
+.Sy Example 4
+Display the predicted effect of enabling deduplication on
+.Pa rpool
+.Xc
+.Bd -literal
 # zdb -S rpool
 Simulated DDT histogram:
 
@@ -573,14 +394,8 @@ refcnt   blocks   LSIZE   PSIZE   DSIZE   blocks   LSIZE   PSIZE   DSIZE
      2    35.0K   1.33G    699M    699M    74.7K   2.79G   1.45G   1.45G
  ...
 dedup = 1.11, compress = 1.80, copies = 1.00, dedup * compress / copies = 2.00
-.fi
-.in -2
-.sp
-
-.SH "ENVIRONMENT VARIABLES"
-.TP
-.B "SPA_CONFIG_PATH"
-Override the default \fBspa_config_path\fR (\fI/etc/zfs/zpool.cache\fR) setting. If \fB-U\fR flag is specified it will override this environment variable settings once again.
-
-.SH "SEE ALSO"
-zfs(8), zpool(8)
+.Ed
+.El
+.Sh SEE ALSO
+.Xr zfs 8 ,
+.Xr zpool 8