btrfs-progs: docs: fix warnings and links to duplicated labels

Use the new docref and duplabel syntax to fix build warnings and fix the
link targets in the pages.

[ci skip]

Signed-off-by: David Sterba <dsterba@suse.com>

Documentation/Status.rst

@@ -59,7 +59,7 @@ in following ways:
      - :statusmok:`mostly OK`
      -
      - extents get unshared (see below)
-   * - :ref:`Autodefrag<mount-option-autodefrag>`
+   * - :docref:`Autodefrag <Administration:mount-option-autodefrag>`
      - :statusok:`OK`
      -
      -
@@ -99,7 +99,7 @@ in following ways:
      - :statusmok:`mostly OK`
      - mostly OK
      -
-   * - :ref:`Degraded mount<mount-option-degraded>`
+   * - :docref:`Degraded mount <Administration:mount-option-degraded>`
      - :statusok:`OK`
      - n/a
      -

Documentation/btrfs-device.rst

@@ -48,7 +48,7 @@ remove [options] <device>|<devid> [<device>|<devid>...] <path>
         fails and cannot be enforced. The filesystem must be converted to
         profile(s) that would allow the removal. This can for example happen when
         going down from 2 devices to 1 and using the RAID1 profile. See the
-        section :ref:`Typical use cases<man-device-typical-use-cases>`.
+        section :docref:`Typical use cases <btrfs-device:man-device-typical-use-cases>`.
 
         The operation can take long as it needs to move all data from the device.
 
@@ -112,7 +112,8 @@ scan [options] [<device> [<device>...]]
         The command can be run repeatedly. Devices that have been already registered
         remain as such. Reloading the kernel module will drop this information. There's
         an alternative way of mounting multiple-device filesystem without the need for
-        prior scanning. See the mount option :ref:`device<mount-option-device>`.
+        prior scanning. See the mount option
+        :docref:`device <btrfs-man5:mount-option-device>`.
 
         ``Options``
 

Documentation/btrfs-scrub.rst

@@ -104,7 +104,7 @@ start [-BdrRf] <path>|<device>
                 scheduler configured for the device supports ionice. This is
                 only supported by BFQ or Kyber but is *not* supported by
                 mq-deadline. Please read the section about
-                :ref:`IO limiting<scrub-io-limiting>`.
+                :docref:`IO limiting <btrfs-scrub:scrub-io-limiting>`.
         -n <ioprio_classdata>
                 set IO priority classdata (see ``ionice(1)`` manpage)
         -q
@@ -184,7 +184,7 @@ status [options] <path>|<device>
         :file:`sysfs/fs/btrfs/FSID/devinfo/scrub_speed_max`. In that case
         the limit is printed on the *Rate:* line if option *-d* is specified,
         or without it on a single-device filesystem.  Read more about tat in
-        section about :ref:`scrub IO limiting<scrub-io-limiting>`.
+        section about :docref:`scrub IO limiting <btrfs-scrub:scrub-io-limiting>`.
 
         .. code-block:: none
 

Documentation/ch-mount-options.rst

@@ -27,7 +27,7 @@ acl, noacl
         The support for ACL is build-time configurable (BTRFS_FS_POSIX_ACL) and
         mount fails if *acl* is requested but the feature is not compiled in.
 
-.. _mount-option-autodefrag:
+.. duplabel:: mount-option-autodefrag
 
 autodefrag, noautodefrag
         (since: 3.0, default: off)
@@ -172,7 +172,7 @@ datasum, nodatasum
         The cost of checksumming of the blocks in memory is much lower than the IO,
         modern CPUs feature hardware support of the checksumming algorithm.
 
-.. _mount-option-degraded:
+.. duplabel:: mount-option-degraded
 
 degraded
         (default: off)
@@ -194,7 +194,7 @@ degraded
         then the constraint of single/data is not satisfied and the filesystem
         cannot be mounted.
 
-.. _mount-option-device:
+.. duplabel:: mount-option-device
 
 device=<devicepath>
         Specify a path to a device that will be scanned for BTRFS filesystem during

Documentation/ch-scrub-intro.rst

@@ -23,7 +23,7 @@ will continue from the last saved position.
 Scrub can be started only on a mounted filesystem, though it's possible to
 scrub only a selected device. See :ref:`btrfs scrub start<man-scrub-start>` for more.
 
-.. _scrub-io-limiting:
+.. duplabel:: scrub-io-limiting
 
 Bandwidth and IO limiting
 ^^^^^^^^^^^^^^^^^^^^^^^^^

Documentation/ch-volume-management-intro.rst

@@ -27,7 +27,7 @@ RAID level
         standard RAID levels. At the moment the supported ones are: RAID0, RAID1,
         RAID10, RAID5 and RAID6.
 
-.. _man-device-typical-use-cases:
+.. duplabel:: man-device-typical-use-cases
 
 Typical use cases
 -----------------