btrfs-progs: update docs and completion for tree-stats

Signed-off-by: Alexander Fougner <fougner89@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Documentation/btrfs-inspect-internal.asciidoc

@@ -136,6 +136,16 @@ inode number 2), but such subvolume does not contain any files anyway
 +
 resolve the absolute path of a the subvolume id 'subvolid'
 
+*tree-stats* [options] <device>::
+(needs root privileges)
++
+Print sizes and statistics of trees.
++
+`Options`
++
+-b::::
+Print raw numbers in bytes.
+
 EXIT STATUS
 -----------
 *btrfs inspect-internal* returns a zero exit status if it succeeds. Non zero is

btrfs-completion

@@ -36,7 +36,7 @@ _btrfs()
     commands_device='scan add delete remove ready stats usage'
     commands_scrub='start cancel resume status'
     commands_rescue='chunk-recover super-recover'
-    commands_inspect_internal='inode-resolve logical-resolve subvolid-resolve rootid min-dev-size dump-tree dump-super'
+    commands_inspect_internal='inode-resolve logical-resolve subvolid-resolve rootid min-dev-size dump-tree dump-super tree-stats'
     commands_property='get set list'
     commands_quota='enable disable rescan'
     commands_qgroup='assign remove create destroy show limit'