If conflicting options are passed, the last one takes precedence.
*defragment* [options] <file>|<dir> [<file>|<dir>...]::
-Defragment file data on a mounted filesytem.
+Defragment file data on a mounted filesystem.
+
If '-r' is passed, files in dir will be defragmented recursively.
The start position and the number of bytes to defragment can be specified by
-start and len using '-s' and '-l' options below.
+start and length using '-s' and '-l' options below.
Extents bigger than value given by '-t' will be skipped, otherwise this value
is used as a target extent size, but is only advisory and may not be reached
if the free space is too fragmented.
defragment certain internal trees (extent tree and the subvolume tree). This has been
confusing and could be removed in the future.
+*du* [options] <path> [<path>..]::
+Calculate disk usage of the target files using FIEMAP. For individual
+files, it will report a count of total bytes, and exclusive (not
+shared) bytes. We also calculate a 'set shared' value which is
+described below.
++
+Each argument to 'btrfs fi du' will have a 'set shared' value
+calculated for it. We define each 'set' as those files found by a
+recursive search of an argument. The 'set shared' value
+then is a sum of all shared space referenced by the set.
++
+'set shared' takes into account overlapping shared extents, hence it
+isn't as simple as adding up shared extents.
++
+`Options`
++
+-s|--summarize::::
+display only a total for each argument
+--raw::::
+raw numbers in bytes, without the 'B' suffix.
+--human-readable::::
+print human friendly numbers, base 1024, this is the default
+--iec::::
+select the 1024 base for the following options, according to the IEC standard.
+--si::::
+select the 1000 base for the following options, according to the SI standard.
+--kbytes::::
+show sizes in KiB, or kB with --si.
+--mbytes::::
+show sizes in MiB, or MB with --si.
+--gbytes::::
+show sizes in GiB, or GB with --si.
+--tbytes::::
+show sizes in TiB, or TB with --si.
+
*label* [<dev>|<mountpoint>] [<newlabel>]::
Show or update the label of a filesystem. This works on a mounted filesystem or
a filesystem image.