BTRFS-FILESYSTEM(8) Btrfs Manual BTRFS-FILESYSTEM(8)NAME
btrfs-filesystem - control btrfs filesystem
SYNOPSIS
btrfs filesystem <subcommand> <args>
DESCRIPTION
btrfs filesystem is used to do the filesystem level control jobs,
including all the regular filesystem operations like setting/getting
label, resizing, defragment.
SUBCOMMAND
df <path> [<path>...]
Show space usage information for a mount point.
show [--mounted|--all-devices|<path>|<uuid>|<device>|<label>]
Show the btrfs filesystem with some additional info.
If no option nor <path>|<uuid>|<device>|<label> is passed, btrfs
shows information of all the btrfs filesystem both mounted and
unmounted. If --mounted is passed, it would probe btrfs kernel to
list mounted btrfs filesystem(s); If --all-devices is passed, all
the devices under /dev are scanned; otherwise the devices list is
extracted from the /proc/partitions file.
sync <path>
Force a sync for the filesystem identified by <path>.
defragment [options] <file>|<dir> [<file>|<dir>...]
Defragment file data and/or directory metadata online.
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. Any
extent bigger than threshold given by -t option, will be considered
already defragged. Use 0 to take the kernel default, and use 1 to
say every single extent must be rewritten. You can also turn on
compression in defragment operations.
Options
-v
be verbose
-c
compress file contents while defragmenting
-r
defragment files recursively
-f
flush filesystem after defragmenting
-s <start>
defragment only from byte <start> onward
-l <len>
defragment only up to <len> bytes
-t <size>
defragment only files at least <size> bytes big
For <start>, <len>, <size> it is possible to append a suffix
like k for 1 KBytes, m for 1 MBytes...
Warning
defragmenting with kernels up to 2.6.37 will unlink COW-ed
copies of data, don’t use it if you use snapshots, have
de-duplicated your data or made copies with cp --reflink.
resize [<devid>:][+/-]<size>[gkm]|[<devid>:]max <path>
Resize a filesystem identified by <path> for the underlying device
devid online.
The devid can be found with btrfs filesystem show and defaults to 1
if not specified. The <size> parameter specifies the new size of
the filesystem. If the prefix + or - is present the size is
increased or decreased by the quantity <size>. If no units are
specified, the unit of the <size> parameter defaults to bytes.
Optionally, the size parameter may be suffixed by one of the
following units designators: 'K', 'M', or 'G', kilobytes,
megabytes, or gigabytes, respectively.
If 'max' is passed, the filesystem will occupy all available space
on the device devid.
The resize command does not manipulate the size of underlying
partition. If you wish to enlarge/reduce a filesystem, you must
make sure you can expand the partition before enlarging the
filesystem and shrink the partition after reducing the size of the
filesystem. This can done using fdisk(8) or parted(8) to delete the
existing partition and recreate it with the new desired size. When
recreating the partition make sure to use the same starting disk
cylinder as before.
label [<dev>|<mountpoint>] [<newlabel>]
Show or update the label of a filesystem.
[<device>|<mountpoint>] is used to identify the filesystem. If a
newlabel optional argument is passed, the label is changed. NOTE:
the maximum allowable length shall be less than 256 chars
EXIT STATUS
btrfs filesystem returns a zero exist status if it succeeds. Non zero
is returned in case of failure.
AVAILABILITY
btrfs is part of btrfs-progs. Please refer to the btrfs wiki
http://btrfs.wiki.kernel.org for further details.
SEE ALSOmkfs.btrfs(8),
Btrfs v3.14.2 05/30/2014 BTRFS-FILESYSTEM(8)