path: root/man/btrfs.8.in

.TH BTRFS 8 "" "btrfs" "btrfs"
.\"
.\" Man page written by Goffredo Baroncelli <kreijack@inwind.it> (Feb 2010)
.\" Modified by Qu Wenruo <quwenruo@cn.fujitsu.com> (Jun 2013)
.\"
.SH NAME
btrfs \- control a btrfs filesystem
.SH SYNOPSIS
\fBbtrfs\fP \fBsubvolume create\fP [-i \fI<qgroupid>\fP] [\fI<dest>\fP/]\fI<name>\fP
.PP
\fBbtrfs\fP \fBsubvolume delete\fP \fI<subvolume>\fP [\fI<subvolume>...\fP]
.PP
\fBbtrfs\fP \fBsubvolume list\fP [\fIoptions\fP] [-G [+|-]\fIvalue\fP] [-C [+|-]\fIvalue\fP] [--sort=rootid,gen,ogen,path] \fI<path>\fP
.PP
\fBbtrfs\fP \fBsubvolume snapshot\fP [-r] \fI<source>\fP \fI<dest>\fP|[\fI<dest>\fP/]\fI<name>\fP
.PP
\fBbtrfs\fP \fBsubvolume get-default\fP\fI <path>\fP
.PP
\fBbtrfs\fP \fBsubvolume set-default\fP\fI <id> <path>\fP
.PP
\fBbtrfs\fP \fBsubvolume find-new\fP\fI <subvolume> <lastgen>\fP
.PP
\fBbtrfs\fP \fBsubvolume show\fP\fI <path>\fP
.PP
.PP
\fBbtrfs\fP \fBfilesystem df\fP\fI <path>\fP
.PP
\fBbtrfs\fP \fBfilesystem show\fP [--all-devices|\fI<uuid>\fP|\fI<label>\fP]\fP
.PP
\fBbtrfs\fP \fBfilesystem sync\fP\fI <path> \fP
.PP
\fBbtrfs\fP \fBfilesystem defragment\fP [\fIoptions\fP] \fI<file>\fP|\fI<dir>\fP [\fI<file>\fP|\fI<dir>...\fP]\fP
.PP
\fBbtrfs\fP \fBfilesystem resize\fP [\fIdevid\fP:][+/\-]\fI<size>\fP[gkm]|[\fIdevid\fP:]\fImax <path>\fP
.PP
\fBbtrfs\fP \fBfilesystem label\fP [\fI<device>\fP|\fI<mount_point>\fP] [\fI<newlabel>\fP]
.PP
.PP
\fBbtrfs\fP \fB[filesystem] balance start\fP [\fIoptions\fP] \fI<path>\fP
.PP
\fBbtrfs\fP \fB[filesystem] balance pause\fP\fI <path>\fP
.PP
\fBbtrfs\fP \fB[filesystem] balance cancel\fP\fI <path>\fP
.PP
\fBbtrfs\fP \fB[filesystem] balance resume\fP\fI <path>\fP
.PP
\fBbtrfs\fP \fB[filesystem] balance status\fP [-v] \fI<path>\fP
.PP
.PP
\fBbtrfs\fP \fBdevice add\fP [-Kf] \fI<device>\fP [\fI<device>...\fP] \fI<path>\fP
.PP
\fBbtrfs\fP \fBdevice delete\fP \fI<device>\fP [\fI<device>...\fP] \fI<path>\fP
.PP
\fBbtrfs\fP \fBdevice scan\fP [--all-devices|\fI<device> \fP[\fI<device>...\fP]
.PP
\fBbtrfs\fP \fBdevice ready\fP\fI <device>\fP
.PP
\fBbtrfs\fP \fBdevice stats\fP [-z] {\fI<path>\fP|\fI<device>\fP}
.PP
.PP
\fBbtrfs\fP \fBscrub start\fP [-BdqrR] [-c \fIioprio_class\fP -n \fIioprio_classdata\fP] {\fI<path>\fP|\fI<device>\fP}
.PP
\fBbtrfs\fP \fBscrub cancel\fP {\fI<path>\fP|\fI<device>\fP}
.PP
\fBbtrfs\fP \fBscrub resume\fP [-BdqrR] [-c \fIioprio_class\fP -n \fIioprio_classdata\fP] {\fI<path>\fP|\fI<device>\fP}
.PP
\fBbtrfs\fP \fBscrub status\fP [-d] {\fI<path>\fP|\fI<device>\fP}
.PP
.PP
\fBbtrfs\fP \fBcheck\fP [\fIoptions\fP] \fI<device>\fP
.PP
\fBbtrfs\fP \fBrescue chunk-recover\fP [\fIoptions\fP] \fI<path>\fP
.PP
\fBbtrfs\fP \fBrestore\fP [\fIoptions\fP] \fI<device>\fP
.PP
.PP
\fBbtrfs\fP \fBinspect-internal inode-resolve\fP [-v] \fI<inode>\fP \fI<path>\fP
.PP
\fBbtrfs\fP \fBinspect-internal logical-resolve\fP [-Pv] [-s \fI<size>\fP] \fI<logical>\fP \fI<path>\fP
.PP
\fBbtrfs\fP \fBinspect-internal subvolid-resolve\fP \fI<subvolid>\fP \fI<path>\fP
.PP
\fBbtrfs\fP \fBinspect-internal rootid\fP \fI<path>\fP
.PP
.PP
\fBbtrfs\fP \fBsend\fP [-v] [-p \fI<parent>\fP] [-c \fI<clone-src>\fP] [-f \fI<outfile>\fP] \fI<subvol>\fP
.PP
\fBbtrfs\fP \fBreceive\fP [-ve] [-f \fI<infile>\fP] \fI<mount>\fP
.PP
.PP
\fBbtrfs\fP \fBquota enable\fP\fI <path>\fP
.PP
\fBbtrfs\fP \fBquota disable\fP\fI <path>\fP
.PP
\fBbtrfs\fP \fBquota rescan\fP [-s] \fI<path>\fP
.PP
.PP
\fBbtrfs\fP \fBqgroup assign\fP \fI<src>\fP \fI<dst>\fP \fI<path>\fP
.PP
\fBbtrfs\fP \fBqgroup remove\fP \fI<src>\fP \fI<dst>\fP \fI<path>\fP
.PP
\fBbtrfs\fP \fBqgroup create\fP \fI<qgroupid>\fP \fI<path>\fP
.PP
\fBbtrfs\fP \fBqgroup destroy\fP \fI<qgroupid>\fP \fI<path>\fP
.PP
\fBbtrfs\fP \fBqgroup show\fP \fI<path>\fP
.PP
\fBbtrfs\fP \fBqgroup limit\fP [\fIoptions\fP] \fI<size>\fP|\fBnone\fP [\fI<qgroupid>\fP] \fI<path>\fP
.PP
.PP
\fBbtrfs\fP \fBreplace start\fP [-Bfr] \fI<srcdev>\fP|\fI<devid> <targetdev> <mount_point>\fP
.PP
\fBbtrfs\fP \fBreplace status\fP [-1] \fI<mount_point>\fP
.PP
\fBbtrfs\fP \fBreplace cancel\fP \fI<mount_point>\fP
.PP
\fBbtrfs\fP \fBhelp|\-\-help \fP
.PP
\fBbtrfs\fP \fB<command> \-\-help \fP
.PP
.SH DESCRIPTION
.B btrfs
is used to control the filesystem and the files and directories stored. It is
the tool to create or destroy a snapshot or a subvolume for the
filesystem, to defrag a file or a directory, flush the data to the disk,
to resize the filesystem, to scan the device.

It is possible to abbreviate the commands unless the commands are ambiguous.
For example: it is possible to run
.I btrfs sub snaps
instead of
.I btrfs subvolume snapshot.
But
.I btrfs file s
is not allowed, because
.I file s
may be interpreted both as
.I filesystem show
and as
.I filesystem sync.
In this case
.I btrfs
returns filesystem sync
If a command is terminated by
.I --help
, the detailed help is showed. If the passed command matches more commands,
detailed help of all the matched commands is showed. For example
.I btrfs dev --help
shows the help of all
.I device*
commands.

.SH COMMANDS
.TP

\fBsubvolume create\fP [-i \fI<qgroupid>\fP] [\fI<dest>\fP/]\fI<name>\fP
Create a subvolume \fI<name>\fR in \fI<dest>\fR.
If \fI<dest>\fR is not given subvolume \fI<name>\fR will be created in the
current directory.
.RS

\fIOptions\fP
.IP "\fB-i\fP \fI<qgroupid>\fR" 5
Add the newly created subvolume to a qgroup. This option can be given multiple
times.
.RE
.TP

\fBsubvolume delete\fR\fI <subvolume> \fP[\fI<subvolume>...\fP]\fR
Delete the subvolume \fI<subvolume>\fR. If \fI<subvolume>\fR is not a
subvolume, \fBbtrfs\fR returns an error.
.TP

\fBsubvolume list\fR [\fIoptions\fP] [-G [+|-]\fIvalue\fP] [-C [+|-]\fIvalue\fP] [--sort=rootid,gen,ogen,path] \fI<path>\fR

List the subvolumes present in the filesystem \fI<path>\fR. For every
subvolume the following information is shown by default.
ID \fI<ID>\fP top level \fI<ID>\fP path \fI<path>\fP
where path is the relative path of the subvolume to the \fItop level\fR
subvolume.

The subvolume's ID may be used by the \fBsubvolume set-default\fR command, or
at mount time via the \fIsubvolid=\fR option.
If \fI-p\fR is given, then \fIparent <ID>\fR is added to the output between ID
and top level. The parent's ID may be used at mount time via the
\fIsubvolrootid=\fR option.
.RS

\fIOptions\fP
.IP "\fB-p\fP" 5
print parent ID.
.IP "\fB-a\fP" 5
print all the subvolumes in the filesystem and distinguish between
absolute and relative path with respect to the given \fI<path>\fP.
.IP "\fB-c\fP" 5
print the ogeneration of the subvolume, aliases: ogen or origin generation.
.IP "\fB-g\fP" 5
print the generation of the subvolume.
.IP "\fB-o\fP" 5
print only subvolumes bellow specified <path>.
.IP "\fB-u\fP" 5
print the UUID of the subvolume.
.IP "\fB-q\fP" 5
print the parent uuid of subvolumes (and snapshots).
.IP "\fB-t\fP" 5
print the result as a table.
.IP "\fB-s\fP" 5
only snapshot subvolumes in the filesystem will be listed.
.IP "\fB-r\fP" 5
only readonly subvolumes in the filesystem will be listed.
.IP "\fB-G [+|-]\fIvalue\fP\fP" 5
list subvolumes in the filesystem that its generation is
>=, <= or = \fIvalue\fP. '+' means >= \fIvalue\fP, '-' means <= \fIvalue\fP, If there is
neither '+' nor '-', it means = \fIvalue\fP.
.IP "\fB-C [+|-]\fIvalue\fP" 5
list subvolumes in the filesystem that its ogeneration is
>=, <= or = \fIvalue\fP. The usage is the same to '-g' option.
.IP "\fB--sort=rootid,gen,ogen,path\fP" 5
list subvolumes in order by specified items.
you can add '+' or '-' in front of each items, '+' means ascending, '-'
means descending. The default is ascending.

for \fB--sort\fP you can combine some items together by ',', just like
\f--sort=+ogen,-gen,path,rootid\fR.
.RE
.TP

\fBsubvolume snapshot\fP [-r] \fI<source>\fP \fI<dest>\fP|[\fI<dest>\fP/]\fI<name>\fP
Create a writable/readonly snapshot of the subvolume \fI<source>\fR with the
name \fI<name>\fR in the \fI<dest>\fR directory.
If only \fI<dest>\fR is given, the subvolume will be named the basename of \fI<source>\fR.
If \fI<source>\fR is not a subvolume, \fBbtrfs\fR returns an error.
If \fI-r\fR is given, the snapshot will be readonly.
.TP

\fBsubvolume get-default\fR\fI <path>\fR
Get the default subvolume of the filesystem \fI<path>\fR. The output format
is similar to \fBsubvolume list\fR command.
.TP

\fBsubvolume set-default\fR\fI <id> <path>\fR
Set the subvolume of the filesystem \fI<path>\fR which is mounted as
\fIdefault\fR. The subvolume is identified by \fI<id>\fR, which
is returned by the \fBsubvolume list\fR command.
.TP

\fBsubvolume find-new\fR\fI <subvolume> <last_gen>\fR
List the recently modified files in a subvolume, after \fI<last_gen>\fR ID.
.TP

\fBsubvolume show\fR\fI <path>\fR
Show information of a given subvolume in the \fI<path>\fR.
.TP

\fBfilesystem df\fP\fI <path>\fR
Show space usage information for a mount point.
.TP

\fBfilesystem show\fR [--all-devices|\fI<uuid>\fR|\fI<label>\fR]\fR
Show the btrfs filesystem with some additional info. If no \fIUUID\fP or
\fIlabel\fP is passed, \fBbtrfs\fR show info of all the btrfs filesystem.
If \fB--all-devices\fP is passed, all the devices under /dev are scanned;
otherwise the devices list is extracted from the /proc/partitions file.
.TP

\fBfilesystem sync\fR\fI <path> \fR
Force a sync for the filesystem identified by \fI<path>\fR.
.TP

\fBfilesystem defragment\fP [\fIoptions\fP] \fI<file>\fP|\fI<dir>\fP [\fI<file>\fP|\fI<dir>...\fP]\fP
Defragment file data and/or directory metadata. If \fB-r\fP is passed, 
files in \fIdir\fR will be defragmented recursively.


The start position and the number of bytes to defragment can be specified by
\fIstart\fR and \fIlen\fR. Any extent bigger than threshold 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.
.RS

\fIOptions\fR
.IP "\fB-v\fP" 5
be verbose
.IP "\fB-c\fP" 5
compress file contents while defragmenting
.IP "\fB-r\fP" 5
defragment files recursively
.IP "\fB-f\fP" 5
flush filesystem after defragmenting
.IP "\fB-s \fIstart\fP\fP" 5
defragment only from byte \fIstart\fR onward
.IP "\fB-l \fIlen\fP\fP" 5
defragment only up to \fIlen\fR bytes
.IP "\fB-t \fIsize\fP\fP" 5
defragment only files at least \fIsize\fR bytes big

For \fBstart\fP, \fBlen\fP, \fBsize\fP it is possible to append a suffix
like \fBk\fP for 1 KBytes, \fBm\fP for 1 MBytes...

NOTE: 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 \fBcp --reflink\fP.
.RE
.TP

.\"
.\" Some wording are extracted by the resize2fs man page
.\"
\fBfilesystem resize\fP [\fIdevid\fP:][+/\-]\fI<size>\fP[gkm]|[\fIdevid\fP:]\fImax <path>\fR
Resize a filesystem identified by \fI<path>\fR for the underlying device
\fIdevid\fR.  The \fIdevid\fR can be found with \fBbtrfs filesystem show\fR and
defaults to 1 if not specified.
The \fI<size>\fR parameter specifies the new size of the filesystem.
If the prefix \fI+\fR or \fI\-\fR is present the size is increased or decreased
by the quantity \fI<size>\fR.
If no units are specified, the unit of the \fI<size>\fR 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 \fIdevid\fR.

The \fBresize\fR command \fBdoes not\fR 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
\fBfdisk(8)\fR or \fBparted(8)\fR 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.
.TP

\fBfilesystem label\fP [\fI<dev>\fP|\fI<mount_point>\fP] [\fInewlabel\fP]\fP
Show or update the label of a filesystem. \fI[<device>|<mountpoint>]\fR is used
to identify the filesystem. 
If a \fInewlabel\fR optional argument is passed, the label is changed. The
following constraints exist for a label:
.IP
- the maximum allowable length shall be less than 256 chars
.TP

\fB[filesystem] balance start\fR [\fIoptions\fP] \fI<path>\fR
Balance chunks across the devices
Balance and/or convert (change allocation profile of) chunks that
passed all \fIfilters\fR in a comma-separated list of filters for a
particular chunk type.
If filter list is not given balance all chunks of that type.
In case none of the \fI-d\fR, \fI-m\fR or \fI-s\fR options is
given balance all chunks in a filesystem.
.RS

\fIOptions\fR
.IP "\fB-d[\fIfilters\fP]\fR" 5
act on data chunks
.IP "\fB-m[\fIfilters\fP]\fR" 5
act on metadata chunks
.IP "\fB-s[\fIfilters\fP]\fR" 5
act on system chunks (only under -f)
.IP "\fB-v\fP" 5
be verbose
.IP "\fB-f\fP" 5
force reducing of metadata integrity
.RE
.TP

\fB[filesystem] balance pause\fR\fI <path>\fR
Pause running balance.
.TP

\fB[filesystem] balance cancel\fR\fI <path>\fR
Cancel running or paused balance.
.TP

\fB[filesystem] balance resume\fR\fI <path>\fR
Resume interrupted balance.
.TP

\fB[filesystem] balance status\fR [-v] \fI<path>\fR
Show status of running or paused balance.
.RS

\fIOptions\fR
.IP "\fB-v\fP" 5
be verbose
.RE
.TP

\fBdevice add\fR\fI [-Kf] <dev> \fP[\fI<dev>...\fP] \fI<path>\fR
Add device(s) to the filesystem identified by \fI<path>\fR.
If applicable, a whole device discard (TRIM) operation is performed.
.RS

\fIOptions\fR
.IP "\fB-K|--nodiscard\fP" 5
do not perform discard by default
.IP "\fB-f|--force\fP" 5
force overwrite of existing filesystem on the given disk(s)
.RE
.TP

\fBdevice delete\fR\fI <dev> \fP[\fI<dev>...\fP] \fI<path>\fR
Remove device(s) from a filesystem identified by \fI<path>\fR.
.TP

\fBdevice scan\fR [--all-devices|\fI<device> \fP[\fI<device>...\fP]\fR
If one or more devices are passed, these are scanned for a btrfs filesystem. 
If no devices are passed, \fBbtrfs\fR scans all the block devices listed
in the /proc/partitions file.
Finally, if \fB--all-devices\fP is passed, all the devices under /dev are 
scanned.
.TP

\fBdevice ready\fR \fI<device>\fR
Check device to see if it has all of it's devices in cache for mounting.
.TP

\fBdevice stats\fP [-z] {\fI<path>\fP|\fI<device>\fP}
Read and print the device IO stats for all devices of the filesystem
identified by \fI<path>\fR or for a single \fI<device>\fR.
.RS

\fIOptions\fR
.IP "\fB-z\fP" 5
Reset stats to zero after reading them.
.RE
.TP

\fBscrub start\fP [-BdqrR] [-c \fIioprio_class\fP -n \fIioprio_classdata\fP] {\fI<path>\fP|\fI<device>\fP}
Start a scrub on all devices of the filesystem identified by \fI<path>\fR or on
a single \fI<device>\fR. Without options, scrub is started as a background
process. Progress can be obtained with the \fBscrub status\fR command. Scrubbing
involves reading all data from all disks and verifying checksums. Errors are
corrected along the way if possible.
.IP
The default IO priority of scrub is the idle class. The priority can be configured similar to the
.BR ionice (1)
syntax.
.RS

\fIOptions\fR
.IP "\fB-B\fP" 5
Do not background and print scrub statistics when finished.
.IP "\fB-d\fP" 5
Print separate statistics for each device of the filesystem (-B only).
.IP "\fB-q\fP" 5
Quiet. Omit error messages and statistics.
.IP "\fB-r\fP" 5
Read only mode. Do not attempt to correct anything.
.IP "\fB-R\fP" 5
Raw print mode. Print full data instead of summary.
.IP "\fB-c \fIioprio_class\fP" 5
Set IO priority class (see
.BR ionice (1)
manpage).
.IP "\fB-n \fIioprio_classdata\fP" 5
Set IO priority classdata (see
.BR ionice (1)
manpage).
.RE
.TP

\fBscrub cancel\fP {\fI<path>\fP|\fI<device>\fP}
If a scrub is running on the filesystem identified by \fI<path>\fR, cancel it.
Progress is saved in the scrub progress file and scrubbing can be resumed later
using the \fBscrub resume\fR command.
If a \fI<device>\fR is given, the corresponding filesystem is found and
\fBscrub cancel\fP behaves as if it was called on that filesystem.
.TP

\fBscrub resume\fP [-BdqrR] [-c ioprio_class -n ioprio_classdata] {\fI<path>\fP|\fI<device>\fP}
Resume a canceled or interrupted scrub cycle on the filesystem identified by
\fI<path>\fR or on a given \fI<device>\fR. Does not start a new scrub if the
last scrub finished successfully.
.RS

\fIOptions\fR
.TP
see \fBscrub start\fP.
.RE
.TP

\fBscrub status\fP [-d] {\fI<path>\fP|\fI<device>\fP}
Show status of a running scrub for the filesystem identified by \fI<path>\fR or
for the specified \fI<device>\fR.
If no scrub is running, show statistics of the last finished or canceled scrub
for that filesystem or device.
.RS

\fIOptions\fR
.IP "\fB-d\fP" 5
Print separate statistics for each device of the filesystem.
.RE
.TP

\fBcheck\fR [\fIoptions\fP] <device>\fR
Check an unmounted btrfs filesystem.
.RS

\fIOptions\fR
.IP "\fB-s|--support \fI<superblock>\fP\fR" 5
use this superblock copy.
.IP "\fB--repair\fP" 5
try to repair the filesystem.
.IP "\fB--init-csum-tree\fP" 5
create a new CRC tree.
.IP "\fB--init-extent-tree\fP" 5
create a new extent tree.
.RE
.TP

\fBrescue chunk-recover\fR [\fIoptions\fP] <device>\fR
Recover the chunk tree by scanning the devices one by one.
.RS

\fIOptions\fR
.IP "\fB-y\fP" 5
assume an answer of 'yes' to all questions.
.IP "\fB-v\fP" 5
verbose mode.
.IP "\fB-h\fP" 5
help.
.RE
.TP

\fBrestore\fR [\fIoptions\fP] <device>\fR
Try to restore files from a damaged filesystem(unmounted).
.RS

\fIOptions\fR
.IP "\fB-s\fP" 5
get snapshots.
.IP "\fB-x\fP" 5
get extended attributes.
.IP "\fB-v\fP" 5
verbose.
.IP "\fB-i\fP" 5
ignore errors.
.IP "\fB-o\fP" 5
overwrite.
.IP "\fB-t \fI<location>\fP\fP" 5
tree location.
.IP "\fB-f \fI<offset>\fP\fP" 5
filesystem location.
.IP "\fB-u \fI<block>\fP\fP" 5
super mirror.
.IP "\fB-r \fI<rootid>\fP\fP" 5
root objectid.
.IP "\fB-d\fP" 5
find dir.
.IP "\fB-l\fP" 5
list tree roots.
.RE
.TP

\fBinspect-internal inode-resolve\fP [-v] \fI<inode>\fP \fI<path>\fP
Resolves an <inode> in subvolume <path> to all filesystem paths.
.RS

\fIOptions\fR
.IP "\fB-v\fP" 5
verbose mode. print count of returned paths and ioctl() return value
.RE
.TP

\fBinspect-internal logical-resolve\fP [-Pv] [-s bufsize] \fI<logical>\fP \fI<path>\fP
Resolves a <logical> address in the filesystem mounted at <path> to all inodes.
By default, each inode is then resolved to a file system path (similar to the
\fBinode-resolve\fP subcommand).
.RS

\fIOptions\fR
.IP "\fB-P\fP" 5
skip the path resolving and print the inodes instead
.IP "\fB-v\fP" 5
verbose mode. print count of returned paths and all ioctl() return values
.IP "\fB-s \fI<bufsize>\fP" 5
set inode container's size. This is used to increase inode container's size in case it is
not enough to read all the resolved results. The max value one can set is 64k.
.RE
.TP

\fBinspect-internal subvolid-resolve\fP \fI<subvolid> <path>\fP
Get file system paths for the given subvolume ID.
.TP

\fBinspect-internal rootid\fP \fI<path>\fP
For a given file or directory, return the containing tree root id. For a
subvolume return it's own tree id.

The result is undefined for the so-called empty subvolumes (identified by inode number 2).
.TP

\fBsend\fP [-v] [-p \fI<parent>\fP] [-c \fI<clone-src>\fP] [-f \fI<outfile>\fP] \fI<subvol>\fP
Send the subvolume to stdout.
Sends the subvolume specified by \fI<subvol>\fR to stdout.
By default, this will send the whole subvolume. To do an incremental
send, use '\fI-p <parent>\fR'. If you want to allow btrfs to clone from
any additional local snapshots, use '\fI-c <clone-src>\fR' (multiple times
where applicable). You must not specify clone sources unless you
guarantee that these snapshots are exactly in the same state on both
sides, the sender and the receiver. It is allowed to omit the
'\fI-p <parent>\fR' option when '\fI-c <clone-src>\fR' options are given, in
which case '\fBbtrfs send\fP' will determine a suitable parent among the
clone sources itself.
.RS

\fIOptions\fR
.IP "\fB-v\fP" 5
Enable verbose debug output. Each occurrence of this option increases the
verbose level more.
.IP "\fB-p \fI<parent>\fP" 5
Send an incremental stream from \fI<parent>\fR to \fI<subvol>\fR.
.IP "\fB-c \fI<clone-src>\fP" 5
Use this snapshot as a clone source for an incremental send (multiple allowed).
.IP "\fB-f \fI<outfile>\fP" 5
Output is normally written to stdout. To write to a file, use this option.
An alternative would be to use pipes.
.RE
.TP

\fBreceive\fP [-ve] [-f \fI<infile>\fR] \fI<mount>\fR
Receive subvolumes from stdin.
Receives one or more subvolumes that were previously
sent with btrfs send. The received subvolumes are stored
into \fI<mount>\fP.
btrfs receive will fail in case a receiving subvolume
already exists. It will also fail in case a previously
received subvolume was changed after it was received.
After receiving a subvolume, it is immediately set to
read only.
.RS

\fIOptions\fR
.IP "\fB-v\fP" 5
Enable verbose debug output. Each occurrence of this option increases the
verbose level more.
.IP "\fB-f \fI<infile>\fR" 5
By default, btrfs receive uses stdin to receive the subvolumes.
Use this option to specify a file to use instead.
.IP "\fB-e\fP" 5
Terminate after receiving an <end cmd> in the data stream.
Without this option, the receiver terminates only if an error is recognized or on EOF.
.RE
.TP

\fBquota enable\fR \fI<path>\fR
Enable subvolume quota support for a filesystem.
.TP

\fBquota disable\fR \fI<path>\fR
Disable subvolume quota support for a filesystem.
.TP

\fBquota rescan\fR [-s] \fI<path>\fR
Trash all qgroup numbers and scan the metadata again with the current config.
.RS

\fIOptions\fR
.IP "\fB-s\fP" 5
show status of a running rescan operation.
.RE
.TP

\fBqgroup assign\fP \fI<src> <dst> <path>\fP
Enable subvolume qgroup support for a filesystem.
.TP

\fBqgroup remove\fP \fI<src> <dst> <path>\fP
Remove a subvol from a quota group.
.TP

\fBqgroup create\fP \fI<qgroupid> <path>\fP
Create a subvolume quota group.
.TP

\fBqgroup destroy\fP \fI<qgroupid> <path>\fP
Destroy a subvolume quota group.
.TP

\fBqgroup show\fP \fI<path>\fP
Show all subvolume quota groups.
.TP

\fBqgroup limit\fP [\fIoptions\fP] \fI<size>\fP|\fBnone\fP [\fI<qgroupid>\fP] \fI<path>\fP
Limit the size of a subvolume quota group.
.TP

\fBreplace start\fR [-Bfr] \fI<srcdev>\fP|\fI<devid> <targetdev> <path>\fR
Replace device of a btrfs filesystem.
On a live filesystem, duplicate the data to the target device which
is currently stored on the source device. If the source device is not
available anymore, or if the \fB-r\fR option is set, the data is built
only using the RAID redundancy mechanisms. After completion of the
operation, the source device is removed from the filesystem.
If the \fI<srcdev>\fR is a numerical value, it is assumed to be the device id
of the filesystem which is mounted at mount_point, otherwise is is
the path to the source device. If the source device is disconnected,
from the system, you have to use the \fIdevid\fR parameter format.
The \fI<targetdev>\fP needs to be same size or larger than the \fI<srcdev>\fR.
.RS

\fIOptions\fR
.IP "\fB-r\fP" 5
only read from \fI<srcdev>\fR if no other zero-defect mirror exists (enable
this if your drive has lots of read errors, the access would be very slow)
.IP "\fB-f\fP" 5
force using and overwriting \fI<targetdev>\fR even if it looks like
containing a valid btrfs filesystem. A valid filesystem is
assumed if a btrfs superblock is found which contains a
correct checksum. Devices which are currently mounted are
never allowed to be used as the \fI<targetdev>\fR
.IP "\fB-B\fP" 5
do not background
.RE
.TP

\fBreplace status\fR [-1] \fI<mount_point>\fR
Print status and progress information of a running device replace operation.
.RS

\fIOptions\fR
.IP "\fB-1\fP" 5
print once instead of print continuously until the replace
operation finishes (or is canceled)
.RE
.TP

\fBreplace cancel\fR \fI<mount_point>\fR
Cancel a running device replace operation.
.RE

.SH EXIT STATUS
\fBbtrfs\fR returns a zero exist status if it succeeds. Non zero is returned in
case of failure.

.SH AVAILABILITY
.B btrfs
is part of btrfs-progs. Btrfs filesystem is currently under heavy development,
and not suitable for any uses other than benchmarking and review.
Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for
further details.
.SH SEE ALSO
.BR mkfs.btrfs (8),
.BR ionice (1)