Provided by: btrfs-tools_4.4-1_i386 bug

NAME

       btrfs-qgroup - control the quota group of a btrfs filesystem

SYNOPSIS

       btrfs qgroup <subcommand> <args>

DESCRIPTION

       btrfs qgroup is used to control quota group (qgroup) of a btrfs
       filesystem.

           Note
           To use qgroup you need to enable quota first using btrfs quota
           enable command.

           Warning
           Qgroup is not stable yet and will impact performance in current
           mainline kernel (v3.14 so far).

QGROUP

       Quota groups or qgroup in btrfs make a tree hierarchy, the leaf qgroups
       are attached to subvolumes. The size limits are set per qgroup and
       apply when any limit is reached in tree that contains a given
       subvolume.

       The limit sare separated between shared and exclusive and reflect the
       extent ownership. For example a fresh snapshot shares almost all the
       blocks with the original subvolume, new writes to either subvolume will
       raise towards the exclusive limit.

       The qgroup identifiers conform to level/id where level 0 is reserved to
       the qgroups associated with subvolumes. Such qgroups are created
       automatically.

       The qgroup hierarchy is built by commands create and assign.

           Note
           If the qgroup of a subvolume is destroyed, quota about the
           subvolume will not be functional until qgroup 0/<subvolume id> is
           created again.

SUBCOMMAND

       assign [options] <src> <dst> <path>
           Assign qgroup <src> as the child qgroup of <dst> in the btrfs
           filesystem identified by <path>.

           Options

           --rescan
               Automatically schedule quota rescan if the new qgroup
               assignment leads to quota inconsistency.

           --no-rescan
               Explicitly ask not to do a rescan.

       create <qgroupid> <path>
           Create a subvolume quota group.

           For the 0/<subvolume id> qgroup, a qgroup can be created even
           before the subvolume created.

       destroy <qgroupid> <path>
           Destroy a qgroup.

           If a qgroup is no isolated,which means it is a parent or child
           qgroup, it can’t be destroyed.

       limit [options] <size>|none [<qgroupid>] <path>
           Limit the size of a qgroup to <size> or no limit in the btrfs
           filesystem identified by <path>.

           If <qgroupid> is not given, qgroup of the subvolume identified by
           <path> is used if possible.

           Options

           -c
               limit amount of data after compression. This is the default, it
               is currently not possible to turn off this option.

           -e
               limit space exclusively assigned to this qgroup.

       remove <src> <dst> <path>
           Remove the relationship between child qgroup <src> and parent
           qgroup <dst> in the btrfs filesystem identified by <path>.

       show [options] <path>
           Show all qgroups in the btrfs filesystem identified by <path>.

           Options

           -p
               print parent qgroup id.

           -c
               print child qgroup id.

           -r
               print limit of referenced size of qgroup.

           -e
               print limit of exclusive size of qgroup.

           -F
               list all qgroups which impact the given path(include ancestral
               qgroups)

           -f
               list all qgroups which impact the given path(exclude ancestral
               qgroups)

           --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.

           --sort=[+/-]<attr>[,[+/-]<attr>]...
               list qgroups in order of <attr>.

               <attr> can be one or more of
               qgroupid,rfer,excl,max_rfer,max_excl.

               Prefix '+' means ascending order and '-' means descending order
               of <attr>. If no prefix is given, use ascending order by
               default.

               If multiple <attr>s is given, use comma to separate.

EXIT STATUS

       btrfs qgroup returns a zero exit 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 ALSO

       mkfs.btrfs(8), btrfs-subvolume(8), btrfs-quota(8),