Provided by: btrfs-progs_5.2.1-1ubuntu1_amd64 bug

NAME

       btrfs-subvolume - manage btrfs subvolumes

SYNOPSIS

       btrfs subvolume <subcommand> [<args>]

DESCRIPTION

       btrfs subvolume is used to create/delete/list/show btrfs subvolumes and snapshots.

SUBVOLUME AND SNAPSHOT

       A subvolume is a part of filesystem with its own independent file/directory hierarchy.
       Subvolumes can share file extents. A snapshot is also subvolume, but with a given initial
       content of the original subvolume.

           Note
           A subvolume in btrfs is not like an LVM logical volume, which is block-level snapshot
           while btrfs subvolumes are file extent-based.

       A subvolume looks like a normal directory, with some additional operations described
       below. Subvolumes can be renamed or moved, nesting subvolumes is not restricted but has
       some implications regarding snapshotting.

       A subvolume in btrfs can be accessed in two ways:

       ·   like any other directory that is accessible to the user

       ·   like a separately mounted filesystem (options subvol or subvolid)

       In the latter case the parent directory is not visible and accessible. This is similar to
       a bind mount, and in fact the subvolume mount does exactly that.

       A freshly created filesystem is also a subvolume, called top-level, internally has an id
       5. This subvolume cannot be removed or replaced by another subvolume. This is also the
       subvolume that will be mounted by default, unless the default subvolume has been changed
       (see subcommand set-default).

       A snapshot is a subvolume like any other, with given initial content. By default,
       snapshots are created read-write. File modifications in a snapshot do not affect the files
       in the original subvolume.

SUBCOMMAND

       create [-i <qgroupid>] [<dest>/]<name>
           Create a subvolume <name> in <dest>.

           If <dest> is not given, subvolume <name> will be created in the current directory.

           Options

           -i <qgroupid>
               Add the newly created subvolume to a qgroup. This option can be given multiple
               times.

       delete [options] <subvolume> [<subvolume>...]
           Delete the subvolume(s) from the filesystem.

           If <subvolume> is not a subvolume, btrfs returns an error but continues if there are
           more arguments to process.

           The corresponding directory is removed instantly but the data blocks are removed later
           in the background. The command returns immediately. See btrfs subvolume sync how to
           wait until the subvolume gets completely removed.

           The deletion does not involve full transaction commit by default due to performance
           reasons. As a consequence, the subvolume may appear again after a crash. Use one of
           the --commit options to wait until the operation is safely stored on the device.

           Options

           -c|--commit-after
               wait for transaction commit at the end of the operation.

           -C|--commit-each
               wait for transaction commit after deleting each subvolume.

           -v|--verbose
               verbose output of operations.

       find-new <subvolume> <last_gen>
           List the recently modified files in a subvolume, after <last_gen> generation.

       get-default <path>
           Get the default subvolume of the filesystem <path>.

           The output format is similar to subvolume list command.

       list [options] [-G [+|-]<value>] [-C [+|-]<value>] [--sort=rootid,gen,ogen,path] <path>
           List the subvolumes present in the filesystem <path>.

           For every subvolume the following information is shown by default:

           ID <ID> gen <generation> top level <ID> path <path>

           where ID is subvolume’s id, gen is an internal counter which is updated every
           transaction, top level is the same as parent subvolume’s id, and path is the relative
           path of the subvolume to the top level subvolume. The subvolume’s ID may be used by
           the subvolume set-default command, or at mount time via the subvolid= option.

           Options

           Path filtering

               -o
                   print only subvolumes below specified <path>.

               -a
                   print all the subvolumes in the filesystem and distinguish between absolute
                   and relative path with respect to the given <path>.

           Field selection

               -p
                   print the parent ID (parent here means the subvolume which contains this
                   subvolume).

               -c
                   print the ogeneration of the subvolume, aliases: ogen or origin generation.

               -g
                   print the generation of the subvolume (default).

               -u
                   print the UUID of the subvolume.

               -q
                   print the parent UUID of the subvolume (parent here means subvolume of which
                   this subvolume is a snapshot).

               -R
                   print the UUID of the sent subvolume, where the subvolume is the result of a
                   receive operation.

           Type filtering

               -s
                   only snapshot subvolumes in the filesystem will be listed.

               -r
                   only readonly subvolumes in the filesystem will be listed.

               -d
                   list deleted subvolumes that are not yet cleaned.

           Other

               -t
                   print the result as a table.

           Sorting

               -G [+|-]<value>
                   list subvolumes in the filesystem that its generation is >=, ⟨ or = value. '+'
                   means >= value, '-' means <= value, If there is neither '+' nor '-', it means
                   = value.

               -C [+|-]<value>
                   list subvolumes in the filesystem that its ogeneration is >=, <= or = value.
                   The usage is the same to -G option.

               --sort=rootid,gen,ogen,path
                   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 --sort you can combine some items together by ',', just like
                   --sort=+ogen,-gen,path,rootid.

       set-default [<subvolume>|<id> <path>]
           Set the default subvolume for the (mounted) filesystem.

           Set the default subvolume for the (mounted) filesystem at <path>. This will hide the
           top-level subvolume (i.e. the one mounted with subvol=/ or subvolid=5). Takes action
           on next mount.

           There are two ways how to specify the subvolume, by <id> or by the <subvolume> path.
           The id can be obtained from btrfs subvolume list, btrfs subvolume show or btrfs
           inspect-internal rootid.

       show [options] <path>
           Show more information about subvolume <path> regarding UUIDs, times, generations,
           flags and related snapshots.

               /mnt/btrfs/subvolume
                       Name:                   subvolume
                       UUID:                   5e076a14-4e42-254d-ac8e-55bebea982d1
                       Parent UUID:            -
                       Received UUID:          -
                       Creation time:          2018-01-01 12:34:56 +0000
                       Subvolume ID:           79
                       Generation:             2844
                       Gen at creation:        2844
                       Parent ID:              5
                       Top level ID:           5
                       Flags:                  -
                       Snapshot(s):

           Options

           -r|--rootid
               rootid of the subvolume.

           -u|--uuid
               UUID of the subvolume.

       snapshot [-r|-i <qgroupid>] <source> <dest>|[<dest>/]<name>
           Create a snapshot of the subvolume <source> with the name <name> in the <dest>
           directory.

           If only <dest> is given, the subvolume will be named the basename of <source>. If
           <source> is not a subvolume, btrfs returns an error.

           Options

           -r
               Make the new snapshot read only.

           -i <qgroupid>
               Add the newly created subvolume to a qgroup. This option can be given multiple
               times.

       sync <path> [subvolid...]
           Wait until given subvolume(s) are completely removed from the filesystem after
           deletion. If no subvolume id is given, wait until all current deletion requests are
           completed, but do not wait for subvolumes deleted in the meantime.

           Options

           -s <N>
               sleep N seconds between checks (default: 1)

EXIT STATUS

       btrfs subvolume returns a zero exit status if it succeeds. A non-zero value 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), mount(8), btrfs-quota(8), btrfs-qgroup(8),