SUBVOLUME AND SNAPSHOT
----------------------
-A subvolume is a part of filesystem with it's own and independent
+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.
there are more arguments to process.
+
The corresponding directory is removed instantly but the data blocks are
-removed later. The deletion does not involve full 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 media.
+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`
+
for --sort you can combine some items together by \',', just like
--sort=+ogen,-gen,path,rootid.
-*set-default* <id> <path>::
-Set the subvolume of the filesystem <path> which is mounted as
-default.
+*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 (ie. the one mounted with 'subvol=/' or 'subvolid=5').
+Takes action on next mount.
+
-The subvolume is identified by <id>, which is returned by the *subvolume list*
-command.
+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* <path>::
Show information of a given subvolume in the <path>.
*snapshot* [-r] <source> <dest>|[<dest>/]<name>::
-Create a writable/readonly snapshot of the subvolume <source> with the
+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.
-If '-r' is given, the snapshot will be readonly.
++
+`Options`
++
+-r::::
+Make the new snapshot read only.
*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 meanwhile.
-The status of subvolume ids is checked periodically.
+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`
+