path: root/Documentation
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authorQu Wenruo <>2014-04-02 16:29:24 +0800
committerDavid Sterba <>2014-04-22 14:15:22 +0200
commit05c6d72830d3b08f1803e205a13c310f689ae801 (patch)
tree4081b2e4c70dfdf175f446513656c05e795f3f13 /Documentation
parent88b532914f2e7dcc654b359ec6340f14f1653e57 (diff)
btrfs-progs: Convert and enhance the man page of btrfs-qgroup.
Convert and enhance the man page of btrfs-qgroup. The original man page for btrfs-qgroup subcommand is almost useless for new user(like me), so adds more information on it. Signed-off-by: Qu Wenruo <> Signed-off-by: David Sterba <>
Diffstat (limited to 'Documentation')
2 files changed, 111 insertions, 0 deletions
diff --git a/Documentation/Makefile b/Documentation/Makefile
index 645a8e4c..84a48599 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -27,6 +27,7 @@ MAN8_TXT += btrfs-inspect-internal.txt
MAN8_TXT += btrfs-send.txt
MAN8_TXT += btrfs-receive.txt
MAN8_TXT += btrfs-quota.txt
+MAN8_TXT += btrfs-qgroup.txt
#MAN8_TXT += btrfs-replace.txt
#MAN8_TXT += btrfs-dedup.txt
diff --git a/Documentation/btrfs-qgroup.txt b/Documentation/btrfs-qgroup.txt
new file mode 100644
index 00000000..d0544232
--- /dev/null
+++ b/Documentation/btrfs-qgroup.txt
@@ -0,0 +1,110 @@
+btrfs-qgroup - control the quota group of a btrfs filesystem
+'btrfs qgroup' <subcommand> <args>
+'btrfs qgroup' is used to control quota group(qgroup) of a btrfs filesystem.
+NOTE: To use qgroup, it needs to enable quota first using 'btrfs quota'
+WARNING: Qgroup is not stable yet and will impact performance in current mainline
+kernel(v3.14 so far).
+Quota group or qgroup in btrfs has its hierarchy like subvolume.
+One subvolume/snapshot can reach its quota limits if it consumes all the quota
+assigned to it or any of the parent qgroup(s).
+Also for snapshot, it consumes no quota initially since all its data
+shares with its parent, so only modification in snapshot consumes quota.
+Every subvolume/snapshot will have its own qgroup with id '0/<subvolume id>'
+upon creating, but can be later destroyed by 'btrfs qgroup destroy' command.
+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.
+'assign' <src> <dst> <path>::
+Assign qgroup <src> as the child qgroup of <dst> in the btrfs filesystem
+identified by <path>.
+'remove' <src> <dst> <path>::
+Remove the relationship between child qgroup <src> and parent qgroup <dst> in
+the btrfs filesystem identified by <path>.
+'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.
+'show' [options] <path>::
+Show all qgroups in the btrfs filesystem identified by <path>.
+print parent qgroup id.
+print child qgroup id.
+print max referenced size of qgroup.
+print max exclusive size of qgroup.
+list all qgroups which impact the given path(include ancestral qgroups)
+list all qgroups which impact the given path(exclude ancestral qgroups)
+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 ATTRs is given, use comma to separate.
+'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.
+'btrfs qgroup' returns a zero exist status if it succeeds. Non zero is
+returned in case of failure.
+'btrfs' is part of btrfs-progs. Btrfs filesystem is currently under heavy
+and not suitable for any uses other than benchmarking and review.
+Please refer to the btrfs wiki for
+further details.