[lxc-devel] [lxd/master] doc: add not about escaping btrfs qgroups

[brauner on Github]

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From 13c47b40615dedf6e608469ab32f1b84e0885d5f Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at ubuntu.com>
Date: Mon, 24 Apr 2017 14:56:41 +0200
Subject: [PATCH] doc: add not about escaping btrfs qgroups

Closes #3135.

Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>
---
 doc/storage.md | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/doc/storage.md b/doc/storage.md
index 5526b4d..84b7cb7 100644
--- a/doc/storage.md
+++ b/doc/storage.md
@@ -135,7 +135,13 @@ lxc storage create pool2 dir source=/data/lxd
 ### Btrfs
 
  - Uses a subvolume per container, image and snapshot, creating btrfs snapshots when creating a new object.
- - btrfs can be used as a storage backend inside a container (nesting), so long as the parent container is itself on btrfs.
+ - btrfs can be used as a storage backend inside a container (nesting), so long as the parent container is itself on btrfs. (But see notes about btrfs quota via qgroups.)
+ - btrfs supports storage quotas via qgroups. While btrfs qgroups are
+   hierarchical, new subvolumes will not automatically be added to the qgroups
+   of their parent subvolumes. This means that users can trivially escape any
+   quotas that are set. If adherence to strict quotas is a necessity users
+   should be mindful of this and maybe consider using a zfs storage pool with
+   refquotas.
 
 #### The following commands can be used to create BTRFS storage pools