From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Evgeny A. Marchenko" <xengine@mail.ru>
Subject: Re: Question: Build btrfs filesystem from specific directory.
Date: Sat, 12 Jun 2010 06:33:11 +0400
Message-ID: <201006120633.12043.xengine@mail.ru>
References: <AANLkTimbW5pNGsFxRZYRRjY0Ke-Wyb4aaBkUZgilVMlR@mail.gmail.com>
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> I'm founding the solution to build btrfs filesystem image from
> specific directory.
> it's common concept at mobile build environment.
> e.g., ubifs and cramfs support this feature.
> 
> In case of ubifs
> -r, -d, --root=DIR       build file system from directory DIR
> In case of cramfs
> dirname    root of the filesystem to be compressed
> 
> But btrfs doesn't support it.
Maybe because btrfs is not a compressed read-only filesystem

> So does it have any plan to support this feature at btrfs?
You can create file-backed loop device, mount it and copy the directory 
contents there. Than unmount the loop and voila - you have btrfs image

Regards, Evgeny Marchenko