Question: Build btrfs filesystem from specific directory.

Question: Build btrfs filesystem from specific directory.

[Kyungmin Park]

Dear all,

I'm not sure it's correct mailing list. but I can't find a btrfs-progs
mailing list.

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.
usage: mkfs.btrfs [options] dev [ dev ... ]
options:
         -A --alloc-start the offset to start the FS
         -b --byte-count total number of bytes in the FS
         -d --data data profile, raid0, raid1, raid10 or single
         -l --leafsize size of btree leaves
         -L --label set a label
         -m --metadata metadata profile, values like data profile
         -n --nodesize size of btree nodes
         -s --sectorsize min block allocation
Btrfs v0.19-16-g075587c-dirty

So does it have any plan to support this feature at btrfs?

Thank you,
Kyungmin Park

Re: Question: Build btrfs filesystem from specific directory.

[Evgeny A. Marchenko]

> 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

Re: Question: Build btrfs filesystem from specific directory.

[Kyungmin Park]

Hi,

On Sat, Jun 12, 2010 at 11:33 AM, Evgeny A. Marchenko <xengine@mail.ru>=
 wrote:
>> 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=3DDIR =A0 =A0 =A0 build file system from directory DI=
R
>> In case of cramfs
>> dirname =A0 =A0root of the filesystem to be compressed
>>
>> But btrfs doesn't support it.
> Maybe because btrfs is not a compressed read-only filesystem

It's just example. it's not matter to support compressed or not.

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

Right, I used it now, but some build machine doesn't have or support
btrfs, it mean can't mount btrfs as loopback.
I just want to create btrfs image from directory without any host
machine dependency such as kernel version and whatever.
To simply, just use the mkfs.btrfs itself.

Thank you,
Kyungmin Park
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