Plans for a library for btrfs?

Plans for a library for btrfs?

[Stef Bon]

Hi,

I'm working on a program (using sqlite, FUSE and btrfs) to provide
backup and version managment
for users. They can enable the backup service for folders they own,
and select files they want to backup using mimetypes.

This program, which I've called fuse-backup, creates backup subvolumes
and snapshots by calling an extrenal script, which does something
like:

btrfs subvolume snapshot -r %PathToBackup%/ %PathToSnapshot%

This works perfect, but are there any plans to do this with a library?

Stef Bon

Re: Plans for a library for btrfs?

[Duncan]

Stef Bon posted on Wed, 27 May 2015 14:31:28 +0200 as excerpted:

> I'm working on a program (using sqlite, FUSE and btrfs) to provide
> backup and version managment for users. They can enable the backup
> service for folders they own, and select files they want to backup using
> mimetypes.
> 
> This program, which I've called fuse-backup, creates backup subvolumes
> and snapshots by calling an extrenal script, which does something like:
> 
> btrfs subvolume snapshot -r %PathToBackup%/ %PathToSnapshot%
> 
> This works perfect, but are there any plans to do this with a library?

A library is covered on the wiki, project ideas page.

https://btrfs.wiki.kernel.org/index.php/Project_ideas#Provide_a_library_covering_.27btrfs.27_functionality

Status: Project not claimed, no patches, but there's a couple possible 
places to start as parts of other projects.  See the link for more.





-- 
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and if you use the program, he is your master."  Richard Stallman

Re: Plans for a library for btrfs?

[David Sterba]

On Wed, May 27, 2015 at 05:39:34PM +0000, Duncan wrote:
> Stef Bon posted on Wed, 27 May 2015 14:31:28 +0200 as excerpted:
> 
> > I'm working on a program (using sqlite, FUSE and btrfs) to provide
> > backup and version managment for users. They can enable the backup
> > service for folders they own, and select files they want to backup using
> > mimetypes.
> > 
> > This program, which I've called fuse-backup, creates backup subvolumes
> > and snapshots by calling an extrenal script, which does something like:
> > 
> > btrfs subvolume snapshot -r %PathToBackup%/ %PathToSnapshot%
> > 
> > This works perfect, but are there any plans to do this with a library?
> 
> A library is covered on the wiki, project ideas page.
> 
> https://btrfs.wiki.kernel.org/index.php/Project_ideas#Provide_a_library_covering_.27btrfs.27_functionality
> 
> Status: Project not claimed, no patches, but there's a couple possible 
> places to start as parts of other projects.  See the link for more.

AFAIK Karel Zak started working on libbtrfs.

https://github.com/karelzak/btrfs-progs/tree/libbtrfs

Re: Plans for a library for btrfs?

[Roman Mamedov]

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On Wed, 27 May 2015 14:31:28 +0200
Stef Bon <stefbon@gmail.com> wrote:

> This program, which I've called fuse-backup, creates backup subvolumes
> and snapshots by calling an extrenal script, which does something
> like:
> 
> btrfs subvolume snapshot -r %PathToBackup%/ %PathToSnapshot%
> 
> This works perfect, but are there any plans to do this with a library?

If this works perfect, then what is the rationale for needing a library?
Do you see a clear reason aside from any vague "it's supposed to be that way".
In the Unix land it is perfectly normal for programs to call other
self-contained programs to do their self-contained jobs:
http://www.catb.org/esr/writings/taoup/html/ch01s06.html#id2877684
Not everything must to be a library linked into your main executable, some
separation and calling external programs to do stuff such as mkfs or snapshot
management seems perfectly fine and even better from the debug-ability
standpoint.

-- 
With respect,
Roman

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Re: Plans for a library for btrfs?

[Goffredo Baroncelli]

On 2015-05-29 16:31, Roman Mamedov wrote:
> On Wed, 27 May 2015 14:31:28 +0200
> Stef Bon <stefbon@gmail.com> wrote:
> 
>> This program, which I've called fuse-backup, creates backup subvolumes
>> and snapshots by calling an extrenal script, which does something
>> like:
>>
>> btrfs subvolume snapshot -r %PathToBackup%/ %PathToSnapshot%
>>
>> This works perfect, but are there any plans to do this with a library?
> 
> If this works perfect, then what is the rationale for needing a library?

The problem in calling another executable, is that is very difficult to parse the program output.
For "btrfs sub snap" it is easy; but what about "btrfs fi df" or "btrfs fi show" ?

> Do you see a clear reason aside from any vague "it's supposed to be that way".
> In the Unix land it is perfectly normal for programs to call other
> self-contained programs to do their self-contained jobs:

Right, but now btrfs is a collection of tools; I don't think that it could e considered a "self-contained programs"... Other programs (eg systemd, udev) rewrite some code in order to avoid to call an external executable. This leads to code duplication with all the associated problems...

> http://www.catb.org/esr/writings/taoup/html/ch01s06.html#id2877684
> Not everything must to be a library linked into your main executable, some
> separation and calling external programs to do stuff such as mkfs or snapshot
> management seems perfectly fine and even better from the debug-ability
> standpoint.





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Re: Plans for a library for btrfs?

[Juan Orti Alcaine]

I'm not a developer, but I read this a days ago. Could it be helpful?

https://blog-vpodzime.rhcloud.com/?p=61
https://github.com/rhinstaller/libblockdev


2015-05-27 14:31 GMT+02:00 Stef Bon <stefbon@gmail.com>:
> Hi,
>
> I'm working on a program (using sqlite, FUSE and btrfs) to provide
> backup and version managment
> for users. They can enable the backup service for folders they own,
> and select files they want to backup using mimetypes.
>
> This program, which I've called fuse-backup, creates backup subvolumes
> and snapshots by calling an extrenal script, which does something
> like:
>
> btrfs subvolume snapshot -r %PathToBackup%/ %PathToSnapshot%
>
> This works perfect, but are there any plans to do this with a library?
>
> Stef Bon
> --
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-- 
Juan Orti
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