[Libguestfs] Question about "btrfs send/receive" cmd

[Richard W.M. Jones]

On Tue, Jun 23, 2015 at 02:57:30PM +0800, Cao jin wrote:
> Hi,
>     I am considering implement "btrfs send/receive" API in
> libguestfs. But seems its usual condition is incremental backup
> which is pretty complicated (see 5.7.1: http://docs.oracle.com/cd/E37670_01/E37355/html/ol_sendrecv_btrfs.html)
> and not suitable for implementation as I think.
> 
> So I am considering, does it make sense to implement a simplest form:
> 
>     $ btrfs send -f sent_file subvol
>     $ btrfs receive -f sent_file mountpoint
> 
> which just backup a subvolume and restore it.
> 
> Anyone have suggestions?

The natural way would be to map this to FileIn/FileOut so that the
input/output can be streamed to the client.  Compare the tar-in and
tar-out APIs:

https://github.com/libguestfs/libguestfs/blob/master/daemon/tar.c

Rich.

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