path: root/send-stream.h
diff options
authorStefan Behrens <>2013-04-09 19:08:40 +0200
committerDavid Sterba <>2013-04-23 18:56:24 +0200
commit46de1a6ec3dbb0db203baa6c46cb64ba9b000ea2 (patch)
tree72328a9e68fe8367b5833bd8ce94acc9932a6279 /send-stream.h
parent147525f11bc205ee05dc32643567d22fa60465c9 (diff)
Btrfs-progs: btrfs-receive optionally honors the end-cmd
A new option is added to btrfs-receive to change the behavior when an <end cmd> is received in the Btrfs send stream. The traditional behavior (which still is the default) is to continue to read the stream until an EOF condition is encountered. If an <end cmd> is received, afterwards either an EOF or a new <stream header> is expected. The new behavior (if the -e option is set on the command line) is to terminate after an <end cmd> is read without the need for an EOF. This allows the stream (e.g. a single TCP stream) to carry additional data or even multiple Btrfs send streams. Old btrfs-send tools used to encode multiple snapshots like this (with 2 snapshots in this example): <stream header> + <sequence of commands> + <end cmd> + <stream header> + <sequence of commands> + <end cmd> + EOF If the new -e option is set, the expected format is like this: <stream header> + <sequence of commands> + <sequence of commands> + <end cmd> The btrfs-send tool is changed in a seperate commit to always use the new format, i.e. to send an <end cmd> only at the end. Note that the currently existing receivers treat <end cmd> only as an indication that a new <stream header> is following. This means, you can just skip the sequence <end cmd> <stream header> without loosing compatibility. As long as an EOF is following, the currently existing receivers handle the new format (if the two new flags are used) exactly as the old one. The goal of changing the semantic of <end cmd> is to be able to use a single stream (one TCP connection) to multiplex a request/response handshake plus Btrfs send streams, all in the same stream. In this case you cannot evaluate an EOF condition as an end of the Btrfs send stream. You need something else, and the <end cmd> is just perfect for this purpose. Signed-off-by: Stefan Behrens <>
Diffstat (limited to 'send-stream.h')
1 files changed, 2 insertions, 1 deletions
diff --git a/send-stream.h b/send-stream.h
index 92230187..17bc6692 100644
--- a/send-stream.h
+++ b/send-stream.h
@@ -57,7 +57,8 @@ struct btrfs_send_ops {
int btrfs_read_and_process_send_stream(int fd,
- struct btrfs_send_ops *ops, void *user);
+ struct btrfs_send_ops *ops, void *user,
+ int honor_end_cmd);
#ifdef __cplusplus