Bug 189671

Summary:	btrfs send/receive does not retain file attributes
Product:	File System	Reporter:	ataraxia937
Component:	btrfs	Assignee:	Josef Bacik (josef)
Status:	RESOLVED CODE_FIX
Severity:	enhancement	CC:	ataraxia937, dsterba, gotar
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	4.8.10-300.fc25.x86_64	Subsystem:
Regression:	No	Bisected commit-id:

Description ataraxia937 2016-12-04 17:02:50 UTC

When using btrfs send and receive to transfer a subvolume, file attributes (set with chattr) are not copied. I tested this with the 'C' attribute on a directory, which was present in the original subvol, and in the RO snapshot created for use with send, but not in the snapshot created by receive.

Comment 1 David Sterba 2016-12-05 14:49:51 UTC

This is a known problem and will be addressed in v2 of the send/receive protocol update.

https://btrfs.wiki.kernel.org/index.php/Design_notes_on_Send/Receive#Send_stream_v2_draft

Comment 2 David Sterba 2022-10-06 17:38:21 UTC

Partially implemented in send v2.

Comment 3 Tomasz Pala 2022-10-12 10:23:34 UTC

Could you please elaborate the "partially" part a bit? So that we could know what to expect (to be still missing).

Comment 4 David Sterba 2022-10-12 10:58:11 UTC

The protocol v2 now has a command to send the inode attributes/flags (compound name for the chattr/lsattr bits and also for the newish XFLAGS) and the command is also generated when v2 is used.

The receiving side does not apply the flags yet - that's the missing part. In some cases it's not yet possible (lack of interface, like turning on/off the NODATASUM bit), not directly applicable (setting NOCOW on a nonzero file) or tricky (with IMMUTABLE and APPEND bits no changes can be done to the file so they'd have to be unset temporarily).

Now tracked in https://github.com/kdave/btrfs-progs/issues/526.

Comment 5 Tomasz Pala 2022-10-14 15:26:32 UTC

Thank you!