First, add a --proto option to allow specifying the desired send
protocol version. It defaults to one, the original version. In a couple
of releases once people are aware that protocol revisions are happening,
we can change it to default to zero, which means the latest version
supported by the kernel. This is based on Dave Sterba's patch.
Also add a --compressed-data flag to instruct the kernel to use
encoded_write commands for compressed extents. This requires an explicit
opt in separate from the protocol version because:
1. The user may not want compression on the receiving side, or may want
a different compression algorithm/level on the receiving side.
2. It has a soft requirement for kernel support on the receiving side
(btrfs-progs can fall back to decompressing and writing if the kernel
doesn't support BTRFS_IOC_ENCODED_WRITE, but the user may not be
prepared to pay that CPU cost). Going forward, since it's easier to
update progs than the kernel, I think we'll want to make new send
features that require kernel support opt-in, whereas anything that
only requires a progs update can happen automatically.
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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