On 5/5/20 12:38 PM, Alberto Garcia wrote:
Now that the implementation of subclusters is complete we can finally
add the necessary options to create and read images with this feature,
which we call "extended L2 entries".
Signed-off-by: Alberto Garcia <be...@igalia.com>
Reviewed-by: Max Reitz <mre...@redhat.com>
---
What you have looks good, but I didn't notice anything affecting amend.
The simplest option: amend can reject attempts to toggle the extended L2
option (the zstd compression patches take that path). More complicated
is actually supporting it (in either direction, turning it on or off),
which requires rewriting ALL L2 tables in the entry (including any in
internal snapshots), which could be quite time-intensive, and where you
must be careful to stage things so that failures during partial
conversion merely leave leaked clusters rather than a header pointing to
a half-converted state. Either way, one of the iotests should probably
add coverage on what happens when you attempt to amend the bit on or off.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
