block: Split BLOCK_OP_TYPE_COMMIT to BLOCK_OP_TYPE_COMMIT_{SOURCE, TARGET}
commitbb00021de0b5908bc2c3ca467ad9a2b0c9c36459
authorFam Zheng <famz@redhat.com>
Thu, 11 Sep 2014 05:14:00 +0000 (11 13:14 +0800)
committerStefan Hajnoczi <stefanha@redhat.com>
Tue, 13 Jan 2015 13:43:29 +0000 (13 13:43 +0000)
tree87cc009a3e868b3bd2dac421dcdfb8bf6043cbda
parent095e4fa4b56cf511cb41005872eeace9a2f24582
block: Split BLOCK_OP_TYPE_COMMIT to BLOCK_OP_TYPE_COMMIT_{SOURCE, TARGET}

Like BLOCK_OP_TYPE_BACKUP_SOURCE and BLOCK_OP_TYPE_BACKUP_TARGET,
block-commit involves two asymmetric devices.

This change is not user-visible (yet), because commit only works with
device names.

But once we enable backing reference in blockdev-add, or specifying
node-name in block-commit command, we don't want the user to start two
commit jobs on the same backing chain, which will corrupt things because
of the final bdrv_swap.

Before we have per category blockers, splitting this type is still
better.

[Resolved virtio-blk dataplane conflict by replacing
BLOCK_OP_TYPE_COMMIT with both BLOCK_OP_TYPE_COMMIT_{SOURCE, TARGET}.
They are safe since the block job runs in the same AioContext as the
dataplane IOThread.
--Stefan]

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
block.c
blockdev.c
hw/block/dataplane/virtio-blk.c
include/block/block.h