tree e425e2394fa968466ffbe55ca7a2f65b61e053e2
parent 0a156f7c750c4e4e1c5dfb2135debcf399e4e2a7
author Max Reitz <mreitz@redhat.com> 1406062722 +0200
committer Kevin Wolf <kwolf@redhat.com> 1408712084 +0200

qemu-img: Allow source cache mode specification

Many qemu-img subcommands only read the source file(s) once. For these
use cases, a full write-back cache is unnecessary and mainly clutters
host cache memory. Though this is generally no concern as cache memory
is freely available and can be scaled by the host OS, it may become a
concern with thin provisioning.

For these cases, it makes sense to allow users to freely specify the
source cache mode (e.g. use no cache at all).

This commit adds a new switch (-T) for the qemu-img subcommands check,
compare, convert and rebase to specify the cache to be used for source
images (the backing file in case of rebase).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>