Re: [libvirt] [PATCH 4/4] blockcommit: require base below top

The block commit code looks for an explicit base file relative to the discovered top file; so for a chain of: base <- snap1 <- snap2 <- snap3 and a command of: virsh blockcommit $dom vda --base snap2 --top snap1 we got a sane message (here from libvirt 1.0.5): error: invalid argument: could not find base 'snap2' below 'snap1' in chain for 'vda' Meanwhile, recent refactoring has slightly reduced the quality of the libvirt error messages, by losing the phrase 'below xyz': error: invalid argument: could not find image 'snap2' in chain for 'snap3' But we had a one-off, where we were not excluding the top file itself in searching for the base; thankfully qemu still reports the error, but the quality is worse: virsh blockcommit $dom vda --base snap2 --top snap2 error: internal error unable to execute QEMU command 'block-commit': Base '/snap2' not found Fix the one-off in blockcommit by changing the semantics of name lookup - if a starting point is specified, then the result must be below that point, rather than including that point. The only other call to chain lookup was blockpull code, which was already forcing the lookup to omit the active layer and only needs a tweak to use the new semantics. This also fixes the bug exposed in the testsuite, where when doing a lookup pinned to an intermediate point in the chain, we were unable to return the name of the parent also in the chain. * src/util/virstoragefile.c (virStorageFileChainLookup): Change semantics for non-NULL startFrom. * src/qemu/qemu_driver.c (qemuDomainBlockJobImpl): Adjust caller, to keep existing semantics. * tests/virstoragetest.c (mymain): Adjust to expose new semantics. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- src/qemu/qemu_driver.c | 3 +-- src/util/virstoragefile.c | 33 ++++++++++++++++++++------------- tests/virstoragetest.c | 36 +++++++++++++++++------------------- 3 files changed, 38 insertions(+), 34 deletions(-)