Re: [libvirt] [PATCH 4/6] conf: track more fields in backing chain metadata

The current use of virStorageFileMetadata is awkward; to learn some of the information about a child node, you have to read fields in the parent node. This does not lend itself well to modifying backing chains (whether inserting a new node in the chain, or consolidating existing nodes); better would be to learn about a child node directly in that node. This patch sets up some new fields which contain redundant information, although not necessarily in the final desired state for the new fields (see the next patch for actual tests of what is there now). Then later patches will do any refactoring necessary to get the fields to their desired states, and update clients to get the information from the new fields, so we can finally delete the fields that are tracking information about the wrong node. More concretely, compare these three example backing chains: good <- one missing <- two gluster://server/vol/img <- three Pre-patch, querying the chains gives: { .backingStore = "/path/to/good", .backingStoreRaw = "good", .backingStoreIsFile = true, .backingStoreFormat = VIR_STORAGE_FILE_RAW, .backingMeta = { .backingStore = NULL, .backingStoreRaw = NULL, .backingStoreIsFile = false, .backingMeta = NULL, } } { .backingStore = NULL, .backingStoreRaw = "missing", .backingStoreIsFile = false, .backingStoreFormat = VIR_STORAGE_FILE_NONE, .backingMeta = NULL, } { .backingStore = "gluster://server/vol/img", .backingStoreRaw = NULL, .backingStoreIsFile = false, .backingStoreFormat = VIR_STORAGE_FILE_RAW, .backingMeta = NULL, } Deciding whether to ignore a missing backing file (as in virsh vol-dumpxml) or report an error (as in security manager sVirt labeling) requires reading multiple fields. Plus, the format is hard-coded to treat all network protocols as end-of-the-chain, as if they were raw. By the end of this patch series, the goal is to instead represent these three situations as: { .path = "one", .canonPath = "/path/to/one", .type = VIR_STORAGE_TYPE_FILE, .format = VIR_STORAGE_FILE_QCOW2, .backingStoreRaw = "good", .backingMeta = { .path = "good", .canonPath = "/path/to/good", .type = VIR_STORAGE_TYPE_FILE, .format = VIR_STORAGE_FILE_RAW, .backingStoreRaw = NULL, .backingMeta = NULL, } } { .path = "two", .canonPath = "/path/to/two", .type = VIR_STORAGE_TYPE_FILE, .format = VIR_STORAGE_FILE_QCOW2, .backingStoreRaw = "missing", .backingMeta = NULL, } { .path = "three", .canonPath = "/path/to/three", .type = VIR_STORAGE_TYPE_FILE, .format = VIR_STORAGE_FILE_QCOW2, .backingStoreRaw = "gluster://server/vol/img", .backingMeta = { .path = "gluster://server/vol/img", .canonPath = "gluster://server/vol/img", .type = VIR_STORAGE_TYPE_NETWORK, .format = VIR_STORAGE_FILE_RAW, .backingStoreRaw = NULL, .backingMeta = NULL, } } or, for the second file, maybe also allowing: { .path = "two", .canonPath = "/path/to/two", .type = VIR_STORAGE_TYPE_FILE, .format = VIR_STORAGE_FILE_QCOW2, .backingStoreRaw = "missing", .backingMeta = { .path = "missing", .canonPath = NULL, .type = VIR_STORAGE_TYPE_NONE, .format = VIR_STORAGE_FILE_NONE, .backingStoreRaw = NULL, .backingMeta = NULL, } } * src/util/virstoragefile.h (_virStorageFileMetadata): Add path, canonPath, relDir, type, and format fields. Reorder existing fields, and add lots of comments. * src/util/virstoragefile.c (virStorageFileFreeMetadata): Clean new fields. (virStorageFileGetMetadataInternal) (virStorageFileGetMetadataFromFDInternal): Start populating new fields. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- src/util/virstoragefile.c | 26 +++++++++++++++++++++++++- src/util/virstoragefile.h | 36 +++++++++++++++++++++++++++++++----- 2 files changed, 56 insertions(+), 6 deletions(-)