I am trying to use a qcow image with libvirt where the backing 'file' is a qemu-nbd server. Unfortunately virDomainDiskDefForeachPath() assumes that backingStore is always a real file so something like 'nbd:0:3333' is rejected because a file with that name cannot be accessed. Note that I am not worried about directly using nbd images. That would require a new disk type with XML markup, etc. I only want it to be permitted as a backingStore The following patch implements danpb's suggestion: Signed-off-by: Adam Litke <agl(a)us.ibm.com&gt; Cc: Daniel P. Berrange <berrange(a)redhat.com&gt; --- src/conf/domain_conf.c | 7 +++++++ src/util/storage_file.c | 16 +++++++++++++++- src/util/storage_file.h | 1 + 3 files changed, 23 insertions(+), 1 deletions(-) diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index fe93711..2d11785 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -7813,6 +7813,13 @@ int virDomainDiskDefForeachPath(virDomainDiskDefPtr disk, depth++; nextpath = meta.backingStore; + /* Stop iterating if we reach a non-file backing store */ + if (nextpath && meta.backingStoreIsFile == false) { + VIR_DEBUG("Stopping iteration on non-file backing store: %s", + nextpath); + break; + } + format = meta.backingStoreFormat; if (format == VIR_STORAGE_FILE_AUTO && diff --git a/src/util/storage_file.c b/src/util/storage_file.c index 6f48b10..6e099ed 100644 --- a/src/util/storage_file.c +++ b/src/util/storage_file.c @@ -509,6 +509,14 @@ virStorageFileMatchesVersion(int format, return true; } +static bool +virBackingStoreIsFile(const char *backing) +{ + /* Backing store is a network block device */ + if (STRPREFIX(backing, "nbd:")) + return false; + return true; +} static int virStorageFileGetMetadataFromBuf(int format, @@ -579,8 +587,14 @@ virStorageFileGetMetadataFromBuf(int format, if (ret == BACKING_STORE_ERROR) return -1; + meta->backingStoreIsFile = false; if (backing != NULL) { - meta->backingStore = absolutePathFromBaseFile(path, backing); + if (virBackingStoreIsFile(backing)) { + meta->backingStoreIsFile = true; + meta->backingStore = absolutePathFromBaseFile(path, backing); + } else { + meta->backingStore = strdup(backing); + } VIR_FREE(backing); if (meta->backingStore == NULL) { virReportOOMError(); diff --git a/src/util/storage_file.h b/src/util/storage_file.h index fb0c005..c4d4650 100644 --- a/src/util/storage_file.h +++ b/src/util/storage_file.h @@ -49,6 +49,7 @@ VIR_ENUM_DECL(virStorageFileFormat); typedef struct _virStorageFileMetadata { char *backingStore; int backingStoreFormat; + bool backingStoreIsFile; unsigned long long capacity; bool encrypted; } virStorageFileMetadata; -- 1.7.1 -- Thanks, Adam