[libvirt] [PATCH] Allow non-file disk backingStores
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:
I think I'm inclined to push the logic for skipping NBD one stage
higher.
I'd rather expect virStorageFileGetMetadata() to return all backing
stores, even if not files. The virDomainDiskDefForeachPath() method
should definitely ignore non-file backing stores though.
So what I'm thinking is to extend the virStorageFileMetadata struct and
just add a 'bool isFile' field to it. Default this field to true, unless
you see the prefix of nbd: in which case set it to false. The
virDomainDiskDefForeachPath() method can then skip over any backing
store with isFile == false
Signed-off-by: Adam Litke <agl(a)us.ibm.com>
Cc: Daniel P. Berrange <berrange(a)redhat.com>
---
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