[Libguestfs] [PATCH] libvirt: read disk paths from pools (RHBZ#1366049)
Pino Toscano
ptoscano at redhat.com
Tue Sep 20 15:07:23 UTC 2016
A disk of type 'volume' is stored as
<source pool='pool_name' volume='volume_name'/>
and its real location is inside the 'volume_name', as 'pool_name': in
this case, query libvirt for the actual path of the specified volume in
the specified pool.
Adjust the code so that:
- for_each_disk gets the virConnectPtr, needed to do operations with
libvirt
- when extracting the disk filename depending on the type, the code
snippet doing it can directly set 'filename', without setting an XPath
result variable
Only file-based volumes are supported for now; more types can be added
(with proper testing) later on.
---
src/libvirt-domain.c | 131 +++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 117 insertions(+), 14 deletions(-)
diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
index d54814f..50759e3 100644
--- a/src/libvirt-domain.c
+++ b/src/libvirt-domain.c
@@ -40,8 +40,9 @@
#if defined(HAVE_LIBVIRT)
static xmlDocPtr get_domain_xml (guestfs_h *g, virDomainPtr dom);
-static ssize_t for_each_disk (guestfs_h *g, xmlDocPtr doc, int (*f) (guestfs_h *g, const char *filename, const char *format, int readonly, const char *protocol, char *const *server, const char *username, void *data), void *data);
+static ssize_t for_each_disk (guestfs_h *g, virConnectPtr conn, xmlDocPtr doc, int (*f) (guestfs_h *g, const char *filename, const char *format, int readonly, const char *protocol, char *const *server, const char *username, void *data), void *data);
static int libvirt_selinux_label (guestfs_h *g, xmlDocPtr doc, char **label_rtn, char **imagelabel_rtn);
+static char *filename_from_pool (guestfs_h *g, virConnectPtr conn, const char *pool_nane, const char *volume_name);
static void
ignore_errors (void *ignore, virErrorPtr ignore2)
@@ -311,7 +312,7 @@ guestfs_impl_add_libvirt_dom (guestfs_h *g, void *domvp,
* all disks are added or none are added.
*/
ckp = guestfs_int_checkpoint_drives (g);
- r = for_each_disk (g, doc, add_disk, &data);
+ r = for_each_disk (g, virDomainGetConnect (dom), doc, add_disk, &data);
if (r == -1)
guestfs_int_rollback_drives (g, ckp);
@@ -466,6 +467,7 @@ libvirt_selinux_label (guestfs_h *g, xmlDocPtr doc,
*/
static ssize_t
for_each_disk (guestfs_h *g,
+ virConnectPtr conn,
xmlDocPtr doc,
int (*f) (guestfs_h *g,
const char *filename, const char *format,
@@ -509,6 +511,8 @@ for_each_disk (guestfs_h *g,
CLEANUP_XMLXPATHFREEOBJECT xmlXPathObjectPtr xpprotocol = NULL;
CLEANUP_XMLXPATHFREEOBJECT xmlXPathObjectPtr xphost = NULL;
CLEANUP_XMLXPATHFREEOBJECT xmlXPathObjectPtr xpusername = NULL;
+ CLEANUP_XMLXPATHFREEOBJECT xmlXPathObjectPtr xppool = NULL;
+ CLEANUP_XMLXPATHFREEOBJECT xmlXPathObjectPtr xpvolume = NULL;
xmlAttrPtr attr;
int readonly;
int t;
@@ -628,22 +632,65 @@ for_each_disk (guestfs_h *g,
* TODO: secrets: ./auth/secret/@type,
* ./auth/secret/@usage || ./auth/secret/@uuid
*/
+ } else if (STREQ (type, "volume")) { /* type = "volume", use source/@volume */
+ CLEANUP_FREE char *pool = NULL;
+ CLEANUP_FREE char *volume = NULL;
+
+ xpathCtx->node = nodes->nodeTab[i];
+
+ /* Get the source pool. Required. */
+ xppool = xmlXPathEvalExpression (BAD_CAST "./source/@pool",
+ xpathCtx);
+ if (xppool == NULL ||
+ xppool->nodesetval == NULL ||
+ xppool->nodesetval->nodeNr == 0)
+ continue;
+ assert (xppool->nodesetval->nodeTab[0]);
+ assert (xppool->nodesetval->nodeTab[0]->type ==
+ XML_ATTRIBUTE_NODE);
+ attr = (xmlAttrPtr) xppool->nodesetval->nodeTab[0];
+ pool = (char *) xmlNodeListGetString (doc, attr->children, 1);
+
+ /* Get the source volume. Required. */
+ xpvolume = xmlXPathEvalExpression (BAD_CAST "./source/@volume",
+ xpathCtx);
+ if (xpvolume == NULL ||
+ xpvolume->nodesetval == NULL ||
+ xpvolume->nodesetval->nodeNr == 0)
+ continue;
+ assert (xpvolume->nodesetval->nodeTab[0]);
+ assert (xpvolume->nodesetval->nodeTab[0]->type ==
+ XML_ATTRIBUTE_NODE);
+ attr = (xmlAttrPtr) xpvolume->nodesetval->nodeTab[0];
+ volume = (char *) xmlNodeListGetString (doc, attr->children, 1);
+
+ debug (g, "disk[%zu]: pool: %s; volume: %s", i, pool, volume);
+
+ filename = filename_from_pool (g, conn, pool, volume);
+ if (filename == NULL)
+ continue; /* filename_from_pool already called error() */
} else
continue; /* type <> "file", "block", or "network", skip it */
- assert (xpfilename);
- assert (xpfilename->nodesetval);
- if (xpfilename->nodesetval->nodeNr > 0) {
- assert (xpfilename->nodesetval->nodeTab[0]);
- assert (xpfilename->nodesetval->nodeTab[0]->type ==
- XML_ATTRIBUTE_NODE);
- attr = (xmlAttrPtr) xpfilename->nodesetval->nodeTab[0];
- filename = (char *) xmlNodeListGetString (doc, attr->children, 1);
- debug (g, "disk[%zu]: filename: %s", i, filename);
+ /* Allow a disk type to directly get the filename, with no need
+ * for an XPath evaluation.
+ */
+ if (filename == NULL) {
+ assert (xpfilename);
+ assert (xpfilename->nodesetval);
+ if (xpfilename->nodesetval->nodeNr > 0) {
+ assert (xpfilename->nodesetval->nodeTab[0]);
+ assert (xpfilename->nodesetval->nodeTab[0]->type ==
+ XML_ATTRIBUTE_NODE);
+ attr = (xmlAttrPtr) xpfilename->nodesetval->nodeTab[0];
+ filename = (char *) xmlNodeListGetString (doc, attr->children, 1);
+ }
+ else
+ /* For network protocols (eg. nbd), name may be omitted. */
+ filename = safe_strdup (g, "");
}
- else
- /* For network protocols (eg. nbd), name may be omitted. */
- filename = safe_strdup (g, "");
+
+ debug (g, "disk[%zu]: filename: %s", i, filename);
/* Get the disk format (may not be set). */
xpathCtx->node = nodes->nodeTab[i];
@@ -784,6 +831,62 @@ get_domain_xml (guestfs_h *g, virDomainPtr dom)
return doc;
}
+static char *
+filename_from_pool (guestfs_h *g, virConnectPtr conn,
+ const char *pool_name, const char *volume_name)
+{
+ char *filename = NULL;
+ virErrorPtr err;
+ virStoragePoolPtr pool = NULL;
+ virStorageVolPtr vol = NULL;
+ virStorageVolInfo info;
+ int ret;
+
+ pool = virStoragePoolLookupByName (conn, pool_name);
+ if (pool == NULL) {
+ err = virGetLastError ();
+ error (g, _("no libvirt pool called '%s': %s"),
+ pool_name, err->message);
+ goto cleanup;
+ }
+
+ vol = virStorageVolLookupByName (pool, volume_name);
+ if (vol == NULL) {
+ err = virGetLastError ();
+ error (g, _("no volume called '%s' in the libvirt pool '%s': %s"),
+ volume_name, pool_name, err->message);
+ goto cleanup;
+ }
+
+ ret = virStorageVolGetInfo (vol, &info);
+ if (ret < 0) {
+ err = virGetLastError ();
+ error (g, _("cannot get information of the libvirt volume '%s': %s"),
+ volume_name, err->message);
+ goto cleanup;
+ }
+
+ debug (g, "type of libvirt volume %s: %d", volume_name, info.type);
+
+ /* Support only file-based volumes for now. */
+ if (info.type != VIR_STORAGE_VOL_FILE)
+ goto cleanup;
+
+ filename = virStorageVolGetPath (vol);
+ if (filename == NULL) {
+ err = virGetLastError ();
+ error (g, _("cannot get the filename of the libvirt volume '%s': %s"),
+ volume_name, err->message);
+ goto cleanup;
+ }
+
+ cleanup:
+ if (vol) virStorageVolFree (vol);
+ if (pool) virStoragePoolFree (pool);
+
+ return filename;
+}
+
#else /* no libvirt at compile time */
#define NOT_IMPL(r) \
--
2.7.4
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