[libvirt] [PATCH RFC 01/22] qemu: Make qemuDomainPrepareDiskChainElement aware of remote storage

[Peter Krempa]

Refactor the function to accept a virStorageSourcePtr instead of just
the path, add a check to run it only on local storage and fix callers
(possibly by using a newly introduced wrapper that wraps a path in the
 virStorageSource struct for legacy code)
---
 src/qemu/qemu_driver.c | 77 ++++++++++++++++++++++++++++++++------------------
 1 file changed, 49 insertions(+), 28 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index fca1a91..ac0de1e 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -12013,22 +12013,26 @@ static int
 qemuDomainPrepareDiskChainElement(virQEMUDriverPtr driver,
                                   virDomainObjPtr vm,
                                   virDomainDiskDefPtr disk,
-                                  const char *file,
+                                  virStorageSourcePtr elem,
                                   qemuDomainDiskChainMode mode)
 {
     /* The easiest way to label a single file with the same
      * permissions it would have as if part of the disk chain is to
      * temporarily modify the disk in place.  */
-    char *origsrc = disk->src.path;
-    int origformat = disk->src.format;
-    virStorageSourcePtr origchain = disk->src.backingStore;
+    virStorageSource origdisk;
     bool origreadonly = disk->readonly;
+    virQEMUDriverConfigPtr cfg = NULL;
     int ret = -1;
-    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);

-    disk->src.path = (char *) file; /* casting away const is safe here */
-    disk->src.format = VIR_STORAGE_FILE_RAW;
-    disk->src.backingStore = NULL;
+    /* XXX Labelling of non-local files isn't currently supported */
+    if (virStorageSourceGetActualType(&disk->src) == VIR_STORAGE_TYPE_NETWORK)
+        return 0;
+
+    cfg = virQEMUDriverGetConfig(driver);
+
+    /* XXX This will be easier when disk->src will be a pointer */
+    memcpy(&origdisk, &disk->src, sizeof(origdisk));
+    memcpy(&disk->src, elem, sizeof(*elem));
     disk->readonly = mode == VIR_DISK_CHAIN_READ_ONLY;

     if (mode == VIR_DISK_CHAIN_NO_ACCESS) {
@@ -12051,9 +12055,7 @@ qemuDomainPrepareDiskChainElement(virQEMUDriverPtr driver,
     ret = 0;

  cleanup:
-    disk->src.path = origsrc;
-    disk->src.format = origformat;
-    disk->src.backingStore = origchain;
+    memcpy(&disk->src, &origdisk, sizeof(origdisk));
     disk->readonly = origreadonly;
     virObjectUnref(cfg);
     return ret;
@@ -12061,6 +12063,25 @@ qemuDomainPrepareDiskChainElement(virQEMUDriverPtr driver,


 static int
+qemuDomainPrepareDiskChainElementPath(virQEMUDriverPtr driver,
+                                      virDomainObjPtr vm,
+                                      virDomainDiskDefPtr disk,
+                                      const char *file,
+                                      qemuDomainDiskChainMode mode)
+{
+    virStorageSource src;
+
+    memset(&src, 0, sizeof(src));
+
+    src.type = VIR_STORAGE_TYPE_FILE;
+    src.format = VIR_STORAGE_FILE_RAW;
+    src.path = (char *) file; /* casting away const is safe here */
+
+    return qemuDomainPrepareDiskChainElement(driver, vm, disk, &src, mode);
+}
+
+
+static int
 qemuDomainSnapshotFSFreeze(virDomainObjPtr vm)
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
@@ -12765,9 +12786,9 @@ qemuDomainSnapshotCreateSingleDiskActive(virQEMUDriverPtr driver,
             VIR_FORCE_CLOSE(fd);
         }

-        if (qemuDomainPrepareDiskChainElement(driver, vm, disk, source,
+        if (qemuDomainPrepareDiskChainElement(driver, vm, disk, &snap->src,
                                               VIR_DISK_CHAIN_READ_WRITE) < 0) {
-            qemuDomainPrepareDiskChainElement(driver, vm, disk, source,
+            qemuDomainPrepareDiskChainElement(driver, vm, disk, &snap->src,
                                               VIR_DISK_CHAIN_NO_ACCESS);
             goto cleanup;
         }
@@ -12898,7 +12919,7 @@ qemuDomainSnapshotUndoSingleDiskActive(virQEMUDriverPtr driver,
         (persistDisk && VIR_STRDUP(persistSource, source) < 0))
         goto cleanup;

-    qemuDomainPrepareDiskChainElement(driver, vm, disk, disk->src.path,
+    qemuDomainPrepareDiskChainElement(driver, vm, disk, &disk->src,
                                       VIR_DISK_CHAIN_NO_ACCESS);
     if (need_unlink &&
         virStorageFileStat(&disk->src, &st) == 0 && S_ISREG(st.st_mode) &&
@@ -15208,10 +15229,10 @@ qemuDomainBlockCopy(virDomainObjPtr vm,
     if (VIR_STRDUP(mirror, dest) < 0)
         goto endjob;

-    if (qemuDomainPrepareDiskChainElement(driver, vm, disk, dest,
-                                          VIR_DISK_CHAIN_READ_WRITE) < 0) {
-        qemuDomainPrepareDiskChainElement(driver, vm, disk, dest,
-                                          VIR_DISK_CHAIN_NO_ACCESS);
+    if (qemuDomainPrepareDiskChainElementPath(driver, vm, disk, dest,
+                                              VIR_DISK_CHAIN_READ_WRITE) < 0) {
+        qemuDomainPrepareDiskChainElementPath(driver, vm, disk, dest,
+                                              VIR_DISK_CHAIN_NO_ACCESS);
         goto endjob;
     }

@@ -15222,8 +15243,8 @@ qemuDomainBlockCopy(virDomainObjPtr vm,
     virDomainAuditDisk(vm, NULL, dest, "mirror", ret >= 0);
     qemuDomainObjExitMonitor(driver, vm);
     if (ret < 0) {
-        qemuDomainPrepareDiskChainElement(driver, vm, disk, dest,
-                                          VIR_DISK_CHAIN_NO_ACCESS);
+        qemuDomainPrepareDiskChainElementPath(driver, vm, disk, dest,
+                                              VIR_DISK_CHAIN_NO_ACCESS);
         goto endjob;
     }

@@ -15400,12 +15421,12 @@ qemuDomainBlockCommit(virDomainPtr dom,
      * operation succeeds, but doing that requires tracking the
      * operation in XML across libvirtd restarts.  */
     clean_access = true;
-    if (qemuDomainPrepareDiskChainElement(driver, vm, disk, baseSource->path,
+    if (qemuDomainPrepareDiskChainElement(driver, vm, disk, baseSource,
                                           VIR_DISK_CHAIN_READ_WRITE) < 0 ||
         (top_parent && top_parent != disk->src.path &&
-         qemuDomainPrepareDiskChainElement(driver, vm, disk,
-                                           top_parent,
-                                           VIR_DISK_CHAIN_READ_WRITE) < 0))
+         qemuDomainPrepareDiskChainElementPath(driver, vm, disk,
+                                               top_parent,
+                                               VIR_DISK_CHAIN_READ_WRITE) < 0))
         goto endjob;

     /* Start the commit operation.  Pass the user's original spelling,
@@ -15423,12 +15444,12 @@ qemuDomainBlockCommit(virDomainPtr dom,
  endjob:
     if (ret < 0 && clean_access) {
         /* Revert access to read-only, if possible.  */
-        qemuDomainPrepareDiskChainElement(driver, vm, disk, baseSource->path,
+        qemuDomainPrepareDiskChainElement(driver, vm, disk, baseSource,
                                           VIR_DISK_CHAIN_READ_ONLY);
         if (top_parent && top_parent != disk->src.path)
-            qemuDomainPrepareDiskChainElement(driver, vm, disk,
-                                              top_parent,
-                                              VIR_DISK_CHAIN_READ_ONLY);
+            qemuDomainPrepareDiskChainElementPath(driver, vm, disk,
+                                                  top_parent,
+                                                  VIR_DISK_CHAIN_READ_ONLY);
     }
     if (!qemuDomainObjEndJob(driver, vm))
         vm = NULL;
-- 
1.9.2