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[libvirt] [PATCH v3 02/18] blockjob: shuffle block rebase code



The existing virDomainBlockRebase code rejected the combination of
_RELATIVE and _COPY flags, but only by accident.  It makes sense,
at least for the case of _SHALLOW and not _REUSE_EXT, but to
implement it, libvirt would have to pre-create the file with a
relative backing name.

Meanwhile, the code to forward on to the block copy code is getting
longer, and reorganising the function to have the block pull done
early makes it easier to add even more block copy prep code.

This patch should have no semantic difference other than the quality
of the error message on the unsupported flag combination.

* src/qemu/qemu_driver.c (qemuDomainBlockRebase): Reorder code,
and improve error message of relative copy.

Signed-off-by: Eric Blake <eblake redhat com>
---
 src/qemu/qemu_driver.c | 47 ++++++++++++++++++++++++++++++++---------------
 1 file changed, 32 insertions(+), 15 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 239a300..177d3e4 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -15467,6 +15467,8 @@ qemuDomainBlockRebase(virDomainPtr dom, const char *path, const char *base,
                       unsigned long bandwidth, unsigned int flags)
 {
     virDomainObjPtr vm;
+    const char *format = NULL;
+    int ret = -1;

     virCheckFlags(VIR_DOMAIN_BLOCK_REBASE_SHALLOW |
                   VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT |
@@ -15477,22 +15479,37 @@ qemuDomainBlockRebase(virDomainPtr dom, const char *path, const char *base,
     if (!(vm = qemuDomObjFromDomain(dom)))
         return -1;

-    if (virDomainBlockRebaseEnsureACL(dom->conn, vm->def) < 0) {
+    if (virDomainBlockRebaseEnsureACL(dom->conn, vm->def) < 0)
+        goto cleanup;
+
+    /* For normal rebase (enhanced blockpull), the common code handles
+     * everything, including vm cleanup. */
+    if (!(flags & VIR_DOMAIN_BLOCK_REBASE_COPY))
+        return qemuDomainBlockJobImpl(vm, dom->conn, path, base, bandwidth,
+                                      NULL, BLOCK_JOB_PULL, flags);
+
+    /* If we got here, we are doing a block copy rebase. */
+    if (flags & VIR_DOMAIN_BLOCK_REBASE_COPY_RAW)
+        format = "raw";
+
+    /* XXX: If we are doing a shallow copy but not reusing an external
+     * file, we should attempt to pre-create the destination with a
+     * relative backing chain instead of qemu's default of absolute */
+    if (flags & VIR_DOMAIN_BLOCK_REBASE_RELATIVE) {
+        virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
+                       _("Relative backing during copy not supported yet"));
+        goto cleanup;
+    }
+
+    flags &= (VIR_DOMAIN_BLOCK_REBASE_SHALLOW |
+              VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT);
+    ret = qemuDomainBlockCopy(vm, dom->conn, path, base, format,
+                              bandwidth, flags);
+    vm = NULL;
+ cleanup:
+    if (vm)
         virObjectUnlock(vm);
-        return -1;
-    }
-
-    if (flags & VIR_DOMAIN_BLOCK_REBASE_COPY) {
-        const char *format = NULL;
-        if (flags & VIR_DOMAIN_BLOCK_REBASE_COPY_RAW)
-            format = "raw";
-        flags &= ~(VIR_DOMAIN_BLOCK_REBASE_COPY |
-                   VIR_DOMAIN_BLOCK_REBASE_COPY_RAW);
-        return qemuDomainBlockCopy(vm, dom->conn, path, base, format, bandwidth, flags);
-    }
-
-    return qemuDomainBlockJobImpl(vm, dom->conn, path, base, bandwidth, NULL,
-                                  BLOCK_JOB_PULL, flags);
+    return ret;
 }

 static int
-- 
1.9.3


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