From 61fbb57d74cc44594b5bcb184c350ab18b963291 Mon Sep 17 00:00:00 2001
Message-Id: <61fbb57d74cc44594b5bcb184c350ab18b963291@dist-git>
From: Eric Blake <eblake@redhat.com>
Date: Tue, 24 Feb 2015 11:59:51 +0100
Subject: [PATCH] blockjob: shuffle block rebase code

https://bugzilla.redhat.com/show_bug.cgi?id=1196066

The existing virDomainBlockRebase code rejected the combination of
_RELATIVE and _COPY flags, but only by accident.  It makes sense
to add support for the combination someday, 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, and I'm
not ready to code that in yet.

Meanwhile, the code to forward on to the block copy code is getting
longer, and reorganizing 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.  Pre-patch:

error: unsupported flags (0x10) in function qemuDomainBlockCopy

Post-patch:

error: argument unsupported: Relative backing during copy not supported yet

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

Signed-off-by: Eric Blake <eblake@redhat.com>
(cherry picked from commit 02d2bd7d91c200d1ea1a5b3f78c8b41720cea832)
Signed-off-by: Jiri Denemark <jdenemar@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 f3b909f..162e039 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -15947,6 +15947,8 @@ 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 |
@@ -15957,22 +15959,37 @@ 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
-- 
2.3.0