[Qemu-devel] [PATCH 0/2] block: fix backing file overriding

[Qemu-devel] [PATCH 0/2] block: fix backing file overriding

[Fam Zheng]

The backing.file.filename option is not working as expected: if there's also a
backing file name from the format driver, adding this option fails bdrv_open;
if there's no backing file name info in the image, "info block" doesn't show
the overrided file name.

A test case is updated to catch these issues.

Fam Zheng (2):
  block: fix backing file overriding
  qemu-iotests: add test for backing file overriding

 block.c                    |  7 +++++--
 tests/qemu-iotests/051     | 17 ++++++++++++++++-
 tests/qemu-iotests/051.out | 11 +++++++++++
 3 files changed, 32 insertions(+), 3 deletions(-)

-- 
1.8.3.1

[Qemu-devel] [PATCH 1/2] block: fix backing file overriding

[Fam Zheng]

Providing backing.file.filename doesn't override backing file as expected:

    $ x86_64-softmmu/qemu-system-x86_64 -drive \
        file=/tmp/child.qcow2,backing.file.filename=/tmp/fake.qcow2

    qemu-system-x86_64: -drive \
        file=/tmp/child.qcow2,backing.file.filename=/tmp/fake.qcow2: could not
        open disk image /tmp/child.qcow2: Can't specify 'file' and 'filename'
        options at the same time

With

    $ qemu-img info /tmp/child.qcow2
    image: /tmp/child.qcow2
    file format: qcow2
    virtual size: 1.0G (1073741824 bytes)
    disk size: 196K
    cluster_size: 65536
    backing file: /tmp/fake.qcow2

This fixes it by calling bdrv_get_full_backing_filename only if
backing.file.filename is not provided. Also save the backing file name
to bs->backing_file so the information is correct with HMP "info block".

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/block.c b/block.c
index e176c6f..a2ea39a 100644
--- a/block.c
+++ b/block.c
@@ -978,11 +978,12 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
     } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
         QDECREF(options);
         return 0;
+    } else {
+        bdrv_get_full_backing_filename(bs, backing_filename,
+                                       sizeof(backing_filename));
     }
 
     bs->backing_hd = bdrv_new("");
-    bdrv_get_full_backing_filename(bs, backing_filename,
-                                   sizeof(backing_filename));
 
     if (bs->backing_format[0] != '\0') {
         back_drv = bdrv_find_format(bs->backing_format);
@@ -994,6 +995,8 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
     ret = bdrv_open(bs->backing_hd,
                     *backing_filename ? backing_filename : NULL, options,
                     back_flags, back_drv, &local_err);
+    pstrcpy(bs->backing_file, sizeof(bs->backing_file),
+            bs->backing_hd->file->filename);
     if (ret < 0) {
         bdrv_unref(bs->backing_hd);
         bs->backing_hd = NULL;
-- 
1.8.3.1

[Qemu-devel] [PATCH 2/2] qemu-iotests: add test for backing file overriding

[Fam Zheng]

Test that backing.file.filename option can be parsed and override the
backing file from image (backing file reflected with "info block").

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 tests/qemu-iotests/051     | 17 ++++++++++++++++-
 tests/qemu-iotests/051.out | 11 +++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/tests/qemu-iotests/051 b/tests/qemu-iotests/051
index 1f39c6a..78e1182 100755
--- a/tests/qemu-iotests/051
+++ b/tests/qemu-iotests/051
@@ -45,7 +45,14 @@ _supported_os Linux
 function do_run_qemu()
 {
     echo Testing: "$@"
-    echo quit | $QEMU -nographic -monitor stdio -serial none "$@"
+    (
+        if ! test -t 0; then
+            while read cmd; do
+                echo $cmd
+            done
+        fi
+        echo quit
+    ) | $QEMU -nographic -monitor stdio -serial none "$@"
     echo
 }
 
@@ -57,6 +64,9 @@ function run_qemu()
 size=128M
 
 _make_test_img $size
+cp $TEST_IMG $TEST_IMG.orig
+mv $TEST_IMG $TEST_IMG.base
+_make_test_img -b $TEST_IMG.base $size
 
 echo
 echo === Unknown option ===
@@ -67,6 +77,11 @@ run_qemu -drive file=$TEST_IMG,format=qcow2,unknown_opt=on
 run_qemu -drive file=$TEST_IMG,format=qcow2,unknown_opt=1234
 run_qemu -drive file=$TEST_IMG,format=qcow2,unknown_opt=foo
 
+echo
+echo === Overriding backing file ===
+echo
+
+echo "info block" | run_qemu -drive file=$TEST_IMG,driver=qcow2,backing.file.filename=$TEST_IMG.orig -nodefaults
 
 echo
 echo === Enable and disable lazy refcounting on the command line, plus some invalid values ===
diff --git a/tests/qemu-iotests/051.out b/tests/qemu-iotests/051.out
index 88e8fa7..335fbe3 100644
--- a/tests/qemu-iotests/051.out
+++ b/tests/qemu-iotests/051.out
@@ -1,5 +1,6 @@
 QA output created by 051
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 backing_file='TEST_DIR/t.IMGFMT.base' 
 
 === Unknown option ===
 
@@ -16,6 +17,16 @@ Testing: -drive file=TEST_DIR/t.qcow2,format=qcow2,unknown_opt=foo
 QEMU_PROG: -drive file=TEST_DIR/t.qcow2,format=qcow2,unknown_opt=foo: could not open disk image TEST_DIR/t.qcow2: Block format 'qcow2' used by device 'ide0-hd0' doesn't support the option 'unknown_opt'
 
 
+=== Overriding backing file ===
+
+Testing: -drive file=TEST_DIR/t.qcow2,driver=qcow2,backing.file.filename=TEST_DIR/t.qcow2.orig -nodefaults
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) i^[[K^[[Din^[[K^[[D^[[Dinf^[[K^[[D^[[D^[[Dinfo^[[K^[[D^[[D^[[D^[[Dinfo ^[[K^[[D^[[D^[[D^[[D^[[Dinfo b^[[K^[[D^[[D^[[D^[[D^[[D^[[Dinfo bl^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo blo^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo bloc^[[K^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[D^[[Dinfo block^[[K
+ide0-hd0: TEST_DIR/t.qcow2 (qcow2)
+    Backing file:     TEST_DIR/t.qcow2.orig (chain depth: 1)
+ [not inserted](qemu) q^[[K^[[Dqu^[[K^[[D^[[Dqui^[[K^[[D^[[D^[[Dquit^[[K
+
+
 === Enable and disable lazy refcounting on the command line, plus some invalid values ===
 
 Testing: -drive file=TEST_DIR/t.qcow2,format=qcow2,lazy-refcounts=on
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH 0/2] block: fix backing file overriding

[Kevin Wolf]

Am 22.09.2013 um 14:05 hat Fam Zheng geschrieben:
> The backing.file.filename option is not working as expected: if there's also a
> backing file name from the format driver, adding this option fails bdrv_open;
> if there's no backing file name info in the image, "info block" doesn't show
> the overrided file name.
> 
> A test case is updated to catch these issues.

Thanks, applied to the block branch.

Kevin