diff mbox series

[09/54] block: Open backing image in force share mode for size probe

Message ID 20180206191515.25830-10-mdroth@linux.vnet.ibm.com
State New
Headers show
Series [01/54] target/i386: Fix handling of VEX prefixes | expand

Commit Message

Michael Roth Feb. 6, 2018, 7:14 p.m. UTC 
From: Fam Zheng <famz@redhat.com>

Management tools create overlays of running guests with qemu-img:

  $ qemu-img create -b /image/in/use.qcow2 -f qcow2 /overlay/image.qcow2

but this doesn't work anymore due to image locking:

    qemu-img: /overlay/image.qcow2: Failed to get shared "write" lock
    Is another process using the image?
    Could not open backing image to determine size.
Use the force share option to allow this use case again.

Cc: qemu-stable@nongnu.org
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit cc954f01e3c004aad081aa36736a17e842b80211)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 block.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/block.c b/block.c
index 9a1a0d1e73..f236431da1 100644
--- a/block.c
+++ b/block.c
@@ -4593,10 +4593,11 @@  void bdrv_img_create(const char *filename, const char *fmt,
         back_flags = flags;
         back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
 
+        backing_options = qdict_new();
         if (backing_fmt) {
-            backing_options = qdict_new();
             qdict_put_str(backing_options, "driver", backing_fmt);
         }
+        qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true);
 
         bs = bdrv_open(full_backing, NULL, backing_options, back_flags,
                        &local_err);