block: check for RESIZE blocker in the QMP command, not bdrv_truncate()

If we check for the RESIZE blocker in bdrv_truncate(), that means a
commit will fail if the overlay layer is larger than the base, due to
the backing blocker.

This is a regression in behavior from 2.0; currently, commit will try to
grow the size of the base image to match the overlay size, if the
overlay size is larger.

By moving this into the QMP command qmp_block_resize(), it allows
usage of bdrv_truncate() within block jobs.

Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

2 files changed, 6 insertions, 3 deletions

diff --git a/block.c b/block.c
index 7d69f312b6..106238d0b7 100644
--- a/block.c
+++ b/block.c
@@ -3483,9 +3483,7 @@ int bdrv_truncate(BlockDriverState *bs, int64_t offset)
         return -ENOTSUP;
     if (bs->read_only)
         return -EACCES;
-    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_RESIZE, NULL)) {
-        return -EBUSY;
-    }
+
     ret = drv->bdrv_truncate(bs, offset);
     if (ret == 0) {
         ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS);
diff --git a/blockdev.c b/blockdev.c
index 03ab153d01..e8bfa3c660 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1819,6 +1819,11 @@ void qmp_block_resize(bool has_device, const char *device,
         return;
     }
 
+    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_RESIZE, NULL)) {
+        error_set(errp, QERR_DEVICE_IN_USE, device);
+        return;
+    }
+
     /* complete all in-flight operations before resizing the device */
     bdrv_drain_all();