Commit ea80b906 authored by Kevin Wolf's avatar Kevin Wolf Committed by Anthony Liguori
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qcow2: Fix metadata preallocation 



The wrong version of the preallocation patch has been applied, so this is the
remaining diff.

We can't use truncate to grow the image file to the right size because we don't
know if metadata has been written after the last data cluster. In this case
truncate would shrink the file and destroy its metadata. Write a zero sector at
the end of the virtual disk instead to ensure that the file is big enough.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
parent 3aefa744

block/qcow2.c

+3 −1
Original line number Diff line number Diff line
@@ -677,7 +677,9 @@ static int preallocate(BlockDriverState *bs) 
     * EOF). Extend the image to the last allocated sector.

     */

    if (cluster_offset != 0) {

        bdrv_truncate(s->hd, cluster_offset + (num <<  9));

        uint8_t buf[512];

        memset(buf, 0, 512);

        bdrv_write(s->hd, (cluster_offset >> 9) + num - 1, buf, 1);

    }



    return 0;