Commit e4a86f88 authored Sep 04, 2013 by Paolo Bonzini Committed by Stefan Hajnoczi Sep 06, 2013

qemu-img: always probe the input image for allocated sectors



qemu-img convert can assume "that sectors which are unallocated in the
input image are present in both the output's and input's base images".

However it is only doing this if the output image returns true for
bdrv_has_zero_init().  Testing bdrv_has_zero_init() does not make much
sense if the output image is copy-on-write, because a copy-on-write
image is never initialized to zero (it is initialized to the content
of the backing file).

There is nothing here that makes has_zero_init images special.  The
input and output must be equal for the operation to make sense, and
that's it.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

parent d663640c

qemu-img.c

+19 −21

Original line number	Diff line number	Diff line
		@@ -1502,7 +1502,6 @@ static int img_convert(int argc, char **argv)
		n = bs_offset + bs_sectors - sector_num;
		}

		if (has_zero_init) {
		/* If the output image is being created as a copy on write image,
		assume that sectors which are unallocated in the input image
		are present in both the output's and input's base images (no
		@@ -1523,7 +1522,6 @@ static int img_convert(int argc, char **argv)
		/* The next 'n1' sectors are allocated in the input image. Copy
		only those as they may be followed by unallocated sectors. */
		n = n1;
		}
		} else {
		n1 = n;
		}