diff mbox

[v4,09/21] qemu-img: always probe the input image for allocated sectors

Message ID 1377784821-29561-10-git-send-email-pbonzini@redhat.com
State New
Headers show

Commit Message

Paolo Bonzini Aug. 29, 2013, 2 p.m. UTC 
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>
---
 qemu-img.c | 40 +++++++++++++++++++---------------------
 1 file changed, 19 insertions(+), 21 deletions(-)
diff mbox

Patch

diff --git a/qemu-img.c b/qemu-img.c
index b01998b..837f8bc 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1479,28 +1479,26 @@  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
-                   need to copy them). */
-                if (out_baseimg) {
-                    ret = bdrv_is_allocated(bs[bs_i], sector_num - bs_offset,
-                                            n, &n1);
-                    if (ret < 0) {
-                        error_report("error while reading metadata for sector "
-                                     "%" PRId64 ": %s",
-                                     sector_num - bs_offset, strerror(-ret));
-                        goto out;
-                    }
-                    if (!ret) {
-                        sector_num += n1;
-                        continue;
-                    }
-                    /* The next 'n1' sectors are allocated in the input image. Copy
-                       only those as they may be followed by unallocated sectors. */
-                    n = n1;
+            /* 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
+               need to copy them). */
+            if (out_baseimg) {
+                ret = bdrv_is_allocated(bs[bs_i], sector_num - bs_offset,
+                                        n, &n1);
+                if (ret < 0) {
+                    error_report("error while reading metadata for sector "
+                                 "%" PRId64 ": %s",
+                                 sector_num - bs_offset, strerror(-ret));
+                    goto out;
+                }
+                if (!ret) {
+                    sector_num += n1;
+                    continue;
                 }
+                /* 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;
             }