diff options
| -rw-r--r-- | qemu-img.c | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/qemu-img.c b/qemu-img.c index 9bd0bb1e47..2d96a491e2 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -3164,7 +3164,7 @@ static int img_rebase(int argc, char **argv) BlockBackend *blk = NULL, *blk_old_backing = NULL, *blk_new_backing = NULL; uint8_t *buf_old = NULL; uint8_t *buf_new = NULL; - BlockDriverState *bs = NULL; + BlockDriverState *bs = NULL, *prefix_chain_bs = NULL; char *filename; const char *fmt, *cache, *src_cache, *out_basefmt, *out_baseimg; int c, flags, src_flags, ret; @@ -3353,6 +3353,12 @@ static int img_rebase(int argc, char **argv) goto out; } + /* + * Find out whether we rebase an image on top of a previous image + * in its chain. + */ + prefix_chain_bs = bdrv_find_backing_image(bs, out_real_path); + blk_new_backing = blk_new_open(out_real_path, NULL, options, src_flags, &local_err); g_free(out_real_path); @@ -3437,6 +3443,23 @@ static int img_rebase(int argc, char **argv) continue; } + if (prefix_chain_bs) { + /* + * If cluster wasn't changed since prefix_chain, we don't need + * to take action + */ + ret = bdrv_is_allocated_above(backing_bs(bs), prefix_chain_bs, + offset, n, &n); + if (ret < 0) { + error_report("error while reading image metadata: %s", + strerror(-ret)); + goto out; + } + if (!ret) { + continue; + } + } + /* * Read old and new backing file and take into consideration that * backing files may be smaller than the COW image. |