diff options
Diffstat (limited to 'block.c')
| -rw-r--r-- | block.c | 27 |
1 files changed, 26 insertions, 1 deletions
@@ -6139,6 +6139,26 @@ void bdrv_img_create(const char *filename, const char *fmt, error_append_hint(&local_err, "Could not open backing image.\n"); goto out; } else { + if (!backing_fmt) { + warn_report("Deprecated use of backing file without explicit " + "backing format (detected format of %s)", + bs->drv->format_name); + if (bs->drv != &bdrv_raw) { + /* + * A probe of raw deserves the most attention: + * leaving the backing format out of the image + * will ensure bs->probed is set (ensuring we + * don't accidentally commit into the backing + * file), and allow more spots to warn the users + * to fix their toolchain when opening this image + * later. For other images, we can safely record + * the format that we probed. + */ + backing_fmt = bs->drv->format_name; + qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, backing_fmt, + NULL); + } + } if (size == -1) { /* Opened BS, have no size */ size = bdrv_getlength(bs); @@ -6152,7 +6172,12 @@ void bdrv_img_create(const char *filename, const char *fmt, } bdrv_unref(bs); } - } /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */ + /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */ + } else if (backing_file && !backing_fmt) { + warn_report("Deprecated use of unopened backing file without " + "explicit backing format, use of this image requires " + "potentially unsafe format probing"); + } if (size == -1) { error_setg(errp, "Image creation needs a size parameter"); |