block: Add support to warn on backing file change without format

For now, this is a mechanical addition; all callers pass false. But
the next patch will use it to improve 'qemu-img rebase -u' when
selecting a backing file with no format.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Message-Id: <20200706203954.341758-10-eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2020-07-06 15:39:53 -05:00 committed by Kevin Wolf
parent b66ff2c298
commit e54ee1b385
6 changed files with 18 additions and 10 deletions

13
block.c
View File

@ -1206,7 +1206,8 @@ static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
}
ret = bdrv_change_backing_file(parent, filename,
base->drv ? base->drv->format_name : "");
base->drv ? base->drv->format_name : "",
false);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not update backing file link");
}
@ -4680,8 +4681,8 @@ int bdrv_check(BlockDriverState *bs,
* image file header
* -ENOTSUP - format driver doesn't support changing the backing file
*/
int bdrv_change_backing_file(BlockDriverState *bs,
const char *backing_file, const char *backing_fmt)
int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file,
const char *backing_fmt, bool warn)
{
BlockDriver *drv = bs->drv;
int ret;
@ -4695,6 +4696,12 @@ int bdrv_change_backing_file(BlockDriverState *bs,
return -EINVAL;
}
if (warn && backing_file && !backing_fmt) {
warn_report("Deprecated use of backing file without explicit "
"backing format, use of this image requires "
"potentially unsafe format probing");
}
if (drv->bdrv_change_backing_file != NULL) {
ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
} else {

View File

@ -3627,7 +3627,7 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
}
ret = bdrv_change_backing_file(blk_bs(blk), qcow2_opts->backing_file,
backing_format);
backing_format, false);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not assign backing file '%s' "
"with format '%s'", qcow2_opts->backing_file,

View File

@ -78,7 +78,7 @@ static int stream_prepare(Job *job)
}
}
bdrv_set_backing_hd(bs, base, &local_err);
ret = bdrv_change_backing_file(bs, base_id, base_fmt);
ret = bdrv_change_backing_file(bs, base_id, base_fmt, false);
if (local_err) {
error_report_err(local_err);
return -EPERM;

View File

@ -3416,7 +3416,8 @@ void qmp_change_backing_file(const char *device,
}
ret = bdrv_change_backing_file(image_bs, backing_file,
image_bs->drv ? image_bs->drv->format_name : "");
image_bs->drv ? image_bs->drv->format_name : "",
false);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not change backing file to '%s'",

View File

@ -405,8 +405,8 @@ void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr);
void bdrv_refresh_limits(BlockDriverState *bs, Error **errp);
int bdrv_commit(BlockDriverState *bs);
int bdrv_make_empty(BdrvChild *c, Error **errp);
int bdrv_change_backing_file(BlockDriverState *bs,
const char *backing_file, const char *backing_fmt);
int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file,
const char *backing_fmt, bool warn);
void bdrv_register(BlockDriver *bdrv);
int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
const char *backing_file_str);

View File

@ -3797,9 +3797,9 @@ static int img_rebase(int argc, char **argv)
* doesn't change when we switch the backing file.
*/
if (out_baseimg && *out_baseimg) {
ret = bdrv_change_backing_file(bs, out_baseimg, out_basefmt);
ret = bdrv_change_backing_file(bs, out_baseimg, out_basefmt, false);
} else {
ret = bdrv_change_backing_file(bs, NULL, NULL);
ret = bdrv_change_backing_file(bs, NULL, NULL, false);
}
if (ret == -ENOSPC) {