| Message ID | 20200429141126.85159-2-mreitz@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: Do not call BlockDriver.bdrv_make_empty() directly | expand |
On 4/29/20 9:11 AM, Max Reitz wrote: > Right now, all users of bdrv_make_empty() call the BlockDriver method > directly. That is not only bad style, it is also wrong, unless the > caller has a BdrvChild with a WRITE or WRITE_UNCHANGED permission. > (WRITE_UNCHANGED suffices, because callers generally use this function > to clear a node with a backing file after a commit operation.) > > Introduce bdrv_make_empty() that verifies that it does. > > Signed-off-by: Max Reitz <mreitz@redhat.com> > --- > include/block/block.h | 1 + > block.c | 23 +++++++++++++++++++++++ > 2 files changed, 24 insertions(+) > Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/include/block/block.h b/include/block/block.h index 8b62429aa4..1dee50419c 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -352,6 +352,7 @@ BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts, 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); void bdrv_register(BlockDriver *bdrv); diff --git a/block.c b/block.c index 03cc5813a2..d6580db0e2 100644 --- a/block.c +++ b/block.c @@ -6792,3 +6792,26 @@ void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp) parent_bs->drv->bdrv_del_child(parent_bs, child, errp); } + +int bdrv_make_empty(BdrvChild *c, Error **errp) +{ + BlockDriver *drv = c->bs->drv; + int ret; + + assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)); + + if (!drv->bdrv_make_empty) { + error_setg(errp, "%s does not support emptying nodes", + drv->format_name); + return -ENOTSUP; + } + + ret = drv->bdrv_make_empty(c->bs); + if (ret < 0) { + error_setg_errno(errp, -ret, "Failed to empty %s", + c->bs->filename); + return ret; + } + + return 0; +}
Right now, all users of bdrv_make_empty() call the BlockDriver method directly. That is not only bad style, it is also wrong, unless the caller has a BdrvChild with a WRITE or WRITE_UNCHANGED permission. (WRITE_UNCHANGED suffices, because callers generally use this function to clear a node with a backing file after a commit operation.) Introduce bdrv_make_empty() that verifies that it does. Signed-off-by: Max Reitz <mreitz@redhat.com> --- include/block/block.h | 1 + block.c | 23 +++++++++++++++++++++++ 2 files changed, 24 insertions(+)