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block: Introduce BdrvChildRole.update_filename

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There is no good reason for bdrv_drop_intermediate() to know the active
layer above the subchain it is operating on - even more so, because
the assumption that there is a single active layer above it is not
generally true.

In order to prepare removal of the active parameter, use a BdrvChildRole
callback to update the backing file string in the overlay image instead
of directly calling bdrv_change_backing_file().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Kevin Wolf 2017-06-29 19:32:21 +02:00
parent 09d653e617
commit 6858eba09e
2 changed files with 34 additions and 5 deletions
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33
block.c
View File

@ -981,6 +981,21 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options,
*child_flags = flags;
}
static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
const char *filename, Error **errp)
{
BlockDriverState *parent = c->opaque;
int ret;
ret = bdrv_change_backing_file(parent, filename,
base->drv ? base->drv->format_name : "");
if (ret < 0) {
error_setg_errno(errp, ret, "Could not update backing file link");
}
return ret;
}
const BdrvChildRole child_backing = {
.get_parent_desc = bdrv_child_get_parent_desc,
.attach = bdrv_backing_attach,
@ -989,6 +1004,7 @@ const BdrvChildRole child_backing = {
.drained_begin = bdrv_child_cb_drained_begin,
.drained_end = bdrv_child_cb_drained_end,
.inactivate = bdrv_child_cb_inactivate,
.update_filename = bdrv_backing_update_filename,
};
static int bdrv_open_flags(BlockDriverState *bs, int flags)
@ -3470,6 +3486,8 @@ int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
Error *local_err = NULL;
int ret = -EIO;
bdrv_ref(top);
if (!top->drv || !base->drv) {
goto exit;
}
@ -3494,11 +3512,15 @@ int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
}
/* success - we can delete the intermediate states, and link top->base */
backing_file_str = backing_file_str ? backing_file_str : base->filename;
ret = bdrv_change_backing_file(new_top_bs, backing_file_str,
base->drv ? base->drv->format_name : "");
if (ret) {
goto exit;
if (new_top_bs->backing->role->update_filename) {
backing_file_str = backing_file_str ? backing_file_str : base->filename;
ret = new_top_bs->backing->role->update_filename(new_top_bs->backing,
base, backing_file_str,
&local_err);
if (ret < 0) {
bdrv_set_backing_hd(new_top_bs, top, &error_abort);
goto exit;
}
}
bdrv_set_backing_hd(new_top_bs, base, &local_err);
@ -3510,6 +3532,7 @@ int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
ret = 0;
exit:
bdrv_unref(top);
return ret;
}

6
include/block/block_int.h
View File

@ -544,6 +544,12 @@ struct BdrvChildRole {
void (*attach)(BdrvChild *child);
void (*detach)(BdrvChild *child);
/* Notifies the parent that the filename of its child has changed (e.g.
* because the direct child was removed from the backing chain), so that it
* can update its reference. */
int (*update_filename)(BdrvChild *child, BlockDriverState *new_base,
const char *filename, Error **errp);
};
extern const BdrvChildRole child_file;