On Tue, May 20, 2014 at 02:04:30PM +0800, Fam Zheng wrote:
> This is the common but non-trivial steps to assign or change the
> backing_hd of BDS.
>
> Signed-off-by: Fam Zheng <f...@redhat.com>
> ---
> block.c | 36 +++++++++++++++++++++++-------------
> include/block/block.h | 1 +
> 2 files changed, 24 insertions(+), 13 deletions(-)
>
> diff --git a/block.c b/block.c
> index ef9c1a7..a47118b 100644
> --- a/block.c
> +++ b/block.c
> @@ -1094,6 +1094,21 @@ fail:
> return ret;
> }
>
> +void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
> +{
> +
> + bs->backing_hd = backing_hd;
> + if (!backing_hd) {
> + goto out;
> + }
> + bs->open_flags &= ~BDRV_O_NO_BACKING;
> + pstrcpy(bs->backing_file, sizeof(bs->backing_file),
> backing_hd->filename);
> + pstrcpy(bs->backing_format, sizeof(bs->backing_format),
> + backing_hd->drv ? backing_hd->drv->format_name : "");
> +out:
> + bdrv_refresh_limits(bs);
> +}
> +
> /*
> * Opens the backing file for a BlockDriverState if not yet open
> *
> @@ -1107,6 +1122,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict
> *options, Error **errp)
> char *backing_filename = g_malloc0(PATH_MAX);
> int ret = 0;
> BlockDriver *back_drv = NULL;
> + BlockDriverState *backing_hd;
> Error *local_err = NULL;
>
> if (bs->backing_hd != NULL) {
> @@ -1129,27 +1145,26 @@ int bdrv_open_backing_file(BlockDriverState *bs,
> QDict *options, Error **errp)
> bdrv_get_full_backing_filename(bs, backing_filename, PATH_MAX);
> }
>
> + backing_hd = bdrv_new("", errp);
> +
> if (bs->backing_format[0] != '\0') {
> back_drv = bdrv_find_format(bs->backing_format);
> }
>
> assert(bs->backing_hd == NULL);
> - ret = bdrv_open(&bs->backing_hd,
> + ret = bdrv_open(&backing_hd,
> *backing_filename ? backing_filename : NULL, NULL,
> options,
> bdrv_backing_flags(bs->open_flags), back_drv,
> &local_err);
> if (ret < 0) {
> - bs->backing_hd = NULL;
> + bdrv_unref(backing_hd);
> + backing_hd = NULL;
> bs->open_flags |= BDRV_O_NO_BACKING;
> error_setg(errp, "Could not open backing file: %s",
> error_get_pretty(local_err));
> error_free(local_err);
> goto free_exit;
> }
> -
> - if (bs->backing_hd->file) {
> - pstrcpy(bs->backing_file, sizeof(bs->backing_file),
> - bs->backing_hd->file->filename);
> - }
> + bdrv_set_backing_hd(bs, backing_hd);
>
> /* Recalculate the BlockLimits with the backing file */
> bdrv_refresh_limits(bs);
> @@ -2002,12 +2017,7 @@ void bdrv_append(BlockDriverState *bs_new,
> BlockDriverState *bs_top)
>
> /* The contents of 'tmp' will become bs_top, as we are
> * swapping bs_new and bs_top contents. */
> - bs_top->backing_hd = bs_new;
> - bs_top->open_flags &= ~BDRV_O_NO_BACKING;
> - pstrcpy(bs_top->backing_file, sizeof(bs_top->backing_file),
> - bs_new->filename);
> - pstrcpy(bs_top->backing_format, sizeof(bs_top->backing_format),
> - bs_new->drv ? bs_new->drv->format_name : "");
> + bdrv_set_backing_hd(bs_top, bs_new);
> }
>
> static void bdrv_delete(BlockDriverState *bs)
> diff --git a/include/block/block.h b/include/block/block.h
> index 60e79a8..032828a 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -213,6 +213,7 @@ int bdrv_parse_discard_flags(const char *mode, int
> *flags);
> int bdrv_open_image(BlockDriverState **pbs, const char *filename,
> QDict *options, const char *bdref_key, int flags,
> bool allow_none, Error **errp);
> +void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd);
> int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error
> **errp);
> void bdrv_append_temp_snapshot(BlockDriverState *bs, int flags, Error
> **errp);
> int bdrv_open(BlockDriverState **pbs, const char *filename,
> --
> 1.9.2
>
Reviewed-by: Jeff Cody <jc...@redhat.com>
